■ Introduction to Research〓 Research Area : Advanced Organic Materials

Physical modification of carbon nanotubes with a dendrimer bearing
terminal mercaptoundecahydrododecaborates (Na2B12H11S)
The functionalization of dodecaborates has attracted much attention, both for the development of boron neutron capture therapy(BNCT),where 10B nuclei capture thermal neutrons to emit 7Li nuclei and alpha particles that destroy cancer cells. Increasing focus has
been placed on the conjugation of the thiol‐substituted B12‐cluster mercaptoundecahydro‐closo‐dodecaborate (Na2[B12H11SH]; BSH). Thisis mostly due to the fact that BSH offers great biological advantages, which includes higher boron
content, ionic nature, higher solubility in water, significantly lower toxicity based on its boron content,and its clinical use in the treatment of cancer (BNCT). For a boron delivery agent to be successful in
BNCT, both high tumor‐targeting selectivity and the possibility for in vivo imaging are required. However, reports on the conjugation of BSH with bioimaging agents remain scarce. We have successfully
synthesized a new water‐soluble dendrimer that bears B12‐cluster terminals, with potential applicationsin BNCT. Moreover, the physical modification of SWCNTs with boron-cluster dendrimer furnished
SWCNT/(boron-cluster dendrimer) nanohybrids that exhibit NIR‐I‐to‐NIR‐II fluorescence. Further investigations into the cellular uptake and cytotoxicity of our materials are currently in progress.

Disproportionation-induced solid-state fluorescence in6,13-dihydropentacenes〓 Sr. Asst. Prof.
TAJIMA Tomoyuki

The molecular design of π-conjugated systems is crucial for the development of new functional materials. Nevertheless,reports on π-conjugated systems exhibiting disproportionation-induced photoluminescence changes are relatively rare.
Against this background, we decided to explore the utility of disproportionation reactions for the development of fluorescent chromic materials. The thermally and photolytically induced disproportionation of 6,13-dihydropentacene derivatives
into tetrahydropentacenes and pentacenes results in unique solid-state fluorescence. The fluorescence thereby depends on the molecular structure and themolecular arrangement in the solid state. The molecular structure and conformation in the crystals strongly influence the disproportionation reaction. Upon
heating or photoirradiation of 6,13-dihydropentacene derivatives in the solidstate, the fluorescence color gradually changed from bright blue to red. The solid-state fluorescence behavior induced by disproportionation may serve as an
example for guided molecular engineering, providing fascinating possibilities totune materials for sensing, as well as optical and thermal recording applications.

〓 Research Area : Environmental Polymer Chemistry

Creation of environmentally benign polymerization system and polymer materials
Aromatic polymers are used in various industrial fields
as high-performance materials due to their excellent
properties, such as thermal stability, mechanical properties, or chemical stability. However, processing of thesepolymers is extremely difficult because of their intractability. We have been studied the unique polymerization
system for morphology control of aromatic polymers.
As a result, we obtained various morphologies such as
whisker, ribbon, helical, sphere with dimple, and so on.
This polymerization system and materials are one of theanswer towards sustainable development of society.

Studies on biodegradable polymers with unique topology based on crystallization control〓 Prof.
KIMURA Kunio〓 Assoc. Prof.
YAMAZAKI Shinichi〓 Asst. Prof.
ATARASHI Hironori
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This study conducts the development of high-performance biodegradable polymers with the tunability of physical properties such as mechanical strength and thermal resistance using the uniquetopology of cyclic homopolymer and topological blend polymer having cyclic polymer as a component. The cyclic homopolymer and topological blend polymer are capable of control of crystalline
and entanglement state. The unique morphology and crystallization behavior have been clarified.