A comparison of pressure induced and concentration induced smectic A-nematic-isotropic triple points

Optical microscopy in mixtures of di-octylazoxybenzene (8AB) and di-nonylazoxybenzene (9AB) reveals that a smectic A-nematic-isotropic triple point occurs at 71·5±0·5°C and 38±2wt% 8AB. Although this concentration induced triple point is different from the pressure induced triple point known to exist in pure 9AB at elevated pressure, analysis of the data from both the mixing and pressure experiments reveals that the phase transition surfaces in temperature-pressure-concentration space for this system are nearly planar.     

Syntheses,structures, and luminescence of two Zn(II) coordination polymers based on 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole and carboxylates

Reactions of Zn(II) salts, 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and 2-mercaptobenzoic acid or 2-propyl-1H-imidazole-4,5-dicarboxylic acid (H₃PrIDC), result in two mixed-ligand coordination polymers (CPs), [Zn₂(IPT)(DSDB)(OH)]_n (H₂DSDB = 2,2′-disulfanediyldibenzoic acid, 1) and [Zn₂(IPT)(PrIDC)(H₂O)]_n (H₃PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, 2). Compound 1 possesses a 2-D structure built by 1-D [Zn(IPT)]_n chains and DSDB^2? connectors, in which the DSDB^2? is generated via in situ reaction from 2-mercaptobenzoic acid. It displays a new intricate 4-nodal {3·4·6·7·8·9}{3·6·7·8·9·10}{3·8·9}{4·6·8} topology. Compound 2 displays a 3-D framework with new 3-connected topology with Schläfli symbol of (4·8·10) (8·12²), in which the 1-D Zn-carboxylate chains were bridged by 3-connected IPT^? ligands. The thermal stabilities and luminescence properties of 1 and 2 have also been studied. The compounds exhibit intense solid-state fluorescent emissions at room temperature.     

1,2-oxazine chemistry—IV : The conformational equilibria in 2,5- and 2,4-dimethyltetrahydro-1,2-oxazines

The synthesis of 2,5-dimethyltetrahydro-1,2-oxazine via 5-methyldihydro-1,2-oxazine and the preparation of a pure sample of 2,4-dimethyltetrahydro-1,2-oxazine are reported. For the 2,5-dimethyl derivative low temperature (?40° to ?45°) ¹H NMR measurements show signals from the trans (95%) and cis (5%) conformations. From this result it follows that an axial 5-Me group in a tetrahydro-1,2-oxazine ring is 5·7 ± 0·4 kJ mole^?1 less stable than when equatorial. Low temperature measurements on the 2,4-dimethyl derivative fail to show any sign of the conformation with an axial Me group. These results in conjunction with earlier relative free energy difference measurements, give the following conformational free energy differences for Me groups on ring C atoms; C(4) 7·1 ± 1·0; C(3) 7·9 ± 0·8; C(6) 10·1 ± 1·6 kJ mole^?1.     

A NMR study of trimethylacetic acid self-association

The carboxyl proton chemical shifts of neat trimethylacetic acid and its solutions in cyclohexane have been measured as a function of temperature. Formation, at the melting point, of a carboxyl group satellite line on the low field side has been found. The intensity of this satellite line rises with decreasing temperature, whereas the intensity of the main line decreases. The chemical shifts of the monomer (δ_m = 4·9 ± 0·6 ppm) and dimers, the equilibrium constants, enthalpy (ΔH = ?(11·3 ± 0·6) kcal/mol) and entropy (ΔS = ?(13·5 ± 0·7) cal/mol. degree) changes have been calculated using the concentration dependence of the chemical shifts of trimethylacetic acid in cyclohexane solutions at various temperatures. The chemical shift of the satellite line has been shown to correspond to the chemical shift of the cyclic dimers of the acid.     

刚性双(三氮唑)和羧酸混合配体构建的两种金属有机骨架材料及其在CO2环加成反应中的催化性质

通过酸碱混合配体策略合成了 2 例含刚性双三氮唑配体的金属有机骨架(MOF)材料：{[Zn₂(L)(TP)₂(H₂O)·H₂O]}_n (1)和[Zn(L)(HTMA)]_n (2),其中L=4,4''-(3,3''-dimethyl-(1,1''-biphenyl)-4,4''-diyl)bis(4H-1,2,4-triazole),H₂TP=对苯二甲酸,H₃TMA=1,3,5-均苯三甲酸。用单晶 X 射线衍射表征其结构。结构分析表明,MOF 1显示出 3,6-双节点的二维结构,其拓扑符号为(4²·6)₂(4⁸·6⁶·8),MOF 2呈现为经典的 sql二维拓扑结构。在温和条件下,2对 CO₂与环氧化物的环加成反应具有优异的催化活性,且重复使用至少3次后仍然保持其催化性能。     

刚性双(三氮唑)和羧酸混合配体构建的两种金属有机骨架材料及其在CO2环加成反应中的催化性质

通过酸碱混合配体策略合成了 2 例含刚性双三氮唑配体的金属有机骨架(MOF)材料：{[Zn₂(L)(TP)₂(H₂O)·H₂O]}_n (1)和[Zn(L)(HTMA)]_n (2),其中L=4,4''-(3,3''-dimethyl-(1,1''-biphenyl)-4,4''-diyl)bis(4H-1,2,4-triazole),H₂TP=对苯二甲酸,H₃TMA=1,3,5-均苯三甲酸。用单晶 X 射线衍射表征其结构。结构分析表明,MOF 1显示出 3,6-双节点的二维结构,其拓扑符号为(4²·6)2(4⁸·6⁶·8),MOF 2呈现为经典的 sql二维拓扑结构。在温和条件下,2对 CO₂与环氧化物的环加成反应具有优异的催化活性,且重复使用至少3次后仍然保持其催化性能。     

两个三维柱层式单一手性配位化合物:合成、结构和性质（英文）

在溶剂热合成条件下得到2个单一手性配位聚合物,即[Cd3((R)-CIA)2(bipy)2.5(H2O)2]·xGuest(1)和[Zn3((R)-CIA)(bmib)2(H2O)2 Cl]·H2O·xGuest(2)((R)-H3CIA=(R)-5-(1-羧基乙氧基)间苯二甲酸,bipy=4,4′-联吡啶,bmib=1,4-双(2-甲基-1H-咪唑-1-基)苯)。X射线单晶结构分析揭示配合物1和2都是柱层式结构的三维框架。从拓扑分析的角度看,配位物1具有(3,3,3,6,6)-连接的网络,拓扑符号为(4.5^2)2(4.8^2)2(42.6^8.8^3.10^2)(4^2.6^8.8^3.9^2)(5.8.9)2,而配合物2是(3,4,4)-连接的网络,拓扑符号为(6·7^2)2(6·7^5)2(6^2·7^4)。此外,对上述配合物的热稳定性、圆二色谱和荧光性质也做了研究。     

Detonation Properties of High Explosives Containing Ammonia Borane

Ammonia borane (AB) is used as a combustion agent to improve the properties of high explosives. The detonation velocity (D_v) and detonation pressure (P) of raw high explosives and of samples containing AB were calculated and compared. The detonation properties, impact sensitivities, thermal sensitivities, and thermal decomposition characteristics of high explosives containing AB were also measured. The results indicated that when the AB content was 20 wt‐%, the optimal detonation velocity and detonation pressure were achieved. Both the detonation velocity and detonation pressure of the high explosives containing AB were clearly increased compared with those of the raw high explosives. Moreover, the detonation velocities of high explosives containing AB were 7078 to 7423 m · s^–1 and their density ranged from 1.570 to 1.589 g · cm^–3. The detonation pressure ranged from 34.5 to 37 GPa and the average heat of detonation was 6688 J · g^–1. Furthermore, the impact and thermal sensitivities were 170 cm and 613 K, respectively, whereas a slight change occurred in the thermal decomposition characteristics. These results suggest that AB can serve as a powerful combustible agent in energetic materials and improve the detonation properties and sensitivities of high explosives.     

Synthesis,crystal structure,and luminescence of a new zinc(II) coordination polymer based on 2-naphthol-5-carboxylate and 4,4′-bipyridine

To further explore the coordination possibilities of naphthalene-based carboxylic acids, a Zn^II coordination polymer, [Zn₃(L)₆(bipy)₂] _n (1), with bulky 2-naphthol-5-carboxylate (L) and bridging 4,4′-bipyridine (bipy), was synthesized and characterized. Structural analysis reveals that 1 is a 1-D polymeric chain with trinuclear units as nodes, which are further extended via interchain secondary interactions, such as O–H ··· O hydrogen-bonding and aromatic π ··· π stacking interactions, to form an overall 3-D framework. Complex 1 exhibits strong solid-state luminescence emission at room temperature, mainly originating from intraligand π→π* transition of L.     

基于3，4'，5-联苯三羧酸构筑的钕配合物的合成、结构、荧光、光催化及磁性质

采用NdCl₃·6H₂O和3,4'',5-联苯三羧酸（H₃bpt）为原料在DMF/H₂O混合溶剂热条件下合成得到一个三维钕配合物{[Nd （bpt）（DMF）（H₂O）]·2H₂O}_n（1）,并通过红外光谱、元素分析、单晶及粉末X射线衍射表征了配合物1的结构。单晶衍射结果表明,配合物1具有（5,5）-连接的三维结构,拓扑符号为（4⁴·6³·8³）（4⁸ 6²）。此外,对配合物1的热稳定性、荧光性质、光催化降解染料及磁性质进行了详细研究。     

Syntheses,urease inhibition activities,and fluorescent properties of transition metal complexes

Four transition metal complexes with Schiff base and 1,10-phenanthroline, [Cu(L)(phen)]₂·C₂H₅OH (1), [Zn(L)(phen)]₂·C₂H₅OH (2), [Ni(L)(phen)]₂·C₂H₅OH (3), and [Co(L)(phen)]₂·C₂H₅OH (4) (H₂L?=?1-((2-hydroxynaphthalen-1-yl)methylene)thiosemicarbazide; phen?=?1,10-phenanthroline) were synthesized and characterized by physico-chemical methods. The crystal structure of 1 was determined by X-ray single-crystal diffraction analysis. 1 crystallizes in the orthorhombic space group Pbca with a?=?15.008(9), b?=?16.100(10), c?=?37.54(2)?Å, V?=?9070(10)?ų, Z?=?8, GOOF?=?1.002, R ₁?=?0.0626, and wR ₂?=?0.0912. The fluorescence and urease inhibitory activities of the compounds were tested. The enzymatic activity study indicated that 3 possessed potent inhibition against jack bean urease, with IC₅₀?=?1.2?±?0.1?μM, and about 35 times more than 42.1?±?0.4 acetohydroxamic acid as positive reference. This suggests that inhibitory efficiency of these complexes can be strongly influenced by different transition metal ions.     

Thermal degradation and oxidation of polystyrene studied by factor-jump thermogravimetry

Factor-jump thermogravimetry has been used to study the activation energy of polystyrene degrading in a vacuum, in N₂ flowing at 4 mm/s and in $\text{N}{}_2\text{O}{}_2$ mixtures. The results show the activation energy to be 44·9 ± 0·2 kcal/mole (188 ± 0·8 kJ/mole) for degradation above 350°C in vacuum or in flowing N₂. This agrees well with work reported in 1949 by Jellinek⁷ but with few results reported subsequently.The apparent activation energy for polystyrene losing weight above 280°C in an atmosphere of abundant O₂ is 21·5 ± 0·2 kcal/mole (90·2 ± 0·8 kJ/mole). In all cases where O₂ was deliberately introduced (partial pressures >4 mm Hg), the sample degraded to a black tar and the activation energy was ≤30 kcal/mole, depending on the amount of oxygen present and on the thermal history of the sample.     

Synthesis,X-ray crystal structure,thermal and solution studies of a centrosymmetric metal–organic polymer based on proton transfer methodology

A 3-D metal–organic coordination polymer based on pyrazine-2,3-dicarboxylic acid (pzdcH₂) formulated as {[Mn(pzdc)(H₂O)₂] · 2H₂O} _n (1), was obtained by the treatment of MnCl₂ · 6H₂O with pzdcH₂, 8-hydroxy quinoline (8-HQ), and 2-amino-4-methyl pyridine (ampy). In this study, we describe the synthesis, elemental analysis, IR spectroscopy, TG analysis, and single X-ray diffraction. The X-ray single crystal structure reveals that the chemical environment around each Mn(II) is a distorted octahedral by participating one nitrogen, five oxygens from three (pzdc)^2? and two water molecules, O₅MnN. The centrosymmetric 1-D ladder-like structure of 1 is bridged by oxygens of (pzdc)^2?, and Mn–pzdc–Mn bonds are the rungs for our ladder structure. In the crystal structure, intermolecular O–H ··· O hydrogen bonds result in the formation of a supramolecular structure, effective for the stabilization of the structure. The thermal decomposition of 1 indicates that it is quite thermally stable. The protonation constants of ampy, 8-HQ and pzdcH₂ as the building blocks of proton transfer systems including pzdcH₂-ampy and pzdcH₂-8-HQ and the corresponding stability constants of these systems were determined by potentiometric study. The stoichiometry and stability constants of complexes of pzdcH₂-ampy and pzdcH₂-8-HQ with Mn²⁺ were investigated by this method in aqueous solution. The results obtained from solution study are comparable with the solid state results.     

篮子型有机膦酸锰簇合物：合成、晶体结构与磁性质研究

本文报道了1个新的有机膦酸锰簇合物[Mn₅O₃(C₁₁H₉PO₃)₂(PhCOO)₅(phen)₂]·2H₂O (1)的合成、结构及磁性质。单晶结构分析显示化合物1含有[Mn₅O₃]⁹⁺核结构,该结构通过连接5个金属离子形成了篮子型簇结构。化合物1的直流磁化率测试表明金属离子之间存在反铁磁相互作用。交流磁化率测试没有发现实部和虚部出现频率依赖行为,说明化合物1不是一个单分子磁体。     

Measurement of alpha-decay constant to fission cross section ratio for actinides using solid state nuclear track detectors

A simple technique based on the measurement of the ratio of alpha-decay constant to neutron induced fission cross section for pure actinides using solid state nuclear track detectors (SSNTDs) is developed for the identification of the actinides in trace levels in pure solutions. The alpha-decay constant to fission cross section ratios for depleted U,²³⁸Pu and²⁴⁰Pu have been measured for the epicadmium neutron induced fission of these actinides. The measured values are (6.19±0.34)·10⁶, (6.95±0.26)·10¹², (2.12±0.95)·10⁹ and (2.18±1.58)·10¹¹ sec⁻¹·cm⁻², respectively. These ratios can be used for the trace level identification of pure actinides.     

Zur frage transanularer II-II-wechselwirkungen im [2.2]metacyclophan, [2.2]Paracyclophan und 2,2′-spirobiindan

Concerning the question of transanular II-II-interactions in [2.2]metacyclophane, [2.2]paracyclophane and 2,2′-spirobiindane.From the quotient of the two dissociation constants (K₁/K₂) of [2.2]metacyclophane-bis-chromtricarbonyl (9·0 ± 1·9) it was concluded that there are no transanular II-II-interactions between the two benzene rings. The corresponding values for the bis-chromtricarbonyl-complexes of 2,2′-spirobiindane and [2.2]paracyclophane are 8·0 ± 1·5 and 10⁴, resp. These results are supported by IR-spectroscopical data of the CO-frequencies of the Cr(CO)₃-complexes of [2.2]metacyclophane and some derivatives, of 2,2′-spirobiindane and [2.2]paracyclophane.Moreover, UV-spectroscopic studies of tetracyanoethylene complexes of arenes are shown to be insignificant with regard to transanular II-II-interactions.     

基于双(4-(1H-咪唑-1-基)苯基)甲酮的三个锌配位聚合物的结构多样性和发光性质

通过溶剂热法合成了 3 个锌的配位聚合物{[Zn₂(bipmo)₂(ipa)₂]·3H₂O}_n (1)、{[Zn(bipmo)(5-OH-ipa)]·DMA·H₂O}_n (2)和{[Zn(bipmo)(5-Me-ipa)]·H₂O}_n (3),其中 bipmo=双(4-(1H-咪唑-1-基)苯基)甲酮,H₂ipa=间苯二甲酸,5-OH-ipaH₂=5-羟基间苯二甲酸,5-Me-ipaH₂=5-甲基间苯二甲酸。用元素分析、红外光谱和单晶X射线衍射等技术对结构进行了表征。单晶X射线衍射分析表明,配合物1具有二重互穿的{4⁴·6²}二维网络结构,配合物2则是{6⁵·8}拓扑的二维结构,配合物3却表现为二维的{6³}拓扑网络。间苯二甲酸上 5-位取代基的不同对最终的结构形成有重要的影响。此外,对化合物 1~3的发光性质也进行了详细研究。     

The oxidation of methyl radicals at room temperature

Using the technique of molecular modulation spectrometry, we have measured directly the rate constants of several reactions involved in the oxidation of methyl radicals at room temperature: k₁ is in the fall-off pressure regime at our experimental pressures (20–760 torr) where the order lies between second and third and we obtain an estimate for the second-orderlimit of (1.2 ± 0.6) × 10^?12 cm³/molec · sec, together with third-order rate constants of (3.1 ± 0.8) × 10^?31 cm⁶/molec² · sec with N₂ as third body and (1.5 ± 0.8) × 10^?30 with neopentane; we cannot differentiate between k_2a and k_2c and we conclude k_2a + (k_2c) = (3.05 ± 0.8) × 10^?13 cm³/molec · sec and k_2b = (1.6 ± 0.4) × 10^?13 cm³/molec · sec; k₃ = (6.0 ± 1.0) × 10^?11 cm³/molec · sec.     

基于双(4-(1H-咪唑-1-基)苯基)甲酮的三个锌配位聚合物的结构多样性和发光性质

通过溶剂热法合成了3个锌的配位聚合物{[Zn₂(bipmo)₂(ipa)₂]·3H₂O}_n(1)、{[Zn (bipmo)(5-OH-ipa)]·DMA·H₂O}_n(2)和{[Zn (bipmo)(5-Me-ipa)]·H₂O}_n(3),其中bipmo=双(4-(1H-咪唑-1-基)苯基)甲酮,H₂ipa=间苯二甲酸,5-OH-ipaH₂=5-羟基间苯二甲酸,5-Me-ipaH₂=5-甲基间苯二甲酸。用元素分析、红外光谱和单晶X射线衍射等技术对结构进行了表征。单晶X射线衍射分析表明,配合物1具有二重互穿的{4⁴·6²}二维网络结构,配合物2则是{6⁵·8}拓扑的二维结构,配合物3却表现为二维的{6³}拓扑网络。间苯二甲酸上5-位取代基的不同对最终的结构形成有重要的影响。此外,对化合物1~3的发光性质也进行了详细研究。     

RE(C5H8NS2)3(C12H8N2)的标准摩尔生成焓

在无水乙醇中, 使低水合氯化稀土 (RE = Ho, Er, Tm, Yb, Lu) 与吡咯烷二硫代氨基甲酸铵 (APDC)和1,10-菲咯啉 (o–phen•H₂O) 反应, 制得其三元固态配合物. 用化学分析和元素分析确定它的组成为RE(C₅H₈NS₂)₃(C₁₂H₈N₂) (RE = Ho, Er, Tm, Yb, Lu). IR光谱说明RE³⁺ 分别与3个PDC^–的6个硫原子双齿配位, 同时与o–phen的2个氮原子双齿配位, 配位数为8. 用精密转动弹热量计测定了它们的恒容燃烧热△_cU分别为(-16788.46 ± 7.74), (-15434.53 ± 8.28), (-15287.80 ± 7.31), (-15200.50 ± 7.22)和(-15254.34 ± 6.61) kJ•mol^-1; 并计算了它们的标准摩尔燃烧焓△_cH_m^θ和标准摩尔生成焓△_fH_m^θ分别为( -16803.95 ± 7.74), (-15450.02 ± 8.28), (-15303.29 ± 9.28), (-15215.99 ± 7.22), (-15269.83 ± 6.61) kJ • mol^-1和 (-1115.42 ± 8.94), (-2477.80 ± 9.15), (-2619.95 ± 10.44), (-2670.17 ± 8.22), (-2650.06 ± 8.49) kJ•mol^-1.