Two-dimensional lanthanide coordination polymer nanosheets for detection of FOX-7
Despite the recent surge of interest in two-dimensional (2D) inorganic nanosheets derived from photoactive coordination polymers of lanthanide ions having interesting optical properties, research in this area is still in its infancy. Luminescent lanthanide ions, Eu(III) or/and Tb(III), as well as a bis-terpyridine ligand (L), used in this study as the building blocks for the synthesis of archetypical layered structure of coordination polymers (CPs) (L•Eu / L•Tb). 2D-nanosheets achieved through exfoliation of the layered precursor of CPs in a suitable solvent system following a sonication-assisted strategy. These nanosheets exhibit lateral sizes on the micrometer scale (0.3−1 µm) and ultrathin thickness of 2−6.5 nm. 1,1-diamino-2,2-dinitroethene or FOX-7 is an insensitive high explosive, in a binder mixture slightly superior detonation velocity of 8870 m/s in compare to RDX. The insensitive nature of FOX-7 makes it a key component for the development of low vulnerable high explosive compositions for further application in weaponry. The growing demand of FOX-7, for use as a suitable replacement of conventional explosives is of serious concern to human security. Achieving the rapid and efficient detection of this unexplored explosive is a challenging task. In the present study, the developed luminescent nanosheets used for the first time at micromolar level detection of FOX-7 both in solution and solid-state. A visually distinct color change of the nanosheets from red (L•Eu) and green (L•Tb) to colorless witnessed during detection process. Notably, the solid-state detection technique could exploit for developing commercial spray kit for quick onsite screening of this important explosive.