Effect of TiO2 nanoparticles on some photophysical characteristics of ketocyanine dyes

Abstract

The effect of titanium dioxide (TiO₂ ) nanoparticles (NPs) on photophysical characteristics of 2,5-di[(E)-1-(4-dimethylaminophenyl) methylidine]-1-cyclopentanone (2,5-DMAPMC) and 2,5-di[(E)-1-(4-diethylaminophenyl)methylidine]-1-cyclopentanone (2,5-DEAPMC) ketocyanine dyes has been studied using absorption, steady-state and time-resolved fluorescence spectroscopy. The magnitudes of association constants determined based on modified absorption spectrum of dyes due to the presence of TiO₂ NPs indicate the interaction of TiO₂ NPs with dye molecules. The quenching of fluorescence intensity of dyes by TiO₂ NPs is observed and it follows linear Stern-Volmer (S-V) equation. The magnitude of quenching rate parameter suggests the involvement of static quenching mechanism. The involvement of electron transfer process in reducing fluorescence intensity of dyes has been discussed. Also, varying influence of TiO₂ NPs on two dyes is explained based on the presence of different alkyl substituent in two dyes.

Keywords: TiO2 nanoparticles; electron transfer; fluorescence quenching; ketocyanine dye.