Two alkaline earth metal coordination polymers based on a new oxamate-dicarboxylate ligand: Selective fluorescence sensing of Fe3+ in aqueous solution.

Two different alkaline earth metal coordination polymers (AE-CPs) {[Ca 3 L 2 (H 2 O) 6 ]·2H 2 O} n (1) and [Sr(H 2 L) 2 ] n (2) were constructed from using 5-(ethyl oxamate)-isophthalic acid (H 2 EtL) ligand with alkaline earth metal ions Ca2+ and Sr2+ under solvothermal conditions, respectively. Among them, L and H 2 L are formed by in-situ hydrolysis of H 2 EtL, which display multiple kinds of coordinated modes through oxamate and carboxylate groups. 1 and 2 both show three-dimensional coordination frameworks possessing unprecedented (3,4,5)-connected skg1 topology and (3,6)-connected ant topology, respectively. The solid-state fluorescence properties of 1 and 2 were studied, and 1 with bright blue luminescence reveals selective sensing toward Fe3+ ion in water with the low detection limit (LOD) of 1.04 × 10−3 M. Two new AE-CPs were constructed from a new oxamate-dicarboxylic ligand, revealing novel 3D frameworks and strong luminescent properties. In addition, 1 shows fluorescent sensing toward Fe3+ ion in water with good sensitivity and recyclability. Unlabelled Image • Two novel coordination polymers based on alkaline earth metal ions and a new oxamate-dicarboxylate ligand. • Two coordination polymers reveal diverse topologies due to different coordinated modes of ligands. • Ca-complex shows selective luminescence sensing toward Fe3+ ion in water. [ABSTRACT FROM AUTHOR]