The theorem of matching proton affinities (PA) has been widely used in the analysis of hydrogen bonds. However, most experimental and theoretical investigations have to cope with the problem that the variation of the PA of one partner in the hydrogen bond severely affects the properties of the interface between both molecules. The B3LYP/d95+(d,p) analysis of two hydrogen bonds coupled by a 5-me...

Evidence from proteins and peptides supports the conclusion that intrapeptide hydrogen bonds stabilize the folded form of proteins. Paradoxically, evidence from small molecules supports the opposite conclusion, that intrapeptide hydrogen bonds are less favorable than peptide-water hydrogen bonds. A related issue-often lost in this debate about comparing peptide-peptide to peptide- water hydroge...

Activation of the C-F bond of benzylic fluorides was achieved using 1,1,1-tris(hydroxymethyl)propane (2) as a hydrogen bond-donating agent. Investigations demonstrated that hydrogen bond-donating solvents are promoting the activation and hydrogen bond-accepting ones are hindering it. However, the reaction is best run under highly concentrated conditions, where solvents cannot interfere with the...

Hydrogen bonding occurs when an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one, so that it may be considered to be acting as a bond between them [99]. Typically hydrogen bonding occurs where the partially positively charged hydrogen atom lies between partially negatively charged oxygen and/or nitrogen atoms, but is also found elsewhere, such as between fl...

In the crystal of the title salt, 2C(2)H(8)N(+)·C(6)H(4)O(8)S(2) (2-), the anion lies on a center of inversion. The dimethyl-ammonium cation forms one N-H⋯O hydrogen bond and another bifurcated N-H⋯O hydrogen bond. The hy-droxy group links with the sulfonyl group via an inter-molecular O-H⋯O hydrogen bond. These N-H⋯O and O-H⋯O hydrogen bonds generate a three-dimensional network.

A synthetic strategy for constructing ionic hydrogen-bonded materials by combining perhalometallate anions with cations able to serve as hydrogen bond donors is presented. The approach is based on identification of well defined hydrogen bond acceptor sites on the anions by a combination of experimental and theoretical approaches. Selective population of these sites by hydrogen bond donors has t...

in the present work, dft calculations are employed to obtain the optimized structures of 4-acyl pyrazolone tautomers (19 tautomers) using b3lyp/6-311++g** calculations. inaddition, molecular parameters, ir frequencies and relative energies are extracted for alltautomers. the existence of aromatic ring, keto tautomer (versus enol tautomer), n-h bond(versus c-h bond) and c=n double bond (versus n...

Hydrogen bonds are weak, generally intermolecular bonds, which hold much of soft matter together as well as the condensed phases of water, network liquids, and many ferroelectric crystals. The small mass of hydrogen means that they are inherently quantum mechanical in nature, and effects such as zero-point motion and tunneling must be considered, though all too often these effects are not consi...