Bioactivity of Grape Pomace Extract and Sodium Selenite, Key Components of the OenoGrape Advanced Complex, on Target Human Cells: Intracellular ROS Scavenging and Nrf2/ARE Induction Following In Vitro Intestinal Absorption.

Oenobiol Sun Expert, a food formulation designed to enhance skin health prior to sun exposure, has been optimized by incorporating the OenoGrape Advanced Complex, which includes grape pomace extract, increased selenium content and 10% lycopene-rich tomato extract, with these constituents exhibiting high antioxidant potential. To evaluate the effects of these individual ingredients and the overall formulation at the cellular level, the AOP1 cell antioxidant efficacy assay was employed to measure the intracellular free radical scavenging activity, while the Cell Antioxidant Assay (CAA or DCFH-DA) assay was used to assess peroxidation scavenging at the plasma membrane level. The indirect antioxidant activity was examined using stably transfected cell lines containing a luciferase reporter gene controlled by the Antioxidant Response Element (ARE), which activates the endogenous antioxidant system via the Nrf2/Keap1-ARE pathway.

Synthesis and stability of the [Ti]Ti-DOTA complex: en route towards aza-macrocyclic Ti-based radiopharmaceuticals.

We report the use of DOTA as a chelator for titanium. The resulting complex is fully characterised and stability studies reveal its high kinetic inertness against transmetallation and transchelation. The radiolabeling of DOTA with Ti, a guaiacol-based liquid-liquid extraction method, leads to a high radiochemical conversion up to 98%.

Selective Hydrodeoxygenation of Lignin-Derived Phenols to Aromatics Catalyzed by NbO-Supported Iridium.

The dominating catalytic approach to aromatic hydrocarbons from renewables, deoxygenation of phenol-rich depolymerized lignin bio-oils, is hard to achieve: hydrodeoxygenation (HDO) of phenols typically leads to the loss of aromaticity and to non-negligible fractions of cyclohexanones and cyclohexanols. Here, we report a catalyst, niobia-supported iridium nanoparticles (Ir@NbO), which combines full conversion in the HDO of lignin-derived phenols with appreciable and tunable selectivity for aromatics (25-95%) under mild conditions (200-300 °C, 2.5-10 bar of H).

Unsaturated and Benzannulated -Heterocyclic Carbene Complexes of Titanium and Hafnium: Impact on Catalysts Structure and Performance in Copolymerization of Cyclohexene Oxide with CO.

Tridentate, bis-phenolate -heterocyclic carbenes (NHCs) are among the ligands giving the most selective and active group 4-based catalysts for the copolymerization of cyclohexene oxide (CHO) with CO. In particular, ligands based on imidazolidin-2-ylidene (saturated NHC) moieties have given catalysts which exclusively form polycarbonate in moderate-to-high yields even under low CO pressure and at low copolymerization temperatures. Here, to evaluate the influence of the NHC moiety on the molecular structure of the catalyst and its performance in copolymerization, we extend this chemistry by synthesizing and characterizing titanium complexes bearing tridentate bis-phenolate imidazol-2-ylidene (unsaturated NHC) and benzimidazol-2-ylidene (benzannulated NHC) ligands.

Anionic hafnium species: an active catalytic intermediate for the coupling of epoxides with CO?

A series of hafnium complexes were structurally identified showing high activity (up to 500 h) in the selective alternated copolymerization of epoxides with CO under low pressure.

Incorporation of an intact dimeric Zr oxo cluster from a molecular precursor in a new zirconium metal-organic framework.

Two zirconium-organic frameworks were synthesized by exchanging the acetate ligands in [ZrO(OH)(CHCOO)] with polydentate linkers. Partial substitution of acetate groups by a phosphine based linker yielded a new porous framework with this unique dimeric Zr cluster unit as molecular building block. More exhaustive substitution of acetate resulted in cleavage of the Zr unit and formation of UiO-67.

Coordination behavior of bis-phenolate saturated and unsaturated N-heterocyclic carbene ligands to zirconium: reactivity and activity in the copolymerization of cyclohexene oxide with CO.

Tetravalent zirconium complexes supported by tridentate bis-phenolate imidazolidin-2-ylidene (L1), imidazol-2-ylidene (L2) and benzimidazol-2-ylidene (L3) NHC ligands were synthesized and evaluated as precursors for the copolymerization of cyclohexene oxide (CHO) with CO. While the reactivity of the imidazolidinium [HL1] chloride salt with Zr(OiPr)(HOiPr), and subsequent ligand exchanges with either (CH)SiCl or LiOiPr lead to a series of heteroleptic compounds (κ-O,C,O-L1)Zr(X)(THF) (X = Cl, OiPr), both imidazolium [HL2] and benzimidazolium [HL3] chloride salts give a mixture of homoleptic (κ-O,C,O-NHC)Zr and zwitterionic (κ-O,O-HL)ZrCl(OiPr) compounds along with traces or the absence of the heteroleptic intermediate (κ-O,C,O-NHC)Zr(Cl)(OiPr)(THF). Such dissimilar reactivity between the unsaturated and saturated NHC ligands is predominantly ascribed to the increased acidity of azolium salts along with the π-donor strength of the C in L2 and L3-Zr moieties.

Sterically (un)encumbered mer-tridentate N-heterocyclic carbene complexes of titanium(iv) for the copolymerization of cyclohexene oxide with CO2.

Titanium(iv) complexes bearing an unsubstituted tridentate bis(phenolate) N-heterocyclic carbene (NHC) were synthesized and structurally identified. While sterically unencumbered NHC-Ti(iv) complexes bearing chloro and alkoxy co-ligands tend to dimerize in solution and in solid-state, the use of a bulky aryloxy as co-ligand favors the monomeric species. Upon activation by onium salts, all these complexes were found to be highly selective towards the copolymerization of cyclohexene oxide (CHO) with CO2 under mild conditions (PCO2 < 1 bar), albeit the sterically unencumbered NHC-Ti(iv) complexes are less stable and active than their structural analogues bearing bulkier substituents.

Copolymerization of cyclohexene oxide with CO2 catalyzed by tridentate N-heterocyclic carbene titanium(IV) complexes.

A new class of complexes based on titanium(IV) bearing a bisanionic mer-tridentate N-heterocyclic carbene ligand were investigated for the copolymerization of cyclohexene oxide with CO2. Upon addition of [PPN]X' salts, all complexes were found to be active and highly selective toward the formation of poly(cyclohexene oxide-alt-carbon dioxide).

Shifting from Ziegler-Natta to Philips-type catalyst? A simple and safe access to reduced titanium systems for ethylene polymerization.

Silica-supported titanium(IV) chloride is readily reduced by Mashima and co-workers' reagent (1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene) to afford materials active in ethylene polymerisation without need of aluminum alkyl cocatalyst.

A well-defined silica-supported aluminium alkyl through an unprecedented, consecutive two-step protonolysis-alkyl transfer mechanism.

Impregnation of [(AliBu(3))(Et(2)O)] on partially dehydroxylated SBA-15 affords a mesoporous material bearing the well-defined single site surface aluminium species [(≡SiO)(2)Al(iBu)(Et(2)O)].

Synthesis and characterisation of trigonal C2-chiral di- and tetra-substituted bis(oxazoline) alkyl zinc complexes and their reactivity towards protic reagents.

A series of zinc(ii) alkyl complexes stabilised by the C(2)-chiral bis(oxazoline) ligand ((R(1),R(2))BOX, with R(1) = (4S)-tBu, R(2) = H (a); R(1) = (4S)-Ph, R(2) = H (b); R(1) = (4R)-Ph, R(2) = (5S)-Ph (c)), has been synthesised and structurally characterised. ((R(1),R(2))BOX)H ligands react with ZnEt(2) in toluene to give the heteroleptic three-coordinate compounds of ((R(1),R(2))BOX)ZnEt, 1a, 1b and 1c in high yield. However, when the addition of (BOX)H ligands (a-b) over ZnEt(2) is "uncontrolled", the formation of homoleptic four-coordinate compounds are favoured (2a-b), but not for the more sterically crowded ligand (c).

Intramolecular hydroamination/cyclization of aminoalkenes catalyzed by Ln[N(SiMe(3))(2)](3) grafted onto periodic mesoporous silicas.

Homoleptic rare-earth metal silylamide complexes Ln[N(SiMe(3))(2)](3) (Ln = Y, La, Nd) were grafted onto a series of partially dehydroxylated periodic mesoporous silica (PMS) supports, SBA-15(-500) (d(p) = 7.9 nm), SBA-15LP(-500) (d(p) = 16.6 nm), and MCM-41(-500) (d(p) = 4.

Grafting of peralkylated Ln(II)Al(III) heterobimetallic complexes onto periodic mesoporous silica KIT-6.

Tetraethylaluminates of the divalent lanthanides ytterbium and samarium were grafted onto large-pore cubic periodic mesoporous silica (PMS) KIT-6, which had been dehydroxylated at 500 degrees C (specific surface area a(s): 500 m(2)g(-1); mesopore volume V(p): 1.06 cm(3)g(-1); main pore diameter: 85 A). The bimetallic materials [Ln(AlEt(4))(2)]@KIT-6(-500) were analysed by DRIFT spectroscopy, elemental analysis, nitrogen physisorption and solid-state NMR.

Selective and unexpected transformations of 2-methylpropane to 2,3-dimethylbutane and 2-methylpropene to 2,3-dimethylbutene catalyzed by an alumina-supported tungsten hydride.

2-Methylpropane and 2-methylpropene, in the presence of the W(H)(3)/Al(2)O(3) catalyst, are unexpectedly transformed to 2,3-dimethylbutane and 2,3-dimethylbutenes, respectively, with high selectivity; in case of 2-methylpropane, this reaction represents the first example of the transfer of two carbons in alkane metathesis.

Elusive trimethyllanthanum: snapshots of extensive methyl group degradation in la--Al heterobimetallic complexes.

Reactions of [La(AlMe4)3] and [Y(AlMe4)3] with PMe3 show that the phosphine can cleave Ln--CH3--Al linkages, separating Me3Al(PMe3). PMe3 (3 mol equiv) reacts with [Y(AlMe4)3] to give [(YMe3)n] contaminated with by-products containing phosphorus and aluminum. The La-based analog, [(LaMe3)n], is not formed selectively from the reaction of [La(AlMe4)3] with PMe3 or Et2O, which rather yields insoluble La/Al heterobimetallic products.

Mono-phosphacyclopentadienyl bis(tetramethylaluminate) lanthanide complexes.

Homoleptic complexes Ln(AlMe(4))(3) (Ln = La, Nd) can be straightforwardly utilized in salt metathetic exchange reactions with potassium 2,3,4,5-tetramethylphospholide (KTmp) or 3,4-dimethyl-2,5-bis(trimethylsilyl)phospholide (KDsp) affording monophosphacyclopentadienyl hydrocarbyl complexes (eta(5)-PC(4)Me(4))Ln(AlMe(4))(2) and [eta(5)-PC(4)Me(2)(SiMe(3))(2)]Ln(AlMe(4))(2) (Ln = La, Nd). The solid-state structures reveal distinct metal size effects as evidenced by X-ray diffraction analyses of monomeric neodymium Tmp and Dsp derivatives as well as the dimeric lanthanum Tmp complex. Dimerization is accomplished by intermolecular P --> La donor contacts.

Molecular understanding of alumina supported single-site catalysts by a combination of experiment and theory.

The nature and structure of grafted organometallic complexes on gamma-alumina are studied from a combination of experimental data (mass balance analysis, IR, NMR) and density functional theory calculations. The chemisorptive interactions of two complexes are analyzed and compared. The reaction of [Zr(CH2tBu)4] with alumina dehydroxylated at 500 degrees C gives {[(AlsO)2Zr(CH2tBu)]+[(tBuCH2)(Als)]-}, a bisgrafted cationic complex as major surface species.

Primary products and mechanistic considerations in alkane metathesis.

Alkane metathesis, a reaction catalyzed by the silica-supported tantalum hydride [(SiO)2Ta-H], 1, which transforms acyclic alkanes into their higher and lower homologues, was reported in 1997. New studies conducted in a continuous flow reactor in the case of propane indicate that, by varying the contact time, hydrogen and olefins are primary products. This crucial observation, as well as the known properties of tantalum alkyls to perform alpha-H or beta-H eliminations, supports the proposition of a new mechanism involving metallacyclobutane intermediates just like in olefin metathesis.