Water-soluble Ag(I)-based coordination polymers obtained by anion-directed self-assembly of various AgX salts and a phosphabetaine derived from 1,3,5-triaza-7-phophaadamantane

Abstract A new, solvent-free method has been developed for the synthesis of 7-(2-carboxy-ethyl)-1,3,5-triaza-7-(phosphoniatricyclo)[3.3.1.13,7]decane (L). It is disclosed here that 1,3,5-triaza-7-phosphaadamantane (PTA) reacted cleanly with acrylic acid in a planetary ball mill resulting in 88 % yield of the corresponding P-carboxy-ethyl derivative, in striking contrast to the complete failure of the synthesis of the same product from the same reactants in solution. The resulting phosphabetaine, L gave crystalline 1D coordination polymers with Ag+-salts bearing PF 6 - , p-toluenesulfonate (tos) and trifluoromethanesulfonate (OTf) anions. According to single-crystal X-ray diffraction studies, the solid state structures of these coordination polymers were decisively influenced by the anion of the Ag+-salt used for synthesis. In addition to single-crystal X-ray diffraction, the new Ag-based coordination polymers, namely [Ag(μ3-L-κ3N:O:O’)]n(PF6)n, (1), [Ag(tos)(μ3-L-κ3N:N:O)]n×nH2O, (2), and [Ag(OTf)(μ3-L-κ3N:O:O’)]n, (3) were characterized also by elemental analysis, 1H-, 13C-, and 31P-NMR, as well as IR spectroscopies and with ESI mass spectrometry. Determination of the hydrodynamic diameter of the phosphabetaine ligand and its Ag+-complexes by diffusion NMR measurements revealed, that upon dissolution in water these compounds did not retain their polymeric nature.