Rare-earth metal complexes bearing electrophilic and nucleophilic carbon centres and their unique reactivity patterns towards pyridine derivatives.

The rare-earth metal dialkyl complexes (κ-L)RE(CHSiMe)·(THF) [RE = Lu(1a), Yb(1b), Er(1c), Y(1d), Dy(1e)] (L = 1-(2--CHNCHCH)-3-(2,6-PrCHN[double bond, length as m-dash]CH)-CHN) and the rare-earth metal monoalkyl complexes (κ-L)RE(CHSiMe)·(THF) [ = 0, RE = Lu(2a), Yb(2b); = 1, Er(2c), Y(2d), Dy(2e)], (κ-L)RE(CHSiMe)·THF [RE = Yb(3a), Er(3b), Y(3c), Dy(3d), Gd(3e)] (L = 1-(2--CHNCHCH)-3-(AdN[double bond, length as m-dash]CH)-CHN) (Ad = adamantyl, CH) have been synthesized and fully characterized. These complexes feature chelate ligands having a conjugated system (-C[double bond, length as m-dash]C-C[double bond, length as m-dash]N) with an sp carbon, which enables both electrophilic and nucleophilic carbon centres to be directly connected to the highly electrophilic rare-earth metal ions. The reactions of these complexes with different pyridine derivatives have been systematically investigated with the discovery of reactivity patterns distinct from those of previously reported transition metal complexes.

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand.

The pincer rare-earth dialkyl complexes [-RE(CHSiMe) (RE = Lu(), Yb(), Er(), Y(), Dy())] with the indol-2-yl-based NCN pincer ligand were synthesized by the reactions of the proligand ( = 1-MeNCHCH-3-(2-PrCHN═CH)CHN) with RE(CHSiMe)(THF). These complexes exhibited a variety of reactivities toward organic compounds such as amines, triphenylphosphine ylide, -phenylimidazole, pyridine derivatives, and -carborane leading to -bond metathesis, migration insertion, and redox reaction products. The reactions of the dialkyl rare-earth metal complexes with -carborane afforded the novel NCN pincer-ligated carboryne-based metallacyclopropanes which reacted with diphenyl ketone to give insertion products of the RE-C and one of the RE-C bonds, while the reaction of the carboryne-based metallacyclopropanes with diphenyldiazomethane produced the di--metallacyclopentanes via the insertions of the N═N bond of the diphenyldiazomethane into two RE-C bonds and the RE-C bond.

NIS-Promoted Chemodivergent and Diastereoselective Synthesis of Pyrrolinyl and Cyclopentenyl Spiropyrazolones via Regulated Cyclization of Alkylidene Pyrazolones with Enamino Esters.

An -iodosuccinimide-promoted annulation of alkylidene pyrazolones with enamino esters has been explored to construct a spiropyrazolone moiety through a Michael addition/iodination/intramolecular nucleophilic substitution sequence. When the reaction was performed in acetonitrile at 100 °C, it furnished pyrrolinyl spiropyrazolones exclusively in an configuration through N-attacking cyclization. When the reaction was performed in dimethyl sulfoxide at 80 °C in the presence of KHPO, it afforded cyclopentenyl spiropyrazolones exclusively in the configuration through C-attacking cyclization.

Reactivity of Rare Earth Metal Alkyl Complexes with Nitriles or Isonitrile: Versatile Ways toward Multiply Functionalized β-Diketiminato, (Iso)indolyl, and Imidazolyl Chelating Rare Earth Metal Complexes.

The reactivity of the rare earth metal alkyl complexes RE(CHSiMe)(THF) () [RE = Y (), Yb (), Lu (); = 2,5-[(2-pyrrolyl)CPh](-methylpyrrole)] with various nitriles and isonitriles has been fully developed. Treatment of the yttrium monoalkyl complex () with 2 equiv of aromatic nitriles afforded the symmetric trisubstituted β-diketiminato yttrium complexes (, , and through successive cyano group insertion into the RE-C bond and 1,3-H shift or the unsymmetric trisubstituted β-diketiminato yttrium complex () unexpectedly via a 1,3-SiMe shift when 4-(trifluoromethyl)benzonitrile was used in this reaction under the same conditions. By treating with 2 equiv of tolyl acetonitrile, an activation of the C-H bond occurred to form the corresponding β-aryl keteniminato complexes and .

Aerobic CuBr-Catalyzed Oxidative Coupling Reaction of Amidines with Exocyclic α,β-Unsaturated Cycloketones for the Synthesis of Spiroimidazolines.

A CuBr-catalyzed cascade reaction of amidines with exocyclic α,β-unsaturated cycloketones was developed, affording a large variety of spiroimidazolines in moderate to excellent yields. The reaction process involved the Michael addition and copper(II)-catalyzed aerobic oxidative coupling, in which O from air acted as the oxidant and HO was the sole byproduct.

Tomato receptor-like cytosolic kinase RIPK confers broad-spectrum disease resistance without yield penalties.

Production of reactive oxygen species (ROS) is an important immune response in plant multilayer defense mechanisms; however, direct modification of ROS homeostasis to breed plants with broad-spectrum resistance to disease has not yet been successful. In , the receptor-like cytosolic kinase AtRIPK regulates broad-spectrum ROS signaling in multiple layers of the plant immune system. Upon treatment with immune elicitors, AtRIPK is activated and phosphorylates nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, which leads to ROS production.

Indolyl-based Copper(I) Complex-Catalyzed Intermolecular Trifluoromethylazolation of Alkenes via Radical Process.

Herein, we synthesized and characterized a binuclear copper(I) complex supported by the indolyl-based ligand. Employing this complex as catalyst, we have developed a three-component intermolecular trifluoromethylazolation of alkenes to deliver various trifluoromethylated azole derivatives. The method features exclusive chemo- and regioselectivity, a broad scope of alkenes and oxazoles, thiazoles, and good tolerance of functional groups under mild conditions.

Halide-bridged tetranuclear organocopper(I) clusters supported by indolyl-based pincer ligands and their catalytic activities towards the hydrophosphination of alkenes.

Novel tetranuclear organocopper(I) clusters bridged by two halides and two indolyl-based pincer ligands were synthesized through the reactions of Cu(I) halides with lithiated ligands. Single-crystal X-ray diffraction revealed that the structure of these complexes included a [CuX] cluster unit wherein the four copper ions were stabilized by multiple Cu-Cu interactions, arranged in a distorted tetrahedral fashion and the halide anions μ-bridged with metal centers. Meanwhile, these clusters displayed excellent catalytic activities towards the hydrophosphination of alkenes under solvent-free conditions with wide functional group tolerance.

Rare-Earth-Metal-Complex-Catalyzed Hydroalkoxylation and Tandem Hydroalkoxylation/Cyclohydroamination of Isocyanates: Synthesis of Carbamates and Oxazolidinones.

Novel N,N,N-tridentate β-diketiminato rare-earth-metal dialkyl complexes RE(CHSiMe) [RE = Y (), Gd (), Yb (), Lu (); = MeC(NDipp)CHC(Me)N(CH)NCH, where Dipp = 2,6-PrCH] have been conveniently synthesized by one step from reactions of the rare-earth-metal trialkyl complexes RE(CHSiMe)(THF) (THF = tetrahydrofuran) with a pyrrolidine-functionalized β-diketiminate H, and their catalytic behaviors toward hydroalkoxylation and tandem hydroalkoxylation/cyclohydroamination of isocyanates have been described. These rare-earth-metal catalysts exhibited high efficiency in the hydroalkoxylation of isocyanates, providing a variety of -alkyl and -aryl carbamate derivatives under mild reaction conditions with a rather low catalyst loading (0.04 mol %).

Real-time monitoring of Ralstonia solanacearum infection progress in tomato and Arabidopsis using bioluminescence imaging technology.

Background: Ralstonia solanacearum, one of the most devastating bacterial plant pathogens, is the causal agent of bacterial wilt. Recently, several studies on resistance to bacterial wilt have been conducted using the Arabidopsis-R. solanacearum system.

Transformation of the sp Carbanion to Carbene with Subsequent 1,1-Migratory Insertion and Nucleophilic Substitution in Rare-Earth Metal Chemistry.

The development of Fischer-type electrophilic carbene chemistry with early transition metals has been a great challenge due to the fact that such metals in their high oxidation states lack the d electrons to stabilize the electrophilic carbene. Herein, we disclose the first experimental and theoretical findings of transformation of an sp carbanion to a Fischer-type electrophilic carbene with rare-earth metals in their high oxidation state with a d electron via electron transfer. The carbene may undergo 1,1-migratory insertion into an adjacent RE-C(sp) bond, and an unprecedented ring opening of the indole ring of the ligand occurs when the carbenes undergo nucleophilic substitution with a special organolithium reagent -MeNCHCHLi.

Three-Coordinate Pd(0) with Rare-Earth Metalloligands: Synergetic CO Activation and Double P-C Bond Cleavage-Formation Reactions.

Metalation of β-diketiminato rare-earth metal complexes LLn(PhNCHPPh) (Ln = Y, Yb, Lu) with (COD)Pd(CHSiMe) afforded three-coordinate Pd(0) complexes supported by two sterically less bulky phosphines and a Pd → Ln dative interaction. The Pd(0) center is prone to ligation with isonitrile and CO; in the latter case, the insertion of a second CO with the Y-N bond was assisted via a precoordination of CO on the Pd(0) center, which led to the formation of an anionic Pd(0) carbamoyl. The reaction of the Pd-Y complex with iodobenzene showed a remarkable double P-C bond cleavage-formation pathway within the heterobimetallic Pd-Y core to afford (PhP)PdI(Ph), imine PhNCH, and a β-diketiminato yttrium diiodide.

P-C Bond Cleavage Induced Ni(II) Complexes Bearing Rare-Earth-Metal-Based Metalloligand and Reactivities toward Isonitrile, Nitrile, and Epoxide.

Protonolysis of β-diketiminato (nacnac) rare-earth metal bis-alkyl complexes LLnR(THF) (Ln = Y and Lu) with 2 equiv of PhPNHPh or PhPCHNHPh afforded the bis-amido complexes LY(PhPNPh) and LLn(PhPCHNPh) (Ln = Y and Lu). Metalation of the latter complexes with 1 equiv of Ni(COD) led to the isolation of unusual heterobimetallic Ni(II)-Ln(III) complexes formed via P-C bond cleavage of one [PhPCHNPh] ligand. Notably, both the imine PhN═CH and phosphide PhP fragments from the P-C bond cleavage were trapped in the Ni(II)-Ln(III) core with a relatively weak interaction between the two metal centers.

Dehydrogenative Coupling of Terminal Alkynes with O/N-Based Monohydrosilanes Catalyzed by Rare-Earth Metal Complexes.

Newly synthesized rare-earth metal alkyl complexes bearing a tripyrrolyl ligand act as excellent precatalysts for the cross-dehydrogenative coupling between various terminal alkynes and O/N-based monohydrosilanes of HSi(OEt)/HSi(NMe), leading to the formation of a variety of alkoxysilylalkyne and aminosilylalkyne derivatives in good to high yields. The precatalysts RE(CHSiMe)(thf) (RE = Y(), Er(), Yb(), = 2,5-[(2-CHN)CPh](CHNMe), thf = tetrahydrofuran) were easily prepared in high yields via the reactions of RE(CHSiMe)(thf) with the proligand H in a single step. Mechanistic studies reveal that treatment of with phenylacetylene could generate the active catalytic species: dinuclear rare-earth metal alkynides ((thf)[RE(μ-C≡CPh)]) (RE = Y(), = 1; Yb(), = 0), which could react with HSi(OEt) to produce the coupling product and the dinuclear rare-earth metal hydrides ( (thf)[RE(μ-H)]) (RE = Y(); Yb()).

Facile synthesis of carboxymethyl cellulose sulfur quantum dots for live cell imaging and sensitive detection of Cr(VI) and ascorbic acid.

Nowadays the synthesis of stable fluorescent sulfur quantum dots (SQDs) remains a big challenge. Herein, the utilization of carboxymethyl cellulose (CMC) to synthesis of SQDs is reported. Benefiting from the unique composition and structure of CMC macromolecule, the resulted CMC-SQDs simultaneously show high aqueous dispersibility and stability, tunable emission, stable fluorescence and low cytotoxicity, which make them promising for working as a fluorescent probe.

Heterobimetallic Pd(0) complexes with Pd→Ln (Ln = Sc, Y, Yb, Lu) dative bonds: rare-earth metal-dominated frustrated Lewis pair-like reactivity.

A series of heterobimetallic Pd-Ln complexes with Pd→Ln (Ln = Sc, Y, Yb, Lu) dative bonds were synthesized via sequential reactions of phosphinoamine Ph2PNHAd with (Me3SiCH2)3Ln(THF)2 and (Ph3P)4Pd or (COD)Pd(CH2SiMe3)2. These complexes were characterized by NMR spectroscopy, X-ray diffractions, and computational as well as electrochemical studies, which revealed Pd→Ln dative interactions that vary according to the ionic radii of Ln3+. Furthermore, the notable dynamic structural features of the Pd-Ln complexes in solution and their unexpected frustrated Lewis pair-like reactivity toward aryl halides and ketene were also studied.

Heterobimetallic scandium-group 10 metal complexes with LM → Sc (LM = Ni, Pd, Pt) dative bonds.

Heterobimetallic scandium complexes with whole group 10 metals were synthesized. All Sc-LM complexes were characterized by NMR spectroscopy, X-ray diffraction analysis and computational studies, which revealed notable LM → Sc (LM = Ni, Pd, Pt) dative bonding interactions in these heterobimetallic systems. Versatile coordination modes toward apical donors were observed in these heterobimetallic Sc-LM complexes, among which the Sc-Ni complexes 2 and 3 were reversibly bound to N and the Sc-Pt complex 5 was coordinated to an additional PPh ligand, while in the Sc-Pd complex 4 no apical donor was ligated.

Aluminum complexes with Schiff base bridged bis(indolyl) ligands: synthesis, structure, and catalytic activity for polymerization of rac-lactide.

A series of Schiff base bridged bis(indolyl) ligands were developed for aluminum chemistry. The reactions of AlEt3 or AlMe3 with the Schiff base bridged bis(indolyl) proligands R1(-N[double bond, length as m-dash]CHC8H5NH)2 (R1 = -CH2CH2- (H2L1); -CH2CH2CH2- (H2L2); -CH2CMe2CH2- (H2L3); rac-Cy (H2L4); and R,R-Cy (H2L5)) were studied leading to the synthesis of a series of aluminum alkyl complexes L1AlEt (1)-L5AlEt (5) and L3AlMe (3b) in good yields, while the reaction of H2L3 with Al(OiPr)3 gave the aluminum alkoxide complex L3AlOiPr (3a). These aluminum complexes were characterized by spectroscopic methods and elemental analyses.

Synthesis and characterization of 2-t-butylimino-functionalized indolyl rare-earth metal amido complexes for the catalytic addition of terminal alkynes to carbodiimides: the dimeric complexes with the alkynide species in the μ-η:η bonding modes.

A series of new rare-earth metal amido complexes bearing a 2-t-butylimino-functionalized indolyl ligand were synthesized via dehydrogenation of a secondary amine, and their reactivities and catalytic performances were investigated. The reactions of 2-(BuNHCH)CHNH (1) with rare-earth metal amides [(MeSi)N]RE(μ-Cl)Li(THF) afforded the complexes [2-(BuN[double bond, length as m-dash]CH)CHN]RE[N(SiMe)] (RE = Er (2), Y (3), Dy (4), Sm (5), Nd (6)) containing the bidentate ligand via dehydrogenation of the amine to the imine group. Complexes 2-6 exhibited an excellent catalytic activity for the addition of terminal alkynes to carbodiimides affording a series of corresponding N,N'-dialkyl-propiolamidines.

A Scandium Metalloligand-Based Heterobimetallic Pd-Sc Complex: Electronic Tuning Through a Very Short Pd→Sc Dative Bond.

The first heterobimetallic Pd-Sc complex featuring a very short Pd→Sc dative bond has been synthesized and characterized by multinuclear NMR spectroscopy, X-ray diffraction analysis, and electrochemistry. Computational studies elucidated the nature of the Pd→Sc bond as a donor-acceptor interaction, which generates a more electron-deficient Pd metal center as compared to that in the mono Pd complex in their reactions with isonitrile and carbon monoxide. Cooperative reactivity has been demonstrated in the reaction with MeI.

The influence of titanium dioxide nanoparticles on their cellular response to macrophage cells.

As the most widely application of nanomaterials in biology and medicine, their interaction with biological system and the afterwards cellular responses would be addressed. Here, the agglomerate states of two kinds of TiO NPs in culture medium were characterized and the cluster specific cellular responses in RAW264.7 cells were investigated.

Synthesis, characterization, and reactivity of dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands: substituent effects on coordination and reactivity.

Two series of new dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands with different haptic modes were synthesized and characterized. The treatment of [RE(CH2SiMe3)3(THF)2] with 1 equiv. of 2-(2,6-iPr2C6H3NHC[double bond, length as m-dash]O)C8H5NH (H2L1) and 2-(2-tBuC6H4NHC[double bond, length as m-dash]O)C8H5NH (H2L2) in toluene yielded the dinuclear organo-rare-earth-metal alkyl complexes {[η1:(μ2-η1:η1)-L1]RE(CH2SiMe3)(THF)2}2 [RE = Gd (1a), Dy (1b), Y (1c), Er (1d), and Yb (1e)] and {[η1:(μ2-η1:η1):η1-L2]RE(CH2SiMe3)(THF)2}2 [RE = Gd (2a), Dy (2b), Y (2c), Er (2d), and Yb (2e)] in good yields.

Well-Defined Amidate-Functionalized N-Heterocyclic Carbene -Supported Rare-Earth Metal Complexes as Catalysts for Efficient Hydroboration of Unactivated Imines and Nitriles.

Four amidate-functionalized N-heterocyclic carbene (NHC) rare-earth metal amido complexes [(κ-N,O-κ-L)REN(SiMe)] (L = 1-(CHC═ONCHCH)-3-(CH)CH(N(CH)NC)) [RE = Er (1), Y (2), Dy (3), Gd (4)] were synthesized by one-pot reactions of 2 equiv of (1-(CHC═ONHCHCH)-3-(CH)CH-(N(CH)NCH))Br (HLBr) with 5 equiv of KN(SiMe) followed by treatment with 1 equiv of RECl in tetrahydrofuran at -40 °C. These complexes were fully characterized, and their catalytic activities toward hydroboration of unactivated imines and nitriles were investigated, and it was found that these complexes displayed excellent activities as well as remarkable functional group compatibility for imine and nitrile substrates such as halo-, alkyl-, hydroxyl-, N, N-dimethylamino-, and nitro- substituents. Among those, the chemoselectivity for this reaction among the common unsaturated functional groups was achieved in the order C═O ≫ C═N > C≡N > COEt > C═C in the current catalytic system, which may facilitate their further application in synthetic chemistry.

Di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands: synthesis, characterization and catalytic activity towards isoprene 1,4-cis polymerization.

Different di and trinuclear rare-earth metal complexes supported by 3-amido appended indolyl ligands were synthesized and their catalytic activities towards isoprene polymerization were investigated. Treatment of [RE(CHSiMe)(thf)] with 1 equiv. of 3-(CyN[double bond, length as m-dash]CH)CHNH in toluene or in THF afforded dinuclear rare-earth metal alkyl complexes having indolyl ligands in different hapticities with central metals {[η:η-μ-η-3-(CyNCH(CHSiMe))Ind]RE-(thf)(CHSiMe)} (Cy = cyclohexyl, Ind = Indolyl, RE = Yb (1), Er (2), Y (3)) or {[η-μ-η-3-(CyNCH(CHSiMe))Ind]RE-(thf)(CHSiMe)} (RE = Yb (4), Er (5), Y (6), Gd (7)), respectively.