Latent fingerprint (LFP) detection is essential in criminal investigations, especially for identifying suspects. This study delves into the advancements in LFP imaging using artificial light-harvesting systems (ALHSs). These systems demonstrate high energy transfer efficiency and the antenna effect of BODIHYs (B1–B3) when combined with Rhodamine 6G (R6G), which led to the generation of high-resolution fluorescence images of LFPs, capturing details at levels 1–3 with great success. In these systems, BODIHYs (B1–B3) serve as a donor, while R6G serves as an acceptor. The BODIHYs were created from specific compounds: (E)-N′-(4-benzoylphenyl)picolinohydrazonoyl cyanide (L1), (Z)-N′-(4-benzoylphenyl)benzod-thiazole-2-carbohydrazonoyl cyanide (L2), and (Z)-ethyl 2-(benzodthiazol-2-yl)-2-(2-(4-benz-oylphenyl)hydrazono)acetate (L3). The ligands and BODIHYs exhibit strong emission properties in solution, aggregate, and solid states. The vital roles of various interactions in aggregation-induced emission (AIE; L2 and B1–B3) and aggregation-caused quenching (ACQ; L1) have been rationalized by X-ray single-crystal analyses. Notably, the hydrazone L3 contains a secondary hydrogen bond acceptor (−COOC2H5) and displays intramolecular hydrogen bonding, functioning as an effective molecular switch. Its ability to rapidly and reversibly transition between E and Z configurations under pH variations has been clearly demonstrated, which has practical application in inkless writing.
Yadav et al. (Tue,) studied this question.