Chopra Neha, Chopra Geetanjali, Kaur Damanjit
Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, India.
ACS Omega. 2019 May 3;4(5):8112-8121. doi: 10.1021/acsomega.8b03496. eCollection 2019 May 31.
The second-order Møller-Plesset perturbation theory (MP2) and density functional theory with dispersion function calculations have been applied to investigate the hydrogen-bonding interaction between azines and water. The study suggests that the ability of nitrogen present in azine to act as a hydrogen-bond acceptor decreases in the order of pyridine () > diazine () > triazine () > tetrazine () > pentazine () > hexazine (). Natural bond orbital (NBO) analysis, atoms in molecules, symmetry-adapted perturbation theory (SAPT), and molecular electrostatic potential studies reflect the factors important for hydrogen-bond strength as well as for the structural, electronic, and vibrational changes occurring during complexation. NBO analysis reflects that upon gradual addition of nitrogen atoms, hyperconjugation leads to an increase in the population of antibonding O-H bond, thus causing elongation and weakening of O-H bond in complexes incorporating N···H-O interaction, whereas rehybridization leads to an increase in the s character of the carbon hybrid orbital in C-H bond, thus causing contraction and shortening of C-H bond in complexes having C-H···O interactions. From the topological analysis, an excellent linear correlation is found to exist between stabilization energy (Δ ), electron density (ρ), and its Laplacian (∇ρ) at the bond critical points.
二阶莫勒-普列斯特定则微扰理论（MP2）以及带有色散函数计算的密度泛函理论已被用于研究吖嗪与水之间的氢键相互作用。研究表明，吖嗪中氮作为氢键受体的能力按吡啶（）> 二嗪（）> 三嗪（）> 四嗪（）> 五嗪（）> 六嗪（）的顺序降低。自然键轨道（NBO）分析、分子中的原子、对称适配微扰理论（SAPT）以及分子静电势研究反映了对于氢键强度以及络合过程中发生的结构、电子和振动变化而言重要的因素。NBO分析表明，随着氮原子的逐渐添加，超共轭导致反键O-H键的占据数增加，从而在包含N···H-O相互作用的络合物中导致O-H键伸长并减弱，而重新杂化导致C-H键中碳杂化轨道的s特征增加，从而在具有C-H···O相互作用的络合物中导致C-H键收缩并缩短。从拓扑分析中发现，在键临界点处的稳定化能（Δ ）、电子密度（ρ）及其拉普拉斯量（∇ρ）之间存在极好的线性相关性。
