Novel Synthesis of 3,3′-Dihydroxyflavone and Apparent Formation Constants of Flavonoid−Ga(III) Complexes

• Published in: Journal of chemical and engineering data Vol. 55; no. 9; pp. 3080 - 3083
• Main Authors: Ferrari, Gabriela V, Pappano, Nora B, Montaña, M. Paulina, García, Norman A, Debattista, Nora B
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.09.2010
• Subjects: Chemistry; Coordination compounds; Exact sciences and technology; Inorganic chemistry and origins of life; Preparations and properties; Organic ligand; Apparent quantity; Stability constant; Gallium III Complexes; Trivalent metal Complexes; Chemical synthesis; Flavonoid
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je901091f

Flavonoids are a wide variety of polyphenolic compounds. They have many biological properties. They also exhibit a metallic ion complexation capacity, which is important since it has been found that biological properties these ligands present can be enhanced when complexation occurs. In this work four flavonoid−Ga(III) complexes were studied: 2′,4′,3-trihydroxychalcone−Ga(III), 2′,3-dihydroxychalcone−Ga(III), 3,7,3′-trihydroxyflavone−Ga(III), and 3,3′-dihydroxyflavone−Ga(III). All ligands were synthesized by our working group, contributing a novel, cheaper, and more simple way to obtain 3,3′-dihydroxyflavone. The stoichiometry of the complexes was determined using the Yoe−Jones method. Both chalcone−Ga(III) complexes presented 1:1 L:M stoichiometry; meanwhile flavone−Ga(III) complexes presented 2:1 L:M stoichiometry. The pK values were determined by means of a spectrophotometric method. Values obtained were: 2′,4′,3-trihydroxychalcone−Ga(III), pK = 4.35 ± 0.38; 2′,3-dihydroxychalcone−Ga(III), pK = 3.40 ± 0.17; 3,7,3′-trihydroxyflavone−Ga(III), pK = 7.74 ± 0.19; and 3,3′-dihydroxyflavone−Ga(III), pK = 8.46 ± 0.27.