Three coumarin based fluorescent dyes as shown in Fig. 1 were produced by a microwave-assisted one-pot procedure according to our previous studies [17]. The purity of the produced dyes (more than 90%) was monitored by TLC. All the dyes 1 (a–c) were excited at 435–436 nm and showed green fluorescence emission with high intensity (λmax at 490–500 nm)..