title: Effect of cyclodextrins on the physicochemical properties of chlorophyll a in aqueous solution.
abstract: The interactions between chlorophyll a and two beta-cyclodextrins, that have the same cavity size but different substituents, were studied in aqueous solutions. These supramolecular host-guest complexes were examined by a combination of UV/vis absorption, circular dichroism, NMR, and steady-state and time-resolved fluorescence measurements. The results indicate that all cyclodextrins solubilize the pigment mainly in monomeric form in water. The pigment forms 1:1 complexes with the heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin and 1:2 complexes with the hydroxypropyl-beta-cyclodextrin. In such complexes the methyl groups of the cyclodextrin inner cavity are involved in the interaction with the pigment as evidenced by NMR measurements. We also measured the luminescence of singlet oxygen photosensitized by chlorophyll a in the inclusion complexes.
authors.affiliation: Dipartimento di Chimica, Università di Bari, Via Orabona 4, 70126 Bari, Italy.
authors.forename: Pasquale L
authors.initials: PL
authors.lastname: Dentuto
authors.forename: Lucia
authors.initials: L
authors.lastname: Catucci
authors.forename: Pinalysa
authors.initials: P
authors.lastname: Cosma
authors.forename: Paola
authors.initials: P
authors.lastname: Fini
authors.forename: Angela
authors.initials: A
authors.lastname: Agostiano
authors.forename: Lucia
authors.initials: L
authors.lastname: D'Accolti
authors.forename: Colleen C
authors.initials: CC
authors.lastname: Trevithick-Sutton
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Foote
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002734:Chlorophyll / Q000737:chemistry*; D000077194:Chlorophyll A; D002942:Circular Dichroism; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013997:Time Factors; D014867:Water / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D012996:Solutions; D047392:beta-Cyclodextrins; D014867:Water; D002734:Chlorophyll; D010100:Oxygen; D000077194:Chlorophyll A