A thiophene based pyrrolo [1, 2-a] quinoxaline fluorescent probe as a “turn-off” sensor for the selective nanomolar detection of sodium ion

• Thiophene based pyrrolo [1, 2-a] quinoxalline sensor from thiophene 2-carboxaldehyde and 1-(2-amino phenyl) pyrrole. • Fluorescent detection of sodium ions by turn-off mechanism. • Sensor offers excellent selectivity towards sodium ions in competitive environment. • The proposed sensor offers nanomolar detection of sodium ions with a detection limit of 2.219 nM. • Effective fluorescent sensor for biological and environmental applications. • Computational studies were carried out to validate the experimental results. A novel thiophene based pyrrolo [1, 2-a] quinoxaline (TAAPP) fluorescent sensor, suitable for the nanomolar detection of sodium ions was successfully developed and characterized by various spectroscopic techniques. The fluorescent sensor showed excellent selectivity for sodium ions over other biologically and environmentally important metal ions/biomolecules by a remarkable quenching of fluorescence. Stern-Volmer studies reveal that static quenching predominates over dynamic quenching. The detection limit was found to be 2.219 nM within the linear range of 3 to 30 nM. DFT studies were performed to validate the results. The applicability of the probe can be extended to quantify sodium ions in real samples.