Substituent Positioning Effects on the Magnetic Properties of Sandwich-Type Erbium(III) Complexes with Bis(trimethylsilyl)-Substituted Cyclooctatetraenyl Ligands.

Lanthanide complexes with judiciously designed ligands have been extensively studied for their potential applications as single-molecule magnets. With the influence of ligands on their magnetic properties generally established, recent research has unearthed certain effects inherent to site differentiation due to the different types and varying numbers of substituents on the same ligand platform. Using two new sandwich-type Er(III) complexes with cyclooctatetraenyl (COT) ligands featuring two differently positioned trimethylsilyl (TMS) substituents, namely, [Li(DME)Er(COT1,5-TMS2)2]n (Er1) and [Na(DME)3][Er(COT1,3-TMS2)2] (Er2) [COT1,3-TMS2 and COT1,5-TMS2 donate 1,3- and 1,5-bis(trimethylsilyl)-substituted cyclooctatetraenyl ligands, respectively; DME = 1,2-dimethoxyethane], and with reference to previously reported [Li(DME)3][Er(COT1,4-TMS2)2] (A) and [K(DME)2][Er(COT1,4-TMS2)2] (B), any possible substituent position effects have been explored for the first time. The rearrangement of the TMS substituents from the starting COT1,4-TMS2 to COT1,3-TMS2 and COT1,5-TMS2, by way of formal migration of the TMS group, was thermally induced in the case of Er1, while for the formation of Er2, the use of Na+ in the placement of its Li+ and K+ congeners is essential. Both Er1 and Er2 display single-molecule magnetic behaviors with energy barriers of 170(3) and 172(6) K, respectively. Magnetic hysteresis loops, butterfly-shaped for Er1 and wide open for Er2, were observed up to 12 K for Er1 and 13 K for Er2. Studies of magnetic dynamics reveal the different pathways for relaxation of magnetization below 10 K, mainly by the Raman process for Er1 and by quantum tunneling of magnetization for Er2, leading to the order of magnitude difference in magnetic relaxation times and sharply different magnetic hysteresis loops.

Two-Electron Oxidations at a Single Cerium Center.

Two-electron oxidations are ubiquitous and play a key role in the synthesis and catalysis. For transition metals and actinides, two-electron oxidation often takes place at a single-metal site. However, redox reactions at rare-earth metals have been limited to one-electron processes due to the lack of accessible oxidation states. Despite recent advancements in nontraditional oxidation state chemistry, the low stability of low-valent compounds and large disparity among different oxidation states prevented the implementation of two-electron processes at a single rare-earth metal center. Here we report two-electron oxidations at a cerium(II) center to yield cerium(IV) terminal oxo and imido complexes. A series of cerium(II-IV) complexes supported by a tripodal tris(amido)arene ligand were synthesized and characterized. Experimental and theoretical studies revealed that the cerium(II) complex is best described as a 4f2 ion stabilized by δ-backdonation to the anchoring arene, while the cerium(IV) oxo and imido complexes exhibit multiple bonding characters. The accomplishment of two-electron oxidations at a single cerium center brings a new facet to molecular rare-earth metal chemistry.

Piezochromism and Conductivity Modulations under High Pressure by Manipulating the Viologen Radical Concentration.

Manipulating the radical concentration to modulate the properties in solid multifunctional materials is an attractive topic in various frontier fields. Viologens have the unique redox capability to generate radical states through reversible electron transfer (ET) under external stimuli. Herein, taking the viologens as the model, two kinds of crystalline compounds with different molecule-conjugated systems were designed and synthesized. By subjecting the specific model viologens to pressure, the cross-conjugated 2-X all exhibit much higher radical concentrations, along with more sensitive piezochromic behaviors, compared to the linear-conjugated 1-X. Unexpectedly, we find that the electrical resistance (R) of 1-NO3 decreased by three orders of magnitude with the increasing pressure, while that in high-radical-concentration 2-NO3 remained almost unchanged. To date, such unusual invariant conductivity has not been documented in molecular-based materials under high pressure, breaking the conventional wisdom that the generations of radicals are beneficial to improve conductivity. We highlight that adjusting the molecular conjugation modes can be used as an effective way to regulate the radical concentrations and thus modulate properties rationally.

Tunable Chromic Properties of Viologen-Metal Polymers Modulated by Coordination Modes for Inkless Erasable Printing.

Inkless and erasable printing (IEP) based on chromic materials holds great promise to alleviate environmental and sustainable problems. Metal-organic polymers (MOPs) are bright platforms for constructing IEP materials. However, it is still challenging to design target MOPs with excellent specific functions rationally due to the intricate component-structure-property relationships. Herein, an effective strategy was proposed for the rational design IEP-MOP materials. The stimuli-responsive viologen moiety was introduced into the construction of MOPs to give it potential chromic behaviors and two different coordination models (i. e. bilateral coordination model, M1 ; unilateral coordinated model, M2 ) based on the same viologen ligand were designed. Aided by theoretical calculations, model M1 was recommended secondarily as a more suitable system for IEP materials. Along this line, two representative viologen-ZnII MOPs 1 and 2 with models M1 and M2 were synthesized successfully. Experiments exhibit that 1 does have quicker stimuli response, stronger color contrast and longer radical lifetime compared to 2. Significantly, the obtained 1-IEP media brightly inherits the excellent chromic characteristics of 1 and the flexibility of the paper at the same time, which achieves most daily printing requirements, as well as enough resolution and durability to be used in identification by smart device.

Adaptability to Crystal Fields in a Series of COT/Monodentate Ligand-Based Dy and Er Single Ion Magnets.

Herein, DyIII and ErIII, the typical oblate and prolate Kramers Ln ions, were employed to synthesize a series of isostructural pairs: 2-5Ln (Ln = Dy and Er). In the [(COT)Ln(THF)4]+ cationic fragments of 2Ln, central ions were coordinated by the equatorial ligand cyclooctatetraenyl (COT) and THF solvents, while in the heteroleptic complexes 3Ln ((COT)Ln(OAr')), 4Ln ((COT)Ln(OAr″)), and 5Ln ((COT)Ln(N††)), the coordination geometries were formed by the cooperation of COT and bulky aryloxides OAr' (2,6-bis(diphenylmethyl)-4-methylphenyl), OAr″ (2,6-bis(1-adamantyl)-4-methylphenyl), and amide N†† (bis(triisopropylsilyl) amide) for 3Ln, 4Ln, and 5Ln, respectively. Among these complexes, with the combinations of varying coordination geometries and different anisotropies of f orbitals, 2Er, 3Dy, and 4Dy were found to be zero-field SIMs with effective energy barriers of 181.9, 527.7, and 622.0 K, respectively, which are consistent with the structural analyses and ab initio calculations. The blocking temperatures (TB) of 3Dy and 4Dy are 4 and 7 K, respectively, as confirmed by the hysteresis loops at varying temperatures. The structures of 5Ln exhibit an almost perfect umbrella-shaped geometry, characterized by N-Ln-Centroid (COT) angles measuring 178.9 and 179.3° for 5Dy and 5Er, respectively. Crystallographic data from these structures were utilized to investigate the impact of ligand alignment on the magnetic properties of the compounds.

Two Pairs of Homochiral Parallelogram-like Dy4 Cluster Complexes with Strong Magneto-Optical Properties.

Two pairs of homochiral Dy(III) tetranuclear cluster complexes derived from (+)/(-)-3-trifluoroacetyl camphor (D-Htfc/L-Htfc), [Dy4(OH)2(L1)4(D-tfc)2(DMF)2]·4DMF (D-1) [H2L1 = (E)-2-(2-hydroxy-3-methoxybenzylideneamino)phenol)]/[Dy4(OH)2(L1)4(L-tfc)2(DMF)2]·4DMF (L-1) and [Dy4(OH)2(L2)4(D-tfc)2(DMF)2]·2H2O·3MeCN (D-2) [H2L2 = (E)-3-(2-hydroxy-3-methoxybenzylideneamino)naphthalen-2-ol]/[Dy4(OH)2(L2)4(L-tfc)2(DMF)2]·2H2O·3MeCN (L-2), were synthesized at room temperature, which have a Dy4 parallelogram-like core. The magnetic studies revealed that D-1 exhibits single-molecule magnet (SMM) behavior under zero dc magnetic field, and its magnetic relaxation has a distinct Raman process in addition to the Orbach process, with the Ueff/k value of 57.5 K and the C value of 28.27 s-1K-2.14; while D-2 displays dual magnetic relaxation behavior at 0 Oe field, with the Ueff/k value 114.8 K for the slow relaxation process (SR) and the C value of 10.656 s-1K-5.80 for the fast relaxation process (FR), respectively. Theoretical calculations indicated that the conjugated groups (phenyl vs naphthyl) of the Schiff base bridging ligands (H2L1 and H2L2) significantly affect the intramolecular magnetic interactions between the Dy3+ ions and ultimately lead to different relaxations. Furthermore, magnetic circular dichroism (MCD) measurements showed that these two pairs of Dy4 enantiomers exhibit strong room temperature magneto-optical Faraday effects; notably, increasing the conjugated group on the Schiff base bridging ligand is beneficial to enhancing the magneto-optical Faraday effects.

A phase III randomized, double-blind, placebo-controlled trial of the denosumab biosimilar QL1206 in postmenopausal Chinese women with osteoporosis and high fracture risk.

The current study evaluated the efficacy and safety of a denosumab biosimilar, QL1206 (60 mg), compared to placebo in postmenopausal Chinese women with osteoporosis and high fracture risk. At 31 study centers in China, a total of 455 postmenopausal women with osteoporosis and high fracture risk were randomly assigned to receive QL1206 (60 mg subcutaneously every 6 months) or placebo. From baseline to the 12-month follow-up, the participants who received QL1206 showed significantly increased bone mineral density (BMD) values (mean difference and 95% CI) in the lumbar spine: 4.780% (3.880%, 5.681%), total hip :3.930% (3.136%, 4.725%), femoral neck 2.733% (1.877%, 3.589%) and trochanter: 4.058% (2.791%, 5.325%) compared with the participants who received the placebo. In addition, QL1206 injection significantly decreased the serum levels of C-terminal crosslinked telopeptides of type 1 collagen (CTX): -77.352% (-87.080%, -66.844%), and N-terminal procollagen of type l collagen (P1NP): -50.867% (-57.184%, -45.217%) compared with the placebo over the period from baseline to 12 months. No new or unexpected adverse events were observed. We concluded that compared with placebo, QL1206 effectively increased the BMD of the lumbar spine, total hip, femoral neck and trochanter in postmenopausal Chinese women with osteoporosis and rapidly decreased bone turnover markers. This study demonstrated that QL1206 has beneficial effects on postmenopausal Chinese women with osteoporosis and high fracture risk.

Effects of Counterions, Coordination Anions, and Coordination Solvent Molecules on Single-Molecule Magnetic Behaviors and Nonlinear Optical Properties of Chiral Zn2Dy Schiff Base Complexes.

By changing the counterions (ClO4- and CF3SO3-) and the coordination anions (Cl- and Br-), we investigated their influences on the structures and performances of a class of Zn2Dy chiral single-molecule magnets (SMMs), which are based on a pair of chiral Schiff bases R,R-H2LSchiff and S,S-H2LSchiff {R,R-H2LSchiff = 2-((E)-((1R,2R)-2-((E)-2-hydroxy-3-methoxybenzylideneamino)cyclohexylimino)methyl)-6-methoxyphenol and S,S-H2LSchiff = 2-((E)-((1S,2S)-2-((E)-2-hydroxy-3-methoxybenzylideneamino)cyclohexylimino)methyl)-6-methoxyphenol}. Three pairs of chiral Zn2Dy Schiff base complexes were obtained by directed synthesis, which are [DyZn2(R,R-LSchiff)Cl2(H2O)](ClO4)·0.5MeOH·0.25H2O (R-1) and [DyZn2(S,S-LSchiff)Cl2(H2O)][DyZn2(S,S-LSchiff)Cl2(MeOH)](ClO4)2·MeOH·0.5H2O (S-1), [DyZn2(R,R-LSchiff)Cl2(H2O)](CF3SO3)·0.5MeOH (R-2) and [DyZn2(S,S-LSchiff)Cl2(H2O)][DyZn2(S,S-LSchiff)Cl2(MeOH)](CF3SO3)2·MeOH (S-2), and [DyZn2(R,R-LSchiff)Br2(H2O)](CF3SO3)·0.25MeOH (R-3) and [DyZn2(S,S-LSchiff)Br2(H2O)][DyZn2(S,S-LSchiff)Br2(MeOH)](CF3SO3)2 (S-3). They all exhibit good SMM behaviors, and their magnet relaxation is regulated by not only the counterions (ClO4- and CF3SO3-) but also the coordination anions (Cl- and Br-); these anions also have important effects on the second-harmonic generation (SHG) and third harmonic generation (THG) nonlinear optical properties. Interestingly, in the S-configuration complexes, the coordination solvent molecule of the Dy3+ ion on half of the molecules is the methanol molecule instead of the water molecule. This change in the coordinating solvent molecule can also significantly affect the SMM behaviors and the SHG and THG nonlinear optical properties. Moreover, ab initio calculations were applied to rationally explain the SMM properties.

Unprecedented Ferroelectricity and Ferromagnetism in a Cr2+ -Based Two-Dimensional Hybrid Perovskite.

Organic-inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two-dimensional Cr2+ -based OIHP, [3,3-difluorocyclobutylammonium]2 CrCl4 ([DFCBA]2 CrCl4 ), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 µC cm-2 . It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices.

Bioinspired Design of seco-Chlorin Photosensitizers to Overcome Phototoxic Effects in Photodynamic Therapy.

Photodynamic therapy (PDT) is a non-invasive treatment modality against a range of cancers and nonmalignant diseases, however one must be aware of the risk of causing phototoxic reactions after treatment. We herein report a bioinspired design of next-generation photosensitizers (PSs) that not only effectively produce ROS but undergo fast metabolism after treatment to overcome undesirable side effects. We constructed a series of ß-pyrrolic ring-opening seco-chlorins, termed beidaphyrin (BP), beidapholactone (BPL), and their zinc(II) derivatives (ZnBP and ZnBPL), featuring intense near-infrared absorption and effective O2 photosensitization. Irradiation of ZnBPL led to a non-cytotoxic, metabolizable beidaphodiacetamide (ZnBPD) via in situ generated O2.- but not 1 O2 , as revealed by mechanistic studies including time-resolved absorption, kinetics, and isotope labeling. Furthermore, water-soluble ZnBPL showed an effective therapeutic outcome, fast metabolism, and negligible phototoxic reactions.

Homochiral Ferromagnetic Coupling Dy2 Single-Molecule Magnets with Strong Magneto-Optical Faraday Effects at Room Temperature.

By the bridging action of the 6-chloro-2-hydroxypyridine (Hchp) ligand and the terminal coordination role of the homochiral ligand, (-)/(+)-3-trifluoroacetyl camphor (l-Htfc/d-Htfc), a pair of enantiomerically pure dysprosium(III) dinuclear complexes, [Dy2(l-tfc)4(chp)2(MeOH)2] (l-1) and [Dy2(d-tfc)4(chp)2(MeOH)2] (d-1), was obtained. Their circular dichroism (CD) spectra verified their enantiomeric nature. Magnetic investigation indicated that they exhibit ferromagnetic interaction and good zero field single-molecule magnet (SMM) properties. The Ueff/k values of l-1 and d-1 at 0 Oe are 180.5 and 181.3 K, respectively, which are large values for homochiral Dy(III) SMMs. A reasonable explanation for the magnetic properties of l-1 and d-1 was supplied by ab initio calculations. Remarkably, magnetic circular dichroism (MCD) investigation revealed that the chiral Dy2 enantiomers show a strong magneto-optical Faraday effect at room temperature, suggesting potential applications in magneto-optical devices.

Tri-Manganese(III) Salen-Based Cryptands: A Metal Cooperative Antioxidant Strategy that Overcomes Ischemic Stroke Damage In Vivo.

Oxidative stress is one of the hallmarks of ischemic stroke. Catalase-based (CAT) biomimetic complexes are emerging as promising therapeutic candidates that are expected to act as neuroprotectants for ischemic stroke by decreasing the damaging effects from H2O2. Unfortunately, these molecules result in the unwanted production of the harmful hydroxyl radical, HO•. Here, we report a series of salen-based tri-manganese (Mn(III)) metallocryptands (1-3) that function as catalase biomimetics. These cage-like molecules contain a unique "active site" with three Mn centers in close proximity, an arrangement designed to facilitate metal cooperativity for the effective dismutation of H2O2 with minimal HO• production. In fact, significantly greater oxygen production is seen for 1-3 as compared to the monomeric Mn(Salen) complex, 1c. The most promising system, 1, was studied in further detail and found to confer a greater therapeutic benefit both in vitro and in vivo than the monomeric control system, 1c, as evident from inter alia studies involving a rat model of ischemic stroke damage and supporting histological analyses. We thus believe that metallocryptand 1 and its analogues represent a new and seemingly promising strategy for treating oxidative stress related disorders.

Adducts of Tris(alkyl) Holmium(III) Showing Magnetic Relaxation.

In the series of the adducts of tris(alkyl) HoIII complexes, Ho(CH2SiMe3)3(THF)2 (1Ho-THF, Me = methyl) can exhibit slow magnetic relaxation under a zero applied direct current (DC) field with the energy barrier Δ/kB of 76 K, which is one of the highest in the non-Kramers ion HoIII-based single-ion magnets (SIMs). The DC field-dependence of relaxation time for 1Ho-THF indicates the occurrence of direct relaxation process at low temperature under certain DC fields. 1Ho-THF stands out in the series of 1Ln-THF (Ln = Tb, Dy, Ho, Er, Tm), wherein Dy congener is another SIM in the absence of a DC field with the relaxation barrier of 40 K, while Tb and Er congeners are field-induced SIMs. Further substitutions of the two trans-THF in 1Ho-THF by other neutral ligands such as quinuclidine, tricyclohexylphosphine oxide, and 3,5-lutidine afforded Ho(CH2SiMe3)3(quinuclidine)2 (2Ho-QN), Ho(CH2SiMe3)3(OPCy3)2 (3Ho-OPCy3), and Ho(CH2SiMe3)3(lutidine)3 (4Ho-Lut), respectively. The former two possess analogous structures to 1Ho-THF with two trans-arranged neutral ligands, and the latter one has three cis-lutidine coordinated. The fast quantum tunneling effect swamps the magnetic relaxation for the above three derivatives, so slow relaxation could not be observed under experimental conditions, even when a certain DC field was applied.

An efficient TILLING platform for cultivated tobacco.

Targeting-induced local lesions in genomes (TILLING) is a powerful reverse-genetics tool that enables high-throughput screening of genomic variations in plants. Although TILLING has been developed for many diploid plants, the technology has been used in very few polyploid species due to their genomic complexity. Here, we established an efficient capillary electrophoresis-based TILLING platform for allotetraploid cultivated tobacco (Nicotiana tabacum L.) using an ethyl methanesulfonate (EMS)-mutagenized population of 1,536 individuals. We optimized the procedures for endonuclease preparation, leaf tissue sampling, DNA extraction, normalization, pooling, PCR amplification, heteroduplex formation, and capillary electrophoresis. In a test screen using seven target genes with eight PCR fragments, we obtained 118 mutants. The mutation density was estimated to be approximately one mutation per 106 kb on average. Phenotypic analyses showed that mutations in two heavy metal transporter genes, HMA2S and HMA4T, led to reduced accumulation of cadmium and zinc, which was confirmed independently using CRISPR/Cas9 to generate knockout mutants. Our results demonstrate that this powerful TILLING platform (available at http://www.croptilling.org) can be used in tobacco to facilitate functional genomics applications.

A Gallium(III) Complex that Engages Protein Disulfide Isomerase A3 (PDIA3) as an Anticancer Target.

Gallium(III)-based drugs have gained momentum in cancer therapy due to their iron-dependent anticancer activity. Judicious choice of ligands is critical for improved oral bioavailability, antitumor efficacy, and distinct mechanisms from simple GaIII salts. We describe GaIII complexes with planar tetradentate salen ligands [salen=2,3-bis[(4-dialkylamino-2-hydroxybenzylidene)amino]but-2-enedinitrile)] and labile axial solvent ligands, which display tumor growth inhibition in vitro and in vivo comparable to cisplatin. Confocal fluorescence microscopy, western blotting, mRNA profiling, chemical proteomics, and surface plasmon resonance (SPR) studies provide compelling evidence that PDIA3, a member of the protein disulfide isomerase (PDI) family involved in endoplasmic reticulum (ER) stress, is a direct target of Ga-1. This work offers a new route to designing and synthesizing Ga-based drugs, and also reveals that PDIA3 is an important anticancer target.

Experimental Determination of Magnetic Anisotropy in Exchange-Bias Dysprosium Metallocene Single-Molecule Magnets.

We investigate a family of dinuclear dysprosium metallocene single-molecule magnets (SMMs) bridged by methyl and halogen groups [Cp'2 Dy(µ-X)]2 (Cp'=cyclopentadienyltrimethylsilane anion; 1: X=CH3 - ; 2: X=Cl- ; 3: X=Br- ; 4: X=I- ). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.3°) due to the stronger equatorial interactions between DyIII and methyl groups. Moreover, its magnetic axes show a temperature-dependent shifting, which is caused by the competition between exchange interactions and Zeeman interactions. Studies of fluorescence and specific heat as well as ab initio calculations reveal the significant influences of the bridging ligands on their low-lying exchange-based energy levels and, consequently, low-temperature magnetic properties.

Three New Niccolites: High-Temperature Phase Transitions, Prominent Anisotropic Thermal Expansions, Dielectric Anomalies, and Magnetism.

Three new iso-structural ammonium metal formates of [dmpnH2 ][M2 (HCOO)6 ], in which dmpnH2 2+ =N,N'-dimethyl-1,3-propylenediammoium and M=divalent Co, Zn and Mg ions, are reported. They possess niccolite metal formate frameworks with long-shaped cavities for the accommodation of dmpnH2 2+ cations. The three materials display reversible phase transitions of similar mechanism from ordered, antipolar or antiferroelectric, low-temperature phases in space group C2/c, to disordered, paraelectric, high-temperature phases in space group P 3 ‾ 1c, with quite high critical temperatures of 366, 370, and 334 K for Co, Zn, and Mg members, respectively. On warming, the dmpnH2 2+ cation experiences an ordered state with gradual increase of the local vibration motions of the central CH2 and terminal CH3 groups, a partially disordered state with gradually enhanced flipping motion between the major and minor orientations, and finally a twisting or rotating motion after the phase transition, accompanied by prominent anisotropic thermal expansions and dielectric anomalies/relaxations. The phase transition characters and relevant properties also exhibit a subtle metal-dependence. The Co member shows spin-canted antiferromagnetism below the Néel temperature of 16.1 K, with unusual large spontaneous magnetization and coercive field.

Endohedral Metallofullerene as Molecular High Spin Qubit: Diverse Rabi Cycles in Gd2@C79N.

An anisotropic high-spin qubit with long coherence time could scale the quantum system up. It has been proposed that Grover's algorithm can be implemented in such systems. Dimetallic aza[80]fullerenes M2@C79N (M = Y or Gd) possess an unpaired electron located between two metal ions, offering an opportunity to manipulate spin(s) protected in the cage for quantum information processing. Herein, we report the crystallographic determination of Gd2@C79N for the first time. This molecular magnet with a collective high-spin ground state (S = 15/2) generated by strong magnetic coupling (JGd-Rad = 350 ± 20 cm-1) has been unambiguously validated by magnetic susceptibility experiments. Gd2@C79N has quantum coherence and diverse Rabi cycles, allowing arbitrary superposition state manipulation between each adjacent level. The phase memory time reaches 5 µs at 5 K by dynamic decoupling. This molecule fulfills the requirements of Grover's searching algorithm proposed by Leuenberger and Loss.

Coupling Influences SMM Properties for Pure 4 f Systems.

Increasing both the energy barrier for magnetization reversal and the coercive field of the hysteresis loop are significant challenges in the field of single-molecule magnets (SMMs). Coordination geometries of lanthanide ions and magnetic interactions between lanthanide ions are both important for guiding the magnetic behavior of SMMs. We report a high energy barrier of 657 K (457 cm-1 ) in a diamagnetic-ion-diluted lanthanide chain compound with a constrained bisphenoid symmetry (D2d ); this energy barrier is substantially higher than the barrier of 567 K (394 cm-1 ) of the non-diluted chain compound with intrachain ferromagnetic interactions. Although intrachain magnetic interaction lowers the energy barrier for magnetization reversal, it can greatly enhance the coercive fields and zero-field remanence of the hysteresis loops, which is crucial for the rational design of high-performance SMMs. Factors related to the coordination sphere of the lanthanide center, which govern the high magnetic relaxation barriers through the second excited Kramer's doublets and the magnetic interactions that affect the hysteresis loops, were revealed through ab initio calculations.

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)][ClO4]2·2CH3CN·H2O (1). Magnetic study showed that 1 exhibited large uniaxial magnetic anisotropy with a zero-field-splitting parameter of -80.7 cm-1 and typical single-molecule-magnet behavior.