title: Determination of absorptivity and formation constant of a chalcone association complex.
abstract: A UV spectrometric method was developed to determine the molar absorptivity (epsilon(C)) and formation constant (K(c)) of the association complex of unsubstituted chalcone in cyclohexane, in the concentration range from 4.00.10(-4) to 2.00.10(-2) mol dm(-3). The thermodynamic and spectroscopic magnitudes such as K(c) and epsilon(C) contribute to the understanding of the physicochemical behavior of several alpha,beta-unsaturated carbonylic compounds, of low solubility in water, as it is the case of numerous flavonoids of chemical and biological importance. The studied association complex, formed by two chalcone molecules, is characterized by the constants epsilon(C) (300.8 nm)=4.98.10(4) dm(3) mol(-1) cm(-1) and K(c)=5.58.10(3). The method proposed is convenient for the study of solute-solute molecular associations particularly those due to dipole-dipole interactions.
authors.affiliation: Departamento de Quimica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina.
authors.forename: S E
authors.initials: SE
authors.lastname: Blanco
authors.forename: F H
authors.initials: FH
authors.lastname: Ferretti