Synthesis of polymer anchored N,N′-bis(3-allyl salicylidene)o-phenylenediamine cobalt(II) Schiff base complex and its catalytic activity for decomposition of hydrogen peroxide

The anchoring of N,N-bis(3-ally salicylidene)o-phenylenediamine cobalt(II) Schiff base complex on polymer support has been carried out by suspension copolymerization of synthesized N,N'-bis(3-allyl salicylidene)o-phenylenediamine monomer Schiff base (N,N'-BSPDA) with styrene (St) and divinylbenzene (DVB) using azobisisobutyronitrile (AIBN) as initiator in presence of poly(vinyl alcohol). The polymer anchored Schiff base (N,N'-BSPDA) was subsequently loaded with cobalt(II) ions. The cobalt(II) ions loading, degree of cross-linking and swelling in prepared beads have shown dependence on the amount of DVB taken in the reaction mixture. The amount of N,N' -BSPDA monomer Schiff base and its arrangement in cross-linked beads have also shown dependence on the amount of DVB taken in the reaction mixture. The cross-linked beads (Type-III) obtained at 1.50 mmol of DVB have shown highest loading for cobalt(II) ions (1.18 mmol g-(1) of beads) due to maximum amount of N,N'-BSPDA monomer Schiff base on these beads (1.74 mmol g(-1) of beads). The amount of DVB taken in the reaction mixture has shown significant effect on porosity, internal surface area (S-BET), average pore diameter (b) and degree of swelling in prepared beads. The IR, UV and magnetic measurements have provided sufficient evidences for square planar geometry of N,N'-BSPDA cobalt(II) complex both in homogeneous and heterogeneous conditions. The complexation of cobalt(II) ions on polymer anchored N,N' -BSPDA monomer Schiff base has shown a significant increase in its thermal stability. The catalytic activity of polymer supported N,N'-BSPDA cobalt(II) complex was evaluated under different experimental conditions and its activity was compared with unsupported analogue. The energy of activation for decomposition of hydrogen peroxide with supported N,N'-BSPDA cobalt(II) complex has been found to be low (36.04 kJ mol(-1)) in comparison to unsupported one (61.27 kJ mol(-1)). To explain experimental results, a suitable rate expression has been derived. (C) 2003 Elsevier Science B.V. All rights reserved.