fulltext.study @t Gmail

Comparative effect of cyclodextrin nanocavities versus organic solvents on the fluorescence of carbamate and indole compounds

Paper ID Volume ID Publish Year Pages File Format Full-Text
27481 44026 2008 7 PDF Available
Title
Comparative effect of cyclodextrin nanocavities versus organic solvents on the fluorescence of carbamate and indole compounds
Abstract

The effect of the addition of different amounts of organic solvents (S) on the fluorescence of aromatic compounds (C) and their inclusion complexes with β-cyclodextrin (βCD) and hydroxypropyl-β-cyclodextrin (HPCD) has been examined using steady-state measurements. Carbamate pesticides with different aromatic moiety, such as carbofuran (CF), promecarb (PC), carbaryl (CY) and bendiocarb (BC) were used, as well as indole derivatives with different polarity in their lateral chains, such as melatonin (M, neutral), 5-methoxytryptamine (MT, cation) and auxin (IA, anion). Their complexes in water show a fluorescence signal higher than that obtained for the free substrates in solvent:water mixtures (30%, v/v n-propanol or acetonitrile, and 50%, v/v methanol). The isofluorescent point (IF), the %IF and the F85% are defined in order to evaluate the use of CD nanocavities as a non-polluting alternative for the analysis of the compounds analyzed.Apparent formation constants (KAP, M−1) for the complexes of C:HPCD at different solvent percentages were determined for CF and PC with methanol (MeOH), n-propanol (ProOH) and acetonitrile (ACN), and for indole compounds with ACN. A decrease in the KAP values for the CF:HPCD (120–30) and PC:HPCD (2000–400) complexes occurs in accordance with the solvent affinities for CDs (MeOH < ACN < ProOH). Nevertheless, in the indolic series, the polar characteristics of MT, IA and M determine their behaviour in the presence of ACN. For the neutral substrate M, KAP decreases with the increasing percentage of ACN (100–10). In contrast, for IA and MT (ionic substrates) KAP increases (10–100).These results may be accounted for by two different mechanisms: the competition between C and S for the cavity of the receptor or the formation of ternary complexes C:S:CD with additional stabilization.

Keywords
Isofluorescence point; Solvent replacement; Ternary complex; Solvent competition; Cyclodextrin nanocavity
First Page Preview
Comparative effect of cyclodextrin nanocavities versus organic solvents on the fluorescence of carbamate and indole compounds
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 198, Issues 2–3, 15 August 2008, Pages 179–185
Authors
, , ,
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