A Dual Sensor Probe for the Sequential Detection of Copper(II) and Lactic Acid

Herein, we report a novel fluorescent probe for the sequential detection of Copper II (Cu²⁺) and lactic acid. The probe based on acyl-thiourea derivative, N-((6-methoxypyridin-2-yl)carbamothioyl)benzamide (1) was synthesized, and its application as dual sensor for Cu²⁺ and lactic acid is reported. The dual detection by the probe is possible since 1 formed complex with Cu²⁺ and yielded yellow solution which disappeared after the addition of lactic acid. The probe exhibits yellow fluorescence with Cu²⁺ and LOD of Cu²⁺ with fluorescence is as low as 0.1ppm. The fluorescence is quenched after the addition of lactic acid and LOD of fluorescence quenching by lactate is as low as 1 ppm. Further, structural modification in the probe 1 suggest crucial role of both pyridine and acyl-thiourea moiety in the binding of Cu²⁺. Interestingly, 1 also assembles to fluorescent fibers which show tunable emission properties. These fibers are broken in the presence of Cu²⁺ and regenerated in the presence of lactic acid. Hence, disaggregation at molecular level might play a crucial role in causing yellow fluorescence in the presence of Cu²⁺. To, the best of our knowledge, this is the first report wherein a dual sensor for Cu²⁺ and lactate ion is synthesized and it may in all possibilities pave the way for diagnosis of Cu²⁺ associated disorders like Wilson’s disease and in the detection of elevated lactate levels which are associated with wide range of pathologies like mitochondrial diseases, cerebral ischemia and cancer.