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Fluorescence properties of (R)- and (S)-[1,1′-binaphthalene]-2,2′-diols solutions and their complexes with cyclodextrins in aqueous medium

Paper ID Volume ID Publish Year Pages File Format Full-Text
28978 44112 2008 12 PDF Available
Title
Fluorescence properties of (R)- and (S)-[1,1′-binaphthalene]-2,2′-diols solutions and their complexes with cyclodextrins in aqueous medium
Abstract

Steady-state and time-resolved fluorescence techniques were used to study (R)- and (S)-[1,1′-binaphthalene]-2,2′-diol (1,1′-binaphthol or BINOL) dilute solutions of different polarity solvents, as well as their inclusion complexes with α- and βcyclodextrins (CDs) in water. BINOLs in dilute water solutions exhibited a surprisingly high fluorescence anisotropy that was explained as being due to the formation of fairly large order π–π stacking aggregates in aqueous polar media. Stoichiometries, formation constants and the changes of enthalpy and entropy upon inclusion were also obtained by measuring the variation of the fluorescence intensity with [CD] and temperature. Results agree with the formation of 1:1 stoichiometry complexes, but the association constants are rather low and very similar for both enantiomers. Molecular mechanic calculations in the presence of water were employed to study the formation of BINOL complexes with both α- and βCDs. For the most stable structures of any of the complexes only a small portion of the guests, in agreement with thermodynamics parameters and quenching experiments, penetrates inside the CD cavities. Driving forces for 1:1 inclusion processes may be dominated by non-bonded van der Waals host:guest interactions. The low guest:host binding constants and poor enantioselectivity of α- and βCDs for BINOLS may be a consequence of the BINOL aggregation in water.

Keywords
Cyclodextrins; Inclusion complex; Fluorescence; Molecular mechanics; [1,1′-Binaphthalene]-2,2′-diol (1,1′-binaphthol or BINOL)
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Fluorescence properties of (R)- and (S)-[1,1′-binaphthalene]-2,2′-diols solutions and their complexes with cyclodextrins in aqueous medium
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 200, Issues 2–3, 15 December 2008, Pages 114–125
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us