The interplay and strength of the π⋯HF, C⋯HF, F⋯HF and F⋯HC hydrogen bonds upon the formation of multimolecular complexes based on CH⋯HF and CH⋯HF small dimers.

The conception of this theoretical research was idealized aiming to unveil the intermolecular structures of complexes formed by acetylene or ethylene and hydrofluoric acid. At light of computational calculations by using the B3LYP/6-311++G(d,p) method, the geometries of the CH⋯(HF), CH⋯2(HF), CH⋯4(HF), CH⋯(HF), CH⋯2(HF) and CH⋯4(HF) hydrogen-bonded complexes were fully optimized. Moreover, the Post-Hartree-Fock calculations MP2/6-311++G(d,p), MP2/aug-cc-pVTZ, MP4(SDQ)/6-311++G(d,p) and CCSD/6-311++G(d,p) also were also used.

Structure, energy, vibrational spectrum, and Bader's analysis of π···H hydrogen bonds and H(-δ)···H(+δ) dihydrogen bonds.

In this paper, the intermolecular structural study asserted by the vibrational analysis in the stretch frequencies of hydrogen bonds (π···H) and dihydrogen bonds (H(-δ)···H(+δ)) have definitively been revisited by means of calculations carried out by Density Functional Theory (DFT) and topological parameters derived from the classic treatise of the Quantum Theory of Atoms in Molecules (QTAIM). As a matter of fact the π···H hydrogen bond is formed between the hydrofluoric acid and the C≡C bond of the acetylene, but the QTAIM calculations revealed a distortion in this interaction due to the formation of the ternary complex C(2)H(2)···2(HF). Although the π bonds of ethylene (C(2)H(4)), propylene (C(2)H(3)(CH(3))), and t-butylene (C(2)H(2)(CH(3))(2)) are considered proton acceptors, two hydrogen-bond types--π···H and C···H--can be observed.

Solid dispersions of imidazolidinedione by PEG and PVP polymers with potential antischistosomal activities.

Solid dispersions have been used as a strategy to improve the solubility, dissolution rate, and bioavailability of poor water-soluble drugs. The increase of the dissolution rate presented by (5Z)-3-(4-chloro-benzyl)-5-(4-nitro-benzylidene)-imidazolidine-2,4-dione (LPSF/FZ4) from the solid dispersions is related to the existence of intermolecular interactions of hydrogen bond type (>N-H···O<) between the amide group (>N-H) of the LPSF/FZ4 and the ether group (-O-) of the polyethyleneglycol polymer, or the carbonyl (C=O) of the polyvinylpyrrolidone polymer (PVP). The intensity of these interactions is directly reflected in the morphology acquired by LPSF/FZ4 in these systems, where a new solid phase, in the form of amorphous aggregates of irregular size, was identified through scanning electron microscopy and confirmed in the characterizations achieved using X-ray diffraction and thermal analysis of DSC.

Design, synthesis and cruzain docking of 3-(4-substituted-aryl)-1,2,4-oxadiazole-N-acylhydrazones as anti-Trypanosoma cruzi agents.

Research in recent years has demonstrated that the Trypanosoma cruzi cysteine protease cruzain (TCC) is a valid chemotherapeutic target, since inhibitors of this protease affect the pathology appropriately. By exploring the N-acylhydrazones (NAH) as privileged structures usually present in antiparasitic agents, we investigated a library of 16 NAH bearing the 3-(4-substituted-aryl)-1,2,4-oxadiazole scaffold (NAH 3a-h, 4a-h). The in vitro bioactivity against epimastigote and trypomastigote forms of T.

Novel nitrofurazone derivatives endowed with antimicrobial activity.

The N-alkylated derivatives from nitrofurazone were synthesised and evaluated in vitro for their efficacy as antimicrobial agents against representative strains, including methicillin-resistant Staphylococcus aureus (MRSA). The derivative 2a demonstrated greater activity than the prototype and was comparable to currently used antimicrobial drugs.

The electronic structure of the C2H4O...2HF tri-molecular heterocyclic hydrogen-bonded complex: a theoretical study.

The geometries of three isomers of the C2H4O...