Cluster-based CaII, MgII and CdII coordination polymers based on amino-functionalized tri-phenyl tetra-carboxylate: Bi-functional photo-luminescent sensing for Fe3+ and antibiotics

Abstract Excess and deficiency of iron(III) and antibiotics from normal permissible limits will induce serious disorders, so their detection is important but challenging. In this work, the asymmetric amino-functionalized tetra-carboxylate H 4 L (2′-amino-1,1’:4′,1″-terphenyl-3,3″,5,5″-tetracarboxylic acid) containing large conjugated ter-phenyl aromatic backbones have been synthesized and employed. Through a one-pot powerful solvo-thermal synthetic strategy, a series of unique tri-nuclear cluster-based Ca II , Mg II and Cd II coordination polymers, namely [Ca 1.5 ( μ 8 -HL)(DMF)] n ( 1 ), {[Mg 1.5 ( μ 7 -HL)·(H 2 O) 2 ]·3H 2 O} n ( 2 ) and {[Cd 1.5 ( μ 10 -L) 0.75 ] n ·H 2 O·DMF} n ( 3 ) have been successfully prepared. 1 – 3 exhibit excellent photo-luminescent properties and good fluorescence stability. Structural analyses reveal that tri-nuclear Ca II secondary building blocks (SBUS) are linked via HL 3− , forming the 2D clustered-based micro-porous coordination polymer 1 . As for 2, three carboxylate groups of partly de-pronated HL 3− also link these neighboring tri-nuclear Mg II SBUS, which constructs the 2D Mg II coordination framework 2 . As for 3 , fully de-pronated L 4− also links these neighboring tri-nuclear Cd II SBUS, which ultimately constructs the 3D micro-porous coordination framework 3. Experimental powder x-ray diffraction (PXRD) patterns coincide well with the theoretical patterns, which indicate that we have successfully synthesized the pure phase material 1 – 3 . Photo-luminescent experiments demonstrate that coordination polymers 1 – 3 can be successfully applied towards bi-functional sensing for sensitive detection of Fe 3+ and the antibiotics NZF (Nitrofurazone). To the best of our knowledge, this is the first example of the application of amino-functionalized tri-phenyl tetra-carboxylate based MOFs towards bi-functional discrimination of Fe 3+ and NZF antibiotics with high efficiency K sv values (For Fe 3+ : 7.28 × 10 4  M −1 for 1 ; 3.38 × 10 4  M −1 for 2 and 3.29 × 10 4  M −1 for 3 and for NZF antibiotics: 4.47 × 10 3  M −1 for 1 ; 4 × 10 3  M −1 for 2 and 5.6 × 10 3  M −1 for 3 ).