Coordination abilities of piperyd-1-yl-methane-1,1-diphosphonic acids towards zinc(II), magnesium(II) and calcium(II): Potentiometric and NMR studies

Aminoalkylbis(phosphonates): Their Complexation Properties in Solution and in the Solid State

“…The lower one is usually ascribed to the last deprotonation of the bis(phosphonic acid) moiety, and the last deprotonation occurs from the amino group. [18] The last proton is bound to the nitrogen atom in almost all poly(aminophosphonates). [19] This assignment can be supported by the crystal structure of the tris(ammonium) salt of H 4 meth (see below), whose structure contains a fully deprotonated bis(phosphonic acid) group, whereas the amino group remains protonated.…”

“…[22] Therefore, the presence of these complicated structures in solution is expected as well. [18] Unfortunately, the complexity of the studied systems did not allow us to take these multinuclear/polymeric complexes into account during the refinement of the potentiometric data.…”

Extracellular Ca2+-dependent enhancement of cytocidal potency of zoledronic acid in human oral cancer cells

“…The chelator EGTA abrogates the influence of Ca 2 þ on ZA-induced growth inhibition, probably by competing with the bisphosphonate for Ca 2 þ complexation. Because the phosphonate groups allow effective chelation of metal ions (Matczak-Jon et al, 2006), it may be speculated that the increase in extracellular complexation favors the emergence of bisphosphonate-Ca 2 þ complexes, leading to changed drug pharmacokinetics at the cellular level and to a rapid enhancement of drug accumulation in tumor cells (Journé et al, 2008). On the other hand, Ca 2 þ has been reported to be major players in the propagation of necrotic cell death (Festjens et al, 2006;Kim et al, 2013).…”

Interactions of N-heteroalkylaminomethylenebisphosphonic acids with Cd(II) ions: Electrochemical and spectroscopic investigations

“…All of the ligands investigated in our work were studied previously as complexones of Zn(II) ions [14,15,20]. Zn and Cd lie in the same column in the periodic table, and thus it would be interesting to compare the stability constants of formed complexes.…”

“…Zn and Cd lie in the same column in the periodic table, and thus it would be interesting to compare the stability constants of formed complexes. By using the stability constants for Zn(II) complexes taken from the literature [14,15,20] and the obtained results for Cd(II) complexes, such a comparison was made and the hypothetical competition plots for each ligand were obtained ( Figure 6). The mixture of each ligand and both metal ions was fixed at Zn(II):Cd(II):L 1:1:2 molar ratio.…”