Diversity of the Supramolecular Association Modes Between the Dicarboxylic Host Compound 1,1′-Binaphthyl-2,2′-dicarboxylic Acid and the First Five Representatives of the Homologous Series of Aliphatic Monocarboxylic Acids as Guests

Abstract

The solved structures of clathrates between 1,1′-binaphthyl-2,2′-dicarboxylic acid (BNDA) as host and acetic, propionic and butyric acid guests together with previously determined clathrates of BNDA with formic and acetic acid testify that each of the first four representatives of the homologous series of aliphatic monocarboxylic acids has its own association mode with the dicarboxylic host. Acetic acid forms a clathrate specific for it at room temperature and gives a solvate isostructural with the propionic acid inclusion complex at 60 °C. The host–guest complex of butyric acid is isostructural with the clathrate of valeric acid. As a matter of principle, it is shown that (1) the larger the monocarboxylic acid molecule the greater is its ability to disintegrate infinite chains of H-bonded host molecules characteristic for a guest-free host compound—formic acid is not able to cut host chains to smaller fragments and attaches itself to them, acetic acid tends to cut chains to dimers which are then associated to circular tetramers through H-bonds of guest molecules, propionic acid disintegrates host chains to linear tetramers while butyric as well as valeric acid cut the chains to dimeric units. (2) The higher the crystallization temperature of the dicarboxylic host from solutions in acetic acid the stronger is the interaction between the host molecules in the obtained crystal modification.