Sensitive and rapid identification of illicit drugs in a non-contact mode remains a challenge for years. Here we report three film-based fluorescent sensors showing unprecedented sensitivity, selectivity, and response speed to the existence of six widely abused illicit drugs, including methamphetamine (MAPA), ecstasy, magu, caffeine, phenobarbital (PB), and ketamine in vapor phase. Importantly, for these drugs, the sensing can be successfully performed after 5.0 × 105, 4.0 × 105, 2.0 × 105, 1.0 × 105, 4.0 × 104, and 2.0 × 102 times dilution of their saturated vapor with air at room temperature, respectively. Also, presence of odorous substances (toiletries, fruits, dirty clothes, etc.), water, and amido-bond-containing organic compounds (typical organic amines, legal drugs, and different amino acids) shows little effect upon the sensing. More importantly, discrimination and identification of them can be realized by using the sensors in an array way. Based upon the discoveries, a conceptual, two-sensor based detector is developed, and non-contact detection of the drugs is realized.

BTEX (benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene) represents a group of volatile organic compounds (VOCs) and constitutes a great threat to human health. However, sensitive, selective, and speedy detection of them on-site and in the vapor phase remains a challenge for years. Herein, we report a film-based fluorescent approach and a conceptual sensor, which shows unprecedented sensitivity, speed, and reversibility to the aromatic hydrocarbons in the vapor phase. In the studies, pentiptycene was employed to produce a nonplanar perylene bisimide (PBI) derivative, P-PBI. The compound was further utilized to fabricate the film. The novelty of the design is the combination of capillary condensation and solvent effect, which is expected to enrich the analytes from vapor phase and shows outputs at the same time. Importantly, the film permits instant response (∼3 s) and real-time identification (<1 min) of benzene and toluene from other aromatic hydrocarbons. The experimental detection limits (DLs) of the six analytes are lower than 9.2, 2.7, 1.9, 0.2, 0.4, and 0.4 ppm, which with the exception of benzene, are significantly lower than the NIOSH recommended long-term exposure limits. More importantly, the film is photochemically stable, and more than 300 repetitive tests showed no observable bleaching. In addition, the sensing is fully reversible. The superior performance of the film device is in support of the assumption that the combination of capillary condensation and solvation effect would constitute an effective way to design high-performance fluorescent films, especially for challenging chemical inert and photoelectronically inactive VOCs.

In situ, online, fast, and sensitive detection and discrimination of explosives, illicit drugs, and volatile organic compounds via vapor sampling is a challenge for many years. The highly efficient and noncontact detection of 15 types of chemicals mentioned above using a film‐based fluorescent sensor array is reported herein. Importantly, the presence of water, toiletries, fruit, dirty clothes, and other interferences has little effect upon detection. Discrimination of the controlled chemicals is realized using a pattern recognition strategy. Meanwhile, a conceptual detector based on a sensor array is constructed and successfully used for simulated field tests. It is strongly believed that the present work not only provides a powerful fluorescent technique for efficient detection and discrimination of controlled chemicals with remarkably different properties but also demonstrates that arraying a single sensor is a promising strategy to mitigate the limitations of conventional film‐based fluorescent sensors.

Reliable and nondestructive monitoring of food quality is of great importance in sustaining life and promoting good health. Herein, we developed sensitive, fast, reversible, and nanometer-thick fluorescent films for the nondestructive evaluation of fish freshness. The nanofilms were prepared via the dynamic condensation of tetraphenylethylene derivative (TPEBA) with Calix[4]pyrrole derivative (CPTH) at the humid air/DMSO interface. The amorphous nanofilm is uniform with the thickness in the range of 12∼58 nm. Owing to the aggregation-induced emission (AIE) property of TPEBA, the nanofilm is highly emissive with a Stokes shift of ∼175 nm. The typically designed chemical composition and nanostructure endow the film-preferable affinity to amine vapors, and the networked structure allows fast mass transfer, which lays foundation for high-performance sensing. With an optimized nanofilm-based sensor, biogenetic amines were sensitively, selectively, and reversibly detected. The detection limit (DL) for trimethylamine (TMA) is 0.89 ppm. Typically, interference from water can be neglected; thus, the nondestructive evaluation of fish freshness was realized. Moreover, a portable seafood freshness detector was conceptually built.

A reversible mechanochromic luminescent material based on a simple tetrahedral monoboron complex (B-1) is described. Interestingly, in addition to amorphous powders (P), the compound could exist in three unique crystal states (A, B, and C), showing efficient green-to-red luminescent colors, which is a result of wane and wax of dual emissions of the compound. Surprisingly, one of the emissions increases significantly with increasing temperature, fully offsetting the quenching effect of temperature-assisted internal conversion process. The four states are fully interconvertible through grinding and heating, allowing color writing/painting with a single ink.