Effects of Substitution on Solid-State Fluorescence in 9-Aryl-9-methyl-9H-9-silafluorenes.

Molecules

Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

Published: September 2016

Aromatic groups were incorporated into 9H-9-silafluorene units at the 9-position (mono-9H-silafluorenes) and 9,9'-positions (di-9H-9-silafluorenes). The aryl substituents showed weak conjugation to the 9H-9-silafluorene for 9-aryl substituted ones 1-7 and a 9,9'-phenylene substituted one (compound 8) and they exhibited similar absorption and emission spectra. The 9H-9-silafluorene 10 containing a 5,5'-(2,2'-bithiophenyl) group showed a significantly red-shifted absorption and fluorescence maxima in the solid-state. Single-crystal X-ray diffraction studies found J-type aggregated structures formed by intermolecular CH-π interactions (ca. 2.6-2.7 Å). Density functional theory (DFT), time-dependent DFT (TD-DFT), and configuration interaction single (CIS) calculations were conducted to explain the observed optical properties.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6274553PMC
http://dx.doi.org/10.3390/molecules21091173DOI Listing

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