Encontrados 6 documentos, a visualizar página 1 de 1
The structure of betaxolol from single crystal X-ray diffraction and natural bo...
Canotilho, João; Castro, Ricardo A. E.; Rosado, Mário T. S.; Silva, M. Ramos; Beja, A. Matos; Paixão, J. A.; Redinha, J. SimõesThe structure of betaxolol obtained from ethanol:water solution was studied by X-ray diffraction. The geometrical parameters needed to define the structure are tabulated. The X-ray data show the existence of two conformers in the unit cell differing only in the conformation of the cyclopropylmethoxy fragment. Differences in the bond lengths angles and dihedral between both conformations are observed. The cyclop...
Conformational Isomorphism of Organic Crystals: Racemic and Homochiral Atenolol
Castro, R. A. Esteves de; Canotilho, João; Barbosa, Rui M.; Silva, M. Ramos; Beja, A. Matos; Paixão, J. A.; Redinha, J. SimõesX-ray diffraction analysis of (R,S)- and S-atenolol crystalline forms was performed. The crystals studied were grown from evaporation of an ethanol/water solution. (R,S)-Atenolol crystallizes in the centrosymmetric space group C2/c, and S-atenolol crystallizes in a noncentrosymmetric space group C2. There is one symmetry independent molecule in (R,S)-atenolol crystals and two symmetry independent molecules in S...
One-step synthesis of dipyrromethanes in water
Sobral, Abílio J. F. N.; Rebanda, Nuno G. C. L; Silva, Melo da; Lampreia, Sandra H.; Silva, M. Ramos; Beja, A. Matos; Paixão, J. A.In this communication we describe the first results of an efficient synthesis of [beta]-free-dipyrromethanes in water. This new method affords very pure products in moderate to high yields, using a cheap, non-toxic, environment friendly solvent, in a one-step procedure from pyrrole and carbonyl compounds, needing little or no work up procedures. ; http://www.sciencedirect.com/science/article/B6THS-48FBYP9-W/...
Pyrrolidine-based amino alcohols: novel ligands for the enantioselective alkyla...
Gonsalves, António M. d'. A. Rocha; Serra, M. Elisa S.; Murtinho, Dina; Silva, Vitor F.; Beja, A. Matos; Paixão, J. A.; Silva, M. RamosA series of easily obtained pyrrolidine-based [beta]-amino alcohols derived from tartaric acid and primary amines was synthesized and used as chiral ligands in the enantioselective alkylation of benzaldehyde. Using diethylzinc, 1-phenyl-1-propanol was obtained with enantiomeric excesses of up to 80% when (3S,4S)-N-(1-naphthylmethyl)-3,4-dihydroxypyrrolidine was used. The nature of the N-substituent on the ligan...
Crystal structure of tetrakis (µ-betaine-O,O') dichloro-dicopper(II) dichloride...
Silva, M. Ramos; Paixão, J. A.; Beja, A. Matos; Veiga, L. Alte da; Martín-Gil, J.[Cu2(bet)4Cl2]Cl2·4H2O (bet = betaine: IUPAC name: trimethylammonioacetate) is monoclinic, space group P21/c, a = 11.0510(10) Å, b = 14.7140(4) Å, c = 11.1620(15) Å, ß = 107.40(2)°. The dinuclear copper(II) cation [Cu2(bet)4Cl2]2+ is counterbalanced by two naked Cl- ions. The copper(II) ions have a square bipyramidal environment with oxygen atoms from the acetato groups in the basal planes and a chlorine and a ...
Crystal structure of the nonlinear optical compound L-arginine fluoride
Silva, M. Ramos; Paixão, J. A.; Beja, A. Matos; Veiga, L. Alte daL-arginine fluoride is a promising compound that exhibits nonlinear optical properties. It efficiently converts two single photons of the same polarization and frequency ? to one photon of frequency 2? (type I phase matching). C6H15N4O2+F- is monoclinic, space group P21, a = 5.4475(4) Å, b = 8.5133(6) Å, c = 10.2195(7) Å, ß = 93.475(6)°. The cation has a zwitterionic form, protonated at both the guanidyl and am...
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||