Ligand Field Affected Single-Molecule Magnet Behavior of Lanthanide(III) Dinuclear Complexes with an 8-Hydroxyquinoline Schiff Base Derivative as Bridging Ligand.

New dinuclear lanthanide(III) complexes based on an 8-hydroxyquinoline Schiff base derivative and ß-diketonate ligands, [Ln2(hfac)4(L)2] (Ln(III) = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)), [Ln2(tfac)4(L)2] (Ln(III) = Gd (6), Tb (7), Dy (8), Ho (9)), and [Dy(bfac)4(L)2·C7H16] (10) (L = 2-[[(4-fluorophenyl)imino] methyl]-8-hydroxyquinoline, hfac = hexafluoroacetylacetonate, tfac = trifluoroacetylacetonate, and bfac = benzoyltrifluoroacetone), have been synthesized. The single-crystal X-ray diffraction data show that complexes 1-10 are phenoxo-O-bridged dinuclear complexes; each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate ß-diketonate coligands and two µ2-O bridging 8-hydroxyquinoline Schiff base derivative ligands. The magnetic study reveals that 1 and 6 display cryogenic magnetic refrigeration properties, whereas complexes 3, 8, and 10 show different SMM behaviors with energy barriers of 6.77 K for 3, 19.83 K for 8, and 25.65 K for 10. Meanwhile, slow magnetic relaxation was observed in 7, while no out-of-phase alternating-current signals were found for 2. The different dynamic magnetic behaviors of two Tb2 complexes and the three Dy2 complexes mainly derive from the tiny crystal structure changes around the Ln(III) ions. It is also proved that the ß-diketonate coligands can play an important role in modulating magnetic dynamics of the lanthanide 8-hydroxyquinoline Schiff base derivative system.

Hepatic inflammatory pseudotumor mimicking malignancy: the value of differential diagnosis on contrast enhanced ultrasound.

The aim of this study is to investigate whether the use of contrast enhanced ultrasound (CEUS) can improve the differential diagnostic performance between hepatic inflammatory pseudotumor (HIPT) and other malignant tumors. MATERIAL AND METHODS: Forty-four patients with histological proven HIPTs were included in this retrospective study. The features of conventional ultrasound (US) and CEUS were evaluated. RESULTS: Three kinds of enhanced pattern can be seen in the 44 nodules including homogeneous (n=18, 41%), heterogeneous (n=16, 36%) and rim-like enhancement (n=10, 23%). All of the nodules showed hypo-enhancement during the portal and delayed phase. The dominant nodules (n=29, 66%) presented wash-out within 60 s after contrast injection. Quick wash-in and wash-out was seen in 18 nodules (41%). Eighteen nodules (41%) were correctly diagnosed as HIPT, whereas the remaining 26 cases were misdiagnosed as malignancies (n=20, 45%) or with an uncertain diagnosis (n=6, 14%). CONCLUSION: CEUS was not enough to differentiate HIPT from hepatic malignancies, especially intrahepatic cholangiocarcinoma and liver metastasis. However, some CEUS imaging characteristics may be helpful for HIPT diagnosis.

CO Adsorption on Metal-Decorated Phosphorene.

Using first principle calculations, we have investigated the adsorption of CO gas on various metal-decorated phosphorene. Almost all of the metals were considered to decorate phosphorene. By comparing binding energy (E b) and cohesive energy (E c), only 10 metals (Li, Na, K, Rb, Cs, Ca, Sr, Ba, Pd, and La) can stably decorate phosphorene and avoid clustering. CO adsorptions on these metal-decorated systems were calculated, and the mechanism of interaction between CO and metal atoms was analyzed in detail. E a shows a significant improvement after metal decoration, excerpt for Rb and Cs. The results imply that Li-, Na-, K-, Ca-, Sr-, Ba-, and La-decorated phosphorene could be used as CO elimination or reversible CO storage.

Enhancing the ambient stability of few-layer black phosphorus by surface modification.

Based on high-throughput density functional theory calculations, we investigated the adsorption characteristics of various elements across the Periodic Table on few-layer black phosphorus (BP). Using the criterion that the ratio of adsorption energy (E ads) to bulk cohesive energy (E coh) is greater than one (E ads/E coh > 1), we selected fifteen elements. The adsorption of these elements on few-layer BPs could significantly shift their conduction-band minimum (CBM) downward, suggesting the possibility of preventing the few-layer BPs from oxidation if the CBM can be shifted below the O2/O2 - redox potential. Our study offers an efficient approach to overcoming the technical barrier in the practical application of few-layer BPs by enhancing its ambient stability via surface modification.

A Dy4 single-molecule magnet and its Gd(iii), Tb(iii), Ho(iii), and Er(iii) analogues encapsulated by an 8-hydroxyquinoline Schiff base derivative and ß-diketonate coligand.

Five new tetranuclear complexes based on an 8-hydroxyquinoline Schiff base derivative and the ß-diketone coligand, [Ln4(acac)4L6(µ3-OH)2]·CH3CN·0.5CH2Cl2 (Ln = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5); HL = 5-(benzylidene)amino-8-hydroxyquinoline; acac = acetylacetonate) have been synthesized, and structurally and magnetically characterized. Complexes 1-5 have similar tetranuclear structures. Each LnIII ion is eight coordinated and its coordination polyhedra can be described as being in a distorted square-antiprismatic geometry. The magnetic studies reveal that 1 features the magnetocaloric effect (MCE) with the magnetic entropy change of -ΔSm(T) = 25.08 J kg-1 K-1 at 2 K for ΔH = 7 T, and 3 displays the slow magnetic relaxation behavior of Single Molecule Magnets (SMMs) with the anisotropic barrier of 86.20 K and the pre-exponential factor τ0 = 2.99 × 10-8 s.

Multiple magnetic relaxation processes, magnetocaloric effect and fluorescence properties of rhombus-shaped tetranuclear rare earth complexes.

Seven new tetranuclear rare earth (RE) complexes [RE4(acac)4L6(µ3-OH)2] (HL = 5-(4-fluorobenzylidene)-8-hydroxylquinoline; acac = acetylacetonate; RE = Y (1), Eu (2), Gd (3), Tb (4), Dy (5), Tm (6) and Lu (7)) have been synthesized and completely characterized. Complex exhibits multiple zero-field slow magnetic relaxation processes typical of Single Molecule Magnets (SMMs). Two distinct slow magnetic relaxation processes, with effective energy barriers of Ueff = 48 K for the slow relaxation (SR) process and Ueff = 121 K for the fast relaxation (FR) process, are mainly attributed to the presence of two crystallographically independent Dy(III) sites. The magnetocaloric effect (MCE) was detected as -ΔSm(T) = 20.8 J kg(-1) K(-1) for complex . The fluorescence properties of complexes 1, 2, 4, 5 and 7 were also investigated. Complexes 2, 4 and 5 show the characteristic peaks for their corresponding RE(III) center, while complexes 1 and 7 show similar emission peaks to the Schiff base ligand when they are excited at the appropriate wavelength.

Modulation of the relaxation dynamics of linear-shaped tetranuclear rare-earth clusters through utilizing different solvents.

Nine new tetranuclear centrosymmetric linear complexes, [RE4(dbm)8L2(DMF)2]·nCH2Cl2·mC2H3N (RE = Y (1), Tb (2), Dy (3), Ho (4), Er (5), Lu (6)) and [RE4(dbm)8L2(C2H5OH)2]·nCH3CN (RE = Tb (7), Dy (8), Ho (9)) (HL = 2-[(2-(hydroxyimino)propanehydrazide)methyl]-8-hydroxyquinoline and dbm = 1,3-diphenyl-1,3-propanedione) have been synthesized. Complexes 1-9 are tetranuclear complexes. Magnetic studies reveal that both DyIII-based complexes (3 and 8) exhibit single-molecule magnet (SMM) behavior under a zero dc field. Furthermore, complex 3 presents one relaxation process under a zero dc field, while application of an external dc field (1500 Oe) induces multi-relaxation signals of the ac magnetic susceptibility.

Seven phenoxido-bridged complexes encapsulated by 8-hydroxyquinoline Schiff base derivatives and ß-diketone ligands: single-molecule magnet, magnetic refrigeration and luminescence properties.

Seven dinuclear complexes based on 8-hydroxyquinoline Schiff base derivatives and ß-diketone ligands, [RE2(hfac)4L2] (RE = Y (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6) and Lu (7); hfac(-) = hexafluoroacetylacetonate; HL = 2-[(4-chloro-phenylimino)-methyl]-8-hydroxyquinoline), have been synthesized, and structurally and magnetically characterized. Complexes 1-7 have similar dinuclear structures, in which each RE(III) ion is eight coordinated by two L(-) and two hfac(-) ligands in a distorted dodecahedron geometry. The luminescence spectra indicate that complex 3 exhibits characteristic Tb(III) ion luminescence, while 1 and 7 show HL ligand luminescence. The magnetic studies reveal that 2 features a magnetocaloric effect with the magnetic entropy change of -ΔSm = 16.83 J kg(-1) K(-1) at 2 K for ΔH = 8 T, and 4 displays slow magnetic relaxation behavior with the anisotropic barrier of 6.7 K and pre-exponential factor τ0 = 5.3 × 10(-6) s.

Luminescence, magnetocaloric effect and single-molecule magnet behavior in lanthanide complexes based on a tridentate ligand derived from 8-hydroxyquinoline.

A new family of lanthanide complexes, [Ln2(hfac)4L2] (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Lu (7); hfac = hexafluoroacetylacetonate, HL = 2-(2'-benzothiazole)-8-hydroxyquinoline), was synthesized and characterized using single-crystal X-ray diffraction, elemental analysis (EA), thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD) and UV-vis spectra. X-ray crystallographic analyses reveal that 1­7 are isomorphous and crystallize in the monoclinic space group C2/c. In these dinuclear complexes, each LnШ ion is eight-coordinated with two bidentate hfac and two µ-phenol bridging L ligands. The TGA results show that the complexes have relatively high thermal stabilities. Complexes 1 and 3 show the characteristic transitions of the corresponding lanthanide ions with ligand-related emission peaks. Meanwhile, complexes 4 and 7 exhibit ligand-centered fluorescence at room temperature. Magnetic measurements were carried out on complexes 2­6. The magnetic study reveals that 2 displays a magnetocaloric effect, with a maximum −ΔSm value of 16.89 J K−1 kg−1 at 2 K for ΔH = 8 T. Dynamic magnetic studies reveal single-molecule magnet (SMM) behavior for complex 4. Fitting the dynamic magnetic data to the Arrhenius law gives an energy barrier ΔE/kB = 50.33 K and pre-exponential factor τ0 = 1.05 × 10(-8)s.