Synthesis, Characterization And Bio-activity Of Cupric Complexes Derived From L-lysine And Its Schiff Base

The excellent capabilities of L-lysine and its Schiff base in biology, medicine, catalysis and material have been widely reported. In this paper, copper lysine and lysine Schiff bases and their cupric complexes have been prepared using L-lysine, cupric chloride, salicylaldehyde and anisaldehyde as raw materials.Copper lysine was synthesized from L-lysine and cupric chloride using NH₃·H₂O as pH controlling agent. Single factor experiments was used to get the optimal synthesis process: nCuCl₂:nLys=3:5, pH=8, synthesis temperature 45℃, reaction time 60min and the yield was 71%. The copper lysine was blue powder and the melt point was 227.3℃-227.5℃. It had a good solubility in water and was insoluble in ethanol, ether and other organic solvent.The compositions of the products were characterized by element analysis, IR spectra, Electronic spectra, Fluorescence Spectrum and TG&DTG methods. The possible structures of the LSLK, LSLK cupric complex, LALK and LALK cupric complex have been discussed as C₁₃H₁₇N₂O₃K (L₁), Cu (L₁)·3H₂O, C₁₄H₁₈N₂O₃K(L₂) and Cu(L₂)₂.Combinating Achar differential and Coats-Redern integral method which fits the thirty kinetic equations, the calculating program of thermal decomposition for complexes was designed. The kinetic equation of corresponding kinetic parameters was obtained. The kinetic parameters include E, A, order of reaction and correlationcoefficient etc. The activation entropyâ–³S^≠and activation free-energyâ–³G^≠forsome thermal decomposition steps were also calculated.The thermal decomposition kinetic function of LALK cupric complex in step(3) may be expressed as f(α)=l/4(l-α)[-ln(l-α)]^-3, the kinetic equation of thermaldecomposition: dα/dt = A·e^-E/RT·f(α)=A·e^-E/RT·1/4(1-α)[-ln(1-α)]^-3, E = 2072 kJ/mol, lnA=479.3,r = 0.9946,â–³S^≠=3735 J·K^-1·mol^-1,â–³G^≠=153.4 kJ·mol^-1.In this paper, the activity on O₂ ^-·of the products were studied. Results showed that all of the both products may inhibit the formation of O₂^-·.The inhibitory capacity activities to O₂^- may be described as: Copper lysine > LSLK cupric complex >LSLK> LALK> LALK cupric complex; IC₅₀ of the products was: LSLK cupric complex≈LSLK> Copper lysine > LALK> LALK cupric complex.