Anion Dependent Water Clusters Encapsulated Inside a Cryptand Cavity

Abstract

A series of water clusters encapsulated inside a cryptand cavity were obtained in the cryptand-acid supramolecular adducts of [(H2O)2⊂(H6L)][H2PO4]6(H2O)3 (1·3H2O), [(H2O)3⊂(H6L)][H2PO4]6(H2O)11 (2·11H2O), [(H2O)3⊂(H6L)][CH3(C6H4-p)SO3]6(H2O)4 (3·4H2O), and [(H2O)6⊂(H6L)][SO4]3(H2O)13 (4·13H2O) (L = N[(CH2)2NHCH2(C6H4-p)CH2NH(CH2)2]3N). In 1 and 2, H6L6+ is hydrogen bonded to six H2PO4− through its protonated nitrogen atoms to form two (O···H−N−H···)3 rings at two poles of H6L6+. A well encapsulated water dimer, and a circle- and cage-shaped trimer of [H2PO4]3 are formed in 1. A well encapsulated circular water trimer and a bowl-shaped trimer of [H2PO4]3 are formed in 2. In 3, the steric effect of the tolyl group of [CH3(C6H4-p)SO3]− causes a change in the conformation of H6L6+ to generate a favorable environment for a linear water trimer inside the crystand cavity. In 4, H6L6+ bonds three SO42− anions through the protonated nitrogen atoms at the one pole, and a quasi-prismatic hexamer water cluster is fo...