Structural and Photophysical Properties of a Cd(II) Coordination Polymer Based on Mixed Aromatic Ligands: A Combined Experimental and Theoretical Study

A novel one-dimensional Cd(II) coordination polymer (CP) based on mixed aromatic ligands was synthesized and characterized by X-ray diffraction, thermogravimetric analysis and spectroscopic analyses. Fingerprint plots in Hirshfeld surface analysis illustrate that the one-dimensional crystal structure of the CP is stabilized by C–H···O, π···π, C–H···π, and H···H intermolecular interactions. The structural and photophysical properties of the CP were then investigated by time-dependent density functional theory methods, and computational results well reproduced the experimental data. The combined investigations found a ligand-to-ligand charge transfer character during the electrons relax from the first singlet excited₁ state of the CP. The weak fluorescence of CP could be resulted from the energy interlacing of the frontier molecular orbitals (FMOs) of aromatic ligands and the fulfilled d ¹⁰ configuration of Cd(II). Herein, this CP exhibits as a potential tunable luminescent sensor by adjusting the energy levels of the FMOs of aromatic ligands.     

Synthesis,crystal structures and non-bonded S···S contacts with O‒H···O/O‒H···S hydrogen bonds in isomeric hydroxyphenyl-1,3-dithianes

The synthesis of isomeric hydroxyphenyl-1,3-dithianes and the role of sulfur in them to generate different engineered solids based on non-bonded O···S contacts and O?H···S hydrogen bonds are presented. With an increasing number of OH groups and dithiane rings (e.g. 2, 3), the role of O?H···S interactions becomes less prominent and the strong O?H···O hydrogen bonds along with C?H···π and π–π stacking interactions dominate the packing arrangement of the hydroxyphenyl-1,3-dithianes.     

Synthesis and structure of an unprecedented supramolecular bridged-hydroxyl manganese(III)-lithium(I) coordination polymer [MnIIIL(OH)2LiI]n through both intermolecular hydrogen bonds and π–π stacking interactions

An unprecedented linear supramolecular manganese(III)-lithium(I) coordination polymer, [Mn^IIIL(OH)₂Li^I]_n, has been prepared and structurally characterized. The polymer is a one-dimensional infinite Mn(III)–O–Li(I) chain supramolecular structure formed by intermolecular O–H···O and O–H···Cl hydrogen bonds and π–π stacking of neighboring benzene rings.     

Effect of functionlization of N,N-dibenzyldithiocarbamate: synthesis,spectral and structural studies on bis(N-benzyl-N-(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) and bis(N-benzyl-N-(4-cholrobenzyl)dithiocarbamato-S,S′)cadmium(II) and their use for the preparation of MS (M = Zn,Cd)

Bis(N-benzyl-N-(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) (1) and bis(N-benzyl-N-(4-chlorobenzyl)dithiocarbamato-S,S′)cadmium(II) (2) have been prepared and characterized by elemental analysis, IR and NMR (¹H and ¹³C) spectroscopy and single-crystal X-ray analysis. Complexes 1 and 2 exist as monomer and dimer, respectively. Crystal structures of 1 and 2 confirm the presence of four coordinated zinc in a distorted tetrahedral arrangement and five coordinated cadmium in a distorted square pyramid arrangement, respectively. Both the complexes are further stabilized by various interactions such as C–H···S, C–H···N, C–H···O and C–H···π (chelate). C–H···O interaction leads to the formation of dimer in complex 1. In complex 2, C–H···π (chelate) interaction runs in opposite directions which results in the polymeric chain. ZnS and CdS have been prepared from 1 and 2, respectively, and characterized by powder X-ray diffraction, SEM, UV–Vis and fluorescence spectroscopy. The X-ray diffraction pattern confirms the wurtzite phase of as-prepared ZnS and CdS.     

X‐ray crystal structure analysis for CI Disperse Orange 61

The synthesis, crystal structure analysis and characterisation of a monoazo dye, CI Disperse Orange 61, are reported. The dye crystallised in the triclinic system, space group P‐1 with a = 8.859(2), b = 9.899(2), c = 11.417(3)Å, α = 78.51(4)°, β = 70.37(3)°, γ = 80.46(4)°, V = 918.8(4)ų and Z = 2. There is only one molecule in the asymmetric unit. The two phenyl rings are oriented at a dihedral angle of 57.87(20)°. In the crystal structure, intermolecular C–H…N hydrogen bonds link the molecules into centrosymmetric dimers, forming R₂²(30) ring motifs, in which they may be effective in the stabilisation of the structure. The π…π stacking (interactions) between the phenyl rings may further stabilise the structure, with a centroid–centroid distance of 3.741(4)Å.     

X-ray crystal structure of the dye 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene

The crystal structure and molecular conformation of 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene (C₁₇H₁₇N₄Br, mol. wt. = 357·2 a.m.u) has been determined from X-ray diffraction data; triclinic, P$\text{1}$ (No. 2), a = 10·132(11) Å, b = 12·216(16) Å, c = 6·966(11) Å, α = 104·21(9)°, β = 92·67(12)°, γ = 97·22(7)°, V = 826·5(9) ų, Z = 2, D_c = 1·436 g cm^?3, F(000) = 378, λ(MoKα) = 0·71069 Å, μ(MoKα) = 26·0 cm^?1. The structure was solved by the multiple solution direct method and refined by full-matrix least-squares to R = 0·059 for 1538 independent observed reflections. The azobenzene skeleton is planar to within 0·06 Å. Most significant bonding data are: NN, 1·290(8) Å; BrC, 1·866(6) Å; mean CN (azo) 1·380(8) Å; NNC, 113·6(4) and 115·3(4)°; NCC (cis relative to NN) 125·9(4)° and 126·7(4)°; NCC (trans) 116·8°(5)° and 116·1(4)°.     

X-ray crystal structure of the dye 2-bromo-4-cyano-4′-N,N-diethylaminoazobenzene

The crystal structure of 2-bromo-4-cyano-4′-N,N-diethylaminoazobenzene has been determined from X-ray diffraction data: C₁₇H₁₇N₄Br, mol. wt = 357·1. Triclinic, Pī (No. 2), α = 13·162(5) Å, b = 7·516(3) Å, c = 8·496(4) Å, α = 101·63(4)°, β = 95·79(4)°, γ = 91·49(4)°, V = 818·10 ų, Z = 2, D_c = 1·45 g cm^?3, F(000) = 378, λ(Mo_Kz) = 0·7107 Å, μ(Mo_Kα) = 26·70 cm^?1. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0·053 for 2081 independent reflexions. The molecule possesses an essentially planar azobenzene skeleton. The effects of substituents on the geometry of the azo group are discussed. Significant molecular parameters are: NN, 1·264(6) Å; ₁BrC, 1·904(5) Å; mean NC, 1·410(7) Å; NNC, 115·7(2)° and 113·0(2)°; NCC (cis relative to NN), 125·4(3)° and 123·1(2)°; CC(Br)C, 123·0(2)°.     

Preparation,Infra-red,MAS-NMR and Structural Characterization of a New Copper Based Inorganic–Organic Hybrid Compound: [C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>Cl]<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>

The ionic salt [2(C₅H₆N₂Cl)⁺], [CuCl₄]^2? complex of copper(II) has been synthesized and characterized. The X-ray diffraction analysis with a single crystal of this compound showed that the title compound (4-amino-2-chloropyridinium)₂CuCl₄ [(CAP)₂CuCl₄], crystallized at room temperature in the monoclinic system, space group C_2/c (N°.15) and the following : a = 16.0064 (2) Å; b = 7.7964 (10) Å; c = 14.7240 (2) Å; β = 102.497 (10)°; V = 1793.91 (4) ų and Z = 4. The structure was solved by using 1,589 independent reflections down to R value of 0.021. The unit cell is made up of tetrachlorocuprate(II) anions and 4-amino-2-chloropyridinium cations linked together by an extensive hydrogen bond network of types N–H···Cl (N: pyridinium) and N–H···Cl (N: amine), and cation-lone pair of nitrogen element interactions. Solid state NMR spectra showed one and five isotropic resonances, ⁶³Cu and ¹³C, respectively, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new copper(II) based organic–inorganic hybrid and the conductivity properties that these compounds exhibit.     

Studies of the development of fibrillar structure in nylon 6

Very thin films of poly(vinyl alcohol) could be prepared by utilizing the adsorption of polymer molecules at air/water interface from the aqueous solutions of the poly(vinyl alcohol) derived from vinyl trifluoroacetate. The films prepared by the bubble method were thinner than those obtained by the frame method. The minimum thickness of the former films was 260 Å and that of the latter was 1800 Å. These very thin films resisted water at temperatures below 55°C. The maximum Young's modulus of the drawn/annealed films prepared from these samples was 30 GPa. The permeability of water, J_w/δP, was 2–6 × 10^?3 cm · s^?1 atm^?1 (0–55°C) for the untreated film (thickness: 1800 Å) prepared by the frame method and 0.8–2.2 × 10^?2cm · s^?1 · atm^?1 (5–55°C) for the untreated film (360 Å) prepared by the bubble method, and depended on the thickness of film.     

Exploration of Intermolecular Interaction of One Silver(I) Polymer with Bis(pyrazolyl)methane Derivative: Experimental Observations,Hirshfeld Surface Analyses and Fluorescent Properties

In the superbasic medium DMSO-KOH, bis(3,3-diethoxycarbonyl-1-pyrazolyl)methane (L) was synthesized. Besides, the single crystal of L has been obtained. Meanwhile, one novel coordination polymers, [Ag(L)(NO₃)] _n (1) was successfully prepared. The single X-ray diffraction data reveal that L crystallized in the P-1 space group. Novel bis(pyrazolyl)methane derivative ligand, L acts as multidentate ligands to coordinate with Ag ion to form a six-membered boat conformation. And furthermore the nitrate groups bridge each Ag(I) to construct a zigzag chain. The fluorescent properties of the complex were examined in solution and compared with the ligand. In order to investigate the intermolecular interactions, we also studied Hirshfeld surface analysis of ligand and the complex. The Hirshfeld surface analysis reveals that the main intermolecular interactions are H···H and O···H/H···O interactions which comprise 23.9 and 33.8 % of the total Hirshfeld surface area.     

Studies on polycrystalline layered ceramic oxide: LiFeVO4

Abstract

A new polycrystalline layered ceramic oxide, LiFeVO₄, has been prepared by a standard solid state reaction technique. The preparation conditions were optimised using thermogravimmetric analysis (TGA) technique. Material formation under the reported conditions was confirmed by X-ray diffraction studies. A preliminary structural analysis indicated that the crystal structure was orthorhombic with lattice parameters: a=4·3368 Å, b=13·1119 Å and c=16·3426 Å. The phase morphology and surface property were studied by scanning electron microscopy. Complex impedance analysis of the sample indicated bulk contribution to electrical properties at T≤125°C, grain boundary effects at the temperatures ≥125°C, negative temperature coefficient of resistance (NTCR) effect and evidence of temperature dependent electrical relaxation phenomena in the sample. The dc conductivity σ_dc shows typical Arrhenius behaviour when observed as a function of temperature. The activation energy value was estimated to be 0·24 eV. The value of σ_dc, evaluated from complex impedance spectrum, shows a jump of nearly two orders of magnitude at higher temperature (～1·24 × 10^?5 S cm^?1 at 350°C) when compared with that of σ_dc (1·14 × 10^?6 S cm^?1 at 50°C). Alternating current conductivity spectrum obeys Jonscher's universal power law. The results of σ_ac v. temperature are also discussed.     

Synthesis,crystal structure and desulfurization properties of zig-zag 1D coordination polymer of copper(II) containing 4-methoxybenzoic acid ligand

ABSTRACT

Combustion of fuels containing organosulfur compounds has resulted in the emission of sulfur oxides (SO_x) into the atmosphere, therefore, causing serious environmental and health hazards. Herein, slightly distorted octahedral zig-zag 1D coordination polymer of copper(II) [Cu(4-mba)₂(H₂O)₃] was synthesized by reacting copper sulfate pentahydrate with a carboxylate-containing ligand (H-4mba?=?4-methoxybenzoic acid) and employed for sulfur compound uptake. The ligand coordinates to the copper(II) atom via two pairs of deprotonated ligating atoms (carboxylate oxygens) and two water molecules. Structural characterization also reveals that interplay of O–H···O, N–H···O, C-H···O and C–H···π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three-dimensional supramolecular assembly. The complex, [Cu(4-mba)₂(H₂O)₃], show potential for desulfurization of fuel with an observed adsorption capacity of 9.6?mg/g at 32°C for 6?h. DFT calculations further revealed a transfer of electron sulfur-containing compounds and the complex, [Cu(4-mba)₂(H₂O)₃], thus leading to a stronger pi–pi interaction.     

Synthesis,Characterization, Crystal Structures and Thermal and Fluorescence Studies of Dinuclear and Polymeric Silver(I) Complexes of 5,5-Diethylbarbiturate with 2,5-Dimethylpyrazine and Piperazine Involving Ag–Ag Interactions

Two silver(I) complexes, [Ag(dmpyz)₂][Ag(barb)₂] (1) and {[Ag(ppz)][Ag(barb)₂]·H₂O} _n (2) (barb = 5,5-diethylbarbiturate, dmpyz = 2,5-dimethylpyrazine and ppz = piperazine), have been synthesized and characterized by elemental analyses, IR, thermal analysis (TG-DTA) and single-crystal X-ray diffraction. Complex 1 consists of [Ag(dmpyz)₂]⁺ and [Ag(barb)₂]^? ions in which the silver(I) ions are linearly coordinated by two dmpyz or two barb ligands. These two ions are connected by strong Ag–Ag interactions (Ag–Ag = 2.896 (1) Å). Complex 2 is a 1D coordination polymer in which the silver(I) ions are bridged by the ppz ligands in a linear fashion, leading to a zigzag chain of [Ag(ppz)] _n ⁺ , which interacts with the [Ag(barb)₂]^? units by Ag–Ag interactions of 3.183 (1) Å. The 1D chains are further assembled to form 3D networks by strong N–H···O and OW–H···O hydrogen bonds. IR spectra and TG-DTA data are in agreement with the crystal structures. The fluorescent properties of 1 were also evaluated.     

Lactose hydrolyzed milk powder: Thermodynamic characterization of the drying process

Industrial production of lactose hydrolyzed milk powder (LHMP) remains challenging. Due to the presence of the monosaccharides glucose and galactose, lactose-free powders tend to suffer stickiness, caking, and browning during drying and storage. We sought to find ideal conditions spray dryer inlet air temperature (θ_air,in) and concentrated milk flow rate (m_CM) for LHMP production. We tested θ_air,in settings of 115–160°C and m_CM of 0.3–1.5?kg?·?h^?1, and also applied mass and energetic balances. LHMP generally exhibited higher mass and energetic losses than the control (milk powder containing lactose), as a consequence of the relatively low dryability of LHMP. For a lab scale spray dryer, the ideal conditions settings for LHMP production were θ_air,in?=?145?±?2°C and m_CM?=?1.0?kg?·?h^?1, taking into account the mass yield and energetic cost (kJ?·?kg^?1 of powder) of the process. These ideal conditions are a potential tool for the industrial development of lactose-free dairy powders.     

Synthesis,crystal structure,and optical property of a one-dimensional selenidostannate: [AEPPH2]2[Sn5Se12] (AEPP = N-aminoethylpiperazine)

A one-dimensional (1-D) selenidostannate, [AEPPH₂]₂[Sn₅Se₁₂] (AEPP = N-aminoethylpiperazine) (1), has been prepared under solvothermal condition and characterized. Single crystal X-ray analysis reveals that compound 1 crystallizes in the triclinic space group P-1, a = 10.6351(7) Å, b = 10.6850(7) Å, c = 10.7771(7) Å, α = 61.3440(10)°, β = 62.4420(10)°, γ = 67.4680(10). With distinct linkage modes between SnSe₄ tetrahedrons and SnSe₆ octahedrons, a secondary building unit (SBU) [Sn₅Se₁₄] is formed. Compound 1 contains infinite bead-like chains built up by the [Sn₅Se₁₄] SBUs, and the protonated [AEPPH₂]^2 + cations are located between the chain spaces. A pseudo 3-D network is formed through C–H···Se and N–H···Se hydrogen bonds between adjacent chains. Its optical property and theoretical band structure and density of state (DOS) calculations have also been studied.     

Stereochemische Untersuchungen heterocyclischer Verbindungen. XII. Kristall- und Molekülstruktur von 1-(2-Amino-1-cyano-2-thio-ethylen)pyridiniumyliden

Stereochemical Investigations of Heterocyclic Compounds. XII. Structural Investigations of 1-(2-Amino-1-cyano-2-thio)ethene Pyridinium Ylides Two isomerization processes were found by ¹H-d-n. m. r. characterized by ΔG^* = 67 ± 4 KJ/mol for E- Z-isomerization and ΔG^* = 46 ± 5 KJ/mol for the hindered rotation of the pyridine substituent in 1a . The structure of 1b was solved by direct method. Crystals are monoclinic space group P2₁/n, a = 13.682(3), b = 9.452(1), C = 19.713(6) Å, β = 96.42(2)°, V = 2533.3 ų, D_x = 1.328 Mg · m⁻³, Z = 8. Both E- and Z-isomeres of 2b are found in the crystal lattice. The amino C distance with 1.369 (1,387) Å is shorter than the theoretical single bond distance. The formal  CC double bond with 1.377 (1.391) Å is considerably longer than 1.337 Å observed in the some alkenes.     

Structure of the dye 2,6-dichloro-4′-N,N-diethylaminoazobenzene

The structure of 2,6-dichloro-4′-N,N-diethylaminoazobenzene has been determined from X-ray diffractometer data: C₁₆H₁₇Cl₂N₃, MW = 322·2, monoclinic, P2₁/n, a = 11·160 (2), b = 12·066 (2), c = 13·633 (3) Å, β = 116·46 (2)°, V = 1643·5 ų, Z = 4, D_c = 1·30 g cm^?3, F(000) = 672, λ(MoKα) = 0·71069 Å, μ(MoKα) = 3·94 cm^?1. The structure was solved by direct methods and refined to R = 0·073 for 1495 independent reflexions. The molecule is non-planar with a dihedral angle of 87·8° between the phenyl rings. The effects of substituents on the aromatic ring geometry are discussed. Significant molecular parameters are: NN, 1·164 (9) Å; mean ClC, 1·741 (6) Å; mean CN(azo), 1·487 (9) Å; NNC, 112·4 (2)° and 109·1 (2)°; NCC (cis relative to NN), 125·5 (3)° and 122·4 (2)°; NCC (trans relative to NN) 114·0 (3)° and 119·5 (3)°; mean CC(Cl)C, 122·3 (3)°.     

Phase structure and electrical properties of lead free Na0·5Bi0·5TiO3–CaTiO3 ceramics

Abstract

Abstract

(1?x)Na_0·5Bi_0·5TiO_3?xCaTiO₃ ceramics with x?=?0–0·2 were prepared by solid state sintering method. Structural and morphology studies carried out by X-ray diffraction and scanning electron microscopy indicate the change in crystal structure from rhombohedral to orthorhombic symmetry (R3C to Pnma). The morphotropic phase boundary of this system was found to lie around x?=?0·08–0·14, where the orthorhombic and rhombohedral symmetries coexist. The orthorhombic phase is stabilised for x>0·14, indicating that the rhombohedral phase of Na_0·5Bi_0·5TiO₃ is susceptible to orthorhombic distortion brought about by Ca substitution. Calcium substitution in Na_0·5Bi_0·5TiO₃ caused an obvious decrease in peak temperature and a decrease in relative permittivity. The compositional variation of the fundamental dielectric behaviour is discussed in relation to the crystal chemistry of the system. The highest piezoelectric constant d₃₃ of 85 pC N^?1 is achieved for x?=?0·1, with the coercive field of 18 kV cm^?1 and the dielectric maximum temperature of 148°C.     

Azo—hydrazone tautomerism in azo dyes. III. The tautomeric structure of 1-(4′-nitrophenylazo)-2-naphthylamine from crystal structure determination

The structure of 1(NO₂)—dioxane 2:1 solvate single crystal has been determined by direct methods and refined by analysis of the three-dimensional Mo Kα intensity data. The unit cell is monoclinic, space group P2₁/c with a = 8·960(3), b = 6·386(2), c = 30·141(11) Å, β = 108·56(2)°. Least-squares refinement of all positional and thermal parameters (hydrogen atoms isotropic) with 1458 independent reflections out of 2817 gave a final R-index of 0·069. The dye molecule is almost planar and of trans configuration. The nitro group, however, is significantly twisted out of the molecular best plane. Six-membered chelate ring structures are formed by intramolecular NH···N bonds while intermolecular NH···O interactions give rise to complex formation involving two dye and one dioxane molecules in a centrosymmetrical arrangement. Two such complexes are accommodated in the unit cell.Based on the observed molecular geometry and quantum chemical (SCF—MO) calculation of bond dimensions a strong predominance of the azo tautomer was concluded for 1(NO₂). This assignment is further supported by empirical correlations, using CN and NN bond distances from a great variety of reported azo and hydrazone structures which are compiled here for the first time. The mobile hydrogen is attached to the amine nitrogen [R(NH) = 1·04(5) Å] thereby excluding a major participation of the hydrazone form. These findings compare well with those for solutions and are in accordance with previous quantum chemical predictions.