Estudios teóricos ab initio de lantánidos pesados en sólidos: Yb2+ en haluros

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química. Fecha de lectura: 15-10-201

Conformational studies of Gram-negative bacterial quorum sensing acyl homoserine lactone (AHL) molecules: The importance of the n → π* interaction

A 1H NMR study shows the presence of intermolecular hydrogen bonds for AHLs in CDCl3 solution. A detailed computational study of the structure of AHLs and the relative stability between the extended conformations (X) and those showing n → π* interactions (np) have been carried out by means of DFT calculations. Solvent effects have been shown to be very important when stabilising np conformations, particularly with polar solvents. This was shown by the shortening of C⋯O intramolecular distances and the increase in the relative energies favouring the np conformation with the dielectric constant of the solvent. The charge transfer between the O donor and the acceptor carbonyl group, assessed by second order perturbation energies, E(2), also shows an increase in the E(2) values with the dielectric constant of the solvent

Conformational Studies of Gram-Negative Bacterial Quorum Sensing Acyl Homoserine Lactone (AHL) Molecules: the Importance of the n→* Interaction

A 1H NMR study shows the presence of intermolecular hydrogen bonds for AHLs in CDCl3 solution. A detailed computational study of the structure of AHLs and the relative stability between the extended conformations (X) and those showing n→p* interactions (np) have been carried out by means of DFT calculations. Solvent effects have been shown to be very important when stabilising np conformations, particularly with polar solvents. This was shown by the shortening of C···O intramolecular distances and the increase in the relative energies favouring the np conformation with the dielectric constant of the solvent. The charge transfer between the O donor and the acceptor carbonyl group, assessed by second order perturbation energies, E(2), also shows an increase in the E(2) values with the dielectric constant of the solvent

Linear free energy relationships in halogen bonds

Four models of halogen bonds were used to quantify this bond using the DFT B97D/6-311+G(d) computational level: para-substituted iodobenzenes, para- and meta-substituted bromobenzenes complexed with three simple Lewis bases (NH 3, NCH and CNH), 1-bromo-4-substituted-bicyclo[2.2.2]octanes with NH3 and 3- and 4-substituted pyridines complexed with BrCl and BrF. In addition, the combination of the para-substituted bromobenzenes with the 4-substituted pyridines has been studied. A total of 459 complexes have been optimized and are discussed in the present article. The energetic and geometric results have been analyzed based on the properties of the substituents and the isolated molecules involved in the interaction. The Hammett-Taft parameters provide reasonable correlations with the interaction energies. However, excellent correlations are obtained in all the cases when the electrostatic properties of the two molecules involved in the interaction are considered (R2 > 0.99).Peer Reviewe