名称:
Preparation and study of amino acid (DL-leucine, L-isoleucine, L-histidine) Schiff bases with ethyl-α-ketocyclopentylcarboxylate and the corresponding copper(II) complexes
摘要:
Amino acid Schiff bases with ester function K(Rleu) . 2H2O (1), K(Rile) . 2H2O (2), K(Rhis) . H2O (3) (Rleu, Rile and Rhis represent the Schiff base Of DL-leucine, L-isoleucine and L-histidine, and ethyl-alpha-ketocyclopentylcarboxylate) were synthesized. Compounds 1, 2 and 3 were characterized by H-1 NMR spectroscopy. The copper(II) complexes, Cu(Rleu') . H2O (4), Cu[Rile'] . H2O (5) and Cu(Rhis') . 2H2O (6), were obtained with the N-deprotonated Schiff bases (Rleu', Rile' and Rhis'). The COO stretching bands in their IR spectra suggest that the carboxylate acts as a monodentate group when binding with copper. The temperature dependence of the susceptibility for 6 may be fit to the Curie-Weiss expression chi = 0.32/(T-26.2) emu mol-1 K-1. The dehydration process of 6 leads to the anhydrous compound, enthalpy (53 +/- 2kJ mol-1) and activation energy (82 +/- 5 kJ mol-1).