Biophys. Chem. in press, 2018

 

G. Sánchez-Sanz, D. Crowe, A. Nicholson, A. Fleming, E. Carey, F. Kelleher

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

J. Phys. Chem. A,122, 1369, 2018

DOI:10.1021/acs.jpca.7b10920

G. Sánchez-Sanz, C. Trujillo

Improvement of Anion Transport Systems by Modulation of Chalcogen Interactions: The influence of solvent

A series of potential anion transporters, dithieno[3,2-b;2′,3′-d]thiophenes (DTT), involving anion-chalcogen interactions have been studied analysing the interaction energy, geometry and charge transfer. It was found that gas phase calculations show very negative interaction energies with short anion-chalcogen distances, but when solvent effects are considered the interaction energy values decreased drastically concomitantly with an elongation on the interatomic distances. In order to enhance the chalcogen interaction between the DTT derivatives and the anion, increasing the anion transporter capacity, bisisothioazole moiety was considered, i. e. the s-hole of the chalcogen atom was modulated by substitution of the adjacent carbon by a nitrogen atom in the S-C axis, increasing the depth of the s-hole and therefore the interaction between the chalcogen and anion. Finally, different anions were analysed within the complexes finding that F and NO3would be the best candidate to form complexes and possibly displace other anions such as Clor Br.

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