Systematic studies of hexanuclear {MIII4LnIII2} complexes (M = Fe, Ga; Ln = Er, Ho): structures, magnetic properties and SMM behavior

Four isostructural MIII4LnIII2 coordination clusters, [M4Ln2(μ3-OH)2(nbdea)4(C6H5COO)8]•MeCN (M = Fe, Ln = Er (1); M = Ga, Ln = Er (2); M = Fe, Ln = Ho (3); M = Ga, Ln = Ho (4)) have been synthesized and characterized. Single-crystal X-ray diffraction and X-ray powder diffraction studies revealed that all four compounds crystallize isomorphously to each other, and to the previously reported MIII4DyIII2 (M = Fe or Ga) and FeIII4YIII2 analogues. DC magnetic susceptibility measurements for compounds 1-4, taken in combination with those for the FeIII4YIII2 analogue, indicated that the interactions between ErIII ions are weakly ferromagnetic and the FeIII-ErIII interactions are very weakly antiferromagnetic, while the HoIII-HoIII and FeIII-HoIII interactions are both negligible. By comparison, for the FeIII4DyIII2 analogue, the DyIII-DyIII interactions are antiferromagnetic while the FeIII-DyIII are ferromagnetic. Both Er analogues 1 and 2 display single-molecule magnet (SMM) behavior with the effective energy barrier Ueff increasing from 12.8 K (for Fe4Er2 1) to 53.5 K (for Ga4Er2 2), indicating that the very weak 3d-4f interaction enhances the QTM effect

A single molecule magnet to single molecule magnet transformation via a solvothermal process: Fe₄Dy₂ →Fe₆Dy₃

Two series of heterometallic FeIII-LnIII compounds, [FeIII4LnIII2([small mu ]3-OH)2(mdea)4(m-NO2C6H4COO)8][middle dot]3MeCN where Ln = Y (1) and Dy (2) and [FeIII6LnIII3([small mu ]4-O)3([small mu ]3-O)(mdea)5(m-NO2C6H4COO)9][middle dot]3MeCN where Ln = Y (3) and Dy (4){,} were synthesized. Compounds 1 and 2 were obtained under ambient conditions{,} whereas 3 and 4 were obtained via a solvothermal transformation process by heating 1 or 2 at 120 [degree]C in MeCN. The magnetic properties of all four compounds have been measured and show that compounds 2 and 4 containing DyIII ions exhibit slow relaxation of magnetization characteristic of Single Molecule Magnetic (SMM) behaviour

Developing a "highway Code" to steer the structural and electronic properties of FeIII/DyIII coordination clusters

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Developing a “Highway Code” To Steer the Structural and Electronic Properties of Fe^III/Dy^III Coordination Clusters

In the recently established field of 3d/4f coordination cluster (CC) chemistry several burning questions still need to be addressed. It is clear that combining 3d and 4f metal ions within a coordination cluster core has the potential to lead to electronic structures that will be very difficult to describe but can also be extremely interesting. Furthermore, understanding why certain core topologies seem to be favored is difficult to predict. Here we show that the secondary coordination sphere provided by the ligands influences the favored product, as demonstrated for the compound [Fe₄Dy₂(μ₃-OH)₂(<i>n-</i>bdea)₄­(C₆H₅CO₂)₈]·MeCN (<b>1</b>), which has a 2Fe:2Dy:2Fe core and was made using [Fe^III₃O­(C₆H₅)­CO₂)­(L)₃]⁺ as starting material plus Dy­(NO₃)₃ and <i>N</i>-<i>n</i>-butyl-diethanolamine (<i>n-</i>bdeaH₂), compared with the compound made using a methyl meta-substituent (R) on the phenyl ring of the benzoate, [Fe^III₃O­(C₆H₄Me)­CO₂)­(L)₃]⁺ as starting material, which resulted in the “square-in-square” compound [Fe₄Dy₄(μ₃-OH)₄(<i>n-</i>bdea)₄­(O₂CC₆H₄CH₃)₁₂]·MeCN (<b>2</b>) when using ambient conditions. Changing reaction conditions from ambient to solvothermal leads to “double-propeller” compounds [Fe₄Dy₄(μ₄-O)₃(<i>n-</i>bdea)₃­(C₆H₅CO₂)₁₂]·13MeCN (<b>3</b>) and [Fe₄Dy₄(μ₄-O)₃(<i>n-</i>bdea)₃­(O₂CC₆H₄CH₃)₁₂]·MeCN (<b>4</b>) forming with this core, resulting irrespective of the substitution on the iron benzoate starting material. Furthermore, compounds <b>1</b> and <b>2</b> can be transformed into compounds <b>3</b> and <b>4</b>, respectively, using a solvothermal method. Thus, compounds <b>3</b> and <b>4</b> appear to be the thermodynamically most stable species. The factors steering the reactions toward these products are discussed. The electronic structures have been investigated using magnetic and Mössbauer studies. All compounds are cooperatively coupled 3d/4f systems, with compound <b>1</b> showing single-molecule magnet behavior

Regulatory volume decrease is actively modulated during the cell cycle

Nasopharyngeal carcinoma cells, CNE-2Z, when swollen by 47% hypotonic solution, exhibited a regulatory volume decrease (RVD). The RVD was inhibited by extracellular applications of the chloride channel blockers tamoxifen (30 μM; 61% inhibition), 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB, 100 μM; 60% inhibition), and ATP (10 mM; 91% inhibition). The level and time constant of RVD varied greatly between cells. Most cells conducted an incomplete RVD, but a few had the ability to recover their volume completely. There was no obvious correlation between cell volume and RVD capacity. Flow cytometric analysis showed that highly synchronous cells were obtained by the mitotic shake-off technique and that the cells progressed through the cell cycle synchronously when incubated in culture medium. Combined application of DNA synthesis inhibitors, thymidine and hydroxyurea arrested cells at the G1/S boundary and 87% of the cells reached S phase 4 h after being released. RVD capacity changed significantly during the cell cycle progression in cells synchronized by shake-off technique. RVD capacity being at its highest in G1 phase and lowest in S phase. The RVD capacity in G1 (shake-off cells sampled after 4 h of incubation), S (obtained by chemical arrest), and M cells (selected under microscope) was 73, 33, and 58%, respectively, and the time constants were 435, 769, and 2,000 sec, respectively. We conclude that RVD capacity is actively modulated in the cell cycle and RVD may play an important role in cell cycle progress

Suppression of ClC-3 channel expression reduces migration of nasopharyngeal carcinoma cells

Recent studies suggest that chloride (Cl−) channels regulate tumor cell migration. In this report, we have used antisense oligonucleotides specific for ClC-3, the most likely molecular candidate for the volume-activated Cl− channel, to investigate the role of ClC-3 in the migration of nasopharyngeal carcinoma cells (CNE-2Z) in vitro. We found that suppression of ClC-3 expression inhibited the migration of CNE-2Z cells in a concentration-dependent manner. Whole-cell patch-clamp recordings and image analysis further demonstrated that ClC-3 suppression inhibited the volume-activated Cl− current (ICl,vol) and regulatory volume decrease (RVD) of CNE-2Z cells. The expression of ClC-3 positively correlated with cell migration, ICl,vol and RVD. These results strongly suggest that ClC-3 is a component or regulator of the volume-activated Cl− channel. ClC-3 may regulate CNE-2Z cell migration by modulating cell volume. ClC-3 may be a new target for cancer therapies