A luminescent Cd(II) coordination polymer as a fluorescence-responsive sensor for enhancement sensing of Al3+ and Cr3+ ions and quenching detection of chromium(VI) oxyanions

Abstract A luminescent coordination polymer [Cd(H2dhbdc)(NI-mbpy-34)2]n (1), where H4dhbdc ​= ​2,5-dihydroxyterephthalic acid, NI-mbpy-34 ​= ​N-(pyridin-3-ylmethyl)-4-(pyridin-4-yl)-1,8-naphthalimide, has been synthesized under hydro(solvo)thermal conditions. From the topological point of view, the crystal structure of 1 is fabricated by 4-connected square-planar nodes, forming a complicated two-dimensional (2-D) gridlike sql layer with the point symbol of (44·62), which consists of one-dimensional (1-D) {Cd–NI-mbpy-34}n2n ​+ ​ribbon chains and H2dhbdc2− bridges. Complex 1 displays high thermal, chemical, and pH stabilities. Moreover, complex 1 exhibits pH- and solvent-dependent luminescence properties varying in intensity and wavelength, and emits blue fluorescence in H2O suspension phase. These features promise 1 to be a multifunctional sensor platform for sensitive detection of Al3+ and Cr3+ through luminescence enhancement as well as CrO42− and Cr2O72− through luminescence quenching from most interfering ions.