Inclusion complexes of nabumetone with β-cyclodextrins: thermodynamics and molecular modelling studies. Influence of sodium perchlorate

• Published in: Luminescence (Chichester, England) England), 2001-03, Vol.16 (2), p.117-127
• Main Authors: Goyenechea, Nerea, Sánchez, Miguel, Vélaz, Itziar, Martín, Carmen, Martínez-Ohárriz, Ma Cristina, González-Gaitano, Gustavo
• Format: Article
• Language: English
• Subjects: Anti-Inflammatory Agents, Non-Steroidal - chemistry; beta-Cyclodextrins; Butanones - chemistry; Cyclodextrins - chemistry; fluorescence; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; nabumetone; Perchlorates - chemistry; Sodium Compounds - chemistry; sodium perchlorate; Spectrometry, Fluorescence; Thermodynamics; β-cyclodextrin
• ISSN: 1522-7235; 1522-7243
• DOI: 10.1002/bio.615

Fluorescence, 1H‐NMR and molecular mechanics have been used to study the inclusion complexes of nabumetone (4,6‐methoxy‐2‐naphthyl‐butan‐2‐one; NAB) with β‐cyclodextrin (β‐CD), randomly methylated‐β (Mβ‐CD) and hydroxypropyl‐β‐cyclodextrins (HPβ‐CD). The emission spectrum of NAB shows a maximum whose fluorescence intensity increases with the different β‐CDs growing concentrations. This phenomenon allows calculation of the stability constants at 15, 25, 37 and 45°C. The thermodynamic parameters ΔH° and ΔS° for the inclusion process were obtained from the temperature dependence of the stability constants. Molecular mechanics calculations, together with proton NMR measurements, for the complex with β‐CD prove that the complex can be formed by penetration through any of the rims, with the naphthalene nucleus included and the substituents outside the cavity. The influence of NaClO4 in the aforementioned complexes has been analysed by spectrofluorimetric measurements. It has been found that the stability constants for the complexes decrease with the salt concentration; the causes are discussed. Copyright­© 2001 John Wiley & Sons, Ltd.