Two Schiff Bases with ─N═CH─ Fragment at Different Positions of the Pyridine Skeleton on Photophysical Performances and Their Latent Fingerprint Detection

Abstract To further explore the application of Schiff bases in latent fingerprint detection, two Schiff bases containing ─N═CH─ fragment at different positions on the pyridine skeleton, which py‐3‐TPA with ─N═CH─ fragment at 3‐position of pyridine and that of locating at 2‐position of pyridine for py‐2‐TPA , were synthesized. Both Schiff bases displayed the solvent‐dependent behaviors in organic solvents of different polarities in emission spectra, and their solid state were luminescent under a UV lamp, which both could be well explained by time‐dependent density functional theory calculations, and the aggregation‐induced emission properties in THF/water mixtures were observed. Furthermore, the latent fingerprint on the surfaces of three substrates could visualize using two compounds, which could clearly identify three levels fingerprints features details. This work establishes a foundation for the development of Schiff‐base fluorescent dyes for practical application in the field of the latent fingerprint detection.