Role of mixed ligand Pd(II) and Pt(II)complexes in photooxygenation reaction

Abstract

Mixed ligand complexes of the formula (M (phen) bdt) where M= Pd (II) or Pt(II), phen =1,10- phenanthroline and bdt =1,2-benzenedithiolate have been synthesized and studied as photosensitizers of singlet molecular oxygen ( 1 O2) production. It was observed that, Pt (II) complex shows a better photosensitizing ability as compared to its Pd (II) analogue. However, both Pd (II) and Pt (II) complexes act as chemical quenchers of 1 O2, resulting in their photooxidation shown by decay of the respective complex. ThusPt (II) complex undergoes selfsensitizedphotooxidation by 1 O2. The solvent dependence of this reaction is undertaken by performing the experiment using pure DMF(dimethyl formamide)and 10% H2O in DMF as solvent. The comparison of rate of decay of the Pt(II)and Pd(II) complexes show enhancement of the reaction in presence of water. The decay of the complex was monitored by recording the difference absorption spectra of the complex in the visible region after definite irradiation times. Involvement of 1 O2 is further supported by quenching studies of this reaction using NaN3 as physical quencher of 1 O2.