Introduction of Research

Ultralong C-C Bonds with World Record

As exploring the new facet of covalent bond, we have investigated expansion of C-C bond, and finally succeeded in synthesizing the compound with the greatest bond length of 1.806(2) A which was isolated as a stable crystalline material. Research for the world-record compound is interesting since the extreme geometry would provide profound understanding of the basic chemistry.

Advanced Molecular Response Systems Endowed with Multi-input and Multi-output Functions

Organic compounds undergoing reversible photo- or thermal-interconversion between two stable states can be considered as responsive molecules, especially when the two states exhibit different physical/spectral properties. We have investigated electrochromic materials by which color change is induced by applying electric potential. They are the prototype of “unimolecular memory” or would be used in developing “molecular computer” as “molecular operators” by endowing the multi-input and/or multi-output functions.

Stable Open-shell Species Based on Novel Nitrogen-heterocycles

The term “radical” in chemistry means the species with an unpaired election in the molecule, which is very reactive in general. By extending the pi-framework in which the electron can be delocalized, a certain stability is given for the radicals. Stable forms of ion-radical/neutral-radical have been attracting a considerable attention from the material science due to their special properties, and we have designed and synthesized a series of N-heterocyclic pi-extended radicals whose properties can be finely tuned by attaching various substituents.

Multi-chromism: Electrochromism in Solution and Mechanofluorochromism in a Solid State

Electrochromic response is easy to observe in solution whereas mechanochromism induces color or emission change in the solid state. We have developed a series of tetraarylquinodimethanes, which exhibit electrochromism in solution with a drastic structural change between neutral folded form and cationic twisted form. It is interesting to note that the same compound exhibits mechanofluorochromism in the solid state, thus realize the two-way chromism in solution and in the solid state.

Completely Switchable Oxidation Based on Photo- and Thermal Isomerization

The “overcrowded ethene (OCE)” is the name given for the compounds with a bent or twisted C=C double bond due to severe steric repulsion. The bent double bond cause two isomeric forms of (syn- and anti-) which can be interconverted in some cases that are applied to construct “Molecular Machine”. We have studied redox-active OCEs with two dibenzocycloheptatriene moieties, in which redox properties can be controlled by light and heat for the first time based on the syn- and anti-isomerization.

Switching of Redox Properties Triggered by a Thermal Equilibrium

Another change in the studies on “overcrowded ethene (OCE)” is the control of twisted form contribution. In general, twisted form is less stable and could be observed only in the specific molecular framework. We have realized that properly substituted tetraarylquinodimethane has a folded structure but with a bistable twisted form which is accessible by thermal equilibrium. Thus, the room-temperature redox properties exhibit easy oxidation due to the contribution of diradicalic twisted form whereas those phenomenon is completely switched off at low temperature, thus establishing the thermal control of redox properties.

Dynamic Helical Molecules Based on Terephthalamides

As artists express themselves by their drawings or sculptures, chemist can express themselves by designing and creating the molecules. Different shape of molecule corresponds different properties, as exemplified by the chiral molecules with handedness. Chirality is caused by several elements including helicity, and there still is the unrealized form of chiral molecules with a new aspect of helicity. We have realized the unexplored chiral chemistry based on the terephthalamide-based molecules with a characteristic shape of “figure-of-eight”, propeller, etc., which enabled us to find unprecedented phenomena in terms of chirality.

Introduction of laboratory

Structural and physical organic chemistry of non-natural organic compounds with special functions.