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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 34, Number 5
BKCSDE 34(5)
May 20, 2013 

 
Title
Fluorescence Enhancement of 7-Diethylamino-4-methylcoumarin by Noncovalent Dipolar Interactions with Cucurbiturils
Author
Mee Ock Park, Myung Gu Moon, T. J. Kang*
Keywords
Cucurbiturils, Complex, Fluorescence, n-Diethylamino-4-methylcoumarin
Abstract
We have investigated the complex forming behavior of cucurbit[6]urils(CB6) and cucurbit[7]urils(CB7) with 7-diethylamino-4-methylcoumarin(C460) in water. The electronic absorption maximum of C460 shows bathochromic shift with the addition of CB7 and fluorescence intensity is greatly increased, while CB6 has no noticeable effects on the spectroscopic properties of C460. It is noted that CB7 interacts more strongly with C460 than CB6 does. Fluorescence lifetime also significantly increased for the CB7 complex, which is attributed to reduced polarity surrounding C460 and/or C460 being in a restricted environment. The stoichiometry for the complex formation determined from the fluorescence titration measurement indicates that 2:1 complex in which two CB7 molecules bind to C460 is formed. Thus, two step equilibrium processes are suggested for the complex formation and the binding constants are estimated. The semi-empirical electronic structures calculations indicate that C460 is not included in the CB7 cavity but interacts noncovalently with the portal carbonyls of CB7.
Page
1378 - 1382
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