Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 89
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Chemistry ; 30(27): e202304369, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38414107

RESUMO

Single-molecule toroics (SMTs), defined as a type of molecules with toroidal arrangement of magnetic moment associated with bi-stable non-magnetic ground states, are promising candidates for high-density information storage and the development of molecule based multiferroic materials with linear magneto-electric coupling and multiferroic behavior. The design and synthesis of SMTs by arranging the magnetic anisotropy axis in a circular pattern at the molecular level have been of great interest to scientists for last two decades since the first detection of the SMT behavior in the seminal Dy3 molecules. DyIII ion has long been the ideal candidate for constructing SMTs due to its Kramer ion nature as well as high anisotropy. Nevertheless, other LnIII ions such as TbIII and HoIII ions, as well as some paramagnetic transition metal ions, have also been used to construct many nontraditional SMTs. Therefore, we review the progress in the studies of SMTs based on the nontraditional perspective, ranging from the 3D topological to 1D&2D&3D polymeric SMTs, and 3d-4f to non Dy-based SMTs. We hope the understanding we provide about nontraditional SMTs will be helpful in designing novel SMTs.

2.
J Thromb Thrombolysis ; 57(1): 29-38, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37351822

RESUMO

BACKGROUND: VT (Ventricular Thrombus) is a serious complication of dilated cardiomyopathy (DCM). Our goal is to develop a nomogram for personalized prediction of incident VT in DCM patients. METHODS: 1267 patients (52.87 ± 11.75 years old, 73.8% male) were analyzed retrospectively from January 01, 2015, to December 31, 2020. A nomogram model for VT risk assessment was established using minimum absolute contraction and selection operator (LASSO) and multivariate logistic regression analysis, and its effectiveness was validated by internal guidance. The model was evaluated by the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA). We compared the performance in predicting VT between nomogram and CHA2DS2, CHA2DS2- VASc or ATRIA by AUC, akaike information criterion (AIC), bayesian information criterion (BIC), net reclassification index (NRI), and integrated discrimination index (IDI). RESULTS: 89 patients (7.02%) experienced VT. Multivariate logistic regression analysis revealed that age, left ventricular ejection fraction (LVEF), uric acid (UA), N-terminal precursor B-type diuretic peptide (NT-proBNP), and D-dimer (DD) were important independent predictors of VT. The nomogram model correctly separates patients with and without VT, with an optimistic C score of 0.92 (95%CI: 0.90-0.94) and good calibration (Hosmer-Lemeshow χ2 = 11.51, P = 0.12). Our model showed improved prediction of VT compared to CHA2DS2, CHA2DS2-VASc or ATRIA (all P < 0.05). CONCLUSIONS: The novel nomogram demonstrated better than presenting scores and showed an improvement in predicting VT in DCM patients.


Assuntos
Cardiomiopatia Dilatada , Cardiopatias , Trombose , Humanos , Masculino , Adulto , Pessoa de Meia-Idade , Feminino , Teorema de Bayes , Cardiomiopatia Dilatada/complicações , Cardiomiopatia Dilatada/diagnóstico , Nomogramas , Estudos Retrospectivos , Volume Sistólico , Função Ventricular Esquerda , Trombose/diagnóstico , Trombose/etiologia
3.
J Asian Nat Prod Res ; 26(7): 795-802, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38515328

RESUMO

Two new sesquiterpenoid glycosides, 8α (H)-eudesmane-1,3,11 (13)-triene-2-one -12-O-ß-D-glucopyranoside (1) and dmetelisproside B (2), together with ten known compounds (3-12) were isolated from calyces of Physalis alkekengi L. var. franchetii (Mast.) Makino (PAF). Their structures were unambiguously elucidated through HR-ESI-MS, UV, IR, and NMR spectral data. Compounds 1, 10, and 12 exhibited DPPH scavenging ability with IC50 values of 33.69 ± 6.65, 6.29 ± 0.06, and 25.66 ± 3.06 µM, respectively. Additionally, 10 and 12 demonstrated weak α-glucosidase inhibition activity with IC50 values of 250.9 ± 6.60 and 347.6 ± 2.48 µM, respectively.


Assuntos
Glicosídeos , Physalis , Sesquiterpenos , Glicosídeos/química , Glicosídeos/farmacologia , Glicosídeos/isolamento & purificação , Physalis/química , Estrutura Molecular , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Sesquiterpenos/isolamento & purificação , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/farmacologia , Inibidores de Glicosídeo Hidrolases/isolamento & purificação , Flores/química , Compostos de Bifenilo/farmacologia , Picratos/farmacologia
4.
Zhongguo Dang Dai Er Ke Za Zhi ; 26(5): 481-485, 2024 May 15.
Artigo em Zh | MEDLINE | ID: mdl-38802908

RESUMO

OBJECTIVES: To investigate the differences in clinical characteristics among children on prolonged mechanical ventilation (PMV) due to different primary diseases. METHODS: A retrospective analysis was performed on the clinical data of 59 pediatric patients requiring PMV from July 2017 to September 2022. According to the primary disease, they were divided into respiratory disease (RD) group, central nervous system (CNS) group, neuromuscular disease (NMD) group, and other disease group. The four groups were compared in terms of general information, treatment, and outcome. RESULTS: There were significant differences among the four groups in age, body weight, Pediatric Logistic Organ Dysfunction-2 (PELOD-2) score, Pediatric Risk of Mortality III (PRISM Ⅲ) score, analgesic and sedative treatment, nutrition supply, rehabilitation treatment, tracheotomy, successful ventilator weaning, and outcomes (P<0.05). Compared with the RD group, the CNS group and the other disease group had a significantly higher age and a significantly higher proportion of children receiving rehabilitation treatment, and the CNS group had a significantly higher proportion of children receiving tracheotomy (P<0.008). Compared with the other disease group, the CNS group and the NMD group had significantly lower PELOD-2 and PRISM III scores, and the CNS group had a significantly higher proportion of children with successful ventilator weaning and a significantly higher proportion of children who were improved and discharged (P<0.008). CONCLUSIONS: There are differences in clinical characteristics among children receiving PMV due to different etiologies. Most children in the RD group have a younger age, and children in the CNS group have a relatively good prognosis.


Assuntos
Doenças Neuromusculares , Respiração Artificial , Humanos , Masculino , Feminino , Estudos Retrospectivos , Pré-Escolar , Lactente , Doenças Neuromusculares/terapia , Doenças Neuromusculares/etiologia , Criança , Doenças do Sistema Nervoso Central/etiologia , Doenças do Sistema Nervoso Central/terapia , Doenças Respiratórias/terapia , Doenças Respiratórias/etiologia
5.
Proteins ; 91(8): 1140-1151, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37086011

RESUMO

The specific recognition of serum proteins by scavenger receptors is critical and fundamental in many biological processes. However, the underlying mechanism of scavenger receptor-serum protein interaction remains elusive. In this work, taking scavenger receptors class A1 (SR-A1) as an example, we systematically investigate its interaction with human serum albumin (HSA) at different states through a combination of molecular docking and all-atom molecular dynamics simulations. It is found that native HSA can moderately bind to collagen-like (CL) region or scavenger receptor cysteine-rich (SRCR) region, with both electrostatic (ELE) and van der Waals (VDW) interactions, playing important roles. After maleylation, the binding energy, particularly the ELE energy, between HSA and CL region is significantly enhanced, while the binding energy between HSA and SRCR region remains nearly unchanged. Additionally, we also observe that unfolding of the secondary structures in HSA leads to a larger contact surface area between denatured HSA and CL region, but has little impact on the HSA-SRCR region interaction. Therefore, similar to maleylated HSA, denatured HSA is also more likely to bind to the CL region of SR-A1.


Assuntos
Albumina Sérica Humana , Humanos , Simulação de Acoplamento Molecular , Sítios de Ligação , Espectrometria de Fluorescência , Termodinâmica , Albumina Sérica Humana/metabolismo , Receptores Depuradores/metabolismo , Ligação Proteica , Dicroísmo Circular
6.
J Comput Chem ; 44(5): 677-686, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36408852

RESUMO

The ability to accurately and rapidly evaluate the intermolecular many-body polarization effect of the water system is very important for computer simulations of biomolecule in aqueous. In this paper, a scheme is proposed based on the polarizable dipole-dipole interaction model and used to rapidly estimate the intermolecular many-body polarization effect in water clusters. We use a bond-dipole-based polarization function to evaluate the polarization energy. We regard two OH bonds of a water molecule as two bond-dipoles and set the permanent OH bond-dipole moment of a water molecule to be 1.51 Debye. We estimate the induced OH bond-dipole moment via a simple formula in which only one correction factor is needed. This scheme is then applied to tens of water clusters to calculate the three- and four-body interaction energies. The three-body interaction energies of 93 water clusters produced by our scheme are compared with those produced by the counterpoise-corrected CCSD(T)/aug-cc-pVDZ, MP2/aug-cc-pVDZ, M06-2X/jul-cc-pVTZ methods, by the AMOEBApro13, iAMOEBA, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The four-body interaction energies of 47 water clusters yielded by our scheme are compared with those yielded by the counterpoise-corrected MP2/aug-cc-pVDZ and M06-2X/ jul-cc-pVTZ methods, by the AMOEBApro13, AMOEBA+, AMOEBA+(CF) methods, and by the MB-pol method. The comparison results show that the scheme proposed in this paper can reproduce the counterpoise-corrected CCSD(T)/aug-cc-pVDZ three-body interaction energies and reproduce the counterpoise-corrected MP2/aug-cc-pVDZ four-body interaction energies both accurately and efficiently. We anticipate the scheme proposed here can be useful for computer simulations of liquid water and aqueous solutions.


Assuntos
Água , Termodinâmica , Simulação por Computador
7.
Chemistry ; 29(5): e202202896, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36326186

RESUMO

Two pairs of chiral end-on azido-bridged dinuclear hexaazamacrocycles, [Dy2 (LN6 R/S )2 (N3 )2 Cl2 ](BPh4 )2 (1R/1S) and [Dy2 (LN6 R/S )2 (N3 )4 ]Cl2 (2R/2S) (LN6 R/S is hexaazamacrocyclic neutral Schiff base ligand derived from 2,6-diformylpyridine and (1R, 2R)/(1S, 2S)-diaminocyclohexane), were constructed by adjusting the molar ratio of sodium azide to Dy(III) macrocycle precursor. Structural analyses reveal that all Dy(III) centers in complexes 1R/1S and 2R/2S are nine-coordinate with hula-loop coordination geometry, and the differences between 1R/1S and 2R/2S are the terminal coordination anion and counter anion. Magnetic studies indicate that complex 2S displays typical SMM behaviors under a zero dc field, whereas 1S just shows slow relaxation of magnetization resulting from a relatively weak axial crystal field. Significantly, complex 2R/2S represents the first homochiral all-nitrogen-coordinated lanthanide single-molecule magnet.


Assuntos
Elementos da Série dos Lantanídeos , Imãs , Disprósio , Nitrogênio
8.
J Xray Sci Technol ; 31(6): 1333-1340, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37840466

RESUMO

OBJECTIVE: To explore the value of applying computed tomography (CT) radiomics based on different CT-enhanced phases to determine the immunotherapeutic efficacy of non-small cell lung cancer (NSCLC). METHODS: 106 patients with NSCLC who underwent immunotherapy are randomly divided into training (74) and validation (32) groups. CT-enhanced arterial and venous phase images of patients before treatment are collected. Region-of-interest (ROI) is segmented on the CT-enhanced images, and the radiomic features are extracted. One-way analysis of variance and least absolute shrinkage and selection operator (LASSO) are used to screen the optimal radiomics features and analyze the association between radiomics features and immunotherapy efficacy. The area under receiver-operated characteristic curves (AUC) along with the sensitivity and specificity are computed to evaluate diagnostic effectiveness. RESULTS: LASSO regression analysis screens and selects 6 and 8 optimal features in the arterial and venous phases images, respectively. Applying to the training group, AUCs based on CT-enhanced arterial and venous phase images are 0.867 (95% CI:0.82-0.94) and 0.880 (95% CI:0.86-0.91) with the sensitivities of 73.91% and 76.19%, and specificities of 66.67% and 72.19%, respectively, while in validation group, AUCs of the arterial and venous phase images are 0.732 (95% CI:0.71-0.78) and 0.832 (95% CI:0.78-0.91) with sensitivities of 75.00% and 76.00%, and specificities of 73.07% and 75.00%, respectively. There are no significant differences between AUC values computed from arterial phases and venous phases images in both training and validation groups (P < 0.05). CONCLUSION: The optimally selected radiomics features computed from CT-enhanced different-phase images can provide new imaging marks to evaluate efficacy of the targeted therapy in NSCLC with a high diagnostic value.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma Pulmonar de Células não Pequenas/terapia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/terapia , Tomografia Computadorizada por Raios X , Imunoterapia , Área Sob a Curva , Estudos Retrospectivos
9.
Zhongguo Zhong Yao Za Zhi ; 48(22): 5985-5992, 2023 Nov.
Artigo em Zh | MEDLINE | ID: mdl-38114204

RESUMO

Vaccination is an effective method for preventing influenza, and adjuvants can enhance the immune response intensity and persistence of influenza vaccines. However, there are currently shortcomings in clinical adjuvant approvals, ineffectiveness against weak antigens, and a tendency to cause headaches. Therefore, the development of safe and effective novel adjuvants for influenza vaccines is particularly important to enhance vaccine immunogenicity and safety. Given the wide range of sources, high safety, and biodegradability of traditional Chinese medicine(TCM), some studies have described it as a vaccine adjuvant. This article reviewed the current status and challenges of influenza vaccine adjuvants, summarized the types of TCM adjuvants, the safety and immunomodulatory effects of natural active ingredients from TCM combined with influenza vaccines, the role of TCM adjuvants in antigen storage, antigen presentation capability, immune cells and cytokines, and immune responses, and analyzed the advantages and disadvantages of TCM adjuvants compared with small molecule adjuvants, with the aim of promoting the clinical development and commercialization of TCM adjuvants for influenza vaccines.


Assuntos
Vacinas contra Influenza , Influenza Humana , Humanos , Adjuvantes Imunológicos/farmacologia , Medicina Tradicional Chinesa , Influenza Humana/prevenção & controle , Adjuvantes Farmacêuticos
10.
Langmuir ; 38(45): 13972-13982, 2022 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-36318181

RESUMO

The spread of coronavirus disease 2019 caused by SARS-CoV-2 and its variants has become a global health crisis. Although there were many attempts to use nanomaterials-based devices to fight against SARS-CoV-2, it still remains elusive as to how the nanomaterials interact with SARS-CoV-2 and affect its biofunctions. Here, taking the graphene nanosheet (GN) as the model nanomaterial, we investigate its interaction with the spike protein in both WT and Omicron by molecular simulations. In the closed state, the GN can insert into the region between the receptor binding domain (RBD) and the N-terminal domain (NTD) in both wild type (WT) and Omicron, which keeps the RBD in the down conformation. In the open state, the GN can hamper the binding of up RBD to ACE2 in WT, but it has little impact on up RBD and, even worse, stimulates the down-to-up transition of down RBDs in Omicron. Moreover, the GN can insert in the vicinity of the fusion peptide in both WT and Omicron and prevents the detachment of S1 from the whole spike protein. The present study reveals the effect of the SARS-CoV-2 variant on the nanomaterial-spike protein interaction, which informs prospective efforts to design functional nanomaterials against SARS-CoV-2.


Assuntos
COVID-19 , Grafite , Humanos , Enzima de Conversão de Angiotensina 2 , Peptidil Dipeptidase A/metabolismo , Estudos Prospectivos , Ligação Proteica , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo , Nanoestruturas
11.
Beilstein J Org Chem ; 18: 374-380, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35495775

RESUMO

Four new polyhydroxylated steroids lobophysterols E-H (1-4), together with three known compounds (5-7), were isolated from the soft coral Lobophytum pauciflorum collected at Xisha Island, China. The structures of the new compounds were elucidated by extensive spectroscopic analysis and comparison with NMR data of structurally related compounds reported in the literature. The absolute configuration of 1-3 was determined by X-ray diffraction. All the compounds have assessed the cytotoxicity against HL-60, K562, and Hela cells. Compound 1 showed weak cytotoxicity against K562 cells with an IC50 value of 19.03 µM. In addition, compound 1 also showed a moderate anti-inflammatory effect in zebrafish.

12.
J Am Chem Soc ; 143(27): 10077-10082, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34181405

RESUMO

Design and synthesis of air-stable and easily tailored high-performance single-molecule magnets (SMMs) are of great significance toward the implementation of SMMs in molecular-based magneto-electronic devices. Here, by introducing electron-withdrawing fluorinated substituents on equatorial ligand, two chiral Dy(III) macrocyclic complexes, RRRR-Dy-D6hF12 (1) and SSSS-Dy-D6hF12 (2), with a record anisotropy barrier exceeding 1800 K and the longest relaxation time approaching 2500 s at 2.0 K for all known air-stable SMMs, were obtained. The nearly perfect axiality of the ground Kramers doublet (KD) enables the open hysteresis loops up to 20 K in the magnetically diluted sample. It is notable that they are structurally rigid with high thermal stability and the apical ligand can be tailored to carry proper surface-binding groups. This finding not only improves the magnetic properties for air-stable SMMs but also provides a new avenue for deposition of SMMs on surfaces.

13.
Langmuir ; 35(39): 12851-12857, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31474103

RESUMO

The well control over the cell-nanoparticle interaction can be of great importance and necessity for different biomedical applications. In this work, we propose a new and simple way (i.e., polymeric tether) to tuning the interaction between nanoparticles and cell membranes by dissipative particle dynamics simulations. It is found that the linked nanoparticles (via polymeric tether) can show some cooperation during the cellular uptake and thereby have a higher wrapping degree than the single nanoparticle. The effect of the property of the polymer on the wrapping is also investigated, and it is found that the length, rigidity, and hydrophobicity of the polymer play an important role. More interestingly, the uptake of linked nanoparticles could be adjusted to the firm adhesion via two rigid polymeric tethers. The present study may provide some useful guidelines for novel design of functional nanomaterials in the experiments.


Assuntos
Membrana Celular/química , Nanopartículas/química , Polímeros/química , Éteres/química , Modelos Moleculares , Conformação Molecular
14.
Inorg Chem ; 58(9): 5715-5724, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-30969114

RESUMO

Six tetranuclear DyIII complexes [Dy4(L)2(CH3OH)3(NO3)3]·3NO3·2H2O (1a), [Dy4(L)2(CH3OH)2(SCN)4(OCH3)2]·2CH3OH·2H2O (1b), {[Dy4(L)2(CH3OH)(SCN)6(CH3CN)]·3CH3OH·4CH3CN}2 (2a), [Dy4(L)2(CH3OH)2(SCN)6]·6CH3OH·2H2O (2b), [Dy4(L)2(CH3OH)2(SCN)4(OCH3)2]·5CH3OH·2H2O (3a), and [Dy4(L)2(CH3OH)(SCN)5(H2O)2]·SCN·4CH3OH·2H2O (3b) were structurally and magnetically characterized. The Dy1/Dy2 centers in these complexes are eight-coordinate and submitted to pseudo- D4d symmetry environments. It is noteworthy that the modulation of coordination terminal around Dy1/Dy2 centers induces distinct magnetic relaxation processes, switching from single relaxation (1b) to two-step relaxation (2b). All complexes show significant zero-field single-molecule magnet (SMM) properties with the exception of 3b, which only features the slow magnetic relaxation behavior under a zero dc field. Ab initio calculations substantiate that the excellent SMM property of complex 1b should mainly profit from strong ferromagnetic interactions between the individual DyIII ions, while different single-ion magnetism results in better SMM property of complex 3a than that of 3b.

15.
Inorg Chem ; 58(18): 11903-11911, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31192594

RESUMO

Four hexanuclear circular helicates, {[Dy6L6(DMF)12]·6CF3SO3·12DMF}2 (1Dy), {[Gd6L6(DMF)12]·6CF3SO3·12DMF}2 (1Gd), [Dy6L6(DMF)10(H2O)2]·6ClO4·4H2O·10DMF (2Dy), and [Gd6L6(DMF)12]·6ClO4·2H2O·10DMF (2Gd), where DMF = N,N-dimethylformamide, were synthesized by employing a glutaratedihydrazide-bridged bis(3-methoxysalicylaldehyde) ligand (H2L) and characterized structurally and magnetically. Direct-current magnetic susceptibility studies indicated predominant weak antiferromagnetic exchange interactions among gadolinium analogues, which were quantified using the PHI software, giving J = -0.003 cm-1 with g = 2.00 for 1Gd and J = -0.001 cm-1 with g = 2.02 for 2Gd. Alternating-current magnetic susceptibility measurements indicated that complexes 1Dy and 2Dy show slow relaxation of magnetization behavior, further supported by theoretical calculations that also highlighted the toroidal arrangement of the magnetic moments.

16.
Zhongguo Zhong Yao Za Zhi ; 43(23): 4582-4586, 2018 Dec.
Artigo em Zh | MEDLINE | ID: mdl-30717545

RESUMO

A pair of species-specific primer (GZG1/GZG2) based on COⅠ sequence regions for identification of Gekko chinensis were designed. A fluorescent quantitative PCR method was established to identify and quantify G. chinensis from Jinlong Capsules Formula. A standard curve for quantitative analysis of G. chinensis was established (the standard curve equation: y=-3.012 7x+34.501, y is Ct value, x is lg N, N is the copies of COⅠ fragment from G. chinensis). Samples included G. chinensis appeared amplification, while falsify group (not included G. chinensis) and negative control did not have amplification products. The copy number of COⅠ region of G. chinensis was respectively 11.511×106, 6.416×106, 2.553×106 copies/µL in all quality goods, quality goods-adulterants 1:1, quality goods-adulterants 1:4. The results accorded with proportion of adding amount roughly. This study can provide a new strategy for quality control of Chinese patent medicine containing animal drug ingredients.


Assuntos
Medicamentos de Ervas Chinesas , Cápsulas , Reação em Cadeia da Polimerase
17.
Inorg Chem ; 56(7): 4104-4111, 2017 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-28290670

RESUMO

A series 1.Ln of tetranuclear lanthanide clusters [Ln4(µ4-O)L2(PhCOO)6]·solvent (Ln = Gd (1.Gd), Dy (1.Dy), Ho (1.Ho)) and octanuclear lanthanide Ln4 cluster pairs 2.Ln [Ln8(µ3-OH)4(CO3)2L4(PhCOO)8]·solvent (Ln = Gd (2.Gd), Dy (2.Dy), Tb (2.Tb)) were assembled by using a bi-Schiff-based ligand H2L and characterized structurally and magnetically. Interestingly, the octanuclear Ln4 cluster pairs 2.Ln are proposed to be assembled from the tetranuclear clusters 1.Ln through the uptake of CO2 from air in a more basic media. X-ray structural analyses approved the possible evolution mechanism. Magnetic studies reveal the coexistence of ferro- and anti-ferromagnetic interaction in 1.Gd and 2.Gd by simulating the direct-current magnetic susceptibility and indicate the CO32- bridges produce weak ferromagnetic interaction in 2.Gd rather than anti-ferromagnetic interaction by benzoate bridges in 1.Gd. The magnitude of the magnetocaloric effect has been examined and shows that complex 2.Gd exhibits larger magnetocaloric effect than 1.Gd, which could be probably ascribed to the weak ferromagnetic interaction produced by the CO32- bridges.

18.
Inorg Chem ; 56(18): 11211-11219, 2017 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-28853556

RESUMO

A series of mononuclear DyIII complexes with the general formula [DyLz2(salicylaldehyde)2]·X·solvent (Lz = 6-pyridin-2-yl[1,3,5]triazine-2,4-diamine; X = OH- (1·OH), Cl- (2·Cl), Br- (3·Br)) have been synthesized using mixed salicylaldehyde/pyridinyl-triazine ligands and discriminative counteranions. The DyIII ion in these three complexes resides in a similar D4d coordination geometry with counteranions perturbing the coordination environment and bond lengths and angles in the lattice. Magnetostructural studies reveal that the asymmetric distribution of salicylaldehyde/pyridinyl-triazine ligands and the presence of discriminative counteranions result in the coexistence of large anisotropy and quantum tunneling of magnetization. The magnetic anisotropy is dominated by the axial ligand field with short Dy-Osali distances and large ∠Osali-Dy-Osali angles, while the quantum tunneling relaxation is probably dictated by the π-π stacking of the Lz ligands, which induces an axial constriction of the coordinating plane. Ab initio calculations substantiate the diversity of the magnetic behaviors in these complexes and highlight the importance of axial ligand field with short Dy-Osali distances, large ∠Osali-Dy-Osali angles and less ligand stacking in these pseudo-D4d-symmetrical single-molecule magnets.

19.
Inorg Chem ; 55(11): 5514-9, 2016 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-27195580

RESUMO

A series of mixed metal 3d-4f gridlike structures, [Dy4(H2L')4Zn4(SCN)4] (1) and [Dy4(H2L')4Mx(SCN)8] (Mx = Co3 (2); Mx = Cu5 (3)), showing Chinese hieroglyph like [2 × 2], [3 × 2], and [3 × 3] matrixes, were assembled and magnetically characterized. Remarkably, the empty cage constructed by the oblique organic ligands and SCN(-) ions in complex 1 were filled with the large inorganic ions [Co3(SCN)4](2+) and [Cu5(SCN)4](6+) in complexes 2 and 3, respectively, forming the first [3 × 2] and [3 × 3] 3d-4f gridlike structures. Additionally, magnetic studies show that complex 1 exhibits field-induced SMM behavior and double magnetic relaxation, while complexes 2 and 3 display typical SMM behavior at zero applied field.

20.
Angew Chem Int Ed Engl ; 55(50): 15574-15578, 2016 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-27860086

RESUMO

The self-assembly of three giant hexagonal 3d-4f metallocycles with inner diameters of 16.4, 16.5, and 16.4 Å, is described. Hexagonal metallocycles were stacked along the crystallographic c axis, producing unique hexagonal macroscopic tubular single crystals. The assembly mechanism of the tubular crystals was investigated. Remarkably, all three hexagonal metallocycles show typical single-molecule magnet behavior, benefiting from the ferromagnetic couplings between the 3d and 4f ions.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA