Synthesis, characterization, electrical conductivity, and catalytic studies of some coordination polymers of salen-type schiff base

Abstract

Coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the salen-type Schiff base 4,4′-bis[(N-ethanesalicylaldehydediamine-5)azo]biphenyl have been prepared and characterized by elemental analyses, IR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. Thermogravimetric analysis confirms the coordination of H2O in complexes. The 1H NMR spectrum of ligand clearly indicates the presence of OH and azomethine groups. The octahedral geometry have been suggested for Mn(II), Fe(II), Co(II), and Ni(II) complexes, and square planar Cu((II), whereas tetrahedral is suggested for Zn(II) and Cd(II) polychelates. Thermal data have been analyzed for kinetic parameters by both Coat-Redfern and Broido methods. Solid-state dc conductivity of ligand and its polychelates was measured in their compressed pellet form over 313–413 K temperature range. Solidstate conductivity lies in the range 4.361 × 10−11 to 7.241 × 10−10 Ohm−1 cm−1 indicating their semiconducting behavior. Oxidation of styrene with selected catalysts was tested using H2O2 as an oxidant.