Category: 14187-32-7

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. 14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, name: Dibenzo-18-crown-6

Supramolecular self-assembly for designing non-centrosymmetric crystals based on Keggin polyoxometallates and crown ether

We report the synthesis of five novel crystals [(4-BrAni+)(DB[18]crown-6)]2[SMo12O402-]¡¤2CH3CN (1), [(4-BrAni+)(B[18]crown-6)]2[SMo12O402-]¡¤CH3CN (2), [(4-BrAni+)(B[18]crown-6)]3[PMo12O402-]¡¤2CH3CN (3), [(3-AP+)3(B[18]crown-6)2][PMo12O403-] (4) and [NBu4+][(3-AP2+)(DB[30]crown-10)][PMo12O403-]¡¤CH3CN (5) (4-BrAni+ = 4-bromoanilinium; B[18]crown-6 = benzo[18]-crown-6; DB[18]crown-6 = dibenzo[18]-crown-6; DB[30]crown-10 = dibenzo[30]-crown-10; 3-AP+ = 3-aminopyridinium; 3-AP2+ = 3-ammoniumpyridinium; NBu4+ = tetrabutylammonium). In order to construct non-centrosymmetric crystals, the five crystals were designed using a method to gradually introduce asymmetry into the building units. Crystal 1 was constructed with a symmetric supramolecular cation (SPC) [(4-BrAni+)(DB[18]crown-6)], resulting in a P21/n space group. The asymmetric SPC [(4-BrAni+)(B[18]crown-6)] was introduced into [SMo12O402-] to obtain crystal 2, which belongs to the symmetric P1 space group. Introducing trivalent [PMo12O403-], [(4-BrAni+)(B[18]crown-6)] produced crystal 3 with a non-centrosymmetric Pc space group. The asymmetric sandwich SPC [(3-AP+)3(B[18]crown-6)2] was designed with multiple hydrogen bonding sites on the 3-AP+ cation, and crystal 4 was obtained with trivalent [PMo12O403-]. Crystal 4 has the properties of the chiral P1 space group. The distorted SPC (3-AP2+)(DB[30]crown-10) was constructed using flexible DB[30]crown-10, resulting in crystal 5 which matched the chiral P21 space group with trivalent [PMo12O403-]. This work focuses on strategies for the rational design of novel non-centrosymmetric crystals without a chiral synthon.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, Formula: C20H24O6

Spectroscopic properties of uranyl crown ether complexes in non-aqueous solvents

The spectroscopic properties of the complexes of uranyl with oxacrowns, azacrowns, thiacrowns of different ring size, polyethyleneglycols (PEG-200, PEG-300, PEG-400), and [2.2.1] and [2.2.2] cryptands were studied in acetonitrile and propylene carbonate solutions by absorption and luminescence spectroscopy. Depending on the ligand, marked differences in the fine structure of the spectra were observed. The crown ethers with six oxygen atoms (18-crown-6, dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 and [2,4]-dibenzo-18-crown-6) form inclusion complexes with the uranyl ion in the central cavity. In the case of 18-crown-6 and dibenzo-18-crown-6, a complex with a high coordination symmetry is formed. Outer-sphere complexes are formed with the crown ethers with small ring size (12-crown-4 and 15-crown-5) and with PEG-200. Only minor changes in the spectra were observed when changing the ligand. The spectra of the large crown ethers ([3,4]-dibenzo-21-crown-7, dibenzo-24-crown-8 and dibenzo-30-crown-10), together with those of PEG-300 and PEG-400 show that these ligands coordinate in the equatorial plane to the uranyl ion. In the presence of competing inorganic ligands like chloride and nitrate ions, the crown ether is replaced in the first coordination sphere. Azacrowns and cryptands coordinate externally to the uranyl ion, and the corresponding spectra do not show fine structure. In the case of the thiacrowns, no coordination of the ligand to the uranyl ion was observed.

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14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6, belongs to chiral-catalyst compound, is a common compound. In a patnet, once mentioned the new application about 14187-32-7, Safety of Dibenzo-18-crown-6

A tricarboxylated PtCl(terpyridine) derivative exhibiting pH-dependent photocatalytic activity for H2 evolution from water

The first negatively charged PtCl(tpy) (tpy = 2,2?:6?,2??-terpyridine) derivative, formulated as Na2[PtCl(tctpy)]¡¤5H2O (tctpy = 2,2?:6?,2??-terpyridine-4,4?,4??-tricarboxylate), was prepared, characterized, and investigated in detail for its activity as a single-component photocatalyst that drives water reduction to H2 in the presence of a sacrificial electron donor (EDTA). This compound was confirmed to exist in its fully deprotonated form [PtCl(tctpy)]2- in aqueous media at pH > 4.4. Despite its dianionic character, [PtCl(tctpy)]2- was found to form a specific adduct with anionic EDTA (i.e., YH22- and YH3-, where YH4 is a fully protonated form of EDTA), enabling reductive quenching of the triplet metal-to-ligand charge transfer excited state within the adduct, leading to subsequent electron transfer steps correlated with Pt(ii)-catalyzed H2 evolution from water. Electrochemical studies also reveal that the compound exhibits a unique pH-dependent first reduction (i.e., tctpy-centered reduction), leading to our realization of the first example of a Pt(ii)-based molecular system that photocatalyzes the H2 evolution reaction accompanied by a ligand-based proton-coupled electron transfer (PCET) process.

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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. 14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, Safety of Dibenzo-18-crown-6

Investigations of the poly iodides H3O¡¤Ix (x = 3, 5 or 7) as dibenzo-18-crown-6 complexes

The compounds [H3O(dibenzo-18-crown-6)][Ix(x = 3,5,7) have been synthesised and investigated by X-ray diffraction as well as Raman and far-IR spectroscopy. The structure of the triiodide contains two independent, slightly asymmetric and bent I3- ions with I-I distances in the range 2.92-2.94 A. The pentaiodide can be described as composed of (I3-)¡¤I2, where the I-I distances in the asymmetric and slightly bent I3 unit are 2.894(2) and 2.942(2) A and in the I2 unit 2.763(2) A. The L-shaped I5- ions are linked together forming a chain of I10 rectangles through van der Waals interactions in the range 3.7-3.8 A. The structure determination supports a pyramidal geometry of the H3O+ ion in the dibenzo-18-crown-6 moiety of both structures. Because of severe crystal twinning the crystal structure of the heptaiodide could not be determined. However, the results from the spectroscopic investigation are consistent with a heptaiodide of composition (I3-)¡¤2I2. The Royal Society of Chemistry 2000.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, name: Dibenzo-18-crown-6

Relationship between the Extractability and the Rate of Transfer of Potassium Ion by Macrocyclic Carriers in Liquid Membrane Systems

The relationship between the extractability and the rate of transfer of potassium ion by macrocyclic carriers was investigated in chloroform membrane systems.The rates of ion uptake, ion release, and ion transport and the liquid-liquid extraction constants were determined for a series of carriers (polynactin, dibenzo-18-crown-6, dicyclohexano-18-crown-6, and 18-crown-6).Kinetic equations for ion uptake and release are developed, and the apparent rate constants were calculated by introducing the experimentally determined extraction constants.The rate constants for the ion release and ion uptake are comparable to each other.For the four macrocyclic carriers employed, the rate of uptake was found to control the overall rate of transport through the liquid membrane.Both the rate of uptake and that of transport depend crucially on the extractability of the metal ion.A systematic analysis of each rate taking the constituent equilibria into account indicates that a macrocyclic ligand which forms a more stable complex with the metal ion and is less hydrophobic is preferable as a mobile carrier in liquid membrane systems.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Conference Paper£¬once mentioned of 14187-32-7, Application In Synthesis of Dibenzo-18-crown-6

Reaction of cytisine with 4?-substituted dibenzo-18-crown-6 sulfonylchlorides

Sulfamides were synthesized via the reaction of cytisine with 4?,4?(5?)-dibenzo-18-crown-6-disulfonyl-, 4? -secbutyl-4?(5?)-dibenzo-18-crown-6-sulfonyl-, and 4?-acetyl-4?(5?)-dibenzo-18-crown-6-sulfonylchlorides. The structures of the prepared compounds were confirmed by PMR.

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Crown ether ligation: An approach to low-oxidation-state indium compounds

(Chemical Equation Presented) A crowning achievement: Appropriately sized crown ethers can stabilize or enable In1 compounds to be generated without decomposition or disproportionation (see scheme). The resulting coordination compounds include the only example of a donor group complexed to a monomeric, univalent Group 13 center and the first example of a homoleptic Group 13-Group 13 donor-acceptor complex.

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The reaction rate of a catalyzed reaction is faster than the reaction rate of the uncatalyzed reaction at the same temperature.14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6. In a Article£¬once mentioned of 14187-32-7, HPLC of Formula: C20H24O6

[Experimental evaluation of the toxicity and late effects of crown ethers at acceptable levels in water]

[Experimental evaluation of the toxicity and late effects of crown ethers at acceptable levels in water]

The reactant in an enzyme-catalyzed reaction is called a substrate. Enzyme inhibitors cause a decrease in the reaction rate of an enzyme-catalyzed reaction.I hope my blog about 14187-32-7 is helpful to your research., HPLC of Formula: C20H24O6

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Selective Carriers of Ammonium Ions. 1. Synthesis and Template Effects of CsCl and X-ray Structure and Ionophoric Properties of Polyether Crowns Containing 1-Methyl-3,5-bis(methylene)-1H-pyrazole Units

A new series of asymmetric crown ethers of cyclic (7, 8) and acyclic structure (9) containing 1-methyl-3,5-bis(methylene)-1H-pyrazole units have been synthesized.Crowns 7 and 8 having 18 and 36 ring atoms have been obtained in 24percent and 25percent yields respectively by 1:1 and 2:2 cyclization of 1-methyl-3,5-bis(chloromethyl)-1H-pyrazole and disodium tetraethylene glycolate under the template effect of CsCl.When the Cs+ caution was not present in the above reaction, the crowns 7 and 8 were formed in lower yields.The X-ray structure of smaller crown 7 showed a flexible irregular cavity which presents an internal overall twist that changes the pseudo-2-fold axis of symmetry in the neighborhood of pyrazole ring into a pseudo mirror plane for the rest of it.A 1H and 13C NMR study has shown that in the Eu(fod)3-crown 7 complex, the pyrazolic sp2 nitrogen and the oxygens belonging to the polyether cavity are cooperatively acting as donor sites, the Eu+ being near the pyrazole side least hindered by the methyl group.The transport rates of alkali and ammonium ions are much higher for all polyether ligands 7-9 then for ester crowns 3 and 4 evaluated before.The larger crown, 8, is a selective carrier of NH4+ in relation to K+ and Na+ ions.However, the smaller crown, 7, and its acyclic analogue 9 (which shows a “plateau” selectivity toward NH4+ and alkali ions) are better carriers of K+ ions.

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Isosteviol and some of its derivatives as receptors and carriers of amino acid picrates

The ability of diterpenoid isosteviol 1 (ent-16-oxobeyeran-19-oic acid) and some of its derivatives with ester and amide groups to bind amino acid picrates in the course of their transport through a liquid chloroform membrane was observed for the first time. Isosteviol was very competitive with dibenzo-18-crown-6 and N,N?-bis(isostevioyl)-1,4-phenylenediamine 5 was even more effective in transportation of d,l-tryptophan through a liquid chloroform membrane.

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