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[Display omitted] • UV sensing sensitivity reaches μW/cm2 level using color spaces. • Naked-eye-based dosimetry is enabled by wearable UV sensor. • UV radiation warning is achieved based on smart UV sensing textile. • High fatigue resistance, low-cost fabrication and nice portability. A dual-channel photochromic Schiff base HBA is reported herein, which undergoes a reversible tautomerism in response to UV exposure, showing visible changes in both color and fluorescence. The spectral behavior, fatigue resistance, sensitivity are studied. The quantification of photochromic fluorescence/color change is solved by applying color spaces and chromatic aberration. HBA is further fabricated into low-cost wearable sensor and smart textile, enabling visual feedback under UV radiation. It demonstrates a low-costing platform for naked-eye-based dosimetry of outdoor UV radiations, providing an early warning for excessive UV exposure. [ABSTRACT FROM AUTHOR]

This study presents the synthesis, crystallographic data and photophysical properties of a donor-acceptor (D-A) compound, methoxybenzylidene methanone Schiff base (HMPPM). It shows remarkable vapofluorochromism, embodied as turn-on red fluorescence in response to volatile organic compounds (VOCs), with fast response and high signal contrast. HMPPM is further developed into a cellulose sensor via dip-dying method for VOCs detection. We further use RGB and CIELAB color spaces to quantify the vapofluorochromic fluorescence. The limits of detection (LOD) of the sensor reach ppm level. Furthermore, it was fabricated into a wearable VOC sensor, with the introduction of an endogenous/exogenous reference, which conduces to high accuracy and visual identification. The cellulose sensor can be tailored into diversified patterns, with controllable shape and size, which facilitated the encapsulation into various wearables, including shoes, hat and smart band, etc. , succeeding in scenario-based VOCs detection. In addition, we built a smartphone-based sensing platform based on HMPPM , which achieves a ppm-level LOD in VOCs monitoring. [Display omitted] • Turn-on vapofluorochromic effect toward VOCs. • Innovative quantitative method using fluorescent reference with image technology. • Portable VOC sensor compatible with smartphone platform and wearable applications. • Facile synthesis, low-cost preparation, fast response and ppm sensitivity. [ABSTRACT FROM AUTHOR]

In this study, a diethylamino methanone Schiff base (HBAPE) was reported. Its synthesis, quantum chemical calculations, photophysical behaviors containing aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) were systematically studied. More importantly, HBAPE exhibits photochromism in response to UV light via reversible tautomerism, where a remarkable color change in both absorption and emission was observed. Thermal treatment or visible-light exposure would activate the reverse reaction to restore the compound to its pristine state. The color change in the photochromic process is well quantified by RGB and CIE L * a * b * color space, and the latter exhibits high compatibility and accuracy owing to the utilization of the derived color shift (Δ E* Lab). Based on Δ E* Lab analysis, the limits of detection (DL) are calculated to be as low as 6.2 μW/cm2 (by manual color picking) and 2.6 μW/cm2 (by chromatic meter measurement), suggesting high sensitivity towards UV radiation. We further develop a prototype of data-recording film that can write and erase binary data by UV and heating/visible-light, respectively. The data recording film shows high signal contrast by utilizing Δ E* Lab as the output, achieving nice rewritability. A strategy for data encryption-decryption was developed. With an inert compound as the background covering, the information can be concealed via heating or visible-light, and revealed by UV radiation, providing a reliable strategy for information safety. [Display omitted] • Using CIE L * a * b * and color shift to quantify the photochromic change. • A prototype of rewritable data storage using color shift as binary signal. • A bimolecular data-recoding system enabling information encryption-decryption. • Facile synthesis, low-cost fabrication, reusability and μW/cm2 level sensitivity. [ABSTRACT FROM AUTHOR]

We herein present a donor-acceptor (D-A) luminogen, (E)-(3- (((2-hydroxynaphthalen-1-yl)methylene)amino)phenyl)(phenyl)methanone (HNPMO), with both intramolecular charge transfer and aggregation-induced emission (ICT + AIE) properties. It was developed into a film sensor by drop-casting, exhibiting sharp increase in emission when exposing to various volatile organic compounds (VOCs), such as benzene series (e.g. , toluene), common organic solvents (e.g. , ethyl acetate) and alcohols (e.g. , methanol), etc. Spectral analysis and quantum chemical calculations confirmed that the turn-on response can be ascribed to the transition from the disordered molecular arrangement to the optimized conformation driven by VOCs in the gas phase, with some major influence factors including volatility, molecular size, structural compatibility and steric hindrance. In addition, the fluorescent response is quantified by well-established image technology, using RGB and Lab color space. In the sensitivity test, Lab color shift (Δ E Lab) was used to estimate the limit of detection (LOD) of the HNPMO film sensor, which gives a linear relation with VOC concentration. The resulting LOD value is as low as 7.04 mg/m3 (1.8 ppm), suggesting high sensitivity intrinsic to such turn-on type sensor. We further fabricate a wearable sensor device based on HNPMO film, employing a reference substance which is inert to VOCs. Thus the presence of VOCs can be confirmed by the Lab color shift between HNPMO and the inert reference. By cutting and shaping, the film sensor applies to gloves, labor suits and even nails. It is capable of point-of-care detection of VOCs, providing an early warning of air contamination in various scenarios. [Display omitted] • Design and synthesis of a hydroxynaphthalene benzophenone Schiff base. • Turn-on fluorescent response to volatile organic compounds. • Using color space and color shift to quantify the fluorescent response. • Facile fabrication, fast response and ppm sensitivity. • Easy fabrication into a wearable device for scenario-based applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A luminogen showing AIE, ICT and photochromism. • The utilization of with RGB / Lab color space and chromatic aberration for quantitative analysis. • Facile fabrication, cycle use, low cost and high sensitivity with the UV sensor. • Paper-based wearable UV sensor in scenario-based applications. • Naked-eye or machine-readable dosimetry of UV radiations. We report in this study a photochromic benzonitrile Schiff base, (E)-4-((2-hydroxy-4-methoxybenzylidene)amino)benzonitrile (HMBAB). The molecular design, synthesis, aggregation-induced emission (AIE) as well as the quantum chemical calculations were outlined. In particular, HMBAB would undergo a reversible tautomerism in response to UV exposure, exhibiting remarkable changes in both absorption and emission: the compound shows yellow color and green-yellow luminescence; after UV exposure, the changes into orange-red while the luminescence is dramatically quenched, accompanied by a large bathochromic-shift. In addition, the photochromic state can be fully recovered via thermal treatment. Such reversible dual-channel photochromism was investigated using UV–vis reflectance spectroscopy and colorimeter, wherein a gradient change with time and a high fatigue resistance in cycle use was recorded. The photochromism is quantified by well-established RGB and Lab color space, in which the color change can be accurately analyzed by the chromatic aberration (Δ E* Lab). Sensitivity test gives a two-stage linear relation between Δ E* Lab and UV intensity, by which a limit of detection (LOD) as low as 67 μW/cm2 is obtained. HMBAB was further fabricated into a paper-based wearable sensor, capable of being integrated into a chest card or a bracelet. It exhibits various degrees of color change in different sunlight environments, which can be readily observed by naked eyes, providing an early warning for high-dose UV radiations. [ABSTRACT FROM AUTHOR]