Synthesis of rare earth ternary complexes using tryptophan and sodium citrate and their anticoagulant action

Using rare earth nitrates, tryptophan (L), and sodium citrate (NaL′), three new rare earth ternary complexes (Nd-L-L′· 4H2O, Eu-L-L′ · 4H2O, and La-L-L′ · 4H2O) were prepared. The complexes were characterized by IR, molar conductivity, TG-DTA (thermo gravimetric-differential thermal analysis), 1H NMR, and elemental analyses. TG and elemental analyses of the prepared complexes showed good agreement with their stoichiometry. Compared with two individual ligands, IR spectra of synthesized complexes showed dramatic shift and intensity changes; 1H NMR also showed a slight downfield shift. All analytical results of complexes proved constant composition of M-L-L′ · 4H2O (M = rare earth metal, namely Nd, Eu, or La). Animal tests were also performed to study the anti-coagulation time of these complexes considering also the different concentration of complex Nd-L-L′ · 4H2O. PC-12 pheochromocytoma cells were used to study cell adhesion. Compared with ions of rare earth compounds, rare earth ternary complexes have lower cell toxicity, better cell adhesion, and better anticoagulant action.