Synthesis of inorganic complexes derived from 4- amino-5-(pyridyl)-4H 1,2,4 triazole-3-thiol and study their photochemical stability with polystyrene

Five transition metal complexes of Ni(II), Cu(II), Zn(II),Cd(II) and Sn(II) with {4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol},as a ligand (L) has been prepared in alcoholic medium.These complexes are:
1. Bis(4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol) Nickel(II), Ni(L)2 . 2. Bis(4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol) Cupper(II), Cu(L)2. 3. Bis(4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol) Zinc(II),Zn(L)2.4. Bis(4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol)Cadmium(II),Cd(L)2.5.Bis(4-amino-5-(pyridyl)-4H-1,2,4-triazole-3-thiol)Tin(II), Sn(L)2.Theligand (L)and its metal complexes were characterized quantitatively and qualitatively by using: FTIR,UV-visible spectroscopy,1H and 13C NMR,
magnetic susceptibility and conductivity measurements.This ligand act as bidentate that coordinated to the metal ions through sulphur and nitrogen of amine group.According to the spectral data of the complexes a tetrahedral geometry was
suggested for these complexes except Cu(II) complexes which exhibit a square structure.In this work the prepared complexes of 4- amino-5-(pyridyl)-4H 1,2,4
triazole -3- thiol were used to enhance the photostabilization of Polystyrene (PS). Polystyrene has been mixed with these complexes in chloroform solvent which containing concentration of complex 0.5 % by weight, which produced by the casting method from chloroform solvent.The photostabilization of polystyrene films were studied at room temperature under irradiation of light λ=365 nm wave length with intensity 20.6*10-9 Ein Dm-3 S-1.The photostabilization activity of these compounds was determined by monitoring the carbonyl (ICO) and hydroxyl (IOH) indexes, weight loss method with
irradiation time. It was found that the (ICO) and (IOH) indexes values increased with irradiation time and this increase depend on the type of additives. The surface morphology for these films was studied during irradiation time.The changes in viscosity average molecular weight of PS with irradiation time were also tracked (using chloroform as a solvent). The quantum yield of the chain scission (Φcs) of
these complexes in PS films was also evaluated.
The following trend is obtained for the photostabilization effect on PS films in presence of additives as shown below: Sn(L)2,Cd(L)2,Ni(L)2, Zn(L)2, Cu(L)2 Increasing the photostability According to the experimental results obtained, mechanisms were suggested, depending on the structure of the complexes.