Molecular organization and solution properties of N-substituted aminomethane-1,1-diphosphonic acids

The crystal structures of N-n-pentylaminomethane-1,1-diphosphonic (1), N-py rrolidinomethane-1,1-diphosphonic (2), N-(3-carboxy-2-pyridyl)aminomethane- 1,1-diphosphonic (3a) and N-(5-methyl-2-pyridyl)aminomethane-1,1-diphosphon ic (3c) acids are determined and discussed with respect to their packing pa tterns and solid state organization. The molecular association and the poss ible aggregate forms in solution, resulting from the supramolecular feature s of these materials, are considered. The solution UV and NMR studies are f ocused on the N-2-pyridylaminomethane-1,1-diphosphonic acids 3a-e in order to establish the influence of the structural changes in passing from 3- to 5- or 6-pyridyl substituted aminomethane-1,1-diphosphonic acids on their ge neral complexation properties.