Determination of absorptivity and formation constant of a chalcone association complex

• Published in: Talanta (Oxford) Vol. 45; no. 6; pp. 1103 - 1109
• Main Authors: Blanco, Sonia E., Ferretti, Ferdinando H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.1998; Oxford Elsevier
• Subjects: Absorptivity constant; Chemistry; Exact sciences and technology; Formation constant; General and physical chemistry; Solution properties; Solutions; UV spectrometric method; Formation constant; Absorptivity constant; UV spectrometric method; Absorption spectroscopy; Ultraviolet spectroscopy; Cyclohexane; Benzenic compound; Enone; Chalcone; Physicochemical properties
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/S0039-9140(97)00209-9

A UV spectrometric method was developed to determine the molar absorptivity ( ε 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 ε C contribute to the understanding of the physicochemical behavior of several α, β-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 ε 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.