Development of firefly oxyluciferin derivatives as pH sensitive fluorescent Probes: A DFT/TDDFT study

Publication date: 1 June 2018 Source:Computational and Theoretical Chemistry, Volume 1133 Author(s): Chun-Gang Min, Qing-Bo Liu, Yan Leng, Shao-Jun Huang, Chun-Xia Liu, Xi-Kun Yang, Ai-Min Ren, Luís Pinto da Silva Because of its high fluorescence quantum yield, high sensitivity and high signal-to-noise ratio, firefly oxyluciferin is widely used in the field of fluorescent probe. However, there are six chemical forms which can possibly co-existence in solution. Reliable relative stability of the different forms in solution made the analysis of their photophysical properties difficult. In order to address this issue and gain insights into the nature of spectra feature observed in the experiments, we designed six oxyluciferin derivatives. The distribution of the species at the ground and excited states demonstrate that only keto(0), keto(−1) and enol(−2) are present for all oxyluciferin derivatives. The majority of molecules are surprisingly more acidic at the ground state than at the excited state, which indicate that they are photobases. The distribution of the species at the excited state indicate that the most pH-sensitive molecules are 2-(6′-hydroxybenzothiazol-2-yl)-2,3-dihydro-4-hydroxypyrrole (Oxyan-1) and 1-(5′-brominated-6′-hydroxybenzothiazol-2-yl)-2-(4-hydroxythiazole) ethylene (Oxyan-4), as their chemical equilibria consist on the same three species: keto(0), keto(−1) and enol(−2). While the first deprotonation occurs at acidic pH, the secon...

Source: Computational and Theoretical Chemistry - May 3, 2018 Category: Chemistry Source Type: research