Kinetics of photo-oxidation of Pd(II) complexes with Thiosalycylic acid and1,10-phenanthroline

The complexes of the formula [Pd(phen)(tsa)] and [Pd(tsa)2] (where phen= 1,10-phenanthroline and tsa = dianion of thiosalicylic acid) were synthesized replacing solvent DMSO by water, in order to develop a cleaner chemical synthetic process. Photosensitivity of the synthesized complexes has been studied. A series of photochemical experiments has been performed to investigate the role of these complexes in photo-oxygenation reactions. Study of photolysis of these complexes suggests the involvement of singlet oxygen which is further confirmed by using sodium azide as quencher of 1 O2. Progress of the reaction is monitored by UV-visible spectrophotometry. The rate constant and yield of singlet oxygen has been determined using DPBF(1,3diphenylisobenzofuran) as probe . It has been observed that the type of solvent used in synthesis does not affect its photochemical behavior which encourages the use of greener solvent like H2O for synthetic purposes. These Pd(II) complexes act as chemical quenchers of singlet oxygen and undergo self-sensitized photo-oxidation. The photochemical behavior of these complexes can be exploited for biological application as Pd(II) complexes are biologically active.