Dynamical intramolecular metal-to-metal ligand exchange of phosphine and thioether ligands in derivatives PtRu5(CO)16(mu6-C)

The complexes PtRu(5)(CO)(15)(PMe(2)Ph)(mu(6)-C) (2), PtRu(5)(CO)(14)(PMe(2)Ph)(2)(mu(6)-C) (3), PtRu(5)(CO)(15)(PMe(3))(mu(6)-C) (4), PtRu(5)(CO)(14)(PMe(3))(2)(mu(6)-C) (5), and PtRu(5)(CO)(15)(Me(2)S)(mu(6)-C) (6) were obtained from the reactions of PtRu(5)(CO)(16)(mu(6)-C) (1) with the appropriate ligand. As determined by NMR spectroscopy, all the new complexes exist in solution as a mixture of isomers. Compounds 2, 3, and 6 were characterized crystallographically. In all three compounds, the six metal atoms are arranged in an octahedral geometry, with a carbido carbon atom in the center. The PMe(2)Ph and Me(2)S ligands are coordinated to the Pt atom in 2 and 6, respectively. In 3, the two PMe(2)Ph ligands are coordinated to Ru atoms. In solution, all the new compounds undergo dynamical intramolecular isomerization by shifting the PMe(2)Ph or Me(2)S ligand back and forth between the Pt and Ru atoms. For compound 2, DeltaH++ = 15.1(3) kcal/mol, DeltaS++ = -7.7(9) cal/(mol.K), and DeltaG(298) = 17.4(6) kcal/mol for the transformation of the major isomer to the minor isomer; for compound 4, DeltaH++ = 14.0(1) kcal/mol, DeltaS++ = -10.7(4) cal/(mol.K), and DeltaG(298) = 17.2(2) kcal/mol for the transformation of the major isomer to the minor isomer; for compound 6, DeltaH++ = 18(1) kcal/mol, DeltaS++ = 21(5) cal/(mol.K) and DeltaG(298) = 12(2) kcal/mol. The shifts of the Me(2)S ligand in 6 are significantly more facile than the shifts for the phosphine ligand in compounds 2-5. This is attributed to a more stable ligand-bridged intermediate for the isomerizations of 6 than that for compounds 2-5. The intermediate for the isomerization of 6 involves a bridging Me(2)S ligand that can use two lone pairs of electrons for coordination to the metal atoms, whereas a tertiary phosphine ligand can use only one lone pair of electrons for bridging coordination.     

QSPR-based prediction of adsorption of halogenated aromatics on yellow-brown soil

Halogenated aromatic compounds exist widely in soil and aqueous environment. The study of their transport and distribution is quite important for pollution control and risk assessment. In the present work the adsorption coefficients of 28 halogenated benzenes, anilines and phenols on yellow-brown soil were measured with batch equilibrium method, and a prediction model was developed through the quantitative structure-property relationship (QSPR) technique. Then the obtained model was tested with Monte Carlo simulation and Jacknife methods. The results indicated that it was robust enough to estimate soil adsorption behaviors for the tested compounds. Based on the obtained model it could be deduced that the adsorption of halogenated aromatics on yellow-brown soil was not a simple partitioning process but involved complicated interactions.     

A study of thoria on the surface of gamma-Al2O3

The dispersion of thoria on the surface of gamma-Al2O3 and the surface properties of ThO2/gamma-Al2O3 samples, as well as the influence of the loading amount of thoria on the reduction behavior of copper oxide species, have been studied using XRD, XPS, FTIR, and TPR. The results indicate that the dispersion capacity of thoria, like that of ceria, is much lower than for two other tetravalent metal oxides, zirconia and titania, and the surface adsorption amount of the carbonyl compound and H2O slightly increases with increasing thoria loading. The different thoria loadings can influence the reduction behavior of the dispersed copper oxide by comparing the TPR results of CuO/ThO2/gamma-Al2O3 samples. In addition, the lower dispersion capacities of thoria and ceria on gamma-Al2O3 are tentatively discussed by considering the structural stability of the two oxides.     

Biocompatibility properties of composite scaffolds based on 1,4-butanediamine modified poly(lactide-co-glycolide) and nanobioceramics

Three-dimensional biodegradable porous scaffolds play an important role in tissue engineering. The degradable scaffold material, based on 1,4-butanediamine-modified poly(lactide-co-glycolide) (BMPLGA), nano-bioactive glass (NBAG), and nano-β-tricalciumphosphate (β-TCP), was prepared by a solution-casting/salt-leaching method. The biological properties were studied by using cell cytotoxicity, von Kossa staining, alkaline phosphatase activity, hemolytic test, acute toxicity, and genetic toxicity test. The MTT results indicated that the BMPLGA/NBAG-β-TCP materials did not show any cytotoxicity. The result of von Kossa staining showed that the introduction of the NBAG and β-TCP promoted fibroblastic differentiation and improved the mineral deposition of the BMPLGA matrix. In addition, the presence of NBAG and β-TCP in the composite further enhanced the ALP activity in comparison with the sole BMPLGA material. The hemolytic potential showed that the nanocomposite scaffolds were non-hemolytic. The BMPLGA/NBAG-β-TCP scaffolds showed no acute systemic toxicity or mutagenic action. Therefore, the results indicated the BMPLGA/NBAG-β-TCP nanocomposite scaffold could be considered as a potential bone tissue engineering implant.     

Antibacterial triterpenoids from the leaves of Ilex hainanensis Merr.

One new triterpenoid (1) and seven known analogues (2–8) were isolated from the leaves of Ilex hainanensis Merr.. Their structures were established by analysis of their MS, 1D and 2D NMR spectroscopic data and comparison with those in the literature. The antibacterial activity of compounds 1–8 were evaluated by determination of minimum inhibitory concentration using twofold microdilution broth method against Streptococcus mutans ATCC 25175 (Gram-positive) and Fusobacterium nucleatum ATCC 10953 (Gram-negative). Compounds 3 and 5 showed significant antibacterial activity against S. mutans in concentration of 9.7 μg/mL, while showed little antibacterial activity against F. nucleatum. On the contrary, the inhibitory activity of compounds 1, 2 and 6 against F. nucleatum were higher than them against S. mutans.     

Lignans from Schisandra chinensis rattan stems suppresses primary Aβ1-42-induced microglia activation via NF-κB/MAPK signaling pathway

Microglia cells play important roles in neurodegenerative diseases for clearing amyloid-β and reducing the occurrence of inflammation. In this study, the neuroinflammatory effect and the mechanism of lignans from Schisandra chinensis rattan stems (rsSCH-L) were evaluated by Aβ_1-42-induced primary microglia cell model. The results have shown that rsSCH-L could reduce the levels of pro-inflammatory cytokines, including IL-1β, TNF-α and NO. Moreover, rsSCH-L suppressed the phosphorylations of NF-κB and IκBα as well as p38, JNK and ERK proteins in Aβ_1-42-induced microglia cells. Taken together, rsSCH-L could attenuate microglia cells from neuroinflammation by activating the NF-κB/MAPK signaling pathway.     

Controllable self-assembly of parallel gold nanorod clusters by DNA origami

We demonstrate the self-assembly of three types of parallel gold nanorod clusters using a rod-like DNA origami as the template.     

Synthesis of mesoporous-silica coated multi-branched gold nanoparticles for surface enhanced Raman scattering evaluation of 4-bromomethcathinone

Mesoporous silica-coated multi-branched gold nanoparticles (bAu@mesoSiO₂) aiming for enhanced Raman sensing for 4-bromomethcathinone (4-BMC) detection is reported. In this work, we present an effective strategy to probe the Raman signal of 4-MBC. Morphologies and optical properties of the synthesized materials with different [Au³⁺]/[Au⁰] ratios are characterized utilizing transmission electron microscopy (TEM), UV–vis and mid-infrared spectroscopy. Both experimental and theoretical (simulation) studies were investigated. Taking advantages of gold core branches that provide highly localized and strongly enhanced electromagnetic fields due to plasmon resonance, surface-enhanced Raman scattering (SERS) is observed. The experimental results show that the SERS intensity exhibits a 100-fold increase with the increased average length and quantity of gold branches (nano tips). The analytical performance yielded a detection limit of 0.1?mg/ml for the 4-MBC target within 5?mins. The sensing method will likely find further improvement and broad use in the forensic science. Besides rapid detection and portability, the combination of the Raman effect and enhanced materials imparts other notable advantages, such as its non-contact and free of reagents.     

Bioinspired manganese complexes catalyzed epoxidation for the synthesis of the epoxyketone fragment of carfilzomib

We report herein an efficient catalytic epoxidation reaction for the synthesis of epoxyketone (tert-butyl ((S)-4-methyl-1-((R)-2-methyloxiran-2-yl)-1-oxopentan-2-yl)carbamate), which is an important synthetic intermediate of carfilzomib.     

菲罗啉大环双核Fe3+配合物的合成及其荧光性质

根据文献方法合成大环配体L,通过溶剂法与金属盐Fe(ClO₄)₂·6H₂O反应合成了两个新的菲罗琳大环双核Fe₃₊配合物[Fe₂(L)(μ-O)(DMF)₄]·4ClO₄(1, CCDC： 1834054）和[Fe₂(L)(μ-O)(SCN)₄]·4ClO₄(2, CCDC： 1834055）,其结构经IR和元素分析表征。晶体结构解析表明：1属三斜晶系,2属单斜晶系。配合物中两个铁原子通过一个氧桥进行连接,由于氧桥的连接使得配体发生折叠进而产生了π-π堆积。配体荧光滴定实验显示,配体L对过渡金属存在响应,随着过渡金属离子的加入,配体的荧光强度不断减弱。