Thioxanthone-based organic probe with aggregation enhanced emission and exceptional mineral acids sensing abilities

The development of fluorescent probe(s) for naked eye analyte detection is an emerging area of research. Such probes can be judiciously engineered to realize analyte specific response with high sensitivity and broad applicability. Herein, we report reversible acid-base sensing ability of a donor-acceptor-donor (D-A-D) type thioxanthone-based luminophore 3,6-bis(dimethylamino)-9H-thioxanthen-9-one 10,10-dioxide (3). Photo-physical features of 3 in both the solid and solution states have also been determined. Moreover, the reported probe exhibited aggregation-enhanced emission (AEE) characteristics and pH dependent emission colour. An intramolecular charge transfer (ICT) process was observed between donor (N,N-dimethylamino) and acceptor (thioxanthone) units. The fact that changes can be seen under both the UV and visible lights without any special aid, signifies a remarkable prospect of this organic probe in distinguishing the commonly used laboratory acids of different strength.