Various conventional reactions in polymer chemistry have been translated to the supramolecular domain, yet it has remained challenging to devise living supramolecular polymerization. To achieve this, ...self-organization occurring far from thermodynamic equilibrium--ubiquitously observed in nature--must take place. Prion infection is one example that can be observed in biological systems. Here, we present an 'artificial infection' process in which porphyrin-based monomers assemble into nanoparticles, and are then converted into nanofibres in the presence of an aliquot of the nanofibre, which acts as a 'pathogen'. We have investigated the assembly phenomenon using isodesmic and cooperative models and found that it occurs through a delicate interplay of these two aggregation pathways. Using this understanding of the mechanism taking place, we have designed a living supramolecular polymerization of the porphyrin-based monomers. Despite the fact that the polymerization is non-covalent, the reaction kinetics are analogous to that of conventional chain growth polymerization, and the supramolecular polymers were synthesized with controlled length and narrow polydispersity.
The presence of anomalous chirality in a roll of graphitic carbon sheets has been recognized since the discovery of carbon nanotubes, which are becoming available in higher quantities through the ...isolation of chiral single-wall congeners with high purity. Exploration of the properties arising from cylinder chirality is expected to expand the scope of tubular entities in the future. By studying molecular fragments of helical carbon nanotubes, we herein reveal interesting properties that arise from this chirality. The chirality of nanoscale cylinders resulted in chirality of larger dimensions in the form of a double-helix assembly. Cylinder chirality in solution gave rise to a large dissymmetry factor of metal-free entities in circular polarized luminescence. Theoretical investigations revealed the pivotal role of cylindrical shapes in enhancing magnetic dipole transition moments to yield extreme rotatory strength. Unique effects of cylinder chirality in this study may prompt the development of tubular entities, for instance, toward chiroptical applications.
Spiraling into control: A photoresponsive supramolecular assembly demonstrates that light, along with heating (Δ) and cooling (), can cause chiral communication between molecules. This effect leads ...to bias in the helicity of the complex, causing a reversible switching of macroscopic handedness, as shown by a reversal of sign of the circularly polarized luminescence (CPL) that is emitted.
The highly enantioselective synthesis of helically chiral 1,1'-bitriphenylenes has been achieved via rhodium-catalyzed double 2 + 2 + 2 cycloaddition of biaryl-linked tetraynes with 1,4-diynes (up to ...93% ee). Crystal structures and photophysical properties of these helically chiral 1,1'-bitriphenylenes have also been studied.
High in fiber: 1D fibrous superstructures are formed by an enantiopure phthalhydrazide‐functionalized helicene in nonpolar solvents. Trimeric disks are formed by hydrogen‐bonding interactions of ...phthalhydrazide units that are longitudinally interlocked for optimal packing (see picture). The resulting supramolecular assemblies exhibited large circularly polarized luminescence in solution.
Secondary organic aerosol (SOA) contributes significantly to ambient fine particulate matter that affects climate and human health. Monoterpenes represent an important class of biogenic volatile ...organic compounds (VOCs) and their oxidation by nitrate radicals poses a substantial source of SOA globally. Here, we investigate the formation and properties of SOA from nitrate radical oxidation of two common monoterpenes, α-pinene and limonene. When two monoterpenes are oxidized simultaneously, we observe a ~50% enhancement in the formation of SOA from α-pinene and a ~20% reduction in limonene SOA formation. The change in SOA yields is accompanied by pronounced changes in aerosol chemical composition and volatility. These non-linear effects are not observed in a sequential oxidation experiment. Our results highlight that unlike currently assumed in atmospheric models, the interaction of products formed from individual VOCs should be accounted for to accurately describe SOA formation and its climate and health impacts.
Implementing chemical reactivity into synthetic supramolecular polymers based on π-conjugated molecules has been of great interest to create functional materials with spatiotemporal dynamic ...properties. However, the development of an
chemical reaction within supramolecular polymers is still in its infancy, because one needs to design optimal π-conjugated monomers having excellent reactivity under mild conditions possibly without byproducts or a catalyst. Herein we report the synthesis of a supramolecular polymer based on ethynyl core-substituted naphthalenediimide (S-NDI2) molecules that react with various amines quantitatively in a nonpolar solvent, without a catalyst, at 298 K. Most interestingly, the
reaction of the S-NDI2 supramolecular polymer with a linear aliphatic diamine proceeded much faster than the homogeneous reaction of a monomeric naphthalenediimide with the same diamine, affording diamine-linked S-NDI2 oligomers and polymers. The acceleration of
hydroamination was presumably due to rapid intra-supramolecular cross-linking between ethynyl and amino groups fixed in close proximity within the supramolecular polymer. Such intra-supramolecular cross-linking did not occur efficiently with an incompatible diamine. The systematic kinetic studies of
catalyst-free hydroamination within supramolecular polymers provide us with a useful, facile and versatile tool kit for designing dynamic supramolecular polymeric materials based on electron-deficient π-conjugated monomers.
Abstract
Connecting molecular-level phenomena to larger scales and, ultimately, to sophisticated molecular systems that resemble living systems remains a considerable challenge in supramolecular ...chemistry. To this end, molecular self-assembly at higher hierarchical levels has to be understood and controlled. Here, we report unusual self-assembled structures formed from a simple porphyrin derivative. Unexpectedly, this formed a one-dimensional (1D) supramolecular polymer that coiled to give an Archimedean spiral. Our analysis of the supramolecular polymerization by using mass-balance models suggested that the Archimedean spiral is formed at high concentrations of the monomer, whereas other aggregation types might form at low concentrations. Gratifyingly, we discovered that our porphyrin-based monomer formed supramolecular concentric toroids at low concentrations. Moreover, a mechanistic insight into the self-assembly process permitted a controlled synthesis of these concentric toroids. This study both illustrates the richness of self-assembled structures at higher levels of hierarchy and demonstrates a topological effect in noncovalent synthesis.
Far‐from‐equilibrium thermodynamic systems that are established as a consequence of coupled equilibria are the origin of the complex behavior of biological systems. Therefore, research in ...supramolecular chemistry has recently been shifting emphasis from a thermodynamic standpoint to a kinetic one; however, control over the complex kinetic processes is still in its infancy. Herein, we report our attempt to control the time evolution of supramolecular assembly in a process in which the supramolecular assembly transforms from a J‐aggregate to an H‐aggregate over time. The transformation proceeds through a delicate interplay of these two aggregation pathways. We have succeeded in modulating the energy landscape of the respective aggregates by a rational molecular design. On the basis of this understanding of the energy landscape, programming of the time evolution was achieved through adjusting the balance between the coupled equilibria.
Finding the right balance: The energy landscape of a supramolecular polymerization in which the supramolecular assembly transforms from a J‐aggregate to an H‐aggregate over time has been modulated by a rational molecular design. Based on this, kinetic control over pathway complexity was achieved through adjusting the balance between the coupled equilibria.
Development of facile and versatile synthetic tools for decorating π‐conjugated molecules has attracted considerable interest because of their potential application in creating novel functional ...π‐systems. Reported herein are quantitative catalyst‐free hydroamination reactions of a series of aromatic diimide compounds having vinyl groups at the π‐core, which have been confirmed by NMR, UV‐vis absorption spectroscopy, mass analysis, and single‐crystal X‐ray structural analysis. Kinetic studies revealed that the hydroamination reaction of a vinyl‐substituted naphthalenediimide with an aliphatic amine proceeded rapidly under benign conditions. Similarly, the two vinyl groups attached to aromatic diimides reacted with amines simultaneously, resulting in the formation of amine bisadducts and macromolecules. An amino group appended perylenediimide through an ethylene spacer at the π‐core exhibited distinct fluorescence switching in response to acid and base.
Without a catalyst! Catalyst‐free hydroamination reactions of a series of aromatic diimide compounds having vinyl groups proceeded quantitatively to afford simple but hitherto unexplored amino‐group appended π‐systems. This hydroamination reaction offers a versatile platform to create amino‐functionalized π‐electron materials.
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