π-Conjugated [2]Catenanes Based on Oligothiophenes and Phenanthrolines: Efficient Synthesis and Electronic Properties.

DOI: 10.1002/chem.201406039

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p-Conjugated [2]Catenanes Based on Oligothiophenes and Phenanthrolines: Efficient Synthesis and Electronic Properties Gnther Gçtz,[a] Xiaozhang Zhu,[a] Amaresh Mishra,[a] Jose-Luis Segura,[b] Elena MenaOsteritz,[a] and Peter Buerle*[a] Dedicated to Prof. Dr. Dr. h.c. Franz Effenberger (University of Stuttgart, Germany) on the occasion of his 85th birthday

Abstract: Novel p-conjugated topologies based on oligothiophenes and phenanthroline have been assembled by combining their outstanding electronic and structural benefits with the specific properties of the topological structure. Macrocycles and catenanes are prepared by using an optimized protocol of transition metal-templated macrocyclization followed by efficient Pd-catalyzed cross-coupling reaction steps. By using this method, [2]catenanes comprising two interlocked p-conjugated macrocycles with different

ring sizes have been synthesized. The structures of the [2]catenanes and corresponding macrocycles are confirmed by detailed 1H NMR spectroscopy and high resolution mass spectrometry. Single crystal X-ray structural analysis of the quaterthiophene–diyne macrocycle affords important insight into the packing features and intermolecular interaction of the new systems. The fully conjugated interlocked [2]catenanes are fully characterized by spectroscopic and electrochemical measurements.

Introduction

tronic devices[8] and as prototypes of molecular machines.[9] To date, most of these interlocked molecular topologies have consisted, at least partially, of flexible and saturated hydrocarbon units, such as oligoethers, aliphatic chains, or the combination of these units with aromatic systems, which are helpful tectons for the required curvatures in the macrocycles. We recently reported the use of metal coordination for the formation of macrocycles within a remarkable [2]catenane[10] that consisted of two interlocked fully p-conjugated phenanthroline-bridged oligothiophene–diyne macrocycles, thus stepping into a new field of conjugated chemical topologies. For the synthesis of this “p-conjugated” [2]catenane, a double templating method was applied. With the aid of CuI, two oligothiophene-substituted and crescent-shaped phenanthrolines (phen) were templated and arranged first to a Sauvage-type [CuI(phen)2] motif. In a second step, the ring closures to the corresponding macrocycles were initiated by complexation of the terminal ethynyl groups, which were attached at each oligothiophene arm, to a PtII center under high-dilution conditions and was accomplished by iodine-mediated reductive elimination of the platinum under CC bond formation. Demetallation by cyanide to remove the CuI template furnished a [2]catenane, in which each macrocycle incorporated extended p-conjugation due to quaterthiophene (4T), phenanthroline (phen), and diacetylene units (Figure 1). The overall yield of the multistep synthesis was very low and included tedious purification processes at each step. Despite the small amount of material we obtained, it was possible to investigate the particular optoelectronic properties of the novel topological structure, revealing that the two interlocked macrocycles influenced each other by through-space donor–acceptor interactions.

The high yield synthesis of catenanes via metal-coordinated intermediates developed by Sauvage et al. more than 30 years ago combined topology with templation and opened the way for the preparation of a variety of complex mechanically linked and interlocked molecular structures.[1] With the unremitting endeavor of chemists, an increasing number of high-order interlocked molecules, such as [n]catenanes,[2] [n]rotaxanes,[3] trefoil knots,[4] Borromean rings,[5] and [n]pseudocatenanes (n 3),[6] have been prepared and realized with various elegant and sophisticated synthetic strategies. In recent years, metal coordination has not only been used to template and pre-organize the building blocks to preform the intertwined structures, but also to catalyze the linking and ring-forming reactions.[7] Besides the synthetic challenges of their aesthetic structures, new emphasis came from potential applications in molecular elec-

[a] Dr. G. Gçtz,+ Dr. X. Zhu,+ ++ Dr. A. Mishra, Dr. E. Mena-Osteritz, Prof. Dr. P. Buerle Institut fr Organische Chemie und Neue Materialien Universitt Ulm, Albert-Einstein-Allee 11, 89081 Ulm (Germany) E-mail: [email protected] [b] Prof. Dr. J.-L. Segura Departamento de Qumica Orgnica, Facultad de Ciencias Qumicas Universidad Complutense de Madrid, 28040, Madrid (Spain) [+] Both authors contributed equally. [++] Current address: Organic Solids Laboratory, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (P. R. China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201406039. Chem. Eur. J. 2015, 21, 1 – 19

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Full Paper 2 A–2 E, which, at a later stage, should induce the desired preformed topology favoring intramolecular cyclization in the crucial catenation step. Various derivatives were used as starting materials for the preparation of [2]catenanes (Scheme 1). These building blocks differ in the length of the (oligo)thiophene unit from a monothiophene (A) to a quinquethiophene (E) and ethyl side chains on every second thiophene unit were used in order to increase solubility (B–E). According to our previously developed protocol, their synthesis was accomplished by a Negishi-type cross-coupling reaction of 2,9-diiodophenanthroline (1) or 2,9-di(5-iodothien-2-yl)phenanthroline (3 A) with the respective lithiated oligothiophenes to furnish 2,9-disubstituted phen units 2 B–2 E with bithienyl (2 B), terthienyl (2 C), quaterthienyl (2 D), and quinquethienyl (2 E) side arms.[11] As the monolithiation yield of oligothiophenes decreased with increasing length of the oligomer, the yields in the subsequent cross-coupling reactions to 2 B–2 E decreased from 56 % to 20 % (Scheme 1).

Figure 1. Example of a [2]catenane based on p-conjugated phenanthrolinebridged quaterthiophene–diyne macrocycles with butyl side chains.[10]

To provide a deeper understanding of the properties of thiophene-based interlocked molecules, we report herein a more effective and convenient synthetic method for the preparation of [2]catenanes including conjugated macrocycles with different ring sizes. The key step was the development of an efficient Pd-catalyzed coupling of the terminal acetylene units at each arm under simultaneous double macrocyclization, which replaced the previously reported two-step Pt-templation/reductive elimination protocol.[10, 11] In comparison to the [2]catenane (including 4T units) and [2]catenate structures (3T or 4T units) described previously, we were able, in addition to obtaining higher yields, to synthesize a novel [2]catenane with enlarged rings (5T units). Furthermore, for the first time, we successfully transformed the diyne units into thiophenes yielding the [2]catenane only consisting of phen and oligothiophene units. To avoid possible steric constraints in the reaction sequences, in the compound series described herein we have employed ethyl groups as the alkyl side chains on the oligothiophene units in place of the previously used butyl.

Results and Discussion Synthesis and characterization of [2]catenanes and related macrocycles The first step was the synthesis of crescent-shaped 2,9-bis(oligothienyl)-substituted phen units &

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Scheme 1. Synthetic steps to starting compounds 2 A–2 E and 3 A. Reagents and conditions: i) N-bromosuccinimide, DMF; ii) Mg, 2,5-dibromothiophene, [Ni(dppp)Cl2], Et2O; iii) 2-pinacolborylthiophene, [Pd2(dba)3], tBu3PH BF4, K3PO4, THF/H2O; iv) [Pd(PPh3)4], THF; v) N-iodosuccinimide, AcOH/DMF/CHCl3 ; dba = dibenzylideneacetone, dppp = 1,3-bis(diphenylphosphino)propane.

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Full Paper Iodination of 2,9-disubstituted phen units 2 A–E with N-iodosuccinimide in a solvent mixture of AcOH/DMF/CHCl3 (2:20:20, v/v) afforded the corresponding diiodo derivatives 3 A–3 E (75– 98 % yield), which were subsequently subjected to a Sonogashira-type cross-coupling reaction with trimethylsilyl (TMS) acetylene to afford the TMS-protected series 4 B–4 E in 46– 97 % yields (Scheme 2). Deprotection of 4 C–4 E with CsF furnished acetylene-terminated derivatives 5 C–5 E in nearly quantitative yields. Compounds 5 C–5 E were complexed with CuI tetrafluoroborate to afford the corresponding homoleptic com-

plexes [Cu(5 C)2]BF4, [Cu(5 D)2]BF4, and [Cu(5 E)2]BF4 with pseudotetrahedral preorganization of the phen units around the CuI center, which should favor intramolecular ring closure to the corresponding catenates, even under rather concentrated conditions. The intramolecular oxidative coupling of the acetylene arms in these complexes was initially explored with the Cu complex [Cu(5 D)2]BF4 by applying a Glaser–Eglinton dimerization under dilution conditions (Scheme 3).[12] Much to our surprise, the reaction did not result in the formation of the expected catenate [Cu(6 D)2]BF4, but exclusively furnished macrocycle 6 D in 78 % yield. We attributed this reaction behavior to the strong coordinating power of pyridine, which was used as solvent and may coordinate to the CuI template by disintegrating the ligand assembly. Under the same reaction conditions, macrocycle 6 D was directly obtained from the acetylene intermediate 5 D in 83 % yield (Scheme 3). These observations led us to exclude coordinating solvents from the following reactions for the synthesis of [2]catenate [Cu(6 D)2]BF4 with the present template method. However, a variety of coupling reactions were Scheme 2. Synthetic route to phen–oligothiophene [2]catenates and [2]catenanes. Reagents and conditions: v) Nperformed under modified Egliniodosuccinimide, AcOH/DMF/CHCl3 ; vi) HC CTMS, [Pd(PPh3)2Cl2], CuI, PPh3, Et3N, pyridine; vii) CsF, THF/MeOH; ton or Hay conditions in weakly viii) [Cu(CH3CN)4]BF4, CH2Cl2 ; ix) [Pd(dppp)Cl2], CuI, TMEDA, BrCH2COOCH3, DCM; x) KCN, CH2Cl2/H2O; xi) CuCl, or non-coordinating solvents Cu(OAc)2·H2O, pyridine.

Scheme 3. Macrocyclization of [Cu(5 D)2]BF4 and 5 D by applying Glaser–Eglinton conditions, yielding macrocycle 6 D in both cases. Reagents and conditions: xi) CuCl, Cu(OAc)2·H2O, pyridine. Chem. Eur. J. 2015, 21, 1 – 19

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Full Paper such as dichloromethane (DCM), DMF, or acetonitrile, but they all failed.[13, 14] Considering these results, we then used Pd-catalyzed acetylene–acetylene coupling[15] in DCM as solvent, which seems to be a suitable alternative for the synthesis of this type of p-conjugated catenanes. Thus, by employing 10 mol % [Pd(dppp)Cl2], CuI, BrCH2COOCH3, and tetramethylethylenediamine (TMEDA) in DCM as non-coordinating solvent, the intramolecular acetylene-acetylene coupling of copper template [Cu(5 D)2]BF4 proceeded efficiently to result in [2]catenate [Cu(6 D)2]BF4. The use of THF as solvent or Et3N as a different base, however, did not lead to product formation. After removal of inorganic salts by passing the crude reaction mixture through a silica column, [2]catenate [Cu(6 D)2]BF4 was obtained together with a mixture of byproducts with similar chromatographic retention times (Scheme 2). Due to the difficulty in separating [2]catenate [Cu(6 D)2]BF4 from the uncyclized precursor and byproducts, we directly subjected the crude product to a decomplexation reaction with potassium cyanide (KCN) in a water–DCM mixture. After purification of the product by size exclusion chromatography (SEC), [2]catenane (6 D)2 was successfully isolated in an appreciable overall yield of 47 % in four steps (calculated from 4 D as starting material). As complexation and decomplexation are reversible processes, [2]catenate [Cu(6 D)2]BF4 was independently prepared in quantitative yield and high purity by reaction of [2]catenane (6 D)2 with [Cu(CH3CN)4]·BF4. Characterization of [2]catenane (6 D)2 was performed by high-resolution mass spectrometry (HR-MS) and 1H NMR spectroscopy. HR-MS of [2]catenane (6 D)2 generated ions corresponding to [(6 D)2 + H] + at the expected m/z value of 2213.4 Da with correct isotopic distribution. 1H NMR spectra of [2]catenane (6 D)2 and macrocycle 6 D at 360 K showed well-resolved resonances in the aromatic region (Figure 2, bottom part). The absence of any signal for an acetylenic proton in the aliphatic region supports the formation of cyclic structures bridged by diacetylenes. The corresponding aromatic signals detected for [2]catenane (6 D)2 are shifted upfield from those of macrocycle 6 D due to the topological influence of localized ring currents, which result in a shielding effect. Temperaturedependent NMR measurements ranging from room temperature to 100 8C revealed no fundamental changes in the spectra.

Therefore, we conclude that dynamic rotation of the two interlocked macrocyclic rings in [2]catenane (6 D)2 is hindered, in a similar manner to our previously reported butyl-substituted [2]catenane.[10] Finally, we tested the general applicability of our newly developed method for the preparation of other thiophene-based catenanes comprising either smaller or larger conjugated macrocycles. Starting from TMS-protected phenanthroline–oligothiophene 4 C, the small [2]catenate [Cu(6 C)2]BF4 was successfully obtained in a 20 % overall yield after treatment with an excess of aqueous KBF4 solution to remove unwanted counter ions. The relatively low yield of the target compound is ascribed to steric congestion of the smaller interlocked macrocyclic rings (terthiophene (3T) units) in comparison to the abovedescribed larger [2]catenate analogue [Cu(6 D)2]BF4, incorporating quaterthiophene (4T) units. As was the case for the previously described analogous butyl-substituted [2]catenate,[10, 11a] the corresponding [2]catenane (6 C)2 could not be isolated by decomplexation with cyanide. Starting from ligand 4 E, complex [Cu(5 E)2]BF4 was obtained and then successfully cyclized under Pd catalysis to afford Cu [2]catenate [Cu(6 E)2]BF4. After usual decomplexation with cyanide the largest “conjugated” [2]catenane to date, (6 E)2 containing quinquethiophene (5T) units, was isolated in an overall yield of 30 % (Scheme 2). The developed template strategy was also successful in the synthesis of parent macrocycle 6 E, starting from the same precursor 4 E. In this case, to avoid the formation of [2]catenate [Cu(6 E)2]BF4 via homoleptic complexation, we used 2,9-dimesitylphenanthroline (DMesPhe)[16] as a “dummy” ligand, which is known to quantitatively form heteroleptic complexes.[17] Thus, complex [Cu(5 E·DMesPhe)]·BF4 was readily obtained after deprotection of 4 E with CsF and was subjected to the Pd-catalyzed acetylene-coupling reaction under optimized conditions. Subsequent decomplexation of the intermediate product with KCN furnished macrocycle 6 E, which was purified by SEC on polystyrene beads with THF as eluent and isolated in 48 % overall yield over four reaction steps (Scheme 4). The formation of macrocycle 6 E and [2]catenane (6 E)2 was confirmed by HR-MS and 1H NMR spectroscopy. The changes in 1 H NMR resonances with assignment of the respective protons for macrocycle 6 E and [2]catenane (6 E)2 are depicted in Figure 2 c and d. The same trends were observed as for the smaller pair, [2]catenane (6 D)2 and macrocycle 6 D, that is, most aromatic signals of [2]catenane (6 D)2 were shifted upfield and shielded due to the mutual interaction of the interlocked macrocycles. Exceptions are protons B’’, C’’, and C’’’’, located on thiophenes 3 and 5 in (6 E)2, respectively, which are shifted downfield. Conversion of the diyne units into thiophenes yielding oligothiophene–phenanthroline macrocycles A direct pathway to a [2]catenane consisting of only thiophene and phen units requires the conversion of the diyne bridges into thiophene units, which is typically done by reaction with sulfide or hydrogen sulfide (Scheme 5).[18] The treatment of

Figure 2. 1H NMR (C2D2Cl4, 360 K, 500 MHz) spectra of the aromatic region of a) 4T macrocycle 6 D; b) 4T [2]catenane (6 D)2 ; c) 5T macrocycle 6 E; d) 5T [2]catenane (6 E)2. Numbers and characters refer to protons of the phenanthroline and oligothiophene unit, respectively, depicted in Schemes 3 and 4.

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Scheme 4. Synthesis of macrocycle 6 E via heteroleptic copper(I) complex [Cu(5 E·DMesPhe)]BF4 (DmesPhe = 2,9-dimesityl-1,10-phenanthroline). Reagents and conditions refer to Scheme 2.

Scheme 5. Conversion of diacetylene-bridged macrocycle 6 D and [2]catenane (6 D)2 to the corresponding derivatives 7 and (7)2. Conditions and reagents: xii) Na2S, 2-MeOCH2CH2OH/DMF, 120 8C, 2 h, and 140 8C, 60 h for 6 D and (6 D)2, respectively.

the diyne precursors, providing beneficial conditions for further investigation of their optoelectronic properties. The structure of both conjugated macrocycle 7 and [2]catenane (7)2 have been confirmed by HR-MS and NMR spectroscopy. The 1H NMR spectra of precursor macrocycle 6 D and target macrocycle 7 measured in [D2]tetrachloroethane at 360 K are

diyne macrocycle 6 D or catenane (6 D)2 with sodium sulfide in a 2-methoxyethanol/DMF solvent mixture furnished macrocycle phen–C9T 7 and corresponding [2]catenane (7)2 in 38 % and 10 % yields, respectively, after chromatographic purification on silica gel. The solubilities of the novel compounds in halogenated solvents are remarkably increased compared to Chem. Eur. J. 2015, 21, 1 – 19

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Full Paper shown in Figure 3. Compared to diyne-bridged macrocycle 6 D, the thiophene protons B and C in 7 underwent upfield shifts of 0.17 and 0.03 ppm, respectively. The relatively large shift observed for thiophene proton B is likely due to a conformational change of the phen ring in 7 leading to a more pronounced

namic rotation of the two interlocked macrocycles in [2]catenane (7)2 is still hindered. From these observations and the fact that remetallation of the [2]catenane with Cu + to the corresponding [2]catenate proceeds very smoothly and quantitatively (see above), we conclude that, in the most probable conformation, the two macrocycles are arranged in a way that the phen units are situated at the center of the catenane. This rotamer structure is very likely, because stabilization due to intramolecular p–p and donor–acceptor interactions[10] is apparent (Scheme 5) and will be used as the starting point in the discussion of the electrochemical results (see below).

Figure 3. The aromatic region of the 1H NMR (C2D2Cl4, 360 K, 500 MHz) spectra of the macrocycles 6 D (a) and 7 (b).

X-ray single-crystal structure analysis of macrocycle 6D The geometrical structure of macrocycle 6 D and packing in the solid state was confirmed by X-ray single crystal analysis. Single crystals suitable for X-ray diffraction were grown from a THF/dioxane mixture at room temperature. The crystals belong to the triclinic space group P1¯ with two molecules of 6 D and six disordered solvent molecules in the unit cell.[19] Isotropic refinement led to a satisfactory R-factor of 5.96 %. The top view of an individual molecule of 6 D resembles an almost flat ellipse with the alkyl chains pointing out of the molecular plane (Figure 5). The diyne bridge is bent and deviates from ideal linearity by about 368 (Figure 5 a and Table S1 in the Supporting Information), similar to what is observed in cyclodimeric terthiophene–diyne, the precursor of cyclo[8]thiophene.[19] Due to a limited aperture angle of about 558 associated with substitution at the 2- and 9-positions of phen, the two adjacent “a-thiophenes” show an anti conformation relative to the thiophenic backbone, which releases additional ring strain and disclose near coplanarity with the phen unit with torsion angles of only 1.5(4)8 and 8.1(4)8 (see the Supporting Information, Table S2). Further thiophene units in the macrocycle are oriented in a syn conformation, contributing to the circular shape of the molecule. The phen unit is slightly twisted, creating a torsion angle of about 4.268 and the plane of the phen acceptor unit is additionally tilted by around 78 with respect to the thiophene backbone (Figure 5 b and Table S2). Aromatic delocalization throughout the macrocycle is confirmed by expected alternations of bond length along the conjugated pathway and those in the thiophene units lie in the similar range as for linear oligothiophenes (see the Supporting Information, Table S3). The distances between sulfur atoms arranged in a syn conformation (d = 3.084–3.139 ) in the macrocycle were found to be far below the sum of the van der Waals radii (3.6 ), therefore contributing to the ring strain. The unit cell of the macrocycle 6 D contains two molecules packed in an antiparallel fashion with phen moieties on top of the respective adjacent thiophenes, revealing donor–acceptortype p–p interactions with a close interplanar distance of 3.338 (Figure 5 c and Table S4 in the Supporting Information). Figure 6 a shows the molecular packing of the macrocycles in the (1 1 4) plane. In this plane the macrocycles are packed in opposing orientation with the point dipole directed towards the phen moiety. Additionally, they are stabilized by partly dis-

ring strain. This hypothesis is corroborated by simultaneous downfield shifts by 0.04 and 0.01 ppm of the phen protons 3 and 4, which are adjacent to this thiophene unit. In contrast, no major shift was observed for phen proton 5 and thiophene protons B’’ and C’’. The different displacements in the chemical shift values for the two types of thiophene units in macrocycles 6 D and 7 can be rationalized in terms of a more pronounced conformational change of the thiophenes next to phen compared to the more remote ones. Figure 4 shows the aromatic region of the 1H NMR spectrum of 7 in comparison to [2]catenane (7)2. The proton signals were clearly assigned due to the remarkable differences be-

Figure 4. The aromatic region of the 1H NMR (CD2Cl2, 300 K, 500 MHz) spectra of macrocycle 7 (a) and [2]catenane (7)2 (b). Numbers and characters refer to protons of the phenanthroline and oligothiophene unit, respectively, depicted in Scheme 5.

tween the coupling constants of the phen protons (3J(3,4) = 8 Hz) and the thiophene b-protons (3J(3,4) = 4 Hz). Characteristically, all resonances of the catenane were shifted upfield. This effect was particularly significant for thiophene protons at position C. Because of the vicinity and interaction of the interlocked macrocycles, those signals corresponding to protons B’’ and C’’ of the thiophene are further split in the spectrum of the [2]catenane. Additionally, the resonances of the phen protons at the 3-, 4-, and 5-positions and the thiophene protons B and C are broadened at room temperature. Taking into account the behavior of the precursor [2]catenane (6 D)2, free rotation of both entangled macrocycles in [2]catenane (7)2 is less probable because of the limited size of the macrocyclic subunit 7. The relative signal broadening also suggests that the dy&

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Figure 5. Molecular structure of macrocycle 6 D front (a) and side (b) view in the crystal lattice (C: dark gray; H: white; N: blue; S: yellow; solvent molecules are omitted for clarity); c) molecular packing view of macrocycle 6 D in the unit cell.

ordered solvent molecules in the cavities and voids (not shown). Due to a displacement of successive layers deviating from the dipole direction, different types of intermolecular interactions between the macrocycles can be observed (Figure 6 b and Table S4). The macromolecules are organized in such a way that each molecule of 6 D interacts via p–p interactions with six neighbouring molecules. In the opposite direction to the described donor–acceptor-type p–p interactions between the phen units and the a-thiophenes, the phen unit, together with one athiophene ring, approach the g- and d-thiophene units of the adjacent macrocycle with a shortest C···C distance of 3.347 (see the Supporting Information, Table S4). An additional intermolecular p–p interaction was also observed between the band g-thiophene units arranged parallel to each other with shortest interlayer C···C and C···S distances of 3.69 and 3.64 , respectively (see the Supporting Information, Table S4). In conclusion, the molecular packing of the macrocycles is mainly governed by dipole and p–p interactions of the thiophene and phen units, which are not much perturbed by the alkyl side chains. The latter are mainly arranged to fill the voids rather than to support self-organization via van der Waals interactions. In comparison to this crystal structure, cyclo[10]thioChem. Eur. J. 2015, 21, 1 – 19

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Figure 6. a) Molecular packing view of macrocycle 6 D in the single crystal perpendicular to the (1 1 4) plane. The red arrow indicates the point dipole in the donor–acceptor macrocycle; b) packing view showing the interactions of two layers of macrocycles along (1 1 4) plane (the macrocycle in the top layer is colored red for clarity).

phene, which is a similar macrocyclic oligothiophene, also arranges in molecular layers but, due to the longer butyl side chains, the distances between the macrocycles become larger concomitantly with a decrease in p–p interactions.[20] Detailed data on bond lengths, angles, and torsion angles are collected in the Supporting Information. Steady-state optical spectroscopy The photophysical properties of the novel catenanes and macrocycles were investigated in order to identify structure–property relationships. In this series, the conjugated macrocycles and catenanes consist of an oligothiophene donor and a phen acceptor unit in combination with an additional diyne bridge, as in 6 D, 6 E, (6 D)2, and (6 E)2, or without one, as in 7 and (7)2. 7


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Full Paper Representative absorption and fluorescence spectra of macrocycles 6 D and 6 E in DCM are given in Figure 7 and the spectroscopic data are summarized in Table 1. All mixed macrocycles revealed an optical absorption behavior similar to those of

Figure 8. Normalized absorption and emission spectra of macrocycle 7 and catenane (7)2 in dichloromethane.

Although the optical properties of conjugated macrocycles can be influenced by a series of parameters, as described above, it is remarkable to observe that the shape and position of the absorption bands only slightly changes in the case of a catenane topology. The comparison between a macrocycle and the corresponding [2]catenane is representatively depicted in Figure 8 for the pair 7 and (7)2 in agreement with previous measurements.[10] Although the lmax values for the S0 !S2 transition are clearly detectable in the spectra and differ by only 5 nm (Table 1), a direct determination of the corresponding maxima for the S0 !S1 transition is more complicated, as this band is not well resolved. Therefore, we applied Gauss deconvolution on the spectra of 7 and (7)2, resulting in satisfactory figures of merit in curve fitting of R2 = 0.99997 and 0.99996, respectively, and in lmax values of 467.4 0.4 nm and 473.8 0.6 nm for the S0 !S1 transition of macrocycle 7 and catenane (7)2, respectively. In contrast to this bathochromic shift of 7 nm, a hypsochromic displacement of 5 nm was observed for the S0 !S2 transition of the intertwined structure, which is likely attributable to the small size of the macrocycle. We conclude from these results that both macrocycles in catenane (7)2 electronically behave nearly independent of each other, which is also expressed by the finding that the molar absorption coefficient of the catenane (7)2 is nearly doubled that of the parent macrocycle 7, thus indicating an additive contribution of both rings in the interlocked system. This is also true for the other systems 6 D/(6 D)2 and 6 E/(6 E)2 (Table 1). Compared to the corresponding absorption bands, the emission bands of macrocycles 6 D, 6 E, and 7 are structured due to vibronic coupling, indicating stiffer and more planar excitedstate structures. A similar feature was earlier observed in a series of macrocyclic oligothiophenes.[23] A first maximum, often only represented as a shoulder, is observed between 555 and 569 nm, followed by peak emissions at around 600 nm. In comparison to the corresponding macrocycles, the emission bands for [2]catenanes (6 D)2, (7)2, and (6 E)2 are bathochromically shifted and somewhat reduced in intensity. This behavior can be assigned to a quenching process arising from an “intracatenane” charge-transfer interaction between the oligothiophene donor of one macrocycle and the phen acceptor of the other.[10]

Figure 7. Normalized absorption and emission spectra of macrocycles 6 D and 6 E in dichloromethane.

Table 1. Photophysical properties of macrocycles 6 D, 6 E, 7, and [2]catenanes (6 D)2, (6 E)2, and (7)2.

6D (6 D)2 6E (6 E)2 7 (7)2

labs [nm]

e [105 L mol1 cm1]

lem [nm]

416 419 422 421 407,480(sh) 402,480(sh)

1.26 2.15 0.99 2.21 0.69 1.16

555, 564, 569, 584, 568, 574,

599 608 596 606 602 606

all-thiophene systems such as cyclo[10]- or cyclo[15]thiophene.[21] The long-wavelength absorption of the fully conjugated macrocycles mainly comprises two transitions, a strong S0 !S2 transition observed at higher energies and a shoulder at lower energy, assigned to the S0 !S1 transition. The weaker intensity of the latter is in agreement with a forbidden transition, in particular for smaller ring sizes,[22] which was confirmed by theoretical calculations.[23] For diyne macrocycle 6 D an absorption band with a maximum at 416 nm and a tail at lower energies were detected, whereas larger macrocycle 6 E revealed a slight bathochromic shift of the band to lmax = 422 nm, as expected for a system with increased conjugated chain length. S0 !S2 and S0 !S1 transitions merge with increasing ring size, as indicated in 6 E, due to reduced ring strain. In comparison to our previously reported butyl-substituted diyne macrocycle,[10] a 4 nm bathochromic shift was observed for the ethyl-substituted derivative 6 D. Conversion of the diyne bridge in 6 D into a thiophene unit in macrocycle 7 resulted in a hypsochromic shift of 9 nm to lmax = 407 nm and a decrease in the extinction coefficient as a result of the expected ring contraction, which indicates both an electronic and a conformational change in the macrocyclic system. The resolution of the two absorption transitions, S0 !S1 and S0 !S2, is more pronounced in the case of phen–oligothiophene macrocycle 7 compared to the diyne-bridged derivative 6 D, indicative of a higher ring strain and deviation of the units from planarity (Figures 7 and 8). &

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Full Paper Electrochemical characterization After the determination of the optical properties, the redox properties of the donor–acceptor macrocycles 6 D, 6 E, 7 and the corresponding [2]catenanes (6 D)2, (6 E)2, (7)2 are of high interest in order to evaluate the (shared) influence of the various moieties in the macrocycles and catenanes on the electrochemical behavior and the stabilization of charged species. The ring systems were investigated in great detail, analysed, and compared to each other with respect to a systematic variation of ring size, linkage (diyne vs. thiophene), and topology (macrocycle vs. catenane). Dichloromethane and tetrabutylammonium hexafluorophosphate (TBAPF6 ; 0.1 m) were used as electrolyte and potentials were referenced to the ferrocene/ferricenium (Fc/Fc + ) redox couple. The data are summarized in Table 2 and Table 3 and partly shown in Figures 9 and 10. Firstly, we will describe the cyclic voltammetry (CV) studies and complex redox properties of diyne macrocycles 6 D and 6 E, which contain quaterthiophene (4T) and quinquethiophene (5T) moieties as relevant electrophores. Thus, the influence of the ring size on the redox properties can be evaluated. Secondly, we will analyze and compare the electrochemistry of phen–9T macrocycle 7, comprising a nonithiophene moiety as extended electrophore, which allows the comparison of the bridging unit diyne vs. thiophene. Thirdly, the corresponding interlocked [2]catenane (7)2 will be analyzed and compared to the underlying macrocycle 7. Thus, the influence of interactions of the various electrophores can be evaluated in dependence of the topology. In general, the cyclic voltammograms, as well as the deduced time semi-derivative convoluted CVs,[24] showed very complex redox behavior due to aggregation/dimerization phenomena of the oxidized species, which was already determined from investigations on cyclo[n]thiophenes.[21] We additionally determined the number of transferred electrons per redox wave of each macrocycle and [2]catenane by a rotating disc electrode, in comparison to the one-electron transfer redox couple Fc/Fc + .[25] Nevertheless, the unambiguous assignment and the interpretation of the individual redox waves turned out to be a difficult task. The reduction of the phen unit in the macrocycles and catenanes is irreversible at quite negative potentials (Ered 2.1 V) and barely influenced by structural changes in the macrocyclic system[10] and will therefore not be discussed further.

Figure 9. Time semi-derivative convoluted cyclic voltammograms of diyne macrocycles 6 D and 6 E (left), and of phen–9T macrocycle 7 (right). Dotted vertical lines define regions with integer number of transferred electrons.

Table 2. Oxidation potentials of macrocycles 6 D, 6 E, 7 in comparison to open derivative phen-4T 2 D.[10]

2D 6D 6E 7

The time semi-derivative convoluted CVs of macrocycles 6 D and 6 E are shown in Figure 9 (left). Their shapes are quite similar and display two prominent redox waves, the first (E1) covering a potential regime at 0.2–0.5 V and the second (E2) at 0.7– 1 V for 6 D and 0.6–0.9 V for 6 E. Each of the redox waves comprised only partially resolved shoulders (E1’, E2’), which are smaller in intensity. The determined redox potentials of macrocycle 6 D (E1 = 0.34 V; E1’ = 0.44 V; E2’ = 0.81 V; E2 = 0.92 V) are fully comparable to the previously reported corresponding www.chemeurj.org


E1’ [V]

E2’ [V]

E2 [V]

E3 [V]

0.38 0.34 0.31 0.18

0.46 0.44 0.41 0.34

0.73 0.81 0.67 0.63

– 0.92 0.78 0.72

– – – 0.88

butyl derivative.[10] Compared to the smaller 6 D, the redox potentials of enlarged macrocycle 6 E (E1 = 0.31 V; E1’ = 0.41 V; E2’ = 0.67 V; E2 = 0.78 V) were without exception shifted negatively, correlating well with an extended conjugated system of the electrophores (Table 2). Determination of the transferred electrons by comparison of the integrated waves with that of ferrocene in equimolar concentration revealed a first one-electron transfer at lower (E1/E1’) and a second at higher potentials (E2’/E2). Therefore and as an important feature, the diyne macrocycles 6 D and 6 E were oxidized by transfer of two electrons and form stable radical cations and dications. The detailed assignment of the redox peaks and the mechanism including dimerization equilibria will be discussed below. Non-cyclic derivative 4T–phen–4T (2 D), which was previously characterized, can be directly compared to macrocycle 6 D with respect to the electrophoric systems.[10] The formation of a radical cation in 2 D (on one 4T unit) occurs at a somewhat higher potential, whereas the second oxidation to a radical cation pair (on each 4T unit) is observed at lower potentials (Table 2). These specific shifts of the oxidation potentials and different stabilization of the radical cations and dications, respectively, might correlate with ring strain in the macrocycles.

Redox properties of diyne macrocycles and influence of ring size

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E1 [V]

Redox properties of phen–9T macrocycle and influence of the bridging unit The time semi-derivative convoluted CV of phen–9T macrocycle 7 is shown in Figure 9 (right). Compared to the diyne macrocycles 6 D and 6 E, at first glance, the shape of the CV looks 9


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Full Paper quite similar, apart from an additional third one-electron transcharged dimer (7/7 + ·) is further oxidized to doubly oxidized difer wave. Thus, in total five redox waves (E1 = 0.18 V; E1’ = meric radical cation (7 + ·/7 + ·) at somewhat higher potential 0.34 V; E2’ = 0.63 V; E2 = 0.72 V; E3 = 0.88 V) were identified and (E1’ = 0.34 V) than monomer 7 due to the electron-withdrawing determination of the transferred electrons resulted in two oneeffect of the positive charge. In a parallel pathway, dimeric radelectron transfers for the waves at E1/E1’ and at E2’/E2, and ical cation (7 + ·/7 + ·) can be formed by dimerization of two a third for E3 (Table 2). Therefore, even stable radical trications monomeric radical cations 7 + · (C2). Stepwise further oxidation are formed from 7, which is quite typical for longer oligothioof dimer (7 + ·/7 + ·) at E2’ = 0.63 V leads to dimeric diradical trica[26] phenes. Compared to 6 D and 6 E, the first four oxidation potion (7 + ·/72 + ). tentials are shifted negatively by 100–200 mV. Despite similar Owing to Coulombic repulsion of the two charged macrocyring sizes of 7 and 6 D, we attribute this finding to extended cles, the dimeric trication should immediately dissociate into conjugation in 7 where a nonithiophene (9T) is present instead monomeric species 7 + · and 72 + (C3). At a potential of E2 = of two diyne-linked quaterthiophene moieties in 6 D. As a con0.72 V, the 9T radical cation unit in 7 + · is oxidized to the 9T disequence one can conclude that in the donor–acceptor macrocation 72 + and further transformed to the 9T radical trication cycle series 6 D to 6 E to 7, the donor strength is continuously 73 + · at E3 = 0.88 V. Temperature-dependent CV measurements increased. The assignment of the various redox processes in the CVs of the three macrocycles 6 D, 6 E, and 7 to the respective charged species is complex, because the electrochemical processes (E) are superimposed by chemical (C) association equilibria of charged monomeric to dimeric species, which was previously seen for purely thiophenic macrocycles.[21] We derive the following E–C mechanism for the novel phen– 9T macrocycle 7 as a representative example comprising electron transfer, aggregation, and deaggregation steps (Scheme 6) for the monomeric (M; left) and dimeric (D; right) species. Thus, first oxidation of neutral monomeric 7 at E1 = 0.18 V leads to 9T radical monocation 7 + ·. Compared to cyclo[10]thiophene, this first oxidation step is shifted to higher potential by 0.15 V due to the slightly reduced p system and the influence of the more electron-deficient phen moiety.[21] It is well known that planar oligothiophene radical cations can dimerize in temperature-dependent equilibria.[27] Therefore, we assume in the E– C–E mechanism that monomeric radical cations 7 + · partly associate with neutral macrocycles 7 to give dimeric radical cations (7/7 + ·) (C1). Mathematical analysis of the corresponding CV peaks gave an approximate ratio of monomeric to dimeric species Scheme 6. Schematic presentation for the stepwise oxidation (E1–E3), including monomer–dimer equilibria (C1–C3) of about 60:40. The singly of macrocycle 7 as an example. Blue parts of the macrocycles correspond to charged species. &

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Full Paper of 7 between room temperature and 90 8C consistently revealed a shift of the dimerization equilibria towards higher monomer concentrations with increasing temperature (not shown here). Apart from the third one-electron transfer (E3), the derived E–C mechanism for phen–9T 7 seems to be general and also applies for the diyne macrocycles 6 D and 6 E.

neutral one. In contrast, higher oxidation processes, including redox waves E3 and E4 (one electron transferred each), turned out to be more difficult in the catenated species than in the macrocycle (E2 and E2’) and potentials were slightly shifted positively (DE = 70–110 mV). This effect might come from the repulsion of the charged rings in the catenane, which cannot escape due to the interlocked structure. The same electrochemical behavior and trends were found for the other synthesized diyne–[2]catenanes (6 D)2 and (6 E)2 (Table 3). In accordance with the macrocyclic series 6 D to 6 E to 7, the potential for each electron-transfer step is gradually lowered when going from (6 D)2, comprising 4T units, to (6 E)2 with 5T units and to (7)2 with a 9T electrophore, indicating that p-conjugation and therefore the donor strength of the oligothiophene part increases throughout this series. The assignment of the various redox processes in the CV of (7)2 and derivation of a matching E–C–E mechanism is discussed in comparison to macrocycle 7 (Scheme 7). Because the oxidized rings in the [2]catenane tend towards planarity, notwithstanding internal stabilization, we cannot rule out dimerization equilibria of the charged species (C1–C4), which would superimpose the electrochemical processes (E1–E3), as in the E– C–E mechanism for the macrocycles (Scheme 6). Thus, we assign the first negatively shifted oxidation wave at E1 to the oxidation of (7)2 to radical cation (7)2 + ·, in which the positive charge in one ring can be internally stabilized by the oligothiophene p system in the other ring (Scheme 7, left). The dimerization of the radical cation (7)2 + · with neutral (7)2 to form dimeric catenane radical cation [(7)2 + ·/(7)2] is very likely (C1) and the corresponding electrochemical and chemical steps for dimers are shown on the right side of Figure 7. The second oxidation (E2/E2’) in the potential regime of 0.2–0.6 V eventually leads to the [2]catenane diradical dication + ·(7)2 + · and, because the redox wave is not sufficiently resolved, we assume that this species is formed either along the monomer channel by further oxidation of the monomeric radical cation (7)2 + · or by the dimer channel by going through successively oxidized dimers up to [(7)22 + ·/(7)22 + ·], which can all be in association/dissociation equilibria (C2–C4) with corresponding monomeric species. Further oxidation of dication +· (7)2 + · at E3 = 0.70 V and the transfer of the third electron leads to catenane radical trication + ·(7)22 + , in which one macrocycle in the [2]catenane carries a radical cation and the other a dication. The tetracationic species 2 + (7)22 + , in which both rings carry two charges and 9T dications are formed at E4 = 0.83 V by withdrawal of the forth electron from the catenane, corresponds to dication 72 + in the E–C–E mechanism of the macrocycles (Scheme 7). The E–C–E mechanisms of both the macrocycles and the [2]catenanes appear quite similar with respect to the charging of the individual rings and the involvement of typical dimerization equilibria. However, in the case of the catenanes, forced through-space interactions play a role and influence the redox behavior. Thus, the electrochemical characterization of the [2]catenanes revealed pronounced electronic interactions between the interlocked macrocycles and are more profound than the results of the optical measurements.

Redox properties of [2]catenanes and influence of topology The time semi-derivative convoluted CV of [2]catenane (7)2 is shown in Figure 10 as representative of all [2]catenanes presented herein and was recorded in the same potential regime as corresponding macrocycle 7.

Figure 10. Time semi-derivative convoluted cyclic voltammogram of phen– nonithiophene [2]catenane (7)2. Dotted vertical lines define regions with integer number of transferred electrons.

Four redox waves at E1 = 0.12 V, E2 = 0.27 V, E3 = 0.70 V, and E4 = 0.83 V are visible plus an additional smaller shoulder accompanying the second peak at E2’ = 0.37 V (Table 3). Determination of the number of transferred electrons revealed that four electrons are withdrawn in total, two in the range of 0.0– 0.6 V (E1–E2’) giving rise to stable radical cations 0(7)2 + · and diradical dications + ·(7)2 + ·, one between 0.6 and 0.8 V (E3) and the last at potentials > 0.8 V (E4), corresponding to the formation of radical trications + ·(7)22 + and tetracations 2 + (7)22 + , respectively (Scheme 7). The appearance of the catenane CV is different from that of macrocycle 7 and, due to the mechanically interlocked structure of the [2]catenane, additional electronic through-space interactions (attraction and repulsion) should be taken into account. In the potential regime up to 0.6 V, including redox waves E1–E2’ and two transferred electrons, the first wave is fully separated and slightly shifted to lower potential (DE = 60 mV). This is a consequence of the catenation allowing additional through-space stabilization of the resulting radical cation on one macrocycle by the proximity of the interlocked

Table 3. Oxidation potentials of [2]catenanes (6 D)2, (6 E)2, and (7)2.

(6 D)2 (6 E)2 (7)2

E1 [V]

E2/E2’ [V]

E3 [V]

E4 [V]

0.29 0.25* 0.12

0.44, 0.54 0.41*, 0.47 0.27, 0.37

0.75 0.72 0.70

0.89 ca. 0.80 ca. 0.83

*By splitting the wave at E = 0.33 V.

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Scheme 7. Schematic presentation for the stepwise oxidation (E1–E4) of [2]catenane (7)2 as a representative example. Blue parts of the macrocycles represent oxidized and charged units.

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Full Paper Conclusion

sprayed from THF/15 % water/1 % TFA solutions) instrument. Elemental analyses were performed with an Elementar Vario EL device. Thin-layer chromatography was carried out on aluminum plates, pre-coated with silica gel, Merck Si60 F254. Preparative column chromatography was performed in glass columns packed with silica gel, Merck Silica 60, particle size 40–63 mm. Optical measurements in solution were carried out in 1 cm cuvettes with Merck Uvasol grade solvents. Absorption spectra were recorded on a PerkinElmer Lambda 19 spectrometer and corrected fluorescence spectra were recorded on a PerkinElmer LS 55 fluorescence spectrometer. Cyclic voltammetry experiments were performed with a computer-controlled Autolab PGSTAT30 potentiostat in a three-electrode single-compartment cell with a platinum working electrode, a platinum wire counter electrode, and an Ag/AgCl reference electrode. All potentials were internally referenced to the ferrocene/ferricenium couple. Materials: Solvents and reagents were purchased from Aldrich, Merck and ABCR, unless otherwise stated, purified and dried by standard methods prior to use. 3,4-Diethylthiophene,[29] 2-pinacolborylthiophene,[30] 2,9-diiodophenanthroline,[11b] 2,9-di(thien-2-yl)1,10-phenanthroline,[10] 2,9-bis(5-iodothien-2-yl)-1,10-phenanthroline,[10] 2,9-dimesitylphenanthroline,[31] [1,3-bis(diphenylphosphino)propane]palladium(II) chloride,[32] tetrakis(acetonitrile) copper(I) tetrafluoroborate,[33] and oligothiophene building blocks C and E[34] were synthesized according to known literature procedures. N-Bromosuccinimide and thiophene were purchased from Merck. 2,5-Dibromothiophene and [1,3-bis(diphenylphosphino)propane]nickel(II)chloride were purchased from Aldrich.

Starting from a known strategy for the synthesis of conjugated macrocyclic systems,[10, 11] we improved this method and successfully extended it to the synthesis of “conjugated” topologies, such as donor–acceptor macrocycles and [2]catenanes based on electron-deficient phenanthroline and electron-rich oligothiophene moieties. The key step in these macrocyclization reactions is a Pd-catalyzed intramolecular Glaser-type coupling of terminal acetylene groups linked to oligothiophene building blocks. Syntheses of the complex donor–acceptor macrocycles 6 D, 6 E, and 7 and corresponding [2]catenanes (6 D)2, (6 E)2, and (7)2 were achieved. The systematic variation of the ring systems with respect to ring size, linkage (diyne vs. thiophene), and topology (macrocycle vs. catenane) resulted in two series of novel p-conjugated topological molecules. The various derivatives were investigated in great detail, analysed, and compared to each other with respect to their geometric and electronic structure. Despite the use of small ethyl substituents, 1H NMR investigation showed that dynamic rotation of the two interlocked macrocycles in the catenanes is hindered. Single crystal X-ray structure analysis of macrocycle 6 D revealed a rather flat ring, in which the circular curvature is mainly formed by syn-oriented thiophenes in the quaterthiophene units whereas the thiophenes adjacent to the phenanthroline unit are arranged in an anti fashion and tilted. Determination of the optical and redox behavior allowed rare insight into the influence of the various moieties in the macrocycles and catenanes on physical properties. In optical spectroscopy, absorption bands with lower energy S0 !S1 and higher energy S0 !S2 transitions were observed, which is typical for macrocycles in general and were also found for the [2]catenanes. A rather small topological influence on the optical spectra, due to electronic communication between the interlocked rings, was found. In contrast, the mutual throughspace interaction of the interlocked macrocycles in the [2]catenanes was more evident in the redox behavior determined by various electrochemical methods. In summary, unique series of conjugated donor–acceptor macrocycles and corresponding [2]catenanes have been prepared and investigated, elucidating the topological influence on structural and electronic properties.

Syntheses 1. Oligothiophenes 2-Bromo-3,4-diethylthiophene: 3,4-Diethylthiophene A’ (46.4 g, 0.33 mol) was dissolved in DMF (620 mL) and stirred with N-bromosuccinimide (58.7 g, 0.33 mol) at 0 8C for 3 h and warmed up to room temperature over 15 h. Aqueous workup furnished 2-bromo3,4-diethylthiophene (58 g, 80 %) as a colorless oil after purification by distillation. B.p. 116–117 8C (20 mm Hg); 1H NMR (400 MHz, CDCl3): d = 6.84 (t, 4J = 1 Hz, 1 H, H-5), 2.56 (q, 3J = 8 Hz, 2 H, -CH2), 2.54 (dq, 3J = 8 Hz, 4J = 1 Hz, 2 H, -CH2), 1.23 (t, 3J = 8 Hz, 3 H, -CH3), 1.09 ppm (t, 3J = 8 Hz, 3 H, -CH3); 13C NMR (CDCl3, 100 MHz): d = 143.2, 142.1, 119.5, 109.1, 22.8, 21.4, 13.8, 13.7 ppm; elemental analysis calcd (%) for C8H11BrS: C 43.85, H 5.06, S 14.63; found: C 44.12, H 4.97, S 14.80. 3,3’’,4,4’’-Tetraethyl-2,2’:5’,2’’-terthiophene (C): 2-Bromo-3,4-diethylthiophene (58 g, 0.26 mol) dissolved in diethyl ether (200 mL) was added to magnesium turnings (6.4 g, 0.27 mol) and heated at reflux for 1 h. After addition of 2,5-dibromothiophene (29.15 g, 0.12 mol) in diethyl ether (330 mL) the reaction mixture was heated at reflux in the presence of [Ni(dppp)Cl2] (0.3 g, 0.6 mmol; 0.5 mol) for 24 h. After work-up, terthiophene C (34.8 g, 80 %) was isolated as a greenish-yellow solid after recrystallization from petroleum ether at 20 8C. M.p. 47–48 8C; 1H NMR (400 MHz, CDCl3): d = 7.06 (s, 2 H, H-3’,4’), 6.88 (brs, 2 H, H-5,5’’), 2.76 (q, 3J = 8 Hz, 4 H, -CH2-), 2.60 (dq, 3J = 8 Hz, 4J = 1.0 Hz, 4 H, -CH2-), 1.29 (t, 3J = 8 Hz, 6 H, -CH3), 1.19 ppm (t, 3J = 8 Hz, 6 H, -CH3); 13C NMR (CDCl3, 100 MHz): d = 144.8, 140.0, 136.5, 130.8, 125.9, 118.6, 22.2, 22.8, 14.9, 13.8 ppm; EI-MS: 360 [M] + ; elemental analysis calcd (%) for C20H24S3 : C 66.62, H 6.71; found: C 66.56, H 6.72. 5,5’’-Dibromo-3,3’’,4,4’’-tetraethyl-2,2’:5’,2’’-terthiophene: Terthiophene C (1.80 g, 5 mmol) was dissolved in DMF (25 mL) and N-bromosuccinimide (1.78 g, 10 mmol) was added at room temperature.

Experimental Section Instruments and measurements: NMR spectra were recorded on Bruker Avance 400 and AMX 500 spectrometers. Chemical shift values (d) are expressed in parts per million using tetramethylsilane (1H NMR: dH = 0.00) or residual solvent protons (1H NMR: dH = 6.0 for C2D2Cl4, 5.36 for CD2Cl2, and 3.59/1.74 for THF; 13C NMR: dC = 77.0 for CDCl3, 73.78 for C2D2Cl4, 66.4/24.3 for THF, and 53.4 for CD2Cl2) as internal standards. The atom numbering used in NMR characterization is outlined. Mass spectra (cited as monoisotopic masses) were recorded with a Bruker Daltonics Reflex III, a Bruker Daltonik Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer solariX equipped with a 7.0 T superconducting magnet and interfaced to an Apollo II Dual ESI/MALDI source (MALDI-TOF; matrix: dithranol) and Waters-Micromass ZMD (ESI + , Chem. Eur. J. 2015, 21, 1 – 19

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Full Paper The product (2.36 g, 91 %) was isolated as a yellow solid after 15 h with stirring, aqueous workup, and purification by column chromatography on silica gel (eluent: petroleum ether). M.p. 90–91 8C; 1 H NMR (400 MHz, CDCl3): d = 7.03 (s, 2 H, H-3’,4’), 2.77 (q, 3J = 8 Hz, 4 H, -CH2-), 2.63 (q, 3J = 8 Hz, 4 H, -CH2-), 1.23 (t, 3J = 8 Hz, 6 H, -CH3), 1.20 ppm (t, 3J = 8 Hz, 6 H, -CH3); 13C NMR (100 MHz, CDCl3): d = 143.7, 140.1, 135.6, 130.6, 126.3, 108.6, 21.9, 21.6, 15.4, 14.1 ppm; MALDI-TOF MS: 516.0 [M] + ; elemental analysis calcd (%) for C20H22Br2S3 : C 46.34, H 4.28; found: C 46.50, H 4.35. 3’,3’’’,4’,4’’’-Tetraethyl-2,2’:5’,2’’:5’’,2’’’:5’’’,2’’’’-quinquethiophene (E): 5,5’’-Dibromo-3,3’’, 4,4’’-tetraethyl-2,2’:5’,2’’-terthiophene (2.1 g, 4.1 mmol), 2-pinacolborylthiophene (2.04 g, 9.7 mmol), tris(dibenzylidenacetone)dipalladium (chloroform adduct; 168.8 mg, 0.2 mmol) and tris-tert-butylphosphonium tetrafluoroborate (93.5 mg, 0.3 mmol) were dissolved in degassed THF (20 mL) under argon. After cooling to 0 8C, a degassed aqueous K3PO4 solution (32 mL, 32 mmol, 1.0 m) was added dropwise. The reaction mixture was stirred at 0 8C for 3 h and then quenched with a saturated NH4Cl solution. After extraction with dichloromethane (3 20 mL), the combined organic layers were washed with water (ca. 30 mL) and dried over Na2SO4. The solvent was removed and the residue was purified by column chromatography on silica gel (eluent: petroleum ether) and then recrystallized from THF/n-hexane to give E (2.1 g, 98 % yield) as a bright yellow solid. M.p. 112–113 8C; 1H NMR (400 MHz, CDCl3): d = 7.34 (dd, 3J = 5 Hz, 4J = 1 Hz, 2 H, H-5,5’’’’), 7.19 (dd, 3J = 4 Hz, 4J = 1 Hz, 2 H, H-3,3’’’’), 7.13 (s, 2 H, H-3’’,4’’), 7.10 (dd, 3J = 5 Hz, 3J = 4 Hz, 2 H, H-4,4’’’’), 2.86–2.76 (m, 8 H, H-a,a’), 1.30– 1.23 ppm (m, 12 H, H-b,b’); 13C NMR (100 MHz, CDCl3): d = 141.3, 141.2, 136.1, 135.9, 129.9, 129.7, 127.4, 126.0, 125.9, 125.4, 21.2, 21.0, 15.33, 15.31 ppm; MALDI-TOF MS: 524.4 [M] + ; elemental analysis calcd (%) for C28H28S5 : C 64.08, H 5.38; found: C 63.87, H 5.46.

dichloromethane (2 50 mL). The combined organic solutions were concentrated and the crude product filtered over silica with dichloromethane. 2 A was isolated (16.4 g, 92 %) as a pale yellow solid after recrystallization from ethanol. M.p. 154 8C; 1H NMR (400 MHz, CDCl3): d = 8.21 (d, 3J = 9 Hz, 2 H, PhenH-4), 7.99 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.86 (dd, 3J = 4 Hz, 4J = 1 Hz, 2 H, ThH-3), 7.70 (s, 2 H, PhenH-5), 7.54 (dd, 3J = 5 Hz, 4J = 1 Hz, 2 H, ThH-5), 7.20 ppm (dd, 3J = 5 Hz, 4J = 4 Hz, 2 H, ThH-4); 13C NMR (100 MHz, CDCl3): d = 152.5, 146.1, 145.7, 136.9, 129.0, 128.2, 127.9, 125.8, 125.75, 118.8 ppm; ESI-MS: 345 [M + H] + ; elemental analysis calcd (%) for C20H12N2S2 : C 69.74, H 3.51, N 8.13; found: C 69.43, H 3.55, N 8.09. 2,9-Bis(3’,4’-diethyl-2,2’-bithien-5-yl)-1,10-phenanthroline (2 B): 2 B was synthesized from 3 A (1.08 g, 1.8 mmol) in THF (10 mL), [Pd(PPh3)4] (70 mg, 0.06 mmol), 3,4-diethylthiophene A’ (0.56 g, 4.0 mmol) in THF (10 mL), n-butyllithium (2.52 mL, 4.0 mmol 1.6 m solution in hexanes) and dry ZnCl2 (0.60 g, 4.4 mmol) in THF (5 mL) according to GP1. After workup, the crude product was purified via recrystallization from n-hexane/THF to give compound 2 B (0.6 g, 54 %) as a pale yellow solid. M.p. 157–158 8C; 1H NMR (400 MHz, CDCl3): 8.21 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.98 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.78 (d, 3J = 4 Hz, 2 H, ThH-B), 7.71 (s, 2 H, PhenH-5), 7.20 (d, 3J = 4 Hz, 2 H, ThH-C), 6.93 (s, 2 H, ThH-D’), 2.84 (q, 3J = 8 Hz, 4 H, -CH2-), 2.61 (dq, 3J = 7 Hz, 4J = 1 Hz, 4 H, -CH2-), 1.32 (t, 3J = 8 Hz, 6 H, -CH3), 1.22 ppm (t, 3J = 7 Hz, 6 H, -CH3); 13C NMR (100 MHz, CDCl3): 152.2, 145.5, 145.2, 144.9, 140.6, 140.2, 136.7, 131.3, 127.8, 126.8, 125.9, 125.6, 118.9, 118.5, 22.3, 21.0, 15.0, 13.9 ppm; MALDITOF MS: 620.1 [M] + ; elemental analysis calcd (%) for C36H32N2S4 : C 69.64, H 5.19, N 4.51; found: C 69.49, H 5.21, N 4.48. 2,9-Bis(3,4,3’’,4’’-tetraethyl-2,2’:5’,2’’-terthien-5-yl)-1,10-phenanthroline (2 C): 2 C was synthesized from 2,9-diiodophenanthroline 1 (1.0 g, 2.3 mmol) in THF (10 mL), [Pd(PPh3)4] (270 mg, 0.23 mmol), terthiophene C (1.67 g, 4.6 mmol) in THF (20 mL), n-butyllithium (2.9 mL, 4.6 mmol, 1.6 m solution in hexanes) and dry ZnCl2 (0.69 g, 5.1 mmol) in THF (10 mL) according to GP1. After workup, the crude product was purified via recrystallization from n-hexane/THF to give 2 C (0.93 g, 45 %) as a yellow solid. M.p. 202–203 8C; 1 H NMR (400 MHz, CDCl3): 8.24 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.95 (d, 3 J = 9 Hz, 2 H, PhenH-3), 7.75 (s, 2 H, PhenH-5), 7.25 (d, 3J = 4 Hz, 2 H, ThH-B’), 7.11 (d, 3J = 4 Hz, 2 H, ThH-C’), 6.91 (s, 2 H, ThH-D’’), 3.41 (q, 3J = 8 Hz, 4 H, -CH2-), 2.92 (q, 3J = 8 Hz, 4 H, -CH2-), 2.80 (q, 3 J = 8 Hz, 4 H, -CH2-), 2.62 (q, 3J = 8 Hz, 4 H, -CH2-), 1.40–1.31 (m, 18 H, -CH3), 1.23 ppm (t, 3J = 8 Hz, 6 H, -CH3); 13C NMR (100 MHz, CDCl3): 153.3, 145.9, 144.9, 144.4, 141.8, 140.0, 137.5, 136.6, 136.5, 136.4, 132.7, 130.8, 127.2, 126.0, 125.9, 125.6, 121.3, 118.6, 73.9, 22.2, 21.4, 21.2, 20.9, 15.42, 15.40, 15.0, 13.8 ppm; MALDI-TOF: 897.4 [M] + ; elemental analysis calcd (%) for C52H52N2S6 : C 69.60, H 5.84, N 3.12; found: C 69.48, H 6.09, N 2.91.

2. Open-chained bis(oligothienyl)phenanthrolines General procedure 1 (GP1): Synthesis of oligothiophene–phenanthroline derivatives via Negishi coupling (Scheme 1): To a degassed solution of the oligothiophene (A’, C, or E) in THF was added n-butyllithium (1.6 m in n-hexane) at 78 8C. The mixture was stirred for 1 h and an additional 1 h without the cooling bath. A solution of vacuum-dried ZnCl2 in THF was then added to the reaction mixture at 78 8C and stirred for 0.5 h. The cooling bath was again removed and the solution stirred at ambient temperature for a further 0.5 h. This solution was then transferred to a degassed mixture of diiodinated phenanthroline derivative 1 or 3 A and Pd catalyst in THF at room temperature and stirred for 24 h. The reaction mixture was quenched with aqueous ammonia (12 %) and the aqueous phase was extracted twice with dichloromethane. The combined organic solutions were concentrated and the crude product filtered over silica with dichloromethane. The crude product was purified by recrystallization or column chromatography.

2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-2,2’:5,2’’:5’’,2’’’-quaterthien-5-yl)1,10-phenanthroline (2 D): 2 D was synthesized from 3 A (2.10 g, 3.52 mmol) in THF (20 mL), [Pd(PPh3)4] (0.20 g, 0.2 mmol), terthiophene C (2.54 g, 7.0 mmol) in THF (40 mL), n-butyllithium (4.43 mL, 7.1 mmol, 1.6 m solution in hexanes) and dry ZnCl2 (1.05 g, 7.7 mmol) in THF (8 mL) according to GP1. After workup, the crude product was purified via recrystallization from n-hexane/THF to give 2 D (2.10 g, 56 %) as an orange solid. M.p. 94–95 8C; 1H NMR (400 MHz, CDCl3): 8.21 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.99 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.78 (d, 3J = 4 Hz, 2 H, ThH-B), 7.71 (s, 2 H, PhenH-5), 7.24 (d, 3J = 4 Hz, 2 H, ThH-C), 7.12 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.06 (d, 3J = 4 Hz, 2 H, ThH-C’’), 6.89 (s, 2 H, ThH-D’’’), 2.90 (q, 3J = 8 Hz, 4 H, -CH2-), 2.76 (m, 8 H, -CH2-), 2.60 (q, 3J = 8 Hz, 4 H, -CH2-), 1.32– 1.27 (m, 12 H, -CH3), 1.24–1.18 ppm (m, 12 H, -CH3); 13C NMR (100 MHz, CDCl3): 152.2, 145.6, 145.4, 144.9, 142.1, 141.3, 140.2, 139.5, 136.7, 135.8, 130.7, 130.2, 130.1, 127.8, 126.9, 125.9, 125.6,

2,9-Di(2-thienyl)phenanthroline (2 A): To a degassed solution of thiophene (9.59 g, 0.11 mol) in THF (200 mL) was added n-butyllithium (72 mL, 0.12 mol, 1.6 m solution in hexanes) at 78 8C. The mixture was stirred at 78 8C for 1 h and additionally 1 h after removal of the cooling bath. Vacuum-dried ZnCl2 (17 g, 0.13 mol) dissolved in THF (130 mL) was added at 78 8C to the reaction mixture and stirred for 0.5 h. The cooling bath was removed again and the solution stirred under ambient condition for further 0.5 h. This solution was then transferred via cannula to a degassed mixture of 2,9-diiodophenanthroline (22.3 g, 52 mmol) and [Pd(PPh3)4] (2.98 g, 2.6 mmol, 5 mol %) in THF (100 mL) at room temperature and stirred for 24 h. The reaction mixture was quenched with aqueous ammonia (12 %) and the aqueous phase was extracted twice with

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Full Paper 118.7, 118.5, 22.2, 21.4, 21.2, 20.9, 15.5, 15,3, 15.0, 13.8 ppm; MALDI-TOF: 1061.3 [M + 1] + ; elemental analysis calcd (%) for C60H56N2S8 : C 67.88, H 5.32, N 2.64; found: C 67.95, H 5.31, N 2.58.

140.4, 139.0, 136.7, 136.4, 127.9, 127.1, 125.8, 125.7, 118.4, 74.2, 24.6, 21.9, 15.5, 14.6 ppm; MALDI-TOF MS: 872.1 [M] + ; elemental analysis calcd (%) for C36H30I2N2S4 : C 49.55, H 3.46, N 3.21; found: C 49.36, H 3.53, N 3.17.

2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-2,2’:5’,2’’:5’’,2’’’:5’’’,2’’’’-quinquethien-5-yl)-1,10-phenanthroline (2 E): 2 E was synthesized from 2,9-diiodophenanthroline 1 (0.81 g, 1.9 mmol) in THF (15 mL), [Pd(PPh3)4] (80 mg, 0.07 mmol), quinquethiophene E (2.00 g, 3.8 mmol) in THF (25 mL), n-butyllithium (2.40 mL, 3.8 mmol, 1.6 m solution in hexanes), dry ZnCl2 (0.57 g, 4.2 mmol) in THF (8 mL) according to GP1. After workup, the crude product was purified by SEC (eluent: THF) to give 2 E (0.45 g, 20 %) as an orange solid. M.p. 228–228.5 8C; 1H NMR (400 MHz, CDCl3): 8.24 (d, 3J = 8 Hz, 2 H, PhenH-4), 8.02 (d, 3J = 9 Hz, 2 H, PhenH-3), 7.81 (d, 3J = 4 Hz, 2 H, ThH-B), 7.73 (s, PhenH-5), 7.33 (dd, 3J = 5 Hz, 4J = 1 Hz, 2 H, ThHD’’’’), 7.27 (d, 3J = 4 Hz, 2 H, ThH-C), 7.18 (dd, 3J = 4 Hz, 4J = 1 Hz, 2 H, ThH-B’’’’), 7.15 (d, 3J = 4 Hz, 2 H, ThH-B’’’), 7.12 (d, 3J = 4 Hz, 2 H, ThH-C’’’), 7.09 (dd, 3J = 5 Hz, 3J = 5 Hz, 2 H, ThH-C’’’’), 2.93 (t, 3J = 7 Hz, 4 H, -CH2-), 2.85–2.75 (m, 12 H, -CH2-), 1.33–1.22 ppm (m, 24 H, -CH3); 13C NMR (100 MHz, CDCl3): 152.2, 145.4, 145.3, 142.1, 141.4, 141.3, 141.2, 139.6, 136.8, 136.0, 135.94, 135.91, 130.2, 130.1, 129.9, 129.7, 127.8, 127.4, 126.9, 126.0, 125.98, 125.9, 125.7, 125.4, 118.5, 21.4, 21.2, 21.1, 15.5, 15.4, 15.35, 15.3 ppm; MALDI-TOF MS: 1225.2 [M + 1] + ; elemental analysis calcd (%) for C68H60N2S10 : C 66.62, H 4.93; N 2.29; found: C 66.46, H 4.93, N 2.29.

2,9-Bis(3,4,3’’,4’’-tetraethyl-5’’-iodo-2,2’:5’,2’’-terthien-5-yl)-1,10phenanthroline (3 C): 3 C was synthesized from 2 C (0.30 g, 0.3 mmol) and N-iodosuccinimide (0.19 g, 0.8 mmol) according to GP2. After workup, the crude product was passed through a short pad of silica with dichloromethane and precipitated from methanol to give 3 C (0.37 g, 95 %) as a yellow solid. M.p. 160 8C; 1H NMR (400 MHz, CDCl3): 8.24 (d, 3J = 9 Hz, 2 H, PhenH-4), 7.95 (d, 3J = 9 Hz, 2 H, PhenH-3), 7.75 (s, 2 H, PhenH-5), 7.24 (d, 3J = 4 Hz, 2 H, ThH-B’), 7.05 (d, 3J = 4 Hz, 2 H, ThH-C’), 3.38 (q, 3J = 8 Hz, 4 H, -CH2-), 2.90 (q, 3 J = 8 Hz, 4 H, -CH2-), 2.84 (q, 3J = 7 Hz, 4 H, -CH2-), 2.62 (q, 3J = 8 Hz, 4 H, -CH2-), 1.38 (t, 3J = 8 Hz, 6 H, -CH3), 1.32 (t, 3J = 7 Hz, 6 H, -CH3), 1.23 (t, 3J = 8 Hz, 6 H, -CH3), 1.18 ppm (t, 3J = 8 Hz, 6 H, -CH3); 13 C NMR (100 MHz, CDCl3): 153.2, 148.5, 145.9, 144.3, 141.9, 139.8, 137.8, 137.1, 136.5, 136.0, 135.3, 132.5, 127.2, 126.4, 125.8, 125.6, 121.2, 24.6, 21.7, 21.4, 21.2, 15.5, 15.4, 14.4 ppm; MALDI-TOF: 1149.2 [M + 1] + ; elemental analysis calcd (%) for C52H50I2N2S6 : C 54.35, H 4.39, N 2.44; found: C 54.31, H 4.51, N 2.35. 2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-5’’’-iodo-2,2’:5,2’’:5’’,2’’’-quaterthien5-yl)-1,10-phenanthroline (3 D): 3 D was synthesized from 2 D (1.48 g, 1.4 mmol) and N-iodosuccinimide (0.79 g, 3.5 mmol) according to GP2. After workup, the crude product was passed through a short pad of silica with dichloromethane and crystallized from THF to give 3 D (1.8 g, 98 %) as a yellow solid. M.p. 238 8C; 1 H NMR (400 MHz, CDCl3): 8.22 (d, 3J = 8 Hz, 2 H, PhenH-4), 8.00 (d, 3 J = 8 Hz, 2 H, PhenH-3), 7.78 (d, 3J = 4 Hz, 2 H, ThH-B), 7.72 (s, 2 H, PhenH-5), 7.24 (d, 3J = 4 Hz, 2 H, ThH-C), 7.10 (d, 3J = 4 Hz, 2 H, ThHB’’), 7.02 (d, 3J = 4 Hz, 2 H, ThH-C’’), 2.89 (q, 3J = 8 Hz, 4 H, -CH2-), 2.83–2.73 (m, 8 H, -CH2-), 2.59 (q, 3J = 8 Hz, 4 H, -CH2-), 1.28 (t, 3J = 8 Hz, 6 H, -CH3), 1.23–1.18 (m, 12 H, -CH3), 1.14 ppm (t, 3J = 8 Hz, 6 H, -CH3); 13C NMR (100 MHz, CDCl3): 152.2, 148.5, 145.6, 145.4, 142.1, 141.4, 139.4, 136.7, 136.4, 135.4, 130.3, 129.8, 127.8, 127.0, 126.3, 125.9, 125.7, 118.5, 73.9, 24.6, 21.7, 21.4, 21.2, 15.49, 15.47, 15.3, 14.4 ppm; MALDI-TOF: 1313.2 [M + 1] + ; elemental analysis calcd (%) for C60H54I2N2S8 : C 54.87, H 4.14, N 2.13; found: C 54.92, H 4.19, N 2.05.

GP2: Iodination with N-iodosuccinimide (Schemes 1 and 2): To a solution of bis(oligothienyl)phenanthrolines 2 A–2 E (1 equiv) in chloroform/dichloromethane (1:1; 9 mL mmol1) and acetic acid (2 mL/40 mL solvent mixture), N-iodosuccinimide (NIS; 2 equiv) was added as solid at room temperature within 1 h. During 3 d with stirring at ambient temperature, three additional batches of NIS (0.2 equiv each) were added to the reaction mixture. The latter was poured into water, the phases were separated and the aqueous phase extracted twice with dichloromethane. The combined organic phases were washed with saturated NaHCO3 and dried over MgSO4. After removal of the solvent the crude product was purified either by column chromatography or filtration over a short silica pad. In case of precipitation of the product from reaction mixture it was filtered with suction, washed with water, saturated NaHCO3, water, and THF, and dried under vacuum. 2,9-Bis(5-iodo-2-thienyl)phenanthroline (3 A): To a solution of 2 A (1.54 g, 4.5 mmol) in chloroform/dichloromethane (1:1, 40 mL) and acetic acid (2 mL), N-iodosuccinimide (2.01 g, 8.9 mmol) was added at room temperature. During 3 d, three additional batches of NIS (0.2 equiv each) were added to the reaction mixture. The crude product was purified by column chromatography on silica gel (eluent: 2:3 petroleum ether/dichloromethane) to give 3 A (2.1 g, 79 %) as a yellow solid. M.p. 263 8C (decomp.); 1H NMR (400 MHz, CDCl3): d = 8.20 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.89 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.70 (s, 2 H, PhenH-5), 7.50 (d, 3J = 4 Hz, 2 H, ThH-B), 7.36 ppm (d, 3J = 4 Hz, 2 H, ThH-C); 13C NMR (100 MHz, CDCl3): d = 151.5, 145.7, 141.6, 138.3, 137.0, 128.2, 127.0, 126.0, 118.8, 78.6 ppm; ESI-MS: 597 [M + H] + ; elemental analysis calcd (%) for C20H10I2N2S2 : C 40.29, H 1.69, N 4.70; found: C 40.44, H 1.75, N 4.70.

2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-5’’’’-iodo-[2,2’:5’,2’’:5’’,2’’’:5’’’,2’’’’] quinquethien-5-yl)-1,10-phenanthroline (3 E): 3 E was synthesized from 2 E (0.40 g, 0.33 mmol) and N-iodosuccinimide (0.184 g, 0.82 mmol) according to GP2. The crude product precipitated and was isolated by filtration to give 3 E (0.36 g, 75 %) as a red solid. M.p. 248–249 8C; 1H NMR (400 MHz, C2D2Cl4): 8.33 (d, 3J = 9 Hz, 2 H, PhenH-4), 8.07 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.90 (d, 3J = 4 Hz, 2 H, ThH-B), 7.80 (s, 2 H, PhenH-5), 7.33 (d, 3J = 4 Hz, 2 H, ThH-C), 7.25 (d, 3 J = 4 Hz, 2 H, ThH-B’’’’), 7.17 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.14 (d, 3J = 4 Hz, 2 H, ThH-C’’), 6.87 (d, 3J = 4 Hz, 2 H, ThH-C’’’’), 2.92 (q, 3J = 8 Hz, 4 H, -CH2-), 2.81–2.72 (m, 12 H, -CH2-), 1.32 (t, 3J = 7 Hz, 6 H, -CH3), 1.29–1.22 ppm (m, 18 H, -CH3); 13C NMR (125 MHz, 330 K, C2D2Cl4): 142.5, 142.3, 142.1, 141.7, 141.4, 137.6, 136.1, 135.9, 130.4, 130.3, 130.1, 129.0, 128.0, 127.4, 127.2, 126.3, 126.2, 125.9, 123.8, 120.5, 119.1, 116.8, 116.6, 116.3, 73.0, 21.5, 21.4, 21.3, 21.2, 15.38, 15.35, 15.30 ppm; MALDI-TOF: 1477.5 [M + 1] + ; elemental analysis calcd (%) for C52H50I2N2S6·2H2O: C 53.96, H 4.13, N 1.85; found: C 53.64, H 3.92, N 1.90.

2,9-Bis(3’,4’-diethyl-5’-iodo-2,2’-bithien-5-yl)-1,10-phenanthroline (3 B): 3 B was synthesized from 2 B (0.50 g, 0.8 mmol) and N-iodosuccinimide (0.43 g, 1.9 mmol) according to GP2. After workup, the crude product was passed through a short pad of silica with dichloromethane to give 3 B (0.67 g, 96 %) as a yellow solid. M.p. 198–199 8C; 1H NMR (400 MHz, CDCl3): 8.21 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.98 (d, 3J = 9 Hz, 2 H, PhenH-3), 7.73 (d, 3J = 4 Hz, 2 H, ThH-B), 7.71 (s, 2 H, PhenH-5), 7.16 (d, 3J = 4 Hz, 2 H, ThH-C), 2.90 (q, 3 J = 8 Hz, 4 H, -CH2-), 2.62 (q, 3J = 8 Hz, -CH2-), 1.22–1.16 ppm (m, 12 H, -CH3); 13C NMR (100 MHz, CDCl3): 152.1, 148.6, 145.8, 145.5, Chem. Eur. J. 2015, 21, 1 – 19

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GP3: Sonogashira coupling (Scheme 2): The iodo derivative (3 B– 3 E) was dissolved in degassed mixture of pyridine/triethylamine (1:1 v/v; 28 mL mmol1l) in a pressure-resistant Schlenk tube to which [Pd(PPh3)2Cl2], CuI, PPh3, and trimethylsilylacetylene were added successively under inert gas. The sealed tube was heated at 70 8C whilst stirring for 6 h and cooled to room temperature. After

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Full Paper CDCl3): 8.24 (d, 3J = 8 Hz, 2 H, PhenH-4), 8.02 (d, 3J = 9 Hz, 2 H, PhenH-3), 7.81 (d, 3J = 4 Hz, 2 H, ThH-B), 7.73 (s, 2 H, PhenH-5), 7.27 (d, 3J = 4 Hz, 2 H, ThH-C), 7.19 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.14 (d, 3J = 4 Hz, 2 H, ThH-B’’’’), 7.12 (d, 3J = 4 Hz, 2 H, ThH-C’’’’), 7.01 (d, 3J = 4 Hz, 2 H, ThH-C’’), 2.92 (q, 3J = 8 Hz, 4 H, -CH2-), 2.83–2.76 (m, 12 H, -CH2-), 1.31 (t, 3J = 7 Hz, 6 H, -CH3), 1.27–1.22 (m, 18 H, -CH3), 0.29 ppm (s, 18 H, H-SiMe3); 13C NMR (100 MHz, CDCl3): 152.2, 145.6, 145.4, 142.1, 141.9, 141.40, 141.36, 139.5, 137.7, 136.7, 136.1, 135.6, 133.1, 130.3, 130.2, 130.0, 129.3, 127.9, 127.0, 126.2, 126.0, 125.9, 125.7, 125.3, 122.6, 118.5, 100.1, 97.4, 21.4, 21.23, 21.17, 15.5, 15.3, 15.2, 0.1 ppm; MALDI-TOF MS: 1417.8 [M + H] + ; elemental analysis calcd (%) for C78H76N2S10Si2 : C 66.05, H 5.40, N 1.98; found: C 65.82, H 5.63, N 1.75.

evaporation of the solvent, the residue was filtered through a short silica column with dichloromethane and purified by precipitation or column chromatography. 2,9-Bis(3’,4’-diethyl-5’-trimethylsilylethinyl-2,2’-bithien-5-yl)-1,10phenanthroline (4 B): 4 B was synthesized from 3 B (0.5 g, 0.6 mmol), [Pd(PPh3)2Cl2] (21 mg, 0.03 mmol), CuI (10.7 mg, 0.06 mmol), PPh3 (14.8 mg, 0.06 mmol), and trimethylsilylacetylene (0.32 mL, 2.3 mmol) according to GP3. After workup, the crude product was precipitated from methanol. 4 B (0.45 g, 97 %) was obtained as a yellow solid. M.p. 240 8C; 1H NMR (400 MHz, CDCl3): d = 8.21 (d, 3J = 9 Hz, 2 H, PhenH-4), 7.98 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.75 (d, 3J = 4 Hz, 2 H, ThH-B), 7.71 (s, 2 H, PhenH-5), 7.20 (d, 3J = 4 Hz, 2 H, ThH-C), 2.82 (q, 3J = 8 Hz, 4 H, H-CH2), 2.71 (q, 3J = 8 Hz, HCH2), 1.24 (t, 3J = 8 Hz, 6 H, H-CH3), 1.18 (t, 3J = 8 Hz, 6 H, H-CH3), 0.27 ppm (s, 18 H, H-SiMe3); 13C NMR (100 MHz, CDCl3): d = 152.1, 150.7, 145.8, 145.5, 140.3, 139.1, 136.7, 132.0, 127.9, 127.4, 125.8, 125.7, 118.5, 117.4, 102.0, 97.6, 21.9, 21.3, 15.3, 14.6, 0.0 ppm; MALDI-TOF MS: 813.4 [M + H] + ; elemental analysis calcd (%) for C46H48N2S4Si2 : C 67.93, H 5.95, N 3.44; found: C 67.87, H 5.95, N 3.29.

GP4: Cleavage of the protecting group (Scheme 2): To a solution of TMS-protected bisacetylene derivative (4 C–4 E) in THF/MeOH mixture (4:1 v/v; 125 mL mmol1l), CsF was added and the resultant mixture was stirred at room temperature for 2 h. After evaporation of the solvent at room temperature, the residue was filtered through a short silica column with dichloromethane to give the deprotected product. Products 5 C–5 E were used without further purification.

2,9-Bis(3,4,3’’,4’’-tetraethyl-5’’-trimethylsilylethinyl-2,2’:5’,2’’-terthien-5-yl)-1,10-phenanthroline (4 C): 4 C was synthesized from 3 C (0.30 g, 0.26 mmol), [Pd(PPh3)2Cl2] (10 mg, 0.01 mmol), CuI (5 mg, 0.03 mmol), PPh3 (8 mg, 0.03 mmol), and trimethylsilylacetylene (0.16 mL, 1.1 mmol) according to GP3. After workup, the crude product was precipitated from methanol to give 4 C (0.23 g, 82 %) as a yellow solid. M.p. 181–182 8C; 1H NMR (400 MHz, CDCl3): 8.21 (d, 3J = 9 Hz, 2 H, PhenH-4), 7.98 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.755 (d, 3J = 4 Hz, 2 H, ThH-B), 7.71 (s, 2 H, PhenH-5), 7.20 (d, 3J = 4 Hz, 2 H, ThH-C), 2.82 (q, 3J = 8 Hz, 4 H, -CH2-), 2.71 (q, 3J = 8 Hz, -CH2-), 1.24 (t, 3J = 8 Hz, 6 H, -CH3), 1.18 (t, 3J = 8 Hz, 6 H, -CH3), 0.27 ppm (s, 18 H, H-SiMe3); 13C NMR (100 MHz, CDCl3): 153.2, 150.7, 144.6, 142.1, 139.5, 137.5, 137.0, 136.7, 135.7, 132.6, 131.7, 127.3, 126.4, 126.0, 125.9, 125.7, 121.4, 117.1, 102.0, 97.6, 22.0, 21.5, 21.3, 21.2, 15.5, 15.4, 15.3, 14.6, 0.1 ppm; MALDI-TOF MS: 1089.4 [M + H] + ; elemental analysis calcd (%) for C62H68N2S6Si2·2H2O: C 66.14, H 6.45, N 2.49; found: C 66.20, H 6.12, N 2.36.

2,9-Bis(3’,4’-diethyl-5’-ethinyl-2,2’-bithien-5-yl)-1,10-phenanthroline (5 D): 5 D was synthesized according to GP4 starting from TMS-protected 4 D (0.1 g, 0.08 mmol) in THF/MeOH (4:1 v/v; 10 mL) and CsF (40 mg, 0.26 mmol). The product (85.5 mg, 96 %) was isolated as a red solid.[35] 1H NMR (400 MHz, CDCl3): d = 8.22 (d, 3 J = 9 Hz, 2 H, PhenH-4), 8.00 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.78 (d, 3 J = 4 Hz, 2 H, ThH-B), 7.72 (s, 2 H, PhenH-5), 7.26 (d, 3J = 4 Hz, 2 H, ThH-C), 7.12 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.09 (d, 3J = 4 Hz, 2 H, ThHC’’), 3.51 (s, 2 H, H-C CH), 2.90 (d, 3J = 8 Hz, 4 H, -CH2-), 2.79–2.68 (m, 12 H, -CH2-), 1.28 (t, 3J = 8 Hz, 6 H, H-CH3), 1.24–1.87 ppm (m, 18 H, H-CH3).

3. Oligothienyl–phenanthroline [2]catenanes, macrocycles, and [2]catenates

2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-5’’’-trimethylsilylethinyl2,2’:5,2’’:5’’,2’’’-quaterthien-5-yl)-1,10-phenanthroline (4 D): 4 D was synthesized from 3 D (1.00 g, 0.8 mmol), [Pd(PPh3)2Cl2] (26 mg, 0.04 mmol), CuI (15 mg, 0.08 mmol), PPh3 (20 mg, 0.08 mmol), and trimethylsilylacetylene (0.44 mL, 3.1 mmol) according to GP3. After workup, the crude product was crystallized from methanol/THF to give 4 D (0.93 g, 97 %) as an orange solid. M.p. 207–208 8C; 1H NMR (400 MHz, CDCl3): 8.22 (d, 3J = 8 Hz, 2 H, PhenH-4), 8.00 (d, 3J = 9 Hz, 2 H, PhenH-3), 7.78 (d, 3J = 4 Hz, 2 H, ThH-B), 7.72 (s, 2 H, PhenH-5), 7.24 (d, 3J = 4 Hz, 2 H, ThH-C), 7.10 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.08 (d, 3J = 4 Hz, 2 H, ThH-C’’), 2.90 (q, 3J = 8 Hz, 4 H, -CH2-), 2.79–2.66 (m, 12 H, -CH2-), 1.28 (t, 3J = 7 Hz, 6 H, -CH3), 1.24–1.17 (m, 18 H, -CH3), 0.26 ppm (s, 18 H, H-SiMe3); 13C NMR (100 MHz, CDCl3): 152.2, 150.6, 145.6, 145.5, 142.1, 141.4, 139.5, 139.4, 136.7, 136.3, 135.6, 131.6, 130.4, 129.8, 127.8, 127.0, 126.3, 126.0, 125.9, 125.7, 118.5, 117.1, 102.0, 97.5, 21.9, 21.4, 21.2, 21.1, 15.5, 15.3, 15.2, 14.6, 0.0 ppm; MALDI-TOF:1253.5 [M + H] + ; elemental analysis calcd (%) for C70H72N2S8Si2 : C 67.04, H 5.79, N 2.23; found: C 67.04, H 5.77, N 2.11.

GP5: Pd-catalyzed acetylene coupling under macrocycle and catenane formation (Scheme 2): To a solution of the bisacetylene intermediate 5 C–5 E in dichloromethane was added [Cu(CH3CN)4]BF4. After stirring for 0.5 h, the resultant red solution was transferred to a solution of [Pd(dppp)Cl2], CuI, TMEDA, and ethyl bromoacetate in degassed CH2Cl2 (250 mL per mmol 5 C–5 E) via syringe at room temperature. After 4 d stirring at ambient temperature, the solvent was removed under reduced pressure and the residue filtered through a short silica column with CH2Cl2/ CH3OH (10:1). The crude CuI catenate was redissolved in dichloromethane (250 mL per mmol starting material) together with some droplets of water, to which KCN (1.9 mmol per mmol starting material) was added. The solution was stirred for 1 h, washed with water, and dried over Na2SO4. The crude product was purified by SEC (eluent: tetrahydrofuran). [2]Catenane (6 D)2 : Starting from 4 D (0.1 g, 0.08 mmol) and deprotection according to GP4, the diacetylene intermediate 5 D was treated according to GP5 with [Cu(CH3CN)4]BF4 (13 mg, 41 mmol) in dichloromethane (20 mL) to give the copper complex [Cu(5 D)2]BF4. 1 H NMR(400 MHz, CDCl3): d = 8.42 (d, 3J = 8 Hz, 4 H), 8.00 (d, 3J = 9 Hz, 4 H), 7.79 (s, 4 H), 7.38 (d, 3J = 4 Hz, 4 H), 7.14 (d, 3J = 4 Hz, 4 H), 6.98 (d, 3J = 4 Hz, 4 H), 6.62 (d, 3J = 4 Hz, 4 H), 3.55 (s, 4 H), 2.83–2.72 (m, 24 H), 2.66 (q, 3J = 7 Hz, 8 H), 1.28–1.24 (m, 24 H), 1.16 (t, 3J = 7 Hz, 12 H), 0.91 ppm (t, 3J = 7 Hz, 12 H)]. [Cu(5 D)2]BF4 was in turn treated with a solution of [Pd(dppp)Cl2] (4.8 mg, 8 mmol), CuI (1.5 mg, 8 mmol), TMEDA (24 mL, 16 mmol), and ethyl bromoacetate (10.8 mL, 98 mmol) in dichloromethane, followed by KCN (10 mg,

2,9-Bis(3’,4’,3’’’,4’’’-tetraethyl-5’’’’-trimethylsilylethinyl2,2’:5’,2’’:5’’,2’’’:5’’’,2’’’’-quinquethien-5-yl)-1,10-phenanthroline (4 E): 4 E was synthesized from 3 E (0.3 g, 0.20 mmol), Pd (PPh3)2Cl2 (7 mg, 0.01 mmol), CuI (4 mg, 0.02 mmol), PPh3 (5 mg, 0.02 mmol), and trimethylsilylacetylene (0.12 mL, 0.8 mmol) according to GP3. After workup, the crude product was purified by column chromatography on silica gel (eluent: 1:2 THF/petroleum ether) to give 4 E (0.13 g, 46 %) as a red solid. M.p. 205–206 8C; 1H NMR (400 MHz,

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Full Paper 0.15 mmol) to effect decomplexation. The product (6 D)2 (42 mg, 47 %) was obtained as a red solid; macrocycle 6 D (15 mg, 16 %) was also isolated from a different chromatographic fraction as a red solid. (6 D)2[35]: 1H NMR (500 MHz, C2D2Cl4, 360 K): d = 8.28 (d, 3 J = 4 Hz, 4 H, ThH-B), 8.19 (d, 3J = 8 Hz, 4 H, PhenH-4), 7.90 (d, 3J = 8 Hz, 4 H, PhenH-3), 7.64 (s, 4 H, PhenH-5), 7.26 (d, 3J = 4 Hz, 4 H, ThH-C), 7.18–7.17 (m, 8 H, ThH-B’’,C’’), 2.95 (q, 3J = 8 Hz, 8 H, ThH-a), 2.92–2.66 (m, 32 H, 16 H, -CH2-), 2.75 (q, 3J = 8 Hz, 8 H, -CH2-), 1.32– 1.23 ppm (m, 48 H, H-CH3); 13C NMR (C2D2Cl4), 125 MHz): d = 151.6, 148.3, 145.9, 143.5, 141.4, 141.2, 138.9, 138.0, 137.1, 136.9, 136.0, 135.3, 131.2, 129.7, 129.0, 128.3, 127.8, 125.6, 124.9, 124.5, 119.7, 117.0, 84.2, 83.0, 22.6, 21.6, 21.32, 21.26, 15.5, 15.4, 15.1, 15.0 ppm; MALDI-TOF MS: 2212.2 [M] + ; HRMS calcd for [M] + : 2212.40998; found: 2212.40996.

calcd (%) for C64H54N2S8·H2O: C 68.29, H 5.01, N 2.49; found: C 68.11, H 4.97, N 2.45. Macrocycle 6 E: Starting from TMS-protected phenanthroline 4 E (23 mg, 0.016 mmol), the corresponding deprotected compound 5 E was generated according to GP4. Macrocycle 6 E was synthesized from 5 E by treatment according to GP5 with 2,9-dimesitylphenanthroline (6.7 mg, 0.016 mmol), [Cu(CH3CN)4]BF4 (5.0 mg, 0.16 mmol), [Pd(dppp)Cl2] (0.96 mg, 2 mmol), CuI (3 mg, 2 mmol), TMEDA (4.8 mL, 0.03 mmol), ethyl bromoacetate (2.2 mL, 0.02 mmol), and KCN (5 mg, 0.08 mmol). The resulting mixture was filtered and washed with water (ca. 10 mL) and a minimum amount of tetrahydrofuran. 6 E (10 mg, 48 %) was obtained as a red solid.[35] 1H NMR (500 MHz, C2D2Cl4): 8.30 (d, 3J = 4 Hz, 2 H, ThH-B), 8.28 (d, 3J = 9 Hz, 2 H, PhenH-4), 8.01 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.78 (s, 4 H, PhenH-5), 7.44 (d, 3J = 4 Hz, 2 H, ThH-C), 7.26–7.25 (m, 4 H, ThH-B’’,B’’’’), 7.22 (d, 3J = 4 Hz, 2 H, ThH-C’’), 7.10 (d, 3J = 4 Hz, 2 H, ThH-C’’’’), 3.06 (q, 3J = 7 Hz, 4 H, -CH2-), 2.89 (q, 3 J = 8 Hz, 4 H, -CH2-), 2.85–2.80 (m, 8 H, -CH2-), 1.42 (t, 3J = 7 Hz, 6 H, -CH3), 1.37 (t, 3J = 7 Hz, 6 H, -CH3), 1.34–1.29 ppm (m, 12 H, -CH3); MALDI-TOF MS: 1271.2 [M + H] + ; HRMS calcd for [M] + : 1270.18072; found: 1270.17978.

[2]Catenane (6 E)2 : Starting from 4 E (57 mg, 0.04 mmol), the corresponding deprotected 5 E was generated according to GP4. (6 E)2 was synthesized from 5 E by treatment according to GP5 with [Cu(CH3CN)4]BF4 (6.5 mg, 0.02 mmol), [Pd(dppp)Cl2] (2.4 mg, 4 mmol), CuI (0.75 mg, 4 mmol), TMEDA (1.2 mL, 8 mmol), ethyl bromoacetate (5.4 mL, 0.05 mmol), and KCN (5 mg, 0.08 mmol). The crude product was purified by SEC (eluent: tetrahydrofuran). [2]Catenane (6 E)2 (15 mg, 30 %) was obtained as a red solid together with macrocycle 6 E (5 mg, 10 %). (6 E)2[35] 1H NMR (400 MHz, [D8]THF): 8.33 (d, 3J = 4 Hz, 4 H, ThH-B), 8.17 (d, 3J = 8 Hz, 4 H, PhenH-4), 7.84 (d, 3J = 8 Hz, 4 H, PhenH-3), 7.66 (s, 4 H, PhenH-5), 7.31 (d, 3J = 4 Hz, 4 H, ThH-C), 7.28 (d, 3J = 4 Hz, 4 H, ThH-B’’), 7.26 (d, 3J = 4 Hz, 4 H, ThH-B’’’’), 7.24 (d, 3J = 4 Hz, 4 H, ThH-C’’), 7.08 (d, 3 J = 4 Hz, 2 H, ThH-C’’’’), 3.05 (q, 3J = 7 Hz, 8 H, -CH2-), 2.90 (q, 3J = 8 Hz, 8 H, -CH2-), 2.82–2.74 (m, 16 H, -CH2-), 1.38 (t, 3J = 8 Hz, 12 H, -CH3), 1.32 (t, 3J = 8 Hz, 12 H, -CH3), 1.26–1.17 (m, 24 H, -CH3); 1 H NMR (500 MHz, C2D2Cl4): 8.45 (d, 3J = 4 Hz, 4 H, ThH-B), 8.20 (d, 3 J = 9 Hz, 4 H, PhenH-4), 7.91 (d, 3J = 8 Hz, 4 H, PhenH-3), 7.70 (s, 4 H, PhenH-5), 7.37 (d, 3J = 4 Hz, 4 H, ThH-C), 7.24 (d, 3J = 4 Hz, 4 H, ThH-B’’’’), 7.20 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.15 (d, 3J = 4 Hz, 4 H, ThHC’’), 6.99 (d, 3J = 4 Hz, 4 H, ThH-C’’’’), 3.04 (q, 3J = 7 Hz, 8 H, -CH2-), 2.86 (q, 3J = 7 Hz, 8 H, -CH2-), 2.76 (q, 3J = 7 Hz, 8 H, -CH2-), 2.69 (q, 3 J = 7 Hz, 8 H, -CH2-), 1.43 (t, 3J = 8 Hz, 12 H, -CH3), 1.35 (t, 3J = 7 Hz, 12 H, -CH3), 1.29–1.23 ppm (m, 24 H, -CH3); 13C NMR (125 MHz, C2D2Cl4): 151.1, 146.1, 143.6, 141.8, 141.4, 141.3, 141.2, 141.0, 137.1, 136.3, 136.2, 136.1, 133.3, 131.2, 131.0, 129.3, 129.1, 127.9, 127.7, 127.3, 125.7, 125.4, 125.1, 123.3, 120.5, 119.1, 79.9, 78.7, 21.3, 21.0, 20.8, 20.8, 14.8, 14.6, 14.3, 14.1 ppm; MALDI-TOF MS: 2540.6 [M] + ; HRMS calcd for [M] + 2540.36986; found: 2540.36707.

[2]Catenate [Cu(6 C)2]BF4 : Starting from TMS-protected 4 C (54.5 mg, 0.05 mmol), the corresponding deprotected product 5 C was generated according to GP4. [Cu(6 C)2]BF4 was synthesized from 5 C by treatment according to GP5 with [Cu(CH3CN)4]BF4 (7.9 mg, 0.03 mmol), [Pd(dppp)Cl2] (2.9 mg, 5 mmol), CuI (0.95 mg, 5 mmol), TMEDA (2.0 mL, 13 mmol), and ethyl bromoacetate (6.8 mL, 0.06 mmol). The resulting product was treated with saturated aqueous KBF4 solution (ca. 20 mL) to perform an anion exchange. The product was further purified by column chromatography on silica gel (eluent: 10:1 CH2Cl2/CH3OH). The [2]catenate [Cu(6 C)2]BF4 (10 mg, 20 %) was obtained as a dark red solid.[35] 1H NMR (400 MHz, CDCl3): 8.72 (d, 3J = 8 Hz, 4 H, PhenH-4), 8.36 (s, 4, PhenH-5), 7.94 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.00 (d, 3J = 4 Hz, 4 H, ThH-B), 6.89 (d, 3J = 4 Hz, 4 H, ThH-C), 2.75–2.67 (m, 16 H, -CH2-), 2.47–2.37 (m, 16 H, -CH2-), 1.35 (t, 3J = 8 Hz, 12 H, -CH3), 1.23 (t, 3J = 8 Hz, 12 H, -CH3), 0.92–0.85 ppm (m, 24 H, -CH3); 13C NMR (125 MHz, CDCl3): 152.2, 146.0, 144.2, 143.9, 141.3, 139.4, 137.3, 136.9, 135.22, 135.18, 135.1, 131.6, 129.1, 128.1, 127.7, 127.1, 124.0, 116.8, 90.4, 86.9, 22.6, 21.3, 21.0, 20.7, 15.1, 14.9, 14.8, 14.6 ppm; MALDI-TOF MS: 1947.1 [MBF4] + ; HRMS calcd for [MBF4] + 1947.3887; found: 1947.39001. [2]Catenate [Cu(6 D)2]·BF4 : [2]Catenane (6 D)2 (12 mg, 5.4 mmol) was dissolved in degassed CH2Cl2 (ca. 8 mL) and [Cu(CH3CN)4]BF4 (3.4 mg, 11 mmol) was added. The resulting solution was washed with water (2 3 mL), and dried over Na2SO4. After removal of the solvent by evaporation, [2]catenate [Cu(6 D)2]BF4 (12 mg, 95 %) was obtained as a dark red solid.[35] 1H NMR (400 MHz, CDCl3): d = 8.63 (d, 3J = 8 Hz, 4 H, PhenH-4), 8.18 (s, 4 H, PhenH-5), 8.04 (d, 3J = 8 Hz, 4 H, PhenH-3), 7.54 (d, 3J = 4 Hz, 4 H, ThH-B), 7.20 (d, 3J = 4 Hz, 4 H, ThH-B’’), 7.28 (d, 3J = 4 Hz, 4 H, ThH-C’’), 7.28 (d, 3J = 4 Hz, 4 H, ThHC), 2.83 (q, 3J = 8 Hz, -CH2-), 2.78–2.73 (m, 32 H, -CH2-), 2.65 (q, 3J = 8 Hz, 8 H, -CH3), 1.35–1.25 ppm (m, 48 H, -CH3); 13C NMR (125 MHz, CD2Cl2): d = 150.4, 149.0, 143.7, 142.4, 141.5, 140.9, 139.7, 139.3, 137.7, 136.4, 136.1, 134.7, 130.2, 129.1, 128.9, 128.8, 126.9, 126.1, 125.4, 124.8, 124.5, 116.6, 83.5, 82.4, 22.4, 21.0, 14.90, 14.88, 14.7, 14.5 ppm; HRMS calcd for [M + HBF4] + : 2276.3474; found: 2276.3448.

Macrocycle 6 D: Bis(oligothienyl)phenanthroline 5 D (88 mg, 79 mmol) was dissolved in degassed dichloromethane (10 mL) and [Cu(CH3CN)4]BF4 (12.6 mg, 0.04 mmol) was added. After removal of dichloromethane by evaporation under reduced pressure, pyridine (40 mL), CuCl (16 mg, 0.16 mmol), and Cu(OAc)2·H2O (32 mg, 0.16 mmol) were added successively and stirred at room temperature for 3 d; resulting in formation of a red precipitate. The reaction mixture was cooled to 20 8C, filtered, washed with cold pyridine and chloroform (2 mL each) and dried under high vacuum at 60 8C. Macrocyle 6 D (68 mg, 78 %) was isolated as a red solid.[35] 1 H NMR (500 MHz, CDCl2CDCl2, 360 K): 8.36 (d, 3J = 4 Hz, 2 H, ThHB), 8.26 (d, 3J = 8 Hz, 2 H, PhenH-4), 7.94 (d, 3J = 8 Hz, 2 H, PhenH-3), 7.76 (s, 2 H, PhenH-5), 7.48 (d, 3J = 4 Hz, 2 H, ThH-C), 7.24 (d, 3J = 4 Hz, 2 H, ThH-B’’), 7.22 (d, 3J = 4 Hz, 2 H, ThH-C’’), 2.99 (q, 3J = 7 Hz, 4 H, -CH2-), 2.92–2.84 (m, 8 H, -CH2-), 2.76 (q, 3J = 7 Hz, 4 H, -CH3), 1.44–1.33 ppm (m, 24 H, -CH3); 13C NMR (125 MHz, CDCl2CDCl2, 360 K): 152.0, 148.0, 146.3, 144.1, 141.7, 141.4, 139.1, 138.4, 137.3, 136.7, 136.5, 135.4, 131.3, 129.9, 128.7, 128.6, 128.0, 125.7, 125.0, 124.3, 119.6, 117.4, 84.2, 83.1, 22.5, 21.4, 21.2, 21.1, 15.2, 14.9, 14.8, 14.5 ppm; MALDI-TOF MS: 1107.1 [M + H] + ; elemental analysis Chem. Eur. J. 2015, 21, 1 – 19

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4. Conversion of diacetylene bridges into thiophenes Macrocycle (7): To a mixture of compound 6 D (20 mg, 18 mmol) and Na2S (14 mg, 0.2 mmol) was added DMF (5 mL) and 2-meth-

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Full Paper oxyethanol (5 mL). The resultant mixture was heated at 120 8C for 2 h under argon. The solvent was removed by evaporation. The residue was extracted with dichloromethane (2 5 mL) and washed with water (5 3 mL). Purification was accomplished by column chromatography on silica gel (eluent: 1:2 THF/petroleum ether). Macrocycle 7 (8 mg, 38 %) was obtained as a red solid.[35] 1H NMR (500 MHz, CD2Cl2): 8.33 (d, 3J = 10 Hz, 2 H, PhenH-4), 8.10 (d, 3J = 5 Hz, 2 H, ThH-B), 8.05 (d, 3J = 11 Hz, 2 H, PhenH-3), 7.82 (s, 2 H, PhenH-5), 7.36 (d, 3J = 5 Hz, 2 H, ThH-C), 7.22 (d, 3J = 4 Hz, 2 H, ThHB’’’), 7.21 (s, 2 H, ThH-B’’’’’), 7.20 (d, 3J = 4 Hz, 2 H, ThH-C’’’), 2.94– 2.81 (m, 16 H, -CH2-), 1.37–1.29 ppm (m, 24 H, -CH3); 13C NMR (125 MHz, CDCl2CDCl2): 150.2, 145.8, 144.1, 142.2, 141.6, 141.1, 141.0, 138.5, 137.2, 137.0, 136.2, 135.5, 130.6, 130.3, 129.92, 129.87, 128.7, 128.13, 128.08, 126.0, 125.9, 124.1, 124.0, 119.8, 24.6, 23.9, 23.1, 21.4, 15.5, 15.3, 15.1, 15.0 ppm; MALDI-TOF MS: 1141.2 [M + H] + ; HRMS calcd for [M] + : 1140.19244; found: 1140.19208.

[7] J. E. Beves, B. A. Blight, C. J. Campbell, D. A. Leigh, R. T. McBurney, Angew. Chem. Int. Ed. 2011, 50, 9260; Angew. Chem. 2011, 123, 9428. [8] T. Ikeda, J. F. Stoddart, Sci. Technol. Adv. Mater. 2008, 9, 014104. [9] a) J.-P. Sauvage, Acc. Chem. Res. 1998, 31, 611; b) M. C. Jimnez, C. Dietrich-Buchecker, J.-P. Sauvage, Angew. Chem. Int. Ed. 2000, 39, 3284; Angew. Chem. 2000, 112, 3422; c) J.-P. Collin, C. Dietrich-Buchecker, P. GaviÇa, M. C. Jimnez-Molero, J.-P. Sauvage, Acc. Chem. Res. 2001, 34, 477; d) M. C. Jimnez-Molero, C. Dietrich-Buchecker, J.-P. Sauvage, Chem. Eur. J. 2002, 8, 1456; e) S. Bonnet, J.-P. Collin, M. Koizumi, P. Mobian, J.-P. Sauvage, Adv. Mater. 2006, 18, 1239; f) B. Champin, P. Mobian, J.-P. Sauvage, Chem. Soc. Rev. 2007, 36, 358; g) E. R. Kay, D. A. Leigh, F. Zerbetto, Angew. Chem. Int. Ed. 2007, 46, 72; Angew. Chem. 2007, 119, 72; h) S. Durot, F. Reviriego, J.-P. Sauvage, Dalton Trans. 2010, 39, 10557. [10] P. Buerle, M. Ammann, M. Wilde, G. Gçtz, E. Mena-Osteritz, A. Rang, C. A. Schalley, Angew. Chem. Int. Ed. 2007, 46, 363; Angew. Chem. 2007, 119, 367. [11] a) M. Ammann, A. Rang, C. A. Schalley, P. Buerle, Eur. J. Org. Chem. 2006, 1940; b) M. Ammann, P. Buerle, Org. Biomol. Chem. 2005, 3, 4143. [12] J. J. Pak, T. J. R. Weakley, M. M. Haley, J. Am. Chem. Soc. 1999, 121, 8182. [13] C. O. Dietrich-Buchecker, A. Khemiss, J. P. Sauvage, J. Chem. Soc. Chem. Commun. 1986, 1376. [14] A. S. Hay, J. Org. Chem. 1962, 27, 3320. [15] A. Lei, M. Srivastava, X. Zhang, J. Org. Chem. 2002, 67, 1969. [16] M. Schmittel, A. Ganz, Chem. Commun. 1997, 999. [17] M. Schmittel, V. Kalsani, C. Michel, P. Mal, H. Ammon, F. Jckel, J. P. Rabe, Chem. Eur. J. 2007, 13, 6223. [18] a) J. Kagan, S. K. Arora, J. Org. Chem. 1983, 48, 4317; b) G. Fuhrmann, J. Krçmer, P. Buerle, Synth. Met. 2001, 119, 125. [19] G. Fuhrmann, T. Debaerdemaeker, P. Buerle, Chem. Commun. 2003, 948. [20] F. Zhang, G. Gçtz, E. Mena-Osteritz, M. Weil, B. Sarkar, W. Kaim, P. Buerle, Chem. Sci. 2011, 2, 781. [21] F. Zhang, G. Gçtz, H. D. F. Winkler, C. A. Schalley, P. Buerle, Angew. Chem. Int. Ed. 2009, 48, 6632; Angew. Chem. 2009, 121, 6758. [22] A. Bhaskar, G. Ramakrishna, K. Hagedorn, O. Varnavski, E. Mena-Osteritz, P. Buerle, T. Goodson III, J. Phys. Chem. B 2007, 111, 946. [23] a) M. Bednarz, P. Reineker, E. Mena-Osteritz, P. Buerle, J. Lumin. 2004, 110, 225; b) J. Casado, V. Hernandez, M. C. Ruiz Delgado, J. T. Lopez Navarrete, G. Fuhrmann, P. Buerle, J. Raman Spectrosc. 2004, 35, 592; c) O. Varnavski, P. Buerle, T. Goodson III, Opt. Lett. 2007, 32, 3083. [24] A. J. Bard, L. R. Faulkner, Electrochemical Methods - Fundamentals and Application, J. Wiley, New York, 2001, 2. Ed. Ch. 6.7, p. 247. [25] O. Hammerich in Organic Electrochemistry. Fourth Edition, Revised and Expanded (Ed. H. Lund, O. Hammerich), Marcel Dekker, New York, 2001, Ch. 2, p. 95. [26] J. Krçmer, PhD thesis, University of Ulm (Germany), 2000. [27] a) M. G. Hill, K. R. Mann, L. L. Miller, J.-F. Penneau, J. Am. Chem. Soc. 1982, 104, 2718; b) M. G. Hill, J.-F. Penneau, B. Zinger, K. R. Mann, L. L. Miller, Chem. Mater. 1992, 4, 1106. [28] K. M. Knoblock, C. J. Silvestri, D. M. Collard, J. Am. Chem. Soc. 2006, 128, 13680. [29] F. Wrthner, S. Yao, T. Debaerdemaeker, R. Wortmann, J. Am. Chem. Soc. 2002, 124, 9431. [30] Y. Dienes, S. Durben, T. Krpti, T. Neumann, U. Englert, L. Nyulszi, T. Baumgartner, Chem. Eur. J. 2007, 13, 7487. [31] M. Schmittel, U. Lning, M. Meder, A. Ganz, C. Michel, M. Herderich, Heterocycl. Commun. 1997, 3, 493. [32] C. E. Housecroft, B. A. M. Shaykh, A. L. Rheingold, B. S. Haggerty, Inorg. Chem. 1991, 30, 125. [33] C. O. Dietrich-Buchecker, J. P. Sauvage, J. M. Kern, J. Am. Chem. Soc. 1989, 111, 7791. [34] J. Krçmer, P. Buerle, Tetrahedron 2001, 57, 3785. [35] Melting points could not be determined due to very slow decomposition.

[2]Catenane (7)2 : To a mixture of compound (6 D)2 (40 mg, 18 mmol) and Na2S (0.14 g, 1.8 mmol) was added DMF (18 mL) and 2-methoxyethanol (18 mL). The resultant mixture was heated at 140 8C for 60 h under argon. The reaction solution was extracted with dichloromethane (3 10 mL) and washed with water (5 3 mL). A first purification was accomplished by using a short silica column and SEC (eluent: tetrahydrofuran), followed by column chromatography on silica gel (eluent: 10:13 THF/petroleum ether). Finally, [2]catenane (7)2 (4 mg, 10 %) was isolated as a red solid.[35] 1 H NMR (400 MHz, CD2Cl2): 8.27 (d, 3J = 8 Hz, 4 H, PhenH-4), 8.07 (m, 4 H, ThH-B), 8.00 (d, 3J = 8 Hz, 4 H, PhenH-3), 7.72 (s, 4 H, PhenH-5), 7.18 (s, 4 H, ThH-B’’’), 7.16 (d, 3J = 4 Hz, 4 H, ThH-B’’), 7.12 (d, 3J = 4 Hz, 4 H, ThH-C’’), 7.02 (d, 3J = 4 Hz, 4 H, ThH-C), 2.85–2.83 (m, 24 H, -CH2-), 2.72 (t, 3J = 7 Hz, -CH2-), 1.32–1.16 ppm (m, 48 H, -CH3); 13 C NMR (125 MHz, CD2Cl2): 151.8, 145.9, 145.5, 142.2, 141.5, 140.8, 140.7, 138.0, 137.5, 136.8, 136.4, 135.4, 130.5, 130.4, 130.03, 129.95, 128.6, 128.1, 127.4, 126.0, 125.7, 123.71, 123.68, 119.4, 21.22, 21.2, 21.1, 21.0, 15.1, 15.0, 14.9, 14.8 ppm; HRMS calcd for [M] + : 2280.38599; found: 2280.38305.

Acknowledgements This work was supported by the DFG in the frame of collaborative research center (SFB) 569. X.Z. thanks the Alexander von Humboldt foundation for a postdoctoral fellowship for foreign researchers. Keywords: catenanes · conjugation · systems · macrocycles · synthetic methods

donor–acceptor

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Received: November 10, 2014 Published online on && &&, 0000

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FULL PAPER & Catenanes

A little give and take: A family of [2]catenanes comprising two interlocked p-conjugated donor–acceptor macrocycles based on electron-rich oligothiophene and electron-deficient phenanthroline moieties is synthesized by transition metal-templated macrocyclization followed by Pd-catalyzed cross-coupling. Determination of the optical and redox behavior allows rare insight into the mutual influence of the various components on physical properties.

Chem. Eur. J. 2015, 21, 1 – 19

www.chemeurj.org


G. Gçtz, X. Zhu, A. Mishra, J.-L. Segura, E. Mena-Osteritz, P. Buerle* && – && p-Conjugated [2]Catenanes Based on Oligothiophenes and Phenanthrolines: Efficient Synthesis and Electronic Properties

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