A 1D brick-like coordination polymer containing free-standing sulfonic units for luminescence sensing of uranium in aqueous solution

Abstract

A novel brick-like 1D coordination polymer of Zn2(H2O)2(H2L) (BDC-SO3)2·5H2O (namely ECUT-135, L ​= ​4,4’-(3,4-bis(4-((E)-2-(pyridin-4-yl)vinyl)phenyl)cyclobutane-1,2-diyl) dipyridine, H2BDC-HSO3 ​= ​5-sulfoisophthalic acid) was synthesized with Zn(NO3)2, 1,4-bpeb (1,4-bis((E)-2- (pyridin-4-yl)vinyl)benzene) and H2BDC-HSO3. Interestingly, the resulted structure contains the in-situ formation ligand of H2L through [2 ​+ ​2] cyclization. In the 3D stacking structure abundant free-standing –SO3 units were observed. The solid of ECUT-135 was found to give strong blue emission, and further enables luminescence sensing of uranium in aqueous solution, giving a detection limit of 20.45 ​nM/L for uranyl ions, far below the standard of <130 ​nM for uranium in drinking water requested by the United States Environmental Protection Agency.