A new multifunctional anionic 3D Zn(ii)-MOF based on heptanuclear clusters: selective adsorption of organic dyes and a dual-emitting sensor for nitroantibiotics

Abstract

A multifunctional anionic Zn-MOF, formulated as {[NH₂(CH₃)₂][Zn₇(μ₃-OH)₃(L)₆(H₂O)]·24H₂O·6DMA}_n (1) (where H₂L = 6-methoxy-2,2′-sulfone-4,4′-dicarboxylic acid and DMA = dimethylacetamide) has been solvothermally synthesized, which is based on rare heptanuclear [Zn₇(μ₃-OH)₃(COO)₁₂] clusters possessing large 3D intersecting channels. Through a cation-exchange process, 1 can selectively adsorb cationic organic dyes, and the adsorption capacities for methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) are 219.9, 114.6 and 197.6 mg g⁻¹, respectively. Moreover, the obtained RhB@1 composite features dual-emissive characteristics and can serve as a dual-channel sensor for selective sensing of traces of NF antibiotics (NFT and NFZ), with detection limits of 0.89 μM and 0.95 μM, respectively. The mechanism study shows that the quenching process is mainly ascribed to the synthetic effect of IFE and FRET.