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Five imidazolium-bridged bis(phenolato) rare-earth metal complexes 1–5 were synthesized using a readily available bisphenoxy-functionalized imidazolium salt and the corresponding rare-earth metal precursors RE[N(SiMe3)2]3 [RE = Y (1), Yb (2), Sm (3), Nd (4), La(5)], which were well characterized by single crystal diffraction analysis, elemental analysis, and NMR for complexes 1 and 5. The complexes were successfully applied to the carboxylation reactions of terminal alkynes with CO2, where complex 1 showed the highest catalytic activity. A variety of different alkynyl carboxylic acids in excellent yields were obtained under atmospheric pressure. Notably, further esterification occurred smoothly in the current catalytic system via the one-pot three-component reaction using terminal alkynes, CO2 and alkyl bromides as starting materials. Several substituted propargylic esters were obtained in moderate to excellent yields at 1 bar pressure and 50 °C. [ABSTRACT FROM AUTHOR]

A series of rare earth metal complexes (Sm (1), Eu (2), Y (3), Yb (4), and Lu (5)) based on Trost ligands were synthesized and well characterized, and catalyzed the cycloaddition of carbon dioxide and epoxides successfully. The combination of 1 mol% Sm-based complex 1 with 2 mol% tetrabutylammonium bromide (TBAB) was proved to be the optimal catalyst system for the formation of the monosubstituted cyclic carbonate at 70 °C under the atmospheric pressure. While for the more challenging disubstituted epoxides, the adduct cyclic carbonates were successfully obtained when the pressure of CO2 was elevated to 0.7 MPa. [ABSTRACT FROM AUTHOR]

The catalytic asymmetric epoxidation of α,β-unsaturated ketones by tert-butylhydroperoxide (TBHP) has been well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Y(4), Yb(5)) with chiral TADDOL ligands. It was found that the combination of Yb[N(SiMe3)2]3 and chiral TADDOL ligand H2L2 ((4S,5S)-2,2-dimethyl-α,α,α′,α′-tetra-3,5-bis(trifluormethylphenyl)-1,3-dioxolane-4,5-dimethanol) in a 1 : 1 molar ratio was the optimal choice, which provided the desired epoxides in excellent yields (89–99%) and good to high enantioselectivities (57–94% ee), using DBU as an additive. Various substrates were proved to have functional group tolerance. In addition, gram-level experiments and derivatization experiments were also studied. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus and Escherichia coli are two major foodborne pathogens. In this paper, the antibiofilm activities of the ethanol extract of cinnamon against these two bacteria were studied in detail. The antibacterial activity and the MIC of the extract were determined, and the inhibition and removing effects of the extract on the biofilms of V. parahaemolyticus and E. coli were investigated. The biofilms stained with fluorescein isothiocyanate (FITC) and concanavalin A (Con A) were also observed by confocal laser scanning microscope (CLSM). The results indicated that the extract exhibited high antibacterial activity, with the MIC against V. parahaemolyticus and E. coli was 6.25 mg/mL. The effects on V. parahaemolyticus biofilm were significant with the inhibition rate of 75.46% at MIC, and the eradication rate of 93.26% at 32MIC, respectively. As to E. coli, the inhibition rate was 48.18% at MIC, and the eradication rate was 46.16% at 8MIC. Meanwhile, the extract could notably reduce the metabolic activities and the secretion of EPS in biofilm, it inhibited 78.57% EPS formation in V. parahaemolyticus biofilm at MIC, and eliminated 61.28% EPS in mature biofilm at 4MIC. CLSM images showed that the EPS of the treated biofilm became thinner and biofilm structure was looser, when compared with the untreated control. This study elucidated that the cinnamon extract was effective to prevent biofilm formation and eradicate mature biofilms of V. parahaemolyticus and E. coli. [ABSTRACT FROM AUTHOR]

Four amidato divalent lanthanide complexes, {L nLn[N(TMS)2]THF}2 [ n = 1, Ln = Eu ( 1); n = 2, Ln = Eu ( 3), Yb ( 4); HL1 = tBuC6H4CONHC6H3( iPr)2; HL2 = C6H5CONHC6H3( iPr)2] and {L3Eu[N(TMS)2]THF}{L32Eu(THF)2} ( 2) [HL3 = ClC6H4CONHC6H3( iPr)2], were synthesized and extensively characterized. This is the first time that the amidato lanthanide amides 1- 4 were used to catalyze the reactions of CO2 and 2-aminobenzonitriles to form quinazoline-2,4(1 H,3 H)-diones at atmospheric pressure. All the complexes efficiently catalyzed the transformation, with complex 3 showing the highest activity. This catalytic system gave good to excellent yields, and good functional group tolerance. Preliminary studies were conducted to investigate the reaction mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Anionic lanthanide amidate complexes, Li(THF)Ln[C6H5C(O)NC6H3( i Pr)2]4(THF) n ·(sol) m (Ln = La (1), Nd (2), Sm (3), Yb (4), Y (5), n = 0 or 1; sol = THF or n-Hex), were synthesized for the first time by direct protonolysis reaction of LiLn(N i Pr2)4(THF) with benzamide proligand, C6H5CONHC6H3( i Pr)2 (HL). It was confirmed by their characterization data that complexes 1–5 presented rich and varied structures with changeable coordination modes of the amidate ligands. On the other hand, similar reactions of HL with neutral homoleptic lanthanide amides, Ln[N(SiMe3)2]3, cleanly yielded the neutral lanthanide amidate complexes, {PhC(O)NC6H3( i Pr)2}2Ln{OC(Ph)(C6H3( i Pr)2)N–H–N(C6H3( i Pr)2)C(Ph)O}(THF)2 (Ln = La (6), Nd (7), Sm (8)). Single-crystal X-ray structural determination revealed that complexes 6–8 featured an unprecedented N–H–N bond between two of the amidate ligands, making it the most notable difference from normal neutral analogs. Complexes 1–8 were characterized by elemental analysis and IR spectroscopy, with additional 1H NMR spectroscopy in the case of complexes 1, 5 and 6. Furthermore, both the anionic and neutral lanthanide amidate complexes proved to be efficient catalysts for the ring-opening polymerization of rac-lactide, affording heterotactic-rich polylactides. The anionic lanthanide amidate complexes exhibited significantly higher activities than their neutral counterparts due to the cooperative effect. [Copyright &y& Elsevier]

Abstract: Phosphorylation of H2AX is believed to be associated with the repair of damaged DNA. Recent findings suggest a novel function of H2AX in cellular apoptosis. Specifically, it was shown that ultraviolet A-activated JNK phosphorylates H2AX to regulate apoptosis. Here we show that serum starvation induces H2AX phosphorylation and apoptosis independent of the JNK pathway. Serum starvation induced p38 phosphorylation, whereas it did not affect the phosphorylation of ERK or JNK. Inhibition of p38 reduced H2AX phosphorylation and apoptosis. Furthermore, p38 was found to phosphorylate H2AX directly in vitro and was colocalized with H2AX in vivo. Finally, we demonstrate that H2AX phosphorylation is required for serum starvation-induced apoptosis. Taken together, these data elucidate a novel signaling pathway (p38/H2AX) to regulate apoptosis. [Copyright &y& Elsevier]

Summary: Immunofluorescence studies have revealed that H2AX is phosphorylated at the sites of DNA double-strand breaks induced by ionizing radiation and is required for recruitment of repair factors into nuclear foci after DNA damage. Therefore, the function of H2AX is believed to be associated primarily with repair of DNA damage. Here, we report a function of H2AX in cellular apoptosis. Our data showed that H2AX is phosphorylated by UVA-activated JNK. We also provided evidence showing that UVA induces caspase-3 and caspase-activated DNase (CAD) activity in both H2AX wild-type and H2AX knockout mouse embryonic fibroblasts (MEFs). However, DNA fragmentation occurred only in H2AX wild-type MEFs. Furthermore, H2AX phosphorylation was critical for DNA degradation triggered by CAD in vitro. Taken together, these data indicated that H2AX phosphorylation is required for DNA ladder formation, but not for the activation of caspase-3; and the JNK/H2AX pathway cooperates with the caspase-3/CAD pathway resulting in cellular apoptosis. [Copyright &y& Elsevier]

Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine involved in inflammation and immune responses as well as in growth factor-dependent cell proliferation, cell cycle, angiogenesis, and tumorigenesis. Several studies have documented MIF expression in the sera following hepatic resection or in the course of liver cancer progression, but there is a paucity of information regarding the effect of MIF on hepatoma cells and relating mechanisms. In this paper, by [3H] thymidine incorporation, we found that exogenously added MIF could promote the proliferation of HepG2 in a dose-dependent manner. Hepatopoietin (HPO), as a liver-specific regeneration augmenter, could be induced by the expression of MIF in hepatoma cells. The activity of HPO promoter was increased, and its levels were enhanced after MIF was overexpressed in hepatoma cells. The similarities between HPO and MIF in structure and action led us to investigate their interaction and the inducing biological significance. Using yeast two-hybrid identification, we found that HPO interacted with MIF in yeast cells, and their binding ability was higher than that between HPO and JAB1 (Jun activation domain binding protein) or MIF and JAB1 in yeast cells. Their interaction was further verified by His pull-down assay in vitro and coimmunoprecipitation experiment in vivo. They were colocalized in the cytoplasm. Both HPO and MIF could bind to JAB1 and modulate the AP-1 pathway. When HPO and MIF were cotransfected into HepG2 cells, the binding activity of MIF to JAB1 was reduced, and the activity of AP-1 was improved. In contrast, MIF overexpressed in HepG2 was unable to interfere with the binding activity of HPO to JAB1, but its potentiation on AP-1 activity was reduced significantly. Taken together, these results indicate that MIF plays an important role in the proliferation of hepatoma cells, and the effect of MIF is in concert with HPO. [Copyright &y& Elsevier]

Hepatopoietin (HPO)/augmenter of liver regeneration (ALR) is a specific hepatotrophic growth factor, which plays a key role in liver regeneration. Our previous study indicated that HPO executes its function by an inter-reactive network of the autocrine, paracrine and endocrine pathways. Recently, we have demonstrated that intracellular HPO interacts with Jun activation domain-binding protein 1 (JAB1) and leads to potentiation of activating protein-1 (AP-1) activity in a MAPK independent fashion. JAB1 is the fifth subunit of the COP9 signalosome (CSN), which is first identified as a suppressor of plant morphogenesis. A protein complex kinase activity associated with the CSN has been reported but not identified yet. In this report, we investigated further the association of HPO with the whole CSN. HPO exists in a complex with the eight-component CSN, both when purified from glycerol gradient centrifugation and when reciprocal immunoprecipitated from the lysates of transfected COS-7 cells. Intracellular HPO colocalizes with endogenous CSN in nucleus of hepatic cells. In addition, intracellular function of HPO that increases the phosphorylation of c-Jun leading to potentiate the AP-1 activity is inhibited by curcumin, a potent inhibitor of CSN-associated kinase. Taken together, these results elucidate a novel relationship of intracellular growth factor, HPO with large protein complex, CSN, which suggests a possible linkage between CSN and liver regeneration. [Copyright &y& Elsevier]

The synthesis of divalent amidato lanthanide complexes is developed and their ability to catalyze the reaction of 2-aminobenzonitriles with CO2 is investigated to give quinazoline-2,4(1H,3H)-diones. [ABSTRACT FROM AUTHOR]

The reaction of CF3COOAg, 3-bdppmapy (N,N-bis(diphenylphosphanylmethyl)-3-aminopyridine) and HTZ (1,2,4-triazole-3-thiol) in CH2Cl2/MeOH resulted in a dinuclear Ag/P/S complex [Ag2(TZ)2(3-bdppmapy)2]·xSol (1·xSol). Crystals of 1·xSol converted to 1·2MeOH in air at room temperature and further to 1 under vacuum upon heating. The solid-state, room-temperature photoluminescent emission of 1·xSol (510 nm) shifted to 494 nm (1·2MeOH) and 486 nm (1). Grinding solids of 1·2MeOH in air resulted in amorphous 1G characterized by solid-state emission at 468 nm, which converted to 1GR with 513 nm emission upon MeOH treatment. Grinding 1GR in air returned 1G, and this interconversion was reproducible over five cycles. The solid-state photoluminescence of 1G changed in response to vapors containing low–molecular weight alcohols but remained unchanged after exposure to other volatile organic compounds (VOCs) or to water vapor. Test papers impregnated with 1G could detect methanol in vapors from aqueous solutions at concentrations above 50%. Complex 1G is, therefore, an example of a stimuli-responsive molecular sensor for the detection of alcohols. [ABSTRACT FROM AUTHOR]

A facile protocol including the novel dimeric europium catalyst (I) is developed. [ABSTRACT FROM AUTHOR]

A divalent ytterbium amidate 1 ([Yb3L6]·2C7H8 for short) was synthesized via amine-elimination of Yb[N(SiMe3)2]2(TMEDA) with an amide proligand N-2,6-diisopropylphenylbenzamide HL (L = 2,6-iPr2C6H3NC(O)Ph) and structurally characterized to be a trinuclear symmetric cluster. Further studies on the reduction of iPrN=C=NiPr by complex 1 provide Yb(iii) complex 2 in hexane–THF ([(YbL2)2(μ-NiPrCNiPr)][YbL3(THF)]·C7H8), which is composed of two subunits in a unit cell, one is a bridged Yb(iii) carbene, just the same as complex 4 ([(YbL2)2(μ-NiPrCNiPr)]·3C7H8) obtained in the same reaction in toluene, and the other is a homoleptic monomeric Yb(iii) amidate (YbL3). It is also found that complex 2 decomposed to complex 3 ([YbL3]2·2C7H8) and 4 at 90 °C in toluene. Complexes 1–4 were confirmed by X-ray structure determination. Furthermore, complex 4 was proved to be a more active species than its precursor 1 in the catalytic addition of amines to carbodiimides. Finally, complex 1 was found to be an excellent pre-catalyst for the guanylation reaction with a wide scope of substrates. [ABSTRACT FROM AUTHOR]

A simple, efficient catalytic asymmetric Michael addition of malonates to unsaturated ketones has been successfully developed. This process was promoted by rare earth metal complexes 1 – 4 bearing a chiral phenoxy functionalized prolinol ligand at room temperature [L 1 RE(L 1 H) (H 2 L 1 = ( S )-2,4-di- tert -butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol, RE = Yb 1 , Y 2 , Sc 3 and L 2 Sc(L 2 H) 4 (H 2 L 2 = ( S )-2,4-di-dimethylbenzyl-6-((2-(hydroxydiphenylmethyl)-pyrrolidin-1-yl)methyl)phenol)]. Complex 3 was the best catalyst in the transformation and the products were obtained in up to 99% yield and with 90% ee. In addition, the molecular structures of the catalysts were well characterized, including X-ray determination of complex 3 . [ABSTRACT FROM AUTHOR]

Two new bis(amidate) lanthanide amides {LLn[N(SiMe3)2]·THF}2 (H2L = N,N′-(cyclohexane-1,2-diyl)-bis(4-tert-butylbenzamide); Ln = Sm(4), Yb(5)), which were prepared by the treatment of the bridged amide proligand H2L with Ln[N(SiMe3)2]3 in tetrahydrofuran, had been characterized by single-crystal X-ray diffraction and elemental analyses. Both complexes 4 and 5 and the three known isomorphs {LRE[N(SiMe3)2]·THF}2 (RE = La(1), Nd(2), Y(3)) were successfully employed in the addition of amines to carbodiimides for the first time and were found to be efficient catalysts in the transformation at 60 °C under solvent-free conditions. The Nd-based catalyst 2 showed the highest reactivity and provided various guanidines with good functional group tolerance in high to excellent yields. [ABSTRACT FROM AUTHOR]

Hepatopoietin (HPO) is a novel human hepatotrophic growth factor. Recently, we demonstrated that the extracellular ligand form of HPO can stimulate proliferation of hepatic cells via its specific receptor, which is on the surface of these cells. Also, the intracellular form of HPO potentiates the transcriptional factor AP-1. Intriguingly, a variety of HPO complexes with different molecular masses were detected in hepatocytes. In this study, we screened a human fetal liver cDNA library using the yeast two hybrid system with HPO as bait, hoping to find an HPO-binding protein. Surprisingly, HPO, itself, and a previously unidentified alternatively spliced form of HPO (named HPO23 ) were identified as interacting with HPO, indicating that HPO may exist as a homodimer or heterodimer. These results were further confirmed in vitro and in vivo . First, mass spectrometry analysis demonstrated that recombinant human HPO exist as a homodimer and that disulfide bonds were involved in the formation of rhHPO dimer. Secondly, a pull-down experiment confirmed that GST–HPO and HA–HPO, could bind together in vitro . Using HPO and various HPO deletion mutants, we identified the extreme 30 amino acids at both N- and C-termini are essential for HPO dimerization. Finally, Western blotting analysis demonstrated that HPO exists as two isoforms at 15 kDa and 23 kDa (HPO23 ) in liver cells, the 15 kDa species is located in nucleus, and the 23 kDa species mainly in the cytoplasm. These results implicated that the capacity of HPO to form both homodimers and heterodimers with the alternatively spliced forms might contribute to the existence of various HPO complexes in hepatic cells. [ABSTRACT FROM AUTHOR]

Trinuclear complex [Au2Ag(dppmaphen)2(CN)2]PF6 photoluminesces on exposure to low molecular weight alcohols. This emission is likely due to C–H⋯π interactions between the analyte and –PPh2 group, that inhibits non-radiative relaxation of the photoexcited state. Photoluminescene was quenched by removing the analyte under a stream of N2 or replacing it with H2O. This on/off switching was clearly visible, relatively rapid and recyclable. [ABSTRACT FROM AUTHOR]

Based on three bisamide proligands H2Ln (n = 1–3) (H2L1 = [(Me3C6H2CONHCH2)2CH2], H2L2 = [(Me3C6H2CONHCH2)2C(CH3)2], H2L3 = [Me3C6H2CONH(CH2)2]2NCH3), eight bis(amidato) trivalent rare-earth metal amides {LnRE[N(TMS)2]}2 (n = 1, RE = La (1), Sm (2), Nd (3), Y (4); n = 2, RE = La (5), Nd (6); n = 3, RE = La (7), Nd (8); TMS = SiMe3) were successfully synthesized by treatment of H2Ln with RE[N(TMS)2]3 in a 1 : 1 molar ratio. Complexes 3, and 5–8 were characterized by single-crystal X-ray diffraction, and NMR characterization was carried out for the La complexes 1, 5, 7 and the Y complex 4. These complexes exhibited high catalytic activities in both the direct amidation of aldehydes and the addition of amines with carbodiimine. It was found that the bis(amidato) rare earth metal amides bearing different linkers have different effects on the transformations and lanthanum and neodymium complexes performed better than others. [ABSTRACT FROM AUTHOR]

Three novel bis(amidate) rare-earth metal amides {LRE[N(SiMe3)2]·THF}2 (H2L = N,N′-(cyclohexane-1,2-diyl)bis(4-tert-butylbenzamide); RE = La(1), Nd(2), Y(3)), which were prepared by the treatment of the bridged amide proligand H2L with RE[N(SiMe3)2]3 in tetrahydrofuran, have been characterized by single-crystal X-ray diffraction, elemental analyses, and NMR for complexes 1 and 3. All the complexes were found, for the first time, to be efficient catalysts for the direct carboxylation of terminal alkynes with CO2 at ambient pressure. And the Nd-based catalyst 2 showed the highest reactivity. Various propiolic acids with a good functional group tolerance were successfully synthesized in high-to-excellent yields under mild conditions. [ABSTRACT FROM AUTHOR]

Two novel amidate rare-earth metal amides Ln[N(SiMe 3 ) 2 ]( κ 2 -L 1 ) 2 (THF) (L 1 = C 6 H 5 C(O)NC 6 H 3 ( i Pr) 2 ) (Ln = Yb ( 1 ), Y ( 2 )) were prepared through simple silylamine elimination reactions of the benzamide proligand HL 1 with Ln[N(SiMe 3 ) 2 ] 3 in tetrahydrofuran at 60 °C. These complexes were well characterized by elemental and single-crystal X-ray diffraction analyses, and the yttrium complex 2 was also characterized by NMR spectroscopic analyses. Investigation on the catalytic behaviors of amidate rare-earth metal amides, including two new complexes 1 , 2 and three known amidate divalent rare-earth metal amides {Ln[N(SiMe 3 ) 2 ]( μ -O: κ 2 -L 1 )(THF)} 2 (Ln = Yb ( 3 ), Eu ( 4 )), and Eu 2 [N(SiMe 3 ) 2 ] 2 ( μ -O: κ 2 -L 2 ) 2 (THF) 3 (L 2 = C 6 H 5 C(O)NC 6 H 3 (Me) 2 ) ( 5 ), revealed that all complexes exhibited high catalytic activities toward the hydrophosphonylation of aldehydes and some of them showed moderate to good activities toward unactivated ketones. Complex 1 showed the highest activity, which afforded a series of α-hydroxy phosphonates in good to excellent yields at room temperature after short time with low catalyst loadings. [ABSTRACT FROM AUTHOR]

Three bis(amidate) rare-earth metal amides are synthesized (containing lanthanum, neodymium and yttrium) which are found to be efficient catalysts for the direct carboxylation of terminal alkynes with CO2. [ABSTRACT FROM AUTHOR]