Synthesis, Optical Properties, and Crystal Structures of Dithienostannoles

Abstract

Reactions of dichlorodiphenylstannane with 3,3′-dilithio-5,5′-bis­(trimethylsilyl)-2,2′-bithiophene and 3,3′-dilithio-2,2′-di­(benzo­[<i>b</i>]­thiophene) gave 1,1-diphenyl-3,6-bis­(trimethylsilyl)­dithienostannole (<b>DTSn1</b>) and di­(benzo­[<i>b</i>]­thieno)-1,1-diphenylstannole (<b>DTSn2</b>), respectively. Optical properties of the dithienostannoles and the results of DFT calculations on a model suggested an in-phase interaction between Sn σ* and bithiophene π* orbitals, stabilizing the LUMO. Interestingly, <b>DTSn1</b> showed crystallization-enhanced emission and the photoluminescence (PL) quantum yield of the crystals was determined to be higher by about 20 times than that in the amorphous and solution phase, while <b>DTSn2</b> exhibited moderate PL efficiency both as crystals and in solution. Crystal structures of the dithienostannoles were determined by X-ray diffraction studies, which showed the differences in the molecular packing between <b>DTSn1</b> and <b>DTSn2</b>, being responsible for their different PL properties in the crystal state