Steric influence of adamantane substitution in tris-urea receptor: encapsulation of sulphate and fluoride-water cluster

Abstract

Abstract : Tris(2-aminoethyl)amine (tren)-based bulky adamantane group-substituted tris-urea (L) has been developed as the potential tripodal receptor exhibiting strong binding affinities towards small spherical fluoride anion as well as large tetrahedral sulphate anion in its neutral and protonated form, respectively. Structural elucidation reveals that the divalent sulphate ion is fully engulfed inside the complementary space created by two face-to-face oriented symmetry-independent protonated receptors, whereas the smaller fluoride ion is encapsulated as fluoride-water cluster (F --H 2O) assemblage within the neutral unimolecular capsular assembly of receptor L. GRAPHICAL ABSTRACT : SYNOPSIS Entrapment of Sulphate and fluoride-water cluster within the rigid cavity of adamantine-substituted tris-urea. [Figure not available: see fulltext.].