Mixed‐Valence Nickel Bis(azamacrocycle) Compounds with Ghost‐Leg‐type Sheets

The fabrication of so‐called ghost‐leg sheets and their electronic properties is reported. This unique sheet structure is composed of one‐dimensional mixed‐valence nickel chains, which are linked with one another by bis(azamacrocycle) ligands. They are also topologically unique Ni^II/Ni^III mixed‐valence complexes, as confirmed by X‐ray and optical measurements. Moreover, their magnetic susceptibilities indicated two‐dimensional antiferromagnetic behavior following the Fisher 1D chain model with interchain interactions, where spins on Ni^III sites mutually interact antiferromagnetically in the sheets.     

CO2 Capture from Ambient Air by Crystallization with a Guanidine Sorbent

Carbon capture and storage is an important strategy for stabilizing the increasing concentration of atmospheric CO₂ and the global temperature. A possible approach toward reversing this trend and decreasing the atmospheric CO₂ concentration is to remove the CO₂ directly from air (direct air capture). Herein we report a simple aqueous guanidine sorbent that captures CO₂ from ambient air and binds it as a crystalline carbonate salt by guanidinium hydrogen bonding. The resulting solid has very low aqueous solubility (K _sp=1.0(4)×10⁻⁸), which facilitates its separation from solution by filtration. The bound CO₂ can be released by relatively mild heating of the crystals at 80–120 °C, which regenerates the guanidine sorbent quantitatively. Thus, this crystallization‐based approach to CO₂ separation from air requires minimal energy and chemical input, and offers the prospect for low‐cost direct air capture technologies.     

Transient Helicity: Fuel‐Driven Temporal Control over Conformational Switching in a Supramolecular Polymer

Synthetic manifestations of supramolecular chirality have extensively drawn inspiration from naturally occurring systems. Even though in biological systems conformational changes are dissipative, synthetic systems that change conformation under non‐equilibrium conditions have still not been established. Herein, we attempt to alleviate this scenario by reporting a synthetic supramolecular system that undergoes temporal changes in its helical conformation as an active system at the expense of a biologically relevant chemical fuel, ATP. Use of enzymes working in tandem provides transient and switchable helices with modular lifetime and stereomutation rates.     

Tunable Supramolecular Assembly and Photoswitchable Conversion of Cyclodextrin/Diphenylalanine‐Based 1D and 2D Nanostructures

A photocontrolled, interconvertible supramolecular 2D‐nanosheet/1D‐nanotube system was constructed through the supramolecular assembly of adamantanyl‐modified diphenylalanine with azobenzene‐bridged bis(β‐cyclodextrin). The nanosheet exhibited a greater fluorescence enhancement effect than the nanotube. Significantly, these nanosheets and nanotubes could interconvert via the photocontrolled trans/cis isomerization of azobenzene linkers in bis(β‐cyclodextrin), and this photo‐switchable one‐dimensional/two‐dimensional morphological interconversion was reversible and recyclable. This enables convenient routes to highly ordered nanostructures with various morphologies and dimensions that can be controlled by external stimuli.