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1.
Environ Sci Technol ; 58(17): 7480-7492, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38639388

RESUMO

Microbial transformation of per- and polyfluoroalkyl substances (PFAS), including fluorotelomer-derived PFAS, by native microbial communities in the environment has been widely documented. However, few studies have identified the key microorganisms and their roles during the PFAS biotransformation processes. This study was undertaken to gain more insight into the structure and function of soil microbial communities that are relevant to PFAS biotransformation. We collected 16S rRNA gene sequencing data from 8:2 fluorotelomer alcohol and 6:2 fluorotelomer sulfonate biotransformation studies conducted in soil microcosms under various redox conditions. Through co-occurrence network analysis, several genera, including Variovorax, Rhodococcus, and Cupriavidus, were found to likely play important roles in the biotransformation of fluorotelomers. Additionally, a metagenomic prediction approach (PICRUSt2) identified functional genes, including 6-oxocyclohex-1-ene-carbonyl-CoA hydrolase, cyclohexa-1,5-dienecarbonyl-CoA hydratase, and a fluoride-proton antiporter gene, that may be involved in defluorination. This study pioneers the application of these bioinformatics tools in the analysis of PFAS biotransformation-related sequencing data. Our findings serve as a foundational reference for investigating enzymatic mechanisms of microbial defluorination that may facilitate the development of efficient microbial consortia and/or pure microbial strains for PFAS biotransformation.


Assuntos
Biotransformação , Microbiologia do Solo , RNA Ribossômico 16S/genética , Solo/química , Poluentes do Solo/metabolismo , Fluorocarbonos/metabolismo
2.
Environ Sci Technol ; 56(19): 13728-13739, 2022 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-36127292

RESUMO

The environmental fate of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foams (AFFFs) remains largely unknown, especially under the conditions representative of natural subsurface systems. In this study, the biotransformation of 8:2 fluorotelomer alcohol (8:2 FTOH), a component of new-generation AFFF formulations and a byproduct in fluorotelomer-based AFFFs, was investigated under nitrate-, iron-, and sulfate-reducing conditions in microcosms prepared with AFFF-impacted soils. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high-resolution mass spectrometry (HRMS) were employed to identify biotransformation products. The biotransformation was much slower under sulfate- and iron-reducing conditions with >60 mol % of initial 8:2 FTOH remaining after ∼400 days compared to a half-life ranging from 12.5 to 36.5 days under nitrate-reducing conditions. Transformation products 8:2 fluorotelomer saturated and unsaturated carboxylic acids (8:2 FTCA and 8:2 FTUA) were detected under all redox conditions, while 7:2 secondary fluorotelomer alcohol (7:2 sFTOH) and perfluorooctanoic acid (PFOA) were only observed as transformation products under nitrate-reducing conditions. In addition, 1H-perfluoroheptane (F(CF2)6CF2H) and 3-F-7:3 acid (F(CF2)7CFHCH2COOH) were identified for the first time during 8:2 FTOH biotransformation. Comprehensive biotransformation pathways for 8:2 FTOH are presented, which highlight the importance of accounting for redox condition and the related microbial community in the assessment of PFAS transformations in natural environments.


Assuntos
Fluorocarbonos , Álcoois/metabolismo , Biotransformação , Cromatografia Líquida , Ferro , Nitratos , Compostos Orgânicos , Solo , Sulfatos , Espectrometria de Massas em Tandem , Água
3.
Inorg Chem ; 57(14): 8065-8077, 2018 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-29965732

RESUMO

A series of Salen-type Zn(II)-Dy(III) complexes [L1Zn(II)ClDy(III)(acac)2]·H2O (1), [L1Zn(II)BrDy(III)(acac)2]·H2O (2), [L1Zn(II)(H2O)Dy(III)(acac)2]·CH2Cl2·PF6 (3), [L2Zn(II)(H2O)Dy(III)(acac)2]·PF6 (4), and Co(III)-Dy(III) complexes [L1Co(III)Br2Dy(III)(acac)2]·CH2Cl2 (5), [L2Co(III)Cl2Dy(III)(acac)Cl(MeO)] (6), [L2Co(III)Cl2Dy(III)(acac)Cl(H2O)] (7), and [L2Co(III)Cl2Dy(III)(NO3)2(MeO)] (8) heterobinuclear single-molecule magnets (SMMs) were synthesized and magnetically characterized. These complexes were constructed by incorporating diamagnetic Zn(II) and Co(III) ions with acetylacetone (acac) and compartmental Schiff-base ligands (H2L1 = N, N'-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine; H2L2 = N, N'-bis(2-oxy-3-methoxybenzylidene)-1,2-diaminocyclohexane). In the Zn(II)-Dy(III) (1-4) system, the coordination environments of the Dy(III) ions are nearly identical, but the apical coordination atom to the Zn(II) ion is different. Complexes 1, 2, and 4 displayed no magnetic relaxation in the absence of external magnetic field, but complex 3 displayed more pronounced SMM behavior with a relaxation energy barrier Ueff/ kB 38 K and magnetic hysteresis at 1.8 K. The SMM performances of 5, 6, and 7 were enhanced significantly by incorporating an octahedral Co(III) instead of square-pyramidal Zn(II) and replacing one of acac- group around Dy(III) ion by a neutral O atom, displaying Ueff of 167, 118, and 75 K as well as magnetic hysteresis up to 3.5 K. These studies indicated that the remote diamagnetic Zn(II) and Co(III) ions played a key role, and the SMM properties were very strongly related to the special coordination atoms configuration around Dy(III) ion. When this coordination configuration around was broken as 8 exhibited, however, it resulted in a dramatically decreased SMM performance. From this work, the key factors that significantly affect the SMM performance of these heteronuclear Zn(II)/Co(III)-Dy(III) SMMs are unambiguously presented.

4.
Molecules ; 21(10)2016 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-27754383

RESUMO

Paeonia is the single genus of ca. 33 known species in the family Paeoniaceae, found in Asia, Europe and Western North America. Up to now, more than 180 compounds have been isolated from nine species of the genus Paeonia, including terpenes, phenols, flavonoids, essential oil and tannins. Terpenes, the most abundant naturally occurring compounds, which accounted for about 57% and occurred in almost every species, are responsible for the observed in vivo and in vitro biological activities. This paper aims to give a comprehensive overview of the recent phytochemical and pharmacological knowledge of the terpenes from Paeonia plants, and enlighten further drug discovery research.


Assuntos
Paeonia/química , Terpenos/química , Terpenos/farmacologia , Anestésicos/química , Anestésicos/farmacologia , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Anticoagulantes/química , Anticoagulantes/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Descoberta de Drogas , Humanos , Hipnóticos e Sedativos/química , Hipnóticos e Sedativos/farmacologia , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/farmacologia
5.
Inorg Chem ; 54(1): 221-8, 2015 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-25495352

RESUMO

A series of rigid hexadentate salen-type (H2L) ytterbium complexes, namely, [Yb2L3(CH3OH)]·3CH3CN (1), [Yb2LL'L″(CH3OH)(H2O)2](ClO4)2·CH3OH·H2O (2), [Yb2L(OAc)4(CH3OH)2]·2CH3OH (3), and {[Yb2L(OAc)4]·3H2O}n (4) (H2L = N,N'-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine, HL' = 2-(2'-hydroxy-3'-methyloxy-phenyl)benzimidazole and HL" = 3-methoxysalicylaldehyde) have been synthesized by reactions of H2L with multifarious Yb(3+) salts. X-ray crystallographic analyses demonstrate that complex 1 is of a triple-decker sandwich-type Yb2L3 structure with a ratio of H2L/Yb = 3:2, 2 and 3 possess the unique Yb2 core with a ratio of H2L/Yb = 2:2 and 1:2, respectively, 4 exhibits one dimensional coordination polymers in which the polymeric structures are formed by acetate (OAc(-)) groups. All complexes 1-4 exhibit near-IR luminescence, which can be rationalized on the basis of the disparate structural effects. The magnetic analysis unveils that all complexes 1-4 are of field-induced single-molecule magnet behavior with the energy barriers (Ueff/kB) of 14.5, 2.0, 9.5, and 2.4 K at 3 kOe direct current fields, respectively.

6.
Sci Total Environ ; 927: 171883, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38531439

RESUMO

Aqueous film-forming foams (AFFFs) have been extensively used for extinguishing hydrocarbon-fuel fires at military sites, airports, and fire-training areas. Despite being a significant source of per- and polyfluoroalkyl substances (PFAS), our understanding of PFAS occurrence in AFFF formulations and AFFF-impacted environments is limited, as is the impact of microbial transformation on the environment fate of AFFF-derived PFAS. This literature review compiles PFAS concentrations in electrochemical fluorination (ECF)- and fluorotelomer (FT)-based AFFFs and provides an overview of PFAS occurrence in AFFF-impacted environments. Our analysis reveals that AFFF use is a predominant point source of PFAS contamination, including primary precursors (polyfluoroalkyl substances as AFFF components), secondary precursors (polyfluoroalkyl transformation products of primary precursors), and perfluoroalkyl acids (PFAAs). Moreover, there are discrepancies between PFAS concentration profiles in AFFFs and those measured in AFFF-impacted media. For example, primary precursors constitute 52.6 % and 99.5 % of PFAS mass in ECF- and FT-based AFFFs, respectively, whereas they represent only 0.7 % total mass in AFFF-impacted groundwater. Conversely, secondary precursors, which constitute <1 % of PFAS in AFFFs, represent 4.0-27.8 % of PFAS in AFFF-impacted environments. The observed differences in PFAS levels between AFFFs and environmental samples are likely due to in-situ biotransformation processes. Biotransformation rates and pathways reported for AFFF-derived primary and secondary precursors varied among different classes of precursors, consistent with the PFAS occurrence in AFFF-impacted environments. For example, readily biodegradable primary precursors, N-dimethyl ammonio propyl perfluoroalkane sulfonamide (AmPr-FASA) and n:2 fluorotelomer thioether amido sulfonate (n:2 FtTAoS), were rarely detected in AFFF-impacted environments. In contrast, key secondary precursors, perfluoroalkane sulfonamides (FASAs) and n:2 fluorotelomer sulfonate (n:2 FTS), were widely detected, which was attributed to their resistance to biotransformation. Key knowledge gaps and future research priorities are presented to better understand the occurrence, fate, and transport of AFFF-derived PFAS in the environment and to design more effective remediation strategies.

7.
Water Res ; 249: 120941, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38070347

RESUMO

Although 6:2 fluorotelomer sulfonate (6:2 FTS) is a common ingredient in aqueous film-forming foam (AFFF) formulations, its environmental fate at AFFF-impacted sites remains poorly understood. This study investigated the biotransformation of 6:2 FTS in microcosms prepared with soils collected from two AFFF-impacted sites; the former Loring Air Force Base (AFB) and Robins AFB. The half-life of 6:2 FTS in Loring soil was 43.3 days; while >60 mol% of initially spiked 6:2 FTS remained in Robins soil microcosms after a 224-day incubation. Differences in initial sulfate concentrations and the depletion of sulfate over the incubation likely contributed to the different 6:2 FTS biotransformation rates between the two soils. At day 224, stable transformation products, i.e., C4C7 perfluoroalkyl carboxylates, were formed with combined molar yields of 13.8 mol% and 1.2 mol% in Loring and Robins soils, respectively. Based on all detected transformation products, the biotransformation pathways of 6:2 FTS in the two soils were proposed. Microbial community analysis suggests that Desulfobacterota microorganisms may promote 6:2 FTS biotransformation via more efficient desulfonation. In addition, species from the genus Sphingomonas, which exhibited higher tolerance to elevated concentrations of 6:2 FTS and its biotransformation products, are likely to have contributed to 6:2 FTS biotransformation. This study demonstrates the potential role of biotransformation processes on the fate of 6:2 FTS at AFFF-impacted sites and highlights the need to characterize site biogeochemical properties for improved assessment of 6:2 FTS biotransformation behavior.


Assuntos
Fluorocarbonos , Poluentes Químicos da Água , Solo/química , Fluorocarbonos/análise , Biotransformação , Alcanossulfonatos/análise , Alcanossulfonatos/metabolismo , Água/análise , Sulfatos , Poluentes Químicos da Água/análise
8.
Water Res ; 252: 121146, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38306753

RESUMO

Nearly all per- and polyfluoroalkyl substances (PFAS) biotransformation studies reported to date have been limited to laboratory-scale batch reactors. The fate and transport of PFAS in systems that more closely represent field conditions, i.e., in saturated porous media under flowing conditions, remain largely unexplored. This study investigated the biotransformation of 6:2 fluorotelomer sulfonate (6:2 FTS), a representative PFAS of widespread environmental occurrence, in one-dimensional water-saturated flow-through columns packed with soil obtained from a PFAS-contaminated site. The 305-day column experiments demonstrated that 6:2 FTS biotransformation was rate-limited, where a decrease in pore-water velocity from 3.7 to 2.4 cm/day, resulted in a 21.7-26.1 % decrease in effluent concentrations of 6:2 FTS and higher yields (1.0-1.4 mol% vs. 0.3 mol%) of late-stage biotransformation products (C4C7 perfluoroalkyl carboxylates). Flow interruptions (2 and 7 days) were found to enhance 6:2 FTS biotransformation during the 6-7 pore volumes following flow resumption. Model-fitted 6:2 FTS column biotransformation rates (0.039-0.041 cmw3/gs/d) were ∼3.5 times smaller than those observed in microcosms (0.137 cmw3/gs/d). Additionally, during column experiments, planktonic microbial communities remained relatively stable, whereas the composition of the attached microbial communities shifted along the flow path, which may have been attributed to oxygen availability and the toxicity of 6:2 FTS and associated biotransformation products. Genus Pseudomonas dominated in planktonic microbial communities, while in the attached microbial communities, Rhodococcus decreased and Pelotomaculum increased along the flow path, suggesting their potential involvement in early- and late-stage 6:2 FTS biotransformation, respectively. Overall, this study highlights the importance of incorporating realistic environmental conditions into experimental systems to obtain a more representative assessment of in-situ PFAS biotransformation.


Assuntos
Fluorocarbonos , Microbiota , Poluentes Químicos da Água , Fluorocarbonos/análise , Biotransformação , Alcanossulfonatos/metabolismo , Água , Poluentes Químicos da Água/análise
9.
Am J Cardiol ; 203: 193-202, 2023 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-37499599

RESUMO

Intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) has been reported to significantly reduce major adverse cardiac events (MACEs) compared with angiography-guided PCI. We aimed to explore whether there were racial differences regarding the beneficial effects of IVUS-guided PCI. Randomized controlled trials for comparison of clinical outcomes between IVUS-guided and angiography-guided PCI were retrieved from PubMed, Web of Science, Embase, and the Cochrane Library from inception to March 15, 2023. The clinical outcomes included MACE, all-cause mortality, myocardial infarction (MI), target vessel revascularization (TVR), target lesion revascularization (TLR), and stent thrombosis (ST). Finally, 18 randomized controlled trials were included in this study (8 in East Asian patients and 10 in Western patients). Results showed that IVUS-guided PCI was associated with a significant reduction of MACE, TVR, TLR, and ST, but not all-cause mortality and MI in both East Asian and Western patients. The reduction of MACE was more significant in East Asian patients (odds ratio [OR] 0.57, 95% confidence interval [CI] 0.46 to 0.70) than that in Western patients (OR 0.83, 95% CI 0.67 to 1.02). Meta-regression analysis revealed that the country the study was performed in (East Asian vs Western countries) was associated with significant heterogeneity between groups, suggesting that racial differences existed (p = 0.033). In conclusion, IVUS-guided PCI was associated with a lower risk of MACE, TLR, TVR, and ST, but not all-cause mortality and MI in both East Asians and Westerners. East Asians benefited more than Westerners upon using IVUS-guided PCI in reducing MACE, suggesting that racial differences do exist between different imaging methods. Larger-sample studies are warranted for further clarification of our findings.


Assuntos
Doença da Artéria Coronariana , Stents Farmacológicos , Infarto do Miocárdio , Intervenção Coronária Percutânea , Trombose , Humanos , Doença da Artéria Coronariana/diagnóstico , Doença da Artéria Coronariana/cirurgia , Doença da Artéria Coronariana/complicações , Intervenção Coronária Percutânea/métodos , Angiografia Coronária/métodos , Fatores Raciais , Stents Farmacológicos/efeitos adversos , Resultado do Tratamento , Ultrassonografia de Intervenção/métodos , Infarto do Miocárdio/cirurgia , Infarto do Miocárdio/etiologia , Trombose/etiologia , Ensaios Clínicos Controlados Aleatórios como Assunto
10.
J Hazard Mater ; 446: 130629, 2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36630879

RESUMO

Production of 8:2 fluorotelomer alcohol (8:2 FTOH) for industrial and consumer products, including aqueous film-forming foams (AFFFs) used for firefighting, has resulted in its widespread occurrence in the environment. However, the fate of 8:2 FTOH at AFFF-impacted sites remains largely unknown. Using AFFF-impacted soils from two United States Air Force Bases, microcosm experiments evaluated the aerobic biotransformation of 8:2 FTOH (extent and byproduct formation) and the dose-response on microbial communities due to 8:2 FTOH exposure. Despite different microbial communities, rapid transformation of 8:2 FTOH was observed during a 90-day incubation in the two soils, and 7:2 secondary fluorotelomer alcohol (7:2 sFTOH) and perfluorooctanoic acid (PFOA) were detected as major transformation products. Novel transformation products, including perfluoroalkane-like compounds (1H-perfluoroheptane, 1H-perfluorohexane, and perfluoroheptanal) were identified by liquid chromatography-high resolution mass spectrometry (LC-HRMS) and used to develop aerobic 8:2 FTOH biotransformation pathways. Microbial community analysis suggests that species from genus Sphingomonas are potential 8:2 FTOH degraders based on increased abundance in both soils after exposure, and the genus Afipia may be more tolerant to and/or involved in the transformation of 8:2 FTOH at elevated concentrations. These findings demonstrate the potential role of biological processes on PFAS fate at AFFF-impacted sites through fluorotelomer biotransformation.


Assuntos
Fluorocarbonos , Microbiota , Fluorocarbonos/análise , Biotransformação , Hidrocarbonetos Fluorados/análise , Cromatografia Líquida
11.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 3): m251, 2012 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-22412409

RESUMO

The title complex, [Er(C(32)H(16)N(8))(C(5)H(7)O(2))(C(12)H(8)N(2))], possesses a mirror plane and the asymmetric unit is half of the mol-ecule. The Er(III) cation, lying on the mirror plane, is eight-coordinated by two O atoms from acetyl-acetone, two N (N(phen)) atoms from 1,10-phenanthroline and four isoindole N (N(iso)) atoms from the phthalocyanine ligand in an anti-prismatic geometry. The Er-N distances are in the range 2.376 (5)-2.529 (4) Šand the Er-O distance is 2.272 (3) Å. Notably, the Er-N(iso) bonds are shorter than the Er-N(phen) bonds, but longer than the Er-O bonds.

12.
Artigo em Inglês | MEDLINE | ID: mdl-22259359

RESUMO

In the title complex, [Co(C(22)H(18)N(2)O(4))(CN)(H(2)O)]·0.5CH(3)CN, the Co(III) cation is N,N',O,O'-chelated by a 6,6'-dimeth-oxy-2,2'-[1,2-phenyl-enebis(nitrilo-methanylyl-idene)]diphenolate dianion, and is further coordinated by a cyanide anion and a water mol-ecule in the axial sites, completing a distorted octa-hedral coordination geometry. In the crystal, pairs of bifurcated O-H⋯(O,O) hydrogen bonds link adjacent mol-ecules, forming centrosymmetric dimers. The acetonitrile solvent mol-ecule shows 0.5 occupancy.

13.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 3): o651, 2012 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-22412554

RESUMO

In the anion of the title salt, C(6)H(16)N(+)·C(18)H(13)O(8) (-), one of the carboxyl groups is deprotonated. Its O atoms are involved in inter-molecular hydrogen bonding with the carboxyl group of an adjacent anion and the amino group of an adjacent cation. The two benzoyloxy rings are oriented with respect to each other at a dihedral angle of 79.46 (6)°.

14.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 5): m576, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590090

RESUMO

In the title compound, [ZnCl(2)(C(20)H(18)N(4))](n), the Zn(II) ion lies on a twofold rotation axis and is four-coordinated in a tetra-hedral geometry defined by two Cl anions and two N atoms from two 4,4'-bis-[(imidazol-1-yl)meth-yl]biphenyl ligands. The mid-point of the ligand is located on an inversion center, and shows a trans conformation. The ligands link the Zn(II) ions, forming a chain structure along [10-1].

15.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 5): m589, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590099

RESUMO

In the title hetero-dinuclear complex, [CuSm(C(22)H(24)N(2)O(4))Cl(3)(CH(3)OH)(2)], the Cu(II) cation is N,N',O,O'-chelated by a 6,6'-dimeth-oxy-2,2'-[cyclo-hexane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolate ligand, and one Cl(-) anion further coordinates to the Cu(II) cation to complete the distorted square-pyramidal coordination geometry, while the Sm(III) cation is chelated by four O atoms from the same ligand, and is further coordinated by two methanol mol-ecules and two Cl(-) anions in an bicapped trigonal-prismatic geometry. Intra- and inter-molecular O-H⋯Cl hydrogen bonds are present in the structure.

16.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 5): m621, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590120

RESUMO

The asymmetric unit of the title compound, [ZnCl(2)(C(14)H(14)N(4))](n), contains a Zn(II) ion situated on a twofold rotation axis and one-half of a 1-{4-[(1H-imidazol-1-yl)meth-yl]benz-yl}-1H-imidazole (L) ligand with the benzene ring situated on an inversion center. The Zn(II) ion is coordinated by two chloride anions and two N atoms from two L ligands in a distorted tetra-hedral geometry. The L ligands bridge ZnCl(2) fragments into polymeric chains parallel to [20-1].

17.
Inorg Chem ; 50(15): 7059-65, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-21736368

RESUMO

The syntheses, structures, and magnetic properties are reported for four new lanthanide clusters [Sm(4)(µ(3)-OH)(2)L(2)(acac)(6)]·4H(2)O (1), [Gd(4)(µ(3)-OH)(2)L(2)(acac)(6)]·4CH(3)CN (2), and [Ln(4)(µ(3)-OH)(2)L(2)(acac)(6)]·2H(2)L·2CH(3)CN (3, Ln = Tb; 4, Ln = Dy) supported by salen-type (H(2)L = N,N'-bis(salicylidene)-1,2-cyclohexanediamine) and ß-diketonate (acac = acetylacetonate) ligands. The four clusters were confirmed to be essentially isomorphous by infrared spectroscopy and single-crystal X-ray diffraction. Their crystal structures reveal that the salen-type ligand provides a suitable tetradentate coordination pocket (N(2)O(2)) to encapsulate lanthanide(III) ions. Moreover, the planar Ln(4) core is bridged by two µ(3)-hydroxide, four phenoxide, and two ketonate oxygen atoms. Magnetic properties of all four compounds have been investigated using dc and ac susceptibility measurements. For 4, the static and dynamic data indicate that the Dy(4) complex exhibits slow relaxation of the magnetization below 5 K associated with single-molecule magnet behavior.

18.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 3): m367, 2011 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-21522291

RESUMO

In the title heterodinuclear salen-type complex, [CuDy(C(19)H(20)N(2)O(4))(NO(3))(3)]·CH(3)OH, the copper(II) ion is tetra-coordinated by two imino N atoms [Cu-N = 1.961 (4) and 1.968 (4) Å] and two phenolate O atoms [Cu-O = 1.931 (3) and 1.938 (3) Å] in a planar geometry. The ten-coordin-ate Dy(III) ion is ligated by six O atoms of three nitrate groups and four O atoms from the ligand [Dy-O = 2.368 (3)-2.601 (3) Å]. In the crystal, complex mol-ecules and solvent mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds.

19.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 9): m1185, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-22058837

RESUMO

In the heterodinuclear title complex, [GdZn(C(22)H(18)N(2)O(4))(CH(3)COO)(3)], the Zn(II) ion is five-coordinated in a square-pyramidal environment defined by two O atoms and two N atoms from the ligand, forming the square plane, and one acetate O atom serving as the apex, while the Gd(III) ion is nine-coordinated in an approximate mono-capped tetra-gonal-anti-prismatic environment defined by four O atoms from the ligand and five acetate O atoms.

20.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 8): m1162, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22090917

RESUMO

In the title complex, [Co(C(22)H(18)N(2)O(4))(CN)(H(2)O)]·CH(3)CN, the Co(III) ion is six-coordinated in a distorted octa-hedral environment defined by two N atoms and two O atoms from a salen ligand in the equatorial plane and one O atom from a water mol-ecule and one C atom from a cyanide group at the axial positions. O-H⋯O hydrogen bonds connect adjacent complex mol-ecules into dimers. C-H⋯N hydrogen bonds and π-π inter-actions between the benzene rings [centroid-centroid distances = 3.700 (2) and 3.845 (2) Å] are also present.

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