Metal ion dependent molecular inclusion chemistry: Inclusion of p-toluenesulfonate and p-nitrophenolate within the structure of coordinated 1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraazacyclodod ecane

摘要

The pendant donor macrocyclic ligand 1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraazacyclodod ecane ((S)-thphpc12) has been synthesized in quantitative yield from cyclen (1,4,7,10-tetraazacyclododecane) and (2S)-(+)-3-phenoxy-1,2-epoxypropane. An X-ray diffraction study supports the result of molecular orbital calculations in showing that complexation with hydrated cadmium(II) diperchlorate produces an approximately square-antiprismatic complex in which the metal ion is located between a plane containing the four nitrogen atoms and a plane containing the four oxygen atoms. As a consequence of this the four phenoxymethyl moieties, each attached to one of the four N-O chelate rings, juxtapose to form a substantial empty cavity allowing the complex to act as a molecular receptor. inclusion complexes have been formed from this complex in which either a p-toluenesulfonate or p-nitrophenolate anion has entered the cavity. An X-ray crystallographic study of [Cd-((S)-thphpc12)(p-toluenesulfonate)]ClO4 shows that the guest anion is retained within the cavity by four hydrogen bonds to the group of hydroxyl moieties associated with the ligand. C-13 NMR and conductivity studies indicate that this inclusion complex retains its integrity in DMSO or DMF solution. Parallel studies have been conducted with [Pb((S)-thphpc12)](ClO4)(2) indicating that the corresponding inclusion complexes are of lower stability. [References: 24]