Experimental and theoretical investigation of the fluorescent detection of lysine by using a flexible pincer probe

A novel Schiff-base fluorescent probe (SA) has here been designed for lysine detection. A condensation reaction between thiophene-2-carboxaldehyde and 1,4-succinohydrazide was then used. The SA showed a selective “turn-on” fluorescence response (425 nm) to lysine in a pH-stable dimethyl sulfoxide (DMSO)/H₂O system (3:2, pH = 7.2), thereby achieving a detection limit of 8.21 × 10 −8  M. Both experimental and computational studies revealed that the SA formed a flexible V-shaped cavity via intramolecular non-covalent interactions. An adaptive encapsulation of lysine through synergistic O-H···N/O-H···O hydrogen bonds and σ-π interactions could, thereby, form a stable 1:1 complex. The present study has developed a rational design strategy for dynamic molecular probes and advanced high-performance sensing platforms for biomolecules.