Hierarchical Dual-Mode Efficient Tunable Afterglow via J-Aggregates in Single-Phosphor-Doped Polymer.

The development of polymer-based persistent luminescence materials with color-tunable organic afterglow and multiple responses is highly desirable for the applications in anti-counterfeiting, flexible displays and data-storage. However, achieving efficient persistent luminescence from a single-phosphor system with multiple responses remains a challenging task. Herein, a hierarchical dual-mode emission system is developed by doping 9H-pyrido[3,4-b]indole (PI2) into an amorphous polyacrylamide matrix, which exhibits color-tunable afterglow due to excitation-, temperature- and humidity-dependence. Notably, the coexistence of isolated state and J-aggregate state of the guest molecule not only provides excitation-dependent afterglow color, but also leads to hierarchical temperature-dependent afterglow color resulting from different thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) behaviors of the isolated and aggregated states. The complex responsiveness based on the hierarchical dual-mode emission can serve for security features through inkjet printing and ink-writing. These findings may provide further insight into the regulated persistent luminescence by isolated and aggregated phosphors in doped polymer systems and expand the scope of stimuli-responsive organic afterglow materials for broader applications.

A wireless fluorescent sensing device for on-site closed-loop detection of hydrazine levels in the environment.

Given the extensive need for the detection of hydrazine (N2H4) in the biomedical and chemical-pharmaceutical sectors, there is a necessity to devise a fast, sensitive, specific, and portable technique for precisely quantifying hydrazine at environmental levels. In our work, an "OFF-ON" type fluorescent probe namely 2-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)isoindole-1,3-dione (NAP), which was inspired by the "Gabriel" reaction, was synthesized. The NAP fluorescent cellulose film successfully achieved the detection of hydrazine vapor with a LOD = 0.658 ppm. Compared to previous qualitative methods for detecting hydrazine, this study successfully achieved quantitative identification of hydrazine at low concentrations. In addition, a portable sensor device based on NAP cellulose film was successfully integrated, enabling ultra-sensitive, wireless, remote, and real-time detection of N2H4 vapor. It was determined that the probe (NAP) exhibited excellent detection performance when applied to various environmental samples including distilled water, tap water, creek water, soil and plants. This study introduces a potentially effective approach for detecting hydrazine in real-world settings.

Controllable synthesis of conjugated microporous polymer films for ultrasensitive detection of chemical warfare agents.

Nerve agents, one of the most toxic chemical warfare agents, seriously threaten human life and public security. The high toxicity of nerve agents makes the development of fluorescence sensors with suitable limit of detection challenging. Here, we propose a sensor design based on a conjugated microporous polymer film for the detection of diethyl chlorophosphate, a substitute of Sarin, with low detection limit of 2.5 ppt. This is due to the synergy of the susceptible on-off effect of hybridization and de-hybridization of hybrid local and charge transfer (HLCT) materials and the microporous structure of CMP films facilitating the inward diffusion of DCP vapors, and the extended π-conjugated structure. This strategy provides a new idea for the future development of gas sensors. In addition, a portable sensor is successfully integrated based on TCzP-CMP films that enables wireless, remote, ultrasensitive, and real-time detection of DCP vapors.

Visualization of Ultrasensitive and Recyclable Dual-Channel Fluorescence Sensors for Chemical Warfare Agents Based on the State Dehybridization of Hybrid Locally Excited and Charge Transfer Materials.

Simple and fast detection of chemical warfare agents vapor is necessary and urgent to fight against uncertain terrorist attacks and wars. In this contribution, inspired by the design of the hybrid locally excited and charge transfer (HLCT) excited state, two fast and highly sensitive visualization and fluorescence probes for DCP detection with relative small interstate coupling (J) TPA-2AC and TPA-9AC are reported. Upon exposure to saturated DCP vapor, the TPA-9AC test strips exhibited a rapid fluorescent response in no more than 1 s, accompanied by a change of the color from green to red. The detection limit of the test strips can be estimated as sensitive as 0.15 ppb, which is far superior to the "harmless" level (7 ppb) of human response to acute sarin exposure. More impressively, the fluorescent intensity of the test strips can be quickly restored when exposed to ammonia vapor for cyclic utilization, demonstrating an application prospect in the real-time detection of chemical warfare agents.