Equilibria of Complex Formation between Bivalent Metal Ions and 3,3′-Bis[N,N′-bis(carboxymethyl)aminomethyl]-o-cresolsulfonphthalein

Abstract

The complex formation equilibria between several bivalent metal ions and 3,3′-bis[N,N′-bis(carboxymethyl)aminomethyl]-o-cresolsulfonphthalein (XO) have been investigated potentiometrically and spectrophotometrically. The metal ions studied here were Co(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II). The formation constants and visible-absorption-spectrum parameters of these metal complexes have been determined. It has been found that all these metal ions form 1:1 and 2:1 (metal: XO) complexes with XO. Moreover, the complex of each composition changes into one of several protonated ones depending on the pH of the solution. The probale structures of the complexes in solution are discussed.

Equilibria of Complex Formation between Bivalent Metal Ions and 3,3‘-Dimethyl-5,5‘-bis[(N,N-bis(carboxymethyl)amino)methyl]- phenolphthalein

“…where K 7 and K 10 are the equilibrium constants for equilibria ( 7) and ( 10), respectively, and K a 1 , K a 2 , K a 3 , K a 4 , K a 5 , and K a 6 are proton dissociation constants for OCP. The formation curves (Figure 1) indicate that OCP forms 1:1 as well as 2:1 metal-ligand stoichiometry with these bivalent metal ions, which is in good agreement with earlier reports of Sarkar et al (1967), Gaizer et al (1981) for alkaline earth ions, and Murakami et al (1980) for xylenol orange with divalent metal ions. Moreover Table 1 indicates that no significant change (except in the case of Pb 2+ and Cu 2+ ) in equilibrium constant values has been observed when it was evaluated by (i) taking into account and (ii) ignoring the simultaneous formation of hydroxo species of the metal ion in the solution.…”

Preparation and characterization of green adsorbent on functionalized and nonfunctionalized ALOE VERA: A combined experimental and DFT calculations

“…The supernatant of the samples was centrifuged and analyzed by Double beam UV-VIS OPTEZEN 3220 for absorbance measurements at max = 585 nm, λ max = 575 nm of Pb (II), and Cd (II) respectively with orange xylenol (colored indicators) to buffer 5.8 [28].…”

Indicator approach to develop a chemosensor for the colorimetric sensing of thiol-containing water and its application for the thiol detection in plasma

“…The new system is prepared by mixing CuCl 2 and xylenol orange (abbreviated as XO, usually used as a metal indicator) [55][56][57] in a 1 : 1 molar ratio in an aqueous solution of HEPES buffer (10 mM, pH 6.0). Fig.…”