A styryl-benzothiadiazole derivative with aggregation-induced enhanced emission for latent fingerprint recognition

An aryloxy- and a biphenyl-substituted styryl-benzothiadiazole derivatives were designed and synthesized aiming aggregation-induced enhanced emission (AIEE). In solutions, compounds presented absorption in the blue region (404–421 nm) and fluorescence emission ranging from 503 to 578 nm. Moderate to high Stokes-shifts along with marked positive solvatochromism were observed for both compounds. The biphenyl derivative (5) has not displayed AIEE. In contrast, the aryloxy-substituted compound (4) presented enhancement of luminescence (I/I0 up to 5.7) in acetone solutions containing fraction of water (ƒw) from 65% up to >99%. The presence of nanoaggregates in these conditions were corroborated by dynamic light scattering measurements and via temperature-dependency of fluorescence. Finally, the luminescent nanoaggregates of 4 were applied in latent fingerprint recognition allowing their detection in glass and aluminum surface, with good differentiation between ridges and furrows as well as visualization of secondary level information (core, independent ridges, bifurcations, ridges terminations, ridges dots).