RESUMO
A new polymorphic form of ciprofloxacin saccharinate (CIP-SAC II) is presented, and compared with CIP-SAC I, a different polymorph which we had previously reported. The characterization techniques used were single crystal and powder X-ray diffraction, differential scanning calorimetry, thermogravimetry analysis and infrared and (13)C solid-state nuclear magnetic resonance spectroscopy. The results obtained from these techniques are consistent. Differential scanning calorimetry and thermogravimetric analysis showed that the reaction between the precursors is completed and the crystalline forms of both salts obtained (I and II) are highly pure. Infrared spectroscopy gave clear evidence of a salt formation. Solid-state nuclear magnetic resonance spectroscopy would indicate some degree of qualitative similarity in the intermolecular interaction scheme in both polymorphs, while thermal analysis data might indicate a difference in quantitative terms. A thorough single crystal structure determination of the new form CIP-SAC II allowed disclosing the most important inter- and intramolecular interactions.
Assuntos
Ciprofloxacina/química , Cristalização/métodos , Sacarina/química , Ciprofloxacina/síntese química , Cristalografia/métodos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Termogravimetria/métodosRESUMO
The structure of the title compound, [Mn(tpy)2](S4O6)*3H2O (tpy is 2,2':6',2"-terpyridine, C15H11N3), consists of monomeric [Mn(tpy)2]2+ units embedded in a complex anionic network made up of tetrathionate ions and hydration water molecules connected via a complex hydrogen-bonding scheme.
RESUMO
A regio- and stereospecific synthesis of monoarylimino o-quinones derived from beta-lapachone (1) was achieved by treatment of the quinone with a slight excess of an arylamine in the presence of an excess of triethylamine/titanium tetrachloride 4:1. Imine formation occurred exclusively at position 6, giving the Z diastereomer, as determined by single-crystal X-ray analysis. In vitro tests for cytotoxicity in 55 human cancer cell cultures showed a substantial loss in activity for the p-nitrophenylimine (5), whereas the phenylimine (2), p-methylphenylimine (3), and p-methoxyphenylimine (4) retained (or bettered) most of the cytotoxicity and selectivity of the parent quinone. Preliminary in vivo testing in hollow fiber assays against a standard panel of 12 human tumor cell lines showed that although beta-lapachone failed, compounds 2 and 3 had good scores with net cell kills.
Assuntos
Antineoplásicos/síntese química , Iminas/síntese química , Naftalenos/síntese química , Naftoquinonas/química , Piranos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Iminas/química , Iminas/farmacologia , Espectroscopia de Ressonância Magnética , Naftalenos/química , Naftalenos/farmacologia , Piranos/química , Piranos/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Células Tumorais CultivadasRESUMO
Extended Hückel and density functional calculations carried out on 128-MVE Cu(8)(dithiolato)(6) edge-bridged cubic clusters indicate that their stability is mainly driven by the chelating effect of the ligands, which provide a stable 16-electron configuration to the approximately trigonal planar metal centers. Nevertheless, a weak but significant d(10)-d(10) bonding interaction is present which is rather independent from the dithiolato bite effect. The metal centers have a nonbonding 4p(z)() vacant AO pointing to the center of the cube available for bonding to an encapsulated atom. The electronic closed-shell requirement is satisfied for the 136-MVE and 140-MVE counts, respectively, when a main-group atom or a transition-metal atom is incorporated in the middle of the cube. The bonding within these dithiolato compounds is compared to other edge-bridged M(8) cubic clusters. In particular, it is shown that clusters of higher nuclearity but containing an M(8) cubic core are related to the dithiolato species. Indeed, their outer metal atoms can be considered as belonging to the ligand shell, interacting with the M(8) cube in a way similar to the dithiolato ligands in the Cu(8) species.