Effects of Additional Mesopores and the Surface Modification of the Y-Type Zeolite on the Alkane Oxidation Activity of Iron Complex-Encapsulated Catalysts.

Catalytic alkane hydroxylation activities of the iron complex encapsulated into the micropore of the Y-type zeolite and mesoporous zeolites, the latter of which were obtained by the partial removal of aluminum and alkaline treatment, have been explored by using HO as the oxidant. The iron complex with tris(pyridylmethyl)amine (=TPA) encapsulated into the micropore of the genuine Y-type zeolite was a more stable and effective cyclohexane hydroxylating heterogeneous catalyst compared to the corresponding copper analogue as well as the non-encapsulated homogeneous Fe-TPA complex. The chemical modification of the zeolite supports with the organic groups led to changing the catalytic activity depending on the size and the hydrophobic or hydrophilic nature of the added organic groups.

Thermosalient effect of a naphthalene diimide and tetrachlorocobaltate hybrid and changes of color and magnetic properties by ammonia vapor.

An organic-inorganic hybrid metal halide (OIMH), namely the electron-deficient naphthalene diimide (NDI) and [CoCl] hybrid (1), showed potential as a sensor for ammonia and amines, in addition to magnetic changes upon vapochromism. Crystal 1 exhibited thermosalient behavior such as leaping and movement, at around 130 °C, which could be explained to be associated with the removal of water molecules from the crystal lattice as shown by TGA and DSC. Compound 1 changed from green to black within 5 minutes when exposed to ammonia vapor, which was attributed to the radical formation in the NDI moiety as evidenced by ESR, and this phenomenon was preserved even when other mono- and di-alkylamines were applied.

Selective alkane hydroxylation and alkene epoxidation using HO and Fe(II) catalysts electrostatically attached to a fluorinated surface.

Fe(II) complexes with pentadentate ligands, including -heterocyclic carbene moieties, were prepared and electrostatically attached onto the perfluorinated surface of a mesoporous aluminosilicate. The heterogeneous catalysts were applied to the catalytic oxidation of cyclohexane and cyclohexene using HO as an oxidant in CHCN, demonstrating high performance and selectivity in alkane hydroxylation and cyclohexene epoxidation.

The Conversion of Superoxide to Hydroperoxide on Cobalt(III) Depends on the Structural and Electronic Properties of Azole-Based Chelating Ligands.

Conversion from superoxide (O) to hydroperoxide (OOH) on the metal center of oxygenases and oxidases is recognized to be a key step to generating an active species for substrate oxidation. In this study, reactivity of cobalt(III)-superoxido complexes supported by facially-capping tridentate tris(3,5-dimethyl-4-X-pyrazolyl)hydroborate ([HB(pz)]; Tp) and bidentate bis(1-methyl-imidazolyl)methylborate ([B(Im)Me(Y)]; ) ligands toward H-atom donating reagent (2-hydroxy-2-azaadamantane; AZADOL) has been explored. The oxygenation of the cobalt(II) precursors give the corresponding cobalt(III)-superoxido complexes, and the following reaction with AZADOL yield the hydroperoxido species as has been characterized by spectroscopy (UV-vis, resonance Raman, EPR).

Development of a novel scorpionate ligand with 6-methylpyridine and comparison of the structural and electronic properties of nickel(II) complexes with related tris(azolyl)borates.

A novel anionic tridentate borate ligand with a 6-methylpyridyl donor, Tpy, has been synthesized. Comparison of the molecular structures and reactivities of nickel(II)-bromido complexes with tris(azolyl)borate ligands composed of pyridyl, pyrazolyl, or oxazolinyl donors indicates the characteristic sterically demanding nature and strong electron donating ability of Tpy.

Correlation-centred variable selection of a gene expression signature to predict breast cancer metastasis.

Predictions of distant cancer metastasis based on gene signatures are studied intensively to realise precise diagnosis and treatments. Gene selection i.e.

Efficient alkane hydroxylation catalysis of nickel(ii) complexes with oxazoline donor containing tripodal tetradentate ligands.

Tris(oxazolynylmethyl)amine TOA (where R denotes the substituent groups on the fourth position of the oxazoline rings) complexes of nickel(ii) have been synthesized as catalyst precursors for alkane oxidation with meta-chloroperoxybenzoic acid (m-CPBA). The molecular structures of acetato, nitrato, meta-chlorobenzoato and chlorido complexes with TOA have been determined using X-ray crystallography. The bulkiness of the substituent groups R affects the coordination environment of the nickel(ii) centers, as has been demonstrated by comparison of the molecular structures of chlorido complexes with TOA and TOA.

Heteroleptic cobalt(iii) acetylacetonato complexes with N-heterocyclic carbine-donating scorpionate ligands: synthesis, structural characterization and catalysis.

Exposure of O2 to a reaction mixture containing bis(acac)cobalt(ii), a facially capping tris(N-heterocyclic carbene)borate ligand and 1-methylimidazole yields a heteroleptic cobalt(iii) complex with acac, 1-methylimidazole and tris(NHC)borate ligands. meta-Chloroperbenzoic acid is efficiently activated by this heteroleptic complex to catalytically oxidize cyclohexane at ambient temperature.

Tuning the O Binding Affinity of Cobalt(II) Centers by Changing the Structural and Electronic Properties of the Distal Substituents on Azole-Based Chelating Ligands.

The effects of the substituents on the chelating ligands located in the secondary coordination sphere on the O affinity of cobalt(II) centers have been explored. The combination of facially capping tridentate tris(pyrazolyl)borates (= Tp) and bidentate bis(imidazolyl)borates (= [B(Im )MeX] ; L) yields square-pyramidal cobalt(II) complexes. The structural properties of the substituent groups X attached to the boron center of L affect the arrangement of X in the resulting cobalt(II) complexes [Co(Tp)(L)].

Cobalt(II) Complexes with ,,-Scorpionates and Bidentate Ligands: Comparison of Hydrotris(3,5-dimethylpyrazol-1-yl)borate Tp* vs. Phenyltris(4,4-dimethyloxazolin-2-yl)borate To to Control the Structural Properties and Reactivities of Cobalt Centers.

Scorpionate ligands Tp* (hydrotris(3,5-dimethylpyrazol-1-yl)borate) and To (tris(4,4-dimethyloxazolin-2-yl)phenylborate) complexes of cobalt(II) with bidentate ligands were synthesized. Both Tp* and To coordinate to cobalt(II) in a tridentate fashion when the bidentate ligand is the less hindered acetylacetonate. In crystal structures, the geometry of cobalt(II) supported by the N₃O₂ donor set in the Tp* complex is a square-pyramid, whereas that in the To complex is close to a trigonal-bipyramid.

Immobilization of a Boron Center-Functionalized Scorpionate Ligand on Mesoporous Silica Supports for Heterogeneous Tp-Based Catalysts.

To develop novel immobilized metallocomplex catalysts, allyltris(3-trifluoromethylpyrazol-1-yl)borate (allyl-Tp) was synthesized. A boron-attached allyl group reacts with thiol to afford the desired mesoporous silica-immobilized Tp. Cobalt(II) is an efficient probe for estimating the structures of the immobilized metallocomplexes.

A pseudotetrahedral nickel(II) complex with a tridentate oxazoline-based scorpionate ligand: chlorido[tris(4,4-dimethyloxazolin-2-yl)phenylborato]nickel(II).

Poly(pyrazol-1-yl)borates have been utilized extensively in coordination compounds due to their high affinity toward cationic metal ions on the basis of electrostatic interactions derived from the mononegatively charged boron centre. The original poly(pyrazol-1-yl)borates, christened `scorpionates', were pioneered by the late Professor Swiatoslaw Trofimenko and have expanded to include various borate ligands with N-, P-, O-, S-, Se- and C-donors. Scorpionate ligands with boron-carbon bonds, rather than the normal boron-nitrogen bonds, have been developed and in these new types of scorpionate ligands, amines and azoles, such as pyridines, imidazoles and oxazolines, have been employed as N-donors instead of pyrazoles.

Characterization of Mononuclear Non-heme Iron(III)-Superoxo Complex with a Five-Azole Ligand Set.

Reaction of O2 with a high-spin mononuclear iron(II) complex supported by a five-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species, which was characterized by UV/Vis spectroscopy and resonance Raman spectroscopy. (1)H NMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with H-atom donating reagents to give a low-spin iron(III)-hydroperoxo species showing characteristic UV/Vis, resonance Raman, and EPR spectra.

Alkane oxidation by an immobilized nickel complex catalyst: structural and reactivity differences induced by surface-ligand density on mesoporous silica.

Immobilized nickel catalysts SBA*-L-x/Ni (L = bis(2-pyridylmethyl)(1H-1,2,3-triazol-4-ylmethyl)amine) with various ligand densities (L content (x) = 0.5, 1, 2, 4 mol % Si) have been prepared from azidopropyl-functionalized mesoporous silicas SBA-N3-x. Related homogeneous ligand L(tBu) and its Ni(II) complexes, [Ni(L(tBu))(OAc)2(H2O)] (L(tBu)/Ni) and [Ni(L(tBu))2]BF4 (2 L(tBu)/Ni), have been synthesized.

Structural characterization and oxidation reactivity of a nickel(II) acylperoxo complex.

The nickel(II)-acylperoxo complex [Ni(Tp(CF3Me))(κ(2)-mCPBA)] (1(CF3Me)) [Tp(CF3Me) = hydrotris(3-trifluoromethyl-5-methylpyrazolyl)borate, mCPBA = m-chloroperbenzoate] was isolated and fully characterized. The electrophilic oxygenation ability of 1(CF3Me) toward sulfides and olefins was confirmed. The Michaelis-Menten-type behavior of thioanisole oxygenation indicates the existence of a pre-equilibrium of substrate association in the reaction.

Manganese(II) semiquinonato and manganese(III) catecholato complexes with tridentate ligand: modeling the substrate-binding state of manganese-dependent catechol dioxygenase and reactivity with molecular oxygen.

Catecholate catwalk: Monomeric manganese(III) catecholato and manganese(II) semiquinonato complexes as the substrate-binding model of catechol dioxygenase have been synthesized and structurally characterized. The semiquinonato complex reacted with molecular oxygen to give ring-cleaved products and benzoquinone in the catalytic condition.

Characterization of nickel(II)-acylperoxo species relevant to catalytic alkane hydroxylation by nickel complex with mCPBA.

Nickel complexes with hydrotris(pyrazolyl)borate ( = Tp(R)) ligands catalyze alkane oxidation with organic peroxide meta-Cl-C(6)H(4)C([double bond, length as m-dash]O)OOH ( = mCPBA). The electronic and steric hindrance properties of Tp(R) affect the catalyses. The complex with an electron-withdrawing group containing a less-hindered ligand, that is, Tp(Me2,Br), exhibits higher alcohol selectivity.

Dioxygen activation and substrate oxygenation by a p-nitrothiophenolatonickel complex: unique effects of an acetonitrile solvent and the p-nitro group of the ligand.

The nickel(II) complex [Ni(Tp(Me2)) (SC(6)H(4)NO(2))] [1a; Tp(Me2) = hydrotris(3,5-dimethylpyrazol-1-yl)borate] reacts with O(2) to form the ligand oxygenation product ArSO(2)(-) in MeCN, and also 1a catalyzes the oxygenation of external substrates such as triphenylphosphine. The reactivity may correlate to the unique quinoid-like resonance structure of the thiophenolate ligand. The structure is stabilized by a p-nitro group and induced by coordination of MeCN.

Tuning the stability and reactivity of metal-bound alkylperoxide by remote site substitution of the ligand.

An alkylperoxonickel(II) complex with hydrotris(3,5-diisopropyl-4-bromo-1-pyrazolyl)borate, [Ni(II)(OOtBu)(Tp(iPr2,Br))] (3 a), is synthesized, and its chemical properties are compared with those of the prototype non-brominated ligand derivative [Ni(II)(OOtBu)(Tp(iPr2))] (3 b; Tp(iPr2)=hydrotris(3,5-diisopropyl-1-pyrazolyl)borate). Same synthetic procedures for the prototype 3 b and its precursors can be employed to the synthesis of the Tp(iPr2,Br) analogues. The dimeric nickel(II)-hydroxo complex, [(Ni(II)Tp(iPr2,Br))(2)(mu-OH)(2)] (2 a), can be synthesized by the base hydrolysis of the labile complexes [Ni(II)(Y)(Tp(iPr2,Br))] (Y=NO(3) (1 a), OAc (1 a')), which are obtained by the metathesis of NaTp(iPr2,Br) with the corresponding nickel(II) salts, and the following dehydrative condensation of 2 a with the stoichiometric amount of tert-butylhydroperoxide yields 3 a.

Mechanism of olfactory masking in the sensory cilia.

Olfactory masking has been used to erase the unpleasant sensation in human cultures for a long period of history. Here, we show a positive correlation between the human masking and the odorant suppression of the transduction current through the cyclic nucleotide-gated (CNG) and Ca2+-activated Cl- (Cl(Ca)) channels. Channels in the olfactory cilia were activated with the cytoplasmic photolysis of caged compounds, and their sensitiveness to odorant suppression was measured with the whole cell patch clamp.