Water clusters with anion templates in cucurbit[6]uril supramolecular pseudorotaxanes

Abstract

Two types of anion water clusters have been observed in cucurbit[6]uril based pseudorotaxanes with two kinds of guests. (COO−)2(C2H5OH)2(H2O)4 anion water clusters and (H2O)2 water clusters are formed with the carboxylate groups of the guest 1, 1′-(hexane-1, 6-diyl) dipyridinium-4-carboxylate inner salt (HDPC) and connect the pseudorotaxane molecules to form 3D networks. Anion water clusters Cl2−(H2O) with independent water molecules are observed in the crystal structure of the pseudorotaxane with the guest 1, 1′-(hexane-1, 6-diyl) dipyridinium-4-hydroximic acid dichloride (HDHD). The results revealed that terminal groups of the guests, the solvents and the anions species in cucurbit Arunachalam and Ghosh (2011) uril pseudorotaxanes could affect the structures and the sizes of water clusters.