Syntheses, Optical Properties, and Theoretical Investigation of Silafluorenes and Spirobisilafluorenes Bearing Electron‐Donating Aminostyryl Arms around a Silafluorene Core

Abstract

pi-Extended silafluorenes and spirobisilafluorenes bearing electron-donating aminostyryl substituents at the 2,7- or 3,6-positions were synthesized by a Horner-Wadsworth-Emmons reaction. The electronic influence of spirocyclic structure and substitution mode of the aminostyryl substituents was investigated by UV/Vis spectroscopy, which indicated the existence of a spiroconjugation effect in the 3,6-substituted spirobisilafluorene. They exhibited moderate to strong fluorescence emission, and the fluorescence properties were compatible with the UV/Vis absorption characteristics, except for the 3,6-substituted spirobisilafluorene, which showed relatively large enhancement of fluorescence quantum yield and Stokes shift. The influence of the spirocyclic structure and substitution mode on the photophysical properties of the silicon compounds was investigated by DFT calculations.

Circularly Polarized Luminescence from Chiral Spiro Molecules: Synthesis and Optical Properties of 10,10′-Spirobi(indeno[1,2-b][1]benzothiophene) Derivatives

“…Indeed, the bonding and antibonding combinations were shown in the HOMO–1 and HOMO, respectively, for each spiro compound (Figure S16). The energy differences between HOMO–1 and HOMO (0.27 eV for 1 ; 0.22 eV for 3 ) are close to the experimental (0.30 eV) and calculated (0.27 eV) spiro splittings of 9,9′-spirobifluorene and much smaller than the HOMO–1/HOMO energy differences of 7 and 8 . These facts clearly indicate the spiroconjugation in 1 and 3 which would induce the red-shifted absorption spectra of 1 and 3 compared to those of 7 and 8 , respectively.…”

Synthesis and Photophysical Properties of Asymmetric Substituted Silafluorenes

“…Dibenzoannulated analogues of silacyclopentadienes, or silafluorenes, have high electron affinities − and are promising potential materials as electron transporters and emitters for fabrication of organic light emitting diodes (OLEDs) and photovoltaic cells. − Silafluorene conjugates are also anticipated to be useful alternatives for expanding the repertoire of traditional fluorescent dyes in many biological assays and fluorescent imaging techniques . Important features of useful fluorophores for such applications include high absorption, high quantum yield, high stability with respect to photobleaching, and compatibility with biological systems.…”

“…We were interested in synthesizing new blue light emitting silafluorenes. With molecular modification, the electronic and optical properties of π-conjugated compounds can be tuned; thus, attaching conjugating substituents to the symmetric silafluorene ring can lead to red shifting, driving the emission maximum from the UV into the blue region . Attaching different groups to the silicon atom in the silafluorene ring also influences the fluorescence quantum yield efficiency …”

Synthesis and Photophysical Studies of Dibenzophosphole Oxides with D–A–D Triad Structures

“…In previous efforts, approaches have been developed for the preparation of dibenzosilole derivatives possessing two 2‐[4‐dimethylaminophenyl]vinyl or phenothiazin‐10‐yl groups using dibromide precursors , . We utilized this general strategy for the synthesis of the target DBPO derivatives.…”