Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu, India.
J Mol Model. 2013 Aug;19(8):3411-25. doi: 10.1007/s00894-013-1866-0. Epub 2013 May 18.
Twenty cocaine-water complexes were studied using density functional theory (DFT) B3LYP/6-311++G** level to understand their geometries, energies, vibrational frequencies, charge transfer and topological parameters. Among the 20 complexes, 12 are neutral and eight are protonated in the cocaine-water complexes. Based on the interaction energy, the protonated complexes are more stable than the neutral complexes. In both complexes, the most stable structure involves the hydrogen bond with water at nitrogen atom in the tropane ring and C=O groups in methyl ester. Carbonyl groups in benzoyl and methyl ester is the most reactive site in both forms and it is responsible for the stability order. The calculated topological results show that the interactions involved in the hydrogen bond are electrostatic dominant. Natural bond orbital (NBO) analysis confirms the presence of hydrogen bond and it supports the stability order. Atoms in molecules (AIM) and NBO analysis confirms the C-H···O hydrogen bonds formed between the cocaine-water complexes are blue shifted in nature.
使用密度泛函理论 (DFT) B3LYP/6-311++G** 水平研究了 20 个可卡因-水配合物，以了解它们的几何形状、能量、振动频率、电荷转移和拓扑参数。在 20 个配合物中，有 12 个是中性的，有 8 个是可卡因-水配合物中的质子化的。基于相互作用能，质子化的配合物比中性配合物更稳定。在这两种配合物中，最稳定的结构涉及与氮原子在托烷环上的水和甲酯中的 C=O 基团形成氢键。苯甲酰基和甲酯中的羰基基团是两种形式中最具反应性的部位，这也是稳定性顺序的原因。计算得到的拓扑结果表明，氢键涉及的相互作用是静电主导的。自然键轨道（NBO）分析证实了氢键的存在，并支持了稳定性顺序。分子中的原子（AIM）和 NBO 分析证实，在可卡因-水配合物之间形成的 C-H···O 氢键具有蓝移性质。
