DOI: 10.1002/chem.201403132

Communication

& Mechanochromic Luminescence

Mechanochromic Behavior of Aryl-Substituted Buta-1,3-Diene Derivatives with Aggregation Enhanced Emission Yijia Zhang,[a] Ting Han,[a] Shangzhi Gu,[a] Tianye Zhou,[a] Chuanzhen Zhao,[a] Yuexin Guo,[b] Xiao Feng,*[b] Bin Tong,[a] J. Bing,[a] Jianbing Shi,[a] Junge Zhi,[b] and Yuping Dong*[a] posed and investigated. For example, Araki et al. described the switching of fluorescence in a hexyl amide-substituted tetraphenylpyrene derivative relative to intermolecular hydrogenbond interactions;[5] Ito et al. demonstrated the mechanochromic behavior of a gold complex undergoing a meta-stable to stable phase change;[6] Fraser et al. reported morphology-dependent fluorescence for solid states of difluoroboron avobenzone.[7] Nevertheless, most studies have focused on regulating molecular packing modes and consequent intermolecular interactions;[8] examination of the effect of molecular structure on the mechanochromic behavior is rather limited.[9] In this respect, it is essential to establish a correlation between molecular structure and mechanochromic solid-state photophysical properties. Mechanochromic luminogens with efficient solid-state emission and large contrast are particularly desirable for practical applications. The development of aggregation induced/enhanced emission (AIE/AEE) materials,[10] showing no emission or little emission in dilute solutions but becoming brightly fluorescent in nanoparticles or films, paves the way for designing highly emissive solid-state fluorophores. The restriction of intramolecular rotations (RIR) in aggregated states, which blocks the non-radiative pathway and opens up the radiative channel, is proposed to account for the exceptional AIE/AEE phenomenon.[11] Limited examples of AIE-active mechanochromic luminogens have been reported.[12] We have recently described a tetraphenylbutadiene (TABD) derivative with two carboxyl groups as substituents, the photoluminescent color of which can be altered by gentle grinding and recovered upon exposure to solvents.[13] We also clarified the role of the hydrogen bonds in the mechanochromic response. In this report, three compounds derived from the TABD molecule, namely dimethyl 4,4’-((1Z,3Z)-1,4-diphenylbuta-1,3-diene-1,4-diyl)dibenzoate (TABDE), dimethyl 4,4’-((1Z,3Z)1,4-bis(4-(trifluoromethyl)phenyl)buta-1,3-diene-1,4-diyl)dibenzoate (TABDE-CF3), and dimethyl 4,4’-((1Z,3Z)-1,4-bis(4-(diphenylamino)phenyl)buta-1,3-diene-1,4-diyl)dibenzoate (TABDENPh2), are employed for the systematic and comparative study of the structural effect on mechanochromic performance. In these three compounds, CF3 and COOCH3 groups act as electron acceptors (A), whereas the NPh2 and TABD moieties serve as electron donors (D) and conjugation bridges, respectively. All of these TABD derivatives are found to possess AEE features as well as mechanochromic properties. The results show that the mechanochromic performance follows the sequence of TABDE-NPh2 > TABDE > TABDE-CF3. This order can be

Abstract: Three tetra-aryl substituted 1,3-butadiene derivatives with aggregation enhanced emission (AEE) and mechanochromic fluorescence behavior have been rationally designed and synthesized. The results suggest an effective design strategy for developing diverse materials with aggregation induced emission (AIE) and significant mechanochromic performance by employing D-p-A structures with large dipole moments.

Mechanochromic luminogens, a class of responsive materials the emission colors of which can be altered in response to external mechanical stimuli such as shearing, grinding, or elongation,[1] have received tremendous attention owing to their potential applications in stress sensors, indicators, luminescence switches, security inks, optical data storage systems and lightemitting devices.[2] A series of mechanochromic luminogens based on organic molecules, organometallic compounds, and dye-doped polymers have been recently developed.[3] It is crucial to understand the underlying mechanisms of mechanochromism from a molecular level and to establish a general method to change and control solid-state luminescence. Dynamic control of solid-state photoluminescent properties by mechanical forces can be achieved by either chemical or physical structural change. Mechanical force induced chemical structural change,[4] involving chemical bond breaking or forming, is highly designable yet suffers from insufficient conversion or irreversible reactions. By contrast, physical structural change is more efficient for attaining mechanochromic behaviors owing to the ease of adjusting molecular stacking modes in the solid state. Up to now, several mechanisms of the mechanochromic process that relies on physical structural change have been pro-

[a] Y. Zhang,+ T. Han,+ S. Gu, T. Zhou, C. Zhao, Prof. B. Tong, Dr. J. Bing, J. Shi, Prof. Y. Dong School of Materials Science & Engineering, Beijing Institute of Technology 5 South Zhongguancun Street, Beijing, 100081 (P.R. China) E-mail: [email protected] [b] Y. Guo, Dr. X. Feng, Prof. J. Zhi School of Chemistry, Beijing Institute of Technology 5 South Zhongguancun Street, Beijing, 100081 (P.R. China) E-mail: [email protected] [+] Y. Zhang and T. Han contributed equally to this work. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201403132. Chem. Eur. J. 2014, 20, 1 – 7

These are not the final page numbers! ÞÞ

1

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

&

&

Communication solution of TABDE-NPh2 triggers not only a clear increase of intensity, but also a significant shift of fluorescent wavelength. This suggests that TABDE-NPh2 favors intramolecular charge transfer (ICT) in the higher polarity solvent mixture. The fluorescence quantum yields (FF) of TABDE-CF3, TABDE, and TABDENPh2 increase by 6.4, 2.4, and 8.5 fold, respectively, when going from their THF solution to the solid state (Table S1 in the Supporting Information). Clearly, all of these three compounds are typical AEE luminogens. The formation of aggregates upon addition of water to their THF solutions is supported by dynamic light scattering (DLS) analysis (Figure S2 in the Supporting Information) and scanning electron microscopy (SEM; Figure S3in the Supporting Information). The results of the Scheme 1. Synthesis routes to the three TABD derivatives. a) 2-methylbut-3-yn-2-ol, Pd(PPh3)2Cl2, CuI, NEt3, 50 8C; b) NaOH, CaH2, toluene, reflux; c) CuBr2, PdCl2, toluene, CH3CN, r.t.; d–f) Pd(PPh3)4, K2CO3, CH3OH, toluene, reflux. size distribution by intensity analysis indicate that the amount of larger nanoparticles in the THF/water mixtures is significantly increased when the attributed to the distinctions in the molecular polarity of these fw is higher than 50 %. Because of the space constraint in these three compounds, as indicated by exploration of their solvatochromic properties and through theoretical calculations. aggregates, the rotations and motions of the multiple aromatic The synthetic routes to these three luminogens are shown rings and C=C bonds in the TABDE derivatives are restricted. in Scheme 1. Intermediate 3 was prepared according to the litTherefore, the nonradiative channels are blocked and the emiserature,[14] and was subsequently dimerized to produce 4 with sions are enhanced. To reveal the mechanism of the AEE processes for TABDE dehigh stereoselectivity by using PdCl2 and CuBr2 as catalysts in rivatives, their molecular geometries and packing arrangeMeCN/Toluene (v/v, 1:50). Finally, TABDE, TABDE-CF3, and ments in the solid state were studied. Single crystals of TABDE TABDE-NPh2 were obtained through Suzuki coupling reaction and TABDE-CF3 were obtained by the diffusion process and of 4 with corresponding boronic acid compounds by using characterized by single-crystal X-ray crystallography (SXRD). Pd(PPh3)4 as a catalyst. Detailed synthetic procedures and charUnfortunately, we were not able to obtain single crystals of acterization data of the compounds from IR, 1H NMR, 13C NMR, and MS spectroscopic studies are available in the Supporting good quality for TABDE-NPh2 owing to the existence of bulky NPh2 groups in the twisted backbone, which is unfavorable Information. The decomposition temperatures (Td) of these three compounds, determined by thermal gravimetric analysis for the highly ordered alignment of molecules. As shown in (TGA), range from 300 to 400 8C (Figure S1 in the Supporting Figure 2, the molecules have twisted conformations maintainInformation), demonstrating that all compounds are thermally ing large torsion angles (688 for TABDE and 608 for TABDE-CF3) stable, which is a required property for further device applicain the crystal. The adjacent molecules in a single molecular tions. column are packed by C H···p hydrogen-bond interactions reFigure 1 shows the fluorescent (FL) spectra of TABDE, sulting in a distance of less than 2.8 , rather than p–p interacTABDE-NPh2, and TABDE-CF3 in THF/water mixtures. For these tions for both derivatives. This distance results in the RIR process and minimizes the likelihood of the formation of excimers three TABD derivatives, the fluorescence intensities of their solin the crystal. These results demonstrate that the formation of utions are negligibly small when the water fraction (fw) is lower aggregates imposes physical restraints on the intramolecular than 70 %. However, in solvent mixtures with fw  70 %, their rotations, and thus populates the radiative excitons. emissions are drastically intensified. A slight redshift of emisBesides AEE properties, we also observed that the powders sion maximum are observed in the FL spectra of TABDE and of TABD derivatives exhibit mechanochromic behavior. The TABDE-CF3, a shift that is attributed to the change in the polarfluorescence of the pristine TABDE-NPh2 powders can change ity of the solvent mixture. The addition of water into the THF &

&

Chem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

2

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ÝÝ These are not the final page numbers!

Communication ducible and can be repeated for many cycles almost without any deterioration (Figure 4), indicating the excellent reversibility of their mechanochromism. To gain insight into the mechanochromic behavior of the solid-state TABDE-NPh2, TABDE, and TABDE-CF3, powder X-ray diffraction (PXRD) experiments of the fumed, ground, and heated samples were conducted (Figure S4 in the Supporting Information). The diffraction patterns of the fumed and heated solids show sharp and intense reflection peaks, indicative of a well-ordered structure. In contrast, the PXRD intensity of the ground samples displays relatively broad and featureless reflection along with a series of weakened peaks, indicating partial deformation of an ordered molecular packing structure. These results confirm that the mechanochromic nature of TABDE-NPh2, TABDE, and TABDECF3 is caused by the disruption of the molecular packing. That is, in the fumed and heated solids, molecules are well organFigure 1. a–c) FL spectra of TABDE, TABDE-CF3, and TABDE-NPh2 in THF/water mixtures with different fw. Concenized, a fact that is reliant on intration: 10 mm; excitation wavelength: 350, 360, and 320 nm, respectively. d) Plots of maximum intensity of termolecular interactions. ApplyTABDE, TABDE-CF3, and TABDE-NPh2 versus fw in THF/water mixtures. ing high pressure can destroy these interactions and leads to the formation of a less ordered phase, where close packing from green to yellow under irradiation with UV light by grindgoverns the molecular arrangement. The permeation of polar ing with a mortar or spatula (Figure 3), and this change could solvents into the powder or heating the samples promotes the be found only at the pressed area. Similar to TABDE-NPh2, regeneration of intermolecular interactions, and thus recovers TABDE and TABDE-CF3 likewise exhibit a pressure-induced lumithe original emissions. nescence change. However, the variation of the emission TABDE-NPh2 exhibits more evident fluorescence alterations change of TABDE and TABDE-CF3 is not as significant as TABDENPh2 (Figure 3). Upon grinding, the fluorescent colors gradually than the other two samples in the fuming–grinding cycles. We consider that the electronic structures of these samples have redshifted from sky blue to cyan for the TABDE solid-state great influence on their mechanochromic behavior. Therefore, powders, and from dark blue to cyan for the TABDE-CF3. The we checked the solvatochromic behavior and calculated the maximum emission wavelength for the pristine and ground frontier molecular orbitals of these three TABD derivatives. samples of TABDE-CF3, TABDE, and TABDE-NPh2, are shifted The electron-accepting CF3 and COOCH3 groups or elecfrom 459, 455, and 520 nm to 465, 465, and 540 nm, respectively (Figure 4). The FF of the pristine and ground powder of tron-donating NPh2 groups endow different kinds of push– TABDE-CF3, TABDE, and TABDE-NPh2 are listed in Table S1 in pull molecular structures on the TABD derivatives. Especially for TABDE-NPh2 with a D-p-A structure, it is envisioned as the Supporting Information. Usefully, the emission colors of the ground samples can be restored to almost their original being capable of forming ICT interactions. To characterize the colors by adding a drop of polar solvent (e.g., MeOH, EtOH, environmental sensitivity of these three compounds, the maxiTHF) or heating at 180 8C for 2 h. These remarkable changes in mal wavelengths for absorbance and emission were measured fluorescence upon grinding are characteristic mechanochromic in solvents with varying polarity. For TABDE-NPh2, the UV abphenomena. Moreover, it is confirmed that the mechanochrosorption spectra changed only a little, but the FL spectra mic behavior of these three TABD-based molecules are reprochanged significantly with increasing solvent polarity parameChem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

These are not the final page numbers! ÞÞ

3

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

&

&

Communication effect. It suggests that the excited state of TABDE-NPh2 has a larger dipole moment than the ground state owing to substantial charge redistribution through the strong polarity. The lines of best fit for TABDE and TABDE-CF3 are negative with small slopes, 724 and 1023 (Figure S6 in the Supporting Information), showing a slight negative solvatochromism effect. The results indicate that among these three compounds, TABDENPh2 is more favorable for the ICT process, and consequently verifying that it possesses the highest molecular polarity. To better understand the electronic structure effect on the mechanochromic behavior of Figure 2. Molecular packing arrangements in single crystals of a) TABDE and b) TABDE-CF3. the three TABD derivatives, density functional theory (DFT) calculations (B3LYP/6-31G) were ter (Df). An evident redshift with Df from light green (lem = carried out. The highest occupied molecular orbital (HOMO) 509 nm) to pink (lem = 585 nm) was observed when the solvent and lowest unoccupied molecular orbital (LUMO) plots are changed from a nonpolar one (e.g., hexane) to highly polar shown in Figure S7 in the Supporting Information. Unlike the ones (e.g., DMF). In contrast, the emissions of TABDE and TABDE-CF3 display only a small bathochromic shift. The influence of Df on the Stokes shift (Dv) was further explored by the Lippert–Mataga equation in the Supporting Information. From the plots of Du versus Df, we can find that the Stokes shift of TABDE-NPh2 with the increase from 1.30  10 2 cm 1 in hexane to 1.53  10 2 cm 1 in DMF gives a large positive slope of 6442, exhibiting significant solvatochromism

Figure 4. a) Maximum emission wavelength change upon repeated fuming– grinding cycles. Squares: after grinding; triangles: after fuming. b) Maximum emission wavelength change upon repeated heating–grinding cycles. Squares: after grinding; triangles: after heating.

Figure 3. Images of the TABD derivatives upon grinding and fuming taken at room temperature under ambient light and 365 nm UV light.

&

&

Chem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

4

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ÝÝ These are not the final page numbers!

Communication minor variations in the electron density distributions of the HOMO and LUMO of TABDE-CF3, the electron clouds of TABDE partially move to the methyl benzoate moieties from HOMO to LUMO. For TABDE-NPh2, the HOMO is primarily localized over the NPh2 moieties, whereas the LUMO is concentrated on the methyl benzoate moieties. These results are consistent with the substituent effects. Therefore, it is supposed that the difference in the mechanochromic behavior of these three compounds is due to the diverse extents of the push–pull interactions involved in the three systems. The substitution of electron-donating and/or electron-accepting groups increases the molecular polarity, leading to the significant impact of intermolecular interactions in the crystalline and less-ordered states of these three materials. The existence of a large dipole moment is favorable to the occurrence of remarkable mechanochromism. To further confirm our hypothesis, TABD without any substituents was synthesized. The results show that TABD is also a typical AEE luminogen and its maximum emission wavelength for the pristine and ground samples with high symmetry are only shifted from 427 to 428 nm (Figure S10 in the Supporting Information). The fluorescence of the pristine TABD powder remains dark blue under irradiation with UV light and with grinding with a mortar (Figure S8 in the Supporting Information). That is, TABD exhibits negligible mechanochromic behavior. In summary, we designed and successfully synthesized three comparative TABD derivatives (TABDE, TABDE-NPh2, TABDECF3), with both AEE and reversible mechano-responsive properties, and systematically investigated the effects of D and/or A substitutions on their mechanochromic properties. Owing to the introduction of both electron-accepting and -donating moieties in TABDE-NPh2, it exhibits the most remarkable mechanochromic behavior of the three compounds. The results imply that it is an effective molecular strategy to design mechanochromic materials with large contrast and high fluorescence quantum yield by utilizing AIE luminogens with large dipole moments. It may also shed light on the development of a new class of mechanochromic materials, and provide molecular insights into tuning the fluorescence of solid-state materials.

[2]

[3]

[4]

[5] [6]

[7] [8]

Acknowledgements The work reported in this paper was partially supported by the National Basic Research Program of China (973 Program; 2013CB834704), the National Science Foundation of China (51073026, 51061160500, 21074011, and 51328302) and the Basic Research Foundation of the Beijing Institute of Technology (20131942002).

[9] [10]

Keywords: 1,3-butadiene · aggregation enhanced emission · chromophores · fluorescence · mechanochromic luminescence

[11]

[1] a) Z. G. Chi, X. Q. Zhang, B. J. Xu, X. Zhou, C. P. Ma, Y. Zhang, S. W. Liu, J. R. Xu, Chem. Soc. Rev. 2012, 41, 3878 – 3896; b) Y. Sagara, T. Kato, Nat. Chem. 2009, 1, 605 – 610; c) K. Ariga, T. Mori, J. P. Hill, Adv. Mater. 2012, Chem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

These are not the final page numbers! ÞÞ

5

24, 158 – 176; d) X. Zhang, Z. Chi, Y. Zhang, S. Liu, J. Xu, J. Mater. Chem. C 2013, 1, 3376 – 3390. a) B. R. Crenshaw, M. Burnworth, D. Khariwala, A. Hiltner, P. T. Mather, R. Simha, C. Weder, Macromolecules 2007, 40, 2400 – 2408; b) J. R. Lawrence, G. H. Shim, P. Jiang, M. G. Han, Y. R. Ying, S. H. Foulger, Adv. Mater. 2005, 17, 2344 – 2349; c) N. Mizoshita, T. Tani, S. Inagaki, Adv. Mater. 2012, 24, 3350 – 3355; d) J. Luo, L. Y. Li, Y. L. Song, J. Pei, Chem. Eur. J. 2011, 17, 10515 – 10519; e) Y. Zhang, G. Gao, H. L. W. Chan, J. Dai, Y. Wang, J. Hao, Adv. Mater. 2012, 24, 1729 – 1735; f) G. G. Shan, H. B. Li, D. X. Zhu, Z. M. Su, Y. Liao, J. Mater. Chem. 2012, 22, 12736 – 12744; g) D. P. Yan, J. Lu, J. Ma, S. H. Qin, M. Wei, D. G. Evans, X. Duan, Angew. Chem. 2011, 123, 7175 – 7178; Angew. Chem. Int. Ed. 2011, 50, 7037 – 7040; h) Y. L. Wang, W. Liu, L. Y. Bu, J. F. Li, M. Zheng, D. T. Zhang, M. X. Sun, Y. Tao, S. F. Xue, W. J. Yang, J. Mater. Chem. C 2013, 1, 856 – 862. a) P. Zhang, W. Dou, Z. Ju, X. Tang, W. Liu, C. Chen, B. Wang, W. Liu, Adv. Mater. 2013, 25, 6112 – 6116; b) Z. Y. Ma, M. J. Teng, Z. J. Wang, S. Yang, X. R. Jia, Angew. Chem. 2013, 125, 12494 – 12498; Angew. Chem. Int. Ed. 2013, 52, 12268 – 12272; c) Y. Sagara, T. Komatsu, T. Ueno, K. Hanaoka, T. Kato, T. Nagano, Adv. Funct. Mater. 2013, 23, 5277 – 5284; d) M. S. Kwon, J. Gierschner, S.-J. Yoon, S. Y. Park, Adv. Mater. 2012, 24, 5487 – 5492; e) M. J. Teng, X. R. Jia, S. Yang, X. F. Chen, Y. Wei, Adv. Mater. 2012, 24, 1255 – 1261; f) E. P. Chan, J. J. Walish, E. L. Thomas, C. M. Stafford, Adv. Mater. 2011, 23, 4702 – 4706; g) J. Kunzelman, M. Kinami, B. R. Crenshaw, J. D. Protasiewicz, C. Weder, Adv. Mater. 2008, 20, 119 – 122; h) C. H. Woodall, C. M. Beavers, J. Christensen, L. E. Hatcher, M. Intissar, A. Parlett, S. J. Teat, C. Reber, P. R. Raithby, Angew. Chem. 2013, 125, 9873 – 9876; Angew. Chem. Int. Ed. 2013, 52, 9691 – 9694; i) Y. Ren, W. H. Kan, V. Thangadurai, T. Baumgartner, Angew. Chem. 2012, 124, 4031 – 4035; Angew. Chem. Int. Ed. 2012, 51, 3964 – 3968; j) S. Perruchas, X. F. Le Goff, S. Maron, I. Maurin, F. Guillen, A. Garcia, T. Gacoin, J. P. Boilot, J. Am. Chem. Soc. 2010, 132, 10967 – 10969. a) D. A. Davis, A. Hamilton, J. L. Yang, L. D. Cremar, D. Van Gough, S. L. Potisek, M. T. Ong, P. V. Braun, T. J. Martinez, S. R. White, J. S. Moore, N. R. Sottos, Nature 2009, 459, 68 – 72; b) M. J. Teng, X. R. Jia, X. F. Chen, Y. Wei, Angew. Chem. 2012, 124, 6504 – 6507; Angew. Chem. Int. Ed. 2012, 51, 6398 – 6401; c) J. W. Chung, Y. You, H. S. Huh, B. K. An, S. J. Yoon, S. H. Kim, S. W. Lee, S. Y. Park, J. Am. Chem. Soc. 2009, 131, 8163 – 8172. Y. Sagara, T. Mutai, I. Yoshikawa, K. Araki, J. Am. Chem. Soc. 2007, 129, 1520 – 1521. H. Ito, T. Saito, N. Oshima, N. Kitamura, S. Ishizaka, Y. Hinatsu, M. Wakeshima, M. Kato, K. Tsuge, M. Sawamura, J. Am. Chem. Soc. 2008, 130, 10044 – 10045. G. Q. Zhang, J. W. Lu, M. Sabat, C. L. Fraser, J. Am. Chem. Soc. 2010, 132, 2160 – 2162. a) G. R. Krishna, M. S. R. N. Kiran, C. L. Fraser, U. Ramamurty, C. M. Reddy, Adv. Funct. Mater. 2013, 23, 1422 – 1430; b) X. Luo, J. Li, C. Li, L. Heng, Y. Q. Dong, Z. Liu, Z. Bo, B. Z. Tang, Adv. Mater. 2011, 23, 3261 – 3265; c) Y. J. Dong, B. Xu, J. B. Zhang, X. Tan, L. J. Wang, J. L. Chen, H. G. Lv, S. P. Wen, B. Li, L. Ye, B. Zou, W. J. Tian, Angew. Chem. 2012, 124, 10940 – 10943; Angew. Chem. Int. Ed. 2012, 51, 10782 – 10785; d) Y. Sagara, T. Kato, Angew. Chem. 2011, 123, 9294 – 9298; Angew. Chem. Int. Ed. 2011, 50, 9128 – 9132; e) K. Nagura, S. Saito, H. Yusa, H. Yamawaki, H. Fujihisa, H. Sato, Y. Shimoikeda, S. Yamaguchi, J. Am. Chem. Soc. 2013, 135, 10322 – 10325; f) S. J. Yoon, J. W. Chung, J. Gierschner, K. S. Kim, M. G. Choi, D. Kim, S. Y. Park, J. Am. Chem. Soc. 2010, 132, 13675 – 13683. F. K. Chen, J. Zhang, X. H. Wan, Chem. Eur. J. 2012, 18, 4558 – 4567. a) J. D. Luo, Z. L. Xie, J. W. Y. Lam, L. Cheng, H. Y. Chen, C. F. Qiu, H. S. Kwok, X. W. Zhan, Y. Q. Liu, D. B. Zhu, B. Z. Tang, Chem. Commun. 2001, 1740 – 1741; b) Y. N. Hong, J. W. Y. Lam, B. Z. Tang, Chem. Soc. Rev. 2011, 40, 5361 – 5388; c) D. Ding, K. Li, B. Liu, B. Z. Tang, Acc. Chem. Res. 2013, 46, 2441 – 2453; d) Y. Z. Zhao, M. M. Cai, Y. Qian, L. H. Xie, W. Huang, Prog. Chem. 2013, 25, 296 – 321; e) J. H. Ma, S. McLeod, K. MacCormack, S. Sriram, N. Gao, A. L. Breeze, J. Hu, Angew. Chem. 2014, 126, 2162 – 2165; Angew. Chem. Int. Ed. 2014, 53, 2130 – 2133. a) A. J. Qin, C. K. W. Jim, Y. H. Tang, J. W. Y. Lam, J. Z. Liu, F. Mahtab, P. Gao, B. Z. Tang, J. Phys. Chem. B 2008, 112, 9281 – 9288; b) Y. N. Hong, J. W. Y. Lam, B. Z. Tang, Chem. Commun. 2009, 4332 – 4353; c) J. Mei, J. Wang, J. Z. Sun, H. Zhao, W. Z. Yuan, C. M. Deng, S. M. Chen, H. H. Y. Sung, P. Lu, A. J. Qin, H. S. Kwok, Y. G. Ma, I. D. Williams, B. Z. Tang, Chem. Sci. 2012, 3, 549 – 558; d) K. Li, W. Qin, D. Ding, N. Tomczak, J. L.  2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

&

&

Communication Geng, R. R. Liu, J. Z. Liu, X. H. Zhang, H. W. Liu, B. Liu, B. Z. Tang, Sci. Rep. 2013, 3, 1150 – 1159; e) N. W. Tseng, J. Z. Liu, J. C. Y. Ng, J. W. Y. Lam, H. H. Y. Sung, I. D. Williams, B. Z. Tang, Chem. Sci. 2012, 3, 493 – 497; f) G. Y. Qing, X. X. Shan, W. R. Chen, Z. Y. Lv, P. Xiong, T. L. Sun, Angew. Chem. 2014, 126, 2156 – 2161; Angew. Chem. Int. Ed. 2014, 53, 2124 – 2129; g) C. C. Nawrat, C. J. Moody, Angew. Chem. 2014, 126, 2086 – 2109; Angew. Chem. Int. Ed. 2014, 53, 2056 – 2077; h) Z. B. Shu, W. Z. Ji, X. Wang, Y. J. Zhou, Y. Zhang, J. B. Wang, Angew. Chem. 2014, 126, 2218 – 2221; Angew. Chem. Int. Ed. 2014, 53, 2186 – 2189; i) Q. K. Qi, J. B. Zhang, B. Xu, B. Li, S. X. A. Zhang, W. J. Tian, J. Phys. Chem. C 2013, 117, 24997 – 25003. [12] a) J. Wang, J. Mei, R. R. Hu, J. Z. Sun, A. J. Qin, B. Z. Tang, J. Am. Chem. Soc. 2012, 134, 9956 – 9966; b) B. Y. Peng, S. D. Xu, Z. G. Chi, X. Q. Zhang, Y. Zhang, J. R. Xu, Prog. Chem. 2013, 25, 1805 – 1820; c) W. Z. Yuan, Y. Q. Tan, Y. Y. Gong, P. Lu, J. W. Y. Lam, X. Y. Shen, C. F. Feng,

&

&

Chem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

H. H. Y. Sung, Y. W. Lu, I. D. Williams, J. Z. Sun, Y. M. Zhang, B. Z. Tang, Adv. Mater. 2013, 25, 2837 – 2843; d) T. Y. Han, Y. N. Hong, N. Xie, S. J. Chen, N. Zhao, E. G. Zhao, J. W. Y. Lam, H. H. Y. Sung, Y. P. Dong, B. Tong, B. Z. Tang, J. Mater. Chem. C 2013, 1, 7314 – 7320; e) J. Q. Shi, W. J. Zhao, C. H. Li, Z. P. Liu, Z. S. Bo, Y. P. Dong, Y. Q. Dong, B. Z. Tang, Chin. Sci. Bull. 2013, 58, 2723 – 2727; f) C. Y. Li, X. L. Luo, W. J. Zhao, Z. Huang, Z. P. Liu, B. Tong, Y. Q. Dong, Sci. China Chem. 2013, 56, 1173 – 1177. [13] T. Han, Y. J. Zhang, X. Feng, Z. G. Lin, B. Tong, J. B. Shi, J. G. Zhi, Y. P. Dong, Chem. Commun. 2013, 49, 7049 – 7051. [14] S. J. Havens, P. M. Hergenrother, J. Org. Chem. 1985, 50, 1763 – 1765.

Received: April 16, 2014 Published online on && &&, 0000

6

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ÝÝ These are not the final page numbers!

Communication

COMMUNICATION & Mechanochromic Luminescence

Mechanochromic luminescence: Three tetra-aryl substituted 1,3-butadiene derivatives with distinct electronic push and/or pull substituents have been prepared. All three derivatives show typical aggregation enhanced emission (AEE) features owing to the restriction of intramolecular rotations. The results demonstrate that chromophores with both large dipole moments and AEE characteristics are of benefit for mechanochromic applications with efficient solidstate emissions.

Chem. Eur. J. 2014, 20, 1 – 7

www.chemeurj.org

These are not the final page numbers! ÞÞ

Y. Zhang, T. Han, S. Gu, T. Zhou, C. Zhao, Y. Guo, X. Feng,* B. Tong, J. Bing, J. Shi, J. Zhi, Y. Dong* && – && Mechanochromic Behavior of ArylSubstituted Buta-1,3-Diene Derivatives with Aggregation Enhanced Emission

7

 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

&

&

Mechanochromic behavior of aryl-substituted buta-1,3-diene derivatives with aggregation enhanced emission.

Three tetra-aryl substituted 1,3-butadiene derivatives with aggregation enhanced emission (AEE) and mechanochromic fluorescence behavior have been rat...
1MB Sizes 1 Downloads 3 Views