Studies On The Reaction Mechanism Of Valine Optical Isomerization And Which Interaction With Hydrotalcite And Montmorillonite Laminates

The photoreaction mechanism of the solid and gaseous L-valineoptical isomerization was in-depth studied by the density functionaltheory (DFT) and ab initio molecular orbital theory. Discussed thereaction mechanism was effected by the effect of solvent, intercalatedMg-Al LDHs which with the positively charged and modified MMT witha negative charged. The calculated results and the experimental data ofL-valine inserted layer hydrotalcite and L-valine modifiedmontmorillonite was compared.First, The geometric parameters of reactant, product, intermediates,and transition states, as well as the reaction energy barriers, on thereaction paths in S0and T1states are optimized at the B3LYP and MP2levels using the6-311++G(d, p) basis sets. The equilibrium geometries ofthe S1state of valine are optimized using time dependent density functionaltheory (TD-DFT) at the B3LYP/6-311++G(d, p) level. From the analysisof each geometric stationary point on the reaction path, the photoreactionmechanism of L-valine optical isomerization is proposed. The reaction proceeds via hydrogen transfer with the help of carbonyl O or amino Natom in the excited state.Secondly, the effect of solvent to the reaction mechanism of isomerswas discussed by PCM method. Determined the effect of solvent to theenergies of the optical isomers on the reaction pathway had decreased.Inorganic polar solvent was more than organic non-polar solvents on theeffect of reaction energy. Effect of H2O solvent to the energy barrier onthe second reaction path had a certain influence.Thirdly, Geometric parameters of the host layers of Mg-Al LDHs,L-valine anions and product of adsorption model were optimized at thelevel of B3LYP and B3PW91methods on the basis level of6-311++G(d,p). The feasibility of the selected product adsorption model instead of thetrue model to the theoretical analysis was verified by compared infrared(IR) spectra of calculated the vibrational frequencies and the ultraviolet(UV) spectra of calculated the vertical excitation by TD-DFT with IR andUV spectra of experimentally measured of product of L-valineintercalated hydrotalcite. The photoreaction mechanisms of L-valineoptical isomerization on two possible paths were inhibited by Mg-AlLDHs was proposed by the analysis of the Mulliken charge populationanalysis and the host-guest interaction.Finally, Geometric parameters of the host layers of MMT, L-valineanions and product of adsorption model were optimized by PM3method. Also the feasibility of the selected product adsorption model instead of thetrue model to the theoretical analysis was verified by compared the theorycalculation with the experimentally data. There was basically no effect onthe photoreaction mechanisms of L-valine optical isomerization on twopossible paths by MMT was proposed by the analysis of the Mullikencharge population analysis and the host-guest interaction.