核磁共振法(NMR)和pH法研究Zn(Ⅱ)与HEDP(1-羟基乙叉-1,1-二膦酸)的配合物

本文用核磁共振法(NMR)和pH法对Zn(Ⅱ)与1-羟基乙叉-1,1-二膦酸(1-hydroxyethylidenel,1-diphosphonic acid,简称HEDP,以H_4L表示)的配合物进行了研究,由于pH<7时溶液中有沉淀生成,故NMR的研究是在溶液pH>7时进行.测定了溶液中不同Zn(Ⅱ)/HEDP摩尔比和pH值时~(?)PNMR的化学位移。研究结果表明在pH7.5-11.0范围内生成Zn(Ⅱ)/HEDP=1(摩尔比)组成的配合物,在pH11.8-12.3范围内生成Zn(Ⅱ)/HEDP=2(摩尔比)组成的配合物,分别用pH法和NMR法测定了上述组成配合物的稳定常数.结果如下: logK_([zn(HL)~-]) logK_([znL~(2-)]) logK_([zn,L]) pH法 4.69 7.51 11.63 NMR法——6.88-7.19 12.44     

甲磺酸多沙唑嗪的合成

甲磺酸多沙唑嗪(doxazosin mesylate,Ⅰ)的化学名为1-(4-氨基-6,7-二甲氧基-2-喹唑啉基)-4-(1,4-苯骈二恶烷-2-甲酰基)哌嗪甲磺酸盐,是一种新型的高选择性α1受体阻滞剂[1],半衰期长,且有明显的降压和降脂作用,同时对单纯性前列腺增生引起的排尿困难具有良好的作用.目前已成为国内外治疗轻中度高血压的一线药物[2,3,4].     

多沙唑嗪与血清白蛋白的作用及血清中多沙唑嗪含量的荧光测定法研究

用荧光光度法研究了降血压药物多沙唑嗪与血清白蛋白的相互作用,救 是不同温度下药物与血清白蛋白相互作用的形成常数;讨论了微量金属离子对药物与血清白蛋白形成常数的影响,并根据热力学常数确定了该药物与血清白蛋白之间的作用力类型为疏水作用力;研究了多沙唑嗪的适宜条件并成功应用于血样中含量的测定。     

^(1)H和^(19)F核磁共振定量法测定诺氟沙星标准品的绝对含量EI北大核心CSCD

采用^(1)H和^(19)F核磁共振定量法测定诺氟沙星标准品的绝对含量。^(1)H核磁共振定量法以DMSO-d6为溶剂,诺氟沙星峰(δ7.9)为定量峰,马来酸峰(δ6.3)为内标峰。在脉冲程序zg30,采样时间4.09 s,延迟时间20 s,扫描次数为16的条件下采集氢谱。^(19)F核磁共振定量法以利培酮为内标物,诺氟沙星峰(δ-121.3)为定量峰,利培酮峰(δ-109.9)为内标峰。在脉冲程序zgfhigqn.2,延迟时间7 s,扫描次数为16的条件下采集氟谱。^(1)H和^(19)F核磁共振定量法测定结果接近,且与质量平衡法测定结果一致。核磁共振定量法可用来测定诺氟沙星绝对含量,快速、简单高效、且不需要对照品。     

H+H2体系的态(R)-态(TS)-态(P)理论研究

H+H₂体系的辛准经典轨迹(SQCT)计算表明: 碰撞轨迹分为A, B两种类型, A型是经过过渡态鞍点的, B型是不经过过渡态鞍点的. A型轨迹不全发生反应, B型轨迹却也可发生反应. A, B两种类型轨迹的配分及其反应性, 与反应物初始态(R)有关. 这种轨迹类型A, B影响着产物态(P)(即振转态)分布及其角度分布. 初步建立了化学反应态(R)-态(TS)-态(P)理论研究的雏形, 深化了对Eyring过渡态理论的理解.     

2-(2-氨基-3-吡啶基)-苯并咪唑的合成、晶体结构和荧光特性研究

在合成2-(2-氨基-3-吡啶基)-苯并咪唑的基础上,利用NMR(1H、13C、COSY、HSQC和HMBC)、MS、IR和UV进行了详细表征;通过X-ray单晶衍射仪测定了该化合物的晶体结构,实验结果表明该晶体属于三方晶系(空间群R3,a=1.833 7(3)nm,b=1.833 7(2)nm,c=1.777 7(4)nm,V=5.176 4(15)nm3,Z=18),很好地支持了波谱表征的结果。同时,结合密度泛函计算,研究了2-(2-氨基-3-吡啶基)-苯并咪唑的荧光光谱。结果表明,化合物的双荧光不是由同一种异构体发射的,而是来源于不同异构体:长波区500~600 nm的荧光由K构型发射,短波区350~450 nm的发射由异构体E1和E2共同产生,理论预测的光谱与实验一致。     

基于5-(4-(2,6-二(2-吡啶基)-4-吡啶基)苯氧基)间苯二甲酸的Ni(Ⅱ)和Cd(Ⅱ)配位聚合物的合成与晶体结构

用溶剂热法合成了2个以5-(4-(2,6-二(2-吡啶基)-4-吡啶基)苯氧基)间苯二甲酸(H₂L)为配体的金属-有机配位聚合物:{[NiL(H₂O)]·H₂O}_n(1),[CdL(phen)]_n(2)。通过X-射线单晶衍射,元素分析和红外光谱进行了结构表征。结构分析表明,在1中,L^2-配体的2个羧基氧原子桥连相邻的2个Ni(Ⅱ)离子,形成平行于a轴的一维链,链间则通过吡啶氮原子与金属离子连接,最终形成具有(4,4)-连接三维网络结构。在2中,Cd(Ⅱ)为七配位的单帽三棱柱几何构型,L^2-配体通过2个羧基和1个吡啶基与3个中心金属Cd(Ⅱ)相连,形成(3,3)-连接的二维层面结构,又通过面间的π…π堆积作用形成了3D超分子结构。测定了配位聚合物的热稳定性和2的荧光性质。     

基于5-(4-(2,6-二(2-吡啶基)-4-吡啶基)苯氧基)间苯二甲酸的Ni(Ⅱ)和Cd(Ⅱ)配位聚合物的合成与晶体结构

用溶剂热法合成了2个以5-(4-(2,6-二(2-吡啶基)-4-吡啶基)苯氧基)间苯二甲酸(H_2L)为配体的金属-有机配位聚合物:{[NiL(H_2O)]·H_2O}_n(1),[Cd L(phen)]_n(2)。通过X-射线单晶衍射,元素分析和红外光谱进行了结构表征。结构分析表明,在1中,L~(2-)配体的2个羧基氧原子桥连相邻的2个Ni(Ⅱ)离子,形成平行于a轴的一维链,链间则通过吡啶氮原子与金属离子连接,最终形成具有(4,4)-连接三维网络结构。在2中,Cd(Ⅱ)为七配位的单帽三棱柱几何构型,L2-配体通过2个羧基和1个吡啶基与3个中心金属Cd(Ⅱ)相连,形成(3,3)-连接的二维层面结构,又通过面间的π…π堆积作用形成了3D超分子结构。测定了配位聚合物的热稳定性和2的荧光性质。     

二萜生物碱的~(13)C核磁共振谱

本文通过对186个二萜生物碱及其衍生物的~(13)C NMR谱数据的分析比较,就以下几方面作了归纳总结:①信号归属的方法;②常见取代基OCH_3、NCH_3、、NCH_2CH_3、OCOCH_3、的化学位移范围;③季碳和某些特定碳的化学位移规律。某些特定结构,如C_(20)二萜生物碱中的噁唑烷环以及C_(20)差向异构体等的~(13)C NMR谱特征;④C_(19)二萜生物碱中不同位置上取代基(H→OH、H→OMe、OH→OAc、OH→OMe、OH→C=O)效应和立体化学效应。这些归纳总结有助于此类化合物结构的阐明。     

由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法

苄氧乙基环氧乙烷;不对称合成;由(S)-和( R )-天冬氨酸合成( R )-和(S)-(2-苄氧乙基)环氧乙烷的改良方法     

C60O2可能异构体的结构,电子光谱和NMR谱的理论研究

用ＩＮＤＯ系列方法研究Ｃ６０Ｏ２可能异构体的结构，两个氧原子分别加在两个六元环相邻边或五六元环相邻边形成环氧结构，为Ｃｓ对称性，得６种可能构型，计算表明，两个氧原子加在同个六元环的六六元环相邻边所形成环氧结构Ｃｓ构型最稳定，环氧处Ｃ－Ｃ键不断开，与实验结果一致，其电子光谱计算结果亦与实验值相吻合，这种Ｃｓ构环氧结构所在六元环上的另一个Ｃ－Ｃ键有大的键序，为高活性位置，因此Ｃ６０Ｏ２可能有较好的化学     

Molecular structure and vibrational assignment of melaminium phthalate by density functional theory (DFT) and ab initio Hartree-Fock (HF) calculations

The molecular geometry, the normal mode frequencies and corresponding vibrational assignment of melaminium phthalate (C₃H₇N₆⁺·C₈H₅O₄⁻) in the ground state were performed by HF and B3LYP levels of theory using the 6-31G(d) basis set. The optimized bond length numbers with bond angles are in good agreement with the X-ray data. The vibrational spectra of melaminium phthalate which is calculated by HF and B3LYP methods, reproduces vibrational wave numbers with an accuracy which allows reliable vibrational assignments. The title compound has been studied in the 4000–100 cm⁻¹ region where the theoretical evaluation and assignment of all observed bands were made.     

Experimental and Theoretical Vibrational Study of the Oxotetrachlorochromate(V) Anion in [AsPh4][CrOCl4]

Infrared and Raman spectra were obtained for tetraphenylarsonium oxotetrachlorochromate(V), [AsPh₄][CrOCl₄]. Equilibrium geometry and vibrational frequencies for the anion, CrOCl₄^?, were studied employing Density Functional Theory (DFT) methods. A comparative theoretical study was performed in order to determine the best level of theory and basis set to reproduce the experimental structure parameters and vibrational frequencies. Such frequencies served as a basis for the calculation of the scaled quantum mechanical (SQM) force field for the anion. The obtained results were compared with those obtained previously for the VOCl₄^? anion.     

Experimental and Quantum Chemical Studies of 5-Fluoroisatin-3-(N-Cyclohexylthiosemicarbazone) and Its Metal Complexes

Abstract

Zn(II) and Ni(II) complexes of 5-fluoroisatin-3-[-(N-cyclohexylthiosemicarbazone)] (H₂FIC) have been prepared and characterized structurally by means of elemental analyses, FTIR, electronic, and ¹H NMR spectra. The theoretical wavenumbers, IR intensities, and molecular parameters have been calculated by the ab-initio Hartree–Fock (HF) method with the LanL2DZ basis set. The theoretical wavenumbers show a good agreement with experimental data. The bond lengths, bond angles, the highest occupied molecular orbital energy (E_HOMO), the lowest unoccupied molecular orbital energy (E_LUMO), the energy gap between E_HOMO and E_LUMO (ΔE_HOMO-LUMO), dipole moment, and charges on the atoms of H₂FIC as monomer form were studied by the density functional theory/Becke-3-Lee-Yang-Parr (DFT/B3LYP) and ab-initio HF methods using 6-31G(d,p) basis set. The trimeric possible structure of H₂FIC was also investigated using HF method. The observed IR wavenumbers of the H₂FIC were analyzed in the light of the computed vibrational spectra of its monomer and trimer forms.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis and Chemical Shifts Calculation of a-Acyloxycarboxamides Derived from Indane-l,2,3-trione by DFT and HF Methods

α-Acyloxycarboxamides are synthesized from three-component Passerini reaction between indane-1,2,3-trione, isocyanides, and thiophenecarboxylic acids in quantitative yields. The structures of the final products were confirmed by IR, 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. The B3LYP/HF calculations for computation of 1H and 13C NMR chemical shifts have been carried out for the title compounds at the 6-311+G** and 6-311++G** basis set levels within GIAO and CSGT approaches. Predicted 1H and 13C NMR che-mical shifts have been assigned and compared with experimental 1H and 13C NMR spectra and they are supported each other.     

铂配合物与DNA碱基对间相互作用的理论研究

用量子化学方法研究一系列Pt(II)配合物作用于嘌呤碱基N7位点后对Watson-Crick碱基对AT、GC的影响. 计算结果显示铂配体与碱基对AT、GC的作用以静电作用为主，同时极化作用也是影响GC碱基对的重要因素. 静电作用极大地增强了铂化嘌呤碱基与嘧啶碱基间的相互作用，而嘌呤碱基与嘧啶碱基间作用与未铂化碱基对作用相近. Pd(II) 和 Ni(II)的相关研究得到类似的结果. 碱基对间氢键作用“二阶微扰能”分析结果与氢键强弱变化一致.     

Molecular structure and vibrational spectra of N-mesylhydroxylamin and N-mesyl-O-methylhydroxylamin by density functional theory and ab initio Hartree–Fock calculations

The molecular geometry and vibrational frequencies of N-mesylhydroxylamin (N-MHN) and N-mesyl-O-methylhydroxylamin (N-MMHN) in the ground state have been calculated using the Hartree–Fock and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric band lengths and bond angles obtained by using HF and DFT (B3LYP) show the best agreement with the experimental data. Comparison of the observed fundamental vibrational frequencies of N-MHN and N-MMHN and calculated results by density functional B3LYP and Hartree–Fock methods indicate that B3LYP is superior to the scaled Hartree–Fock approach for molecular vibrational problems.     

Theoretical Study of the Metal–Metal Interaction in Dipalladium(I) Complexes

Correlated ab initio calculations have been performed on three dipalladium(I) complexes. These compounds differ both by the metal–metal interaction and by the metal–ligand interaction. The [Pd₂Cl₂(μ −H₂PCH₂PH₂)₂] complex exhibits a σ overlap between the two binding metallic orbitals and has no bridging ligand. In [Pd₂Cl₄(μ −CO)₂]²⁻, the leading interaction between the two palladium involves a π overlap between the metallic orbitals and goes through the two bridging CO ligands. In [Pd₂Cl₂(μ −CO)(μ −H₂PCH₂ PH₂)₂], a single CO ligand bridges the two palladium atoms which interact through a hybrid σ–δ overlap. The three compounds also differ by the metal–metal distances. Surprisingly enough, while the palladium atoms are formally d ⁹ in all these complexes, none of them is paramagnetic. We propose here a detailed analysis of the electronic structures of these compounds and rationalize their chemical structures as well as the role of back-donation in the CO bridged compounds. Finally, since highly correlated treatments are used to describe these complexes, a detailed study of the role of both non-dynamical and dynamical correlations is performed. Concerning the [Pd₂Cl₄(μ −CO)₂]²⁻ complex, this analysis has revealed that the complex is not bound at the lowest correlated levels of calculation and therefore dynamical correlation is alone responsible for its binding energy.     

Adducts of nitrogenous ligands with rhodium(II) tetracarboxylates and tetraformamidinate: NMR spectroscopy and density functional theory calculations

Complexation of tetrakis(μ₂‐N,N'‐diphenylformamidinato‐N,N')‐di‐rhodium(II) with ligands containing nitrile, isonitrile, amine, hydroxyl, sulfhydryl, isocyanate, and isothiocyanate functional groups has been studied in liquid and solid phases using ¹H, ¹³C and ¹⁵N NMR, ¹³C and ¹⁵N cross polarisation–magic angle spinning NMR, and absorption spectroscopy in the visible range. The complexation was monitored using various NMR physicochemical parameters, such as chemical shifts, longitudinal relaxation times T₁, and NOE enhancements. Rhodium(II) tetraformamidinate selectively bonded only unbranched amine (propan‐1‐amine), pentanenitrile, and (1‐isocyanoethyl)benzene. No complexation occurred in the case of ligands having hydroxyl, sulfhydryl, isocyanate, and isothiocyanate functional groups, and more expanded amine molecules such as butan‐2‐amine and 1‐azabicyclo[2.2.2]octane. Such features were opposite to those observed in rhodium(II) tetracarboxylates, forming adducts with all kind of ligands. Special attention was focused on the analysis of Δδ parameters, defined as a chemical shift difference between signal in adduct and corresponding signal in free ligand. In the case of ¹H NMR, Δδ values were either negative in adducts of rhodium(II) tetraformamidinate or positive in adducts of rhodium(II) tetracarboxylates. Experimental findings were supported by density functional theory molecular modelling and gauge independent atomic orbitals chemical shift calculations. The calculation of chemical shifts combined with scaling procedure allowed to reproduce qualitatively Δδ parameters. Copyright © 2013 John Wiley & Sons, Ltd.