Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695 015, Kerala, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Oct;96:10-7. doi: 10.1016/j.saa.2012.04.062. Epub 2012 May 9.
Vibrational spectral analysis and quantum chemical computations based on density functional theory (DFT) have been performed on the organic crystal L-prolinium picrate (LPP). The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of LPP have been investigated using B3LYP method. The calculated molecular geometry has been compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA 4 program. The various intramolecular interactions confirming the biological activity of the compound have been exposed by natural bond orbital analysis. The distribution of Mulliken atomic charges and bending of natural hybrid orbitals associated with hydrogen bonding also reflects the presence of intramolecular hydrogen bonding thereby enhancing bioactivity. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicates electron transport in the molecule and thereby bioactivity. Vibrational analysis reveals the presence of strong O-H···O and N-H···O interaction between L-prolinium and picrate ions providing evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity.
基于密度泛函理论（DFT）的振动光谱分析和量子化学计算已经在有机晶体 L-脯氨酸苦味酸盐（LPP）上进行。使用 B3LYP 方法研究了 LPP 的平衡几何形状、各种键合特征和谐振动波数。计算的分子几何形状与实验数据进行了比较。借助 VEDA 4 程序对振动光谱进行了详细解释。通过自然键轨道分析揭示了确认化合物生物活性的各种分子内相互作用。与氢键相关的 Mulliken 原子电荷分布和自然杂化轨道的弯曲也反映了分子内氢键的存在，从而增强了生物活性。分析 HOMO 和 LUMO 的电子密度可以了解离域和低能隙值，这表明分子中的电子传输和生物活性。振动分析表明，L-脯氨酸和苦味酸离子之间存在强烈的 O-H···O 和 N-H···O 相互作用，为供体和受体基团之间的电荷转移相互作用提供了证据，这是其生物活性的原因。
