Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotryptophan emits in the visible region and is the smallest blue fluorescent amino acid probe for biological applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole-4-carboxylate emits at 450 nm with a long fluorescence lifetime, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing ester-derivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.
Ester-Derivatized indoles as fluorescent and infrared probes for hydration environments†
Xin-yue Huang, Min You, Guang-liu Ran, Hao-ran Fan, Wen-kai Zhang; Ester-Derivatized indoles as fluorescent and infrared probes for hydration environments. Chin. J. Chem. Phys. 1 August 2018; 31 (4): 477–484. https://doi.org/10.1063/1674-0068/31/cjcp1805118
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