Modulating the Photochemistry of Bipyridylic Compounds by Symmetric Substitutions

A quantum electronic study of the effect of substituents on (2,2′‐bipyridyl)‐3,3′‐diol and (2,2′‐bipyridyl)‐3,3′‐diamine is presented. A large difference in the photochemical behavior between the original and the substituted selected systems is expected. For the sake of simplicity, the study is restricted to the symmetrically bi‐substituted compounds: fluorine, the more electronegative atom and thus a strong σ‐acceptor but also a weak π‐donor group, and NO₂, a strong π‐acceptor substituent. Among the large set of compounds studied, two receive special attention: 5,5′‐dinitro‐(2,2′‐bipyridyl)‐3,3′‐diamine and 6,6′‐difluoro‐(2,2′‐bipyridyl)‐3,3′‐diol. While in the former case the nitro substitution transforms (2,2′‐bipyridyl)‐3,3′‐diamine, previously suggested to behave as a photomemory material, into a simple fluorescent species, the latter substitution turns (2,2′‐bipyridyl)‐3,3′‐diol into a fresh new candidate for a photomemory device.     

低温相GeO2晶体的合成及其电子结构与光学性质第一性原理计算

通过低温水热的合成方法合成了一例新的低温相GeO₂晶体(l-GeO₂), 并对其进行了红外光谱、热重以及X射线衍射的分析表征. 晶体学测试结果表明, l-GeO₂属于四方晶系, P4/mcc空间群, 晶胞参数a＝b＝8.832(4) Å, c＝14.479(7) Å, V＝1129.4(9) ų, Z＝4, R₁＝0.0629, wR₂＝0.1540. 晶体结构中包含一个由4个双四元环单元(D4R)和4个GeO₄四面体交替相连而形成的沿[001]方向的一维(1D) 12-元环孔道. 采用密度泛函理论下的第一性原理平面波超软赝势方法, 对l-GeO₂的电子结构和光学性质进行了理论计算. 计算结果表明l-GeO₂为直接带隙半导体, 带宽为3.31 eV|其价带主要由O的2p电子构成, 导带主要由Ge的4s和4p态电子构成|静态介电常数ε₁(0)＝1.92, 折射率n(0)＝1.24, 吸收系数最大峰值为8.9×10⁴ cm^－1, 最大反射率为12%. 比较分析了l-GeO₂与石英相GeO₂ (q-GeO₂)和金红石相GeO₂ (r-GeO₂)的复介电函数、复折射率、吸收谱以及反射谱等光学性质的异同点. 结果显示l-GeO₂的能带结构和光学性质与q-GeO₂较接近, 与r-GeO₂的相差较大.     

Synthesis and Structure of an Enantiomerically Pure C2 Symmetric Ferrocenyl Carbene

The straightforward, high‐yield synthesis and X‐ray structural analysis of the air‐stable planar‐chiral bis(ferrocenyl)carbene 1,3‐bis‐{(1R)‐1‐[(1R)‐1‐(trimethylsilyl)ferrocen‐2‐yl]ethyl}imidazol‐2‐ylidene ( 5 ) is reported. Compound 5 is obtained in four steps from the amine [(1R)‐1‐(dimethylamino)ethyl]ferrocene ( 1 ) upon diastereoselective silylation, methylation, nucleophilic substitution by imidazole, and deprotonation. The X‐ray crystal structure of the free carbene shows the typical conformational features of the 1,2‐disubstituted ferrocenyl units, as found in other ferrocenyl ligands derived from 1 .     

Synthesis,Crystal Structure and Electronic Structure of Novel Semiconducting KCdAsS_3

A new compound of KCdAsS_3(Mr = 322.60) was successfully synthesized using thiourea reactive flux method. The crystal structure was determined by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of space group P21/n with a = 5.9537(7), b = 16.633(3), c = 6.093(1) ?, b = 90.781(3)°, V = 610.0(1) ?3, Z = 4, Dc = 3.513 g/cm3, m(Mo Kα) = 10.52 mm-1, F(000) = 592, R = 0.057 and w R = 0.136 for 899 observed reflections with I 2σ(I). The crystal structure of KCdAsS_3 features [Cd As S3]-layers, which are separated by K+ ions. First-principles calculations show that KCdAsS_3 is an indirect band gap semiconductor with a band gap of 2.3 e V. The novel layered compound of tetrahedra CdS_4 and pyramids AsS_3 is potentially useful for photoluminescent, photocatalytic and photoelectric applications.     

Synthesis,Characterization and Electronic Properties of a Symmetric Bidentate Schiff-Base Ligand and Its Complex with CadmIum(II)

A symmetric bidentate Schiff-base ligand and its complex with Cd(II) is described. The ligand and its complex were characterized by microanalysis, UV-Vis, GC-Mass and FT-IR spectroscopic methods. The present work also studied the structures and electronic properties of the bidentate Schiff-base ligand by using ab initio and AM1 molecular orbital methods. Ab initio and AM1 geometrical predictions have been compared. The analysis of molecular orbitals (MOs) indicates that the N(3) and N(6) atoms could be the coordination sites in this ligand.     

Synthesis of Peripherally Nitrated,Aminated, and Arylaminated Subporphyrins

2‐Nitro‐5,10,15‐tri(4‐tert‐butylphenyl)subporphyrin 2 was prepared by the nitration of 5,10,15‐tri(4‐tert‐ butylphenyl)subporphyrin 1a with five equivalents of Cu(NO₃)₂ ? 5 H₂O in a mixed EtOAc/Ac₂O solution and was reduced into 2‐amino‐5,10,15‐tri(4‐tert‐butylphenyl)subporphyrin 3 . Bromination of 5,10,15‐triphenylsubporphyrin 1b with 1.5 equivalents of N‐bromosuccinimide (NBS) gave 2‐bromo‐5,10,15‐triphenylsubporphyrin, which was converted into various 2‐arylamino‐5,10,15‐triphenylsubporphyrins ( 4a , 4b , 4c , 4d ) and 2‐benzamido‐5,10,15‐triphenylsubporphyrin 5 through Pd‐catalyzed cross‐coupling reactions. These molecules constitute the first examples of mono‐β‐substituted subporphyrins. These subporphyrins exhibit significantly perturbed optical and electrochemical properties, which reflect a large influence of the peripherally attached substituents on the electronic networks of subporphyrins.     

Synthesis,Crystal and Electronic Structure of Ba_3ZnSb_2O_9 with the 6H-perovskite-type Structure

Crystals of Ba3ZnSb2O9 have been grown by a high-temperature solid-state reaction and characterized by single-crystal X-ray diffraction.Ba3ZnSb2O9 crystallizes in the hexagonal P63/mmc space group with a = 5.8663(4),c = 14.478(2) ,V = 431.49(8) 3,Z = 2 and R(all data) = 0.0167.The structure of Ba3ZnSb2O9 consists of pairs of face-sharing Sb2O9 bi-octahedra connected via corners with two single layers of mutually isolated ZnO6 octahedra.Each Ba2+ ion is bonded to 12 oxygen atoms.The UV-vis absorption spectrum of the compound has been investigated.Additionally,the calculations of band structure and density of states have also been performed with density functional theory method.The obtained results tend to support the experimental data of the absorption spectrum.     

莫来石的低温合成与结构研究

通过在高岭土中引入质量分数为1%～5%的钒以后,在700℃左右的较低温度下观察到莫来石相的生成,并结合酸、碱抽提反应过程制得较纯的莫来石.进一步研究了低温莫来石点阵参数的测定方法,发现低温钒-莫来石的晶胞体积比常规的高温莫来石大,表明钒进入了莫来石的骨架结构.另外,低温莫来石的形成动力学可表述为钒-高岭石低温共熔体迁移过程.     

A Monomeric Stannabenzene: Synthesis,Structure, and Electronic Properties

A tin‐containing benzene, stannabenzene, was synthesized and isolated as a monomeric form. The X‐ray crystallographic analysis revealed the planar structure of the stannabenzene ring and unsaturated Sn?C and C?C bonds without bond alternation. Low‐field shifted NMR signals and negative nuclear‐independent chemical shifts (NICS) values are in agreement with the features of aromatic compounds. The narrow HOMO–LUMO gap of stannabenzene has been revealed by UV/Vis spectroscopy and electrochemistry.     

A Monomeric Stannabenzene: Synthesis,Structure, and Electronic Properties

A tin‐containing benzene, stannabenzene, was synthesized and isolated as a monomeric form. The X‐ray crystallographic analysis revealed the planar structure of the stannabenzene ring and unsaturated Sn?C and C?C bonds without bond alternation. Low‐field shifted NMR signals and negative nuclear‐independent chemical shifts (NICS) values are in agreement with the features of aromatic compounds. The narrow HOMO–LUMO gap of stannabenzene has been revealed by UV/Vis spectroscopy and electrochemistry.     

对称偶氮苯的合成及性质

以Cu(Ⅰ)催化的氨基偶联反应为关键步骤,合成了末端各带3条柔性烷基链的最简单小分子偶氮凝胶剂——对称偶氮苯化合物A;通过~1H NMR,~(13)C NMR和元素分析鉴定了其结构;采用紫外光谱和SEM等手段对其性质进行了表征.凝胶实验结果表明,该化合物能在极性、非极性有机溶剂中形成凝胶,且该凝胶在紫外光和可见光照射下能够发生凝胶-溶液的可逆转化.SEM表征结果表明,该凝胶具有由纤维束聚集成的三维网状结构,此外还具有热响应性和机械响应性.紫外光谱测试结果表明,该化合物具有光响应性.     

邻羧基苯甲酰二茂铁钠的合成、晶体结构及电化学性质

参照文献方法合成了邻羧基苯甲酰二茂铁钠,首次培养得到了它的单晶．发现在其固态结构中,邻羧基苯甲酰二茂铁阴离子与四水合钠阳离子通过分子内氢键相互作用;分子间的氢键又把多个二茂铁衍生物分子连接成二维的网状结构．研究了标题化合物在甲醇溶液中的电化学性质．     

不同桥联二噻吩低带隙给受体共聚物的电子结构和光物理性质的理论研究

本文主要是通过分析吸收光谱性质来区分用于体异质结聚合物太阳能电池的两种不同桥联低带隙给受体共聚物PCPDTBT和PSBTBTS的激发态特征,进而通过分析电荷转移态（CT）特征来区分二者实现电荷分离的难易程度. 利用密度泛函理论(DFT/TD-DFT)B3LYP和CAM-B3LYP方法计算PSBTBT和PCPDTBT(n=1~4)的电子结构和光谱性质. 结果表明,从吸收光谱来看,PSBTBT与PCPDTBT的光谱相似,与太阳光谱的匹配能力相当. 而激子解离能表明二者的电荷转移态（CT）电荷分离的难易程度也相当. 然而用Si原子取代C原子后,C-Si键长明显长于C-C键长,降低了噻吩环和烷基链间的空间位阻,从而可能有利于其结晶度的提高,更加有利于载流子的传输,因此从理论上说明PSBTBT也可能具备高效太阳能电池给体材料的潜质.     

Structure and conformation of heterocycles—VIII : Peripherally substituted 1,4,5,8-tetraoxadecalins

The synthesis of the title compounds was examined and a mechanistic scheme was put forward, which accounts for their formation along with higher substituted by-products and with the corresponding bidioxolan-2-yl isomers.Chemical correlation between two members of the series, trans -2,3-dicarbomethoxy- and trans-2, 3 - dimethyl - tetraoxadecalin, was performed.All stereoisomeric 2,3 - dicarbomethoxy -1,4,5,8- tetraoxadecalins were prepared and chemically equilibrated. The free energy differences at 65° between them were thus obtained. This led to an evaluation of the conformational free energy of the carbomethoxy group in dioxanes, ΔG_CO2Me^o. = 0.38 kcal/mole.Dynamic conformational analysis by variable temperature NMR measurements on cis - 2, 3 -dicarbomethoxy - anti -cis - 1, 4, 5, 8- tetraoxadecalin led to a ring inversion barrier of AG₁₉₃^≠ = 10.0 kcal/mole.     

ChemInform Abstract: Synthesis,Structure, and Electronic Structure of CsAgGa2Se4.

The new title compound is prepared from a mixture of AgGaSe₂ (obtained from the elements at 900 °C, 2 d) and CsI in the molar ratio 1:2 (silica tube, Ar, 800 °C, 48 h).     

Synthesis,Crystal Structure,Magnetic Property,and Electronic Structure of Ba2YbInSe5

A new barium ytterbium indium selenide, Ba₂YbInSe₅, was obtained by conventional high temperature solid state reaction. The compound crystallizes in the noncentrosymmetric space group Cmc2₁ of the orthorhombic system. The structure contains infinite one‐dimensional anionic chains ¹_∞[YbInSe₅]^4–, which are built from YbSe₆ octahedra and InSe₄ tetrahedra and separated by Ba²⁺ cation. The magnetic measurement indicates that the compound is paramagnetic. In addition, the calculated bandgap is 0.29 eV.     

折叠型双银配合物电子结构与相关性质

在密度泛函B3LYP/LanL2DZ的水平上,对具有π-π弱相互作用调控的折叠型银配合物Ag₂(MPTQ)₂²⁺进行计算研究。探讨该配合物的电子结构、成键特征、π-π弱相互作用机理、电荷布居及其相关性质。计算结果表明,Ag…Ag之间存在弱的直接相互作用,HOMO主要布居在配体中芳香环的σ-p轨道、S的σ-p轨道及与S相连的C12的S轨道上,LUMO主要布居在配体中芳香环的π^*-p轨道上,基态电子光谱主要是配体中的n→π^*跃迁产生的电荷转移光谱。论文还讨论了分子间π-π弱相互作用的本质及活性部位等。计算结果能较好地解释实验现象与规律。     

Synthesis and Characterization of New Phthalocyanines Peripherally Fused to Four 13-Membered Tetrathiamacrocycles

The new metal-free phthalocyanine 5 and phthalocyaninatometals 6–8 (M=Co, Ni, or Zn) fused in peripheral positions with four 13-membered tetrathiamacrocycles were prepared by cyclotetramerization of 2, 3, 6, 7, 9, 10-hexahydro-5H-[1, 4, 8, 11]benzotetrathiacyclotridecine-13, 14–dicarbonitrile in the presence of a suitable metal salt or a strong organic base. In contrast to the aza- or oxamacrocycle-fused analogs, the solubility of these phthalocyanines is very low. Complexation of the tetrathiamacrocycles of 7 and 8 with Pd^II or Ag^I to form pentanuclear products was accomplished from their suspensions.