σ-σ conjugation Across Si─O─Si Bonds.

Polysiloxanes and silsesquioxanes (SQs) are known to be insulating materials. We describe here polysiloxane copolymers where this is not the case. Thus,MeVinylSi─O─SiMeVinyl/Br-Ar-Br copolymers exhibit conjugation via Si─O─Si bonds contrary to the widespread understanding that such linkages must be insulating.

Conjugation through Si-O-Si bonds, silsesquioxane (SQ) half cage copolymers, extended examples SiO/SiO units: multiple emissive states in violation of Kasha's rule.

We previously reported that phenyl- and vinyl-silsesquioxanes (SQs), [RSiO] (R = Ph or vinyl) functionalized with three or more conjugated moieties show red-shifted absorption- and emission features suggesting 3-D conjugation a cage centered LUMOs. Corner missing [PhSiO](OSiMe) and edge opened, end capped [PhSiO](OSiMe) (double decker, DD) analogs also offer red shifted spectra again indicating 3-D conjugation and a cage centered LUMO. Copolymerization of DD [PhSiO](OSiMevinyl) with multiple R-Ar-Br gives copolymers with emission red-shifts that change with degree of polymerization (DP), exhibit charge transfer to FTNCQ and terpolymer averaged red-shifts suggesting through chain conjugation even with two (O-Si-O) end caps possibly a cage centered LUMO.