2,859 publications from this institution
A novel procedure for the preparation of few-layers boron nitride (BN), either as films or as suspended BN platelets, is presented, based on the pyrolysis of chitosan, which serves both as a matrix to embed ammonium borate and as a template for BN synthesis. The resulting BN samples are characterized by XRD, Raman and X-ray photoelectron spectroscopy, and by TEM and AFM imaging. The samples exhibit deep UV emission, which is characteristic of high quality BN. This template synthesis and the easy exfoliation of BN platelets facilitate the use of BN as an extremely high-efficiency Fenton catalyst for the generation of highly aggressive hydroxyl radicals in water.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Benzotriazole-activated pyrazinoic acid was utilized as a versatile building block for the efficient and convenient synthesis of novel hybrid conjugates of pyrazinoic acid with secondary amines via amino acid linkers in high yields.
In the title compound, C(8)H(10)N(2)O(3)S, the dihedral angle between the acetamide group and the benzene ring is 15.59 (12)° and the amino group is close to being perpendicular to the benzene ring [N-S-C(ar)-C(ar) (ar = aromatic) torsion angle = 109.4 (2)°]. In the crystal, mol-ecules are linked into supra-molecular tubes parallel to [001] by amine-amide N-H⋯O inter-actions and these are connected into the three-dimensional architecture by amide-sulfonamide N-H⋯O hydrogen bonds. The crystal studied was a racemic twin.
In this critical review the reactivity patterns observed with different types of diyne substrates in gold catalysis are discussed. Apart from the many examples from homogeneous catalysis, the few examples from heterogeneous gold catalysis are also included. With a proper arrangement of the two alkynes unique and exciting reactivity patterns like 1,3-carbonyl transpositions, carbene transfer reactions, cascade annulations, macrocyclisations or the formation of gold vinylidene intermediates are observed. These reactions are of interest for organic synthesis, for pharmaceutical and medicinal chemistry and for material science.
Additional file 1. Cartesian co-ordinates of optimized geometries and cif files of 3a and 3b are given in supporting information. Experimental 1H,13C-NMR are also pasted in supporting information along with HOMOâ LUMO surfaces, simulated UVâ vis. Spectra and Tables containing bond length and bond angles data.
The 2-{4-[2-benzylidenehydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 1), 2-{4-[2-(1-naphthylmethylene)hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 2) and 2-{4-[2-(9-anthrylmethylene)- hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 3) were synthesized by direct tricyanovinylation of hydrazones. The bathochromic shift in absorption spectra has been observed by increasing the solvent polarity. The FTIR spectra of these new dyes exhibited three important absorption bands. The first band centered near 3260 cm-1 in System 1 while 3208 cm-1 and 3211 cm-1 in System 2 and System 3 for the nNH absorption, respectively. The second band is a sharp absorption band in the region of 2212-2209 cm-1, which was attributed to the cyano group absorption. The third is an absorption band in the region of 1611-1603 cm-1 ascribed for the C=N. Density functional theory (DFT) calculation of relative energies, relative enthalpies and free energies shows that E isomers are the most stable except System 3 in which the most stable is Z isomers. The conformational energy profile shows two maxima near (-90 and 90o) while three local minima observed at (-180, 0 and 180) for N1-N2-C1-C2 torsional angle. The highest occupied molecular orbitals (HOMOs) are localized on the whole molecules while lowest unoccupied molecular orbitals (LUMOs) are distributed on the tricarbonitrile. KEY WORDS: Dye-sensitized solar cells, HOMO, LUMO, Absorption, FTIR spectra Bull. Chem. Soc. Ethiop. 2015, 29(1), 137-148DOI: http://dx.doi.org/10.4314/bcse.v29i1.13
