Apparent shortening of the Csp(3)-Csp(3) bond analysed via a variable-temperature X-ray diffraction study in racemic 1,1 '-binaphthalene-2,2 '-diyl diethyl bis(carbonate)

Crystal structure determination at room temperature [292 (2) K] of racemic 1,1'-binaphthalene-2,2'-diyl diethyl bis(carbonate), C26H22O6, showed that one of the terminal carbon-carbon bond lengths is very short [Csp(3)-Csp(3) = 1.327 (6) angstrom]. The reason for such a short bond length has been analysed by collecting data sets on the same crystal at 393, 150 and 90 K. The values of the corrected bond lengths clearly suggest that the shortening is mainly due to positional disorder at two sites, with minor perturbations arising as a result of thermal vibrations. The positional disorder has been resolved in the analysis of the 90 K data following the changes in the unit-cell parameters for the data sets at 150 and 90 K, which appear to be an artifact of a near centre of symmetry relationship between the two independent molecules in the space group P (1) over bar at these temperatures. Indeed, the unit cell at low temperature (150 and 90 K) is a supercell of the room-temperature unit cell.

Unusual Anisotropic Effects from 1,3-Dipolar Cycloadducts of 4-Azidomethyl Coumarins

4-Bromomethylcoumarins (1) reacted with sodium azide in aqueous acetone to give 4-azidomethyl-coumarins (2), which underwent 1,3-dipolar cycloaddition with acetylenic dipolarophiles to give triazoles (3). These triazoles (3) have been found to exhibit interesting variations in the chemical shifts of C-3-H and C-4-methylene protons. Protonation studies indicate that the shielding effect of the C-3-H of coumarin is due to pi-electrons of the triazole ring, further supported by diffraction and computational studies.

Ethyl 6-chloro-2-methyl-4-phenylquinoline-3-carboxylate

In the title compound, C19H16ClNO2, the quinoline ring system is planar (r.m.s. deviation = 0.008 angstrom). The phenyl group and the -CO2 fragment of the ester unit form dihedral angles of 60.0 (1) and 60.5 (1)degrees, respectively, with the quinoline ring system.

Comparison of performance parameters of poly(3,4 ethylenedioxythiophene) (PEDOT) based electrochromic device on glass with and without counter electrode

Conjugated polymers are promising materials for electrochromic device technology. Aqueous dispersions of poly(3,4-ethylenedioxythiophene)-(PEDOT) were spin coated onto transparent conducting oxide (TCO) coated glass substrates. A seven-layer electrochromic device was fabricated with the following configuration: glass/transparent conducting oxide (TCO)/PEDOT (main electrochromic layer)/gel electrolyte/prussian blue (counter electrode)/TCO/glass. The device fabricated with counter electrode (Prussian blue) showed a contrast of 18% and without counter electrode showed visible contrast of 5% at 632 nm at a voltage of 1.9 V. The comparison of the device is done in terms of the colouration efficiency of the devices with and without counter electrode.

Disorder Induced Concomitant Polymorphism in 3-Fluoro-N-(3-fluorophenyl)benzamide

The occurrence of concomitant polymorphism in 3-fluoro-N-(3-fluorophenyl) benzamide has been identified to be due to the disorder in the crystal structure. Of the two modifications, the plate form (Form I) crystallizes in the monoclinic centrosymmetric space group C2/c with Z = 4, and the needle form (Form II) crystallizes in the noncentrosymmetric space group P21 with Z = 2. An interesting positional disorder at the bridging atoms in both forms holds the molecular conformation identical, while subtle variations brought by N−H···O hydrogen bonds along with weak C−H···F and F···F interactions result in packing polymorphism.

Crystal structure of 3-acetylcoumarin-o-aminobenzoylhydrazone and synthesis, spectral and thermal studies of its transition metal complexes

Transition metal [Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)] complexes of a new Schiff base, 3-acetylcoumarin-o-aminobenzoylhydrazone were synthesized and characterized by elemental analyses, magnetic moments, conductivity measurements, spectral [Electronic, IR, H-1 and C-13 NMR, EPR] and thermal studies. The ligand crystallizes in the monoclinic system, space group P2(1)/n with a = 9.201(5), b = 16.596( 9), c = 11.517(6) angstrom, beta= 101.388(9)degrees, V = 1724.2 (17) angstrom(3) and Z = 4. Conductivity measurements indicated Mn(II) and Co(II) complexes to be 1 : 1 electrolytes whereas Ni(II), Cu(II), Zn(II) and Cd(II) complexes are non-electrolytes. Electronic spectra reveal that all the complexes possess four-coordinate geometry around the metal.

Coordination polymers and hybrid networks of different dimensionalities formed by metal sulfites

In our effort to explore the use of the sulfite ion to design hybrid and open-framework materials, we have been able to prepare, under hydrothermal conditions, zero-dimensional [Zn(C12H8N2)(SO3)]center dot 2H(2)O, I (a = 7.5737(5) angstrom, b = 10.3969(6) angstrom, c = 10.3986(6) angstrom, alpha = 64.172(1)degrees, beta = 69.395(1)degrees, gamma = 79.333(1)degrees, Z = 2, and space group P (1) over bar), one-dimensional [Zn-2(C12H8N2)(SO3)(2)(H2O)], II (a = 8.0247(3) angstrom, b = 9.4962(3) angstrom, c = 10.2740(2) A, alpha = 81.070(1)degrees, beta = 80.438(1)degrees, gamma = 75.66(5)degrees, Z = 2, and space group P (1) over bar), two-dimensional [Zn-2(C10H8N2)(SO3)(2)]center dot H2O, III (a = 16.6062(1) angstrom, b = 4.7935(1) angstrom, c = 19.2721(5) angstrom, beta = 100.674(2)degrees, Z = 4, and space group C2/c), and three-dimensional [Zn-4(C6H12N2)(SO3)(4)(H2O)(4)], IV (a = 11.0793(3) angstrom, c = 8.8246(3) angstrom, Z = 2, and space group P42nm), of which the last three are coordination polymers. A hybrid open-framework sulfite-sulfate of the composition [C2H10N2][Nd(SO3)(SO4)(H2O)](2), V (a = 9.0880(3) angstrom, b = 6.9429(2) angstrom, c = 13.0805(5) A, beta = 91.551(2)degrees, Z = 2, and space group P2(1)/c), with a layered structure containing metal-oxygen-metal bonds has also been described.

Enantiospecific synthesis of ABC-ring system of A-nor and abeo 4(3 -> 2) tetra and pentacyclic triterpenes

Enantiospecific synthesis of ABC-ring systems of A-nor and abeo 4(3 -> 2) tetra and pentacyclic triterpenes has been accomplished starting from the readily available monoterpene (R)-carvone. (R)-Carvone was used as the B-ring of the target molecules. A lithium-liquid ammonia mediated cyclisation of delta,epsilon-unsaturated ester was employed for the cyclopentannulation at the C-5 and C-6 carbons of carvone and an RCM reaction was employed for the cyclohexannulation to generate the ABC-ring system of A-nor tetra and pentacyclic triterpenes. The strategy has been extended for the synthesis of the ABC-ring system of abeo 4(3 -> 2) tetra and pentacyclic triterpenes. (C) 2009 Elsevier Ltd. All rights reserved.

Amine-Templated Aluminoborates Exhibiting Graphite and Diamond Nets

A solvothermal reaction of Al2O3, H3BO3, pyridine, and H2O at 180 degrees C/7 days in the presence of organic amine molecules gave rise to four new aluminoborates, [(C6H18N2)(AlB6O13H3)], I; [(C5H16N2) (AlB5O10)]center dot 2H(2)O, II; [(C5H16N2)-(AlB5O10)], III; and [(C5H17N3)(AlB5O10)] center dot H2O, IV, with two- and three-dimensional structures. All the structures have been formed by the connectivity involving Al3+ ions and [B5O10] cyclic pentaborate units. In 1, the 3-connected trigonal nodes form a layer that resembles a graphite structure has been observed. The compounds II, III, and IV, have 4-connected nodes that forms a diamond related three-dimensional structure. The formation of solvatomorphs in II and III is noteworthy and has been observed first time in a family of amine template aluminoborates. A comparison of the various aluminoborate structures reveals subtle relationships between the organic amines (length of the amines) and the final framework structures. The compounds have been characterized using a variety of techniques including IR, second-order optical behavior, and MAS NMR studies.

3-Benzyl-6-benzylamino-1-methyl-5-nitro-1,2,3,4-tetrahydropyrimidine

In the title compound, C19H22N4O2, the tetrahydropyrimidine ring adopts an envelope conformation (with the N atom connected to the benzyl group representing the flap). This benzyl group occupies a quasi-axial position. The two benzyl groups lie over the tetrahydropyridimidine ring. The amino group is a hydrogen-bond donor to the nitro group.

1-[5-Acetyl-4-(4-bromophenyl)-2,6-dimethyl-1,4-dihydropyridin-3-yl]eth anone monohydrate

The 1,4-dihydropyridine ring in the title hydrate, C17H18BrNO2 center dot H2O, has a flattened-boat conformation, and the benzene ring is occupies a position orthogonal to this [dihedral angle: 82.19 (16)degrees]. In the crystal packing, supramolecular arrays mediated by N-H center dot center dot center dot O-water and O-water-H center dot center dot center dot O-carbonyl hydrogen bonding are formed in the bc plane. A highly disordered solvent molecule is present within a molecular cavity defined by the organic and water molecules. Its contribution to the electron density was removed from the observed data in the final cycles of refinement and the formula, molecular weight and density are given without taking into account the contribution of the solvent molecule.

From the {Cu(μ2-S)N}4 butterfly architecture to the {Cu(μ3-S)N}12 double wheel

Copper(I) complexes with {Cu(μ2-S)N}4 and {Cu(μ3-S)N}12 core portions of butterfly-shaped or double wheel architectures have been isolated in the reaction of Cu(I) with the Schiff base ligand C6H4(CHNC6H4S)2, aiso-abtâ, under different conditions. View the MathML source containing the tetranuclear electroneutral complex View the MathML source is formed by the reaction of CuI in acetonitrilic solution and recrystallization from DMF, whereas View the MathML source containing dodecanuclear View the MathML source wheels is accessible starting from CuBF4. Complexes 2 and 4 represent the first examples of cyclic complexes with the same overall stoichiometry but different ring sizes. The ligand induces two different coordination environments around copper(I) by switching between μ2- and μ3-sulfur bridging modes.