Catalyst ligands

Electric Literature of 76089-77-5, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.76089-77-5, Name is Cerium(III) trifluoromethanesulfonate, molecular formula is C3CeF9O9S3. In a Article£¬once mentioned of 76089-77-5

Controlled hydrolysis of lanthanide complexes of the N-donor tripod tris(2-pyridylmethyl)amine versus bisligand complex formation

The reaction of the lanthanide salts LnI3(thf)4 and Ln(OTf)3 with tris(2-pyridylmethyl)amine (tpa) was studied in rigorously anhydrous conditions and in the presence of water. Under rigorously anhydrous conditions the successive formation of mono- and bis(tpa) complexes was observed on addition of 1 and 2 equiv of ligand, respectively. Addition of a third ligand equivalent did not yield additional complexes. The mono(tpa) complex [Ce(tpa)l3] (1) and the bis(tpa) complexes [Ln(tpa) 2]X3 (X = I, Ln = La(III) (2), Ln = Ce(III) (3), Ln = Nd(III) (4), Ln = Lu(III) (5); X = OTf, Ln = Eu(III) (6)) were isolated under rigorously anhydrous conditions and their solid-state and solution structures determined. In the presence of water, 1H NMR spectroscopy and ES-MS show that the successive addition of 1-3 equiv of tpa to triflate or iodide salts of the lanthanides results in the formation of mono(tpa) aqua complexes followed by formation of protonated tpa and hydroxo complexes. The solid-state structures of the complexes [Eu(tpa)(H2O)2(OTf) 3] (7), [Eu(tpa)(mu-OH)(OTf)2]2 (8), and [Ce(tpa)(mu-OH)(MeCN)(H2O]2I4 (9) have been determined. The reaction of the bis(tpa) lanthanide complexes with stoichiometric amounts of water yields a facile synthetic route to a family of discrete dimeric hydroxide-bridged lanthanide complexes prepared in a controlled manner. The suggested mechanism for this reaction involves the displacement of one tpa ligand by two water molecules to form the mono(tpa) complex, which subsequently reacts with the noncoordinated tpa to form the dimeric hydroxo species.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Related Products of 1941-30-6, A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 1941-30-6, Name is Tetrapropylammonium bromide, molecular formula is C12H28BrN. In a Article£¬once mentioned of 1941-30-6

Oxidative extraction of thiophene from n-dodecane over TS-1 in continuous process: A model for non-severe sulfur removal from liquid fuels

Liquid phase oxidation of thiophene in dodecane and subsequently extraction of the oxidized product into a polar solvent were studied in continuous process, as a model for selective removal of sulfur-containing compounds from liquid hydrocarbons under a non-severe condition. Titanium silicalite-1 (TS-1) and 30% of H2O2 were used as catalyst and oxidizing agent, respectively. The reactions were carried out at room temperature and 60 C at atmospheric pressure. TS-1 was synthesized, calcined at 550 C and characterized by XRD, ICP-AES, SEM, BET and FT-IR. The continuous stirred tank reactor (CSTR, ?150 ml) was used for the oxidative extraction in the continuous process. Thiophene (1000, 3000 ppm) in dodecane and H2O2 (1.5 %w) in methanol were fed (10-25 ml/h) by a peristaltic pump into the CSTR (150 ml) containing TS-1 (1.0 and 1.8 g). The use of TS-1 catalyst significantly improves rate of thiophene removal as the oxidized products SO4- species) can be transferred to the solvent, readily faster than the simple thiophene extraction. The reaction using methanol as a solvent showed a higher efficiency of thiophene removal, as compared to that using acetonitrile, acetic acid and water, respectively. The oxidation activity was increased when the solvent/oil ratio was increased. Increasing amounts of catalyst and decreasing feeding rate lead to an increase in oxidative extraction of thiophene. The deactivation of the catalyst is due to the titanium leaching and this can be improved when the calcinations temperature was raised.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Application of 4062-60-6, Because a catalyst decreases the height of the energy barrier, its presence increases the reaction rates of both the forward and the reverse reactions by the same amount.4062-60-6, Name is N1,N2-Di-tert-butylethane-1,2-diamine, molecular formula is C10H24N2. In a article£¬once mentioned of 4062-60-6

Photolysis of (Arylmethyl)triphenylphosphonium Salts. Substituent, Counterion, and Solvent Effects on Reaction Products

Quaternary (arylmethyl)phosphonium salts of the general formula ArCH2-PR3(+)Y(-) (Ar = substituted phenyl or 1-naphthyl; R = phenyl, ferrocenyl, or butyl; Y(-) = BF4(-) or halide) have been photolyzed in acetonitrile or in methanol.Photolysis involved the cleavage of the P-CH2 bond and the products derived from both, the arylmethyl radical and the carbocation, were formed.The proportion of the radical- and carbocation-derived products was determined as a function of substituents in group Ar, of groups R, counterions Y(-), and the solvent.For the nonoxidizable counterion (BF4(-), the proposed mechanism of the reaction involves initial homolysis, followed by the escape of the radical products from a solvent cage, or by the electron transfer from carbon to phosphorus, yielding the corresponding arylmethyl carbocation.The latter can either react with the solvent to form the observed carbocation-derived product or can undergo recombination with the tertiary phosphine formed to yield the starting phosphonium ion.Some indication of the “inverted substituent effect” resulting from the inhibition of single electron transfer from an easily oxidized radical was obtained.For the oxidizable counterions (halides), an additional pathway is suggested, that involves electron transfer from the anion, yielding the arylmethyl radical and the phosphine, thus decreasing the ionic/radical products ratio.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Application of 1271-19-8, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.1271-19-8, Name is Titanocenedichloride, molecular formula is C10Cl2Ti. In a Article£¬once mentioned of 1271-19-8

Titanium complexes of dialkanolamine ligands: Synthesis and structure

Synthesis of the title compounds, viz. [RN(CH2CH 2O)-(CHR1CR2R3O)]Ti(OiPr) 2 (13-15) and [RN(CH2CH2O)-(CHR 1CR2R3O)]2Ti (18-28), by the reaction of one or two equivalents of the corresponding dialkanolamines RN(CH2CH2OH)(CHR1CR2R3OH) (1-12) with Ti(OiPr)4 is reported. Other routes to [RN(CH 2CH2O)(CHR1CR2R3O)] 2Ti, such as the reaction of Ti(CH2Ph)4 with dialkanolamine and the reaction of TiCl4(THF)2 with dialkanolamine/Et3N were also tested. Dimeric titanocane 16, [PhCH2N(CH2CH2O)2Ti(OMe) 2]2, was obtained from the reaction of one equivalent of dialkanolamine 3 with CpTi(OMe)3. PhCH2N(CH 2CH2O)2-Ti(OMenth)2 (17) was prepared from the transalkoxylation reaction of 15 with two equivalents of menthol. The composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy as well as elemental analysis data. The possible solution structure features of 13-28 are discussed. The single-crystal X-ray diffraction study of titanocane 16 clearly indicates a dimeric structure for this compound in the solid state. According to X-ray data, compounds [PhCH2N(CH2CH2O)2] 2Ti (19), [MeN(CH2CH2O)-(CH2CHPhO)] 2Ti (20), [MeN(CH2CH2O)(CH2CPh 2O)]2Ti (23), erythro-[MeN(CH2CH 2O)(CHPhCHPhO)]2Ti (24), threo-[MeN(CH2CH 2O)(CHPhCHPhO)]2Ti (25), and {MeN(CH2CH 2O)[CH(CH2)4CHO]}2Ti (27) possess a monomeric structure with a hexacoordinate titanium atom in the solid state. Among them complexes 19, 20, 23, 25, and 27 are characterized by a cis disposition of the nitrogen atoms in the coordination environment of the Ti atom, while nitrogen atoms in 24 occupy trans positions. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Synthetic Route of 153-94-6, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.153-94-6, Name is H-D-Trp-OH, molecular formula is C11H12N2O2. In a Article£¬once mentioned of 153-94-6

Structural requirements of the competitive binding site of recombinant human indoleamine 2,3-dioxygenase

The structural requirements for substrate/inhibitor binding to the active site of recombinant human IDO are reported in this paper. Tryptophan analogues with substituents at the 5 or 6 positions were found to bind to the tryptophan binding site of IDO and serve as either substrates or inhibitors. Analogues that were more effective as substrates than inhibitors include 5-methyl-D,L-tryptophan 18, 5-methoxy-D,L-tryptophan 19, 5-hydroxy-L-tryptophan 21 and 6-methyl-D,L-tryptophan 24. Interestingly, 5-methyl-D,L-tryptophan appeared to be a better substrate than L-tryptophan. Compounds which were more active as inhibitors than substrates include 5-bromo-D,L-tryptophan 22 and 6-fluoro-D,L-tryptophan 25. 5-Fluoro-D,L-tryptophan 23 was slightly more active as a substrate. The most effective competitive inhibitor of recombinant human IDO was 6-nitro-L-tryptophan 26 which inhibited enzyme activity 52% at 1 mM concentrations (Ki = 180 muM) and was not active as a substrate. The optical isomer, 6-nitro-D-tryptophan 27 did not inhibit IDO activity indicating that binding to the active site is stereoselective. An analogue with a large substituent at the 5 position, 5-benzyloxy-D,L-tryptophan 20, was excluded from the active site. Compounds with substituents at other positions around the indole ring or the amino acid portion of tryptophan generally have low activity as substrates or inhibitors although the benzofuran analogue 5 gave moderate (43%) inhibition.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Electric Literature of 2082-84-0, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.2082-84-0, Name is N,N,N-Trimethyldecan-1-aminium bromide, molecular formula is C13H30BrN. In a Article£¬once mentioned of 2082-84-0

Functionalization of MXene nanosheets for polystyrene towards high thermal stability and flame retardant properties

Fabricating high-performance MXene-based polymer nanocomposites is a huge challenge because of the poor dispersion and interfacial interaction of MXene nanosheets in the polymer matrix. To address the issue, MXene nanosheets were successfully exfoliated and subsequently modified by long-chain cationic agents with different chain lengths, i.e., decyltrimethylammonium bromide (DTAB), octadecyltrimethylammonium bromide (OTAB), and dihexadecyldimethylammonium bromide (DDAB). With the long-chain groups on their surface, modified Ti3C2 (MXene) nanosheets were well dispersed in N,N-dimethylformamide (DMF), resulting in the formation of uniform dispersion and strong interfacial adhesion within a polystyrene (PS) matrix. The thermal stability properties of cationic modified Ti3C2/PS nanocomposites were improved considerably with the temperatures at 5% weight loss increasing by 20 C for DTAB-Ti3C2/PS, 25 C for OTAB-Ti3C2/PS and 23 C for DDAB-Ti3C2/PS, respectively. The modified MXene nanosheets also enhanced the flame-retardant properties of PS. Compared to neat PS, the peak heat release rate (PHRR) was reduced by approximately 26.4%, 21.5% and 20.8% for PS/OTAB-Ti3C2, PS/DDAB-Ti3C2 and PS/DTAB-Ti3C2, respectively. Significant reductions in CO and CO2 productions were also obtained in the cone calorimeter test and generally lower pyrolysis volatile products were recorded by PS/OTAB-Ti3C2 compared to pristine PS. These property enhancements of PS nanocomposites are attributed to the superior dispersion, catalytic and barrier effects of Ti3C2 nanosheets.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Reference of 1416881-52-1, The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.1416881-52-1, Name is 2,4,5,6-Tetra(9H-carbazol-9-yl)isophthalonitrile, molecular formula is C56H32N6. In a Article£¬once mentioned of 1416881-52-1

Assistant dopant system in solution processed phosphorescent OLEDs and its mechanism reveal

We have developed an assistant dopant system in phosphorescent OLEDs. The system is consisted of a conventional host material 4,4?-Bis(carbazol-9-yl)biphenyl (CBP), a thermally activated delayed fluorescence (TADF) 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) and a red phosphor Bis[2-(4-n-hexylphenyl)quinoline](acetylacetonate)iridium(III) (Hex-Ir(phq)2(acac)), it has achieved maximum current efficiency and external quantum efficiency of 21.52 cd/A and 9.22%, respectively. The intrinsic mechanism and energy transfer process in the system have been discussed in detail. Moreover, a satisfactory critical current density J0 of 106.1 mA/cm2 has been obtained when the assistant dopant concentration ascends to a suitable level, which indicated low efficiency roll-off of the device. By investigating the exciton generation mechanism and the transient electroluminescence (EL), the main cause of the improvement has been revealed.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

Reference of 16858-01-8, In heterogeneous catalysis, the catalyst is in a different phase from the reactants. At least one of the reactants interacts with the solid surface in a physical process called adsorption in such a way. 16858-01-8, name is Tris(2-pyridylmethyl)amine. In an article£¬Which mentioned a new discovery about 16858-01-8

Copper-catalyzed functionalized tertiary-alkylative sonogashira type couplings via copper acetylide at room temperature

There are several reports on Sonogashira couplings, but most of the reported reactions have employed aryl or alkenyl halides as coupling partners. Therefore, Sonogashira coupling is unsuitable for alkyl loadings, especially tertiary alkyl groups. In this research, we found that a copper catalyst is effective for a reaction between a terminal alkyne and an alpha-bromocarbonyl compound to form a quaternary carbon having alkynyl group at room temperature. Control experiments revealed that a copper acetylide is a key intermediate.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

In homogeneous catalysis, the catalyst is in the same phase as the reactant. The number of collisions between reactants and catalyst is at a maximum.In a patent, 20439-47-8, name is (1R,2R)-Cyclohexane-1,2-diamine, introducing its new discovery. Product Details of 20439-47-8

Highly Acidic Conjugate-Base-Stabilized Carboxylic Acids Catalyze Enantioselective oxa-Pictet?Spengler Reactions with Ketals

Acyclic ketone-derived oxocarbenium ions are involved as intermediates in numerous reactions that provide valuable products, however, they have thus far eluded efforts aimed at asymmetric catalysis. We report that a readily accessible chiral carboxylic acid catalyst exerts control over asymmetric cyclizations of acyclic ketone-derived trisubstituted oxocarbenium ions, thereby providing access to highly enantioenriched dihydropyran products containing a tetrasubstituted stereogenic center. The high acidity of the carboxylic acid catalyst, which exceeds that of the well-known chiral phosphoric acid catalyst TRIP, is largely derived from stabilization of the carboxylate conjugate base through intramolecular anion-binding to a thiourea site.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI

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Mechanism and scope of salen bifunctional catalysts in asymmetric aldehyde and alpha-ketoester alkylation

Metal complexes of C2-symmetric Lewis acid/Lewis base salen ligands provide bifunctional activation resulting in rapid rates in the enantioselective addition of diethylzinc to aldehydes (up to 92% ee). Further experiments probed the reactivity of the individual Lewis acid and Lewis base components of the catalyst and established that both moieties are essential for asymmetric catalysis. These catalysts are also effective in the asymmetric addition of diethylzinc to alpha-ketoesters. This finding is significant because alpha-ketoesters alone serve as their own ligands to accelerate racemic 1,2-carbonyl addition of Et2Zn and racemic carbonyl reduction. The latter proceeds via a metalloene pathway, and often accounts for the predominant product. Singular Lewis acid catalysts do not accelerate enantioselective 1,2-addition over these two competing paths. The bifunctional amino salen catalysts, however, rapidly provide enantioenriched 1,2-addition products in excellent yield, complete chemoselectivity, and good enantioselectivity (up to 88% ee). A library of the bifunctional amino salens was synthesized and evaluated in this reaction. The utility of the alpha-ketoester method has been demonstrated in the synthesis of an opiate antagonist.

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Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI