Study On Phase Chemistry And Thermochemistry Of The Complexes Of Zinc Salts With Amino Acids

The phase equilibrium properties of ternary systems ZnSO4-Try/Leu/Val/Thr-H2O and Zn(NO3)2-Try/Leu/Val/Thr-H2O have been studied at 25℃. The experimental results indicated that ZnSO4-Try/Leu/Val/Thr-H2O systems are simple systems, which do not exist any new compound, and ten new incongruty soluble complexes exist in Zn(NO3)2-Try/Leu/Val/Thr-H2O systems as follows: Zn(Try)(NO3)2·2H2O,Zn(Try)2(NO3)2·H2O,Zn(Leu)(NO3)2·2H2O,Zn(Leu)2(NO3)2·H2O,Zn(Val)(NO3)2·2H2O,Zn(Val)2(NO3)2·H2O,Zn(Val)3(NO3)2·H2O,Zn(Thr)(NO3)2·2H2O,Zn(Thr)2(NO3)2·H2O,Zn(Thr)3(NO3)2·H2O, which are all not reported in any literature.Under the guide of phase equilibrium results, the ten complexes of above have been prepared in water. The solid complexes Zn(Leu)SO4·1/2H2O,Zn(Val)SO4·H2O,Zn(Thr)SO4·H2O,Zn(Try)2,Zn(Leu)2,Zn(Val)2·H2O are prepared according to literature. The stick-shaped crystal of complex Zn(Val)2·H2O have been obtained in the room temperature. Its structure is being determined by single crystal X-diffraction analysis. The zinc is chelated by two molecules valine through amino nitrogen and carboxyl oxygen, and coordinated by water molecule oxygen atom. The primary coordination around zinc is a square pyramid.The complexes have been studied through chemical analysis, elemental analysis, XRD, IR, TG-DTG and DSC. According to thermal analysis data, the non-isothermal kinetic data(E-the apparent activation energy, A-the pre-exponential factor) were analyzed by means of integral and differential methods. The possible dewater reaction mechanism for some complexes was investigated.The solution enthalpies of complexes have been determined by using a microcalorimeter at 25℃ water and 37℃ HCl solution. According to Hess law, the standard enthalpies of formation of Zn(AA) have been calculated.The combustion energies of some complexes have been determined by using a precision rotating-bomb calorimeter. The standard enthalpies of combustion and standard enthalpies of formation of complexes have been calculated.