Pyridine-Induced Multifunctional Fluorescent Probes for Latent Fingerprint Imaging and Photoprinting Applications

A pyridine-containing heterocyclic fluorescent probe， N，N-diphenyl-4-（pyridin-4-yl）aniline （TPA-Py）， with a D-π-A architecture， along with its amphiphilic derivative 1-（2-Hydroxyethgl）-4-［4-（diphenylamine）phenyl］pyridin-1-ium （TPA-PyBr）， was synthesized， and their photophysical properties were systematically investigated. The experimental results demonstrated that TPA-Py exhibits pronounced acidochromic behavior， with its fluorescence emission peaks shifting from 415 nm to 550 nm upon protonation of the pyridyl group. Furthermore， TPA-Py exhibits fluorescence color changes in response to polar matrices， showing a remarkable bathochromic shift of over 160 nm as the concentration of poly（pentafluorophenyl acrylate） （pPFPA） increases. Compared with TPA-Py， TPA-PyBr exhibits improved aqueous solubility and aggregation-induced emission （AIE） behavior. This enables TPA-PyBr to achieve high-contrast fluorescent imaging of latent fingerprints in purely aqueous media by selectively targeting lipid-rich microdomains through hydrophobic interactions， thereby overcoming issues of biological sample degradation caused by organic solvent dependency in conventional probes. In addition， the TPA-Py-doped poly（methyl methacrylate） （PMMA） film achieves photoactivable room-temperature phosphorescence， showcasing its capability for erasable optical printing. This work explores the multifunctional capabilities of pyridine-based fluorescent probes in applications such as acid-responsive sensing， microenvironment monitoring， fingerprint visualization， and optical printing， providing valuable insights for the development of intelligent， responsive optoelectronic materials.