Showing papers by "Rosa M. Claramunt published in 2020"
TL;DR: Weak hydrogen bonds are increasingly hypothesised to play key roles in a wide range of chemistry from catalysis to gelation to polymer structure, and here, 15N/13C spin-echo magic-angle spinning (MAS) solid-state NMR experiments are applied to "view" intermolecular CH···N hydrogen bonding in two selectively labelled organic compounds.
Abstract: Weak hydrogen bonds are increasingly hypothesized to play key roles in a wide range of chemistry from catalysis to gelation to polymer structure. Here, 15N/13C spin-echo magic-angle spinning (MAS) ...
19 citations
7 citations
TL;DR: The theoretical characterization of 13C and 15N CPMAS NMR of known bromo-derivative crystals by using both the GIPAW and the combined GIAO-ZORA-SO approximation methods is reported.
5 citations
24 Sep 2020
TL;DR: The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values, allowed the determination of several structural effects.
Abstract: Nine 3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones (17-25), some of which contain fluoro-substituents, have been regiospecifically prepared by reaction of 2,3-diaminopyridines with ethyl aroylacetates. In two cases, open intermediates have been isolated and these are related to the reaction pathway. The X-ray crystal structure of 1-methyl-4-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (23) has been solved (formula, C15H13N3O; crystal system, monoclinic; space group, C2/c). This is an asymmetric unit constituted by a single nonplanar molecule and its conformational enantiomer due to the presence of the seven-membered diazepin-2-one moiety, which introduces a certain degree of torsion in the adjacent pyridine ring. The 1H, 13C, 15N, and 19F NMR spectra were obtained and the chemical shifts, together with those of the previously published 1,3-dihydro-2H-benzo[b][1,4]diazepin-2-ones (1-16), i.e., a total of 544 values, were successfully compared with the chemical shifts calculated at the gauge invariant atomic orbital (GIAO)/Becke, three-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,p) level. The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (25) was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values. This allowed the determination of several structural effects. The rotation about the exocyclic N1-CR bond was also calculated and its dynamic properties were discussed.
4 citations
TL;DR: In 2018, PGC2018•094644•B•C22 and RTI2018'093940'B•I00•UNED•Universidad Nacional de Educación a======Distancia (UNED).
4 citations
TL;DR: The latest recent contributions to azole chemistry are reported, in particular, those in which theoretical studies have been performed.
Abstract: Azoles are a family of five-membered azacyclic compounds with relevant biological and pharmacological activity. Different subclasses of azoles are defined depending on the atomic arrangement and the number of nitrogen atoms present in the ring: pyrazoles, indazoles, imidazoles, benzimidazoles, triazoles, benzotriazoles, tetrazoles and pentazoles. The complete characterization of their structure and the knowledge about their crystal packing and physical and chemical properties are of vital importance for the advancement in the design of new azole-containing drugs. In this review, we report the latest recent contributions to azole chemistry, in particular, those in which theoretical studies have been performed.
2 citations