Dual responsive salen-type Schiff bases for the effective detection of l-arginine via a static quenching mechanism

Abstract

L-Arginine is one of the most important amino acids and plays a key role in diagnostic studies. Herein, we report four salen-type Schiff base fluorimetric/colorimetric sensors for the rapid detection of L-arginine. Substituents play a major role in the sensing mechanism of probes with the nitro-substituent bearing probe showing the highest efficiency. A 1 : 2 complexation between all the probes and the analyte was evidenced from the absorption titrations; and the fluorescence studies revealed a quenching phenomenon occurring during complex formation. From the life time measurements, the nature of quenching was found to be static and the formation of a ground state complex was confirmed. DFT calculations done at the B3LYP/TZVP level of theory corroborated the experimental findings and further established the proton transfer from the probe to the analyte during the complex formation.