NOVEL SYNTHESIS OF 3,3´-DIHYDROXYFLAVONE AND APPARENT FORMATION CONSTANTS OF FLAVONOID–Ga(III) COMPLEXES

FERRARI G. V.; PAPPANO N. B.; MONTAÑA M. P.; GARCÍA N. A.; DEBATTISTA N. B.

JOURNAL OF CHEMICAL AND ENGINEERING DATA

AMER CHEMICAL SOC

Lugar: Indiana; Año: 2010 vol. 55 p. 3080 - 3083

0021-9568

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.