Complexing of biometal cations (Ca2+, Mn2+) with ethylenediamine-N,N '-bis(methylenephosphonic) acid

The complexing of biometals (Ca2+, Mn2+) with ethylenediamine-N,N'-bis(meth ylenephosphonic) acid (EDMP) was studied by the mathematical simulation of experimental potentiometric titration data from the M2+-EDMP-H2O system (M2 + = Ca2+, Mn2+). The most stable complexes of the studied biometal cations with EDMP were identified using the AUTOEQUIL program. Their formation cons tants were calculated. The distribution diagrams of the equilibrium concent rations of the complexes depending on the solution I,II and computer databa ses for complex species in the form of the Microsoft Access 97 relation dat abase management system are presented. The previously discovered coordinati on abilities of EDMP were verified: the formation of bis-complexes M(HiL)(2 ) (i = 1, 3) and binuclear M2L or M2HL complexes in addition to the MH,L (i = 1, 2, 3, 4) species. The utility of EDMP for medicine is due to its abil ity to form several complex species at pH similar to 7.4. These species wer e derived from the computer database for different concentration ratios of the metal to ligand.