Zr(IV)-Based Metal-Organic Framework with T-Shaped Ligand: Unique Structure, High Stability, Selective Detection, and Rapid Adsorption of Cr2O72- in Water

Dichromate is known for severe health impairments to organisms. New and valid strategies have been developed to rapidly detect and efficiently remove this pollutant. Constructing stable luminescent metal-organic frameworks (MOFs) for dichromate recognition and removal from aqueous solution could provide a feasible resolution to this problem. Herein, a new luminescent Zr(IV)MOF, Zr6O4(OH)(7)(H2O)(3)(BTBA)(3) (BUT-39, BUT = Beijing University of Technology) was constructed through the reaction of a newly designed functionalized T-shaped ligand 4,4',4"-(1Hbenzo[d]imidazole-2,4,7-triyl)tribenzoic acid (H(3)BTBA) with zirconium salt. BUT-39 has a unique porous framework structure, in which Zr-6 cluster acts as a rare low-symmetric 9-connected node and BTBA(3-) as a T-shaped 3-connected linker. As far as we know, this represents the first case of a (3,9)-connected Zr(W)-MOF. BUT-39 could retain its framework integrity in boiling water, 2 M HCI aqueous solution, and pH 12 NaOH aqueous solution. Due to its good water stability and strong fluorescent emission, BUT-39 is then employed in fluorescence sensing for various ions in aqueous solution and shows good performance toward Cr2O72- selectively, at a low concentration and a short response time (<1 min). Simultaneously, it also exhibits excellent capacity to rapidly capture Cr2O72- (within 1 min) with a high uptake up to 1 mmol g(-1). Taking advantage of its excellent stability, sensitive and selective sensing, as well as rapid and high adsorption, BUT-39 is expected to be useful in Cr2O72- detection in and removal from water.