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Using density functional theory, polyols were used as model ligands for Cu+/Cu2+ complexes to study the role of the hydrogen bond network on the metal binding affinity. In addition to the gas phase studies, the calculations were performed in 1‐decanol and DMSO solvents. The Cu2+ complexes were the most stable complexes with the highest bond dissociation energies (BDE). The presence of three H‐bonds in the first shell increased BDE values up to 17.99 and 57.07 kcal/mol for Cu+ and Cu2+ complexes in the gas phase, respectively, whereas the presence of another three H‐bonds in the second shell increased BDE values up to 7.27 and 24.35 kcal/mol for Cu+ and Cu2+ complexes in the gas phase, respectively. Therefore, this H‐bond network caused, for example, a more stable Cu+ complex with a formation constant of 1.4 × 1017 times. The natural bond orbital (NBO), atoms in molecules (AIM), and reduced density gradient (RDG) analyses showed that the intramolecular hydrogen bond network led to the enhancement of metal‐binding affinity. [ABSTRACT FROM AUTHOR]

Density functional theory method and B3LYP/6‐311++G(d,p) level of theory were used to determine the acidity of α‐carbon in the hydroxyl derivatives of beta diketones in the gas phase. An investigation of acidity strength in the gas phase indicates that α‐carbon of hydroxyl derivatives of beta diketones become stronger acids than the α‐carbon of beta diketone itself as their conjugate bases gain more stability via both enolate and hydrogen bond formation. Natural bond orbital and quantum theory of atoms in molecules analyses also confirm the role of hydrogen bond interactions on increasing the acidity of α‐carbon of hydroxyl derivatives of beta diketones. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) was used to investigate the acidity of the various silica alkyl sulfonic acids. In this regard, cluster models with various alkyl spacer lengths were selected to mimic the surface of silica gel. The effects of distance from the surface and the role of hydrogen bond (H–bond) on the ΔHacidityvalues of these catalysts were investigated. DFT calculations revealed that a notable gap of ΔHacidityvalues exists between the structures considering lateral hydrogen bonding with the surface of the silicaHB structureand the structures with omitted surface interactions (non-HB structures). Natural bonding orbital (NBO) and quantum theory of atoms in molecules (QTAIM) analyses were carried out to obtain detailed information about the nature of the H–bonds. [ABSTRACT FROM AUTHOR]

Silica gelâ€confined ionic liquid (IL) is a class of heterogeneous catalysts with broad catalytic applications. Leaching of the IL from the surface of the support is the major drawback of these catalysts, which reduce the catalyst efficiency during the chemical reactions. To investigate the effect of the hydrogen bonding on the leaching phenomena, the interaction between the 1â€ethylâ€3â€methylimidazoliumâ€based IL with various anions (Clâˆ', Brâˆ', HSO4âˆ', NO3âˆ', BF4âˆ', and PF6âˆ') and the surface of the silica gel were studied using density functional theory. Hence, a hydroxylated cageâ€like cluster of silica gel, Si4O6(OH), was selected to mimic the surface. The values of Î'Einteraction show that ILs with halogen counter ions have stronger interactions than that of the IL with BF4âˆ' and PF6âˆ' counter ions. We also carried out stirringâ€'filtration method for some prepared samples of IL@silica to experimentally explore the leaching phenomena. The results show good agreement with computational achievements. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) method and B3LYP/6-311++G(d,p) basis set were used to determine coordination geometries, binding strength, and metal ion affinity (MIA) for interaction of 2′-deoxythymidine (dT) with alkali metal cations including , and . Calculations demonstrated that the interaction of dT with these cations is tri-coordinated η (O2, O4′, O5′). Among these cations, cation exhibited the most tendency for interaction with dT. Cations via their interaction with dT can affect the N-glycosidic bond length, the values of pseudorotation of the sugar ring, the orientation of base unit with respect to sugar ring and the acidity of O5′H, O3′H, and N3H groups in 2′-dT nucleoside. Natural bond orbital (NBO) analysis was performed to calculate the charge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules (QTAIM) was also applied to determine the nature of interactions. It was shown that in these complexes, (dT-, dT-, and dT-), the bonds are an electrostatic (closed-shell) interaction in the nature. [ABSTRACT FROM AUTHOR]