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-tetraazacyclododecane.
The pendant donor macrocyclic ligand 1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraazacyclododecane ((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)]ClO(4) shows that the guest anion is retained within the cavity by four hydrogen bonds to the group of hydroxyl moieties associated with the ligand. (13)C 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)](ClO(4))(2) indicating that the corresponding inclusion complexes are of lower stability.
Smith
Christopher B.
CB
Department of Chemistry, The Flinders University of South Australia, GPO Box 2100, Adelaide, SA 5001, Australia, and the Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia.
Wallwork
Kia S.
KS
Weeks
Jennifer M.
JM
Buntine
Mark A.
MA
Lincoln
Stephen F.
SF
Taylor
Max R.
MR
Wainwright
Kevin P.
KP