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Hydrogen bond
About: Hydrogen bond is a research topic. Over the lifetime, 57701 publications have been published within this topic receiving 1306326 citations.
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TL;DR: Examination of the structure of the binary complex of the glutamate dehydrogenase has led to a proposal for the catalytic activity of the enzyme, which involves Asp165 as a general base and an enzyme-bound water molecule, hydrogen-bonded to an uncharged lysine residue, Lys125, as an attacking nucleophile in the reaction.
198 citations
TL;DR: It is demonstrated that unsaturated acyl phosphonates are excellent hydrogen-bond acceptors in enantioselective organocatalysis by employing chiral thioureas or squaramides as catalysts, thereby providing successful relay of the chirality from the catalyst to the substrate.
Abstract: This study demonstrates that unsaturated acyl phosphonates are excellent hydrogen-bond acceptors in enantioselective organocatalysis. By employing chiral thioureas or squaramides as catalysts, the acyl phosphonates are effectively coordinated and activated by hydrogen bonding, thereby providing successful relay of the chirality from the catalyst to the substrate. A variety of highly stereoselective conjugate additions to α,β-unsaturated acyl phosphonates were performed, using different carbon-based nucleophiles such as oxazolones, indoles, and 1,3-dicarbonyl compounds. The reaction concept has been developed to be a double nucleophilic reaction, and it is shown that the acyl phosphonates serve as masked ester or amide equivalents, which upon quenching with the second nucleophile generate the parent structures in situ. Accordingly, formal C−C bond formation reactions of ester and amide substrates are achieved, affording a broad spectrum of optically active conjugate adducts in good yields and excellent ena...
197 citations
TL;DR: The results show that the nonclassical contributions to hydrogen bonding are spatially localized, involving only the H atom and its two nearest neighbors.
Abstract: The interacting quantum atoms approach [IQA, as presented by Blanco et al., J. Chem. Theory Comput. 1, 1096 (2005)] is applied to standard hydrogen bonded dimers. IQA is an interpretation tool based on a real space energy decomposition scheme fully consistent with the quantum theory of atoms in molecules. It provides a partition of every physical term present in the Hamiltonian into atomic and interatomic contributions. The procedure is orbital-free and self-contained, needing neither external references nor artificial intermediate states. Binding is the result of a competition between the destabilizing deformations suffered by the interacting fragments upon interaction and the stabilizing interaction energy itself. According to IQA, there is no incompatibility between the prevalent electrostatic image of hydrogen bonded systems and that favoring important covalent contributions. Depending on how we gather the different energetic terms, we may recover electrostatic or covalent pictures from the same under...
197 citations
TL;DR: Multiple crystal structures of MR (NR3C2) bound to both agonist and antagonists are reported, revealing that maximal receptor activation involves an intricate ligand-mediated hydrogen bond network with Asn770 which serves dual roles: stabilization of the loop preceding the C-terminal activation function-2 helix and direct contact with the hormone ligand.
197 citations
TL;DR: This first principles based molecular modeling investigation of the possible role of the side chain in effecting proton transfer in the short-side-chain perfluorosulfonic acid fuel cell membrane under minimal hydration conditions provides a baseline for molecular results that can be used to assess the impact of changes of polymer chemistry on proton conduction.
Abstract: Presented here is a first principles based molecular modeling investigation of the possible role of the side chain in effecting proton transfer in the short-side-chain perfluorosulfonic acid fuel cell membrane under minimal hydration conditions. Extensive searches for the global minimum energy structures of fragments of the polymer having two pendant side chains of distinct separation (with chemical formula: CF3CF(O(CF2)2SO3H)(CF2)nCF(O(CF2)2SO3H)CF3, where n = 5, 7, and 9) with and without explicit water molecules have shown that the side chain separation influences both the extent and nature of the hydrogen bonding between the terminal sulfonic acid groups and the number of water molecules required to transfer the proton to the water molecules of the first hydration shell. Specifically, we have found that fully optimized structures at the B3LYP/6-311G** level revealed that the number of water molecules needed to connect the sulfonic acid groups scaled as a function of the number of fluoromethylene grou...
197 citations