Electrochemical and spectrophotometric determination of the formation constants of the ascorbic acid-β-cyclodextrin and dopamine-β-cyclodextrin inclusion complexes
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From UV–vis spectrophotometry and cyclic voltammetry it is demonstrated the interaction of dopamine, DA, and ascorbic acid, AA, with β-cyclodextrin, βCD, in aqueous media at pH 3.0. The formation constants of the respective inclusion complexes were also determined. The spectrophotometry data fed into the data processing software SQUAD, allowed calculation of the said constants for the AA–βCD complex (H2AA–βCD) giving a value of 3236 M−1, while for the dopamine complex DA–βCD (H3DA+βCD) this was 5888 M−1. From these results, the theoretical absorption spectra were generated which fitted quite well the experimental ones, thus indicating clearly that the constants are reliable. Moreover, from the cyclic voltammetry data, the stated constants were also calculated whereby that of the H2AA–βCD gave a value of 3981 M−1 while for the dopamine complex DA–βCD (H3DA+βCD) it was 4898 M−1. It is noteworthy to say that these values were similar to those found through spectrophotometry.
KeywordsDopamine Ascorbic acid β-cyclodextrin Inclusion complex UV–vis spectrophotometry Cyclic voltammetry
SCA 58250 and GAA 184930 express their gratitude to CONACyT for their postdoctoral and Ph.D., grants. MTRS thanks CONACyT for support through project 82932 and SCA for project 80305. Also GAA, SCA, MRR, MPP and MTRS gratefully thank the SNI for the distinction of their membership and the stipend received. MPP and MRR wish to thank the Departamento de Materiales, UAM-A, for the financial support given through projects (2261203, 2261204, 2261205).
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