Balakrishna Bugga

A detailed investigation of the hierarchy of asymmetry operating in the self-assembly of achiral (1) and chiral ((S)-2 and (R)-3) 1,3,5-triphenylbenzenetricarboxamides (TPBAs) is reported. The aggregation of these TPBAs is conditioned by the point chirality at the peripheral side chains for (S)-2 and (R)-3. An efficient helix-to-helix interaction that goes further in the organization of fibrillar bundles is experimentally detected and theoretically supported only for the achiral TPBA 1. The effective interdigitation of the achiral aliphatic side chains produces a social self-sorting to form preferentially heterochiral macromolecular aggregates.

The self-assembly of 1,3,5-triphenylbenzenetricarboxamides (TPBAs) is reported. The helical outcome is conditioned by the point chirality with an efficient helix-to-helix interaction that goes further in the organization of fibrillar bundles. The effective interdigitation of the achiral aliphatic side chains produces a social self-sorting to form preferentially heterochiral macromolecular aggregates.

Axial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central-to-axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling.

Talking sense: A convergence of the concepts of dynamic covalent chemistry and axial chirality enabled the reversible incorporation and chirality sensing of multiple classes of mononucleophiles (see picture). Selectivity toward different classes of nucleophiles could also be induced by regulating the distinct reactivity of the system with external stimuli.

Boron has one valence electron less than a carbon atom and an available vacant p_z orbital. The incorporation of sp²-hybridized boron atoms into the host lattice of a polycyclic aromatic hydrocarbon (PAH) is formally related to oxidative doping. A boron-containing B-PAH has an energetically low-lying LUMO and a narrow HOMO–LUMO gap, which renders it a strong Lewis acid/electron acceptor and promotes fluorescence in the visible range of the electromagnetic spectrum. Many methods have been developed to access B-PAHs that are deliberately designed for specific tasks. Herein, we highlight recent breakthroughs in the field of B-PAH synthesis and the scope of their applications, which range from Lewis acid and redox catalysis to device fabrication. We will also report on the dynamic covalent chemistry of neutral and anionic B-PAHs, as it is a potential limitation in the design of catalyst systems but can also provide a powerful synthetic tool for the preparation of otherwise inaccessible B-PAHs.

Delightful deficiency: Because of its vacant p orbital, an incorporated boron atom can imprint peculiar optoelectronic properties on polycyclic aromatic hydrocarbons (PAHs). Recently, synthetic strategies have been developed to provide access to B-PAHs that are specifically tailored to applications as catalysts for the activation of small molecules or as luminophores and charge carriers in optoelectronic devices.