Speciation studies of Co(II), Ni(II) and Cu(II) complexes of L-valine in acetonitrile–water mixtures

Abstract

Chemical speciation of binary complexes of Co(II), Ni(II) and Cu(II) with L-valine in 0.0-60.0% v/v acetonitrile-water mixtures was studied pH-metrically at an ionic strength of 0.16 mol L -1 at 303.0 K. The existence of different binary complexes was established from the modelling studies, using the computer program MINIQUAD75. The appropriateness of the model was ascertained by studying the effect of errors in concentrations of the reagents. The trend in variation of stability constants with change in the permittivity of the medium is explained on the basis of electrostatic and non-electrostatic forces. The species distribution diagrams and the plausible equilibria for the formation of the species are also presented.

Speciation Study of L-ascorbic Acid and its Chelated Cu(II) & Ni(II) Complexes: an Experimental and Theoretical Model of Complex Formation

“…Different percentage of species of both metal complexes 20 with variation of pH were calculated using SIM software and shown in (Tables 3 and 4). The species distribution diagram of metal ions Ni(II) and Cu(II) form different species 21,22 with L-ascorbic acid are shown in ( The species distribution diagrams of binary systems were plotted pH versus % of different species formed at a particular pH and were performed using software SIM and Origin-8. These equilibria for the formation different species of ascorbic acid and their different complex formation in aqueous in the studied pH ranges can be represented as follows:…”

Mononuclear Binary Complex Formation Equilibria of L-Ornithine with Biologically Essential Metals in TBAB Micellar Media

“…L-Ornithine (L-Orn) is a non-protein 2,5-diaminopentanoic acid whose metal complexes are insoluble in water and soluble in most organic solvents [9]. It is a tridentate ligand [10,11] and known to form several stable metal ion complexes in a variety of solvents differing in the degree of solubility: with Co(II), Ni(II) and Cu(II) [12][13][14][15][16][17][18][19][20][21][22]; Cd(II), Sn(IV), Ce(IV) and Pd(II) in different solvents [23][24][25][26][27]. L-Ornithine complexes of bio-essential metals play an important role in chemotherapeutic applications [28,29].…”

Metal complexes of amino acids and peptides

“…Only the side-chain imidazole was found to coordinate under neutral condition. 119 In the same laboratory, solution equilibrium study was performed on Co(II), Ni(II) and Cu(II) complexes of L-Val in acetonitrile-water, 120 in propylene glycolwater 121 solvent mixtures. 112 In addition to the above cited papers on synthesis and characterization of half-sandwich ruthenium complexes, solution equilibrium study on the interaction between [Ru(Z 6p-cym)(H 2 O) 3 ] 2þ and Ser or Ise has been performed by pH-potentiometry, 1 H NMR and ESI-MS techniques.…”