New Schiff Base and Its Zn^2+ Metallopolymer: Synthesis, Characterization and Solid-State Conductivity

The N, N’-bis-pyridine-4-ylmethylene-1,2-diamine (Pyen) was prepared by a reaction of ethylene diamine and 4- pyridine carbaldehyde. The DA was synthesized by a reaction of 4- chloromethyl salicylaldehyde and Pyen. The new ionic Schiff base polymer ligand (L) was synthesized by a reaction of DA and ethylene diamine in methanol at refluxed conditions. The ionic Zn^2+mettallo Schiff base polymer was synthesized by reaction of L and ZnCl2 in methanol at refluxed conditions. The synthesized compounds were characterized by various analytical and spectral methods. The chemical composition and functional group identification of the synthesized compounds were confirmed by CHN analysis, FT-IR, 1H-NMR spectroscopy, and mass spectrometry. The molecular weight of the L and ZnL was determined by size exclusion chromatography with the results of the Mw= 6441.4 and 14212 for L and ZnL, respectively. The XRD pattern of the L and ZnL exhibited an amorphous character with low crystallinity. The SEM images showed shapeless plates with narrow valleys in the case of L and deep pores in the case of ZnL. The TEM images revealed a cluster of scaffold structures or agglomerated structures of the polymers. The solid-state conductivity of the L and ZnL was studied and the results showed that the conductivity increased by increasing the temperature from 300K to 400K. This behavior confirms the semiconducting properties of L and ZnL. The calculated solid-state conductivity of L in this temperature range (4.18×10^-10-1.04× 10^-5 Ω−1 m^−1) is higher than the calculated solid-state conductivity of ZnL(1.45×10^-11-3.12×10^-9 Ω−1 m^−1) whereas the calculated activation energy (of conductivity) for ZnL (0.19 ev) is lower than the calculated activation energy of conductivity (0.29ev) for L.