Solvent induced two Cd-MOFs as luminescent sensors for picric acid, Fe3+ and Cr2O72-

Two new metal-organic frameworks (MOFs) [Cd3(NTB)2(DPP)(DMA)2]•4DMA (CUST-551) and [Cd3(NTB)2(DPP)2]•3DMA•H2O (CUST-552), (H3NTB ​= ​4,4′,4″-nitrilotrisbenzoic acid; DPP =1,3-di(4-pyridyl)propane; DMA =N,N-dimethylacetamide), were obtained from solvent induction strategy. Single-crystal X-ray diffraction analyses showed that CUST-551 and CUST-552 are both three-dimensional architectures with diverse topologies. The topological analysis revealed that the topology of CUST-551 is based on 3-8-connected net with the point symbol {43·624·8}{43}2, but CUST-552 is 3-10-connected with the point symbol {43}2{48·66·827·124}{4}2. Luminescence studies show that CUST-551 and CUST-552 display highly sensitive, selective, and recyclable properties in the detection of picric acid (PA, also called 2,4,6-trintrophenol, TNP), Fe3+ and Cr2O72−. In addition, the possible fluorescence quenching mechanism was explored.