Synthesis of Geminal Bis- and Tetrakisphosphonate Ester Derivatives and Their Coordination Behavior Towards Ca(II) Ions

The preparation and thorough characterization of a variety of (arylmethylene)phosphonate ester derivatives (S1-S7) as well as derived geminal bisphosphonate (BP) ester ligands (L1-L7) is presented. Subsequent complexation reactions of CaCl2 with selected BPs (L1-L3) and a known aliphatic tetrakisphosphonate ester (L8) yield the respective Ca(II) coordination compounds [Ca(H2O)(2)(L1-L3)(2)]Cl-2 (C1-C3) and [Ca(L8)Cl-2](n) (C4) for potential future application as multi-delivery systems in osteoporosis treatment. Obtained SCXRD and H-1 DOSY-NMR data provide a detailed insight into their solid- as well as solution-state structures extending the so far scarcely found X-ray studies on geminal BP-supported Ca(II) complexes.

Automated summary

This study presents the preparation and characterization of various (arylmethylene)phosphonate ester derivatives and derived geminal bisphosphonate ester ligands. The complexation reactions with calcium ions resulted in coordination compounds that have potential applications as multi-delivery systems in osteoporosis treatment. The obtained experimental data provide detailed insight into the solid-state and solution-state structures.