Structural insight into the anion–water cluster: stabilised by alcohol and carboxylic acid containing tripodal ligand

Abstract

A new flexible N-bridged, unsymmetrical, water-soluble tripodal ligand (L) bearing alcohol and carboxylic acid groups has been synthesised and its solid-state interaction with anions has been investigated. The fully deprotonated ligand encapsulates a sodium cation in a half cryptand bowl-shaped cavity (1). The chloride complex 2, contains a cyclohexane-like water cluster incorporating ligand OH groups. However, complexes with bromide and nitrate (3 and 4) are dimeric. Tetrahedral clusters containing two water molecules and two anions were found in complexes 3 and 4. Perchlorate complex 5 forms perchlorate–methanol adducts. Complex 1 forms a hydrophilic cation–water channel and complexes 2–4 form anion–water channels between the hydrophobic layers of the naphthalene moieties. Complexes 2, 5 and 3, 4 are isostructural in nature having similar packing structures.