Abstract
Cyclodextrins are known by their properties of molecular recognition. In the present work, it was established, by using high-performance liquid chromatography, that complexes between 2-hydroxypropyl-β-cyclodextrin (HPCD) and d- and l-tryptophan are readily formed in solution. Association constants of (2 ± 1) × 10 and of (9 ± 2) × 10− 1 for d and l-isomers, respectively, were calculated from UV electronic spectroscopy experiments. Solid state complexes were characterized by Fourier-transform infrared spectroscopy, which showed that the subtracted/deconvoluted spectra present wavenumber changes of the NH3 + asymmetric angular deformation and of the COO− asymmetric stretching.
Acknowledgements
We are grateful to CAPES, CNPq and FAPERJ for financial support. We would like also to thank Prof. Carlos Alberto Lombardi Filgueiras for the kind revision of the manuscript.