Navegando por Autor "Doriguetto, Antônio Carlos"
Agora exibindo 1 - 3 de 3
- Resultados por Página
- Opções de Ordenação
Item A comparative study on the crystal structure of bicycle analogues to the natural phytotoxin helminthosporins(Journal of Molecular Structure, 2016-02-05) Barbosa, Luiz Cláudio de Almeida; Teixeira, Robson Ricardo; Nogueira, Leonardo Brandão; Maltha, Celia Regina Alvares; Doriguetto, Antônio Carlos; Martins, Felipe TerraHerein we described structural insights of a series of analogues to helminthosporin phytotoxins. The key reaction used to prepare the compounds corresponded to the [3 + 4] cycloaddition between the oxyallyl cation generated from 2,4-dibromopentan-3-one and different furans. Their structures were confirmed upon IR, NMR and X-ray diffraction analyses. While bicycles 7, 8 and 9 crystallize in the centrosymmetric monoclinic space group P21/c, compound 10 was solved in the noncentrosymmetric orthorhombic space group P212121. The solid materials obtained were shown to be racemic crystals (7, 8, 9) or racemic conglomerate (10). In all compounds, there is formation of a bicycle featured by fused tetrahydropyranone and 2,5-dihydrofuran rings. They adopt chair and envelope conformations, respectively. Crystal packing of all compounds is stabilized through C–H•••O contacts. Conformational aspects as well as similarities and differences among the crystal structures of the synthesized analogues are discussed.Item Conformerism, enantiomorphism and double catemer motifs in para-substituted nostoclide analogues(Journal of Molecular Structure, 2016-02-15) Teixeira, Róbson Ricardo; Barbosa, Luiz Claudio Almeida; Antolinez, Isabel Valero; Corrêa, Rodrigo de Souza; Martins, Felipe Terra; Doriguetto, Antônio CarlosWe have here elucidated the crystal structures of five nostoclide analogues. A common feature in all compounds is a substituent at the para-position of the benzylidene group. Compounds with either bromine (3) or hydroxyl (4) as para-substituent crystallizes with Z’ = 2 as result of conformerism. It was also observed that Z' > 1 in the compound with a para-dimethylamino substituent (1). However, its four crystallographically independent molecules are conformationally similar. They are not related by crystallographic symmetry due to the offset packing of their C–H … OC nonclassical hydrogen bonded double chains. This compound (1) has also crystallized in a chiral space group (P21) despite the lack of a stereocenter. Such enantiomorphism phenomenon is related to the presence of only one of the two mirror benzyl conformations with phenyl ring at the equatorial position opposite the lactone oxygen atom. The molecular mean plane of nostoclide analogues has been featured by high level of planarity, except in the brominated compound where two twisted conformations occurred due to rotations on the single bond axis into benzylidene group. The benzyl conformation has been the greatest difference between the two crystallographically independent molecules of the para-hydroxylated compound (4). The crystal packing of the compounds is marked by double catemer motif assembled through C–H … OC non-classical hydrogen bonds, although C–H … π interactions do play an important role in stabilizing the crystal packing of some compounds of the series.Item Synthesis, characterization, and structural determination of copper(II) complexes with alkyl derivatives of hydroxybenzophenones(Journal of Coordination Chemistry, 2017) Santos, Marcelo Henrique Dos; Gonçalves, Cristiane Batista; Marinho, Maria Vanda; Dias, Danielle Ferreira; Martins, Felipe Terra; Doriguetto, Antônio CarlosFour mononuclear copper(II) complexes, [Cu(LFQM-115)2] (1), [Cu(LFQM-116)2] (2), [Cu(LFQM-117)2] (3) and [Cu(octyloxy)2] (4) [LFQM-115 = 2-hydroxy-4-O-methylbenzophenone (C14H11O3), LFQM-116 = 2-hydroxy-4-O-butylbenzophenone (C17H18O3), LFQM-117 = 2-hydroxy-4-O-(33-dimethylallyl)benzophenone (C18H18O3) and octyloxy = 2-hydroxy-4-O-octylbenzophenone (C21H25O3)], have been prepared and investigated by infrared spectroscopy, thermal analysis, and powder and single crystal X-ray diffraction. Even though the synthesis and infrared analysis of 1, 2, and 4 have been reported previously, their crystal structures were elucidated for the first time here. In addition, the crystal structures of LFQM-116 and LFQM-117 were also determined by single crystal X-ray diffraction. The pseudo-translational symmetry found in LFQM-116 and the isomorphism between LFQM-115 and LFQM-117 are discussed. The complexes were prepared from a reaction of copper(II) nitrate trihydrate and the respective ligand in a (1:2) molar ratio in methanol (for 1 and 2) or THF (for 3 and 4) with addition of NaOH. Furthermore, crystallographic studies show that each copper(II) exhibits a square planar geometry, coordinated by four oxygens of two ligands. The nature and crystal packing of the intermolecular interactions are discussed. Compounds 2 and 3 are isomorphic crystals and all structures have the same supramolecular synthon.