Complexation of Ni(ClO sub(4)) sub(2) and Mg(ClO sub(4)) sub(2) with 3-Hydroxyflavone in Acetonitrile Medium: Conductometric, Spectroscopic, and Quantum Chemical Investigation

• Published in: The journal of physical chemistry. B 2014-01, Vol.118 (42), p.12251-12262
• Main Authors: Agieienko, Vira N, Kalugin, Oleg N
• Format: Article
• Language: English
• Subjects: Acetonitrile; Anions; Carbonyl groups; Cations; Complexation; Flavonols; Mathematical analysis; Solvation
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp5080829

The complex formation of Ni(ClO sub(4)) sub(2) and Mg(ClO sub(4)) sub(2) with 3-hydroxyflavone (HL, flavonol) in acetonitrile was studied using conductometric and spectroscopic methods. It was found that interaction of nickel cation with HL leads to formation of the doubly charged [Ni(HL)] super(2+) complex, whereas in solutions of magnesium perchlorate the complex with anion [MgClO sub(4)(HL)] super(+) is formed. Using the extended Lee-Wheaton equation, the limiting equivalent conductivities of [Ni(HL)] super(2+) and [MgClO sub(4)(HL)] super(+) and thermodynamic constants of their formation were obtained at 288, 298, 308, 318, and 328 K. Calculated Stoke's radii indicate weak solvation of the formed complexes and low temperature stability of their solvation shells. On the basis of the quantum chemical calculations and noncovalent interactions analysis, it is found that in the solvated [Ni(HL)] super(2+) and [MgClO sub(4)(HL)] super(+) complexes interaction of the Ni super(2+) and Mg super(2+) cations with flavonol occurs via the carbonyl group of HL. Complexation with Ni super(2+) does not change the internal structure of HL greatly: in the [Ni(HL)] super(2+) complex, flavonol shows an intramolecular H-bond between 3-hydroxyl and carbonyl groups. When a complex with [MgClO sub(4)] super(+) is formed, the OH group turns out of the plane of the chromone moiety that leads to rupture of an intramolecular H-bond in the ligand molecule. Moreover, in the [MgClO sub(4)(HL)] super(+) complex, perchlorate anion possesses a strong ability to interact with HL, forming an intracomplex H-bond between hydrogen of the 3-hydroxyl group and oxygen of ClO sub(4) super(-). Its strength is more pronounced than in the intramolecular one in both [Ni(HL)] super(2+) and uncomplexed 3-hydroxyflavone.