Supramolecular Interaction of Coumarin 1 Dye with Cucurbit[7]uril as Host: Combined Experimental and Theoretical Study

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• 作者：Monika Gupta ; Dilip K. Maity ; Manoj K. Singh ; Sandip K. Nayak ; Alok K. Ray
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：May 10, 2012
• 年：2012
• 卷：116
• 期：18
• 页码：5551-5558
• 全文大小：376K
• 年卷期：v.116,no.18(May 10, 2012)
• ISSN：1520-5207

文摘

Molecules of the coumarin family have fluorescence characteristics that are highly sensitive to their environment, and thus, they have been used as fluorescent sensors in chemical and biological systems. However, the very poor fluorescence yield of most coumarin dyes in aqueous media limits their applications. We have adopted a supramolecular strategy to improve the fluorescence intensity of coumarin dye through its interaction with the relatively new host cucurbit[7]uril (CB[7]). The virtually nonfluorescent coumarin 1 (桅_f = 0.04) was converted into a highly fluorescent (桅_f = 0.52) entity in water upon addition of the nonfluorescent host CB[7]. Various spectroscopy techniques, namely, UV鈥搗is absorption and steady-state and time-resolved fluorescence spectroscopies, established the formation of a strong 1:1 dye鈥揅B[7] inclusion complex with a high binding constant of (1.2 卤 0.1) 脳 10⁵ M^鈥? for the dye. The stable inclusion complex of the neutral molecule was supported by density-functional-theory- (DFT-) based quantum chemical calculations. Energy decomposition analysis of various interaction factors in the host鈥揼uest complex revealed that key components providing stability to the complex were electrostatic, polarization, and charge-transfer energies. These new results on the formation of a strong inclusion complex of the versatile fluorophore coumarin 1 with the nontoxic host CB[7] could lead to the design of efficient molecular-scale biological probes, sensors, and photostable aqueous UV dye lasers.