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.

Exploring a covalent organic framework (COF) material as an efficient metal-free photocatalyst and as an adsorbent for the removal of pollutants from contaminated water is very challenging in the context of sustainable chemistry. Herein, we report a new porous crystalline COF, C6-TRZ-TPA COF, via segregation of donor–acceptor moieties through the extended Schiff base condensation between tris(4-formylphenyl)amine and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)trianiline. This COF displayed a Brunauer–Emmett–Teller (BET) surface area of 1058 m2 g–1 with a pore volume of 0.73 cc g–1. Again, extended π-conjugation, the presence of heteroatoms throughout the framework, and a narrow band gap of 2.2 eV, all these features collectively work for the environmental remediation in two different perspectives: it could harness solar energy for environmental clean-up, where the COF has been explored as a robust metal-free photocatalyst for wastewater treatment and as an adsorbent for iodine capture. In our endeavor of wastewater treatment, we have conducted the photodegradation of rose bengal (RB) and methylene blue (MB) as model pollutants since these are extremely toxic, are health hazard, and bioaccumulative in nature. The catalyst C6-TRZ-TPA COF showed a very high catalytic efficiency of 99% towards the degradation of 250 parts per million (ppm) of RB solution in 80 min under visible light irradiation with the rate constant of 0.05 min–1. Further, C6-TRZ-TPA COF is found to be an excellent adsorbent as it efficiently adsorbed radioactive iodine from its solution as well as from the vapor phase. The material exhibits a very rapid iodine capturing tendency with an outstanding iodine vapor uptake capacity of 4832 mg g–1.

Designing an efficient catalyst for a sustainable photoelectrochemical water oxidation reaction is very challenging in the context of renewable energy research. Here, we have introduced a new semiconducting porous zinc–thiolate framework via successful stitching of an “N” donor linker with a triazine-based tristhiolate secondary building unit in the overall architecture. The introduction of both linker and tristhiolate ligand synergistically modifies the architecture by making it a rigid, crystalline, three-dimensional, thermally stable, and porous framework. Our novel zinc–thiolate framework is used as an n-type semiconductor as revealed from the solid-state UV–vis DRS spectroscopic analysis, ac and dc conductivity analysis, and Mott–Schottky plot. This n-type semiconductor-based zinc–thiolate framework is utilized in the photoelectrochemical water oxidation reaction. It displayed a very high efficiency for a visible-light-driven oxygen evolution reaction (OER) in a KOH medium using standard Ag/AgCl as the reference electrode. The superiority of this material was further revealed from the low onset potential (0.822 mV vs RHE), high photocurrent density (0.204 mA cm–2), good stability, and high O2 evolution rate (77 μmol g–1 of oxygen evolution within 2 h), and a good efficiency (ABPE 0.42%, IPCE 29.6% and APCE 34.5%). Furthermore, the porosity in the overall framework seems to be a blessing to the photoelectrochemical performance due to better mass diffusion of the electrolyte. A detailed mechanism for the OER reaction was analyzed through density functional theory analysis suggesting the potential future of this Zn–thiolate framework for achieving a high efficiency in the sustainable water oxidation reaction.

Metal-organic frameworks (MOFs) containing multiple carboxylate and sulfonate linkers together with positively charged rare earth metals can offer new opportunities in heterogeneous catalysis. High efficiency of CO2 fixation reaction at...

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