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1.
以甲胺(MA)和二甲胺(DMA)为结构导向剂,在200℃加热摩尔组成为n(Al2O3)∶n(P2O5)∶n(R)∶n(H2O)=1∶1∶1∶277(R=MA,DMA)的混合物,分别得到了高结晶度的三维阴离子开放骨架磷酸铝Al PO4-53和Al PO4-21.质子化的甲胺和二甲胺分别位于Al PO4-53和Al PO4-21的骨架中以平衡骨架的负电荷.利用X射线粉末衍射分析、元素分析和液相酸碱度测量等表征手段,研究了2个合成体系的晶化过程以及晶化过程中液相的Al,P浓度和p H值随时间的演化.理论计算结果表明,质子化甲胺和二甲胺的N原子上的电荷分别为-0.263和-0.558 e(Mulliken),形式电荷密度分别为22.3和16.0 e/nm3,Al PO4-53和Al PO4-21的骨架电荷密度分别为-3.3和-3.1 e/nm3.结果表明,改变N原子的环境会影响其上的电荷量,从而改变有机胺的结构导向效应,有机胺的形式电荷密度和无机骨架电荷密度之间存在着匹配关系.  相似文献   

2.
报道对氨 (NH3,母体 )、甲胺 (CH3NH2 )、二甲胺 [(CH3) 2 NH]、三甲胺 [(CH3) 3N]与三氯甲烷 (CHCl3)形成的系列复合物的理论研究结果 .把复合物看作一个超分子 ,在B3LYP/ 6- 3 11G(d ,p)的水平上进行密度泛函法计算 ,并运用完全均衡校正法进行基组超位误差校正 (BSSE) .探讨该系列复合物的电子结构与相关性质 ,如稳定性、电荷转移及主要几何参数的变化规律等 .结果表明 ,形成复合物的稳定性次序为NH3-CHCl3(Ⅰ ) >CH3NH2 -CHCl3(Ⅱ ) >(CH3) 2 NH -CHCl3(Ⅲ ) >(CH3) 3N -CHCl3(Ⅳ ) .形成复合物的过程包含着电荷转移 .该系列复合物的稳定性与电荷转移量、前线轨道能量差ΔεL -H及广义H键距离有良好的线性关系 ,与结合点的电荷布居也有密切的关系 .复合物的稳定性是分子间共价作用和静电作用两方面因素综合的结果 .计算结果能较好地解释有关的实验现象和规律  相似文献   

3.
采用色谱法与热重(TG)法,测量了正己烷、甲苯和乙酸乙酯在活性炭、5A、NaY、13X、ZSM-5 (SiO_2/Al_2O_3=27、300)、Hβ以及M CM-41等吸附剂上不同温度下的吸脱附行为,并基于反相气相色谱法测得的数据,计算了其吸附热力学参数ΔH、ΔS和ΔG,分析了上述VOCs分子与吸附剂之间的作用机制,并借助FT-IR验证了吸附质在分子筛表面的吸附机制。结果表明,上述吸附过程存在物理吸附和化学吸附两种方式,其中,物理吸附的作用力大小与吸附剂的孔径分布和分子直径相关,而化学吸附的作用力大小依赖于分子筛硅铝比和Ca~(2+)、Na~+、H~+等阳离子及吸附质分子的偶极矩,且强的化学吸附使得部分吸附质分子的脱附温度高于200℃。  相似文献   

4.
报道对氨(NH3,母体)、甲胺(CH3NH2)、二甲胺[(CH3)2NH]、三甲胺[(CH3)3N]与三氯甲烷(CHCL3)形成的系列复合物的理论研究结果.把复合物看作一个超分子,在B3LYP/6-311G(d,p)的水平上进行密度泛函法计算,并运用完全均衡校正法进行基组超位误差校正(BSSE).探讨该系列复合物的电子结构与相关性质,如稳定性、电荷转移及主要几何参数的变化规律等.结果表明,形成复合物的稳定性次序为NH3-CHCl3(Ⅰ)>CH3NH2-CHCL3(Ⅱ)>(CH3)2NH-CHCl3(Ⅲ)>(CH3)3N-CHCl3(Ⅳ).形成复合物的过程包含着电荷转移.该系列复合物的稳定性与电荷转移量、前线轨道能量差ΔεL-H及广义H键距离有良好的线性关系,与结合点的电荷布居也有密切的关系.复合物的稳定性是分子间共价作用和静电作用两方面因素综合的结果.计算结果能较好地解释有关的实验现象和规律.  相似文献   

5.
采用吡啶饱和中毒、NH3-TPD、静态吸附、IR、XRD和分子探针反应等方法,研究了用于甲醇胺化反应的改性丝光沸石催化剂性质.结果发现,丝光沸石水汽处理脱铝后的孔道结构基本不变,晶胞的收缩和非骨架铝在孔道内的沉积,不足以严重限制甲醇胺化产物三甲胺在孔道内的进出;且在改性后,由于非骨架铝在孔道内的沉积,分子筛内表面的微环境发生了变化,致使有些活性位不利于三甲胺的吸附和生成,从而有利于进一步提高目的产物二甲胺的选择性.  相似文献   

6.
采用密度泛函理论和模型簇法研究了噻吩和沸石分子筛桥羟基和硅羟基的相互作用.对噻吩吸附在硅羟基H3SiOH可能的两种配位方式及吸附在沸石模型簇H3Si(OH)Al(OH)2OSiH3桥羟基B酸上可能的两种配位方式进行了比较分析.所有模型簇采用B3LYP混合方法对氢原子在6-31G基组水平上,对硅原子、铝原子、氧原子、碳原子、硫原子在6-31 G(d)基组水平上进行了全优化和频率分析.着重考察了噻吩与硅羟基及分子筛桥羟基模型簇不同配位方式所形成的配合物的结构及能量变化.计算结果表明由于在形成沸石-噻吩和硅羟基-噻吩配合物的结构和性质变化不明显,所以它们之间的相互作用为范德华作用力.从噻吩在沸石分子筛的桥羟基和硅羟基与噻吩的相互作用的吸附热可以推断,噻吩优先吸附在桥羟基上,只有桥羟基吸附饱和后方吸附在硅羟基上.由频率分析结果和实验结果的一致性可以证明所推测吸附模型的正确性.  相似文献   

7.
采用Dmol3程序中密度泛函理论(DFT)的广义梯度方法GGA/BLYP和DND基组研究了银离子交换的丝光沸石([AgJ-AIMOR)结构及其对NOx分子吸附性能的影响,获得吸附复合物的平衡儿何结构参数、吸附能以及红外振动频率等数据.结果表明,NO,分子与丝光沸石间的主要作用力为NOx分子中的氮(或氧)原子上的孤对电子和Ag+间的静电作用力.吸附能数据表明,NOx分子以η1-N模式吸附在[Agl-AIMOR 分子筛中的结构更稳定;在η1-N 模式中,NOx分子吸附作用强度的次序为 NO>N02>N2O.红外振动频率结果表明,吸附态NOx分子中 N-O 和N-N 键伸缩振动频率的位移趋势与 N-O 和 N-N 键变化规律基本相一致.另外,对 [Ag]-A1MOR分子筛的抗硫、抗水及抗氧化性能也进行了研究和分析.  相似文献   

8.
报道对氨(NH3母体)、甲胺(CH3NH2)、二甲胺[(CH3)2NH]、三甲胺[(CH3)3N]与三氯甲烷(CHCl3)形成的系列复合物的理论研究结果。把复合物看作一个超分子,在B3LYP/6-311G(d,p)的水平上进行密度泛函法计算,并运用完全均衡校正法进行基组超位误差校正(BSSE)。探讨该系列复合物的电子结构与相关性质,如稳定性、电荷转移及主要几何参数的变化规律等,结果表明,形成复合物的稳定性次序为NH3-CHCl3(Ⅰ)>CH3NH2-CHCl3(Ⅱ)>(CH3)2NH-CHCl3(Ⅲ)>(CH3)3N-CHCl3(Ⅳ)。形成复合物的过程包含着电荷转移。该系列复合物的稳定性与电荷转移量、前线轨道能量差△εL-H及广义H键距离良好的线性关系,与结合点的电荷布居也有密切的关系,复合物的稳定性是分子间共价作用和静电作用两方面因素综合的结果。计算结果能较好地解释有关的实验现象和规律。  相似文献   

9.
高比表面胺基吸附树脂的合成及其性能研究   总被引:1,自引:0,他引:1  
以具有高比表面积的后交联大孔共聚物为基础,进-步和三甲胺、二甲胺、α-甲基吡啶等有机胺类进行胺化反应,引入功能基,从而制得一类带有离子交换功能的大孔吸附树脂.其物理和化学结构测定证实这类树脂既具有高比表面,又带有一定数量的交换基团.并研究了它们对苯酚和Au(I)的吸附-脱附性能.  相似文献   

10.
采用Dmol3程序中密度泛函理论(DFT)的广义梯度方法GGA/BLYP和DND基组研究了银离子交换的丝光沸石([Ag]-AlMOR)结构及其对NOx分子吸附性能的影响, 获得吸附复合物的平衡几何结构参数、吸附能以及红外振动频率等数据. 结果表明, NOx分子与丝光沸石间的主要作用力为NOx分子中的氮(或氧)原子上的孤对电子和Ag+间的静电作用力. 吸附能数据表明, NOx分子以η1-N模式吸附在[Ag]-AlMOR分子筛中的结构更稳定; 在η1-N模式中, NOx分子吸附作用强度的次序为NO>NO2>N2O. 红外振动频率结果表明, 吸附态NOx分子中N—O和N—N键伸缩振动频率的位移趋势与N—O和N—N 键变化规律基本相一致. 另外, 对[Ag]-AlMOR分子筛的抗硫、抗水及抗氧化性能也进行了研究和分析.  相似文献   

11.
To perfect a method for building a theoretical hydrogen-bond basicity scale, the enthalpy of hydrogen bonding between methanol and thirteen neutral and anionic bases (MeOH, MeNH2, Me2NH, Et2NH, Me3N, Et3N, Br-, CN-, SH-, Cl-, HCOO-, MeO-, F-) was calculated by DFT and ab initio methods. The theoretical results were compared to selected experimental ones. It appears that B3LYP/6-31+G(d,p) calculations are satisfactory for optimizing the geometry of complexes and giving a general order of basicity. However, they are deficient for reproducing the large effect of alkyl groups on the hydrogen-bond basicity of amines. This deficiency is explained by intermolecular perturbation theory calculations, which show that the alkylation of nitrogen dramatically increases the dispersion energy component not taken into account by the B3LYP functional. Of the methods considered, only MP2/aug-cc-pVTZ calculations are capable of reproducing the binding enthalpy within the experimental error for the first-row acceptor atoms N, O, and F, and of accounting for dispersion effects created by alkylation at the hydrogen-bond acceptor site.  相似文献   

12.
The (benzophenone imine)platinum(II) compounds trans-[PtCl2(Ph2C=NH)(RR'SO)] [R, R'=Me, Me (2); n-Pr, n-Pr (3); (CH2)4 (4); Me, Ph (5); Me, p-MeC6H4 (6)] were prepared by the reaction of Ph2C=NH with K[PtCl3(RR'SO)], obtained in situ from K2[PtCl4] and the corresponding sulfoxide, giving 2-6 as well as cis-[PtCl2(Ph2C=NH)2] (1) as a minor product. The complexes were characterized by 1H, 13C, and 195Pt NMR and IR spectroscopy, electrospray ionization mass spectrometry, and C, H, and N elemental analysis. The X-ray crystallography of 1 enables confirmation of the cis configuration of the complex, while in 2 and 4.1/2CHCl3, the imine and sulfoxide ligands are mutually trans. The solid-state structure of 4.1/2CHCl3 consists of two dimeric Pt moieties representing a rather weak Pt...Pt interaction. The dimeric architecture of 4.1/2CHCl3 is enhanced by the hydrogen bonding between imine H atoms and O atoms. The orthometalation of 1 and 2-6 proceeds both in the solid phase and in a toluene suspension, leading to the formation of [PtCl{Ph(C6H4)C=NH}(Ph2C=NH)] (7) and [PtCl{Ph(C6H4)C=NH}(RR'SO)] (8-12), respectively, isolated in nearly quantitative yields. Complexes 8-12 are emissive at room temperature both in solution (lambdaemmax approximately 535 nm) and in the solid state (lambdaemmax 560-610 nm), with excited-state lifetimes of ca. 300-600 ns, representing a new family of PtII-based luminescent complexes. Compounds 8 and 10 have been characterized by X-ray analysis, confirming the square-planar coordination geometry of the metal center with the almost planar platinacycles. In 8, the asymmetric unit contains two independent Pt molecules, while in 10, it includes four Pt molecules linked by the intermolecular hydrogen-bonding network between the NH group and Cl atoms.  相似文献   

13.
A theoretical study of amines adsorption in HMOR by using ONIOM2 method   总被引:1,自引:0,他引:1  
The two-layered ONIOM method is used to study the interaction of amines (NH3, MeNH2, Me2NH and Me3N) with H-type mordenite (HMOR). For all the calculations, the high-layer is described by the B3LYP/6-31G(d,p) method, while the HF/3-21G method is used for the low-layer. In the adsorption complexes, proton transfer from the HMOR framework to amines is observed, and the protonated amines (R3NH+) are stabilized by hydrogen bonding between the negatively charged zeolite framework and the N---H bonds. The strength of the OH---N hydrogen bonding is reflected by differences in the N---H stretching frequency of R3NH+ between the adsorbed state and the gas phase. The relative order of the amine basicity on the basis of the computed adsorption energies agrees well with the experiments, but differs from those in the gas phase (proton affinity) and in solvents (pKa).  相似文献   

14.
Most simple cis-PtA2G2 complexes that model the G-G cross-link DNA lesions caused by the clinically used anticancer drug cis-PtCl2(NH3)2 undergo large fluxional motions at a rapid rate (A2 = two amines or a diamine; G = guanine derivative). The carrier amine ligands in active compounds have NH groups, but the fundamental role of the NH groups has been obscured by the dynamic motion. To assess carrier ligand effects, we examine retro models, cis-PtA2G2 complexes, in which dynamic motion has been reduced by the incorporation of steric bulk into the carrier ligands. In this study we introduce a new approach employing the chirality-neutral chelate (CNC) ligand, Me2ppz (N,N'-dimethylpiperazine). Because they lie in the Pt coordination plane, the methyl groups of Me2ppz do not clash with the 06 of the base of G ligands in the ground state, but such clashes sterically hinder dynamic motion. NMR spectroscopy provided conclusive evidence that Me2ppzPt(GMP)2 complexes (GMP = 5'- and 3'-GMP) exist as a slowly interconverting mixture of two dominant head-to-tail (HT) conformers and a head-to-head (HH) conformer. Since the absence of carrier ligand chirality precluded using NMR methods to determine the absolute conformation of the two HT conformers, we used our recently developed CD pH jump method to establish chirality. The most abundant HT Me2ppzPt(5'-GMP)2 form had A chirality. Previously this chirality was shown to be favored by phosphate-cis G NIH hydrogen-bonding interligand interactions; such interactions also favor the HT conformers over the HH conformer. For typical carrier ligands, G O6 and phosphate interactions with the carrier ligand NH groups also favor the HT forms. These latter interactions are absent in Me2ppzPt(GMP)2 complexes, but the HT forms are still dominant. Nevertheless, we do find the first evidence for an HH form of a simple cis-PtA2G2 model with A2 lacking any NH groups. In previous studies, the absence of the HH conformer in cis-PtA2G2 complexes lacking carrier NH groups may be due to the presence of out-of-plane carrier ligand bulk. Such bulk forces both G O6-G O6 and G O6-carrier ligand clashes, thereby disfavoring the HH form. The major DNA cross-link adduct has the HH conformation. Thus, for anticancer activity, the small bulk of the NH group may be more important than the H-bonding interaction.  相似文献   

15.
Ab initio calculations at MP2/6-311++G(2d,2p) and MP2/6-311++G(3df,3pd) computational levels have been used to analyze the interactions between nitrous oxide and a series of small and large molecules that act simultaneously as hydrogen bond donors and electron donors. The basis set superposition error (BSSE) and zero point energy (ZPE) corrected binding energies of small N2O complexes (H2O, NH3, HOOH, HOO*, HONH2, HCO2H, H2CO, HCONH2, H2CNH, HC(NH)NH2, SH2, H2CS, HCSOH, HCSNH2) vary between -0.93 and -2.90 kcal/mol at MP2/6-311++G(3df,3pd) level, and for eight large complexes of N2O they vary between -2.98 and -3.37 kcal/mol at the MP2/6-311++G(2d,2p) level. The most strongly bound among small N2O complexes (HCSNH2-N2O) contains a NH..N bond, along with S-->N interactions, and the most unstable (H2S-N2O) contains just S-->N interactions. The electron density properties have been analyzed within the atoms in molecules (AIM) methodology. Results of the present study open a window into the nature of the interactions between N2O with other molecular moieties and open the possibility to design N2O abiotic receptors.  相似文献   

16.
The gas-phase reactions between ethylenediamine (en) and Cu(+) have been investigated by means of mass spectrometry techniques. The MIKE spectrum reveals that the adduct ions [Cu(+)(H(2)NCH(2)CH(2)NH(2))] spontaneously decompose by loosing H(2), NH(3) and HCu, the loss of hydrogen being clearly dominant. The spectra of the fully C-deuterated species show the loss of HD, NH(3) and CuD but no losses of H(2), D(2), NH(2)D, NHD(2), ND(3) or CuH are observed. This clearly excludes hydrogen exchange between the methylene and the amino groups as possible mechanisms for the loss of ammonia. Conversely, methylene hydrogen atoms are clearly involved in the loss of molecular hydrogen. The structures and bonding characteristics of the Cu(+)(en) complexes as well as the different stationary points of the corresponding potential energy surface (PES) have been theoretically studied by DFT calculations carried out at B3LYP/6-311+G(2df,2p)//B3LYP/6-311G(d,p) level. Based on the topology of this PES the most plausible mechanisms for the aforementioned unimolecular fragmentations are proposed. Our theoretical estimates indicate that Cu(+) strongly binds to en, by forming a chelated structure in which Cu(+) is bridging between both amino groups. The binding energy is quite high (84 kcal mol(-1)), but also the products of the unimolecular decomposition of Cu(+)(en) complexes are strongly bound Cu(+)-complexes.  相似文献   

17.
环双(对-蒽基-对草快)的分子识别与谱学性质   总被引:1,自引:0,他引:1  
环双(对-蒽基-对草快)是一种新型的缺电子大环仿生主体, 分子识别是其最重要的应用之一. 考察主体对一系列客体分子如水、氨、醇及杂环等的识别能力, 用密度泛函理论(DFT)中的B3LYP/3-21G基组对主客体复合物的结构进行优化. 在B3LYP/6-31G(d)水平上进行单点能计算, 校正后得到复合物的结合能. 用B3LYP/3-21G方法计算13C和3He化学位移. 结果表明, 主体对客体分子的识别主要靠客体上的杂原子与主体上的氢原子之间的氢键进行. 复合物的稳定化能受氢键的数目和距离影响. 氢键的形成导致部分复合物LUMO与HOMO能隙增大, 同时导致与氢键相连的C—H键上C原子的化学位移向低场移动. 复合物的芳香性与其结合能的大小及结合方式有关. 主体的芳香性因其与客体之间的弱相互作用而提高, 但太强的相互作用及客体在主体空腔内都将影响主体的环电流, 从而削弱其芳香性.  相似文献   

18.
Several series of hydrogen- and dihydrogen-bonded complexes with HCN, C2H2, HF, H2O, CH3CONH2, and CH3COOH as donors and H2O, MeOH, EtOH, MeOMe, NH3, NH2Me, NHMe2, NMe3, NEtMe2, and BH3-NMe3 as acceptors were investigated using the MP2/6-311++G(d,p) level of theory. The total lowering of the X-H stretching frequencies in the hydrogen-bonded complexes were linearly correlated with the proton affinities of the accepting bases. From comparison of hydrogen- and dihydrogen-bonded complexes, a scaling factor to estimate the exact proton affinity of a dihydrogen bond acceptor was developed. Further, the scaling factor involving linear donors (1.204) is marginally higher than that involving nonlinear donor molecules (1.162). Finally, it was found that, given identical conditions, a hydrogen bond will be about 16-20% stronger than a corresponding dihydrogen bond.  相似文献   

19.
The density functional theory and the cluster model methods have been employed to investigate the interactions between ethanethiol and HZSM-5 zeolites. Molecular complexes formed by the adsorption of ethanethiol on silanol H3SiOH with two coordination forms, model Bronsted acid sites of zeolite cluster H3Si(OH)Al(OH)2SiH3 interaction with ethanethiol, aluminum species adsorbed ethanethiol have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using B3LYP hybrid method at 3-21G basis level for hydrogen atoms and 6-31G(d) basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms of H3Si(OH)Al(OH)2SiH3-ethanethiol, silanol-ethanethiol and Al(OH)3-ethanethiol have been studied. The calculated results showed the nature of interactions was van der Waals force as exhibited by not much change in geometric structures and properties. The preference order of ethanethiol adsorbed on HZSM-5 zeolite may be residual aluminum species, bridging hydroxyl groups and silanol OH groups from the adsorption heat. The adsorbed models of protonized ethanethiol on bridging hydroxyl OH groups and linear hydrogen bonded ethanethiol on bridging OH groups suggested in literature might not exist as revealed by this theoretical calculation. Possible adsorption models were obtained for the first time.  相似文献   

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