A zinc complex for the detection of anthrax biomarker
A novel metal coordination polymer {[Zn2(L)(H2O)(DMA)]DMA·2.3H2O}n(1)has been isolated under solvothermal method,where L4-is the four-deprotonated N,N'-bis(4-carboxybenzyl)-5-aminoisophthalic acid and DMA is N,N-dimethylacetamide.Single crystal X-ray diffraction results showed that the complex belongs to the triclinic crystal system with the space group of P1,a=0.989 6(5)nm,b=1.370 5(5)nm,c=1.382 1(5)nm,α=80.067(5)°,β=76.729(5)°,γ=76.611(5)° and the structure of complex 1 is a 3D supramolecular framework that expanded by 2D metal-organic layers through π…π interactions.Interestingly,a"bowl"shaped structure exists in the 2D layer,and the center of the"bowl"is a cavity with a size of about 1.493 nm× 1.503 nm,which can be used to load a certain volume of guest molecules.Infrared spectroscopy verified the successful coordination of zinc ions with the L4-ligand.Powder X-ray diffraction(PXRD)experiments confirmed that complex 1 had high purity.Thermo-gravimetric analysis showed that complex 1 had good thermal stability in a range from room temperature to 416.9 C.Under the excitation light of 273 nm,complex 1 exhibited strong fluorescence emission at 437 nm in an ethanol solution,which could quickly detect the anthrax biomarker of pyridine-2,6-dicarboxylic acid(DPA)through fluores-cence quenching within 30 s.The results of concentration-dependent experiments showed that there was a good lin-ear relationship between the concentration of DPA and the fluorescence intensity of complex 1,with R2=0.996 51 and a quenching constant value of 4.052×104 L·mol-1.The calculated limit of detection was approximately 15 μmol L-1,which was significantly lower than the infection dose of anthrax spores(60 μmol·L-1).After adding various inter-ferents to the solution of complex 1,the change in fluorescence intensity of complex 1 was negligible.However,when DPA was added,the fluorescence intensity decreased significantly,indicating that complex 1 had a high selec-tivity for DPA.The detection mechanism was revealed by combining PXRD patterns and UV-Vis absorption spectra,which is fluorescence quenching induced by the collapse of the crystal framework.CCDC:2355003.
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