KCS

A series of 2,3,4,5-tetraphenylsiloles, with a four- to six-membered silacyclo alkyl substituent at the 1,1′-position, has been prepared by a one-pot synthesis of dilithium diyne with the corresponding silacycloalkyl dichlorosilane precursors. The photophysical properties of the silacycloalkyl siloles were examined to elucidate the structure–photophysical property relationship arising from variation of the exocyclic ring size. Indeed, the size of the exocyclic silacycloalkyl ring at the 1,1′-position affected the maximum peaks in the absorption and emission spectra, with systematic blue shifts being observed with increasing exocyclic ring size. A sequential elevation of the LUMO levels was monitored by observing increases in the reduction potential, as seen in the cyclic voltammograms (CVs), with increasing exocyclic ring size. In addition, due to the formation of exocyclic rings, an enhanced thermal stability was observed based on DSC measurements, showing that silacyclopentylsilole exhibits the highest Tg value in the series.