Molecular Probe for Specific Recognition of TKX-50: 'Luminescence-ON' Response and its Integration to a Smart Device for Surveillance.

In response to the growing concerns about the unauthorized use of advanced secondary explosives such as TKX-50 against non-combatant targets, there is an urgent need for effective detection methods or techniques to ensure efficient security screening, homeland security, and public safety. Herein, a new polymeric receptor (IV) derived from functionalized tetraphenylethylene moiety (TPE) and 1,3,5-tris(4-aminophenyl)benzene (TAPB)  moieties for the efficient detection of TKX-50 through a 'switch ON' luminescence response upon specific binding to the explosive, is reported. The observed 'luminescence ON' response is rationalized based on a charge transfer complex formation between TKX-50 and the polymeric receptor IV (Ka = 1.7 × 104 m-1). This is validated by the steady and excited-state luminescence studies, along with detailed computational studies. The authors' presumptions are further validated with adequate control studies using an appropriate monomeric derivative (III) of TPE. Moreover, this 'luminescence ON' response can be integrated into a smart and user-friendly Internet of Things (IoT)-based prototype device. This device can effectively convert optical responses into digital output to develop an optical device for real-time detection of TKX-50 in solution. This lightweight, portable device is ideally suited for remote surveillance and monitoring of TKX-50; such examples are rare in contemporary literature.