Stretchable nanofibrous membranes for colorimetric/fluorometric HCl sensing: Highly sensitive charge-transfer excited state

Abstract The detection and sensing of acidic gases by optical sensors are of great importance in the fields of chemistry, environment and related industrial process. However, stretchable, low-cost, and tailorable sensors with high sensitivity and fast response remain a great challenge. In this work, we report a twisting donor–acceptor fluorophore ( DBPA ) with a hybridized local and charge-transfer excited state ( HLCT ) can serve as a visible dual-channel (colorimetric and fluorometric) sensor towards acid gas detection. Combination of the locally excited ( LE ) state and the high sensitive charge-transfer ( CT ) state, DBPA in aggregated state presents a high PL efficiency ( η PL  > 76%), which exhibits over 98% PL quenching and a clear color difference ( ΔE over 20 ) upon exposure to HCl gas. By incorporation of HLCT -active DBPA molecule into an elastomer host through an electrospinning process, new flexible and stretchable nanofiber films ( SNMs ) were prepared. Compared to non-porous rigid films, the sensitivity and response time of SNMs were obviously improved due to their large surface area and high porosity. It can be expected that, by taking the advantages of easy mass-production and low cost, such SNMs could be a promising optical material for practical sensory application.