A Phosphorescent P/N/S Hybrid Ligand Stabilized Au2Cu Complex Selectively Senses Ammonia and Amines.

Reaction of a P/N/S hybrid ligand dpppyatc (N,N-bis((diphenylphosphaneyl)methyl)-N-(pyridin-2-yl)-amino-thiocarbamide) with Au(tht)Cl (tht = tetrahydrothiophene) and [Cu(MeCN)4]BF4 afforded cluster complex [Au2Cu(dpppyatc)2](BF4)2Cl (1). Upon excitation at 480 nm, 1 emitted orange phosphorescence at 646 nm, which was red-shifted to ~698 nm selectively in the presence of ammonia or amine vapor. This chromic photoluminescent response toward ammonia was sensitive and reversible. Complex1 could detect ammonia in aqueous solution down to concentrations of 2 ppm (w/w).

Deoxygenative Hydroboration of Aromatic Nitro Compounds Catalyzed by Tetra(diisopropylamido) Rare-Earth Metal-Lithium Bimetallic Complexes.

The first example of the reduction of a nitro compound with HBPin catalyzed by tetra(diisopropylamido) rare-earth metal-lithium bimetallic complexes LiRE(NiPr2)4(THF) (RE = La, Nd, Sm, Gd, and Y) was disclosed. A series of aromatic nitro compounds were reduced to N-borylamines in high yields (up to 99%). The derivatives of N-borylamines─amides and carbamates─were obtained in a sequential one-pot manner. Furthermore, kinetic studies of the deoxygenative hydroboration of nitro compounds were carried out.

Enantioselective Michael Addition of Malononitrile to Unsaturated Ketones Catalyzed by Rare-Earth Metal Amides RE[N(SiMe3)2]3 with Phenoxy-Functionalized TsDPEN Ligands.

The catalytic enantioselective Michael addition of α,ß-unsaturated ketones with malononitrile was well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = Y, Eu, Sm, Nd, La) with chiral phenoxy-functionalized TsDPEN ligands. The combination of lanthanum amide La[N(SiMe3)2]3 and chiral TsDPEN ligand H3L1 [H3L1 = N-((1R,2R)-2-((3,5-di-tert-butyl-2-hydroxybenzyl)amino)-1,2-diphenylethyl)-4-methylbenzenesulfonamide] in a 1:1.5 molar ratio was proved to be the optimal partner in THF, which provided the desired ß-carbonyl dinitriles in excellent yields and good to high enantioselectivities after 12 h at -15 °C.

A Multiple Stimuli-Responsive Ag/P/S Complex Showing Solvochromic and Mechanochromic Photoluminescence.

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.

Asymmetric Hydrophosphonylation of α,ß-Unsaturated Ketones Catalyzed by Rare-Earth Metal Complexes Bearing Trost Ligands.

Chiral dinuclear rare-earth metal complexes RE2Ln2 (n = 1, RE = Y(1), Eu(2), Nd(3), La(4), Gd(5); n = 2, RE = Eu(6), Gd(7)) stabilized by the corresponding Trost ligands H3L1 or H3L2 (H3L1 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol, H3L2 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-chlorophenol) were prepared and three unknown complexes 5-7 were characterized by X-ray diffraction analysis. The chiral rare-earth metal complexes 1-7 displayed high reactivity in the asymmetric hydrophosphonylation of α,ß-unsaturated ketones, and 5 mol % of complex 7 together with 10 mol % of chiral diamine (1S,2S)-1,2-cyclohexanediamine were proved to be the optimal catalyst combination. Various hydrophosphonylation products with excellent yields and high to excellent enantiomeric excess (ee) values were obtained in toluene (up to 99% yield, >99% ee).

A photoluminescent Au(I)/Ag(I)/PNN coordination complex for relatively rapid and reversible alcohol sensing.

Trinuclear complex [Au2Ag(dppmaphen)2(CN)2]PF6 photoluminesces on exposure to low molecular weight alcohols. This emission is likely due to C-Hπ 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.

Antibiofilm activities of the cinnamon extract against Vibrio parahaemolyticus and Escherichia coli.

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.

Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth Metal Complexes Containing Trost Ligands.

Four chiral dinuclear rare-earth metal complexes [REL1]2 (RE = Y(1), Eu(2), Nd(3), La (4)) stabilized by Trost proligand H3L1 (H3L1 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) were first prepared, and all were characterized by X-ray diffraction. Complex 4 was employed as the catalyst for enantioselective hydroboration reaction of substituted ketones, and the corresponding secondary alcohols with excellent yields and high ee values were obtained using reductant HBpin. The same result was also achieved using the combination of lanthanium amides La[N(SiMe3)2]3 with Trost proligand H3L1 in a 1:1 molar ratio. The experimental findings and DFT calculation revealed the possible mechanism of the enantioselective hydroboration reaction and defined the origin of the enantioselectivity in the current system.

Functional Role of p53 in the Regulation of Chemical-Induced Oxidative Stress.

The nuclear transcription factor p53, discovered in 1979, has a broad range of biological functions, primarily the regulation of apoptosis, the cell cycle, and DNA repair. In addition to these canonical functions, a growing body of evidence suggests that p53 plays an important role in regulating intracellular redox homeostasis through transcriptional and nontranscriptional mechanisms. Oxidative stress induction and p53 activation are common responses to chemical exposure and are suggested to play critical roles in chemical-induced toxicity. The activation of p53 can exert either prooxidant or antioxidant activity, depending on the context. In this review, we discuss the functional role of p53 in regulating chemical-induced oxidative stress, summarize the potential signaling pathways involved in p53's regulation of chemically mediated oxidative stress, and propose issues that should be addressed in future studies to improve understanding of the relationship between p53 and chemical-induced oxidative stress.

Reversible Solid-State Phase Transitions between Au-P Complexes Accompanied by Switchable Fluorescence.

Six complexes {(3-bdppmapy)(AuCl)2}n (1-6; 3-bdppmapy = N,N'-bis(diphenylphosphanylmethyl)-3-aminopyridine and tht = tetrahydrothiophene) were simultaneously formed by the reaction of Au(tht)Cl and 3-bdppmapy in CH2Cl2 followed by infusion with hexane. Complexes 4-6 could be produced independently by volatilizing solvent in air, solid-state heating, or solvothermal reaction. The PPh2-Au-Cl moieties extended in different directions, forming Au-Au and Au-Au-Au interactions. Complex 4 could be converted to 5 by heating to 130 °C, with the cleavage of one Au-Au bond, while 5 reverted back to 4 upon exposure to CH2Cl2 vapor over 11 h. This solid-state phase transition could be recycled and was accompanied by a change in solid-state fluorescence, without obvious intensity decay over five cycles. The reason for both the phase transition and difference in photoluminescence is related to the different numbers and strengths of aurophilic interactions in each complex that could be modeled by density functional theory calculations.

Cobalt(II) and Nickel(II) Complexes of a PNN Type Ligand as Photoenhanced Electrocatalysts for the Hydrogen Evolution Reaction.

Hydrogen will be an important energy vector of the future, and improved efficiency in electrohydrolysis will accelerate this transition. In a fundamental study, we have prepared Co(II) and Ni(II) complexes of a new PNN type ligand N-((diphenylphosphanyl)methyl)-2-amino-1,10-phenanthroline (dppmaphen) incorporating the photoactive 1,10-phenanthroline group and the strongly coordinating diphenylphosphine to obtain photoelectrochemical (PEC) catalysts [Co(dppmaphen)2(NO3)2] (1) and [Ni(dppmaphen)2Cl]Cl (2) which catalyzed the hydrogen evolution reaction (HER) in alkaline media (1 M KOH). Overpotentials (η10) of 430 (1) and 364 mV (2) could be reduced to 345 (1) and 284 mV (2) under Xe light irradiation. This irradiation generated photocurrent responses of 528 (1) and 357 uA/cm2 (2). Density function theory (DFT) calculation on the frontier orbitals of 1 and 2 were useful in understanding these differences in catalytic performance.

Visible-Light-Promoted Oxo-Sulfonylation of Ynamides with Sulfonic Acids.

A visible-light-promoted oxo-sulfonylation of ynamides with sulfonic acids is reported, giving rise to a collection of functionalized α-sulfonylated amides in a straightforward manner. The reaction proceeds sequentially through a cascade of electrophilic addition and photoinduced sulfonyl radical-sustained skeleton rearrangement. The high atom economy, mild reaction conditions, and wide substrate scope comprised the merits of this synthetic transformation.

Cycloaddition of Aziridine with CO2/CS2 Catalyzed by Amidato Divalent Lanthanide Complexes.

This is the first time that the amidato lanthanide amides ({L nLn[N(SiMe3)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(SiMe3)2]THF}{L32Eu(THF)2} (2) (HL3 = ClC6H4CONHC6H3( iPr)2)) were applied in the cycloaddition reactions of aziridines with carbon dioxide (CO2) or carbon disulfide (CS2) under mild conditions. The corresponding oxazolidinones and thiazolidine-2-thiones were obtained in good to excellent yields with good functional group tolerance.

Lanthanide complexes combined with chiral salen ligands: application in the enantioselective epoxidation reaction of α,ß-unsaturated ketones.

Readily available lanthanide amides Ln[N(SiMe3)2]3 (Ln = Nd (1), Sm (2), Eu (3), Yb (4), La (5)), combined with chiral salen ligands H2La ((S,S)-N,N'-di-(3,5-disubstituted-salicylidene)-1,2-cyclohexanediamine) and H2Lb ((S,S)-N,N'-di-(3,5-disubstituted-salicylidene)-1,2-diphenyl-1,2-ethanediamine) were employed in the enantioselective epoxidation of α,ß-unsaturated ketones. It was found that the salen-La complex shows the highest efficiency and enantioselectivity. A relatively broad scope of α,ß-unsaturated ketones was investigated, and excellent yields (up to 99%) and moderate to good enantioselectivities (37-87%) of the target molecules were achieved.

Enantioselective Reduction of Ketones Catalyzed by Rare-Earth Metals Complexed with Phenoxy Modified Chiral Prolinols.

Enantioselective reduction of ketones and α,ß-unsaturated ketones by pinacolborane (HBpin) has been well-established by using chiral rare-earth metal catalysts with phenoxy modified prolinols. A number of highly optically active alcohols were obtained from reduction of simple ketones catalyzed by ytterbium complex 1 [L4Yb(L4H)] (H2L4 = ( S)-2- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol). Moreover, α,ß-unsaturated ketones were selectively reduced to a wide range of chiral allylic alcohols with excellent yields, high enantioselectivity, and complete chemoselectivity, catalyzed by a single component chiral ytterbium complex 2 [L1Yb(L1H)] (H2L1 = ( S)-2,4-di- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol).

RE[N(SiMe3)2]3-Catalyzed Guanylation/Cyclization of Amino Acid Esters and Carbodiimides.

The example of rare-earth metal-catalyzed guanylation/cyclization of amino acid esters and carbodiimides is well-established, forming 4(3H)-2-alkylaminoquinazolinones in 65-96% yields. The rare-earth metal amides RE[N(TMS)2]3 (RE = Y, Yb, Nd, Sm, La; TMS = SiMe3) showed high activities, and La[N(TMS)2]3 performed best for a wide scope of the substrates.

An amidato divalent ytterbium cluster: synthesis and molecular structure, its reactivity to carbodiimides and application in the guanylation reaction.

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[double bond, length as m-dash]C[double bond, length as m-dash]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.

MicroRNA-3196 is inhibited by H2AX phosphorylation and attenuates lung cancer cell apoptosis by downregulating PUMA.

Histone H2AX is a tumor suppressor protein that plays an important role in apoptosis. However, the mechanism underlying the association of H2AX with apoptosis in cancer cells remains elusive. Here, we showed that H2AX knockdown in lung cancer A549 cells affected the expression of 16 microRNAs (miRNAs), resulting in the downregulation of 1 and the upregulation of 15 miRNAs. MicroRNA-3196 (miR-3196) was identified as a target of H2AX and shown to inhibit apoptosis in lung cancer cells by targeting p53 upregulated modulator of apoptosis (PUMA). Phosphorylated H2AX (γH2AX) was shown to bind to the promoter of miR-3196 and regulate its expression. In addition, H2AX phosphorylation increased H3K27 trimethylation in the promoter region of miR-3196 and inhibited the binding of RNA polymerase II to the promoter of miR-3196, leading to the inhibition of miR-3196 transcription. Taken together, these results indicated that H2AX phosphorylation regulates apoptosis in lung cancer cells via the miR-3196/PUMA pathway.

Identification of MicroRNAs Involved in Growth Arrest and Apoptosis in Hydrogen Peroxide-Treated Human Hepatocellular Carcinoma Cell Line HepG2.

Although both oxidative stress and microRNAs (miRNAs) play vital roles in physiological and pathological processes, little is known about the interactions between them. In this study, we first described the regulation of H2O2 in cell viability, proliferation, cycle, and apoptosis of human hepatocellular carcinoma cell line HepG2. Then, miRNAs expression was profiled after H2O2 treatment. The results showed that high concentration of H2O2 (600 µM) could decrease cell viability, inhibit cell proliferation, induce cell cycle arrest, and finally promote cell apoptosis. Conversely, no significant effects could be found under treatment with low concentration (30 µM). miRNAs array analysis identified 131 differentially expressed miRNAs (125 were upregulated and 6 were downregulated) and predicted 13504 putative target genes of the deregulated miRNAs. Gene ontology (GO) analysis revealed that the putative target genes were associated with H2O2-induced cell growth arrest and apoptosis. The subsequent bioinformatics analysis indicated that H2O2-response pathways, including MAPK signaling pathway, apoptosis, and pathways in cancer and cell cycle, were significantly affected. Overall, these results provided comprehensive information on the biological function of H2O2 treatment in HepG2 cells. The identification of miRNAs and their putative targets may offer new diagnostic and therapeutic strategies for liver cancer.

Synthesis and characterization of bridged bis(amidato) rare earth metal amides and their applications in C-N bond formation reactions.

Based on three bisamide proligands H2Ln (n = 1­3) (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 5­8 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.