Category: 14187-32-7

Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 14187-32-7, Name is Dibenzo-18-crown-6. In a document type is Article, introducing its new discovery., 14187-32-7

Structure of hydrated clusters of dibenzo-18-crown-6-ether in a supersonic jet – Encapsulation of water molecules in the crown cavity

The structure of dibenzo-18-crown-6-ether (DB18C6) and its hydrated clusters has been investigated in a supersonic jet. Two conformers of bare DB18C6 and six hydrated clusters (DB18C6-(H2O)n) were identified by laser-induced fluorescence, fluorescence-detected UV-UV hole-burning and IR-UV double-resonance spectroscopy. The IR-UV double resonance spectra were compared with the IR spectra obtained by quantum chemical calculations at the B3LYP/6-31+G* level. The two conformers of bare DB18C6 are assigned to “boat” and “chair I” forms, respectively, among which the boat form is dominant. All the six DB18C6-(H2O) n clusters with n = 1-4 have a boat conformation in the DB18C6 part. The water molecules form a variety of hydration networks in the boat-DB18C6 cavity. In DB18C6-(H2O)1, a water molecule forms the bidentate hydrogen bond with the O atoms adjacent to the benzene rings. In this cluster, the water molecule is preferentially hydrogen bonded from the bottom of boat-DB18C6. In the larger clusters, the hydration networks are developed on the basis of the DB18C6-(H2O)1 cluster. the Owner Societies.

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14187-32-7. Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 14187-32-7, Name is Dibenzo-18-crown-6. In a document type is Article, introducing its new discovery.

Pairwise H2/D2 Exchange and H2 Substitution at a Bimetallic Dinickel(II) Complex Featuring Two Terminal Hydrides

A compartmental ligand scaffold HL with two beta-diketiminato binding sites spanned by a pyrazolate bridge gave a series of dinuclear nickel(II) dihydride complexes M[LNi2(H)2], M = Na (Na¡¤2) and K (K¡¤2), which were isolated after reacting the precursor complex [LNi2(mu-Br)] (1) with MHBEt3 (M = Na and K). Crystallographic characterization showed the two hydride ligands to be directed into the bimetallic pocket, closely interacting with the alkali metal cation. Treatment of K¡¤2 with dibenzo(18-crown-6) led to the separated ion pair [LNi2(H)2][K(DB18C6)] (2[K(DB18C6)]). Reaction of Na¡¤2 or K¡¤2 with D2 was investigated by a suite of 1H and 2H NMR experiments, revealing an unusual pairwise H2/D2 exchange process that synchronously involves both Ni-H moieties without H/D scrambling. A mechanistic picture was provided by DFT calculations which suggested facile recombination of the two terminal hydrides within the bimetallic cleft, with a moderate enthalpic barrier of ?62 kJ/mol, to give H2 and an antiferromagnetically coupled [LNiI2]- species. This was confirmed by SQUID monitoring during H2 release from solid 2[K(DB18C6)]. Interaction with the Lewis acid cation (Na+ or K+) significantly stabilizes the dihydride core. Kinetic data for the M[L(Ni-H)2] ? H2 transition derived from 2D 1H EXSY spectra confirmed first-order dependence of H2 release on M¡¤2 concentration and a strong effect of the alkali metal cation M+. Treating [LNi2(D)2]- with phenylacetylene led to D2 and dinickel(II) complex 3- with a twice reduced styrene-1,2-diyl bridging unit in the bimetallic pocket. Complexes [LNiII2(H)2]- having two adjacent terminal hydrides thus represent a masked version of a highly reactive dinickel(I) core. Storing two reducing equivalents in adjacent metal hydrides that evolve H2 upon substrate binding is reminiscent of the proposed N2 binding step at the FeMo cofactor of nitrogenase, suggesting the use of the present bimetallic scaffold for reductive bioinspired activation of a range of inert small molecules.

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14187-32-7, Name is Dibenzo-18-crown-6, belongs to chiral-catalyst compound, is a common compound. In an article, authors is Akutagawa, Tomoyuki, once mentioned the new application about 14187-32-7.14187-32-7

Solid-state molecular rotators of anilinium and adamantylammonium in [Ni(dmit)2]- salts with diverse magnetic properties

Supramolecular rotators of hydrogen-bonding assemblies between anilinium (Ph-NH3+) or adamantylammonium (AD-NH3 +) and dibenzo[18]crown-6 (DB[18]crown-6) or meso-dicyclohexano[18] crown-6 (DCH[18]crown-6) were introduced into [Ni(dmit)2] salts (dmit2- is 2-thioxo-1,3-dithiole-4,5-dithiolate). The ammonium moieties of Ph-NH3+ and AD-NH3+ cations were interacted through N-H+?O hydrogen bonding with the six oxygen atoms of crown ethers, forming 1:1 supramolecular rotator-stator structures. X-ray crystal-structure analyses revealed a jackknife-shaped conformation of DB[18]crown-6, in which two benzene rings were twisted along the same direction, in (Ph-NH3+)(DB[18]crown-6)[Ni(dmit) 2]- (1) and (AD-NH3+)(DB[18]crown-6) [Ni(dmit)2]- (3), whereas the conformational flexibility of two dicyclohexyl rings was observed in (Ph-NH3+)(DCH[18]crown-6) [Ni(dmit)2]- (2) and (AD-NH3 +)(DCH[18]crown-6)[Ni(dmit)2]_ (4). Sufficient space for the molecular rotation of the adamantyl group was achieved in the crystals of salts 3 and 4, whereas the rotation of the phenyl group in salts 1 and 2 was rather restricted by the nearest neighboring molecules. The rotation of the adamantyl group in salts 3 and 4 was evidenced from the temperature-dependent wide-line 1H NMR spectra, dielectric properties, and X-ray crystal structure analysis, ab initio calculations showed that the potential energy barriers for the rotations of adamantyl groups in salts 3 (DeltaE ? 18 kJmol-1) and 4 (DeltaE ? 15 kJmol -1) were similar to those of ethane (?12 kJmol-1) and butane (17-25 kuJmol-1) around the C-C single bond, which were 1 order of magnitude smaller than those of phenyl groups in salts 1 (DeltaE ? 180 kJmol-1) and 2 (DeltaE ? 340 kJmol-1). 1D or 2D [Ni(dmit)2]- anion arrangements were observed in the crystals according to the shape of crown ether derivatives. The 2D weak intermolecular interactions between [Ni(dmit)2]- anions in salts 1 and 3 led to Curie-Weiss behavior with weak antiferromagnetic interaction, whereas 1D interactions through lateral sulfur-sulfur atomic contacts between [Ni(dmit)2]- anions were observed in salts 2 and 4, whose magnetic behaviors were dictated by ferromagnetic (salt 2) and singlet-triplet (salt 4) intermolecular magnetic interactions, respectively.

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Chemistry is the experimental science by definition. We want to make observations to prove hypothesis. For this purpose, we perform experiments in the lab. 14187-32-7, Name is Dibenzo-18-crown-614187-32-7, introducing its new discovery.

The photochemical substitution of benzene in [Cb*Co(C 6H6)]+ (Cb* = C4Me 4) with benzo-15-crown-5 (1) gives the corresponding pi-complex [Cb*Co(eta6-C6H4(OCH2CH 2C)CH2CH2)2O)]+ (2). A similar reaction with dibenzo-18-crown-6 (3) produces cation [Cb*Co(eta6-C6H4(OCH2CH 2OCH2CH2O)2C6H 4)]+ (4). Arene exchange is reversible, and both 1 and 3 can be regenerated by irradiation of 2 and 4 with excess benzene. The reaction of [Cb*Co(C6H6)]+ with 0.5 equiv of 3 gives dinuclear complex [trans-Cb*Co(mu-eta6, eta6-C6H4(OCH2CH 2OCH2CH2O)2C6H 4)CoCb*]2+ (5). The structures of cations 4 and 5 were confirmed by X-ray diffraction. The electrochemical behavior of complexes prepared was studied. The sodium-binding ability of cobalt complexes 2,4, and 5 (determined by NMR titration; Ka = 2500, 800, and 50, respectively) was found to be much smaller than that of the free crown ethers 1 and 3 (K a, -200 000 and 5 000 000). DFT calculations suggest that this decrease is mainly due to electrostatic repulsion of Co+ and Na + centers.

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14187-32-7, An article , which mentions 14187-32-7, molecular formula is C20H24O6. The compound – Dibenzo-18-crown-6 played an important role in people’s production and life.

The effect of crown ethers, tetraalkylammonium salts, and polyoxyethylene amphiphiles on pirarubicin incorporation in K562 resistant cells

The basic distinguishing feature of all cells expressing functional P-glycoprotein-multidrug resistance (P-gp-MDR) is a decrease in steady-state accumulation drug levels as compared to drug-sensitive controls. In an attempt to identify mechanism(s) by which MDP can be circumvented, we examined the cellular accumulation, in resistant cells, of 4′-O-tetrahydropyranyl-doxorubicin (pirarubicin) alone and in conjunction with various molecules belonging to three different classes: the crown ethers, the tetraalkylammonium salts, and the polyoxyethylene amphiphiles. The present study was performed using a spectrofluorometric method which enabled us to follow the uptake and release of fluorescent molecules by living cells while the cells were being incubated with the drug. Erythroleukemia K562 cell lines were used. Our data show that the compounds of these three completely different classes were able to increase the incorporation of pirarubicin provided they had a minimum degree of lipophilicity. Study of the growth inhibitory activity of these compounds revealed that cross-resistance to the tetraalkyl ammonium salt increased with the lipophilicity and was equal to 58 for tetraoctylammonium salt, the most lipophilic compound of this series. This demonstrates that neither the presence of a positive charge nor an aromatic moiety is required for MDR recognition.

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Chemistry is the science of change. But why do chemical reactions take place? Why do chemicals react with each other? The answer is in thermodynamics and kinetics.In a document type is Article, the author is Dubberley, Stuart R. and a compound is mentioned, 14187-32-7, Dibenzo-18-crown-6, introducing its new discovery. 14187-32-7

Group 1 and mixed Group 1 and 2 metal complexes of dianionic p-tert-butylcalix[4]arenes

Group 1 and related complexes of 1,3-O,O?-disubstituted p-tert-butylcalix[4]arene dianions [tBu-calix[4](OR) 2(O)2]2- are reported. Reaction of tBu-calix[4](OMe)2(OH)2 with NaH, K, Rb or Cs gave dimeric [M2{tBu-calix[4](OMe)2-(O) 2}]2 (M = Na 1, K 2, Rb 3 or Cs 4). The X-ray structure of 1 shows that two Na+ ions are exo-bound between the two calix[4]arene ligands while the other two are endo-bound within the calix[4]arene cavities. Reaction of tBu-calix[4](OMe) 2(OH)2 with nBuLi (2 equiv.) gave a mixture of dimeric and monomeric compounds. Complex 1 is cleaved by 15-crown-5 forming [Na2{tBu-calix[4](OMe)2(O) 2}(15-crown-5)]. The complexes 2-4 are cleaved by dibenzo-18-crown-6 forming [M2{tBu-calix[4](OMe)2(O) 2}(dibenzo-18-crown-6)]. Reactions of tBu-calix[4](OR)2-(OH)2 (R = CH2Ph or SiMe3) with Li or Na reagents gave monomeric [M2{ tBu-calix[4](OR)2(O)2}]. The reaction of 1 with CsCl gave [NaCs{tBu-calix[4](OMe)2(O) 2}]2 13 in which the two Cs+ ions are endo-bound. Reaction of 1 with CaCl2 formed [Na2Ca{ tBu-calix[4](OMe)2(O)2}2]. The Royal Society of Chemistry 2003.

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14187-32-7, An article , which mentions 14187-32-7, molecular formula is C20H24O6. The compound – Dibenzo-18-crown-6 played an important role in people’s production and life.

The Effect of Crown Ethers, Tetraalkylammonium Salts, and Polyoxyethylene Amphiphiles on Pirarubicin Incorporation in K562 Resistant Cells

The basic distinguishing feature of all cells expressing functional P-glycoprotein-multidrug resistance (P-gp-MDR) is a decrease in steady-state accumulation drug levels as compared to drug-sensitive controls. In an attempt to identify mechanism(s) by which MDR can be circumvented, we examined the cellular accumulation, in resistant cells, of 4′-O-tetrahydropyranyl-doxorubicin (pirarubicin) alone and in conjunction with various molecules belonging to three different classes: the crown ethers, the tetraalkylammonium salts, and the polyoxyethylene amphiphiles. The present study was performed using a spectrofluorometric method which enabled us to follow the uptake and release of fluorescent molecules by living cells while the cells were being incubated with the drug. Erythroleukemia K562 cell lines were used. Our data show that the compounds of these three completely different classes were able to increase the incorporation of pirarubicin provided they had a minimum degree of lipophilicity. Study of the growth inhibitory activity of these compounds revealed that cross-resistance to the tetraalkyl ammonium salt increased with the lipophilicity and was equal to 58 for tetraoctylammonium salt, the most lipophilic compound of this series. This demonstrates that neither the presence of a positive charge nor an aromatic moiety is required for MDR recognition.

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14187-32-7. Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 14187-32-7, Name is Dibenzo-18-crown-6, molecular formula is C20H24O6.

Crown ether complexation of PrCl+2 : Synthesis and structural characterisation of [PrCl2(dibenzo-18-crown-6)(H2o)][SbCl6] ¡¤ 0.5MeOH ¡¤ 0.5MeCN

Treatment of PrCl3(MeCN)3.5 with antimony(V) chloride in the presence of dibenzo-18-crown-6 provided yellow needle crystals of [PrCl2(dibenzo-18-crown-6)(H2O)] [SbCl6] ¡¤ 0.5MeOH ¡¤ 0.5MeCN following recrystallisation of the initial reaction product from boiling CH3OH/CH3CN (50 : 50). The ionic formulation was verified by X-ray crystallography. The cations have crystallographic m symmetry and the metal atoms are nine coordinate involving binding to all six crown oxygen atoms Pr – Ocrown 2.651(11)2.668(10) A, mean 2.658(10) A, two chlorine atoms 2.740(4), 2.749(4) A and a water molecule Pr – OH2O 2.487(10) A. Copyright

14187-32-7, The proportionality constant is the rate constant for the particular unimolecular reaction. the reaction rate is directly proportional to the concentration of the reactant. I hope my blog about 14187-32-7 is helpful to your research.

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14187-32-7. Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 14187-32-7, Name is Dibenzo-18-crown-6. In a document type is Article, introducing its new discovery.

Stereoselective hydrogenation of dibenzo-18-crown-6 catalyzed by carbon nanotube-supported rhodium nanoparticles

Multiwalled carbon nanotube-supported Rh nanoparticles prepared by a simple sonochemical method are highly active for catalytic hydrogenation of dibenzo-18-crown-6 to dicyclohexyl-18-crown-6. The catalytic hydrogenation reaction shows a selectivity favoring the cis-syn-cis isomer over cis-anti-cis isomer of the product by a factor of ?6. Conventional Rh catalysts supported by activated wood carbon, SiO2, or Al2O3 can only convert dibenzo-18-crown-6 to dicyclohexyl-18-crown-6 with an cis-syn-cis=cis-anti-cis ratio of <1.7. The Rh nanoparticle catalyst can be reused at least six times without losing its catalytic activity. Taylor & Francis Group, LLC. 14187-32-7, I hope this article can help some friends in scientific research. I am very proud of our efforts over the past few months and hope to 14187-32-7, help many people in the next few years.

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14187-32-7. Let¡¯s face it, organic chemistry can seem difficult to learn. Especially from a beginner¡¯s point of view. Like 14187-32-7, Name is Dibenzo-18-crown-6. In a document type is Conference Paper, introducing its new discovery.

New high-dimensional networks based on polyoxometalate and crown ether building blocks

Three novel supramolecular assemblies constructed from polyoxometalate and crown ether building blocks, [(DB18C6)Na(H2O)Na(H2O)1.5] 2Mo6O19¡¤CH3CN, 1, and [{Na(DB18C6)(H2O)2}3 (H2O)2]XMo12O40 ¡¤6DMF¡¤CH3CN (X = P, 2, and As, 3; DB18C6 = dibenzo-18-crown-6; DMF = N,N-dimethylfomamide), have been synthesized and characterized by elemental analyses, IR, UV-vis, EPR, TG, and single crystal X-ray diffraction. Compound 1 crystallizes in the tetragonal space group P4/mbm with a = 16.9701(6) A, c = 14.2676(4) A, and Z = 2. Compound 2 crystallizes in the hexagonal space group P63/m with a = 15.7435(17) A, c = 30.042(7) A, gamma = 120, and Z = 2. Compound 3 crystallizes in the hexagonal space group P63/m with a = 15,6882(5) A, c = 29.9778(18) A, gamma = 120, and Z = 2. Compound 1 exhibits an unusual three-dimensional network with one-dimensional sandglasslike channels based on the extensive weak forces between the oxygen atoms on the [MO6O19]2- polyoxoanions and the CH2 groups of crown ether molecules. Compounds 2 and 3 are isostructural, and both contain a novel semiopen cagelike trimeric cation [{Na(DB18C6)(H2O)2}3 (H2O)2]3+. In their packing arrangement, an interesting 2-D “honeycomblike” “host” network is formed, in which the [XMo12O40]3- (X = As and P) polyoxoanion “guests” resided.

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