Series of highly stable Cd(II)-based MOFs as sensitive and selective sensors for detection of nitrofuran antibiotic

The abuse of antibiotics has caused global problems including critical environmental ecology impacts. Herein, four new metal-organic frameworks (MOFs) - {[Cd(HL)(bic)(H2O)]center dot 2H(2)O}(1), {[Cd-3(L)(2)(bbi)(2)(H2O)(2)]center dot 2H(2)O}(2), [Cd-3(L)(2)(bib)(2)(H2O)(2)] (3) and [Cd-3(L)(2)(idy)(2)] (4), where bic = 3,6-bis(imidazol-1-yl)-9H-carbazole, bbi = 1,1'-(1,4-butanediyl)bis(imidazole), bib = 1,4-bis(1-imidazoly)benzene and idy = 2-imidazol-1-ylpyridine - have been synthesized and fully characterized. 1 is a 1D chain with a large loop, stacked parallel to each other in 2D supramolecular layers by hydrogen-bonded and packing interactions. 2 and 3 are isostructural and show a 3D (3,8)-connected tfz-type network with (4(3))(2)(4(6).6(18).8(4)) topology. 4 has a 2D grid framework. The oxygen atom of the ether-bridging group acts as a Lewis base site, which improves the connection strength and allows the detection of 11 types of antibiotics through the fluorescence quenching effect. Among them, 2 exhibits sensitive and selective detection for nitrofural (NZF) (K-SV = 8.26 x 10(3) M-1 and LOD = 1.83 ppm). Moreover, the highly selective probe behavior towards NZF ions could be maintained even if there are other interfering antibiotics.