RESUMEN
We explore herein the supramolecular interactions that control the crystalline packing in a series of fluorothiolate triphenylphosphine gold(I) compounds with the general formula [Au(SRF)(Ph3P)] in which Ph3P = triphenylphosphine and SRF = SC6F5, SC6HF4-4, SC6F4(CF3)-4, SC6H3F2-2,4, SC6H3F2-3,4, SC6H3F2-3,5, SC6H4(CF3)-2, SC6H4F-2, SC6H4F-3, SC6H4F-4, SCF3, and SCH2CF3. We use for this purpose (i) DFT electronic structure calculations and (ii) the quantum theory of atoms in molecules and the non-covalent interactions index methods of wave function analyses. Our combined experimental and computational approach yields a general understanding of the effects of ligand fluorination in the crystalline self-assembly of the examined systems, in particular, about the relative force of aurophilic contacts compared with other supramolecular interactions. We expect this information to be useful in the design of materials based on gold coordination compounds.
RESUMEN
INTRODUCTION: Corynebacterium coyleae is a Gram-stain-positive non-lipophilic coryneform rod first described in blood samples and pleural fluid. There is scarce information about the clinical relevance of C. coyleae and none on complicated urinary tract infections has been described so far. CASE PRESENTATION: A 36-year-old woman with a history of chronic kidney failure, under thrice-weekly haemodialysis since 2014 due to polycystic kidney disease, presented with hypogastric pain, lower left quadrant pain and nausea. Since 1997, the patient had developed several episodes of urinary tract infection. On admission, the patient presented tenderness in the lower abdomen and fist positive lumbar percussion. Urine culture showed significant bacterial growth (>105 c.f.u. ml-1). Slightly glistening colonies of 1 mm in diameter were observed after a 24 h incubation. Gram staining showed coryneform Gram-stain-positive rods. The patient was diagnosed as having a complicated urinary tract infection. A bilateral nephrectomy was performed on the fourth day of hospitalization. Two samples of kidney tissue were sent for culture. Direct examination of the material revealed the presence of abundant inflammatory reaction and Gram-positive diphtheroid rods. The organism was identified using MALDI-TOF and conventional biochemical tests; in both isolates further identification was performed by PCR amplification and sequence analysis of the rpoB gene as Corynebacterium coyleae. CONCLUSIONS: C. coyleae is an infrequent species among the genus Corynebacterium that should be considered as an emerging pathogen that can be involved in nosocomial infections and complicated urinary tract infections.
RESUMEN
State-of-the-art chemical bonding analyses show that water clusters have a bifunctional catalytic role in the formation of H2SO4 in acid rain. The embedded H2O monomers mitigate the change in the chemical bonding scenario of the rate-limiting step, reducing thereby the corresponding activation energy in accordance with Hammond's postulate. We expect that the insights given herein will prove useful in the elucidation of the catalytic mechanisms of water in inorganic and organic aqueous chemistry.
RESUMEN
We analyzed non-additive effects in resonance assisted hydrogen bonds (RAHBs) in different ß-enolones, which are archetypal compounds of these types of interactions. For this purpose, we used (i) potential energy curves to compute the formation energy, ΔE, of the RAHBs of interest in different circumstances along with (ii) tools offered by quantum chemical topology, namely, the Quantum Theory of Atoms In Molecules (QTAIM) and the Interacting Quantum Atoms (IQA) electronic energy partition. We established the effect that a given H-bond exerts over ΔE associated with another RAHB, determining in this way the cooperativity or the anticooperativity of these interactions. The mesomeric structures and the QTAIM delocalisation indices are consistent with the determined cooperative or anticooperative character of two given RAHBs. The HB cooperativity and anticooperativity studied herein are directly reflected in the IQA interaction energy E, but they are modulated by the surrounding hydrocarbon chain. The IQA decomposition of ΔEcoop, a measure of the cooperativity between a pair of interacting RAHBs, indicates that the analyzed H-bond cooperative/anticooperative effects are associated with greater/smaller (i) strengthening of the pseudo-bicyclic structure of the compounds of interest and (ii) electron localisations with its corresponding changes in the intra and intermolecular exchange-correlation contributions to ΔE. Overall, we expect that this investigation will provide valuable insights into the interplay among hydrogen bonded atoms and the π system in RAHBs contributing in this way to the understanding of the general features of H-bonds.