Highly-selective recognition of dicarboxylic acid using 9-(diphenylmethylene)fluorene-based diamidine

A 9-(diphenylmethylene)fluorene-based diamidine 1 has been designed and synthesized for the detection of dicarboxylic acids as a turn-on fluorescence sensor. The obtained diamidine 1 itself does not show any fluorescence, but a blue fluorescence was observed after the addition of pimelic acid 3e (n = 5) with a high selectivity (does not show a remarkable fluorescence with the addition of other carboxylic acids) in a DMSO/MeCN/H2O mixed solvent, and also succeeded in the detection of an aqueous solution of pimelic acid 3e. Therefore, higher methylene chain length selectivity toward a,omega-dicarboxylic acids 3 was observed for the 9-(diphenylmethylene)fluorene-based diamidine 1 (detection of only 3e) compared to the tetraphenylethylene (TPE)-based diamidine 1' (detection of 3c-3h). (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

A fluorescence turn-on sensor based on a 9-(diphenylmethylene)fluorene-based diamidine has been designed and synthesized for the detection of dicarboxylic acids. The sensor showed high selectivity and successfully detected the aqueous solution of the target dicarboxylic acid.