Studies on the fluorescence quenching of polysilane copolymers by chlorohydrocarbons

The room-temperature solution fluorescence quenching of polysilane copolymers by chlorohydrocarbons such as CCl₄, CHCl₃, C₂Cl₆, and Cl₂CHCHCl₂ was studied. The existence of dynamic quenching was preliminarily demonstrated by the experiment of fluorescence lifetime quenching. The fluorescence quenching data were in conformity with the equation: F₀/F = (1+K_SVQ])exp(NVQ]), where F and F₀ are the fluorescence intensity with and without the addition of quencher, K_SV is the Stern-Volmer constant, Q] is the quencher concentration, N is the Avogadro constant, and V is the volume of the active sphere. The fluorescence quenching by the first three chlorohydrocarbons was attributed to the contemporaneous effect of dynamic quenching and static quenching. There exists, at least mathematically, a critical quencher concentration Q]_C. When the quencher concentration Q] < Q]_C, the fluorescence quenching is dominated by the dynamic quenching part; when Q] > Q]_C, it is dominated by the static quenching part. However, the fluorescence quenching by Cl₂CHCHCl₂ was attributed to only static quenching. Furthermore, it was proposed that the dynamic quenching may be related with the electrical positivity of the central carbon nucleus of the quenching molecules while the static quenching may be caused by the “outside heavy atom effect” of the Cl element. © 1996 John Wiley & Sons, Inc.