N-甲硝胺二聚体分子间相互作用的理论研究

用ab initio方法，在HF／6－31G水平下求得N－甲硝胺二聚体势能面上3种优化构型，经MP4和MP2校正电子相关能及校正基组叠加误差（BSSE），求得分子间最大相互作用能为－18．81kJ.mol^-1，甲基内旋转对相互作用能影响较大，在标准状态下，由单体形成最稳定二聚体的自由能变化为10．02kJ.mol^-1，同时还讨论了温度对过程的影响。     

叠氮化氢二聚体的分子间相互作用

通过ａｂ ｉｎｉｔｉｏＨＦ／６－３１Ｇ＊计算求得叠氮化氢二聚体（ＨＮ３）２势能面上四种优化结构型,经ＭＰ４ＳＤＴＱ电子相关校正和基组叠加误差２校正求得这些构型下的分子间相互作用能。结果表明,在四种优化构型中Ｎ３Ｈ．．．ＮＨＮ２最稳定,其分子间相互作用能为－１６．０７ＫＪ．ｍｏｌ＾－１。     

PH~3...H~2O体系分子间相互作用的从头计算MO研究

在MP2/6-311++G(3d,3p)水平,对PH~3...H~2O体系可能存在的氢键复合物进行了全自由度能量梯度优化,发现PH~3...H~2O体系存在三个能量极小结构A,B和C。其中结构A和B以H~2O作为质子授体,结构C以PH~3作为质子授体,结构A较结构B和C分别稳定6.52kJ/mol和8.18kJ/mol。结构A具有C~s对称性,其结构中P原子和O原子间距离为354.78nm,键角OHP为171.35ⅲ,属于接近于直线的传统型氢键结构。进一步在高级电子相关校正的MP4SDTQ下,用6-311++G(3df,3pd)基加上键函数{3s3p2d1f},通过BSSE校正,精确计算了结构A的结合能为-10.84kJ/mol。     

叠氮乙烷二聚体分子间相互作用的理论研究

Energetic materials are aggregative and mixed systems. The intermolecular interactions play significantroles in the physical,chemical and explosive property. The study on intermolecular interactions of energetic materials has attracted wide attention. The organic azides are an important category of energetic materials and widely used in many fields. Ethyl azide is the simple model having the explosive property for the organic azides energetic compound. Ethyl azide monomer（Ⅰ）and all its possible stable clusters（Ⅱ,Ⅲ and Ⅳ）are fully optimized by ab initio method at the HF/6-311++G** level. Vibrational frequencies calculated to ascertain each structure are characterized to be the stable structure（no imaginary frequencies）. The proportions of correlated interaction energies to their total interaction energies ΔE（MP2）are 65.14%,63.76% and 65.62% for Ⅱ,Ⅲ and Ⅳ respectively. In addition,the basis set superposition error（BSSE）correction energies are 7.82,7.61 and 4.40 kJ/mol for Ⅱ,Ⅲ and Ⅳ respectively. The zero point energy （ZPE） corrections for the interaction energies are much less than those of MP2 electron correlation and BSSE correction energies. After MP2 electron correlation correction,BSSE and ZPE correction,the greatest corrected intermolecular interaction of the dimers is -10.45 kJ/mol. The charge redistribution mainly occurs on the adjacent N?H atoms between submolecules. The charge transfer between two subsystems is very small. Natural bond orbital（NBO）analysis is performed to reveal the origin of the interaction. Based on the statistical thermodynamic method,the standard thermodynamic functions,heat capacities（C0p）,entropies（S0m）and enthalpies（H0m）and the changes of thermodynamic properties from the monomer to dimer with the temperatures ranging from 200. 00 K to 800. 00 K have been obtained.     

超分子体系弱相互作用的量子化学计算

介绍了近年来超分子体系弱相互作用的最子化学计算方法，重点讨论了严格的从头计算方法及其各种校正技术，介绍了当前进展及其所取得的成果。     

分子间相互作用的量子化学研究方法

分子间相互作用是一类十分重要的作用, 这类作用的实验和理论研究越来越受到化学家、生物学家、材料科学家等的重视。本文综述了这种相互作用的量子化学研究现状和特点, 主要集中于常见的3 种量子化学方法。并对该领域的研究前景作了展望。     

含两个酰胺基团的卟啉二聚体分子间氢键引起的发光光谱红移

通过5-(4-甲酸基苯基)-10,15,20-三(4-十二烷氧基苯基)卟啉(HAc TPP)与乙二胺,丙二胺和丁二胺反应,制备了一类含2个酰胺基团的卟啉二聚体C2(Am TPP)2、C3(Am TPP)2和C4(Am TPP)2以及相应的配合物Pt2C2(Am TPP)2、Pt2C3(Am TPP)2和Pt2C4(Am TPP)2。采用1H NMR、13C NMR、质谱、元素分析、循环伏安、紫外-可见吸收光谱和荧光发射光谱等对二聚体的化学结构、热稳定性、电化学和光物理性质进行了表征。实验发现,二聚体和相应的铂配合物的光致发光(PL)光谱性质与溶液的浓度有关,在10-7mol·L-1THF稀溶液中,二聚体与单羧基卟啉的PL光谱基本一致。当浓度增加到10-3 mol·L-1 THF溶液时,二聚体的光致发光光谱最大值从657 nm红移到675 nm,比单羧基卟啉红移了18 nm。当与金属铂配位后,这种发射光谱随浓度增加而变化的特性更加明显。二聚体配合物在10-7 mol·L-1 THF稀溶液中PL光谱就产生了红移现象,最大发射峰λmax为673 nm,比单羧基卟啉红移16 nm。在高浓度10-4 mol·L-1 THF溶液和升华薄膜中的PL最大发射峰进一步红移到727 nm的近红外区。进一步,为了证实二聚体配合物分子间的π-π和Pt-Pt相互作用,我们以配合物Pt2C3(Am TPP)2为例,对二聚体配合物固体在常温和低温77K的PL光谱进行了测试,发现固体配合物表现出与温度相关的PL性质。当温度降到77 K时,配合物的最大发射峰从658 nm红移到674 nm,红移了16 nm。实验表明,卟啉二聚体和相应的配合物的红移现象与二聚体的分子结构直接相关,卟啉二聚体中的两个酰胺基团能够产生较强的分子间氢键,导致二聚体分子之间产生一定程度的π-π和Pt-Pt相互作用,使得二聚体PL光谱产生红移。     

新型1,8-萘酰亚胺类化合物与DNA相互作用的研究

用荧光光谱、紫外光谱、粘度法对两种新型1,8-萘酰亚胺类化合物N-羟乙基-3-硝基-4-溴-1,8-萘酰亚胺(B)和N-羟乙基-4-羟乙基-3-硝基-1,8-萘酰亚胺(N)与DNA的相互作用进行了研究,考察和比较了它们与DNA的作用模式和强度,求出了两种化合物的嵌入常数。结果表明,化合物N和B主要以插入方式与DNA作用,且化合物N与DNA的作用强于化合物B。     

含两个酰胺基团的卟啉二聚体分子间氢键引起的发光光谱红移

通过5-（4-甲酸基苯基）-10,15,20-三（4-十二烷氧基苯基）卟啉（HAcTPP）与乙二胺,丙二胺和丁二胺反应,制备了一类含2个酰胺基团的卟啉二聚体C₂（AmTPP）₂、C₃（AmTPP）₂和C₄（AmTPP）₂以及相应的配合物Pt2C₂（AmTPP）₂、Pt2C₃（AmTPP）₂和Pt2C₄（AmTPP）₂。采用¹H NMR、¹³C NMR、质谱、元素分析、循环伏安、紫外-可见吸收光谱和荧光发射光谱等对二聚体的化学结构、热稳定性、电化学和光物理性质进行了表征。实验发现,二聚体和相应的铂配合物的光致发光（PL）光谱性质与溶液的浓度有关,在10^-7 mol·L^-1 THF稀溶液中,二聚体与单羧基卟啉的PL光谱基本一致。当浓度增加到10^-3 mol·L^-1 THF溶液时,二聚体的光致发光光谱最大值从657 nm红移到675 nm,比单羧基卟啉红移了18 nm。当与金属铂配位后,这种发射光谱随浓度增加而变化的特性更加明显。二聚体配合物在10^-7 mol·L^-1 THF稀溶液中PL光谱就产生了红移现象,最大发射峰λ_max为673 nm,比单羧基卟啉红移16 nm。在高浓度10^-4 mol·L^-1 THF溶液和升华薄膜中的PL最大发射峰进一步红移到727 nm的近红外区。进一步,为了证实二聚体配合物分子间的π-π和Pt-Pt相互作用,我们以配合物Pt2C₃（AmTPP）₂为例,对二聚体配合物固体在常温和低温77 K的PL光谱进行了测试,发现固体配合物表现出与温度相关的PL性质。当温度降到77 K时,配合物的最大发射峰从658 nm红移到674 nm,红移了16 nm。实验表明,卟啉二聚体和相应的配合物的红移现象与二聚体的分子结构直接相关,卟啉二聚体中的两个酰胺基团能够产生较强的分子间氢键,导致二聚体分子之间产生一定程度的π-π和Pt-Pt相互作用,使得二聚体PL光谱产生红移。     

硝酸乙酯分子间相互作用的ab initio研究

在abinitio-HF/6-31G水平上求得硝酸乙酯二聚体势能面上的四种优化构型和电子结构。经MP2电子相关校正和基组叠加误差(BSSE)以及零点能(ZPE)校正，求得二聚体的最大结合能为11.46kJ.mol^-^1，还进行HF/6-311G和HF/6-311++G水平的总能量比较计算，发现6-31G基组对计算结合能比较适合，二子体系间的电荷转移很少，对优化构型进行振动分析，并基于统计热力学求得从单体形成二聚体的热力学性质变化。     

Ab initio Studies on Intermolecular Interaction of Formamide and Hydroxyacetonitrile Dimers

The structures, the binding energies and the thermodynamic properties of formamide and hydroxyacetonitrile(HAN) dimers have been studied by means of the self-consistent ab initio Hartree-Fock and the second-order Mφller-Plesset correlation energy correction methods. The counterpoise procedure was used to check the basis set superposition error(BSSE) of the binding energies. There exist cyclic structures in a formamide dimer(Ⅰ), a HAN dimer(Ⅱ) and their heterodimer(Ⅲ). The corrected binding energies for dimers Ⅰ, Ⅱ and Ⅲ are respectively -45.53, -45.83 and -43.89 kJ/mol at the MP2/aug-cc-p VDZ//HF/aug-cc-p VDZ level. The change of the Gibbs free energies(ΔG) in the process of Ⅰ Ⅱ→2Ⅲ was predicted to be -2.74 kJ/mol at 298.15 K. Dimer Ⅲ can be spontaneously produced in the mixture of formamide and HAN, which is in agreement with the experimental fact that most cyanohydrins are capable of interacting with dipeptide cyclo-His-Phe(CHP).     

Theoretical Study on the Intermolecular Interactions of Tetrazole Dimers

1 INTRODUCTION Tetrazole and its derivatives are widely applied in the fields of agriculture, biology, chemistry, phar- macology and photographic technology, and they play significant roles in the science and technology as well as national defence[1]. In the past, the res- earches were focused on the molecular geometries, electronic structures, IR, thermodynamic properties, tautomerization, pyrogenation and sensitivity of tetrazole compounds[1～5]. However, study of tetra- zole dimers ha…     

Theoretical Study on Intermolecular Interactions and Thermodynamic Properties of Nitroamine Dimers

Ab initio self-consistent field(SCF) and Mφller-Plesset correlation correction methods employing 6-31G^** basis set have been applied to the optimizations of nitroamine dimers.The binding energies have been corrected for the basis set superposition error (BSSE) and the zero-point energy.Theree optimized dimers have been obtained.The BSSE corrected binding energy of the most stable dimer is predicted to be -31.85kJ/mol at the MP4/6-31G^**//MP2/6-31G^** level.The energy barriers of the Walden conversion for -NH2 group are 19.7kJ/mol and 18.3kJ/mol for monomer and the most stable dimer,respectively.The molecular interaction makes the internal rotation around N1-N2 even more difficult.The thermodynamic properties of nitroamine and its dimers at different temperatures have been calculated on the basis of vibrational analyses.The change of the Gibbs free energy for the aggregation from monomer to the most stable dimer at standard pressure and 298.2 K is predicted to be 14.05kJ/mol.     

Ab initio Study on the Intermolecular Interaction and Thermodynamic Properties of Methyl Nitrate Dimer

Three stable dimers of methyl nitrate have been obtained and their geometries have been fully optimized at the HF/6‐31G,. level. Binding energies have been calculated with correction for the basis set superposition error (BSSE) and zero point energy (ZPE). The cyclic overlap‐type structure, the binding energy of which is 11.97 kJ/mol at the MP4SDTQ/6‐31G. / HF/6‐31G. level, is the most stable. No intermolecular hydrogen bond was found, and the charge transfer between two subsystems is minute. The thermodynamic properties of methyl nitrate and its dimers have been calculated based on the vibrational analysis and statistical thermodynamics.     

Intermolecular Interaction of HMX： an Application of ONIOM Methodology

IntroductionExtensive studies on intermolecular interac-tions have been made in the past decades due totheir importance in a wide range of physical,chem-ical and biological fields.Researches on the weakintermolecular interactions began with hydrogenbonds.Scheiner summarized the ab initio investiga-tions on hydrogen bonding in detail[1] .With the abinitio method supermolecular structures and bind-ing energies can be predicted notonly for H- bondedsystems but also for other systems[2 _ 5] when …     

CH3F分子间相互作用的ab initio研究

在MP2/6-311+ +G(3d,3p)电子相关校正水平上,对CH₃F二聚体可能存在的几何构型进行全自由度能量梯度优化和频率验证,发现3种势能面上有极小点的构型.进一步在高级电子相关校正的MP4S-DTQ、CCSD(T)/6-311+ +G(3df,3pd)方法水平上,对其中总能量最小的构型进行精确计算,得到二聚体的结合能为-9.707kJ/mol.研究结果支持了由光谱实验结果推测的构型,解释了CH₃F二聚体的谐振频率的多样性.     

Packing Structures of Thiophene Dimers and Their Effects on Excitation Energies of Thiophene Dimers

IntroductionPi(π) conjugated polymers have received exten-sive experimental and theoretical attention because oftheir fascinating electronic and optical properties[1—3].Recently, many new experiment results[4—6]have re-vealed that the inter-chain inter…     

Quantum Chemical Exploration of Intermolecular Reactions of Acetylene

Quantum chemical explorations of potential energy surfaces showed that acetylene produces various products starting from molecular arrays in short distances of 1.3–2.5 Å. Arrays of (C₂H₂)₂ gave cyclobutadiene, tetrahedrane, and acetylene dimers. Arrays of (C₂H₂)₃ gave benzene, prismane, benzvalene, Dewar benzene, and acetylene trimers. Arrays of (C₂H₂)₄ gave cubane, cyclooctatetranene, and acetylene tetramers. Different forms of initial arrays yielded different sets of products; a parallel array of two monomers gave cyclobutadiene, whereas a cross array gave tetrahedrane. Initial molecular arrays with unusually close contacts were estimated to require local forces of 1–9 × 10⁻⁸ N. © 2019 Wiley Periodicals, Inc.