Novel Nanoporous Ti-Phosphonate Metal–Organic Framework for Selective Sensing of 2,4,6-Trinitrophenol and a Promising Electrode in an Energy Storage Device

Abstract

Designing a multifunctional metal–organic framework (MOF) based on a novel ligand architecture for fluorescence sensing of explosives and energy storage applications is very challenging from the perspectives of sustainable chemistry. Herein, we report a novel tetradentate phosphonate ligand-based porous metal–organic framework material H8L-Ti-MOF, and it displayed selective recognition of 2,4,6-trinitrophenol (TNP) or picric acid in aqueous phase with a detection limit of 3.6 μM (0.82 ppm). Interestingly, the fluorescence intensity of the MOF was completely quenched in the presence of TNP, whereas other nitroaromatics/nitroaliphatics did not have subtle effects on the fluorescence intensity profile of this Ti-MOF. Experimental and DFT studies shed light on the mechanistic pathway of the host–guest interaction indicating RET-PET-ICT to be the best possible mechanism for specific TNP quenching phenomenon. A semiconductor device in conjunction with an explosive sensing application makes our MOF-based system a self-sustainable one in its congener. Further, this Ti-MOF has been utilized as an electrode for an asymmetric supercapacitor device (20.03 F/cm2 @0.1 mA/cm2 current density) with a very high cycling stability. The energy storage capacity of this Ti-MOF has been reflected from glowing of a LED after charging the assembly.