Theoretical Study of Halogen Effect in Isomerization of 2-Halo-[9]-annulen Anion at the DFT Level

Cis-trans isomerization of [9]-annulenanion(1) and its 2-fluoro-,2-chloro-and 2-bromo-derivatives(2,3 and 4,respectively) were investigated at the HF/6-31G* and B3LYP/6-311++G** levels of theory.Cis,cis,cis,cis structures appear more stable than their corresponding cis,cis,cis,trans-isomers.The relative height of energy barriers for cis-trans isomerization is:2cis > 1cis > 3cis > 4cis.This trend for the reverse trans-cis isomerization follows the electronegativity of the substituent at C-2(2trans > 3trans > 4trans > 1trans).     

杯[4]吡咯-阴离子体系相互作用的理论研究——杯[4]吡咯-卤素阴离子体系的密度泛函研究

用密度泛函B3LYP/LANL2DZ方法对自由杯[4]吡咯的最低能量构象和卤素阴离子-杯[4]吡咯复合物进行了计算研究.结果表明,杯[4]吡咯与卤素离子能通过彼此间的相互作用形成复合物,并且这种相互作用在本质上应为分子间的氢键相互作用;杯[4]吡咯与卤素阴离子形成的复合物在构型变化、电荷转移、前线轨道及其作用方式、成键布居以及能量和热力学参数等方面均按元素周期律有规律地变化,杯[4]吡咯与卤素阴离子间的相互作用沿元素周期依次减少.     

新型受体呋喃并[3’,4’:5,6]吡啶并[2,3-c]吡唑的合成及对阴离子的识别研究

设计并合成了5种呋喃并[3’,4’:5,6]吡啶并[2,3-c]吡唑受体分子, 利用紫外-可见吸收光谱考察了其与F－, Cl－, Br－, AcO－, 等阴离子的作用. 结果表明该类受体分子与阴离子形成氢键配合物, 导致呋喃并吡啶并吡唑受体的光谱发生变化. 测定了配合物的结合比和稳定常数, 发现受体化合物对F－, AcO－离子具有良好的选择性, 对其它多种阴离子无影响. Job曲线表明受体分子与阴离子间形成1∶1型的配合物.     

Efficient Synthesis of a New Family of 2,6-Disulfanyl-9-selenabicyclo[3.3.1]nonanes

The efficient synthesis of a new family of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes in high yields has been developed based on 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion generated from bis-isothiouronium salt of 2,6-dibromo-9-selenabicyclo[3.3.1]nonane. The derivatives of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonane containing alkyl, allyl and benzyl moieties have been prepared in 90–99% yields by nucleophilic substitution of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion with alkyl, allyl and benzyl halides. The reaction of nucleophilic addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to alkyl propiolates afforded 2,6-di(vinylsulfanyl)-9-selenabicyclo[3.3.1]nonanes. The conditions for regio- and stereoselective addition of 9-selenabicyclo[3.3.1]nonane-2,6-dithiolate anion to a triple bond of alkyl propiolates have been found. To date, not a single representative of 2,6-disulfanyl-9-selenabicyclo[3.3.1]nonanes has been described in the literature.     

One-pot synthesis of oxygen and nitrogen-bridged calix[2]arene[2]triazines

A simple and powerful one-pot reaction method was developed for the synthesis of heteracalixaromatics. In the presence of a base, one-pot macrocyclic condensation reaction between cyanuric chloride and 1,3-phenylene diols and diamines proceeded effectively under very mild conditions to afford a number of functionalised oxygen and nitrogen-bridged calix[2]arene[2]triazines in 33–54% yields. The method was applied in a multigram-scale (14.4 g) preparation of tetraoxacalix[2]arene[2]triazine.     

Construction of a hetero pseudo[2]rota[2]catenane

A novel ammonium template containing three ammonium sites was synthesized. Two ammoniums located on the linear component served as template for cucurbit[6]uril to form the CB-based pseudo[2]rotacane while another one located on the macrocyclic component played a role of template for clipping reaction. As a result of a ‘‘threading-followed-by-clipping' approach, a novel hetero pseudo[2]rota[2]catenane was successfully constructed.     

2-芳基-4-氧-4 H-吡喃酮[3,2-c]-9-溴喹啉类化合物的合成

黄酮类化合物广泛存在于埴物体中,具有广泛的生物活性,其研究发展很快,但对于氮杂黄酮类化合物的研究工作却甚少。含氮黄酮类化合物具有抗癌、抗菌、冠状动脉扩张等作用。但是,目前黄酮类药物仍存在以下问题:(1)黄酮类化合物结构繁多,生物活性极其广泛,但作用强度普遍较弱;(2)黄酮类化合物水溶性较低,影响药物的吸收与疗效。新型黄酮类化合物的合成仍有一定的意义。     

Synthesis and Anticonvulsant Activity of 9-Alkoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3[5H]-ones

A series of novel 9-alkoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one derivatives was designed and synthesized starting from 2,3,4,5-tetrahydro-7-hydroxy-1H-2-benzazepin-1-one. The structures of these compounds were confirmed by mass, ¹H NMR infrared spectra, and elemental analysis. Their anticonvulsant activity was evaluated by maximal electroshock (MES) test, and their neurotoxic effects were determined by the rotarod neurotoxicity test. The results shown that 3k was the most active compound with median effective dose (ED₅₀) of 27.3 mg/kg, median toxicity dose (TD₅₀) of 118.3 mg/kg, and protective index (PI) of 4.3. Possible structure–activity relationship is discussed.     

毛细管电泳研究杯[4]吡咯和二吡咯化合物对无机阴离子的识别作用

Capillary electrophoresis （CE） can separate charged and neutral substances with high speed and efficiency. In this paper, utilizing meso-octamethylcalix[4]pyrrole, meso-tetraspirocyclohexylcalJx[4]pyrrole, bimethyl bi（2-pyrryl）- methane and 1,1-bi（2-pyrryl）cyclohexane as additives in capillary zone electrophoresis （CZE） electrolyte, their recognition ability to inorganic anions was discussed. The dipyrrylmethanes have better recognition ability than others. Their effects on separation of seven normal inorganic anions by CZE were studied.     

Theoretical Studies on the Intermolecular Interactions of Aza-calix[2]arene[2]-triazines with RDX

Six fully optimized structures of the aza-calix[2]arene[2]-triazines/RDX supramo-lecular complexes have been obtained at the DFT-B3LYP/6-311++G** level,and the corresponding intermolecular interactions have been investigated using the B3LYP,mPWPW91 and MP2 methods at the 6-311++G** level,respectively.The natural bond orbital(NBO) and atoms in molecules(AIM) analyses have been performed to reveal the origin of interactions.To our interest,the result indicates that the strongest interaction is up to -22.34 kJ/mol after basis set superposition error(BSSE) and zero point energy(ZPE) correction at the MP2/6-311++G** level.Furthermore,the intermolecular interactions between aza-calix[2]arene[2]-triazines with the substituted amidos and RDX are stronger than those of other complexes.Thus,the complexes with amidos can be used as the candidates to increase the stability of explosive and eliminate the explosive wastewater.     

Lewis acid induced [4+3] cycloadditions of 2-silyloxyacroleins. Insights on the mechanism from a DFT analysis

The mechanism for the Lewis acid induced [4+3] cycloadditions of 2-(trimethylsilyloxy)acrolein with furan has been examined here through DFT calculations at B3LYP/6-31G* level. The mechanism is a three-step process initialized by the nucleophilic attack of furan to the β-conjugated position of acrolein yielding a zwitterionic intermediate. The key step on the formation of the seven-membered ring is the electrophilic attack of the furan residue to the carbonyl carbon in this intermediate. The endo selectivity experimentally observed is reproduced by the calculations.     

Effect of fluorine substitution in calix[4]pyrrole: A DFT study

Using density functional theory we investigate the ground-state geometries and electronic structures of calix[4]pyrrole (C4P) and its fluorine analogue (F-C4P). The HOMO–LUMO energy gap of C4P is 5.9 eV and remains nearly the same upon H-by-F replacement (5.7 eV). Fluorine substitution increases both the vertical and adiabatic ionization potentials of C4P by 0.8 eV while the electron affinity of either macrocycle is negative thus indicating that the corresponding radical anion in the gas-phase is thermodynamically unstable. It is shown that the topology of the LUMOs of both C4P and F-C4P have important implications for the spherical recognition of halide anions. The simulated IR, NMR, and electronic spectra display important fingerprints for the characterization of these macrocycles.     

新型间苯二酚杯芳烃硫脲衍生物对阴离子的识别

通过间苯二酚杯芳烃连续三步反应, 以较高产率合成了分子中连有8个和12个硫脲端基的间苯二酚杯芳烃的酰胺衍生物. 用紫外可见光谱法研究了两个代表性化合物4,6,10,12,16,18,22,24-八[6-(苯基硫脲基)-己氨甲酰基甲氧基]-2,8,14,20-四苯基杯[4]间苯二酚芳烃(THBC)和4,6,10,12,16,18,22,24-八[2-(苯基硫脲基)-1-甲基乙基-1-氨甲酰基甲氧基]-2,8,14,20-四苯基杯[4]间苯二酚芳烃(TPBC), 对各种阴离子(AcO^－, H₂PO₄^－, HSO₄^－, H₂PO₄^2－, C₁₂H₂₅-C₆H₄-SO₃^－, Cr₂O₇^2－, B₄O₇^2－, Cl^－, Br^－)的识别性能, 结果表明它们对AcO^－, H₂PO₄^－, HSO₄^－等阴离子有较好的配位作用, 能形成1∶3的配合物.     

Improved Synthesis of 9- and 10-Methylbenz[a] Anthracenes

The synthesis of 9- and 10-methylbenz[a]anthracenes by improved methods are described. These new procedures are simple and convenient, and provide the title compounds in good yields and high purity.     

Synthesis and self-assembly of novel calix[4]arenocrowns: formation of calix[4]areno[2]catenanes

A series of novel calix[4]arenocrowns 1a-c were efficiently synthesized by a one-pot reaction of calix[4]monohydroquinone diacetate 5 with ditosylate 6 and its analogues in the presence of sodium hydroxide. It was found that the calix[4]arenocrowns could form stable pseudorotaxane-type complexes 2a-c with paraquat, and further self-assemble into calix[4]areno[2]catenanes 3a-c with dicationic salt 8 and p-bis(bromomethyl)benzene.     

Characterization of a Redox-responsive Molecular Switch Based on Dibenzo[1,2]dithiine Using DFT

Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine (PSBH) were studied using the DFT-B3LYP/6-31G* method. The results confirmed that the electrical conductivity of the closed form of considered molecular switch is higher than that of the open form. NBO electric charges on heavy atoms of biphenyl unit revealed that the positive charge on sulfur atoms reinforced, which caused the collapse of disulfide bond.     

[60]富勒烯[2＋2]环加成反应的研究进展

[2＋2]环加成反应是对C₆₀进行化学修饰的重要反应之一, 重点从[2＋2]环加成的典型反应、主要试剂及反应机理等方面进行了综述.