Photochemistry of “Super”-Photoacids. Solvent Effects
Photochemistry of “Super”-Photoacids. Solvent Effects
复制标题
“超级”光酸的光化学。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Noam Agmon
中科院分区：
文献类型：
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作者：
Kyril M. Solntsev† and;D. Huppert;Noam Agmon
We study steady-state and time-resolved fluorescence of 5-cyano-2-naphthol in various pure solvents. To some of these, excited-state proton transfer occurs within the excited-state lifetime of the chromophore. Solvatochromic shifts in the acid and anion bands are analyzed using the empirical Kamlet−Taft approach. The hydrogen-bond donated from the OH group to basic solvents accounts for most of the shift in the excitation spectra. This bond produces considerably larger shifts in the emission spectra, suggesting that it strengthens in the excited state. In contrast, the hydrogen bond donated from protic solvents to the hydroxyl oxygen is cleaved following photoexcitation. This bond (and not the change in dielectric constant) is responsible for the solvent-induced blue shift in anion fluorescence. Hence it must re-form simultaneously with the proton-transfer event. Our time-resolved fluorescence data fit the solution of the Debye−Smoluchowski equation for reversible geminate recombination in a field of forc...
