Synthesis, Structure, And Properties Of A New Co(Ii) Diphosphonate Based On Auxiliary Ligand 2,2 '-Bipyridine

The example of Co(II)-N-heterocyclic complex based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C (OH)(PO3H2)(2)), namely [Co-2(H3L)(2)(2,2'-bipy)(2)] 1, has been solvothermally isolated using the second ligand 2,2'-bipyridine (2,2'-bipy) and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, and thermal gravimetric analyses. The single-crystal X-ray diffractions show that complex 1 possesses a 0-D structure built from binuclear unit [Co-2(O-P-O)(2)] by mu(2)-(O-P-O) bridge. Then, H-bonding and pi-pi stacking interactions further expand this 0-D structure into a 3-D supramolecular framework. Fluorescent measurements reveal that the maximum emission peak is centered at 421.5 nm, mainly deriving from intraligand pi*-pi transition state of the second ligand 2,2'-bipy (lambda(em) = 419.5 nm, lambda(ex) = 235 nm). Magnetism data indicate that 1 exhibits ferromagnetic behavior within binuclear Co(II) unit via mu(2)-(O-P-O) bridge in syn-anti mode.