AIE + ESIPT based red fluorescent aggregates for visualization of latent fingerprints

Fluorescent molecules are extensively employed in (bio)sensing and bioimaging but their applications in the visualization of fingerprints are less reported due to their inherited aggregation-caused quenching (ACQ) mechanism in the solid state (aggregated form). DPSA undergoes self-assembly to form aggregates with rod-like structures in a 90% H2O : CH3CN mixture evident from dynamic light scattering (DLS) and scanning electron microscopic (SEM) techniques. The self-assembled diphenylpyrimidinone (DPSA) derivative shows aggregation-induced emission (∼24 fold) in a >90% H2O : CH3CN mixture with orange-red fluorescence (λmax 564 nm). The red fluorescent aggregates of DPSA show applications in the visualization of latent fingerprints on aluminium, stainless steel and metal currency coin substrates. In addition, we established the individuality of three subjects based on information gathered at level one (pattern of arch, loop or whorl) and level two (minutiae details of dots, bifurcation, ridge ending, core and delta).