Synthesis and X-ray Crystal Structures of Two Luminescent Imidazopyridinium Derivatives from the Corresponding N-(aryl)-Pyridine-2-aldimines

Syntheses and X-ray structural characterizations of two new luminescent imidazopyridinium derivatives, 2-(phenyl)-N(3)-(4(methyl)phenyl)-imidazo[1,5a] pyridinium perchlorate (1) and 2-(pyridyl)-N(3)-(4-(chloro)phenyl)-imidazo[1,5a] pyridinium perchlorate (2) are reported. The compounds are prepared in one step from N-(4-(methyl)phenyl) pyridine-2-aldimine and N-(4-(chloro)phenyl) pyridine-2-aldimine respectively in a transformation mediated by Mn(OAc)₂-KMnO₄ mixture. It is found that the molecular structures of the two compounds are similar. In the solid state, 1 forms a three-dimensional network through a series of hydrogen bonds between the cations and anions in the lattice while 2 forms a similar but less extensively linked network. The substitution of hydrogen at the 2-position of the imidazopyridinium ring by phenyl or 2-(pyridyl) affects the nature of their first excited states as detected by changes in their emission and absorption spectra.     

Molecular Self Assembly: Solvent Guests Tune the Conformation of a Series of 2,6-Bis(2-anilinoethynyl)pyridine-Based Ureas

The conformations of 2,6-bis(2-anilinoethynyl)pyridine-based urea receptors were studied by single crystal X-ray diffraction methods and revealed a rich conformational flexibility influenced by solvents. Whereas receptor L(1) in DMSO prefers an "S" conformation, receptor L(1) crystallizes in an "O" conformation from DMSO/CH(3)OH binary solvent system, and a "W" conformation in the ternary solvent mixture DMSO/toluene/1,4-dioxane. In the case of L(2), the molecule adopts an "S" conformation where water molecules are sandwiched between two molecules of L(2) to form a dimer. Similar to L(2), L(3) also forms a dimer where water molecules are sandwiched between L(3) molecules, which are capped with two molecules of DMSO. Such a capping DMSO solvate is lacking in the case of L(2). Taken together, these results demonstrate that the conformation of 2,6-bis(2-anilinoethynyl) pyridine-based urea receptors can be dramatically manipulated and tuned by the choice of crystallization solvents.     

共生晶体Mn2Hg4(SCN)12和MnHg(SCN)4的形成

采用恒温蒸发法从水溶液中生长Hg2+、Mn2+为双配位中心的SCN- 的配合物晶体.生长液中Hg2+含量较SCN-适当过量的条件下,出现Mn2Hg4(SCN)12晶体和MnHg(SCN)4晶体共生现象.MnHg (SCN)4晶体中Hg2+只与SCN-配位,Mn2+只与NCS-配位,而Mn2Hg4(SCN)12晶体中部分Hg2+可以同时与SCN-和NCS-配位体结合,并且部分SCN-同时和2个Hg2+结合成桥式结构.Mn2Hg4(SCN)12晶体中Mn2+的配位数由MnHg(SCN)4晶体中的4配位增大为5配位和6配位.Mn(NCS)4-6 和Mn(NCS)3-5 配位多面体的存在使Mn2Hg4(SCN)12晶体的颜色比MnHg(SCN)4晶体的颜色浅.     

Optical and magnetic properties of (Zn,Mn)O nanostructures synthesized by CVD method

We report on microstructural, optical and magnetic properties of (Zn,Mn)O nanostructures synthesized by a chemical vapor deposition (CVD) technique. Average diameters of the as grown (Zn,Mn)O nanorods and nanowires were ∼400 nm and ∼50 nm, respectively. X‐ray diffraction (XRD) and photoluminescence (PL) spectra provided the evidence that Mn was incorporated into ZnO lattice. PL spectra of the (Zn,Mn)O nanostructures showed shift in near band edge (NBE) emission at 396 nm together with a green band (GB) emission at 510 nm and a blue band (BB) emission at 460 nm. Magnetic measurements revealed mixed magnetic phases (ferromagnetic and antiferromagnetic) in the (Zn,Mn)O nanostructures. Vapor‐solid‐solid (VSS) mechanism was thought to be responsible for the growth of the nanostructures at low temperatures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal and molecular structure of nitrato-1,4,10-trioxa-7,13-diazacyclopentadecanecopper(II) nitrate,C10H22N2O3·Cu(NO3)2

The copper(II) dinitrate complex of the title heteromacrocycle has been investigated by X-ray diffraction. The structure was solved by direct methods and refined by a full-matrix least-squares, givingR=0.0318 with 1778 unique reflections. The Cu(II) cation is coordinated inside the N(7), N(13)-folded macrocycle. The coordination sphere of Cu(II) is a distorted square pyramid with N(7), O(10), N(13) of the macrocycle and O(1a) of the nitrate anion atoms occupying the corners of the base of the pyramid and the O(1) macrocycle atom in the apical position. The other nitrate group was found in a remote position with respect to the Cu(II) cation.     

Crystal Structure of a Metallohybrid Acid of 1,3,5-Benzenetricarboxylic Acid of Copper(II)

Abstract The crystal structure of a metallohybrid carboxylic acid obtained from the reaction of 1,3,5-benzenetricarboxylic acid (TCAH3) with copper(II)acetate monohydrate in the presence of pyridine (py) having composition Cu(py)₂(TCAH2)₂(H₂O)₂ [1] is reported. It crystallizes in triclinic space group P-1 and with a = 7.0110(3)?, b = 8.9523(5)?, c = 11.5370(5) ?, α = 79.776(3) °, β = 82.881(3)°, γ = 83.628(3)°, and V = 704.18(6)?³. The hydrogen bond in 1 is compared with the hydrogen bond pattern in the structure of 1,3-dicarbomethoxy 4,6-benzenedicarboxylic acid, which crystallizes in mononclinic space group P21/c and has unit cell parameters of a = 6.9549(16)?, b = 8.7676(15)?, c = 20.111(4)?; β = 92.585(17) ° and V = 1225.1(4) ?³. Index Abstract Crystal structure of a metallohybrid carboxylic acid obtained from the reaction of 1,3,5-benzenetricarboxylic acid with copper(II)acetate monohydrate in the presence of pyridine is determined and compared with hydrogen bond pattern present in the structure of 1,3-dicarbomethoxy 4,6-benzenedicarboxylic acid. Crystal structure of a metallohybrid acid of 1,3,5-benzenetricarboxylic acid of copper(II). Kusum Bania, Nilotpal Barooah, Rupam Sarma, Jubaraj B. Baruah     

Synthesis and Characterization of Novel Liquid Crystalline Epoxy Resin with Low Melting Point

A liquid crystalline epoxy resin (LCE) having α-methylstilbene as a mesogenic unit and an ethylene-oxy unit as a spacer (DGE(C2-MS-C2)) was synthesized and characterized. DGE (C2-MS-C2) has a lower melting point (MP) compared to the diglycidylether of 4,4′-dihydroxy-α-methylstilbene (DGEDHMS). The curing of DGE (C2-MS-C2) with diaminodiphenylethane (DDEt) in a mesophase generated a liquid crystalline (LC) network, which have a more highly layered structure than DGEDHMS. The LC network showed extensively large fracture energy on a tensile test. Introducing spacers outside the mesogen unit promotes the mesogen unit to form a highly ordered structure, which enhances the versatility of LC epoxy resins.     

Nanocomposite SiO2(Si) films as a medium for non-volatile memory

Nanocomposite SiO₂(Si) films containing Si nanocrystals (NCs) in a SiO₂ dielectric matrix obtained through (i) plasma enhanced chemical vapor deposition (PE CVD) or (ii) pulse laser deposition (PLD) have been investigated as a medium for charge storage. The C–V method was used to characterize charging effects in the MIS structure (capacitor) with a nanocomposite SiO₂(Si) film as an insulator. The obtained results indicate (i) the capture of small negative charge at the positive gate voltage in the nanocomposite SiO₂(Si) film, (ii) significant capture of positive charge at the negative gate voltage, and that (iii) the difference between the positive and negative charge captured in both cases cannot be explained by dropping a part of the positive gate voltage in the semiconductor’s depletion region. A model of charge transport and capture in nanocrystals of nanocomposite SiO₂(Si) film is proposed to explain the experimental results.     

一个新的铜(Ⅱ)配合物的合成、结构与抗微生物活性研究

利用苯妥英,二(3-氨基丙基)胺与醋酸铜反应合成了一种新的铜三元配合物[Cu(pht)2(bapa)](CH3OH)[Hpht:苯妥英(5,5-Diphenylhydantion);bapa:二(3-氨基丙基)胺(bis(3-aminopropyl)amine)].通过元素分析、红外光谱和X射线单晶衍射确定了其组成和结构.配合物属于三斜晶系,空间群为Pī.晶胞参数:a=0.84190(10)nm,b=1.37540(15)nm,c=1.5622(2)nm,α=86.038(3)°,β=82.542(2)°,γ=83.904(2)°;V=1.7807(4)nm3,Mr=729.32,Z=2,F(000)=766,Dc=1.360 g/cm3,μ=0.666 mm-1,R1=0.0692,wR2=0.1430.配合物中铜离子配位数为5,处于变形三角双锥配位环境中.测试了配合物、配体和铜盐的抑菌活性,结果表明,它们对4种细菌均有一定的活性.     

Paracrystalline Nature of Poly (p-Phenylene)

The electron diffraction pattern of oriented, annealed poly (p-phenylene) is explained on the basis of an orthorhombic unit cell: a = 0.7781, b = 0.5520 and c(fiber axis) = 0.4300 nm. and exhibits the following features:

(1)The reflections on the equator and meridian are sharp. Only a few weak diagonal reflections can be observed.

(2) Strong diffuse scattering is seen on the third layer line.

(3)The reflections on the meridian (00l-reflections) have a characteristic line profile. in which the intensity increases suddenly at the Bragg angle and decreases gradually.

From (1) to (3), it can be concluded that the material is paracrystalline like a nematic structure in liquid crystals. Molecular chains are laterally packed in a rather regular way. However, the disorder by the shift of chains in the direction parallel to their axes is remarkable.     

Synthesis and single crystal structure of a new polymorph of 5, 10, 15, 20-tetrakis-(4-chlorophenyl) porphyrin,H2TTPCl4: Spectroscopic investigation of aggregation of H2TTPCl4

5, 10, 15, 20-tetrakis-(4-chlorophenyl) porphyrin, H₂TTPCl₄, has been isolated as a new polymorph following the modified Adler’s method and its X-ray crystal structure solved. The new polymorph (I) crystallises in the monoclinic space group, P2₁/n with a?=?10.1574(5) Å, b?=?8.9827(4) Å, c?=?20.9350(8) Å, β?=?102.532(4)°, V?=?1864.62(15) ų, Z?=?2. The previously found polymorph, prepared using Lindsay method was crystallised in monoclinic space group, P2₁/a with a?=?15.776 (13) Å, b?=?8.646 (3) Å, c?=?14.087 (5) Å, β?=?96.05 (5)°, V?=?1910.7 (3) ų, Z?=?2. The main difference between the two polymorphs seems to be the different packing arrangement of molecules in their crystal lattices. The dramatic self aggregation property of new polymorph (I) has also been investigated. The investigation reveals that under certain conditions of solute concentration and pH of the media, the compound exhibits a strong tendency to exist in a prominent self aggregated state in head-to-tail type (j-aggregation) molecular alignment. The self association behaviour of (I) was confirmed by UV-Vis absorption spectra, performed in chloroform by varying concentrations and pH changes and ¹H NMR spectra, performed in deuterated chloroform at varying concentrations and their results have been discussed in detail.     

Precise electrical evaluation of active oxides thickness and comparison with TEM measurements

In this paper we propose a new model to describe the quantum effects at the SiO₂/Si interface of metal-oxide–semiconductor (MOS) devices. Using this model we developed a method to extract the thickness of thin oxides (in the range of 3–20 nm) from capacitance (C) as a function of voltage (V) measurements, C(V). The results of our extraction are in good agreement with transmission electron microscopy (TEM) measurements, within the accuracy of both techniques, while classical electrical methods are inadequate for a precise evaluation of the oxide thickness. Moreover this new method is suitable for in-line monitoring of oxide thickness in advanced MOS processes.     

The effect of redox state on the local structural environment of iron in silicate glasses: a combined XAFS spectroscopy, molecular dynamics, and bond valence study

A series of 27 silicate glasses of various compositions containing 0.2-2 at.% iron were synthesized at various oxygen fugacity values. The glasses were examined using X-ray absorption fine structure (XANES) spectroscopy at the Fe K-edge in order to determine iron oxidation state and first-neighbor coordination number. Spectral information extracted from the pre-edge region and principal component analysis (PCA) of the XANES region, together with a spectral inversion, were used to derive the end-member spectral components for Fe(II) and Fe(III). Linear trends in the pre-edge features were observed for most compositional series of the glasses examined as a function of Fe(II)/Fe(III) content. These linear trends are believed to be due to the similarity of average coordination numbers for both Fe(II) and Fe(III) end-members in each series. This result is consistent with model simulations of the XANES region and molecular dynamics (MD) simulations for the two end-member compositions which also show that Fe(II) and Fe(III) have similar average coordination numbers. These simulations also suggest the presence of five-coordinated Fe(III) in the melt phase. Based on a bond valence analysis of these MD simulations, a simple model is proposed to help predict the speciation of iron in oxide and silicate glasses and melts.     

Transmission electron microscopy observation of GaAs/Al0.3Ga0.7As T-shaped quantum well structure fabricated by glancing angle molecular beam epitaxy on GaAs(100) reverse-mesa etched substrates

GaAs/Al_0.3Ga_0.7As multi-layer structures were grown on GaAs (100) reverse-mesa etched substrates by glancing angle molecular beam epitaxy (GA-MBE). A(111)B facet was formed as a side-facet. Surface migration of Ga and Al atoms from the (100) flat region to the (111)B side-facet region has been investigated to fabricate T-shaped GaAs/AlGaAs quantum wells (QWs) under the condition that Ga and Al atoms impinge only an the (100) flat region and do not impinge on the (111)B side-facet. Observation of T-shaped GaAs/AlGaAs quantum wires (QWRs) by cross-sectional transmission electron microscopy (TEM) revealed that there is no migration of Al atoms from the (100) to the (111)B facet region at a substrate temperature (T_s) as high as 630°C, under a V/III ratio of 28 (in pressure ratio). On the other hand, very thin GaAs epitaxial layers grown on the (111)B side-facet region owing to the Ga migration were observed for substrate temperatures of 600 and 630°C. It was found that the mass flow of Ga atoms from the (100) region to the (111)B side-facet region increases, with the thermal activation energy of 2.0 eV, as the substrate temperature increases from 570 to 630°C. The GA-MBE growth on a reverse-mesa etched GaAs substrate at a low temperature 570°C or lower is desirable to fabricate a nm-scale GaAs/AlGaAs QWR structure with nm-scale precision.     

Luminescence of GaN single crystals prepared by heating a Ga melt in Na–N2 atmosphere

Colorless transparent prismatic crystals (0.5‐2.0 mm long) and hopper crystals (1.0‐2.5 mm long) of GaN were prepared by heating a Ga melt at 800°C in Na vapor under N₂ pressures of 7.0 MPa for 300 h. The photoluminescence (PL) spectrum of a prismatic crystal at 4 K showed the emission peaks of neutral donor‐bound exciton (D⁰‐X) and free exciton (X_A) at 3.472 eV and 3.478 eV, respectively, in the near band edge region. The full‐width at half‐maximum (FWHM) of (D⁰‐X) peak was 1.9 meV. The emission peaks of a donor–acceptor pair transition (D⁰‐A⁰) and its phonon replicas were observed in a lower energy range (2.9‐3.3 eV). The emission peaks of the D⁰‐A⁰ and phonon replicas were also observed in the cathodoluminescence (CL) spectrum at 20 K. The (D⁰‐X) PL peak of a hopper crystal at 4 K was at 3.474 eV (2.1 meV higher), having a FWHM of 6.1 meV which was over 3 times larger than that of the prismatic crystal. A strong broad band with a maximum intensity around 1.96 eV was observed for the hopper crystals in the CL spectrum at room temperature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

PbWO4晶体中铅氧空位对对晶体光学性质的影响

本文利用完全势缀加平面波局域密度泛函近似,按照能量最低原理采用共轭梯度方法,对含铅氧空位对的PbWO4晶体进行结构优化处理.在此基础上,计算了含铅氧空位对的PbWO4晶体的电子结构、复数折射率、介电函数及吸收光谱,并与完整的PbWO4晶体进行了比较.结果表明:PWO晶体中铅氧空位对的存在对PbWO4晶体的光学性质没有显著的影响.     

In situ immobilization on the silica gel surface and adsorption capacity of poly[4-methacroyloxy-(4′-carboxy-2′-nitro)-azobenzene] on toxic metals ions

Abstract

A new organo-mineral composite material has been synthesized by in situ immobilization of poly[(4-methacroyloxy-(4′-carboxy-2′-nitro)azobenzene on the silicagel surface. As a result of thermogravimetric analysis and DSC-MS analysis it has been found that the composition of synthesized composite includes 10,1?wt. % of polymer. It has been found that the synthesized composite exhibits the sorption ability in terms of microquantities of Cu (II), Cd (II), Pb (II) and Fe (III) ions in a neutral aqueous medium. The maximum degree of sorption of ions Cu (II), Pb (II) and Fe (III) is achieved during the first minutes of contact, and for Cd (II) ions the equilibrium is established within a day. The sorption capacity of silica gel as a result of modification by this polymer increases with respect to Cu (II) ions more than 14 times, with respect to Pb (II) ions - 5 times.     

The role of two coordination compounds as novel transparent nonlinear optical crystals

This paper reports the synthesis, structure and properties of two coordination compounds which are transparent in the visible region and show a relatively strong nonlinear optical (NLO) effect. The first crystal, Zn(2-NH₂py)₂CI₂ (2-aminopyridine zinc dichloride, DAZC), shows a SHG (second harmonic generation) effect 8 times as strong as that of KDP. X-ray single crystal structure analysis reveals that the molecule possesses a tetrahedron configuration around the zinc atom, and all the molecules are aligned in an almost fully parallel direction.The second compound, Zn(acac)₂(PhTU) (phenylthiourea zinc diacetylacetate, PZDA), shows a powder SHG effect as strong as 10 times that of KDP. X-ray single crystal structure analysis shows that the molecule possesses a square pyramidal configuration around the zinc ion, and the molecules are aligned almost in a parallel arrangement in the lattice. These two crystals may represent a novel strategy for designing new transparent NLO materials.     

新型复合功能晶体Cd4TbO(BO3)3结构与性能研究

为探索新型复合功能晶体材料,采用高温固相反应法合成了Cd4TbO(BO3)3多晶粉末,并以NaF-B2O3为助熔剂生长出了小晶体.结构分析表明,Cd4TbO(BO3)3晶体属于单斜晶系,Cm空间群,晶胞常数为a=7.982(1) (A)、b=15.806(3) (A)、c=3.487(7) (A)、α=90°、β=100.57°、γ=90°,晶体中的阴离子基团为[BO3].测量了TG-DSC曲线、紫外可见透过光谱、红外光谱、拉曼光谱,并计算了晶体单位体积Tb的含量.结果表明, Cd4TbO(BO3)3晶体在500~1500 nm范围内透过率大于70;.Cd4TbO(BO3)3晶体单位体积含Tb量为4.624×1021/cm3,是磁光晶体TGG单位体积含Tb量的0.3倍.综上表明Cd4TbO(BO3)3是一种有前途的复合功能晶体材料.     

Mesomorphic Properties of Di- (4 - Alkoxyphenyl) and Di- (4 - Alkanoyloxyphenyl) Tetrathiafulvalenes

The polymorphism of the di- (4 - alkoxyphenyl) and di- (4 - alkanoyloxyphenyl) tetrathiafulvalenes (TTF) is investigated. In the dialkoxy series, the short chain derivative exhibits a smectic G phase and a nematic phase. The latter phase disappears in the long chain derivative. The dialkanoyloxy derivatives exhibit a smectic G phase (for short chains) and a smectic C phase (for long chains). A plot of the mesormorphic-isotropic transition temperatures against the number of carbon atoms of the substituent shows the usual odd-even effect. Some tetra (alkoxyphenyl) tetrathiafulvalenes are described, unfortunately they have no mesomorphic properties.