Excess and deficiency of iron(III) and antibiotics from normal permissible limits will induce serious disorders, so their detection is important but challenging. In this work, by introducing a new amino triazole ligand N¹-(4-(1H-1,2,4-triazole-1-yl)benzyl)-N¹-(2-aminoethyl)ethane-1,2-diamine (L), a series of Cd(II)-based metal–organic frameworks (MOFs) [Cd₃(BDC)₃(DMF)₂] (1), [Cd(L)(BDC)]₂·2DMF·H₂O (2), [NaCd₂(L)(BDC)_2.5]·9H₂O (3), [Cd₂(L)(2,6-NDC)₂]·DMF·5H₂O (4) and [Cd₂(L)(BPDC)₂]·DMF·9H₂O (5) were synthesized. MOFs 1, 2 and 3 obtained under the same conditions with the same auxiliary ligand (H₂BDC) but different amounts of alkali (NaOH) show distinct 3D, 1D and 3D framework structures, respectively, in which L and BDC²⁻ exhibit varied coordination modes. 4 and 5 with 3D structures were isolated by using longer auxiliary ligands of 2,6-H₂NDC and H₂BPDC. The porosity and excellent fluorescence performance of 3, 4 and 5 make them potential luminescent sensors for Fe(III) and antibiotics. The results show that 3, 4 and 5 represent high sensitivity for the detection of Fe(III) ions with detection limits of 155 ppb for 3, 209 ppb for 4 and 297 ppb for 5 due to the existence of open channels and chelating NH₂ sites. In addition, the strong emissions of 3, 4 and 5 can be quenched efficiently by trace amounts of NFs (nitrofurazone, NZF; nitrofurantoin, NFT; furazolidone, FZD) antibiotics even in the presence of other competing antibiotics such as β-lactams (penicillin, PCL). They are responsive to NZF with detection limits of 162 ppb for 3, 75 ppb for 4 and 60 ppb for 5.

This review focuses on the recent development of luminescent MOFs with synthetic approaches and their application in sensing biomolecules.