Search

By using 2, 2'-biimidazole (2, 2′-biim) and 2, 2′-bipyridine (2, 2′-bipy) as structure-directing agents (SDAs), two cadmium diphosphonates, [Cd2(H2L)2(H2O)] (1) and [Cd5(HL)2(H2L)2]·4H2O (2) (H4L = 4–F–C6H4CH2N(CH2PO3H2)2), have been hydrothermally synthesized. The introduction of different N-heterocyclic aromatic SDAs results in the diverse structures, thermal stabilities, and luminescent properties. Structural analyses reveal that both 1 and 2 show three-dimensional (3D) supramolecular structures wherein the adjacent layers are further connected by moderately π–π stacking interactions or hydrogen-bond interactions. Among them, the thermal stability of 1 is higher than 2. Surprisingly, 1 displays excellent luminescent performance, whereas 2 shows no luminescent signal. Based on the intense luminescence of 1, it can serve as a high selectively and sensitively luminescent sensor for Hg2+ with a low detection limit of 3.1 × 10–7 M in aqueous solution. Additionally, the probable sensing mechanism for 1 has also been investigated in detail, which can be assigned to the weak interaction between the uncoordinated O sites from the H2L2– ligands and Hg2+. Two cadmium diphosphonates with different structures and luminescent properties have been hydrothermally obtained by using N–heterocyclic aromatic (2, 2′–biim and 2, 2′‒bipy) compounds as SDAs. 1 displays excellent luminescent performance, whereas 2 shows no luminescent signal. Furthermore, 1 can serve as a luminescent sensor for Hg2+ in water [ABSTRACT FROM AUTHOR]

Two tetra-nuclear Yb III -incorporated selenotungstate clusters, Keggin (C 2 H 8 N) 6 Na 14 [Yb 4 Se 6 W 44 O 160 (H 2 O) 12 ]·40H 2 O (1) and Wells-Dawson (C 2 H 8 N) 4 Na 14 [Yb 4 Se 6 W 45 O 159 (OH) 6 (H 2 O) 11 ]·38H 2 O (2), have been isolated through a pH-controlled assembly, which exhibit the first Yb III -containing polyoxotungstates with selenium heteroatoms. Their assemblies rely on the structure-directing effects of SeO 3 2- anion templates to give rise to available Se-containing Keggin-/Wells-Dawson-type motifs. Both compounds were characterized by single-crystal X-ray diffraction, IR spectroscopy, power X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) as well as electrospray ionization mass spectrometry (ESI-MS). Furthermore, systematic magnetic studies revealed that 1 exhibits field-induced single-molecule magnetic behavior with a pre-exponential factor of τ 0 = 6.60(7) × 10 -8 s and a relaxation energy barrier of ΔE/k B = 39.44(2) K, while 2 only displays antiferromagnetic interactions between the ytterbium centers.