Degradation of supramolecular complexes photoinduced by iron(III): the influence of the host on the reactivity of the guest

• Published in: Photochemical & photobiological sciences Vol. 2; no. 2; pp. 163 - 170
• Main Authors: Hykrdová, Lenka, Jirkovský, Jaromír, Grabner, Gottfried, Mailhot, Gilles, Bolte, Michèle
• Format: Journal Article
• Language: English
• Published: England 01.02.2003
• Subjects: Aniline Compounds - chemistry; Ferric Compounds - chemistry; Hydroxyl Radical - chemistry; Kinetics; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Conformation; Naphthalenes - chemistry; Phenols - chemistry; Photolysis; Spectrophotometry, Ultraviolet; Thermodynamics; Water - chemistry; Water Pollutants, Chemical
• ISSN: 1474-905X; 1474-9092
• DOI: 10.1039/b204376a

Fe(III)-photoinduced degradation of two different supramolecular host-guest complexes, naphthalene with alpha-cyclodextrin and 4-chloroaniline with p-sulfonic-calix[4]arene; was studied in aqueous solution. The stoichiometries, equilibrium constants and conformations of these complexes were characterized. In both cases, the degradation of the guest could not be accounted for by simple competition kinetics of OH radical attack on the guest and host molecules, respectively. This observation was explained by the occurrence of subsequent radical reactions of transients resulting from an OH attack onto the host molecule, which are assumed to be able to induce additional degradation reactions of the guest. An inhibiting influence of the calix[4]arene host on the abundance of oligomeric degradation intermediates of 4-chloroaniline was observed.