W0019

Supramolecular Crown Ether Arrays and Other Crystal Engineered Molecules. Abraham Clearfield and C.V.K. Sharma, Dept. of Chemistry, Texas A&M University, College Station, Texas 77842-3012

Phosphonic acids have been shown to form very strong hydrogen bonds and therefore are excellent candidates for synthesis of crystal engineered or designed structures. We have prepared a series of phosphonic acids from crown ethers. By removing a portion of the protons from the acid molecules, self-polymerization into linear arrays has been obtained. The structures resemble a string of leaves attached to a twig or stem and have been termed "Macrocyclic Leaflets."¹ Examples of hydrogen bonded and metal atom covalently bonded chains or combinations of the bonding types will be presented.

A second ligand, nitrilotris(methylene phosphonic acid), N(CH₂PO₃H₂), has been used to prepare designed structures. Removal of a proton from the acid by phenanthrolines results in the formation of a hexagonal planar array encapsulating the amine. Strong hydrogen bonds directed perpendicular to the hexagonal planar array then links the layers into a 3-D tunnel type structure.² Reaction of the trisphosphonic acid with divalent metals forms a single structure irrespective of the metal as dictated by the H-bonding of the ligand.

1. C.V.K. Sharma and A. Clearfield J. Am. Chem. Soc. 122, 1558 (2000).

2. C.V.K. Sharma and A. Clearfield J. Am. Chem. Soc. 122, 4395 (2000).

3. C.V.K. Sharma, A. Clearfield, et al. J. Am. Chem. Soc. in press for March 2001.