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External stimuli-responsive phase transition of metal-organic frameworks (MOFs) introduces intriguing functions for diverse applications under practical settings. Herein, we reported a phase transition from cubic Ce-UiO-66 to triclinic Ce-BDC-OH under light irradiation. Such a phase transition underwent a ligand-to-metal charge transfer process, which was unambiguously revealed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, electron paramagnetic resonance, etc. We proposed a phase transition mechanism through (1) the photoreduction of the metal core from Ce

The title compound was studied, which showed relatively large rhombic anisotropy and field-induced slow magnetic relaxation behaviour.

A family of fully sandwiched arachno-lanthanacarborane complexes formulated as {6-[µ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10]2Ln}{Li5(THF)10} (Ln = Tb, Dy, Ho, Er, Y) is successfully synthesized, where the “carbons-adjacent” carboranyl ligand (arachno-C2B10H104−) bears four negative charges and coordinates to the central lanthanide ions using the hexagonal 6­C2B4 face. Thus, the central lanthanide cations are pseudo-twelve-coordinate and have an approximate local D6h symmetry or hexagonal-prismatic geometry. As the crystal field effect imparted by this geometry is still unknown, we thoroughly investigated the magnetic properties of this series of complexes and found the crystal field imposed by this ligand causes a relation of Tb > Dy > Ho > Er for the energy gaps between the ground and the first excited states, which is of striking resemblance to the ferrocenophane and phthalocyanine ligands despite that the latter two ligands give disparate local coordination geometries. Moreover, the effective energy barrier to magnetization reversal of 445(10) K, observable hysteresis loop up to 4K and the relaxation time of the yttrium diluted sample reaching 193(17) seconds at 2 K under an optimized field for the Tb analogue of this family of arachno-lanthanacarborane complexes, render a new benchmark for Tb3+ based single-molecule magnets.

Engineering the local dynamic environment is currently the major approach for preventing fast magnetization loss for single-molecule magnets (SMMs). It is hypothesized that the presence of fewer −CH3 which results in fewer C−H bonds, would reduce excitation energy loss via vibrations, but thus far, no experimental evidence clearly elaborates this effect. Moreover, although Gu and Wu proposed a vibronic barrier model to interpret the Raman process, the relationship between the barriers (\hbar\omega) and the molecular structure has not been explicitly correlated. Here, we use the trifluoromethyl group to systematically substitute the methyl groups in the axial position of the parental bis-butoxide pentagonal-bipyramidal dysprosium(III) SMM - [Dy(OtBu)2(py)5][BPh4]. The resulting complexes - [Dy(OLA)2py5][BPh4] (LA = CH(CF3)2− 1, CH2CF3− 2, CMe2CF3− 3)- show progressively enhanced TBhys (@100 Oe/s) from 17 K (for 3), 20 K (for 2) to 23 K (for 1). As the gradually enhanced averaged vibration energy generated by different axial ligands from 230 cm−1 (for 3), 257 cm−1 (for 2) to 321 cm−1 (for 1) was identified experimentally and theoretically to be the only variant that leads to this improvement, this finding unambiguously reveals, for the first time, the correlation between structural change and the multi two-phonon (Raman) relaxation processes in lanthanide-based SMMs and highlights the importance of controlling the relevant vibrations in building SMMs with higher blocking temperatures.

A range of pyrazolate-based ligands have been used to balance the multidentate-chelating feature and the magnetic axiality in “destroyed” pentagonal-bipyramidal (DPB) dysprosium(III) single-molecule magnets (SMMs). This family of complexes are air-stable and share the general formulae of [DyX1X2(Leq)5][BPh4], where X1 and X2 are the anionic axial ligands, including pyrazolate-based ligands and chloride; Leq is the equatorial solvent molecule such as tetrahydrofuran (THF), pyridine (py) and thiazole (NS). Compared to the prototype PB SMMs, the bidentate-chelating features of the pyrazolate ligands show, albeit slow magnetic relaxation behavior, a much smaller energy barrier for magnetization reversal (Ueff). Static electronic calculation shows that the magnetic axiality above the ground mJ = ±15/2 states has been much reduced, leading to the mixing of other states at higher levels. Nevertheless, this systematic study reveals that the variation of the substituents on the pyrazolate ligands and the replacement of planar solvents are effective at influencing the magnetic relaxation behavior. We found that the chloride coordinating mono-pyrazolate complexes, such as [DyX1Cl(THF)5][BPh4] (X1 = 3-(trifluoromethyl)pyrazole (tfpz) 1, X1 = 3-methylpyrazole (Mepz) 2, X1 = 3-isopropyl-1H-pyrazole (Iprpz) 3, X1 = 3,5-dimethylpyrazole (Me2pz) 4, X1 = 3,5-diisopropylpyrazole (Ipr2pz) 5, and X1 = pyrazole (pz) 6, generally show lower Ueff, while bi-pyrazolate complexes, such as [Dy(tfpz)2(THF)5][BPh4] 7, [Dy(pz)2(THF)5][BPh4] 8, [Dy(pz)2(py)5][BPh4]·2py 9 and [Dy(pz)2(NS)5][BPh4] 10, show higher Ueff. Among them, 8 shows the largest Ueff of 521(8) K and a comparable open hysteresis temperature of ∼5 K (at a field sweeping rate of 12 Oe s−1) with 9 and 10. The enhanced blocking temperature for 8 is different from that for the PB Dy(III) SMMs in which the py ligand can cause a much higher hysteresis temperature than the one coordinated with THF due to the aromatic π–π interactions, indicating that the bis-bidentate-chelating Dy(III) ion is rigid enough to reduce the influence from the equatorial ligands. Moreover, substitution with electron-withdrawing groups such as the −CF3 group reduces Ueff prominently. Such a clear magnetostructural correlation in Dy(III) SMMs is fundamentally important, indicating that a subtle balance between magnetic axiality and molecular rigidity is critical to design high-performance Dy(III) SMMs.

Although single-molecule magnets (SMMs) have been considered as the smallest entity to store binary information, the ability to retain the magnetization in one direction for more than 100 seconds is still below liquid nitrogen boiling point (77 K). One of the effective ways to enhance the magnetic blocking temperature is to couple the anisotropic magnetic centers in a proper manner. However, this has been only succeeded in the radical-bridged SMMs so far. For non-radical bridges the 100-second blocking temperature is still not seen. Here we report the best non-radical bridged dimeric SMM - {[Dy(OtBu)(4-NH2py)5]2(µ-Cl)}[BPh4]3 1 - with an energy barrier to magnetization reversal of 1302(6) K and 100-second blocking temperature near 8 K. Compared to the similar local C5v symmetric mononuclear complex [Dy(OtBu)Cl(py)5]BPh4 2, the much higher performance of dimeric 1 is attributed to the pseudo-D5h symmetry and "head-to-tail" linked Dy(III) principle magnetic via the collinear Dy‒Cl‒Dy exchange-coupling pathway.

Molecules with long preserved magnetic moments are perceived as the smallest units for storing bytes, which could bring a new revolution for information technology. However, the rational design of such molecules remains challenging. Here we show it is possible to predesign such molecules by studying the vibration spectra. Two adamantanol based dysprosium(III) complexes with pentagonal-bipyramidal local geometry were theoretically predicted to display enhanced single-molecule magnet (SMM) behavior due to the reduced vibration modes in low energy regimes. The experimental isolation of these two complexes not only confirms this prediction, but further reveals almost unchanged large energy barriers and high blocking temperatures in solution state. This is never observed in previous studies of SMMs, indicating that the adamantanol ligand is rigid enough to make the complexes exhibiting intrinsic magnetic property in solution. As vibration spectrometer is routinely accessible in common laboratories this work provides a facile strategy to construct high-performance SMMs.

Summary Ten lanthanacarborane complexes were synthesized to study the rare B−Hδ−∙∙∙Mn+ inverse hydrogen bonds (IHBs). The average bonding energy of B−Hδ−∙∙∙Ln3+ is theoretically determined to be larger than 24 kJ/mol, which is comparable to moderately strong hydrogen bonds (21–56 kJ/mol). In addition to NMR and IR, magnetometer was used to study the exchange-coupling interaction via such B−Hδ−∙∙∙Ln3+ IHBs in detail, and the coupling constant is determined to be −2.0 cm−1, which is strong enough to compare with single-atom bridged dysprosium(III) complexes. Two imidazolin-iminato incorporated complexes have shown energy barrier for magnetization reversal larger than 1000 K, and the exchange-biasing effects are evident. Moreover, the bonding strengths of B−Hδ−∙∙∙Mn+ IHBs are cation-dependent. If M = Na, the B−Hδ−∙∙∙Na+ bonding energy is reduced to 14 kJ/mol, and the dimerization process is no longer reversible. The exchange-biasing effect is also disappeared. We believe such a finding extends our knowledge of IHBs., Graphical abstract, Highlights • Cation-dependent inverse hydrogen bonds are found in lanthanacarborane complexes • The lanthanacarborane dimeric assembly via inverse hydrogen bonds is reversible • The average bonding energy of B−Hδ−∙∙∙Ln3+ is larger than 24 kJ/mol • Inverse hydrogen bonded dysprosiacarborane dimers are single-molecule magnets, Chemistry; Inorganic chemistry; Molecular inorganic chemistry; Magnetism.

To investigate the feasibility of transfection of recombinant human endothelial nitric oxide synthase (eNOS) into human hypertrophic scar fibroblasts (HSFbs), and to observe NO secretion and the synthesis of collagen I and III.Recombinant human eNOS with karyocyte expressive vector was constructed in vitro, then was transfected into HSFbs which was isolated from hypertrophic scar tissues and cultured in vitro (T group). The HSFbs untransfected (normal culture) or transfected with empty-vector was used as control group and empty-vector group respectively. The mRNA expression of eNOS, collagen I and III was determined by Realtime PCR. The content of NO was determined by NO assay kit.The expression of eNOS mRNA in T group was 5.92 +/- 0.21, which was obviously higher than that in empty-vector group (0.98 +/- 0.13, P0.05). The expression of collagen I mRNA (0.76 +/- 0.15), and collagen III (0.79 +/- 0.08) in T group was significantly lower than those in empty-vector group (0.98 +/- 0.15, 1.02 +/- 0.12, P0.05, respectively). The content of NO in T group (36.1 +/- 0.8 micromol/L) was obviously higher than that in empty-vector group (28.4 +/- 1.0 micromol/L, P0.01) and control group (27.7 +/- 1.3 micromol/L, P0.01).HSFbs can be the target cells for eNOS gene transfection. The transfected cells can express eNOS and produce NO, which inhibit the synthesis of collagen.