吡啶氮桥联三唑卡宾反应性质及其Pd(Ⅱ)-配合物催化杂芳环与芳基溴的α-烷基化反应研究

报道了吡啶氮桥联的双环三唑鎓盐1在NaH,K2CO3为碱的条件下脱去质子,分别形成三唑卡宾2和吡啶氮桥联三唑卡宾二聚体4,研究了2和4与亲电试剂的反应性质,2与水的反应产物Ⅳ-乙基-N'-吡啶基甲醛肼3经单晶衍射结构分析.考察了配体1的卡宾-Pd(Ⅱ)配合物催化咖啡因与芳基溴的α-芳基化反应,在优化催化反应条件下,比较了不同三唑鎓盐之间的催化活性.结果表明,三唑鎓盐1表现出优良的催化活性.     

无铜参与的钯催化Sonogashira偶联反应合成β-(2-苯乙炔基)环丁酮类化合物

本文发展了一种简单高效的单钯催化体系,用于β-(2-溴芳基)环丁酮和末端炔的Sonogashira反应中,合成了一系列邻炔芳基-β-环丁酮类化合物.反应条件简单温和,催化剂及配体稳定易得,实验操作简捷便利,底物普适性良好.实现了金催化剂引发的该环丁酮类化合物的扩环反应.     

由二茂铁亚胺环钯催化的Suzuki偶联反应合成具有发光性能的3-芳基噻吩

3-芳基取代噻吩大多是电致发光材料的前体化合物. 催化剂摩尔分数为0.5% 的二茂铁亚胺环钯化合物在DMF/K3PO4/80 ℃条件下, 能够有效地催化3-噻吩硼酸同芳基碘和芳基溴的Suzuki反应, 方便地合成系列3-芳基噻吩衍生物. 此方法操作简便, 不需要加入过量的3-噻吩硼酸, 催化剂用量小. 化合物3b, 3c和3d的发射光谱和激发光谱表明, 此类化合物具有潜在的发光应用性能.     

三联吡啶铁配位聚合物电致变色材料的合成及性能

将芳环作为桥联基团引入到2个三联吡啶单元之间构建多齿配体,与四氟硼酸亚铁六水合物配位,制备了一类新型的三联吡啶铁配位聚合物,并研究了其在水系电解液中的电致变色性能。研究结果表明,芳环上氟原子的引入对材料电致变色性能具有一定的影响。其中,采用含有2个氟原子的配体F2制备的铁配位聚合物Fe-F2表现出优异的电致变色性能（光学对比度高达69%,响应时间短至0.5 s,着色效率超过320 cm²·C^-1）。     

三联吡啶铁配位聚合物电致变色材料的合成及性能

将芳环作为桥联基团引入到2个三联吡啶单元之间构建多齿配体，与四氟硼酸亚铁六水合物配位，制备了一类新型的三联吡啶铁配位聚合物，并研究了其在水系电解液中的电致变色性能。研究结果表明，芳环上氟原子的引入对材料电致变色性能具有一定的影响。其中，采用含有2个氟原子的配体F2制备的铁配位聚合物Fe-F2表现出优异的电致变色性能(光学对比度高达69%，响应时间短至0.5 s，着色效率超过320 cm²·C^-1)。     

3-杂环基硫取代-1,3,4,5-四氢-2-氧代-苯并氮杂衍生物的合成

以芳酰肼为原料,合成了一系列3-巯基-5-芳基-1,2,4-三唑、2-巯基-5-芳基-1,3,4-噁二唑和2-巯基-5-芳基-1,3,4-噻二唑,并通过硫原子对3-溴-2-氧代-苯并氮杂3-位上的亲核取代反应将杂环化合物引入了苯并氮杂的结构当中,合成了32个新的苯并氮杂杂环衍生物.为提高其在有机溶剂中的溶解性,在苯并氮杂的N原子上引入乙酸乙酯和乙酸叔丁酯基取代基,合成了36个新衍生物.所有化合物经质谱、核磁共振谱及元素分析确证了结构并初步测定了抗菌活性.     

侧向多氟取代二芳基乙炔类液晶的合成及性能

以对烷基溴苯和4-溴-2,3-二氟苯酚为原料,经芳基硼酸化、Suzuki偶联反应、Sonogashira偶联反应和碘代等反应,制得16种侧向多氟取代二芳基乙炔类液晶化合物,其结构经IR、NMR和MS确认。利用差示扫描量热仪(DSC)、偏光显微镜(POM)和阿贝折光仪对该系列化合物进行了性能研究。结果表明,该系列化合物具有较低的熔点、宽的液晶相区以及较高的光学各向异性值(Δn>0.3)。该类液晶具有在双频液晶中应用的广阔前景。     

3-杂环基硫取代-1,3,4,5-四氢-2-氧代-苯并氮杂衍生物的合成

以芳酰肼为原料, 合成了一系列3-巯基-5-芳基-1,2,4-三唑、2-巯基-5-芳基-1,3,4-噁二唑和2-巯基-5-芳 基-1,3,4-噻二唑, 并通过硫原子对3-溴-2-氧代-苯并氮杂3-位上的亲核取代反应将杂环化合物引入了苯并氮杂的结构当中, 合成了32个新的苯并氮杂杂环衍生物. 为提高其在有机溶剂中的溶解性, 在苯并氮杂的N原子上引入乙酸乙酯和乙酸叔丁酯基取代基, 合成了36个新衍生物. 所有化合物经质谱、核磁共振谱及元素分析确证了结构并初步测定了抗菌活性.     

4-(2,2-二溴代乙烯基)二芳基醚的合成及应用

以酚类化合物和4-溴苯甲醛为原料,通过铜催化的Ullmann类型反应和Corey-Fuchs两步反应,高收率地合成了一组4-(2,2-二溴代乙烯基)二芳基醚(含偕二溴乙烯基的二芳醚)类化合物。实验表明,该类化合物可发生消除反应转化为4-乙炔基二芳基醚,并通过和苄基叠氮之间的铜催化[3+2]环加成反应,进一步制备含三氮唑官能团的二芳基醚类化合物。     

新型蓝光材料: 氟代三联(9,9-二苯基)芴的合成及其光电性能研究

使用HF/吡啶法在芴环的4位引入了氟原子, 使用五氟氯苯格氏试剂在芴环的9位引入了全氟苯, 合成了五个氟取代三联(9,9-二苯基)芴化合物. 测量了该系列化合物的电化学、光学和电致发光性能, 氟原子的引入提高了化合物的电子传输能力. 在溶液和薄膜状态下, 该类化合物都呈现出稳定的蓝光发射(色坐标x＝0.156, y＝0.078). 由化合物6f制备的简单器件的启亮电压为6 V, 最大亮度为452 cd/m2.     

Theoretical study of structures and properties of cyclobutadiene, cyclopentadiene and benzene and their nitrogen isoelectronic equivalents

B3LYP/aug-cc-pvDZ level of theory is applied to study the geometric structures, electronic topologies, heats of formation, hyperconjugations and steric repulsions of 27 kinds of compounds obtained by successive replacement of CH groups with nitrogen atoms in cyclobutadiene, cyclopentadiene and benzene. The results reveal that the total energy linearly decreases along with the replacement of CH groups by nitrogen atoms for the three systems. To estimate the potential of high nitrogen content high energy materials (HNC–HEMs), heats of formation are calculated by G3 method. With the increase of the number of nitrogen atoms in ring, heats of formation increase substantially. The four-membered ring system is found to have the greatest heat of formations, followed by the six-membered ring system, and then by the five-membered ring system. Especially, hexazine and tetraazacyclobutadiene have great heats of formation relative to the other compounds, which implies that they should be applicable as HNC–HEMs. In addition, our studies indicate that the relationship between the total energy or heats of formation of isomers and the position of nitrogen atoms is (ortho) meta < (ortho) para < ortho. NBO analysis shows that it is hyperconjugation, not steric repulsion that plays a key role in the relative stability of isomers.     

Liquid Crystalline Thiadiazole Derivatives: Thiadiazole Derivatives Containing Pyridine Ring as Terminal Group

The synthesis and mesomorphic behavior of a new series of liquid crystals containing 1, 3, 4‐thiadiazole and pyridine rings with ‐CH = N‐ central group are reported. All compounds exhibit enantiotropic smectic A mesophase, but the Schiff's base analogues have no mesomorphic behavior. The influence of the pyridine ring and thiadiazole ring is discussed.     

Synthesis of cyclopentyloxy terphenyl liquid crystals with negative dielectric anisotropy

Liquid crystalline materials possessing negative dielectric anisotropy (Δε) have attracted considerable attention because they can be used to formulate eutectic mixture for several display applications. The negative Δε can be achieved by introducing a lateral polar substituent onto the mesogen core of a liquid crystalline material, and fluorine atoms are usually used because of the small size and high electronegativity. 2,3-ortho-Difluoro substituent liquid crystals exhibit stable and profound physical properties such as the low viscosity, strong negative Δε, and high solubility. To avoid the decrease of the mesophase range, 2,3-ortho-difluorophenyl is often placed next to the terminal chain. In this paper, we have synthesised a new series of 2,3-ortho-difluoroterphenyl liquid crystals with a negative dielectric anisotropy. Ether oxygen is introduced to the structure because it can further increase the lateral dipole moment. 3-Alkylcyclopentane end group decreases both the melting point and the viscosity, which makes it an appropriate substituent for negative Δε 2,3-ortho-difluoroterphenyl liquid crystals. The mesomorphic properties as well as the optical anisotropies of the synthesised liquid crystals are discussed in this paper. All compounds in the series are found to possess highly negative dielectric anisotropy, wide mesophase ranges; therefore, they have a great potential to formulate eutectic mixture for liquid crystal displays.     

New mesogenic 1,3,4-oxadiazole derivatives

The synthesis of novel liquid-crystalline heteroaromatic compounds incorporating the five membered 1,3,4-oxadiazole ring is described. Due to the bent molecular structure of the oxadiazole ring their mesophase stability is low if the heterocyclic ring occupies a central position, but it is increased if this ring is shifted to a terminal position. Dielectric measurements indicate that the 2-n-alkylthio substitutes 1,3,4-oxadiazole derivatives change the sign of the dielectric anisotropy at the phase transition from the nematic to the smectic A phase. This effect is explained by the increase of the antiparallel correlation of the molecules on formation of the smectic layers.     

The 1H NMR spectra of zinc complexes of pyridine-2-carbaldehyde 2′-pyridylhydrazone

Proton magnetic resonance spectra at 100 MHz are described for some zinc complexes of the E- and Z-isomers of pyridine-2-carbaldehyde 2′-pyridylhydrazone in d₆-dimethylsulphoxide solution. Chemical shift data are discussed qualitatively in relation to factors such as the charge on the metal ion, the anisotropy of ligand nitrogen atoms, electric field effects caused by the dipole moment of nitrogen lone pairs, metal-nonbonded-hydrogen interactions, ring current effects and the conformational changes undergone by each isomer on coordination.     

Competitive formation of condensed azines and dihydropyridines in the reaction of ethyl 3,3-diaminoacrylate with <Emphasis Type="Italic">o</Emphasis>-halo carbaldehydes

The reaction of ethyl 3,3-diaminoacrylate with quinoline-3-carbaldehydes and 3-nitrobenzaldehydes to give a dihydropyridine and condensed azine has been studied with respect to the number and reactivity of the halogen atoms in an ortho position to the formyl groups. For the series of quinoline-3-carbaldehydes it was found that the reaction course is determined by the number of chlorine atoms. 2-and 4-Chloroquinoline-3-carbaldehydes give dihydropyridines and a benzo[c][2,7-]naphthyridine is formed in the reaction with 2,4-dichloroquinoline-3-carbaldehyde. The main products in the case of nitrobenzaldehydes are dihydropyridines which points the deciding influence of the low electrophilicity of aromatic ring. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 567–577, April, 2008.     

Synthesis, mesomorphic properties and structural study by semi-empirical calculations of amides containing the 1,3,4-thiadiazole unit

The synthesis and liquid crystalline properties of a new series of amides (series 2a-f , 3a-d and 4a-d ) incorporating pyridine and 1,3,4-thiadiazole rings are reported. No homologues of the series 2 show mesomorphic properties. In the series 3 only the highest homologues ( 3d ) displays an enantiotropic SmA mesophase; the compound 3c exhibits a monotropic SmA mesophase, and the homologues 3a , b display no liquid crystal properties. The amides 4b-d display an enantiotropic SmA phases and the first homologue ( 4a ) exhibit only crystalisotropic transition. These series are compared with previously reported Schiff's bases and amide analogues. A structural study by AM1 semi-empirical calculation is also described.     

Synthesis,Crystal Structures,and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ₂‐pyrazine‐N,N) zinc(II) ( 1 ) and bis(isothiocyanato‐N)‐bis(μ₂‐pyrimidine‐N,N) zinc(II) ( 2 ) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S ··· S interactions in 1 and by weak intermolecular C–H ··· S hydrogen bonding in 2 . In bis(isothiocyanato‐N)‐bis(pyridazine‐N) ( 3 ) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) ( 4 ) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1 , 2 , and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) ( 5 ) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.     

Crystal structure, electronic properties and cytotoxic activity of palladium chloride complexes with monosubstituted pyridines

Palladium(II) complexes attract great attention due to their remarkable catalytic and biological activity. In the present study X-ray characterization, UV-Vis and Time-Dependent Density Functional Theory (TD-DFT) calculations for six PdCl(2)(XPy)(2) complexes (where: Py = pyridine; X = H, CH(3) or Cl) were applied in order to investigate substituent effects on their crystal structures and electronic properties and to combine the results with their catalytic and cytotoxic activity. The structures of complexes PdCl(2)(3-MePy)(2), PdCl(2)(4-MePy)(2) and PdCl(2)(2-ClPy)(2), have been described for the first time and we compared our results with available data for the whole series of six complexes. All compounds exhibit a square planar coordination geometry in which the palladium ion coordinates two nitrogen atoms of pyridine ligands and two chlorine atoms in trans positions. For complexes with ortho substituted XPy ligands a cis disposition of substituents takes place, whereas for other ligands: 3-MePy and 3-ClPy--the substituents are in trans positions. For XPy the energies of π-π* and n-π* transitions depend on the position and nature of the X substituent in the XPy ring. After complex formation a hipsochromic shift (24-34 nm) of π-π* and a bathochromic shift of n-π* bands are observed. The UV-Vis spectra of PdCl(2)(XPy)(2) confirm that square planar coordination geometry of complexes I-VI and two dπ-π* transitions are expected. With the help of the TD-DFT calculations we proved that dπ-π* transitions in solutions of PdCl(2)(XPy)(2) complexes result from MLCT (metal-to-ligand charge transfer) with contribution from chlorine atoms to palladium. We also studied substituent effects on cytotoxic properties of Pd(II) complexes against the human breast cancer cell line MCF7, the human prostate cancer cell line PC3, and the human T-cell lymphoblast-like cell line CCRF. The studied complexes were the most active against the CCRF cell line and less or even no cytotoxic effect was observed for PC3 cells. Complexes with MePy ligands showed increased cytotoxic activity compared to unsubstituted pyridine ligands.     

Spectroscopic and magnetic properties of copper(II) complexes derived from pyridine-2-carbaldehyde thiosemicarbazone. Structures of [Cu(NO3)(C7H8N4S)(H2O)](NO3) and [{Cu(NCS)(C7H7N4S)}2]

Complexes with the formula CuX(L) (X=N₃ 1, NCO 2 and NCS 3) and [Cu(NO₃)(HL)(H₂O)](NO₃) 4, where HL=C₇H₈N₄S, (pyridine-2-carbaldehyde thiosemicarbazone), have been characterised. Single-crystal X-ray diffraction studies on compounds 3 and 4 have been carried out. The structure of compound 4 consists of monomeric distorted square pyramidal copper(II) species. The copper(II) ions are coordinated to the NNS atoms from the tridentate thiosemicarbazone ligand and one oxygen atom of a nitrate group in the equatorial position. The oxygen atom of the water molecule occupies the apical position. The structure of compound 3 consists of non-centrosymmetric {Cu₂(μ-SR)₂} entities in which the copper(II) ions exhibit five-coordinate square–pyramidal geometry. The thiosemicarbazone ligand and one nitrogen atom from the thiocyanate ion are in a basal position. The sulfur atom of the tridentate ligand acts as a bridge occupying the apical position. Structural and spectroscopic results suggest the presence of relevant σ ligand-to-metal charge transfer and metal-to-ligand π-backdonation character in these compounds. The ESR spectra of compounds 3 and 4 show rhombic symmetry. For complexes 1 and 2 the ESR spectra exhibit axial signals. Magnetic measurements on compounds 1, 2 and 3 show antiferromagnetic couplings. The susceptibility data were fitted by the Bleaney–Bowers’ equation for copper(II) dimers. The obtained J/k values are −4.22, −6.10 and −7.33 K for compounds 1, 2 and 3, respectively.