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Photoprocesses of alkyl meso-thiacarbocyanine dyes in the presence of cucurbit[7]uril

Paper ID Volume ID Publish Year Pages File Format Full-Text
25863 43894 2015 9 PDF Available
Title
Photoprocesses of alkyl meso-thiacarbocyanine dyes in the presence of cucurbit[7]uril
Abstract

•Alkyl meso-thiacarbocyanines form fluorescent complexes with CB(7) in solution.•The dimeric inclusion complexes exhibit delayed fluorescence in ms time scale.•The presence of monovalent metal cation is prerequisite for delayed fluorescence.•Dimeric structure of complexes was confirmed by PM3 calculations.

The effects of cucurbit[7]uril, CB7, on the photophysical processes of 3,3′-diethyl-9-methylthiacarbocyanine iodide (1), 3,3′-dihydroxyethyl-9-methylthiacarbocyanine chloride (2) and 3,3′-diethyl-5,5′-dichloro-9-ethylthiacarbocyanine p-toluene sulfonate (3) were studied in phosphate buffer (pH 6.86) mostly at room temperature. Dyes 1–3 are cationic and present as equilibrated mixtures of monomers and dimers. Without CB7 the monomers demonstrate low yield of fluorescence which is increased 7–15 fold in the presence of CB7 as a result of formation of monomeric inclusion complexes. The dimers practically do not fluoresce. In the presence of CB7 the dimers produce dimeric inclusion complexes which exhibit both prompt and delayed fluorescence. The portion of delayed fluorescence is 0.08–0.1 of the total emission and the lifetimes are 0.07, 0.1, 0.25 ms for 1, 2 and 3 respectively. The presence of monovalent metal ions or ammonium cation in aqueous solution of the dyes is prerequisite for delayed fluorescence of dimeric inclusion complexes. On the basis of quantum-chemical calculations the proposed structure of dimeric inclusion complex is characterized by near parallel orientation of two π-stacking chromophores retaining planar configuration, whereby each of them is partly inserted into the CB7 inner cavity. The difference in counter ions (chloride and p-toluene sulfonate) is reflected in the structure of dimeric inclusion complexes.

Graphical abstract•Up to 7–15-fold enhancement of prompt fluorescence of monomeric inclusion complex.•Formation of dimeric inclusion complex.•Delayed fluorescence of dimeric inclusion complex.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Cyanine dyes; Cucurbiturils; Monomeric inclusion complexes; Dimeric inclusion complexes; Absorption; Delayed fluorescence; Quantum chemical calculations
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Photoprocesses of alkyl meso-thiacarbocyanine dyes in the presence of cucurbit[7]uril
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 302, 1 April 2015, Pages 69–77
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
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