标题：Double proton transfer behavior and one-electron oxidation effect in double H-bonded glycinamide-formic acid complex
作者：Li P;Bu YX
作者机构：[Li, P] Institute of Theoretical Chemistry, Shandong University, Jinan 250100, China, Department of Chemistry, Qufu Normal University, Qufu 273165, Ch 更多
通讯作者地址：[Bu, YX]Shandong Univ, Inst Theoret Chem, Jinan 250100, Peoples R China.
来源：The Journal of Chemical Physics
关键词：BARRIER HYDROGEN-BONDS;DENSITY-FUNCTIONAL THEORY;POTENTIAL-ENERGY SURFACE;POST-HARTREE-FOCK;SEMIEMPIRICAL DYNAMICS CALCULATION;ANION MODEL SYSTEM;AB-INITIO DYNAMICS;THYMINE BASE-PAIR;GAS-PHASE;PEPTIDE-BOND
摘要：The behavior of double proton transfer occurring in a representative glycinamide-formic acid complex has been investigated at the B3LYP/6-311++G** level of theory. Thermodynamic and, especially, kinetic parameters, such as tautomeric energy, equilibrium constant, and barrier heights have been discussed, respectively. The relevant quantities involved in the double proton transfer process, such as geometrical changes, interaction energies, and intrinsic reaction coordinate calculations have also been studied. Computational results show that the participation of a formic acid molecule favors the proceeding of the proton transfer for glycinamide compared with that without mediate-assisted case. The double proton transfer process proceeds with a concerted mechanism rather than a stepwise one since no ion-pair complexes have been located during the proton transfer process. The calculated barrier heights are 11.48 and 0.85 kcal/mol for the forward and reverse directions, respectively. However, both of them have been reduced by 2.95 and 2.61 kcal/mol to 8.53 and -1.76 kcal/mol if further inclusion of zero-point vibrational energy corrections, where the negative barrier height implies that the reverse reaction should proceed with barrierless spontaneously, analogous to that occurring between glycinamide and formamide. Furthermore, solvent effects on the thermodynamic and kinetic processes have also been predicted qualitatively employing the isodensity surface polarized continuum model within the framework of the self-consistent reaction field theory. Additionally, the oxidation process for the double H-bonded glycinamide-formic acid complex has also been investigated. Contrary to that neutral form possessing a pair of two parallel intermolecular H bonds, only a single H bond with a comparable strength has been found in its ionized form. The vertical and adiabatic ionization potentials for the neutral complex have been determined to be about 9.40 and 8.69 eV, respectively, wh