Zn-metal organic framework containing electron rich linkers and film preparation for applications in antibiotic detection

A Zn-metal organic framework has been synthesized, [Zn4(ad)3(BPTC)(H2O)4]center dot 0.75ad center dot 0.25NO3 center dot 2.5DMF center dot 2.5H2O (ZnAB MOF) (ad = adenine, BPTC = biphenyl-3,3 ',5,5 '-tetracarboxylic acid) and characterized by X-ray single crystallography. The crystal structure reveals a 3D framework with two differently sized channels with the structure confirmed by IR, TGA and elemental analysis. This MOF has also been prepared in the form of a MOF film on a Zn metal sheet in situ with one continuous layer 60 mu m thick. The materials fluoresce at 352, 433 and 355, 423 nm (lambda ex = 310 nm), for MOF powder and MOF film, respectively. The fluorescence is quenched by nitrofuran antibiotics allowing the MOF to be used in their detection. Specifically, the nitrofuran antibiotics nitrofurazone (NFZ) and nitrofurantoin (NFT) exhibit significant quenching. ZnAB MOF powder shows higher sensitivity than the ZnAB MOF film with higher fluorescence quenching, Stern-Volmer constant (KSV) and limit of detection (LOD). However, the ZnAB MOF film exhibits superior repeatability for nitrofuran detection. Fluo-rescence quenching of NFZ and NFT may occur via fluorescence resonance energy transfer (FRET) and/or photoinduced electron transfer (PET).