Structures of two ketals derived from a pentacyclic cage diketone

The structure of a compound derived from a symmetrical cage diketone in which one of the ketone C=O groups has been converted into a ketal is reported. An investigation into reasons for the selective functionalization resulted in the isolation of acis, cisoid, cis linear triquinane derivative in which both ketones are converted to ketals that share a transannular oxygen atom. Crystal data:2, monoclinic,P2₁/c,a=7.6298(9),b=7.673(3),c=22.125(3)Å,=97.59(1)°,V=1283.9(5)ų, andR=0.048 (1001 reflections);4, triclinic,P¯1,a=7.3864(9),b=9.6362(9),c=10.3889(9)Å,=75.749(6),=76.300(8), =83.100(8)°,V=694.8(4)ų, andR=0.088 (1284 reflections).     

Synthesis and characterization of some novel liquid crystalline compounds of 1,3,4-oxadiazoline and their hydrazone derivatives

Three new series of mesogens have been synthesized by fixing 4-methoxy or 4-butoxy substituted phenyl ring in one side and 4-hydroxy, bromo or amino substituted phenyl group in the other side with different central linkage. The molecular structure of these series was confirmed by elemental analysis and FTIR and ¹HNMR spectroscopy. The mesomorphic properties were studied by using differential scanning calorimetry (DSC) and optical polarizing microscopy (OPM). All the compounds of series [I] exhibit enantiotropic smectic B (SmB) phase. All the compounds of series [II] and [III] display SmB and nematic (N) phases. The mesomorphic properties were found to be dependent on the two terminal 4-substituted phenyl groups and the central linkage group.     

Synthesis,spectroscopic characterization,and crystal structure of a novel indoline derivative

A new indoline derivative, tert-butyl 2′-amino-3′-cyano-6′-methyl-2-oxospiro[indoline-3,4′-pyran]-5′-carboxylate is eco-friendly synthesized, and its spectral properties and X-ray crystal structure are studied. In the molecule, the oxindole and pyran moieties are perpendicular to each other. The crystal structure is stabilized by intermolecular N?H···O and intramolecular C?H···O hydrogen bonds. Centrosymmetric dimer units are formed by intermolecular N?H···O hydrogen bonds. In addition, one C?H···π interaction is also observed.     

Synthesis and characterization of 3C–SiC nanowires

Silicon carbide nanowires have been synthesized by carbothermal reduction, from carbon monoxide and single crystal silicon. Transmission electron microscopy and cathodoluminescence studies confirm the growth of a cubic β-SiC core, coated with an amorphous oxide shell. Planar defects, as stacking faults and rotational twins, are present on (1 1 1) planes. The formation of short thick rods or long thin wires, depending on the growth temperature and time, is discussed.     

Mesomorphic study of novel chalconyl-ester-based nonisomeric series: Synthesis and characterization

Liquid-crystalline elastomers (LCEs) possess large and equilibrium reversible anisotropic dimensional change in response to applied stimuli. The deformation behavior demonstrated by current LCE materials under the stimuli are generally determined by their own geometries and the alignment distributions of liquid crystal (LC) units in the LCE matrices. Here we report a LCE whose synthesis was through a two-stage crosslinking coupled with a mechanical reshaping process, where the shape was mechanically reset before the final crosslinking. It demonstrated reversible memory and change between the initial geometries formed during the first crosslinking stage and any reshaped geometries under the stimuli. Its deformation is not influenced by the geometries and the alignment distributions of LC units in the LCE matrix. This characteristic in LCEs holds promise in a wide range of application researches requiring sophisticated functions and smart structures.     

Synthesis and structural characterization of a novel polymeric praseodymium(III) complex with a new flexible double betaine

A novel polymeric Pr(III) complex with a new double betaine, namely [{Pr(L¹)_1.5(H₂O)₂} _n ][ClOli4]3 _n ·nH₂O (1) (L¹ = 1,4-diazoniobicyclo[2,2,2]octane-1,4-dipropionate), has been synthesized and characterized by X-ray analysis. In the title complex, the Pr(III) atom is nine-coordinated by seven oxygen atoms from five L¹ ligands and two aqua ligands. Each pair of adjacent praseodymium(III) atoms is linked by a pair of ³ chelating and bridging carboxylate groups, thus forming an infinite metal···metal chain running parallel to the a direction, and such chains are cross-linked by flexible backbones of L¹ ligands into a three-dimensional network with the perchlorate anions and lattice water molecules accommodated in the interstitial space. The title complex crystallizes in the monoclinic space group P2₁/n with a = 8.085(2), b = 14.316(3), c = 29.775(6) Å, = 103.04(3)° and Z = 4.     

Synthesis,characterization and crystal structure of a novel 2D Ni(II) complex with malate

An exploration of the nickel‐ malate‐bpa system under hydrothermal conditions, has led to the isolation of a novel framework {[Ni(Hmal)(bpa)]·2.5H₂O}_n ( 1 ) (Hmal = malate dianion, bpa = 1,2‐bi(4‐pyridyl)ethane). Single‐crystal X‐ray analyses reveal that it crystallizes in the orthorhombic space group Fdd2. a = 21.9944(13) Å, b =33.3369(19) Å, c = 10.3969(5) Å, β = 90°. The Ni^II ions are linked into an extended helical chain via Hmal molecules. Further these chains are united together through the bridging bpa to form a 2D grid layer, which exhibits a typical (6,3) topological network. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation and characterization of a novel solid titania precursor

Titania (TiO₂) is an important metal-oxide semiconductor and has a broad range of industrial applications in areas including pigment, photocatalysts, solar cells, ceramics, inorganic membranes, sensors, nonlinear optics and environmental purification, etc. Titania is often prepared using titania precursors. Here we report preparation of a novel solid titania precursor using a simple synthetic method, with a general chemical formula of TiSO₄(AcAc)_2−n(OH)_n · mH₂O (n < 2 and m < 2), that possesses high stability against hydrolysis and can be very conveniently employed for preparation of fine titania particles with no need of any solvent. Well dispersed TiO₂ nanoparticles with an average size of about 20 nm are prepared by directly annealing the solid titania precursor at 600 °C for 2 h. Characterization of the new solid titania precursor is carried out using transmission electron microscopy (TEM), thermogravimetry (TGA), Fourier transform infrared spectrometer (FT-IR) and X-ray diffractometer (XRD).     

Synthesis,crystal and molecular structure,and infrared characterization of two amino derivatives of 1,3,4-thiadiazole

2-amino-5-methyl-1,3,4-thiadiazole, 2-arnino-5-methyl-3H-1,3,4-thiadiazolium bromide[(amtzH)(amtz)Br] and bis (2,5-diamino-3H-1,3,4-thiadiazolium) sulphate [(a ₂ tzH)₂SO₄] were prepared and characterized by means of X-ray structural analysis and infrared spectroscopy. The crystals of (amtzH) (amtz)Br are monoclinic; space groupP2₁/c, witha=7.620(2),b=17.166(2),c=9.411(2)Å,=96.34(2)°, andZ=4. Its asymmetric unit contains one protonatedamtzH cation, one neutralamtz molecule, and one bromide ion. The crystals of (a ₂ tzH)₂SO₄ are monoclinic; space groupC2/c, witha=11.797(2),b=9.213(2),c=10.720(2)Å,=91.30(2)°, andZ=4. The structure is built up of one crystallographically independenta ₂ tzH cation and one half sulphate ion with crystallographically dictated twofold symmetry.     

Synthesis via sol–gel process and characterization of novel organic–inorganic coatings

Organic–inorganic coatings were synthesized from tetraethoxysilane (TEOS) and vinyltriacetoxysilane (VTAS) via dual process involving sol–gel reaction and radical polymerization. The deposition of the films was carried out using the spin-coating technique with the sample holder spinning at 1500 rpm. In order to determine the nature of products formed during the sol–gel reaction (i.e. polymerization) and to study the kinetics of this reaction, Fourier transform infrared (FTIR) spectroscopy experiments were performed. This technique allows also determining the optimal temperature of the final heat treatment. Thermogravimetric analysis (TGA) was used to study the influence of the ratio of organic and inorganic components on the thermal stability of the organic–inorganic hybrid, while differential scanning calorimetry (DSC) was used to determine its glass transition temperature. The chemical structure of this prepared hybrid material is also studied using FTIR with attenuated total reflection (ATR) device.Finally, the homogeneity of the chemical composition of the synthesized materials was checked by using the elemental distributions obtained by an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM). Moreover, nanoindentation measurements on thin films show enhanced hardness and elastic modulus with increasing silicate network.     

Synthesis,characterization and crystal structure of a novel 2D Cu(I) complex with flexible ligand

An exploration of the Cu(I)‐L system under hydrothermal conditions, has led to the isolation of a novel framework [Cu(I)(L)]_n ( 1 ) (L = bis(3,3‐dimethyl‐4,4‐dihydro‐1H‐pyrazol‐4‐yl)methane). Single‐crystal X‐ray analysis reveals that it crystallizes in the monoclinic, space group C2/c, a = 19.781(4) Å, b =11.026(3) Å, c = 16.339(4) Å, β = 127.186(3)°. The Cu ions are linked into an extended rainbow‐like chain via L molecules. Further, these adjacent chains are united together through hydrogen‐bonded interaction to a 2D layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,growth and characterization of l‐alaninium oxalate ‐ a novel organic NLO crystal

Nonlinear optical material of L‐alaninium oxalate (LAO) has been synthesized and single crystals are grown by slow evaporation technique. The solubility data of LAO is determined in water. Single crystal X‐ray diffraction study showed that LAO belongs to orthorhombic system with a non‐centrosymmetric space‐group P2₁2₁2₁. The functional groups have been identified from FT‐IR spectrum. The UV‐Vis‐NIR spectrum of LAO shows less optical absorption in the entire visible region. The second harmonic generation (SHG) in the material was estimated using Nd:YAG laser. The mechanical properties of the grown crystals are studied using Vickers microhardness tester. The AC and DC conductivity, and dielectric studies are also carried out and reported for the first time. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and characterization of a 5,6-dibromobenzoquinone-phenyl maleimide adduct

A six-step synthesis was used to prepare a 5,6-dibromobenzoquinone-phenyl maleimide adduct (8). The structure of (8) and four of the intermediates are described. This dibromide is used as the starting material for the synthesis of 2-amino-1,2,3-triazoles which reacts with aldehydes and ketones to prepare materials for nonlinear optical studies. The crystal structures of five compounds were determined. (2) Pbca, a = 8.4183(7), b = 7.2479(7), c = 31.272(3) Å; (3) P-1, a = 8.2023(8), b = 8.8130(8), c = 9.3555(9) Å, = 61.517(1), = 73.630(1), = 86.788(2)°; (4) P2₁/c, a = 11.181(1), b = 7.9157(7), c = 15.248(1) Å, = 90.691(2)°; (7) Pbca, a = 10.300(1), b = 20.184(3), c = 23.469(3) Å; (8) P2₁/n, a = 6.8975(6), b = 17.877(2), c = 14.089(1) Å, = 91.968(2)°.     

Synthesis and characterization of ferrierite

Ferrierite, a medium-port molecular sieve zeolite, was synthesized as the only crystalline phase from an aqueous gel of composition 1.6 Na₂O · 1.6 K₂O · Al₂O₃ · 13.5 SiO₂ · 130 H₂O · 0.8 CO₂ · 2.4 (HCO₂)₂ at 250 °C in reaction periods ranging from 40 to 95 hours. The crystallization time was reduced with seeding. Ferrierite was a metastable phase in this system and it transformed into tridymite, high sanidine and orthoclase at longer reaction periods. At 200 °C, chabazite was crystallized from the same batch composition at a very slow rate. At temperatures higher than 250 °C and in the absence of carbonates and bicarbonates in the batch mixture, tridymite, high sanidine and orthoclase crystallized directly without the formation of ferrierite. The synthetic ferrierite sorbs benzene, toluene and cyclohexane and behaves as a medium port molecular sieve. The sorption capacity of ferrierite was improved by acid treatments with no deterioration of the crystal structure.     

Synthesis and structural characterization of a novel polymeric gadolinium(III)–copper(II) complex of iminodiacetic acid

A novel polymeric Gd₂Cu₃ complex of iminodiacetic acid (H₂L¹=NH{CH₂COOH}₂), namely, Gd₂Cu₃(L¹)₆, 1, has been synthesized and structurally characterized. In the title complex, the Gd³⁺ ion is nine-coordinated by six O atoms from three bidentate chelating carboxylate groups and three O atoms from three anti-anti bridging carboxylic groups of six L¹ ligands; the Cu²⁺ ion is six-coordinated by four O and two N atoms from two chelating L¹ ligands. Each pair of Gd(III) atoms is bridged by three L¹ ligands, each of which also chelates with one copper(II) ion, thus forming a Gd₂Cu₃ cluster unit. Such cluster units are cross-linked by flexible L¹ ligands into a three-dimensional coordination framework. The title complex crystallizes in the trigonal space group P-3c1 (No. 165) with a = b = 13.433(4), c = 14.770(6) Å; V = 2308(1) ų; D_calca = 1.859 g cm^–3; Z = 2.     

Synthesis and characterization of a multicomponent Fe-based bulk amorphous alloy

A new bulk metallic glass (BMG) Fe₆₀B₁₅Zr₁₀Co₇Mo_5.5Y₂Si_0.5 was synthesized by Cu mold casting. The alloy was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) techniques. The thermal stability and glass-forming ability (GFA) of the alloy have been discussed by evaluating a number of thermal parameters. The maximum values of the key thermal parameters like T_rg (T_g/T_m, T_g/T_l), γ, δ and β parameters were found to be ～(0.66, 0.64), 0.407, 1.84 and 3.83, respectively. The alloy showed double stage crystallization process. The activation energies for crystallization were found to be 606.6 and 623.1 kJ/mol by Kissinger and Ozawa equations, which indicate the high thermal stability. Crystallization behavior of the alloy was explored by XRD. Mechanical properties like Vicker’s hardness, nanohardness and elastic modulus are found to be very promising.     

Synthesis,characterization of new carboxylic acid derivatives bearing 1,3,4-thiadiazole moiety and study their liquid crystalline behaviors

Thirteen carboxylic acid derivatives containing 1,3,4-thiadiazole ring in their core and swinging alkoxy terminal were synthesized. They were characterized by ¹H, ¹³C NMR spectroscopy, FTIR, and mass spectrometry. Their liquid crystalline behaviors have been studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The 1,3,4-thiadiazole compounds in this study were 2,5 di-substituted asymmetrical, alkoxy, and carboxy linkages. The compounds with alkoxy of long carbon chains (n > 7) displayed Smectic C phase. The liquid crystal properties were found to be affected by the length of alkoxy chain attached to the phenyl moiety and the two types of the dimeric form were resulted from the hydrogen bonding interaction between carboxylic acid molecules.     

Synthesis and molecular structure of a novel ring-fused borane derivative [(PhC)8C2H5]B

Reaction of 1,4-dilithiotetraphenylbutadiene with boron bromide affords the novel organoborane derivative [(PhC)₈C₂H₅]B (1) as yellow crystals characterized by ¹H, ¹³C NMR, elemental analyses, and single crystal X-ray diffraction. The title compound (1) crystallizes in the monoclinic space group P2 ₁/n, with cell parameters a = 15.519(10) Å, b = 12.240(6) Å, c = 25.497(16) Å, β = 95.369(10)°. Refinement converged at R = 0.0718. The average B–C bond distance in the title compound is 1.560 Å. An unusual structural feature of the title compound is the presence of an ethyl group that was probably abstracted from the diethyl ether solvent.     

Synthesis and characterization of nanocrystalline niobates

Nanocrystalline potassium niobates (KNbO₃, KNb₃O₈ and K₄Nb₆O₁₇) of different morphologies were synthesized with the low-temperature hydrothermal method by adjusting the alkalinity of the reaction system. A possible formation mechanism of the nanocrystalline niobates was proposed based on the experimental results. All of the products were characterized with X-ray powder diffraction and transition electron microscopy. The Fourier transform (FT) infrared, FT-Raman and UV–VIS properties of the niobates were studied.     

Synthesis and characterization of magnetite nanocrystals

Nanocrystals of magnetite (Fe₃O₄) were prepared by sol‐gel technique. The prepared nanocrystals were characterized for phase by powder X‐ray diffraction (XRD) of the samples annealed at successively higher temperature. The magnetite phase was formed during the annealing of the synthesized powder at 400 °C for a few hours. The Fourier transform infrared spectroscopy (FTIR) was performed to analyze the functional groups in the material. The energy dispersive X‐ray diffraction (EDAX) was performed for chemical composition analysis. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques were used to analyze the morphology of nanocrystals and for estimating their average size. The results confirm the formation of Fe₃O₄nanocrystals of the sizes ∼20–50 nm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)