金属串配合物(n,m)[Cr3(PhPyF)4Cl2](n=2, 3, 4; m=2, 1, 0)的配位结构及其与电场的关系

应用密度泛函理论BP86 方法研究具有分子导线潜在应用的金属串配合物(n, m)[Cr₃(PhPyF)₄Cl₂](HPhPyF=N, N'-苯基吡啶基甲脒; n=2, 3, 4; m=2, 1, 0)的配位结构及其受电场作用的影响, n、m分别表示PhPyF-的苯环在左侧和在右侧的配体个数. 结果表明: (1) 零电场下, 四个PhPyF-的(2, 2)、(3, 1)和(4, 0)三种配位方式能量差别很小, 为竞争态, (2, 2)最稳定. (4, 0)结构中两端轴向配体Cl 均可与Cr 配位, 且Cl₄―Cr1 键比Cl5―Cr3键更强, 若作为分子器件可与电极结合, 这与(4, 0)[CuCuM(npa)₄Cl][PF₆](M=Pd, Pt; Hnpa=2-萘啶苯胺)靠近苯环一端的轴向配体无法与M配位不同. (2) 在(2, 2)、(3, 1)和(4, 0)中, Cr₃⁶⁺链均具有三中心三电子离域σ键, 但离域性逐渐减弱. 随四个PhPyF-配位方式趋于一致, 分子极性逐渐增大, 由Cl₄指向Cl5(Z)方向, Cr1的α自旋密度增大, Cr2 的β和Cr3 的α自旋密度减小. (3) 分子的几何结构和电子结构在电场下发生规律性变化, 在-Z方向电场作用下, (3, 1)、(4, 0)电子移动方向与极性方向相同, 使分子的键长、自旋密度、电荷和能隙变化显著性均大于Z方向电场, 且极性越大变化越显著, 有利于提高分子导电性.     

(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)簇结构及其热力学性质

用HF自洽场理论和密度泛函理论(DFT)的B3LYP方法,在6 31G水平上研究了低聚物(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)簇的几何构型、电子结构和聚合反应热力学性质,比较了两个系列化合物中化学键的强度.结果表明,Cl2AlNH2和H2AlNH2分子为C2 (EC)平面型结构,其中Al－N为由一个σ键和一个键组成的双键.(Cl2AlNH2)n和(H2AlNH2)n(n=1～5)分子为Dnh对称,Al－N是典型的σ单键 .低聚物(Cl2AlNH2)n和(H2AlNH2)n的稳定性顺序分别为: 3 > 2 > 4> 5 > 1和8 > 7 > 9 > 11 > 6.     

(Cl_2AlNH_2)_n和(H_2AlNH_2)_n(n=1～ 5)簇结构及其热力学性质

用 HF自洽场理论和密度泛函理论 (DFT)的 B3LYP方法 ,在 6 31G水平上研究了低聚物 (Cl2AlNH2)n和 (H2AlNH2)n(n=1～ 5)簇的几何构型、电子结构和聚合反应热力学性质 ,比较了两个系列化合物中化学键的强度 .结果表明 ,Cl2AlNH2和 H2AlNH2分子为 C2υ (EC)平面型结构 ,其中 Al－ N为由一个σ键和一个π键组成的双键 .(Cl2AlNH2)n和 (H2AlNH2)n(n=1～ 5)分子为 Dnh对称 ,Al－ N是典型的σ单键 .低聚物 (Cl2AlNH2)n和 (H2AlNH2)n的稳定性顺序分别为 : 3 > 2 > 4> 5 > 1和 8 > 7 > 9 > 11 > 6.     

2-苯基吡啶铱(Ⅲ)配合物及其衍生物光谱性质的理论研究

采用密度泛函理论B3PW91和UB3PW91方法, 分别对4种Ir(Ⅲ)配合物(ppy)₂Ir(acac)(1, ppy=2-苯基吡啶, acac=乙酰丙酮)、(npy)₂Ir(acac)(2, npy=2-萘-1-基吡啶)、(pq)₂Ir(acac)(3, pq=2-苯基喹啉)和(bzq)₂Ir(acac)(4, bzq=苯并喹啉)进行了基态和激发态的几何优化, 在此基础上用TD-DFT方法计算了吸收和发射光谱. 结果表明, 随着ppy配体上并苯环位置的变化, 参与最大吸收和发射的分子轨道能隙降低程度不同, 从而使配合物2, 3, 4的最大吸收和发射光谱都比配合物1发生红移, 其中在吡啶环上增加苯环对吸收光谱的影响最大. 这4个分子最大吸收波长的顺序为1<2<4<3, 而最大发射波长顺序则是1<4<3<2. 由于配合物2的两个苯环上H的强排斥作用降低了其共轭程度, 使分子发生很大程度的扭曲, 导致其斯托克位移最大.     

反-1,2-双[2'-(5'-苯基恶唑基)]乙烯的晶体结构

用X射线单晶衍射法测定了反-1,2-双[2'-(5'-苯基恶唑基)]乙烯(POEOP)的晶体结构,POEOP晶体属单斜晶系, 空间群为P2~1/C, a=0.8268(2), b=0.5977(2), c=1.6292(3)nm;β=100.55(2)°; v=0.7915nm~3; Z=2; d~x=1.319g/cm~3。POEOP分子具有中心对称性,它的两个苯环和两个恶唑环是彼此平行的, 但整个分子却稍有些扭曲成螺旋浆式构型。键长数据表明POEOP分子中苯环与恶唑环以及恶唑环与C'=C双键间均有很大程度共轭。     

多氯二苯硫醚结构参数和热力学性质的密度泛函理论研究

在B3LYP/6-31G*水平上对209个多氯二苯硫醚(PCDS)系列化合物进行了全优化计算, 得到各分子的结构参数和热力学参数. 研究了这些参数与氯原子在苯环各位置的取代数目和相互位置(N_PCS)之间的关系发现: 分子平均极化率(α)、焓(H $)、自由能(G $)、恒容热容( )和熵(S $)与N_PCS之间有很强的相关性, 相关性系数r²＞0.988, 分子体积(V_m)、最高占据轨道能(E_HOMO)和最低未占据轨道能(E_LUMO)与N_PCS也有较好的相关性, 相关性系数r²分别为0.949, 0.894和0.915. 设计等键反应, 计算了PCDS各异构体的标准生成热(Δ_fH $)和标准生成自由能(Δ_fG $). 根据异构体自由能的相对大小, 求得异构体的相对稳定性顺序.     

(Al16Ti)n± (n=0-3)离子团簇中Ti原子对电子结构及其与H2O分子相互作用的显著影响

用密度泛函理论结合全电子自旋极化方法构建并优化出了最稳定的(Al₁₆Ti)^n± (n=0-3)离子团簇, 研究了其几何结构、稳定性和电子结构. 同时研究了水分子在(Al₁₆Ti)^n± (n=0-3)离子团簇表面的吸附结构和吸附能. 研究结果与纯(Al₁₇Ti)^n± (n=0-3)离子团簇的电子结构及其与H₂O分子的相互作用规律做了对比. 通过电子最高占据轨道和最低空轨道的空间分布, 发现大部分的活性电子占据在Ti 原子位置, 少量电子根据曲率从大到小的顺序依次占据. 通过分析最稳定的(Al₁₆TiH₂O)^n± (n=0-3)吸附化合物的几何结构可以看出, 水分子都倾向于吸附在Ti原子上, 并且为亲氧吸附. 在所有的吸附化合物中, (Al₁₆TiH₂O)⁺具有最短的平均O―H键长, 比孤立H₂O分子中的O―H键约长0.0003 nm, 然后随着电子数的增加或减少, O―H键都会进一步被拉长. 研究结果表明, Al 团簇离子中Ti 原子的掺杂可以有效提高H₂O分子的解离效率. 另外, 在金属团簇的几何结构效应与杂质效应共同出现时, 杂质的影响占据了主导地位.     

一锅法合成2-羟基-9-芴酮类化合物

芴酮骨架的构建对于相关天然产物合成、药物分子结构修饰以及光电材料开发等具有重要意义。以苯环作为桥连基团,将呋喃环及炔酮片段构建在同一个分子内,设计并合成了邻呋喃芳基炔酮底物(1a)。利用化合物1a分子内呋喃环与炔键的D-A反应,在酸性条件下环氧开环,进而芳构化,一锅法得到了2-羟基-9-芴酮衍生物2a~2e,收率89%~96%,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。其中,化合物2a结构由X-ray单晶衍射确定。2a(CCDC: 2144829)属单斜晶系,空间群P2₁/c,晶胞参数a=3.94580(10) Å, b=22.4460(7) Å, c=14.7092(5) Å, V=1294.1300(7) ų, Dc=1.3980 Mg/m³, Z=4, F(000)=568。     

新颖的蛋白质格点模型

提出了建立在键长涨落模型基础上的蛋白质格点模型,通过对二维蛋白质分子的构象研究,发现这种蛋白质分子具有更多的紧密接触对、更低的基态能量和更大的平均紧密度.蛋白质分子的构象数与键数目N的关系为:Ω₀～γ^N,这里γ=4.768.同时与二维的正方形蛋白质格点模型进行了比较.     

3-苄氧羰基四氢噻唑-2-硫酮的晶体结构与量子化学研究

苄氧羰酰氯与四氢噻唑-2-硫酮在三乙胺存在下反应生成了3-苄氧羰基四氢噻唑-2-硫酮。在甲醇中培养了标题化合物单晶,用X射线衍射法进行了结构表征。晶体结构属三斜晶系,P1间群,晶体学参数:a=0.6274(2)nm,b=0.7340(3)nm,c=1.2976(4)nm;α=100.73(3)°,β=94.53(3)°,γ=103.28(3)°,Z=2,M_μ=4.30cm^-1.分子中的>C=O与>C=S基团处于C(4)-N-C(1)键的同侧,为顺式。用PM₃分子轨道方法研究了该化合物的电子结构,得到电荷和键序分布以及前线轨道等性质。     

Quantum chemical computations and Fourier transform infrared spectral studies of a nonlinear food dye E110

Fourier transform infrared (FTIR) spectrum of a well-known food dye sunset yellow FCF (E110) has been recorded and analysed. Assignments of the vibrational spectrum has been facilitated by density functional theory (DFT) calculations. The results of the optimized molecular structure obtained on the basis of B3LYP with 6-31G(d) along with the 'LANL2DZ' basis sets give clear evidence for the intramolecular charge transfer (ICT) and strong hydrogen bonding enhancing the optical nonlinearity of the molecule. The first hyperpolarizability of the acidic monoazo dye 'E110' is computed. Azo stretching frequencies have been lowered due to conjugation and pi-electron delocalization. Hydroxyl vibrations with intramolecular H-bonding are analyzed, supported by the computed results. The natural bond orbitals (NBO) analysis confirms this strong hydrogen bond between the hydrogen of the hydroxyl group and nitrogen of the azo group of the molecule. Assignments of benzene and naphthalene ring vibrations are found to agree well with the theoretical wave numbers.     

13C NMR spectra and structure of hydroxy- and amino-substituted azo derivatives of benzene and naphthalene

Conclusions It was shown by the¹³C NMR method that the hydroxy- and amino-substituted azo derivatives of benzene and naphthalene have an azo structure under the studied conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1185–1188, May, 1984.The authors are grateful to N. V. Korsakov and L. N. Savos'kin for supplying some of the compounds.     

Polarized infrared spectroscopic study on changes in molecular orientation and interaction during phase transitions of a ferroelectric liquid crystal with a naphthalene ring

Temperature-dependent polarized infrared spectra were measured over the temperature range 105-30°C for a ferroelectric liquid crystal with a naphthalene ring (FLC-1) in the isotropic, smectic A (SmA), and chiral smectic C (SmC*) phases to investigate its molecular conformation, interactions, and alignment in each phase. It has been found, from the temperaturedependent spectral changes in the 1610-1600 cm^-1 region, that the degree of twist between the naphthalene and benzene rings of FLC-1 changes with temperature. The peak intensity of the band at 1606 cm^-1 containing contributions from both the benzene and naphthalene ring stretching modes begins to decrease, not suddenly but gradually, upon going from the SmA phase to the SmC* phase, suggesting that the molecular orientation of the two rings changes gradually between the two phases. The frequencies of two CH₂ stretching bands suggest that the disorder of the alkyl chain of FLC-1 is similar for the liquid crystal phase and the isotropic liquid phase. The splitting of the core C=O stretching band indicates that the resonance system consisting of the benzene ring and the C=O group in the core part of FLC-1 is involved in two kinds of intermolecular interaction between adjacent molecules in the liquid crystal phase.     

Thermodynamics of surfactant-dye complex formation in aqueous solutions II. Sodium dodecyl sulfate and some azo oil dye systems

Spectrophotometric and thermodynamic investigations are reported of the interactions between anionic surfactant (sodium dodecyl sulfate) and six azo oil dyes (benzene azo naphthalene type) which have an amino group at 4-position of naphthalene. A pronounced spectral change in the dye solution occurs on addition of surfactant. For increasingly surfactant concentrations (below the CMC), the interaction between dye and surfactant is so sharp that the systems may be said to exhibit an isosbestic point; then a new absorption band appears at longer wavelengths. The spectral data can be quantitatively interpreted in terms of a complex formation. The equilibrium coefficients of the complex formation are determined at different temperatures. The thermodynamic parameters of the complex formations (the free energy change (G), enthalpy change (H) and change in entropy (S) are also calculated. The reaction of complex formation is exothermic (H negative).G is dependent on the hydrophobic nature andpKa of the dye. These complexes will form due to hydrophilic-hydrophilic interaction and will become more stable due to hydrophobic-hydrophobic interaction.With increasing amounts of complex, the infinite adsorption, the exhaustion and the rate constant of dyeing for nylon decrease.     

Photoinduced intramolecular charge transfer (ICT) reaction in trans-methyl p-(dimethylamino) cinnamate: A combined fluorescence measurement and quantum chemical calculations

The photophysical behaviour of trans-methyl p-(dimethylamino) cinnamate (t-MDMAC) donor–acceptor system has been investigated by steady-state absorption and emission spectroscopy and quantum chemical calculations. The molecule t-MDMAC shows an emission from the locally excited state in non-polar solvents. In addition to weak local emission, a strong solvent dependent red shifted fluorescence in polar aprotic solvents is attributed to highly polar intramolecular charge transfer state. However, the formation of hydrogen-bonded clusters with polar protic solvents has been suggested from a linear correlation between the observed red shifted fluorescence band maxima with hydrogen bonding parameters (). Calculations by ab initio and density functional theory show that the lone pair electron at nitrogen center is out of plane of the benzene ring in the global minimum ground state structure. In the gas phase, a potential energy surface along the twist coordinate at the donor (–NMe₂) and acceptor (–CH = CHCOOMe) sites shows stabilization of S₁ state and destabilization S₂ and S₀ states. A similar potential energy calculation along the twist coordinate in acetonitrile solvent using non-equilibrium polarized continuum model also shows more stabilization of S₁ state relative to other states and supports solvent dependent red shifted emission properties. In all types of calculations it is found that the nitrogen lone pair is delocalized over the benzene ring in the global minimum ground state and is localized on the nitrogen centre at the 90° twisted configuration. The S₁ energy state stabilization along the twist coordinate at the donor site and localized nitrogen lone pair at the perpendicular configuration support well the observed dual fluorescence in terms of proposed twisted intramolecular charge transfer (TICT) model.     

Photo Catalytic Degradation of Azo Dyes over Mn2+ Doped TiO2 Catalyst under UV/Solar Light:An Insight to the Route of Electron Transfer in the Mixed Phase of Anatase and Rutile

Mn²⁺ ion was doped into the TiO₂ matrix and its photocatalytic activity was evaluated for the degradation of a mono azo dye methyl orange (MO) and a di‐azo dye brilliant yellow (BY) under UV/solar light. X‐ray diffraction results revealed the phase transformation from anatase to rutile due to the inclusion of Mn²⁺ ion into the TiO₂ matrix. All the doped catalysts showed a red shift in the band gap to the visible region. The degradation reaction of the dyes was found to be dependent on its structure. It was found that mono azo dye degrades faster than di azo dye under UV/solar light. The rate constant under identical conditions calculated for the degradation of MO is 2.4 times (under UV light) and 4.5 times (under solar light) higher compared to BY. Among the photocatalysts studied, Mn²⁺(0.06 at.%)‐TiO₂ showed higher activity under both UV and solar light illumination. The synergestic effect in the bicrystalline framework of anatase and rutile effectively suppresses the charge carrier recombination and enhances the photocatalytic activity. The degradation reaction was followed by UV‐visible spectroscopy and the photoproducts formed were analyzed by GC‐MS techniques.     

偶氮染料吸附和光催化氧化动力学

以甲基橙和酸性大红两种偶氮染料为模拟污染有机物,对它们的暗吸附和光催化氧化行为进行研究.实验结果表明,两种偶氮染料的吸附受溶液酸碱度影响很大,酸性（pH=3）条件下,两种染料吸附量都很大,酸性大红吸附量更大；近中性（pH≈6）时两种染料的吸附显著减少；碱性（pH=9）条件下两种染料不发生吸附.光催化反应结果显示,碱性条件或酸性条件下两种染料降解速度都很快.说明在不同酸碱度条件下,光催化反应按不同机理进行.酸性条件下,反应在催化剂表面进行,在碱性介质中,光催化氧化在溶液中进行.提出了一个碱性条件下的动力学方程,经过进一步简化,可以得到表观一级方程,形式上和准一级L-H方程十分相似,但其含义不同.     

Synthesis and study of azo dye compounds: variation of mesogenic behaviour with length of alkyl chains

The mesogenic behaviours of two azo dye liquid crystals, 1 and 4, differ because of the different length of terminal alkyl chains; azo dye 1 shows a SmB phase, azo dye 4 shows nematic and SmA phases during thermal processing. The molecular stackings of these two azo dye liquid crystals are compared on the basis of crystallographic studies to explain such unexpected mesogenic behaviour.     

十氢萘在分子筛催化剂上的开环反应研究

在小型固定流化床(FFB)装置中研究了Y分子筛与ZSM-5分子筛催化剂上的十氢萘裂化开环反应性能,考察了温度和剂油比对Y分子筛开环反应催化性能的影响。结果表明,十氢萘在分子筛催化剂上通过环烷环开环反应生成丙烷、丙烯、丁烷、丁烯、甲基戊烷和环戊烷、环己烷等非芳烃以及苯、C_1~4烷基取代苯等单环芳烃,并通过脱氢缩合反应生成四氢萘、萘、甲基萘和菲、芘等多环芳烃甚至焦炭等。由于扩散和吸附性能的影响,ZSM-5分子筛催化剂的裂化开环反应选择性比Y分子筛催化剂的高,因此,十氢萘环烷环开环与脱氢缩合反应的相对比例(NRO/DHC)在ZSM-5分子筛催化剂上较高。在Y分子筛催化剂上,温度为450~550 ℃、剂油比为3~9,反应温度升高或者剂油比增加,双分子氢转移以及脱氢缩合反应增强,从而导致环烷环开环产物选择性降低。     

Experimental and computational studies of structure and bonding in parent and reduced forms of the azo dye Orange II

The structure and bonding of the azo dye Orange II (Acid Orange 7) in parent and reduced forms have been studied using NMR, infrared, Raman, UV-visible, and electron paramagnetic resonance (EPR) spectroscopy, allied with density functional theory (DFT) calculations on three hydrazone models (no sulfonate, anionic sulfonate, and protonated sulfonate) and one azo model (protonated sulfonate). The calculated structures of the three hydrazone models are similar to each other and that of the model without a sulfonate group (Solvent Yellow 14) closely matches its reported crystal structure. The 1H and 13C NMR resonances of Orange II, assigned directly from 1D and 2D experimental data, indicate that it is present as > or = 95% hydrazone in aqueous solution, and as a ca. 70:30 hydrazone:azo mixture in dimethyl sulfoxide at 300 K. Overall, the experimental data from Orange II are matched well by calculations on the hydrazone model with a protonated sulfonate group; the IR, Raman, and UV-visible spectra of Orange II are assigned to specific vibrational modes and electronic transitions calculated for this model. The EPR spectrum obtained on one-electron reduction of Orange II by the 2-hydroxy-2-propyl radical (*CMe2OH) at pH 4 is attributed to the hydrazyl radical produced on protonation of the radical anion. Calculations on reduced forms of the model dyes support this assignment, with electron spin density on the two nitrogen atoms and the naphthyl ring; in addition, they provide estimates of the structures, vibrational spectra, and electronic transitions of the radicals.