Intramolecular Hydrogen-bonding Network Research Articles

An investigation of the relationship between sweetness and intramolecular hydrogen-bonding networks in hexuloses using the semiempirical molecular orbital method, AM1

An investigation of the relationship between sweetness and intramolecular hydrogen-bonding networks in hexuloses using the semiempirical molecular orbital method, AM1

Proton and zinc(II) complexes of 2-(polyhydroxyalkyl)thiazolidine-4-carboxylic acid derivatives

The protonation and zinc-ion co-ordination equilibria of 2-(polyhydroxyalkyl) thiazolidine-4-carboxylic acid derivatives have been studied by potentiometric titration in the range pH 1.5–8. In most cases the formation of complexes with a metal-to-ligand ratio of 1 : 2 was demonstrated, but at above pH 6 mixed-ligand complexes involving hydroxide-ion co-ordination were also observed. The protonation and complex-formation constants were shown to depend on the structure of the polyhydroxy chains. In the case of the protonation constants this is due to the rearrangement of the intramolecular hydrogen-bonding network, while the complex-formation constants depend on the conformation of the OH groups on the first carbon atoms of the polyol chains.

Co-operative and competitive hydrogen bonding in sucrose determined by SIMPLE 1H n.m.r. spectroscopy

SIMPLE1H n.m.r. measurements of isotope-shifted resonance for hydroxy groups in sucrose show that hydrogen bonding in solution is different from that observed in the solid state viz. there are two inter-residue hydrogen bonds in competition for one acceptor group (i.e. OH1′⋯ O2 vs.OH3′⋯ O2) and an intramolecular hydrogen-bond network that is nucleated by the inter-residue hydrogen bonds.