Dynamics of proton, ion, molecule, and crystal lattice in functional molecular assemblies

Dynamic molecular processes, such as short- or long-range proton (H⁺) and ion (M⁺) motions, and molecular rotations in electrical conducting and magnetic molecular assemblies enable the fabrication of electron-H⁺ (or M⁺) coupling systems, while crystal lattice dynamics and molecular conformation changes in hydrogen-bonded molecular crystals have been utilised in external stimuli responsive reversible gas-induced gate opening and molecular adsorption/desorption behavior. These dynamics of the polar structural units are responsible for the dielectric measurements. The H⁺ dynamics are formed from ferroelectrics and H⁺ conductors, while the dynamic M⁺ motions of Li⁺ and Na⁺ involve ionic conductors and coupling to the conduction electrons. In n-type organic semiconductors, the crystal lattices are modulated by replacing M⁺ cations, with cations such as Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺. The use of polar rotator or inversion structures such as alkyl amides, m-fluoroanilinium cations, and bowl-shaped trithiasumanene π-cores enables the formation of ferroelectric molecular assemblies. The host-guest molecular systems of ESIPT fluorescent chromic molecules showed interesting molecular sensing properties using various bases, where the dynamic transformation of the crystal lattice and the molecular conformational change were coupled to each other.

Color-tunable arylaminoanthraquinone dyes through hydrogen-bond-assisted charge transfer interaction

We prepared a series of arylaminoanthraquinone derivatives, including those with electron-accepting sulfone units and/or with electron-donating dialkylamino units. A color-tunable anthraquinone library that reached into the NIR region could be prepared through the precise control of frontier orbitals. Fine color-tuning was achieved through proper selection and positioning of the substituents. Effective intramolecular hydrogen-bond-assisted charge transfer interaction between electron-donating aniline/p-phenylenediamine and electron-accepting anthraquinone substructures induced a significant bathochromic shift of anthraquinone. The number and position of the substituents and the molecular conformation also significantly contributed to determining photophysical properties.

A color-tunable anthraquinone library based on arylaminoanthraquinone was prepared through hydrogen-bond-assisted charge transfer interaction.

Conformation change significantly affected the optical and electronic properties of arylsulfonamide-substituted anthraquinones

Simple N-methylation induced dynamic structural change of arylsulfonamide-substituted anthraquinone, which induced drastic change in optical and electronic properties.

Positively and negatively charged NHN hydrogen bonds in one molecule: synergistic strengthening effect, superbasicity and acetonitrile capture

The first full nitrogen zwitterions were synthesized. Both [NHN]⁻ and [NHN]⁺ bridges strongly influence each other, resulting in superbasicity and receptor properties.