Unité de Chimie Physique Théorique et Structurale, Namur Institute of Structured Matter, Université de Namur, B-5000 Namur, Belgium.
Departamento de Física, Universidade Federal Rural do Rio de Janeiro, 23890-0000 Seropédica, Rio de Janeiro, Brazil.
J Phys Chem A. 2023 Apr 13;127(14):3096-3103. doi: 10.1021/acs.jpca.3c00090. Epub 2023 Apr 5.
Sequential quantum mechanics/molecular mechanics (QM/MM) calculations combining the average solvent electrostatic configuration (ASEC) and the free energy gradient method are employed to locate minimum structures of α- and β-alanine in a water environment. Herein, we study the solvation effects in the nuclear magnetic resonance (NMR) spectroscopy, vibrational circular dichroism (VCD) spectroscopy, and electronic circular dichroism (ECD) spectroscopy of dl-α-alanine and β-alanine molecules. Our results point out that the ASEC-FEG (average solvent electrostatic configuration with the free energy gradient) method is a suitable approach for finding equilibrium structures of the alanine molecules in aqueous solution. Its accuracy is checked by comparing the optimized structures with those reached by the polarizable continuum model (PCM) and via experimental data. NMR parameters and vibrational and electronic UV-vis spectra are computed with a remarkable agreement with their corresponding experimental values.
采用结合平均溶剂静电构型（ASEC）和自由能梯度方法的序贯量子力学/分子力学（QM/MM）计算，对α-和β-丙氨酸在水环境中的最低结构进行定位。在此，我们研究了 dl-α-丙氨酸和β-丙氨酸分子在核磁共振（NMR）光谱、振动圆二色性（VCD）光谱和电子圆二色性（ECD）光谱中的溶剂化效应。我们的结果表明，ASEC-FEG（平均溶剂静电构型与自由能梯度）方法是一种适合寻找丙氨酸分子在水溶液中平衡结构的方法。通过与极化连续模型（PCM）和实验数据得到的优化结构进行比较，验证了其准确性。计算得到的 NMR 参数以及振动和电子 UV-vis 光谱与相应的实验值吻合良好。
