The synthesis of a series of fluorescent emitters and their application for dye lasing and cation sensing

The following paper reported four carbazole-modified fluorescent emitters. Their molecular structure and elec-tronic transition were analyzed via their single crystal and theoretical calculation. Their photophysical parameters, including absorption, emission and quantum yield, were determined and discussed. It was found that the emission performance of benzo-thiazole-based dyes was better than that of benzo-imidazole-based dyes, owing to the electron-donating effect from the S atom. Upon the presence of metal cations, these photophysical parameters were re-measured. Benzo-thiazole-based dyes were found insensitive towards most metal cations, while benzo-imidazole-based dyes showed obvious photophysical variation upon these metal cations, including absorption red shift and emission quenching. Detailed sensing performance of a representative dye was discussed. A linear working curve with good selectivity was finally observed. Its sensing mechanism was confirmed as the coordination between metal cation and deprotonated benzo-imidazole group. Benzo-thiazolebased dyes showed amplified spontaneous emission (ASE) behavior, with threshold energy of-220 mu J. Given the optimal condition, a highest ASE efficiency of -2% was observed, with FWHM value of 6 nm and emission peak of 435 nm. The major novelty and advancement of these fluorescent dyes shall be the stable ASE output (dye 4) under UV excitation and the linear sensing curve with good selectivity (dye 3), which was a hard task for emission turn off sensing probes. We attributed its causation to the valent-recognizing sensing mechanism. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study investigated four carbazole-modified fluorescent emitters, highlighting the superior emission performance of benzo-thiazole-based dyes under the presence of metal cations. A fluorescent dye with a linear working curve and good selectivity was studied.