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71.
Jesús Castro Paulo Prez Lourido Antonio Sousa‐Pedrares Elena Labisbal Jos Piso Jos Arturo García‐Vzquez 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):m319-m322
The crystal structure of the title compound, [CoCl2(C6H12N2S)2], consists of monomer units of a CoII atom coordinated to two 1‐propylimidazolidine‐2‐thione ligands and to two chloride ions. The heterocyclic thione ligand is monodentate and coordinated to the metal through the thione S atom. The environment around the CoII atom is a slightly distorted tetrahedron. The Co—S bond lengths are 2.341 (2) and 2.330 (2) Å, and the Co—Cl bond lengths are 2.234 (2) and 2.238 (2) Å. The most important point of distortion is the S—Co—S bond angle of only 97.83 (8)°. Intramolecular classical hydrogen bonds are found between the chloride ions and the N—H groups. Additionally, intra‐ and intermolecular non‐classical hydrogen bonds are found. 相似文献
72.
Antonio Alberola 《Journal of organometallic chemistry》2007,692(13):2750-2760
Dithiazolyl radicals with π-stacking motifs have attracted particular interest because of their ability to exhibit spin-switching between diamagnetic distorted π-stacks and paramagnetic regular π-stacked structures through a solid state phase transition. Previous studies indicate that inclusion of electronegative heteroatoms into the backbone favours lamellar structures. This methodology has been extended to the synthesis and characterisation of the title compound, 4′-cyanobenzo-1,3,2-dithiazolyl (4-NCBDTA). Its electronic structure is probed through DFT calculations, cyclic voltammetry and EPR spectroscopy and its crystal structure determined by X-ray powder diffraction at room temperature. Variable temperature SQUID magnetometry reveals that 4-NCBDTA undergoes two phase transitions, each exhibiting bistability; a high temperature phase transition occurs at room temperature (TC↓ = 291 K, TC↑ = 304 K, ΔT = 13 K); whilst the low temperature phase transition occurs below liquid nitrogen temperatures (TC↓ = 37 K, TC↑ = 28 K;ΔT = 9 K). 相似文献
73.
[reaction: see text]. A very simple methodology to stereoselectively achieve tricyclic isonucleosides (nucleobase = thymine, uracil, and 5-fluoruracil) and 3'-C-branched nucleosides (nucleobase = theophylline) was performed by means of a DBU-mediated addition process using a readily available 2-bromo sugar. The mechanism for these transformations implies the loss of both substituents at C-2 and C-3 on the sugar moiety, and although it seems that DBU is probably involved, its involvement has not yet been ascertained. Cytosine did not react under these conditions. 相似文献
74.
Antonio Da Settimo Giampaolo Primofiore Bertacchi Maria Cristina Federico Da Settimo Anna Maria Marini 《Journal of heterocyclic chemistry》1995,32(3):941-945
The Ullmann reaction of 8-aminotheophylline or 8-aminocaffeine with 2-chlorobenzoic acid and of 8-bromotheophylline with ethyl-2-aminobenzoate afforded derivatives of three new heterocyclic systems: purino[7,8-α]quinazoline-5,9,11(6H,8H,10H)-trione, purino[8,9-b]quinazoline-2,4,11(1H,3H,5H)-trione and purino[8,7-b]quinazoline-2,4,6(1H,3H,11H)-trione, respectively. 相似文献
75.
Alvarez S Aullón G Fandos R García Fierro JL Ocón P Otero A Rojas S Terreros P 《Dalton transactions (Cambridge, England : 2003)》2005,(5):938-944
The reaction of [Rh(micro-Cl)(COD)]2 with 4,6-dimethyl-pyrimidinethiolate (Me2-pymt) and subsequent substitution of COD by CO yields [Rh(Me2-pymt)(CO)2]. The stacking pattern found in this compound is in contradiction with previously studied comparable square-planar complexes of type d8-[M(chelate)(monodentate)2] in which each ligand has different pi-acidic character. A theoretical study of the intermolecular interactions and conformation of the title compound has been carried out, combining semi-empirical band calculations on the real chains and ab initio(MP2 level) calculations on a model dimer. The combination of electronic and steric effects determines the rotation of the successive monomers and the deviation from linearity of the one-dimensional stacks. Its behaviour in solution is also special, developing a blue colour and forming micelles, when adding water to acetone solutions. 相似文献
76.
Domenico Armenise Nicolino De Laurentis Antonia Reho Antonio Rosato Flaviano Morlacchi 《Journal of heterocyclic chemistry》2004,41(5):771-775
A series of 6‐fluoro‐4‐(5 or 7)‐chloro‐2‐(difluorobenzoyl)aminobenzothiazoles 3a‐r were prepared to investigate their potential biological activity. In this work, the results of their in vitro antifungal activity against some strains of Candida albicans are reported. It was found that some derivatives displayed antifungal activity higher than that for 3k [1a] compound already described in literature. 相似文献
77.
Victoria Bejar Concepcion Calvo Juan Moliz Francisco Diaz-Martinez Emilia Quesada 《Applied biochemistry and biotechnology》1996,59(1):77-86
The exopolysaccharide produced byVolcaniella eurihalina, an halophilic eubacterium, under different environmental and nutritional conditions, is studied.V. eurihalina synthesizes an acidic heteropolysaccharide, composed by rhamnose, glucose, and mannose, as well as amino sugars, uronic acids,
and acetyl and sulphate residues. This composition varies depending on the nutrients of culture medium. Viscosity and pseudoplasticity
of the polymer solutions are also influenced by the nutritional conditions in which the microorganism was grown. 相似文献
78.
Andrea Cornia Antonio Costantino Fabretti Roberta Sessoli Lorenzo Sorace Dante Gatteschi Anne‐Laure Barra Carole Daiguebonne Thierry Roisnel 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m371-m373
The structure of hexadeca‐μ‐acetato‐tetraaquadodeca‐μ3‐oxo‐dodecamanganese bis(acetic acid) tetrahydrate, [Mn12O12(CH3COO)16(H2O)4]·2CH3COOH·4H2O, known as Mn12–acetate, has been determined at 83 (2) K by X‐ray diffraction methods. The fourfold (S4) molecular symmetry is disrupted by a strong hydrogen‐bonding interaction with the disordered acetic acid molecule of solvation, which displaces one of the acetate ligands in the cluster. Up to six Mn12 isomers are potentially present in the crystal lattice, which differ in the number and arrangement of hydrogen‐bonded acetic acid molecules. These results considerably improve the structural information available on this molecular nanomagnet, which was first synthesized and characterized by Lis [Acta Cryst. (1980), B 36 , 2042–2046]. 相似文献
79.
Atomic force microscopy imaging of hair: correlations between surface potential and wetting at the nanometer scale 总被引:2,自引:0,他引:2
Dupres V Camesano T Langevin D Checco A Guenoun P 《Journal of colloid and interface science》2004,269(2):329-335
We report investigations of hair surface potential under wetting at the nanometric scale by atomic force microscopy (AFM). Surface potential imaging was used to characterize the electrostatic properties of the hair samples. We found that the surface potential noticeably increases along the edges of the cuticles. These results are correlated with wetting behavior of different liquids performed using AFM in noncontact mode. 相似文献
80.
Antonio Currao Nantko Feiken Alceo Macchioni Reinhard Nesper Paul S. Pregosin Gerald Trabesinger 《Helvetica chimica acta》1996,79(6):1587-1591
The ligand (6,6′-dimethoxybiphenyl-2,2′-diyl)bis[3,5-di(tert-butyl)phenylphosphine] ( 1 ) forms an unexpectedly stable hydrido-bis-solvento complex of composition [RuH(isopropanol)2( 1 )]BF4, ( 2 ) under the conditions used in the enantioselective hydrogenation of pyrones. The structure of 2 , determined by X-ray diffraction, represents the first well-characterized chiral five-coordinate bis-phosphine ruthenium-hydride complex stable as a solvento complex, and provides a structural link in the enantioselective pyrone hydrogenation cycle catalyzed by [Ru(OAc)2( 1 )]. Using the arene complex [RuH(p-cymene)( 1 )]BF4 ( 3 ), the chiral pocket of coordinated 1 is shown to be relatively rigid, via NMR spectroscopy. This is reflected in restricted rotation about one of the four P–[3,5-di(tert-butyl)phenyl] P? Cipso bonds at room temperature. 相似文献