酸性介质罗丹明衍生物荧光染料的合成

wo novel rhodamine derivatives (A2 and A3) have been designed and synthesized. The introduction of different N-containing groups assigns the two derivatives with different pKa values (5.4 for A2 and 6.0 for A3), which makes them different than common rhodanmine derivatives, i.e., A2 and A3 are more suitable for acid environment. A2 and A3 were characterized by 13C-NMR, 1H-NMR and HRMS (high resolution mass spectrometry). Fluorescence response to pH and spectral properties were investigated in H2O. Fluorescence maximum of A2 is 538 nm and that of A3 564 nm, and they both display red shifts (7 nm for A2 and 26 nm for A3) for absorption maximums towards the addition of H+. Moreover, they both remain a high fluorescence quantum yield in H2O within different pH with the maximum values of 0.88 (A2 at pH 3.9) and 0.67 (A3 at pH 4.4).