On intramolecular and intermolecular hydrogen bonding

Intramolecular hydrogen bonding is often an important contribution to the overall hydrogen bonding in fluid systems, especially in systems of biological interest. Of interest is the case of very dilute systems in inert solvents where intermolecular hydrogen bonding is absent and the only observed hydrogen bonds are the intramolecular ones. The objective of this note is to present the necessary formalism in the frame of the lattice-fluid/hydrogen-bonding (LFHB) model1 for studying fluid systems with both intermolecular and intramolecular hydrogen bonds. For simplicity, we will confine ourselves to the case of molecules with one donor group (such as –OH) and x equivalent proton acceptor sites (such as ether oxygen –O–) per molecule. This type of system (polyethoxyalcohols) is of direct interest to the IUPAC project on alkanol–alkane–ether systems as they involve the same type of interactions, and is of key importance in the study of non-ionic surfactants. The formalism can easily be extended to more complex cases.