AIE-active dipyridinyltriphenylamine for dual-model visualization of latent fingerprints

The development of highly efficient latent fingerprints technology (LFPs) on different background remains extremely vital for forensic and criminal investigations. In this work, a pure organic molecular sensor (DPTPA1) was designed to image LFP with strong signal-to-noise ratio by optimizing the imaging technology. DPTPA1 exhibits aggregation-induced emission (AIE) properties in both aqueous solution and solid state. Two pyridine moieties and one aldehyde moiety were introduced as the end-capped units. DPTPA1 exhibits the typical solvatochromic effect whose maximum emission wavelengths red-shift from 410 nm to 540 nm with the increasing polarity of solvents. The obvious emission of DPTPA1 in the aqueous solution is observed around 500 nm (ϕ = 9.6%). Both cyanoacrylate glue fuming (CGF) and powder dusting (PD) methods were used to obtain the fluorescent images of LFP on glass, tinfoil, steel and plastic substrates. Among them, the CGF method can image the clear second level details of LFP on the glass and tinfoil. The PD method using DPTPA1-loaded silica gel material can obtain the high quality LFP images on the curved surface of all four substrates. This work provides a strategy for lowing the cost in the broad fields of LFPs imaging.