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Kinetic analysis of photoinduced reactions in hydrogen-bonded complexes of anthracene-urea with anions

Paper ID Volume ID Publish Year Pages File Format Full-Text
27856 44047 2012 5 PDF Available
Title
Kinetic analysis of photoinduced reactions in hydrogen-bonded complexes of anthracene-urea with anions
Abstract

Transient absorption measurement of urea-anthracene species nPUA (n = 1, 2, 9; PUA = 1-anthracen-n-yl-3-phenylurea) in the presence of acetate anions (tetrabutylammonium acetate, TBAAc) gave relatively long-lived transient species with lifetimes of ∼100 μs, which were unaffected by O2. The lifetimes showed significant temperature dependence, which allowed us to determine ΔH‡ and ΔS‡. ΔS‡ had a large negative value, in contrast to ΔH‡, indicating that the dissipation process of the transient species was entropy-controlled. A linear relationship between TΔS‡ and ΔH‡ suggested entropy–enthalpy compensation, which is generally found in host–guest systems with hydrogen bonding. These findings allowed us to assign the transient species as X, which is the ground state responsible for longer wavelength emissions, and conclude that the dissipation of the transient species corresponded to recovery of the complex in the ground state. We propose a reaction scheme for the photochemical process applying to urea derivatives in the presence of anions.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Transient species were observed for nPUA in the presence of an anion. ► The lifetimes of the transient species were ∼100 μs and were unaffected by O2. ► The lifetimes showed significant temperature dependence. ► The temperature dependence yielded the activation enthalpy and entropy. ► The results enabled us to propose a reaction scheme for the complex.

Keywords
Urea, Anthracene; Hydrogen bond; Transient spectroscopy; Thermodynamics
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Kinetic analysis of photoinduced reactions in hydrogen-bonded complexes of anthracene-urea with anions
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 250, 15 December 2012, Pages 1–5
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