Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd, Iran.
J Phys Chem B. 2012 Oct 18;116(41):12552-7. doi: 10.1021/jp3054229. Epub 2012 Oct 8.
Electrode potential and thermodynamic parameters of the electrochemical reaction of L-DOPA in aqueous solution are obtained experimentally by cyclic voltammetry method and also calculated theoretically using accurate ab initio calculations (G3MP2//B3LYP) along with the available solvation model of CPCM. The pH dependence of the redox activity of L-DOPA in aqueous solution at temperatures in the range of 10-30 °C was used for the experimental determination of the standard reduction potential, changes of entropy, enthalpy, and Gibbs free energy for the studied reaction. The experimental formal redox potential of the two-proton-two-electron reduction process was obtained to be 0.745 V versus standard hydrogen electrode (SHE). The theoretical and experimental values (0.728 and 0.745 V) for the standard electrode potential of L-DOPA are in agreement with each other. The difference between the peak potential of the L-DOPA and the products, which are produced by chemical reactions, has been measured experimentally and also calculated theoretically. There is also an agreement between experimental and theoretical potential difference. Also in this work, the changes of thermodynamic functions of solvation are calculated from the differences between the solution-phase experimental values and the gas-phase theoretical values.
通过循环伏安法实验获得了 L-DOPA 在水溶液中的电极电势和电化学反应的热力学参数，并使用精确的从头算（G3MP2//B3LYP）计算方法和 CPCM 可用的溶剂化模型进行了理论计算。在 10-30°C 的温度范围内，研究了 L-DOPA 在水溶液中的氧化还原活性随 pH 的变化，用于实验测定标准还原电势、反应熵、焓和吉布斯自由能的变化。实验得到的二质子二电子还原过程的实验形式氧化还原电势为 0.745V 相对于标准氢电极（SHE）。L-DOPA 的标准电极电势的理论和实验值（0.728 和 0.745V）彼此一致。通过实验测量并通过理论计算也确定了 L-DOPA 峰电位与化学反应产生的产物之间的电位差。实验和理论电位差之间也存在一致性。此外，在这项工作中，还通过比较溶液相实验值和气相理论值之间的差异，计算了溶剂化热力学函数的变化。
