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Solid‐State Photochromism by Molecular Assembly of Bis‐ o ‐carboranyl Siloles
Author(s) -
Cho YangJin,
Kim SoYoen,
Lee JieWon,
Han WonSik,
Kim Chul Hoon,
Son HoJin,
Kang Sang Ook
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901305
Subject(s) - photochromism , amorphous solid , solid state , crystallography , materials science , crystal (programming language) , photochemistry , benzene , chemistry , organic chemistry , computer science , programming language
A new type of solid‐state photochromism was observed in an AB 2 ‐type molecular assembly comprising a central silole and two peripheral o ‐carborane units, and in this assembly, depending on the assembling positions of those units at the adjoining benzene ring, two different regioisomers were formed: Si‐ m ‐Cb and Si‐ p ‐Cb . Each isomer showed different solid‐state photochromism depending on its solid‐state molecular conformation and was either in the crystalline or amorphous state. The crystals of each meta ‐ or para ‐isomer, C Si‐ m ‐Cb or C Si‐ p ‐Cb , showed yellow or blue emission, and mechanically grinding those crystals into amorphous powders of A Si‐ m ‐Cb and A Si‐ p ‐Cb , switched their emissions to blue and yellow, respectively. Photophysical studies revealed that the electronic interaction between silole and o ‐carborane units determined the emission color. The crystal and DFT‐optimized structures each account for the crystalline and amorphous structures, respectively, and are correlated well with the electronic interactions in the molecular assembly in the solid state, thus enabling the prediction of the solid‐state molecular conformational change.