Induction of osteoclast formation by LOX mutant (LOXG473A) through regulation of autophagy.

BACKGROUND: Lysyl oxidase (LOX) has been identified to modulate osteoclast activity, so we explored the role of LOXG473A, the highest frequency single nucleotide polymorphism in LOX, in osteoclast formation and its potential relationship to autophagy. METHODS: The ability of the LOX mutant, LOXG473A, to promote autophagy and osteoclast formation was evaluated in the pre-osteoclast cell line RAW264.7. Furthermore, autophagy-related protein expression and autophagosomes were detected by western blot and electron microscopy, respectively. Simultaneously, osteoclast formation and resorption ability were also detected using TRAP staining assay and bone resorption assay. In addition, the osteoclast-related proteins and mRNAs, as well as p-AMPKα and p-mTOR proteins, were further evaluated by western blot and qPCR assays. RESULTS: Autophagy inhibitor 3-MA suppressed the Beclin-1 and ATG5 protein levels and the ratio of LC3-II to LC3-I, as well as autophagosome formation in RAW264.7 transfected with the MUT plasmid and enhanced p62 protein expression. Simultaneously, 3-MA also reduced osteoclast formation and resorption, as well as the F-actin ring level of osteoclasts. In addition, 3-MA inhibited osteoclast-related protein and mRNA expression, including NFATC1, ACP5, CTSK. And the autophagy-related pathway protein p-AMPKα was increased and p-mTOR was reduced by 3-MA treatment. However, autophagy agonist RAPA reversed the effect of 3-MA on RAW264.7 with LOXG473A mutation, indicating that promoting autophagy could enhance the ability of LOXG473A to induce osteoclast formation. CONCLUSIONS: LOX mutant (LOXG473A) might promote osteoclast formation for RAW264.7 by enhancing autophagy via the AMPK/mTOR pathway, which is a new direction for bone disease research.

[Progress of the application research of acupuncture anesthesia in thyroid surgery].

This article reviews the clinical studies on the application of acupuncture anesthesia in thyroid surgery over the past 5 years. Starting from the principle of acupuncture anesthesia, the authors explore the application of acupuncture anesthesia in thyroid surgery, its advantages and development. The summarized findings showed that acupuncture anesthesia has a better analgesic effect in thyroid surgery, which can reduce the occurrence of stress reactions, adverse reactions and complications, and is conducive to postoperative recovery. However, there is a lack of standardized operations. In the future, standardized operations can make acupuncture anesthesia more widely used and popularized.

GRP78 activates the Wnt/HOXB9 pathway to promote invasion and metastasis of hepatocellular carcinoma by chaperoning LRP6.

Recent studies have shown that the expression levels of glucose-regulated protein 78 (GRP78) and homeobox B9 (HOXB9) are both upregulated in hepatocellular carcinoma (HCC) and are closely related to HCC invasion and metastasis. However, whether there is a regulatory relationship between GRP78 and HOXB9 is unclear. In this study, we examined the expression of GRP78 and HOXB9 in HCC tissues and adjacent nontumor tissues. Correlation analysis indicated that GRP78 and HOXB9 expression were positively correlated. High levels of GRP78 and HOXB9 expression are closely related to worse clinicopathological features. Knockdown of GRP78 in HCC cells decreased the mRNA and protein expression of HOXB9, but increase HOXB9 expression reversed the decrease in invasion and metastasis induced by knocking down GRP78. Further experiments showed that GRP78 regulates HOXB9 through the Wnt signaling pathway by chaperoning low-density lipoprotein receptor-related protein 6 (LRP6). Importantly, we found that GPR78 promoted maturation of LRP6, while knockdown of GRP78 led to LRP6 misfolding and endoplasmic reticulum-associated degradation (ERAD). Consequently, the levels of mature LRP6 were reduced, and Wnt/HOXB9 signaling was inhibited. Our data suggest that the GRP78-LRP6-HOXB9 axis regulates the invasion and metastasis of HCC and may represent a potential therapeutic target for the treatment of HCC.

An eight-coordinate ytterbium complex with a hexagonal bipyramid geometry exhibiting field-induced single-ion magnet behaviour.

Two isostructural eight-coordinate complexes Ln(NO3)3(tBu3PO)2 (Ln = Yb, 1-Yb; Tb, 2-Tb) were synthesized and structurally analyzed by single-crystal X-ray crystallography. Both complexes feature a nearly perfect hexagonal bipyramidal LnO8 geometry with ideal D3h symmetry. Magnetic measurements show field-induced slow magnetic relaxation for 1-Yb, thereby presenting the first report of YbIII-based SIMs with a hexagonal bipyramidal coordinate geometry. In contrast, 2-Tb shows no significant out-of-phase (χ''M) ac signals.

Functional Variants in Linc-ROR are Associated with mRNA Expression of Linc-ROR and Breast Cancer Susceptibility.

Functional polymorphisms in Linc-ROR may change its ability of regulation by regulating Linc-ROR expression. However, these functional polymorphisms in Linc-ROR and their associations with breast cancer (BC) susceptibility were scarcely reported. In this molecular epidemiological study, four SNPs (rs6420545, rs4801078, rs1942348 and rs9636089) were selected in Linc-ROR by bioinformatics method. Unconditional logistic regression model was performed to analyze the associations between four SNPs and BC susceptibility adjusted for reproductive factors. Quantitative real-time (qRT) PCR was used to evaluate relative expression of Linc-ROR in plasma. The interactions of gene reproductive factors were assessed by Multifactor Dimensionality Reduction (MDR) method. A novel finding showed TT (OR: 1.79; 95%CI: 1.20-2.68) genotype of rs4801078 in Linc-ROR had a significant association with the higher risk of BC and the expression of Linc-ROR mRNA was closely related with the alleles of rs4801078. In addition, we found the interaction of rs4801078, number of pregnancy and menopausal status might increase BC risk (OR: 2.78; 95%CI: 2.74-3.61). Our results suggest that interactions of SNPs in Linc-ROR and reproductive factors might contribute to BC risk, and alleles of rs4801078 might affect Linc-ROR expression level.

GRP78 Promotes Hepatocellular Carcinoma proliferation by increasing FAT10 expression through the NF-κB pathway.

Glucose-regulated protein 78(GRP78) and the ubiquitin-like protein FAT10 each promote proliferation in hepatocellular carcinoma(HCC). However, the relationship of GRP78 and FAT10 in HCC proliferation are still not known. In this study, we found that GRP78 and FAT10 were significantly overexpressed in HCC tissues compare with adjacent non-cancerous tissues, and a positive correlation was found between their expression and associated proliferation characteristics. High expression of GRP78 and FAT10 were positively correlated with tumor proliferation and poor prognosis in HCC. Moreover, GRP78 knockdown reduced FAT10 expression and suppressed HCC proliferation in vitro and in vivo. The effects of GRP78 knockdown were rescued by FAT10 up-regulation, whereas FAT10 knockdown reduced HCC proliferation enhanced by GRP78 up-regulation. Furthermore, GRP78 modulated FAT10 expression by regulating the NF-κB pathway, direct activation of the NF-κB pathway increased the expression of FAT10, a gene counteracting the tumor suppressor p53. Taken together, these results suggest that this newly identified GRP78-NF-κB-FAT10 axis will provide novel insight into the understanding of the regulatory mechanisms of proliferation in human HCC.

Association analyses of genetic variants in long non-coding RNA MALAT1 with breast cancer susceptibility and mRNA expression of MALAT1 in Chinese Han population.

The long non-coding RNA (lncRNA) Metastasis-associated lung adenocarcinoma transcript 1(MALAT1) has been implicated in breast cancer (BC). Polymorphisms in MALAT1 may play a vital role in the progress of breast cancer by its regulation function. However, potential genetic variants in MALAT1 affecting the development of BC is rarely explored. In our current molecular epidemiology study, all three tagging SNPs (rs3200401, rs619586 and rs7927113) in lncRNA MALAT1 were selected for genotyping in 487BCE patients and 489 cancer-free controls in Chinese Han population, and futher experiment of quantitative real-time (qRT) PCR was conducted to examine the relative expression of MALAT1. The results showed that individuals with genotype AG of rs619586 has a decreased risk of BC in codominant model (OR: 0.684, 95%CI: 0.478-0.979), dominant mode (OR: 0.675, 95%CI: 0.479-0.951) and over-dominant model (OR: 0.692, 95%CI: 0484-0.989). Also, qRT-PCR results revealed that the expression for MALAT1 with AG (0.827±0.490), GG (0.511±0.149) and AG+GG genotypes (0.743±0.447) of rs619586 was significantly lower than that with genotype AA (1.511±0.737). In addition, females with genotype CT of rs3200401 had a lower risk of BC in the codominant model (OR: 0.75, 95%CI: 0.559-1.007) and over-dominant model (OR: 0.741, 95%CI: 0.552-0.993). In summary, our results implied that the genetic variants of lncRNA MALAT1 were associated with the susceptibility of BC, and meaningful genetic alteration might affect the corresponding mRNA expression of lncRNA MALAT1.

Serum autoantibodies against a panel of 15 tumor-associated antigens in the detection of ovarian cancer.

In this study, enzyme-linked immunosorbent assay has been used to examine the frequencies of serum autoantibodies against two candidate tumor-associated antigens intensively selected from the Human Protein Atlas database, in combination with 13 tumor-associated antigens available from our lab in sera from 44 OC patients and 50 normal healthy controls. Conventional evaluation (mean + 3SD as the cutoff value to determine a positive reactivity), receiver operating characteristic curve analyses, and classification tree analysis were further used to evaluate the diagnostic performance of autoantibodies against these tumor-associated antigens (anti-tumor-associated antigens) in ovarian cancer. For single anti-tumor-associated antigen, when the cutoff values were set as mean + 3SD of normal healthy controls, NPM1, MDM2, PLAT, p53, and c-Myc could achieve sensitivity higher than 20% at 98% specificity. Combinational utilization of autoantibodies against MDM2, PLAT, NPM1, 14-3-3 Zeta, p53, and RalA achieved the optimal diagnostic performance with 72.7% sensitivity at 96% specificity. Receiver operating characteristic curve analysis showed that the area under the receiver operating characteristic curves of autoantibodies against c-Myc, NPM1, MDM2, p16, p53, and 14-3-3 Zeta were greater than 0.80. This indicated that these tumor-associated antigens held high potential to serve as diagnostic biomarkers in ovarian cancer detection. Decision tree analysis indicated that anti-c-Myc held high potential in the detection of ovarian cancer. Further studies are warranted to validate the diagnostic performance of these anti-tumor-associated antigens with high area under the receiver operating characteristic curve, including autoantibodies against c-Myc, MDM2, PLAT, NPM1, 14-3-3 Zeta, p53, and RalA.

rs15869 at miRNA binding site in BRCA2 is associated with breast cancer susceptibility.

BRCA1 and BRCA2 mutations confer an increased lifetime risk of breast cancer; however, the associations of microRNA (miRNA) binding site single nucleotide polymorphisms (SNPs) in 3' untranslated region (3'-UTR) of BRCA1 and BRCA2 with breast cancer (BC) risk were rarely reported. In this case-control study (498 BC patients and 498 matched controls), three SNPs (rs8176318, rs12516 and rs15869) were selected in the 3'-UTR of BRCA1 and BRCA2 genes, which were within miRNA-binding seed regions and might have potential function to regulate the expression of BRCA1/BRCA2. Unconditional logistic regression model was used to analyze the association between three SNPs and BC risk with adjustment of reproductive factors, and Student's t test was performed to assess relative expression of BRCA2 in human breast cancer cell lines. Multifactor dimensionality reduction method was applied to calculate gene-reproductive factors interactions. A novel finding showed that AC [odds ratio (OR) 1.524; 95% confidence interval (CI) 1.141-2.035] genotype of rs15869 in BRCA2 could increase the risk of BC and recombinant plasmid-pGenesil-1-miR-627 could negatively regulate the expression of BRCA2 in MCF-7 and MDA-MB-231 cells. Gene-reproductive factors interactions analysis revealed that rs15869 together with age at menarche and number of pregnancy could increase the risk of BC by 2.39-fold and TT genotype (OR 0.316; 95% CI 0.130-0.767) of rs8176318 had a significant association with progesterone receptor status in BC patients. Our findings suggest that the miRNA-binding SNPs in BRCA1/BRCA2 and their interaction with reproductive factors might contribute to BC risk, and miR-627 might down-regulate BRCA2 expression in MCF-7 and MDA-MB-231 cells.

Methylation of CDX2 as a Predictor in Poor Clinical Outcome of Patients with Colorectal Cancer.

AIM: Increased DNA methylation within the promoter regions of tumor suppressor genes has been associated with gene silencing in various cancers. CDX2, a caudal-related homeobox transcription factor, represents a key tumor suppressor in colorectal cancer. However, the pathological role of its promoter methylation has not yet been well defined in colorectal cancer. METHODS: We measured CDX2 promoter methylation by methylation-specific PCR (MSP) and CDX2 mRNA levels by real-time quantitative reverse transcription-PCR in both tumor and normal control tissues collected from 108 colorectal cancer patients and then performed correlation analyses. We also determined whether CDX2 promoter methylation status was associated with any clinicopathological features and prognosis in these patients. RESULTS: CDX2 was expressed in all normal mucosa, but only in 38 (35.2%) tumor tissues. CDX2 promoter methylation was detected in 43 (39.8%) tumor samples, but in none of the normal tissue specimens. DNA methylation correlated with decreased mRNA level in these tumors (p < 0.05). The methylation of the CDX2 promoter was associated with enhanced lymph node metastases and shorter survival time (p = 0.0273), but was independent of tumor stage, tumor differentiation, gender, and age. CONCLUSION: Enhanced CDX2 promoter methylation is associated with gene silencing in a subgroup of colorectal cancer patients with lymph node metastasis and shorter survival times.

MiRNA-binding site functional polymorphisms in DNA repair genes RAD51, RAD52, and XRCC2 and breast cancer risk in Chinese population.

RAD51, RAD52, and XRCC2 are all involved in DNA homologous recombinational repair, and there are interactions among those genes. Polymorphisms in 3'-UTR of DNA repair genes may change DNA repair capacity by regulating gene expression. However, potential regulatory variants affecting their expression remain largely unexplored. Five miRNA-binding site SNPs (rs7180135 and rs45549040 in RAD51, rs1051669 and rs7963551 in RAD52 and rs3218550 in XRCC2) selected by bioinformatics method were genotyped in 498 breast cancer (BC) patients and 498 matched controls in Chinese population. Association between SNPs and BC risk was analyzed by adjusted odds ratios (ORs) and 95 % confidence intervals (CIs) in unconditional logistic regression model. Quantitative real-time (qRT) PCR and Western Blot assays were used to calculate the relative expression of RAD52 in recombinant plasmid-pGenesil-1-let-7b group and let-7b-inhibitor group. Gene-reproductive factors interactions were evaluated by multifactor dimensionality reduction (MDR) method. We found that individuals with AC (OR 0.684, 95%CI 0.492-0.951) and CC (OR 0.317, 95%CI 0.200-0.503) genotypes of rs7963551 had a significantly lower risk of breast cancer and qRT-PCR and Western Blot revealed that let-7b might downregulate the expression of RAD52 in MCF-7 and SKBR-3 cells. A significant interaction between the number of pregnancy (≥2) and rs7963551 (Ars7963551) was found to increase breast cancer risk by 2.63-fold (OR 2.63; 95%CI 2.03-3.42). In summary, the miRNA-binding SNPs in DNA repair genes RAD51, RAD52, and XRCC2 and their interaction with reproductive factors might play important roles in the development of BC, and let-7b might downregulate RAD52 expression in MCF-7 and SKBR-3 cells.

The effect of quercetin nanoparticle on cervical cancer progression by inducing apoptosis, autophagy and anti-proliferation via JAK2 suppression.

Cervical cancer is a cause of cancer death, making it as the one of the most common cause for death among women globally. Though many studies before have explored a lot for cervical cancer prevention and treatment, there are still a lot far from to know based on the molecular mechanisms. Janus kinase 2 (JAK2) has been reported to play an essential role in the progression of apoptosis, autophagy and proliferation for cells. We loaded gold-quercetin into poly (dl-lactide-co-glycolide) nanoparticles to cervical cancer cells due to the propertities of quercetin in ameliorating cellular processes and the easier absorbance of nanoparticles. Here, in our study, quercetin nanoparticles (NQ) were administrated to cells to investigate the underlying mechanism by which the cervical cancer was regulated. First, JAK2-inhibited carvical cancer cell lines were involved for our experiments in vitro and in vivo. Western blotting, quantitative RT-PCR (qRT-PCR), ELISA, Immunohistochemistry, and flow-cytometric analysis were used to determine the key signaling pathway regulated by JAK2 for cervical cancer progression. And the role of quercetin nanoparticles was determined during the process. Data here indicated that JAK2, indeed, expressed highly in cancer cell lines compared to the normal cervical cells. And apoptosis and autophagy were found in JAK2-inhibited cancer cells through activating Caspase-3, and suppressing Cyclin-D1 and mTOR regulated by Signal Transducer and Activator of Transcription (STAT) 3/5 and phosphatidylinositide 3-kinase/protein kinases (PI3K/AKT) signaling pathway. The cervical cancer cells proliferation was inhibited. Further, tumor size and weight were reduced by inhibition of JAK2 in vivo experiments. Notably, administration with quercetin nanoparticles displayed similar role with JAK2 suppression, which could inhibit cervical cancer cells proliferation, invasion and migration. In addition, autophogy and apoptosis were induced, promoting cervical cancer cell death. To our knowledge, it was the first time to evaluate the role of quercetin nanoparticles in improving cervical cancer from apoptosis, autophagy and proliferation, which could be a potential target for future therapeutic approach clinically.

Evaluation and characterization of anti-RalA autoantibody as a potential serum biomarker in human prostate cancer.

Autoantibodies against intracellular tumor-associated antigens (TAAs) are commonly found in human cancers. In this study, we characterized the serum autoantibody response to the RalA, Ras-like GTPase, in patients with prostate cancer (PCa). The autoantibodies were detected by immunofluorescence assay in PCa cell lines, ELISA, and immunoblotting in 339 serum samples from patients with PCa and benign prostatic hyperplasia (BPH), and in normal human sera (NHS). The expression of RalA in prostate tumor tissues was evaluated by immunohistochemistry (IHC) in tumor microarrays. The autoantibody level to RalA (median) in NHS was significantly lower than in PCa (0.053 vs 0.138; P < 0.001) and BPH (0.053 vs 0.132; P < 0.005) groups. The circulating anti-RalA autoantibody could distinguish PCa patients from normal individuals with the area under the receiver operating characteristic (ROC) curve (AUC) performing at 0.861, with sensitivity of 52.9% and specificity of 91.0%. Elevation in serum immunoreactivity was observed in PCa patients after radical prostatectomy. The combined use of both anti-RalA autoantibody and PSA showed a significantly higher discriminatory ability compared with either of those markers alone. RalA protein expression was detected by IHC in 85.3% of tumor tissues from PCa patients, but without significant difference compared to BPH or normal control tissues. Together, our study shows the additional benefits of anti-RalA autoantibody as a potential serological biomarker for PCa, particularly in patients with normal PSA, and further demonstrate the utility of biomarker combinations in the immunodiagnosis of PCa.

Autoantibody response to Sui1 and its tissue-specific expression in hepatocellular carcinoma.

To investigate the immunogenicity of Homo sapiens putative translation initiation factor (Sui1) in hepatocellular carcinoma (HCC), enzyme-linked immunosorbent assay (ELISA) and Western blot were utilized to assess autoantibody responses to Sui1 in sera from HCC patients and healthy individuals. Indirect immunofluorescence (IIF) assay with cancer cells and immunohistochemistry (IHC) study with tissue array slides were performed to examine Sui1 expression profile in cancer cells and tissues. The data confirmed that the frequency of autoantibody to Sui1 in sera of HCC patients was 15.5 % (16/103), which was remarkably higher than that in sera of liver cirrhosis (LC) patients (3.3 %, 1/30), chronic hepatitis (CH) patients (0 %, 0/29), and normal human serum (NHS) (0 %, 0/82) (p < 0.01). IHC study showed that the Sui1 expression in HCC tissues was 26.7 % (16/60). The expression of Sui1 had the trend of increasing along with the cancer grades but no statistical significance (p > 0.05). In immunodiagnosis of HCC, the sensitivity and specificity of the anti-Sui1 antibody were 15.5 and 99.3 %, respectively. If both anti-Sui1 and alpha fetal protein (AFP) were simultaneously utilized as detective markers, 66.7 % (30/45) of HCC patients could be correctly distinguished. The results suggested that anti-Sui1 could be utilized as a supplementary serological marker for the detection of HCC and Sui1 might be associated to HCC carcinogenesis.

[Moxibustion at Gaohuang (BL 43) for chronic fatigue syndrome: a randomized controlled trial].

OBJECTIVE: To observe the clinical effect of chronic fatigue syndrome (CFS) treated with moxibustion at Gaohuang (BL 43). METHODS: With stratified block randomization, 72 patients accorded with inclusive criteria were divided into a moxibustion at Gaohuang (BL 43) group (moxibustion group) and an acupuncture group, 36 cases in each one. In the moxibustion group, Gaohuang (BL 43) was treated with big moxa cones as the main acupoint, 10 cones a time; Qihai (CV 6) and Zusanli (ST 36) were added with big moxa cones, 7 cones a time. In the acupuncture group, acupoints were the same as those in the moxibustion group, and twirling reinforcing method was used after qi arriving, 60 times one minute and 360° with range. In the two groups, 10-day treatment was made into one course and there were two days between courses. The treatment was given once a day for 3 courses. Changes of fatigue assessment index (FAI) before and after treatment and clinical effects were observed. RESULTS: The total effective rate was 88.9% (32/36) in the moxibustion group, which was better than 72.2% (26/36) in the acupuncture group apparently (P < 0.05). After treatment in the two groups, FAI scores were obviously declined compared with those before treatment (both P < 0.01) and FAI score in the moxibustion group was apparently lower than that in the acupuncture group (P < 0.05). CONCLUSION: Moxibustion at Gaohuang (BL 43) can improve the FAI score of patients with CFS and the clinical efficacy is definite.

Comment on "electrical-driven transport of endohedral fullerene encapsulating a single water molecule".

A Comment on the Letter by B. Xu and X. Chen, Phys. Rev. Lett. 110, 156103 (2013).

[Discussion on acupuncture for cerebral apoplexy from the view of rehabilitation].

Abundant experiences have already been accumulated in treatment of stroke with acupuncture. Development of rehabilitation theory also brings unprecedented opportunity and challenge to acupuncture. Combined with the modern rehabilitation theory and practice, it is very helpful to deepen the understanding on treatment of acupuncture for cerebral apoplexy and enhance the therapeutic effect in clinic by studying the mechanism of acupuncture treatment, opportunity of intervention, selection of acupoints, needling manipulations and quantity of stimulations etc. Through analysis on the necessity and the way of combination of acupuncture and modern rehabilitation, it is concluded that rehabilitation evaluation, rehabilitation phases and obstacle analysis should be taken as references by acupuncturists to reinforce the therapeutic effect and creditability of acupuncture treatment on cerebral apoplexy.

Exchange coupling and magnetic anisotropy in a family of bipyrimidyl radical-bridged dilanthanide complexes: density functional theory and ab initio calculations.

The origin of the magnetic anisotropy energy barriers in a series of bpym(-) (bpym = 2,2'-bipyrimidine) radical-bridged dilanthanide complexes [(Cp*2Ln)2(µ-bpym)](+) [Cp* = pentamethylcyclopentadienyl; Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Er(III) (5)] has been explored using density functional theory (DFT) and ab initio methods. DFT calculations show that the exchange coupling between the two lanthanide ions for each complex is very weak, but the antiferromagnetic Ln-bpym(-) couplings are strong. Ab initio calculations show that the effective energy barrier of 2 or 3 mainly comes from the contribution of a single Tb(III) or Dy(III) fragment, which is only about one third of a single Ln energy barrier. For 4 or 5, however, both of the two Ho(III) or Er(III) fragments contribute to the total energy barrier. Thus, it is insufficient to only increase the magnetic anisotropy energy barrier of a single Ln ion, while enhancing the Ln-bpym(-) couplings is also very important.

Magneto-structural correlations in a family of Fe(II)Re(IV)(CN)2 single-chain magnets: density functional theory and ab initio calculations.

Until now, the expressions of the anisotropic energy barriers Δξ and ΔA, using the uniaxial magnetic anisotropy D, the intrachain coupling strength J, and the high-spin ground state S for single-chain magnets (SCMs) in the intermediate region between the Ising and the Heisenberg limits, were unknown. To explore this relationship, we used density functional theory and ab initio methods to obtain expressions of Δξ and ΔA in terms of D, J, and S of six R4Fe(II)-Re(IV)Cl4(CN)2 (R = diethylformamide (1), dibutylformamide (2), dimethylformamide (3), dimethylbutyramide (4), dimethylpropionamide (5), and diethylacetamide (6)) SCMs in the intermediate region. The ΔA value for compounds 1-3 was very similar to the magnetic anisotropic energy of a single Fe(II), while the value of Δξ was predicted using the exchange interaction of Fe(II) with the neighboring Re(IV), which could be expressed as 2JSReSFe. Similar to compounds 1-3, the anisotropy energy barrier ΔA of compounds 4 and 5 was also equal to (Di - Ei)SFe(2), but the correlation energy Δξ was closely equal to 2JSReSFe(cos 98.4 - cos 180) due to the reversal of the spins on the opposite Fe(II). For compound 6, one unit cell of Re(IV)Fe(II) was regarded as a domain wall since it had two different Re(IV)-Fe(II) couplings. Thus, the Δξ of compound 6 was expressed as 4J″SRe1Fe1SRe2Fe2, where J″ was the coupling constant of the neighboring unit cells of Re1Fe1 and Re2Fe2, and ΔA was equal to the anisotropic energy barrier of one domain wall given by DRe1Fe1(S(2)Re1Fe1 - 1/4).

Understanding the magnetic anisotropy in a family of N2(3-) radical-bridged lanthanide complexes: density functional theory and ab initio calculations.

Density functional theory (DFT) and ab initio methods were used to investigate the influence of both intramolecular exchange coupling and single-ion anisotropy on the relaxation barriers of a series of N2(3-) radical-bridged lanthanide complexes [{[(Me3Si)2N]2(THF)Ln}2(µ-η(2):η(2)-N2)](-) (Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), and Er(III) (5)) reported by Long and co-workers. DFT calculations show that the exchange coupling between the lanthanide ions is very weak, but the Ln-N2(3-) coupling is strong for each complex. Moreover, the exchange couplings of Ln-N2(3-) are antiferromagnetic for Ln = Gd(III), Tb(III), Dy(III), and Ho(III) but ferromagnetic for Er(III) for the nearly orthogonal magnetic orbitals on Er(III) and N2(3-). Ab initio calculations show that both of the large magnetic anisotropy of single Tb fragment and the strong Tb-N2(3-) antiferromagnetic couplings lead to the largest energy barrier of complex 2. Although the energy barrier of a single Er fragment is the second largest, the relaxation barrier of complex 5 is only 36.0 cm(-1) due to the weak Er(III)-N2(3-) coupling. This study suggests that both intramolecular exchange coupling and single-ion anisotropy contribute greatly to the full relaxation barrier of lanthanide-based single-molecule magnets (SMMs), which expands the understanding of SMMs using only the giant-spin model.