Photoinduced Electron Transfer from Meso-Tetrakis (N-methylpyridyl)porphyrin (TMPyP) to Colloidal CdS

Abstract

Abstract A stable colloidal CdS nanoparticles were prepared. The dynamics of photoinduced interaction between meso-tetrakis(N-methylpyridyl)porphyrin (TMPyP) and colloidal CdS were studied using absorption, steady state, time resolved fluorescence and FT-IR spectral measurements. The apparent association constant (K app) of TMPyP-CdS obtained from absorption spectral changes is 1.07×103 M−1. The K app value of TMPyP-CdS as determined from fluorescence spectra is 1.34×103 M−1, which matches well with that determined from the absorption spectra changes. These data indicate that there is an interaction between TMPyP and colloidal CdS nanoparticle surface. The dynamics of photoinduced electron transfer from TMPyP to the conduction band of colloidal CdS nanoparticle has been observed and the mechanism of electron transfer has been confirmed by the calculation of free energy change (ΔG et) by applying Rehm-Weller equation as well as energy level diagram. Lifetime measurements gave the rate constant (k et) for electron injection from the excited state TMPyP into the conduction band of CdS is 3.21×108 s–1.