Highly Specific Sulfadiazine Detection Using a Two-Dimensional Europium-Organic Coordination Polymer.

Sulfadiazine (SFZ) is an inexpensive large-consumption antibiotic used for treat bacterial infections but an excess of residues in food can be harmful. Fast and specific luminescence detection of SFZ is highly challenging because of the interference of structurally similar antibiotics. In this work, we develop a two-dimensional europium-organic coordination polymer with excellent luminescence and water stability for highly specific detection of SFZ in the range of 0-0.

Series of Benzoquinone-Bridged Dicobalt(II) Single-Molecule Magnets.

Mononuclear complexes within a particular coordination geometry have been well recognized for high-performance single-molecule magnets (SMMs), while the incorporation of such well-defined geometric ions into multinuclear complexes remains less explored. Using the rigid 2-(di(1-pyrazol-1-yl)methyl)-6-(1-pyrazol-1-yl)pyridine (PyPz) ligand, here, we prepared a series of benzoquinone-bridged dicobalt(II) SMMs [{(PyPz)Co}(L)][PF], (, L = 2,5-dioxo-1,4-benzoquinone (dhbq); , L = chloranilate (CA); and , L = bromanilate (BA)), in which each Co(II) center adopts a distorted trigonal prismatic (TPR) geometry and the distortion increases with the sizes of 3,6-substituent groups (H () < Cl () < Br ()). Accordingly, the magnetic study revealed that the axial anisotropy parameter () of the Co ions decreased from -78.

Slow magnetic relaxation in a Dy triangle and a bistriangular Dy cluster.

Two lanthanide single-molecule magnets (SMMs) [Dy(μ-OH)(HL-1)(HO)](NO)·3HO (1, HL-1 = ()-3-(((8-hydroxyquinolin-2-yl)methylene)amino)propane-1,2-diol) and [Dy(μ-OH)(HL-2)(HL-2)(L-2)] (2, HL-2 = ()-2-hydroxy-'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) were synthesized and characterized structurally and magnetically. Complex 1 contains a triangular Dy core in which the three Dy ions share a μ-OH anion and the deprotonated ligands of (HL-1) serve both capping and bridging functions, while 2 displays a centrosymmetric hexanuclear Dy structure with two similar Dy triangular cores ligated by two fully deprotonated (L-2) ligands, each of which shares two μ-OH anions. All the Dy ions are eight-coordinated with quasi or symmetry.

Self-assembly of Ni(II) metallacycles (a square and a triangle) supported by tetrazine radical bridges.

Two Ni(II) molecular metallacycles of [Ni(bpz*tz˙)(N)] (1) and [Ni(bpztz˙)(pz(Cl)tz˙)]·1.3CHOH·9.3HO (2) (bpz*tz = 3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine; bpztz = 3,6-bis(3-phenyl-pyrazolyl)-1,2,4,5-tetrazine; and pz(Cl)tz = 3-bis(3-phenyl-pyrazolyl)-6-Cl-1,2,4,5-tetrazine) are reported.

A Dicobalt(II) Single-Molecule Magnet via a Well-Designed Dual-Capping Tetrazine Radical Ligand.

The recent years have witnessed the glory development for the construction of high-performance mononuclear single molecule magnets (SMMs) within a specific coordination geometry, which, however, is not well applied in cluster-based SMMs due to the synthetic challenges. Given that the monocobalt(II) complexes within a trigonal-prismatic (TPR) coordination geometry have been classified as excellent SMMs with huge axial anisotropy ( ≈ -100 cm), here we designed and synthesized a new dual-capping tetrazine ligand, 3,6-bis(6-(di(1-pyrazol-1-yl)methyl)pyridin-2-yl)-1,2,4,5-tetrazine (bpptz), and prepared a novel dicobalt(II) complex, [CpCo][{(hfac)Co}(bpptz)][hfac]·2EtO (, hfac = hexafluoroacetylacetonate). In the structure of , the bpptz radical ligand enwraps two Co(II) centers within quasi-TPR geometries, which are further bridged by the tetrazine radical in the trans mode.

Incorporating Trigonal-Prismatic Cobalt(II) Blocks into an Exchange-Coupled [CoCu] System.

Taking advantage of a rigid tetradentate ligand of bis(pyrazoly)(3-pyrazolypyridinyl)methane (PyPz) and the [Cu(opba)] unit [opba = -phenylenebis(oxamato)], the trinuclear complex [{Co(PyPz)}Cu(opba)][ClO]·5MeCN·MeOH () was constructed, in which the Co centers adopt a trigonal-prismatic geometry, while considerable intramolecular magnetic coupling was successfully introduced through the oxamido bridges, representing another very first example of single-molecule magnets marrying both selected coordination geometry and magnetic exchanges.

Trigonal Prismatic Cobalt(II) Single-Ion Magnets: Manipulating the Magnetic Relaxation Through Symmetry Control.

Two mononuclear trigonal prismatic Co(II) complexes [Co(tppm*)][BPh] () and [Co(hpy)][BPh]·3CHCl () (tppm* = 6,6',6″-(methoxymethanetriyl)tris(2-(1-pyrazol-1-yl)pyridine; hpy = tris(2,2'-bipyrid-6-yl)methanol) were synthesized by incorporating the Co(II) ions in two pocketing tripodal hexadentate ligands. Magnetic studies indicate similar uniaxial magnetic anisotropy while having distinct dynamic magnetic properties for two complexes, of which exhibits clear hysteresis loops and Orbach process governed magnetic relaxation with an effective energy barrier () of 192 cm, among the best examples in transition metallic SIMs, about 10 times larger than that of ( = 20 cm, extracted by fitting the data to an Orbach relaxation process but there is no real state at this energy). Such pronounced difference is ascribed to the dominant Raman process and quantum tunneling of magnetization (QTM) in owing to the structural distortion and symmetry breaking, indicated by a nearly perfect trigonal prismatic geometry ( local symmetry) for and a more distorted configuration for ( local symmetry).

Synthesis and magnetic studies of pentagonal bipyramidal metal complexes of Fe, Co and Ni.

Three mononuclear metal complexes [MII(L-N3O2)(MeCN)2][BPh4]2 (M = Fe, 1; Co, 2; Ni, 3) were isolated and structurally characterized. Magnetic studies revealed uniaxial magnetic anisotropy for 1 (D = -17.1 cm-1) and 3 (D = -14.

Construction and Magnetic Study of a Trigonal-Prismatic Cobalt(II) Single-Ion Magnet.

A new tripodal hexadentate ligand of tris[6-(1 H-pyrazol-1-yl)pyridin-2-yl]methanol (tppm) was synthesized and explored for constructing the trigonal-prismatic cobalt(II) complex [Co(tppm)][ClO]·2CHCN·HO (1). Magnetic study showed that 1 exhibited large uniaxial magnetic anisotropy with a zero-field-splitting parameter of -80.7 cm and typical single-molecule-magnet behavior.