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A study of the structure of the pindolol based on infrared spectroscopy and nat...
Castro, Ricardo A. E.; Canotilho, João; Nunes, Sandra C. C.; Eusébio, M. Ermelinda S.; Redinha, J. Simõeshttp://www.sciencedirect.com/science/article/B6VNG-4V1KMV6-1/2/37bbea9fe5940f0b4f9225e65592559b
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...
Infrared spectroscopy of racemic and enantiomeric forms of atenolol
Castro, R. A. Esteves de; Canotilho, João; Barbosa, Rui M.; Redinha, J. SimõesThe molecular structure of conformational isomorphs given by X-ray diffraction for racemic and enantiomeric atenolol were optimized at the HF/6-31G* level of theory and the infrared spectra of the structure were calculated. These spectra are used to characterize the differences between the various atenolol conformers. ; http://www.sciencedirect.com/science/article/B6VNG-4M3R2CM-5/1/b10f1bad0cbecc44994eccae4c...
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...
Infrared study of the acidic and basic forms of betaxolol
Canotilho, João; Castro, R. A. Esteves de; Helena, M.; Teixeira, S. F.; Leitão, M. Luísa P.; Redinha, J. SimõesBetaxolol and its respective hydrochloride salt were studied in solution by computational calculations and infrared spectroscopy. The solution molecular conformations were taken to be the same as those exhibited by the compounds in the solid state given by X-ray diffraction and calculated after full geometry optimization by ab initio Hartree-Fock methods using the 6-31G(d) basis set. Infrared spectra of carbon ...
Effect of solvent and temperature on solution-crystallized terfenadine
Leitão, M. Luísa P.; Canotilho, João; Ferreira, Simone C. R.; Sousa, Adriano T.; Redinha, J. SimõesThe aim of this work was to understand the crystallization process of terfenadine in solution. ; http://www.sciencedirect.com/science/article/B6THV-49SWCDJ-1/1/bfcb0feff088fbe244525634b1e2dfda
Enthalpy of vaporisation of butanediol isomers
Eusébio, M. Ermelinda; Jesus, A. J. Lopes; Cruz, Mafalda S. C.; Leitão, M. Luísa P.; Redinha, J. SimõesThe enthalpies of vaporisation of isomers of butanediol were determined by calorimetric measurements. A Knudsen effusion cell was used for this purpose. ; http://www.sciencedirect.com/science/article/B6WHM-47K2P6J-2/1/6a970623f372c267e60917eff9f702c6
Infrared spectroscopy and the characterization of terfenadine crystallized from...
Leitão, M.; Canotilho, J.; Sousa, A.; Pais, A.; Sousa, A.; Redinha, J. SimõesAbstract In this paper the structural characterization of terfenadine crystallized from ethanol-water, ethanol and methanol is performed by infrared spectroscopy. The OH stretching vibration, composed of three markedly overlapped bands, is analyzed by peak fitting. The assignment of the hydrogen bonds was conducted making use of band parameters, spectroscopic data for CCl4 solutions, and molecular dynamics cal...
Enthalpy of solution of terfenadine in ethanol/water mixtures
Canotilho, João; Costa, Felisbela S.; Sousa, Adriano T.; Redinha, J. Simões; Leitão, M. Luísa P.The enthalpy of solution of terfenadine in ethanol/water mixtures, 0-20.5 wt.% of water was determined by calorimetry. A Sudden increase of 1-2 kJ mol-1 in the enthalpy at a concentration value around 0.01 mol kg-1 is observed. This step in the enthalpy is interpreted as due to solute n-mer aggregates formation. The solubility of terfenadine in the cosolvent systems used in the calorimetric studies was determin...
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