The Study Of Infrared And Raman Spetra Of Amino Acid Transition Metal Complex

The amino acid is a basic structural unit composing the protein and enzyme in living body.The metal complex with amino acid is participating in various metabolism and physiology biochemistry process in human body,so it plays an important role in life process.Therefore,the study on coordination mechanism of metal complex with amino acid plays an important role of the biological effect of metal ions and the life activity of complicated biological system.The complex of L-glycine,L-alanine,L-threonine with zinc were studied in this paper.The Infrared and Raman spectrum of complexes were determined,the structure and coordination mechanism of metal complexes with amino acids were discussed.By the determination of amino acid zinc complexes' conductance,the influencing factors of reaction time and reaction temperature have been discussed,and the coordination ratio at isoelectric point has been confirmed as 2:1(amino acid:metal ion).Following these conclusions,the influence such as different pH value and co-existed negative ions to amino acid zinc system was discussed.Then the coordination law and reaction mechanism of amino acid zinc complex were generalized.Besides,the copper(Ⅱ) amino acid complex,the iron(Ⅲ)amino acid complex have been studied in the paper.The results can be concluded as follow:(1)The amino acid coordinated with Zn²⁺by -COO^- at isoelectric point.The L-glycine and L-alanine coordinated with Zn²⁺by the oxygen atom of carboxyl in monodentate mode,however,the theronine coordinated in bidentate mode.The amino acid zinc complex has the configuration of regular tetrahedron.(2)The amino acid and zinc ion have different states with different pH value.When the pH value is 1.0,the amino acid can not coordinate with Zn²⁺,because both -NH₃⁺ and -COOH group are not containing lone pair electrons.When amino acid exists in R-CH₂-CH(NH₂)-COO^- at pH 13.0,the -NH₂ and -COO^- can provide lone pair electrons which can coordinate with Zn²⁺to form chelating ring complex.(3)When the amino acid coexisted with different negative ion (SO₄^2-,NO₃^-),Both SO₄^2-and NO₃^- can react with Zn²⁺as monodentate ligand,and formed the mixed ligand complexes.(4)The amino acid coordinated with copper(Ⅱ)and iron(Ⅲ)by -COO^- at isoelectric point.And the oxygen atom of carboxyl was monodentate mode in amino acid copper complex.The complex was four-coordinated in a square planar configuration with the hybridization of dsp².And the oxygen atom of carboxyl was monodentate mode in glycine-iron and alanine-iron complex,it was bidentate mode in theronine-iron complex.The complex was four-coordinated in a regular tetrahedron configuration with the hybridization of sp³.(5)The results showed that the stabilization of amino acid copper (Ⅱ)complex is better than the other two complexes.In copper complex the bond M-O is the strongest,and the stretching vibration frequency of M-O is low.