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Supramolecular and dynamic covalent reactivity
Published on 10 February 2014. Downloaded on 05/06/2014 22:02:08.
Cite this: Chem. Soc. Rev., 2014, 43, 1798
Jonathan R. Nitschke
DOI: 10.1039/c4cs90006e www.rsc.org/csr
The coinage of the term ‘supramolecular’ by Jean-Marie Lehn brought work that had been carried out by a variety of research teams into a single conceptual framework. Subsequent studies of non-covalent interactions went on to establish the utility of examining supramolecular modes of reactivity to address questions ranging from the design of metal–organic frameworks to the binding of drugs to biomolecules. In recent years some chemists’ minds have turned to the exploration of systems whose subunits are linked by strong bonds formed under conditions of thermodynamic equilibration. These systems combine the ability to make complex structures through
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. E-mail: [email protected]
Jonathan R. Nitschke
parallel bond-forming reactions – as with weakly-bound supramolecular systems – with the robustness associated with structures synthesized under kinetic control. Rowan et al. coined the term ‘Dynamic Covalent Chemistry’ (DCC) to describe this field.1 This themed issue provides a view into the turbulent and conceptually rich phase boundary between DCC and supramolecular chemistry. Its reviews describe systems that incorporate reversible linkages varying in strength from the weakest – those that can only be observed in the gas phase – to medium-strength metal–ligand interactions, through to strong covalent bonds. This glimpse cannot hope to be comprehensive, but rather seeks to sketch how concepts of supramolecular reactivity came to evolve in dynamic covalent directions.
Jonathan Nitschke was born in Syracuse, New York, USA. He received his bachelor’s degree from Williams College in 1995 and his doctorate from the University of California, Berkeley in 2001 under the supervision of T. Don Tilley. He then undertook postdoctoral studies with Jean-Marie Lehn in Strasbourg under the auspices of a US NSF fellowship, and in 2003 he started his independent research career as a Maıˆtre-assistant ( fixed-term independent PI) in the Organic Chemistry Department of the University of Geneva. In 2007 he was appointed University Lecturer at Cambridge, where he now holds the position of Reader (Associate Professor, approximately). His research program investigates the self-assembly of complex, functional structures from simple molecular precursors and metal ions.
1798 | Chem. Soc. Rev., 2014, 43, 1798--1799
Schalley and Cera (DOI: 10.1039/ C3CS60360A) lay the groundwork of our issue by discussing the fundamentals of supramolecular reactions and interactions that occur ‘in the void’: the high-vacuum environment inside of a mass spectrometer. These conditions allow for the suppression of dynamic exchange processes between complexes, such that the intrinsic and intramolecular reactivity of structures of interest may be observed, along with processes involving interactions weaker than those between solvent and solute. The section of the themed issue focussing on the use of metal ions is begun by Custelcean (DOI: 10.1039/C3CS60371G), who reviews the use of cationic coordination cages as anion receptors. The review presents various examples of anionencapsulating coordination cages, followed by a discussion of the kinetics and mechanism of these cages’ anion binding, release, and exchange. Johnson et al. (DOI: 10.1039/ C3CS60349K) then discuss the use of metal ion exchange within metal–organic assemblies, both as a synthetic strategy for otherwise-inaccessible structures, and as a means for transforming one assembly into a different one. Transmetalation is also shown to provide a route to prepare complex inorganic clusters in new ways. Fabbrizzi and Boiocchi (DOI: 10.1039/ C3CS60428D) continue with a discussion of how redox processes may be used to induce copper-containing structures to reversibly reassemble from one distinct
This journal is © The Royal Society of Chemistry 2014
View Article Online
Published on 10 February 2014. Downloaded on 05/06/2014 22:02:08.
Editorial
form into another, as the distinct coordination preferences of CuI and CuII result in the preferential stabilization of different architectures. Clever et al. (DOI: 10.1039/C3CS60473J) discuss the many different structures and functions accessible through the deceptively simple combination of bent, bismonodentate ligands and square-planar PdII or PtII. These building blocks come together to form M2L4 cages that can bind guests, intertwine, and react usefully to various stimuli. Yoshizawa and Klosterman (DOI: 10.1039/C3CS60315F) examine the use of anthracene as a versatile building block to construct functional assemblies through covalent and non-covalent links. Anthracene-containing assemblies can possess useful photophysical, photochemical and molecular-recognition properties, and can be held together in different geometries using many different strategies. Herrmann (DOI: 10.1039/C3CS60336A) starts off the dynamic-covalent section by discussing the inception of dynamic covalent chemistry and how dynamic libraries of receptors may be constructed. He then goes on to discuss the use of these methods to interface with and modulate the complex behaviours of biological systems. Stefankiewicz et al. (DOI: 10.1039/ C3CS60326A) then present an overview of the subtle supramolecular interactions
This journal is © The Royal Society of Chemistry 2014
Chem Soc Rev
influencing the outcomes of equilibrating systems, with particular emphasis on DCC of disulfide exchange reactions. The use of several different supramolecular interactions to direct dynamic covalent bond formation is discussed. Miljanic´ et al. (DOI: 10.1039/C3CS60356C) present a complementary take on kinetically controlled phenomena that occur within dynamic libraries, including dynamic chiral resolution, self-sorting, and autocatalytic behaviour, concluding with a discussion of how the preparation of covalent organic frameworks (COFs) requires a careful balance between the crystal growth and error correction rates within complex libraries. Mastalerz and Zhang (DOI: 10.1039/ C3CS60358J) detail how well-defined organic cage compounds may be prepared using DCC in good yields from simple precursors, and the uses to which these cages may be put in the contexts of sorption, recognition, sensing, separation and stabilization of molecules. Matile et al. (DOI: 10.1039/C3CS60342C) then present a summary of the use of several different kinds of mutually orthogonal dynamic covalent bonds to build functional systems. The incorporation of orthogonal dynamic covalent bonds into functional systems is rarely observed, although the incorporation of more than one kind of dynamic covalent linkage can
allow the generation of systems that can self-sort, self-heal, adapt, exchange, replicate, transcribe, or even walk and carry out molecular logic operations. The review of Aprahamian and Su (DOI: 10.1039/C3CS60385G) provides an overview of the uses of hydrazones in the related areas of molecular switches, metallo-assemblies and sensors. These topics highlight how hydrazones behave in a manner distinct from other imines, and how their interactions with metal ions may be used to build up additional structural complexity and sensing functions. Hecht et al. (DOI: 10.1039/C3CS60383K) finish with a broad-ranging survey of how light may be used to control the functioning of both supramolecular and dynamiccovalent systems. Taken together, these reviews speak to the energetic development and richness of contemporary supramolecular reactivity and its conceptual kindred. I hope that readers may find some inspiration here, too, in defining their own new reactions, reactivities, and offshoots of supramolecular science!
References 1 S. J. Rowan, S. J. Cantrill, G. R. L. Cousins, J. K. M. Sanders and J. F. Stoddart, Dynamic covalent chemistry, Angew. Chem., Int. Ed., 2002, 41(6), 898–952.
Chem. Soc. Rev., 2014, 43, 1798--1799 | 1799
EDITORIAL
View Journal | View Issue
Supramolecular and dynamic covalent reactivity
Published on 10 February 2014. Downloaded on 05/06/2014 22:02:08.
Cite this: Chem. Soc. Rev., 2014, 43, 1798
Jonathan R. Nitschke
DOI: 10.1039/c4cs90006e www.rsc.org/csr
The coinage of the term ‘supramolecular’ by Jean-Marie Lehn brought work that had been carried out by a variety of research teams into a single conceptual framework. Subsequent studies of non-covalent interactions went on to establish the utility of examining supramolecular modes of reactivity to address questions ranging from the design of metal–organic frameworks to the binding of drugs to biomolecules. In recent years some chemists’ minds have turned to the exploration of systems whose subunits are linked by strong bonds formed under conditions of thermodynamic equilibration. These systems combine the ability to make complex structures through
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. E-mail: [email protected]
Jonathan R. Nitschke
parallel bond-forming reactions – as with weakly-bound supramolecular systems – with the robustness associated with structures synthesized under kinetic control. Rowan et al. coined the term ‘Dynamic Covalent Chemistry’ (DCC) to describe this field.1 This themed issue provides a view into the turbulent and conceptually rich phase boundary between DCC and supramolecular chemistry. Its reviews describe systems that incorporate reversible linkages varying in strength from the weakest – those that can only be observed in the gas phase – to medium-strength metal–ligand interactions, through to strong covalent bonds. This glimpse cannot hope to be comprehensive, but rather seeks to sketch how concepts of supramolecular reactivity came to evolve in dynamic covalent directions.
Jonathan Nitschke was born in Syracuse, New York, USA. He received his bachelor’s degree from Williams College in 1995 and his doctorate from the University of California, Berkeley in 2001 under the supervision of T. Don Tilley. He then undertook postdoctoral studies with Jean-Marie Lehn in Strasbourg under the auspices of a US NSF fellowship, and in 2003 he started his independent research career as a Maıˆtre-assistant ( fixed-term independent PI) in the Organic Chemistry Department of the University of Geneva. In 2007 he was appointed University Lecturer at Cambridge, where he now holds the position of Reader (Associate Professor, approximately). His research program investigates the self-assembly of complex, functional structures from simple molecular precursors and metal ions.
1798 | Chem. Soc. Rev., 2014, 43, 1798--1799
Schalley and Cera (DOI: 10.1039/ C3CS60360A) lay the groundwork of our issue by discussing the fundamentals of supramolecular reactions and interactions that occur ‘in the void’: the high-vacuum environment inside of a mass spectrometer. These conditions allow for the suppression of dynamic exchange processes between complexes, such that the intrinsic and intramolecular reactivity of structures of interest may be observed, along with processes involving interactions weaker than those between solvent and solute. The section of the themed issue focussing on the use of metal ions is begun by Custelcean (DOI: 10.1039/C3CS60371G), who reviews the use of cationic coordination cages as anion receptors. The review presents various examples of anionencapsulating coordination cages, followed by a discussion of the kinetics and mechanism of these cages’ anion binding, release, and exchange. Johnson et al. (DOI: 10.1039/ C3CS60349K) then discuss the use of metal ion exchange within metal–organic assemblies, both as a synthetic strategy for otherwise-inaccessible structures, and as a means for transforming one assembly into a different one. Transmetalation is also shown to provide a route to prepare complex inorganic clusters in new ways. Fabbrizzi and Boiocchi (DOI: 10.1039/ C3CS60428D) continue with a discussion of how redox processes may be used to induce copper-containing structures to reversibly reassemble from one distinct
This journal is © The Royal Society of Chemistry 2014
View Article Online
Published on 10 February 2014. Downloaded on 05/06/2014 22:02:08.
Editorial
form into another, as the distinct coordination preferences of CuI and CuII result in the preferential stabilization of different architectures. Clever et al. (DOI: 10.1039/C3CS60473J) discuss the many different structures and functions accessible through the deceptively simple combination of bent, bismonodentate ligands and square-planar PdII or PtII. These building blocks come together to form M2L4 cages that can bind guests, intertwine, and react usefully to various stimuli. Yoshizawa and Klosterman (DOI: 10.1039/C3CS60315F) examine the use of anthracene as a versatile building block to construct functional assemblies through covalent and non-covalent links. Anthracene-containing assemblies can possess useful photophysical, photochemical and molecular-recognition properties, and can be held together in different geometries using many different strategies. Herrmann (DOI: 10.1039/C3CS60336A) starts off the dynamic-covalent section by discussing the inception of dynamic covalent chemistry and how dynamic libraries of receptors may be constructed. He then goes on to discuss the use of these methods to interface with and modulate the complex behaviours of biological systems. Stefankiewicz et al. (DOI: 10.1039/ C3CS60326A) then present an overview of the subtle supramolecular interactions
This journal is © The Royal Society of Chemistry 2014
Chem Soc Rev
influencing the outcomes of equilibrating systems, with particular emphasis on DCC of disulfide exchange reactions. The use of several different supramolecular interactions to direct dynamic covalent bond formation is discussed. Miljanic´ et al. (DOI: 10.1039/C3CS60356C) present a complementary take on kinetically controlled phenomena that occur within dynamic libraries, including dynamic chiral resolution, self-sorting, and autocatalytic behaviour, concluding with a discussion of how the preparation of covalent organic frameworks (COFs) requires a careful balance between the crystal growth and error correction rates within complex libraries. Mastalerz and Zhang (DOI: 10.1039/ C3CS60358J) detail how well-defined organic cage compounds may be prepared using DCC in good yields from simple precursors, and the uses to which these cages may be put in the contexts of sorption, recognition, sensing, separation and stabilization of molecules. Matile et al. (DOI: 10.1039/C3CS60342C) then present a summary of the use of several different kinds of mutually orthogonal dynamic covalent bonds to build functional systems. The incorporation of orthogonal dynamic covalent bonds into functional systems is rarely observed, although the incorporation of more than one kind of dynamic covalent linkage can
allow the generation of systems that can self-sort, self-heal, adapt, exchange, replicate, transcribe, or even walk and carry out molecular logic operations. The review of Aprahamian and Su (DOI: 10.1039/C3CS60385G) provides an overview of the uses of hydrazones in the related areas of molecular switches, metallo-assemblies and sensors. These topics highlight how hydrazones behave in a manner distinct from other imines, and how their interactions with metal ions may be used to build up additional structural complexity and sensing functions. Hecht et al. (DOI: 10.1039/C3CS60383K) finish with a broad-ranging survey of how light may be used to control the functioning of both supramolecular and dynamiccovalent systems. Taken together, these reviews speak to the energetic development and richness of contemporary supramolecular reactivity and its conceptual kindred. I hope that readers may find some inspiration here, too, in defining their own new reactions, reactivities, and offshoots of supramolecular science!
References 1 S. J. Rowan, S. J. Cantrill, G. R. L. Cousins, J. K. M. Sanders and J. F. Stoddart, Dynamic covalent chemistry, Angew. Chem., Int. Ed., 2002, 41(6), 898–952.
Chem. Soc. Rev., 2014, 43, 1798--1799 | 1799
