Photochemistry of Locally Excited and Intramolecular Charge Transfer States of a Disilane Bearing a Cyclic Arylethenyl Electron Acceptor Substituent

Abstract

1-(p-cyanophenyl)-2-(pentamethyldisilanyl)cyclopentene (1) exhibits a fluorescence at λ>400 nm, which strongly shifts to the red with increasing polarity of the solvent. The corresponding solvatochromic plot is indicative of an emissive, lowest energy charge-transfer (CT) state. Stern-Volmer quenching of the fluorescence by dilute methanol in pentane gives a linear plot with a unit intercept and a slope k Q τ ct =0.70. Quenching is accompanied by formation of (arylcyclopentenyl)dimethylsilane 7, the major product observed upon photolysis of 1 in the presence of methanol. This is evidenced by the linear double-reciprocal plot of quantum yields of 7 versus methanol concentration, which gives a k Q τ ct value in agreement with fluorescence quenching