HArF和HNO二聚体相互作用氢键的理论研究

用二阶微扰理论结合6-311+G**、6-311++G**和6-311++G(2d,2p)基组对氢键相互作用二聚体HNO···HArF进行研究．在MP2/6-311+G**、MP2/6-311++G**和MP2/6-311++G(2d,2p)水平上，利用标准方法和均衡校正方法对二聚体进行了几何优化、振动频率和相互作用能的计算．对于相互作用能采用G2MP2方法计算．计算结果表明存在两种稳定的二聚体HNO···HArF结构，在这两种结构中，Dimer I(H···F)比Dimer II(H···O)更加稳定．通过振动频率的计算表明，在Dimer I(H···F)中存在N-H···F蓝移氢键，在DimerII(H···O)中存在Ar-H···O红移氢键，并对蓝移氢键加以确认．利用电子密度拓扑学分析和自然键轨道分析对于氢键红移和蓝移进行了合理解释．     

HOX(X=F,Cl)二聚体红移氢键的理论研究

用理论方法研究了二聚体HOX(X=F,Cl)分子间氢键,在B3LYP/6-31+G(d,p)、 B3LYP/6-311++G(d,p)、MP2/6-31+G(d,p)和MP2/6-311++G(d,p)水平上,利用标准方法和均衡校正方法对二聚体进行了几何优化、振动频率和相互作用能的计算。同时,利用电子密度拓扑分析和自然键轨道分析对红移氢键的本质进行了分析。研究表明：分子间O—H…O和O—H…X(X=F,Cl)氢键的形成使二聚体中O—H键伸长,伸缩振动频率减小,形成红移氢键。NBO分析表明,电荷转移效应占优势,因此形成O—H…O和O—H…X(F,Cl)红移氢键。     

1,3,5-三氮杂苯－水簇氢键结构性质

在B3LYP/6-31 G**和MP2/6-31 G**水平上对1,3,5-三氮杂苯-(H2O)n(n=2,3)复合物的基态氢键结构进行几何优化和性质计算,结果表明复合物之间存在较强的氢键相互作用,所有稳定复合物结构中形成一个N…H-O氢键并终止于弱O…H-C氢键的氢键水链构型最稳定.氢键的形成是水分子中H-O键振动频率减小(红移).NBO分析表明,最稳定的1:2和1:3复合物发生分子问电荷转移总量分另q为0.02501 e和0.02777 e.     

Cu+与N-[2-羟基-1(S)-甲基]-N-甲基甘氨酸间的C-H…Cu(Ⅰ)抓氢键

采用密度泛函B3LYP(Becke, three-parameter, Lee-Yang-Parr)/6-311G**理论水平研究了Cu+和Cu2+离子与N-[2-羟基-1(S)-甲基]-N-甲基甘氨酸根负离子配体（PT）形成的配合物的结构,重点讨论了配合物中的C-H Cu抓氢键结构. 计算表明, 当单个配体与Cu+结合时,配合物PT•••Cu(Ⅰ)结构中有C-H Cu抓氢键形成,C-H键伸缩振动频率显著红移,键长显著增大而被活化, 配体为三齿配体;当两个配体与Cu2+结合时,配合物PT•••Cu(Ⅱ)不存在C-H Cu抓氢键结构,配体为双齿配体. NBO及AIM理论分析均表明C-H Cu抓氢键属于一种较强的基团间相互作用,在强度和电子行为上与氢键弱相互作用有本质不同.     

气相中HOCl和O3分子间氯键和氢键的结构和性质

在DFT-B3LYP/6-311 G**水平上分别求得O3…ClOH氯键复合物和O3…HOCl氢键复合物势能面上的稳定构型.频率分析表明,与单体HOCl相比,分别在两种复合物中,Cl4-O5和H6-O5键伸缩振动频率发生红移,红移值分别为5.70和76.44cm-1.经MP2/6-311 G**水平计算的含BSSE和零点振动能校正的气相中相互作用能分别为-2.102和-4.920 kJ·mol-1.NBO分析表明,在O3…ClOH氯键复合物中,引起Cl4-05键变长的因素包括2种电荷转移:(1)LP(O1)1→σ*(C14-05);(2)LP(O1)2→σ*(Cl4-O5),其中LP(O1)2→σ*((Cl4-O5)转移占主要作用,总的结果是使σ*(Cl10-O11)的自然布居数增加了14.44 me;在O3…HOCl氢键复合物中也存在类似的电荷转移,结果使σ*(H6-O5)的自然布居数增加了18.09 me.NRT理论进行键序分析表明,在氯键复合物和氢键复合物中,Cl4-O5和H6-O5键的键序都减小,与红外光谱频率计算分析和NBO分析的结论一致.AIM理论分析表明,分别在两种复合物中,O1…Cl4间和O1…H6间都存在键鞍点,而且O1…Cl4和O1…H6的P(r)都较小,分别为0.0111和0.0152 a.u.,说明复合物中的氯键和氢键相互作用较弱.另外,O1…Cl4氯键和O1…H6氢键的Laplacian量(△)ρP(r)分别为0.0479和0.0641 a.u.,都是较小的正值,说明这两种相互作用都以静电作用为主.     

硝酸羟胺-(H_2O)_n复合物氢键相互作用的密度泛函研究

为研究硝酸羟胺-(H_2O)_n复合物的氢键作用,采用密度泛函B3LYP方法在6-311++G(d, p)基组水平上对硝酸羟胺-(H_2O)_n复合物的结构进行优化,采用MP2/6-311++G(d, p)方法,经基组叠加误差和零点能校正计算得到复合物的相互作用能.利用自然键轨道分析方法研究复合物氢键作用的本质,并对复合物中水分子的振动光谱进行分析.计算结果表明,硝酸羟胺-(H_2O)_n复合物存在着6个硝酸羟胺-H_2O稳定构型和8个硝酸羟胺-(H_2O)_2稳定构型,且最稳定构型的相互作用能分别为52.821 kJ·mol~(-1)和73.349 kJ·mol~(-1).在硝酸羟胺-(H_2O)_n复合物中,水中H-O伸缩振动频率明显红移,且红移增大的程度与复合物稳定化能的变化趋势基本一致.     

1,2,3-三氮杂苯-水复合物氢键相互作用

用密度泛函理论在B3LYP/6-31 G**水平上对1,2,3-三氮杂苯和水形成1:1、1:2和1:3复合物的基态氡键结构进行几何优化和性质计算．计算结果表明,复合物之间存在较强的氢键作用．所有稳定复合物结构中形成一个N…H-O氢键并终止于O…H-C氢键的氢键水链构型最稳定．氢键的形成是水分子中H-O键振动频率减小(红移)．NBO分析表明,最稳定的1:1、1:2和1:3复合物发生分子间电荷转移总量分别为0．0222e、0．0261e和0．0273e．同时,用含时密度泛函理论方法在TD-B3LYP/6-31 G**水平计算了1,2,3-三氮杂苯单体及其氢键复合物的第一1(n,π*)激发态的垂直激发能．     

腺嘌呤-水分子团簇的理论研究

利用密度泛函理论在B3LYP/6-311++G(d , p)基组水平上对C5H5N5·(H2O)m (m=1~3)进行了优化与振动频率计算,得到了团簇的六种稳定结构. 应用AIM程序计算了三种最稳定结构的氢键临界点的拓扑参数,结果表明,O—H…N氢键的形成使得O—H之间电子密度减小,伸缩振动频率减小,产生了红移;N—H…O氢键的形成使得N—H之间的电子密度减小,键的强度变弱,伸缩振动频率变小,发生了红移. 利用veda4软件对团簇C5H5N5·(H2O)m (m=0~3)的红外光谱的振动频率进行模式指认,并对部分振动频率进行了比较.     

腺嘌呤-水分子团簇结构与振动频率的理论研究

利用密度泛函理论在B3LYP/6-311++G(d,p)基组水平上对C_5H_5N_5·(H_2O)m(m=1~3)进行了优化与振动频率计算,得到了团簇的六种稳定结构.应用AIM程序计算了三种最稳定结构的氢键临界点的拓扑参数,结果表明,O—H…N氢键的形成使得O—H之间电子密度减小,伸缩振动频率减小,产生了红移;N—H…O氢键的形成使得N—H之间的电子密度减小,键的强度变弱,伸缩振动频率变小,发生了红移.利用veda4软件对团簇C_5H_5N_5·(H_2O)m(m=0~3)的红外光谱的振动频率进行模式指认,并对部分振动频率进行了比较.     

紫草素与胞嘧啶相互作用的理论研究

采用密度泛函理论的M06方法在6-311++G**基组水平下对紫草素-胞嘧啶复合物进行了结构优化,得到了14个稳定的紫草素-胞嘧啶复合物。我们还应用了分子中的原子(AIM)理论和自然键轨道(NBO)理论对这14个复合物中的氢键的性质和特征进行了分析。通过基组重叠误差(BSSE)校正后的相互作用能、成键临界点电荷密度、二阶稳定化能的计算和分析,发现复合物1的结构是最稳定的。     

乙二醇分子间氢键结构与溶剂效应

采用密度泛函理论在B3LYP/6-311++G~(**)水平上研究乙二醇在气相中分别与乙腈、丙酮、四氢呋喃、水、乙二醇形成氢键二聚体的结构性质,根据PCM(polarized continuum model)极化统一场模型讨论氢键溶剂效应.结果表明,五种氢键二聚体分子中的氢键属于红移氢键,溶剂使氢键二聚体分子的偶极矩变大,并对OH振动频率的影响不大.     

乙二醇分子间氢键结构与溶剂效应

采用密度泛函理论在B3LYP/6-311++G** (范德华校正)水平上研究乙二醇在气相中分别与乙腈、丙酮、四氢呋喃、水、乙二醇形成氢键二聚体的结构性质,根据PCM 极化统一场模型讨论氢键溶剂效应。结果表明,五种氢键二聚体分子中的氢键属于红移氢键,溶剂使氢键二聚体分子的偶极矩变大,并对OH振动频率的影响不大。     

The mutual relationship between H-bonding and π-stacking interactions: the estimation of individual binding energies in the phenylalanine:G ··· C ternary complex

The mutual relationship between stacked interaction and the individual hydrogen bonds in the phenylalanine:guanine?···?cytosine (Ph:G-C) and phenylalanine:cytosine?···?guanine (Ph:C-G) complexes have been studied at the MPWB1K/6-311++G** and M05-2X/cc-pVDZ levels of theory. The interplay of π-stacking and H-bonding results in the weakening of both interactions. The effect of π-stacking on the geometries and individual hydrogen bond (HB) energies of guanine–cytosine (G-C) base pair have been investigated using electron densities calculated by the atoms in molecules (AIM) method at the hydrogen bond critical points (BCP). The results of AIM analysis are in good agreement with the calculated individual hydrogen bond energies. The π-stacking interactions strengths the HB1 and weakens HB2 and HB3 in the Ph:G-C complexes, while the opposite is true in the Ph:C-G complex. With the increase in the distance between phenylalanine ring and the groups involved in H-bond interactions the change in the H-bond energy increases and the changes in the individual H-bond and π-stacking energies decrease in the ternary complexes.     

First-principle study of the hydrogen bonds in a thin film of phthalocyanine molecules

The nature and the strength of intermolecular contacts involved in molecular self-assemblies on a substrate strongly depend on the surrounding functional atoms. Recently, it has been shown that deposition of chlorine-zinc-phthalocyanine (ZnPcCl₈) molecules on Ag(1 1 1) leads to a compact arrangement governed by the activation of a Cl ? H-C bond network. A detailed theoretical study of these contacts based on first-principle density functional calculations and topological analysis of the electron density is reported in this paper. This study reveals that the mechanism of the Cl ? H-C contacts is similar to that of weak hydrogen bonds.     

DFT study on abstraction reaction mechanism of oh radical with 2‐methoxyphenol

Reaction mechanism of 2‐methoxyphenol (2MP) (guaiacol) with OH radical has been performed using density functional theory methods BH&HLYP and MPW1K method with 6‐311++G(d,p) basis set. Single‐point energy calculations were done using CCSD(T)/6‐311++G(d,p). The theoretical results reveal that the hydrogen abstraction from methoxy group is found to be the dominant reaction channel with an energy barrier of 9.31 kcal/mol. Also, time‐dependent density functional theory calculations have been performed using BH&HLYP/6‐311++G(d,p) level of theory, and the results reveal that the reactions occur in ground state than the excited state. The results of reaction force profile indicate that structural rearrangements are most influential with high percentage than the relaxation process. The calculated theoretical rate constants (12.19 × 10^?11 cm³ molecule^?1 s^?1) are in good agreement with the experimental rate constant. The atmospheric lifetime of 2‐methoxyphenol with respect to OH radicals is 2.27 hours, which implies that OH radical plays an important role in the degradation of 2MP. The Wiberg bond index of the abstraction reaction reveals that the bond order is concerted, partially synchronic. The reactant‐like transition state satisfies Hammond postulate, which eventually results in an exothermic reaction, and the product‐like transition state reveals in endothermic nature.     

儿茶素与脱氧腺苷相互作用的理论研究

本文采用密度泛函理论的M05方法,在6-311+G**基组水平上对建模的儿茶素-脱氧腺苷复合物进行几何结构的优化,得到了13个稳定的儿茶素-脱氧腺苷复合物.应用了自然键轨道(NBO)理论和分子中的原子理论(AIM)进行研究,氢键临界点电荷密度,拉普拉斯值,糖基扭转角!,假扭转角P等数据进行辅助研究,对这13种复合物中氢键的特征与性质进行了分析,还考虑了溶剂化效应对儿茶素与脱氧腺苷相互作用的影响.计算结果表明氢键对于复合物的稳定性起着非常重要的作用,而氢键的类型以及键级的大小共同影响着复合物的稳定性.所有的复合物进行基组重叠误差(BSSE)校正,相互作用能主要来自氢键贡献.通过计算结果分析比较,进而在理论上为儿茶素类药物的设计、修饰﹑合成和筛选提供有价值的信息.     

Dihydrogen bond in C2H4− n Cl n ··· NaH (n = 0, 1, 2, 3) complexes: ab initio,AIM and NBO studies

The dihydrogen-bonded complexes of ethylene and its chlorine derivatives with sodium hydride have been systematically investigated at the MP2/6-311++G(d,p) level. The studied complexes are divided into three groups (including Linear, Five- and Six-membered cyclic structures) based on the optimized structures. The structural, energetic and topological parameters are presented and analysed in terms of their possible correlation with the interaction energies and the intermolecular H?···?H distances. The nature of the electrostatic interaction in this type of dihydrogen bond has also been unveiled by means of atoms in molecules (AIM) and natural bond orbital (NBO) analysis. The effect of ring structure on the dihydrogen bonding systems has been considered by comparing with the corresponding linear structure. NBO analysis suggests that the electron density transfer (EDT) in cyclic structures have dual-channel character.