Structures and nonlinear optical properties of polar 2-amino-1,2,3-triazolequinone derivatives

A series of phenyldialkylamine, dimethoxyphenyl, and nitrothiophene derivatives of 2-amino-1,2,3-triazolequinones was characterized by NMR, IR, mass spectroscopy, cyclic voltammetry, and chemical analyses. The solvatochromic procedure was used to evaluate the potential of nine compounds for nonlinear optical applications, and the possible failure of this model is discussed. The crystal structures of seven compounds were determined: (4) P2₁/c, a = 15.430(3) Å, b = 7.633(2) Å, c = 15.940(3) Å, = 105.19(3)° (5) P2₁/c, a = 20.201(2) Å, b = 9.6579(9) Å , c = 18.517(2) Å, = 95.907(2)° (6) P-1, a = 7.769(2) Å, b = 8.515(3) Å, c = 17.312(5) Å, = 89.347(7)°, = 83.219(6)°, = 86.001(7)° (7) P-1, a = 8.1365(7) Å, b = 8.9605(8) Å, c = 11.630(1) Å, = 79.553(2)°, = 75.048(2)°, = 82.080(2)° (8) P-1, a = 8.298(3) Å, b = 9.720(3) Å, c = 10.033(3) Å, = 84.803(6)°, = 83.735(6)°, = 77.659(5)° (10) P2₁/n, a = 8.4300(7) Å, b = 13.980(1) Å, c = 13.975(1) Å, = 106.590(2)° (12) P2₁/n, a = 7.715(2) Å, b = 14.206(3) Å, c = 12.758(3) Å, = 91.016(5)°.     

The crystal structure of 4-iodoacetophenone azine

4-Iodoacetophenone azine crystallizes in the space group Pbcn with cell parametersa = 34.5187(19), b = 7.2638(4), and c = 6.3736(3) Å. The azine shows a gauche conformation with regard to the N—N bond and the phenyl rings are twisted in a way that leads to the largest possible twist between the benzene rings of each azine. This azine conformation allows for intermolecular arene–arene T-contacts between pairs of benzene rings and these double-T contacts involve only molecules within the same layer. All azines are perfectly colinear within each layer and this results in a quadrilateral kite-shaped arrangement of iodine atoms at the interface of each layer. The iodine-iodine distances within each layer are 4.5 and 5.1 Å, and the three unique angles of the kite-shaped quadrilaterals are 97.1, 76.9, and 88.8°. The iodine atoms in adjacent layers pack such that atoms of one layer fill the square interstices of the next layer. The distances between iodine atoms in adjacent layers are 4.5 and 4.1 Å. The C—I bonds are not orthogonal to the I-planes and the direction of the molecules in adjacent layers causes a deviation of about 40° from colinearity     

Crystal structures of complexes of tri-, tetra-, or nonaethyleneglycol dimethyl ether with dichloropicric acid and water

The 1:2:2 triglyme/dichloropicric acid/water adduct is triclinic, space group P ; at 172(2) K, a = 4.9210(10), b = 13.424(3), c = 14.068(3) Å, = 115.04(3), = 90.93(3), = 92.24(3)°, D _x = 1.600(5) g cm^–3, V = 840.8(3) ų, and Z = 1. Each water molecule is hydrogen bonded to a terminal OCH₃ group of one polyether and to an oxygen adjacent to an OCH₃ of a neighboring polyether, resulting in two-dimensional ribbons. These ribbons, in turn, are assembled into a three-dimensional structure held together by chains of dichloropicric acid molecules connected to each other through chlorine–nitro group oxygen intermolecular interactions. The picric acid chains are attached to the water–polyether ribbons by hydrogen bonds from the picric acid to the water. The 1:2:2 tetraglyme/dichloropicric acid/water adduct is monoclinic, space group C2/c; at 172(2) K, a = 30.529(6), b = 5.4210(11), c = 25.413(5) Å, = 122.33(3)°, D _x = 1.597(3) g cm^–3, V = 3553.7(12) ų, and Z = 4. The hydrogen bonding pattern resembles that of the analogous 1:2:2 pentaglyme complex reported previously, with the exception that both of the lone pairs of the central oxygen atom participate in hydrogen bonding to protons of water molecules. The second water proton is hydrogen bonded to a terminal OCH₃ group. In this complex the dichloropicric acid molecules form a two-dimensional layer through chlorine–nitro group oxygen intermolecular interactions. The water molecules bond each isolated polyether molecule to adjacent dichloropicric acid layers. The 1:4:4 nonaglyme/dichloropicric acid/water complex is triclinic, space group P ; at 172(2) K, a = 8.0830(16), b = 13.570(3), c = 16.751(3) Å, = 102.01(3), = 102.39(3), = 96.43(3), D _x = 1.637(6) g cm^–3, V = 1731.5(6), and Z = 1. The hydrogen bonding pattern is similar to that in the pentaglyme complex, except that four dichloropicric acid molecules and four water molecules are coordinated to a single polyether, and the polyether chain is appreciably disordered. In this case there are again chains of dichloropicric acid molecules held together by intermolecular chlorine–oxygen interactions. The chains are packed into two-dimensional layers held together through hydrogen bonds to water. Each isolated polyether is connected to four water molecules, two attached to dichloropicric acid molecules in one layer and the other two connected to the adjacent layer.     

Synthesis and X-ray structure analysis of 2-acetylamino-benzoic acid

The title compound crystallizes in the orthorhombic space group Fdd2 with unit cell parameters a = 10.848(1) Å, b = 30.264(1) Å and c = 10.577(1) Å, V = 3472.47(2) ų, and Z = 4. The final reliability index is 0.030 for 700 observed reflections. Nitrogen of the amide group and carbon atom of the acid group deviate significantly below and above the plane of the phenyl ring. The crystal cohesion is accentuated by N—HO and O—HO hydrogen bonds.     

Near-perfect dipole parallel-alignment in the highly anisotropic crystal structure of 4-iodoacetophenone-(4-methoxyphenylethylidene) hydrazone

The title compound crystallizes in the space group Pna2(1) with cell parameters a = 6.4606(3), b = 7.2155(3) and c = 33.5878(16) Å. The azine shows a gauche conformation about the N—N bond and there is an angle of 58.1° between the benzene rings of each azine. This conformation allows for two intermolecular arene–arene T-contacts between pairs of benzene rings. The characteristic structural motif features T-contact formation between like–substituted arene rings and this architecture results in a highly dipole-parallel aligned lattice. All azines are perfectly colinear within each layer and the orientations of the azines in different layers are nearly the same. The surfaces of the layers exhibit a quadrilateral kite-shaped arrangement of I-atoms and of OCH₃-substituents. The layers pack such that the OCH₃—carbon atoms are placed above the interstices between the I-atoms in the adjacent layer.     

Synthesis,Characterization, Crystal Structure,and Thermal Analysis of 4-[(3-acetylphenyl)amino]-2-methylidene-4-oxobutanoic Acid

4-[(3-Acetylphenyl)amino]-2-methylidene-4-oxobutanoic acid (1) is synthesized by a ring opening reaction of itaconic anhydride with 3-aminoacetophenone and characterized by FT-IR, ¹H NMR, UV-Vis, TGA, DTA, and single crystal X-ray diffraction. The crystal of 1 belongs to triclinic unit cell in the P-1 space group with the unit cell dimensions a = 4.9485(3), b = 5.3614(6), c = 22.457(2) Å, α = 88.295(8), β = 89.379(7), γ = 84.495(7), and Z = 2 The crystal structure is solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0467 for 1623 observed reflections. Intermolecular N&;sbnd;H?…O and O&;sbnd;H?…O hydrogen bonds links the molecules into chains along [010] direction. In addition the thermal stability of the 1 is determined by using DTA, TGA analysis, and wavelength absorption at λ_max = 297 nm is determined by UV-Vis spectrophotometer.     

Synthesis and Crystal Structures of (E)-1-Phenyl-3-[(2,4,6-Trimethylphenyl)]prop-2-En-1-One and (E)-1-Phenyl-3-[(4-Trifluoromethylphenyl)]prop-2-En-1-One

Two chalcone compounds, namely (E)-1-phenyl-3-[(2,4,6-trimethylphenyl)]prop-2-en-1-one (1) and (E)-1-phenyl-3-[(4-trifluoromethylphenyl)]prop-2-en-1-one (2), have been synthesized and structurally characterized by elemental analysis, ¹H NMR spectrum, and single-crystal X-ray diffraction analysis. The chalcone molecules in (1) and (2) have the common skeleton of 1,3-diaryl-2-propen-1-one and adopt an (E)-configuration about the C = C double bonds. In addition, X-ray analysis reveals that the π···π stacking interactions are well observed in the crystal structure of (1) and (2).     

Crystal and molecular structure of 1,2-difluoroethane and 1,2-diiodoethane

A single crystal of phase 1 of 1,2-difluoroethane was grown from the melt directly on an X-ray diffractometer close to the melting point of 169 K. It crystallizes in the monoclinic space group C2/c with lattice parameters a = 7.775(4), b = 4.4973(7), c = 9.024(3) Å, = 101.73(1)°, V = 308.9(2) ų, d _calc = 1.420 g cm^–3 for Z = 4. A second phase of 1,2-difluoroethane was obtained under similar conditions which crystallizes in the orthorhombic space group P2₁2₁2₁ with the unit cell parameters a = 8.0467(16), b = 4.5086(9), c = 8.279(2) Å,V = 300.36(11) ų, d _calc = 1.461 g cm^–3 for Z = 4. In both phases the 1,2-difluoroethane molecules adopt the gauche conformation with F–C–C–F torsion angles close to 68°. Crystals of 1,2-diiodoethane C₂H₄I₂ were grown from pentane at –30°C. A platelet single crystal of the size 0.35 × 0.25 × 0.03 mm was measured with Mo K-radiation at 153 K. 1,2-Diiodoethane crystallizes in the monoclinic space group P2₁/n with a unit cell of a = 4.6051(7), b = 12.939(2), c = 4.7318(7) Å, = 104.636(3)°, V = 272.79(7) ų, Z = 2, d _calc = 3.431 g cm^–3, (MoK) = 11.353 mm^–1. In the molecule the two neighboring iodine atoms are positioned anti. The shortest intermolecular contacts occur via iodine–iodine interactions resulting in layers of molecules in the crystal.     

Synthesis,characterization, and crystal structure analysis of 2-(2-hydroxy-3-methoxyphenyl)-1-(4-chlorophenyl)-4,5-diphenyl-1h-imidazole

The substituted imidazole C₂₈H₂₁ClN₂O₂, was prepared via multicomponent reactions and the product crystallized using dimethylformamide. The structure of the compound was established by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, UV-visible, proton nuclear magnetic resonance spectroscopy, and single-crystal X-ray diffraction. The molecule is crystallized in the tetragonal crystal system with the space group P4₃2₁2 and with unit cell parameters a = 12.246(4) Å, b = 12.246(4) Å, c = 31.781(2) Å, and Z = 8. The molecular and crystal structures of the title molecule are stabilized by the intramolecular interactions, O-H···N and C-H···N, and intermolecular interaction, C-H···O.     

Structure and properties of lithium thio-boro-germanate glasses

Structural studies of the ternary xLi₂S + (1 − x)[0.5B₂S₃ + 0.5GeS₂] glasses using IR, Raman, and ¹¹B NMR show that the Li₂S is not shared proportionately between the GeS₂ and B₂S₃ sub-networks of the glass. The IR spectra indicate that the B₂S₃ glass network is under-doped in comparison to the corresponding composition in the xLi₂S + (1 − x)B₂S₃ binary system. Additionally, the Raman spectra show that the GeS₂ glass network is over-modified. Surprisingly, however, the ¹¹Boron static NMR gives evidence that ∼80% of the boron atoms are in tetrahedral coordinated. A super macro tetrahedron, B₁₀S₁₈⁻⁶ is proposed as one of the structures in these glasses in which can account for the apparent low fraction of Li₂S present in the B₂S₃ sub-network while at the same time enabling the high fraction of tetrahedral borons in the glass.     

Copper redox behavior, structure and properties of copper lead borate glasses

Copper oxidation states, structure and properties of xCuO · (50-x)PbO · 50B₂O₃ glasses were investigated. Both infrared (IR) and ¹¹B magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies were employed to determine the tetrahedral BO₄ fraction in the glasses as a function of CuO content. IR study indicates that the replacement of Pb²⁺ by Cu²⁺ ions increases the BO₃ units by converting BO₄- containing groups into ring type metaborate groups. The oxidation states of copper ions in the glasses have been studied using both X-ray photoelectron spectroscopy (XPS) and the wet chemical method. For high CuO containing (?30 mol%) glasses, high Cu⁺ ion concentrations (Cu⁺/Cu_tot.>0.3) result in a relatively slow disproportionation of B⁴-containing groups because of the small coordination number of Cu⁺ compared to Cu²⁺ ions. Effects of both glass structure and redox states of copper ions on glass properties including density, Vickers’ hardness, coefficient of thermal expansion, and chemical durability have been discussed.     

The crystal and molecular structure of (−)—Crinine (C16H17NO3)

(–)—Crinine, C₁₆H₁₇NO₃, is an alkaloid extracted from the bulbs of Pancratium maritimum L. (Amaryllidaceae). The compound crystallizes in the space group P2₁2₁2₁ with cell dimensions a = 6.040(1), b = 12.382(1), c = 17.861(2) Å, with Z = 4. The molecule has five rings and an OH group. The N-containing, five-membered ring and the D ring have envelope conformations. The A and B rings have distorted chair and half-chair conformations, respectively.     

Deviations from square-root distributions of electronic states in hydrogenated amorphous silicon and their impact upon the resultant optical properties

We study the distributions of conduction band and valence band electronic states associated with hydrogenated amorphous silicon. We find that there are substantial deviations from square-root distributions, particularly deep within the bands and within the gap region. The impact of these deviations is assessed through a determination of the spectral dependence of both the joint density of states function and the imaginary part of the dielectric function. These deviations are found to have a considerable effect upon the determination of the corresponding Tauc optical gap, the optical gap obtained for the case of hydrogenated amorphous silicon being 220 meV lower than the energy difference between the valence band and conduction band band edges. We suggest that the standard interpretation for the Tauc optical gap, as the energy difference between these band edges, should be reconsidered in light of these results.     

Indium content determination related with structural and optical properties of InGaN layers

We studied the structural and optical properties of a set of nominally undoped epitaxial single layers of In_xGa_1−xN (0<x0.2) grown by MOCVD on top of GaN/Al₂O₃ substrates. A comparison of composition values obtained for thin (tens of nanometers) and thick (≈0.5 μm) layers by different analytical methods was performed. It is shown that the indium mole fraction determined by X-ray diffraction, measuring only one lattice parameter strongly depend on the assumptions made about strain, usually full relaxation or pseudomorphic growth. The results attained under such approximations are compared with the value of indium content derived from Rutherford backscattering spectrometry (RBS). It is shown that significant inaccuracies may arise when strain in In_xGa_1−xN/GaN heterostructures is not properly taken into account. Interpretation of these findings, together with the different criteria used to define the optical bandgap of In_xGa_1−xN layers, may explain the wide dispersion of bowing parameters found in the literature. Our results indicate a linear, E_g(x)=3.42−3.86x eV (x0.2), “anomalous” dependence of the optical bandgap at room temperature with In content for In_xGa_1−xN single layers.     

The structural transformation and properties of spin-on poly(silsesquioxane) films by thermal curing

In this study, the structural transformation and properties of five commercially available poly(silsesquioxanes) by thermal curing were investigated, including poly(hydrogen silsesquioxanes) (HSQ and T12), and poly(methylsilsesquioxanes) (MSQ, T7 and T9). These materials with a different cage/network ratio and side groups (Si-H and Si-CH₃). The FTIR spectra show that the poly(silsesquioxane) films have different contents of the Si-O-Si cage and network structures, which significantly affects the refractive index and dielectric constant. The shifting of the Si-O-Si network band in the FTIR spectra can be correlated with their molecular structures. The refractive indices and dielectric constants of the studied poly(silsesquioxane) films increase with increasing the Si-O-Si network content. The retention of the Si-H or Si-CH₃ side group suggests the existence of the cage structures in the poly(silsesquioxane) films. The Si-O-Si cage structure results in a larger free volume than the Si-O-Si network structure in the poly(silsesquioxane) films and thus reduces the refractive index and dielectric constant. It is supported by the porosity result. The order of the refractive index in the studied poly(silsesquioxanes) films is T12>HSQ for the Si-H side group and T7>T9>MSQ with the Si-CH₃ side group, which can be correlated with the Si-O-Si network content. The poly(silsesquioxane) film with the Si-CH₃ side group has a lower refractive index than the Si-H side group at the same Si-O-Si network content, which is probably due to the steric hindrance effect of the CH₃ group.     

Preparation and optical properties of titania-doped hybrid polymer via anhydrous sol-gel process

Incorporation of metal alkoxides (Ti, Zr, etc.) for tuning the optical properties of silica glasses by the sol-gel process is of significant interest for optical applications. In this paper, we report an anhydrous sol-gel process for preparation of photosensitive titania-doped hybrid glassy polymer with good homogeneity and high doping concentration (TiO₂ up to 40 mol%). The process consists of two steps: in the first step methacryloxypropyltrimethoxysilane (MPS) is hydrolyzed by boric acid through ligand exchange reaction (OH↔OR) under anhydrous conditions; and in the second step dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPhDMS) and titanium ethoxide (TET) were added to condense with the silanols formed in the first step. The optical properties of the synthesized hybrid polymer were studied, and results showed that the hybrid material has low OH absorption, low optical losses (0.45 dB/cm at 1550 nm and 0.16 dB/cm at 1310 nm respectively), and good thermo-optical linearity with tuneable refractive index. The effect of TiO₂ doping in reducing the OH concentration of the hybrid material was observed, and the mechanism for this effect is discussed.     

Preparation and properties of silica films with higher-alkyl groups

Silica films with various types of alkyl groups were grown from the liquid phase, at room temperature, using alkyl tri-alkoxy silane compounds. From Fourier transform infrared (FTIR) absorption measurements, a majority of Si-alkyl bonds in the source molecules were found to remain in the grown film, while Si-alkoxy bonds were completely removed. Electrical and thermal properties have been measured comparatively for various films having dense alkyl groups. The films with the methyl group are promising for silicon production in ultra large-scale integrated circuits (Si-ULSIs) and the film having the vinyl group for non-heat-tolerant compound-semiconductor large-scale integrated circuits (LSIs).     

Soft organic and metal-organic frameworks with porous architecture: From wheel-and-axle to ladder-and-platform design of host molecules

The family of wheel-and-axle host molecules is reviewed and the approaches to the creation of new host geometries for supramolecular materials based on weaker interactions are discussed. The combination of bulky groups (or platforms) and spacers yields various host geometries including humming-top molecules (Werner complexes, metal dibenzoylmethanates and other bis-chelates, dimeric metal carboxylates and macrocyclic complexes), wheel-and-axle and dumb-bell shaped molecules and their modifications, ladder-and-platform, shish-kebab, multi-decker, stair-case and double-strand ladder-and-platform oligomeric and polymeric structures. The host shapes are compared with cyclic and trifoil (trityl) host types. The use of metal centers, chelating and macrocyclic ligands (β-diketones, carboxylic acids, Schiff bases, porphyrins, phthalocyanines, corroles, annulenes and their analogs), bridging ditopic ligands and other building elements in the engineering of host molecules is illustrated. The role of such factors as size and nuclearity of the platforms, rigidity/flexibility of the spacers and hydrogen bonding is discussed. The relation between porosity and packing efficiency, predisposition to self-inclusion, parallel alignment and interdigitation, dimensionality and secondary assembly of host molecules in the crystal is examined. Clathration and sorption abilities and other important qualities and functionalities of the new host materials are elucidated.     

Influence of additives and post-synthesis treatment on the structural properties of sol-gel prepared alumina-doped zirconia studied by EXAFS-spectroscopy and X-ray diffraction

Alumina- (5 and 10 wt%) doped zirconia samples were prepared by sol-gel processing of aluminum sec-butoxide and zirconium butoxide in the presence of acids (acetic, sulfuric or nitric acid) or organic additives (Pluronic P123). X-ray absorption spectroscopy, X-ray diffraction and nitrogen adsorption experiments showed that the structure of the synthesized mixed oxides is strongly influenced by the chemical synthesis parameters.     

Structure and properties of transition metal complexes of naphthoquinonedithiolate

Naphthoquinonedithiolate (nqdt) is a noninnocent ligand forming dithiolene transition metal complexes. Most [M(nqdt)₂]^–1 and [M(nqdt)₂]^–2 complex ions are planar with each forming an isomorphous series with the (n-butyl)₄N⁺ (tba) counter ion. The cobalt complex is isolated as a step dimer (tba)₂[Co(nqdt)2]₂ where two square-planar monomer units are bonded via Co–S intermolecular interactions.Ab initio andsemi-empirical calculations are used to investigate the complex ions. The complexes form tba single crystals only with difficulty, and an extensive study with ions of various shapes and charges failed to identify a more satisfactory counter ion. The magnetic susceptibilities of four complexes are discussed. The (tba)[Ni(nqdt)₂] complex undergoes a weak ferromagnetic transition at 4.43 K while a mixed oxidation state Mn(II) complex exhibits a weak ferromagnetic transition at 40K. The crystal structures of (tba) [Cu(nqdt)₂], (tba)[Ni(nqdt)₂], (tba)₂[Ni(nqdt)₂], (tba)₂[Pd(nqdt)₂], {(tba)[Co(nqdt)₂]}₂ and four side reaction products 5,7,12,14-tetrahydrodibenzo-[b,i]thianthrene-5,7,12,14-tetraone (2), benzocyclohexa-2,5-diene-1,4-dione-1,3-thiole-2-thione (3), a thiomethyl derivative (4), and an unusual oxidatively coupled product (5) are reported.