Self-assembled nanomaterials of naphthalene monoimide in aqueous medium for multimodal detection of picric acid

Picric acid (PA) is a menacing environmental pollutant on account of its high solubility in water. Extensive usage of picric acid as a handy chemical and go-to explosive in pharmaceutical and chemical industries has been posing alarming threats to the environment and public health. The detection of PA in aqueous medium and vapor state is extremely important for military and civilian safety. Here, we report the synthesis of water soluble 1, 8-naphthalimide (ANDI) and multimodal sensing applications of aggregated nano materials for nitro explosives such as picric acid (PA) in aqueous, solid surface and vapor phase. The ANDI nano aggregates demonstrated substantial selectivity and ultrasensitive detection of PA with exceptional quenching constant 7.23 x 106 M-1 and limit of detection 149 ppb. The quenching takes place due to ground state charge transfer complex formation between PA and ANDI. Equilibrium simulation and the potential of mean force calculations reveal that the ANDI selfassembly is stabilized by extensive 7C-7C interactions and the primary driving force behind the recognition of PA by the assembly is van der Waals interactions. ANDI aggregates would be potential materials for the construction of low cost and light weight nitroaromatic explosive sensors for future application.