A micrometer-sized europium(iii)-organic framework for selective sensing of the Cr2O72- anion and picric acid in water systems.

A micrometer-sized europium(iii)-organic framework with asymmetric binuclear metal subunits extended by 4,5-dichlorophthalaten (DCPA), [Eu2(H2O)(DCPA)3]n, was easily obtained using a reverse microemulsion method. The framework exhibits good dispersibility, excellent thermal and environmental stability and easy regeneration ability. More importantly, the complex displays strong red emission and can selectively and sensitively detect both inorganic Cr2O72- anions (Ksv = 8.7 × 103 M-1) and organic picric acid contaminants (Ksv = 1.07 × 104 M-1) in water systems through fluorescence quenching. A luminescent film of 1 was further prepared and successfully used to detect the Cr2O72- anion in an aqueous system. These interesting results indicate that the well-dispersed europium(iii)-organic framework can serve as a promising dual-responsive luminescent sensor for environmental pollutant monitoring.

Four linear Cu(II)3 subunit-based coordination polymers with various inter-subunit connections, spin ground-states and intra-/inter-subunit magnetic couplings.

Four new 4-amino-1,2,4-triazole (atr)-based coordination polymers, {[Cu2(atr)(H2O)(µ-OH)2(pa)]·H2O}n (), {[Cu3(atr)2(H2O)2(µ-OH)2(npa)2]·2H2O}n (), {[Cu3(atr)5(dca)(µ-OH)(ClO4)2](ClO4)2}n () and {[Cu3(atr)2(H2O)(µ3-OH)(µ-OH)2(spa)]·1.5H2O}n () (pa(2-) = phthalate, npa(2-) = 3-nitrophthalate, dca(-) = dicyanamide and spa(3-) = 4-sulfophthalate), were successfully obtained by varying the carboxylate- and cyanide-modified magnetic bridges. Structural determinations reveal that the former three samples are bent one-dimensional chains constructed from linear Cu(II)3 subunits and different inter-subunit connections. In , linear {Cu3(µ-N1,N2-atr)2(µ-OH)2}(4+) and {Cu3(µ-COO)2(µ-OH)2}(4+) subunits are alternately connected in a sharing-vertex manner to give a ferrimagnetic S = 1/2 spin ground-state. The linear {Cu3(µ-N1,N2-atr)2(µ-OH)2}(4+) building block of is repeatedly bridged by pairs of single-atom bridging carboxylate groups of the npa(2-) ligand leading to a paramagnetic S = 1/2 spin ground-state. By contrast, each linear {Cu3(µ-N1,N2-atr)4}(6+) core in is periodically propagated by four-fold heterobridges (µ-OH(-), µ-ClO4(-), µ-N1,N2-atr and µ-dca(-)) to generate an overall diamagnetic S = 0 spin ground-state. Complex is a three-dimensional pillared-layer framework composed of linear {Cu3(µ-N1,N2-atr)2(µ-OH)2}(4+)-based layers and ditopic spa(3-) connectors, which exhibits a ferrimagnetic S = 1/2 spin ground-state and a metamagnetic transition resulting from the competition between the weak interchain/interlayer antiferromagnetic interaction and the enhanced external magnetic field. In addition, different intra- and inter-subunit magnetic strengths are observed in with the coupling constants 182 < -Jintra < 43 and -127 < Jinter < 51.2 cm(-1). These interesting magnetostructural results are significant and helpful for the cyclic polyazolate-based magnetic materials.