title: 4,7-Bis[3-(dimesitylboryl)thien-2-yl]benzothiadiazole: Solvato-, Thermo-, and Mechanochromism Based on the Reversible Formation of an Intramolecular B-N Bond.
abstract: 4,7-Bis-[3-(dimesitylboryl)thien-2-yl]benzothiadiazole (1) and monoborylated derivative 2 were synthesized and their chromic behavior was investigated. Photophysical measurements, single-crystal XRD analysis, and theoretical calculations revealed that an intramolecular B-N coordination bond formed reversibly. The equilibrium of this reversible bond formation depends on the solid-state structure, solvent, temperature, and mechanical forces, and leads to significant changes in the electronic structure and chromic behavior of these molecules. The responsiveness toward external stimuli, resulting in the reversible formation of open and closed forms of this system, is achieved through weak intramolecular B-N coordination bonds induced by the steric bulk of the mesityl groups on the boron centers.
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimogawa
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Yoshikawa
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Aramaki
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Michihisa
authors.initials: M
authors.lastname: Murata
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.|Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
authors.forename: Atsushi
authors.identifier: http://orcid.org/0000-0003-1430-0947
authors.initials: A
authors.lastname: Wakamiya
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
authors.forename: Yasujiro
authors.initials: Y
authors.lastname: Murata
keywords: boron; coordination bonds; mechanochromism; solvent effects; steric effects