A vapofluorochromic dimethylaniline naphthol Schiff base used for fabricating smart textiles for VOCs detection

Abstract

This work presents the synthesis and photophysical properties of a vapoluminescent compound, (E)-1-(((4-(dimethylamino)phenyl)imino)methyl)naphthalen-2-ol (DPINO), and further studies its photophysical properties, mainly including twisted intramolecular charge transfer (TICT) and vapoluminescent behaviors. DPINO emits wreak fluorescence deposited on cellulose substrate, but exhibits a turn-on effect in response to various kinds of VOCs, showing fast response and high visual identification. Through spectral analysis, it is found that the physical interaction between DPINO and VOCs is influenced by multiple factors, including volatility, structural similarity and molecular size (steric hindrance), leading to varying degrees of fluorescence response toward different VOCs. Using RGB (red-green-blue) and CIE L*a*b* (CIELAB) color spaces, the output signals are well-quantified, deriving color shift (ΔE*) for sensitivity evaluation. And the limit of detection (LOD) is calculated to be 7.4 mg/m3 (2.22 ppm) and 2.4 mg/m3 (0.72 ppm), based on RGB and CIE L*a*b*, respectively. We further fabricated a bimolecular smart textile by dip-dyeing method, which includes the present DPINO as well as an inert luminogen MMA, i.e., fluorescent reference. The DPINO-MMA bimolecular smart textile can be freely designed in shape and size, and further made into smart clothes labels, e.g., chest card, arm band and wrist band. In scenario-based experiments, the smart textile shows notable turn-on fluorescence in response to VOCs, enabling high visual identification and real-time feedback.