The molecular properties of heterocyclic and homocyclic hydrogen-bonded complexes evaluated by DFT calculations and AIM densities

Oliveira, Boaz G.; Araújo, Regiane C. M. U.; Carvalho, Antônio B.; Ramos, Mozart N.

doi:10.1007/s00894-008-0380-2

Cited by 39 publications

(11 citation statements)

References 64 publications

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“…By taking into account the ΔE C values, the (b) complex is twice more stable than (c). In conformity with recent studies about the formation of heterocyclic and homocyclic complexes 66 , as expected the (a) complex presented the lower intermolecular energy, whose value is 2.23 kJ mol -1 . Not only in terms of intermolecular energies, but the importance of the transference of charge density between the HOMO-LUMO frontier molecular orbital pairs led the necessity for quantifying the charge transfer amount, namely as δq.…”

Section: Intermolecular Energiessupporting

confidence: 91%

Blue-Shifting Hydrogen Bonds and Secondary Interactions in the C3h6…hcf3, C2h4o…hcf3 and C2h4s…hcf3 Cyclic Complexes

Oliveira

2011

J. Chil. Chem. Soc.

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In this article, a theoretical study of molecular properties of small cyclic systems is presented. Through the calculations performed at the B3LYP/6-311++G(d,p) level of theory, the optimized geometries of the C 3 H 6 ···HCF 3 , C 2 H 4 O···HCF 3 and C 2 H 4 S···HCF 3 hydrogen-bonded complexes were determined. By analyzing the structural parameters, it was observed a contraction of the C-H bond length of the fluoroform (HCF 3 ). As such, the examination of the harmonic infrared spectrum accused the existence of a blue-shift effect in this bond, once its stretch frequency is displaced to upward values accompanied by a significant diminishing on the absorption intensity. In the purpose to comprehend this vibrational phenomenon, topological parameters computed at the light of the Quantum Theory of Atoms in Molecules (QTAIM) were also used. An interesting aspect is the non-linearity deviation on the hydrogen bonds (O···H) and (S···H) due to the formation of a secondary interaction (H

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Section: Intermolecular Energiessupporting

confidence: 91%

Blue-Shifting Hydrogen Bonds and Secondary Interactions in the C3h6…hcf3, C2h4o…hcf3 and C2h4s…hcf3 Cyclic Complexes

Oliveira

2011

J. Chil. Chem. Soc.

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“…Owing to the drastic vibrational displacement in the N-H d bond, ideally the proton donor function of this bond can be then validated upon formation of complex I. On the other hand, a red-shift effect of −81.9 cm −1 is observed in the N-H c bond of complex II with an absorption intensity ratio of 278.2, meaning the appearance of traditional hydrogen bond profiles [93], but notably here with the aziridine as proton donor. Moreover, complex III is quite unique, with no vibrational displacements found in NH 3 , although red-shifts of −5.6 cm −1 in the N-H d , N-H e , and N-H f bonds were computed, and a large blue-shift of +88 cm −1 was identified in the C′-H b bond of the aziridine ring.…”

Section: Infrared Harmonic Spectrum: Red-shifting and Blue-shifting Hmentioning

confidence: 99%

Theoretical aspects of binary and ternary complexes of aziridine⋯ammonia ruled by hydrogen bond strength

Oliveira

Araújo

2011

J Mol Model

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B3LYP calculations, ChelpG atomic charges, and quantum theory of atoms in molecules (QTAIM) integrations were used to investigate the binary (1:1) and ternary (1:2) hydrogen-bonded complexes formed by aziridine (1) and ammonia (2). In a series of analysis, geometry data, electronic parameters, vibrational oscillators, and topological descriptors were used to evaluate hydrogen bond strength, and additionally to determine the more prominent molecular deformations upon the formation of C(2)H(5)N···NH(3) (1:1) and C(2)H(5)N···2NH(3) (1:2) systems. Taking a spectroscopic viewpoint, results obtained from analysis of the harmonic infrared spectrum were examined. From these, new vibrational modes and red- and blue-shifts related to the stretch frequencies of either donors or acceptors of protons were identified. Furthermore, the molecular topology of the electronic density modeled in accord with QTAIM was absolutely critical in defining bond critical points (BCP) and ring critical points (RCP) on the heterocyclic structures. Taking all the results together allowed us to identify and characterize all the N···H hydrogen bonds, as well as the strain ring of the aziridine and its stability.

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“…By taking into account the virial theorem [17], G and U idealize the kinetic (always positive) and potential (always negative) energy density functions. Then, positive values of ∇ 2 ρ indicate a depletion of electronic potential energy density at BCP in favor of the kinetic energy because it outweighs the potential one, showing a concentration of electronic charge in separated nuclei [51][52][53]. …”

Section: Qtaim Parameters and Intramolecular Hydrogen Bondsmentioning

confidence: 99%

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

2016

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Abstract:The conformational preferences of benznidazole were examined through the application of DFT, PCM and QTAIM calculations, whose results were compared with crystallography data. The geometries were fully optimized with minimum potential energy surface by means of the Relaxed Potential Energy Surface Scan (RPESS) at AM1, followed by the B3LYP/6-311++G(d,p) theoretical level. As a result, the s-cis conformation (1C) was shown to be more stable (4.78 kcal¨mol´1) than s-trans (1T). The Quantum Theory Atoms in Molecules (QTAIM) was applied in order to characterize the (N-H¨¨¨O=N) and (C-H¨¨¨=N) intramolecular hydrogen bonds. The simulation of solvent effect performed by means of the implicit Polarized Continuum Model (PCM) revealed great results, such as, for instance, that the conformation 1W is more stable (23.17 kcal¨mol´1) in comparison to 1C. Our main goal was stressed in the topological description of intramolecular hydrogen bonds in light of the QTAIM approach, as well as in the solvent simulation to accurately obtain an important conformation of benznidazole.

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The molecular properties of heterocyclic and homocyclic hydrogen-bonded complexes evaluated by DFT calculations and AIM densities

Cited by 39 publications

References 64 publications

Blue-Shifting Hydrogen Bonds and Secondary Interactions in the C3h6…hcf3, C2h4o…hcf3 and C2h4s…hcf3 Cyclic Complexes

Blue-Shifting Hydrogen Bonds and Secondary Interactions in the C3h6…hcf3, C2h4o…hcf3 and C2h4s…hcf3 Cyclic Complexes

Theoretical aspects of binary and ternary complexes of aziridine⋯ammonia ruled by hydrogen bond strength

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

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