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824-78-2Relevant articles and documents
Two picolinamide-based Zn(II) coordination polymers: Syntheses, structures, and catalytic activities
Li, Linke,Yao, Hongchang,Zhao, Jingjing,Yang, Zhihui,Hou, Hongwei
, p. 46 - 52 (2012)
Two picolinamide-based zinc(II) coordination polymers {[Zn(SO 4)(3-bpit) (CH3OH)2]·2CH 3OH}n (1)(3-bpit = N,N'-bis(3-pyridylformyl)imidazolidine- 2-thione) and [Zn(SCN)2(4-bpit)]n(2) (4-bpit = N,N'-bis(4-pyridylformyl)imidazolidine -2-thione) have been synthesized and structurally characterized. In complexes 1 and 2, the picolinamide-based ligands, 3-bpit and 4-bpit, function as bridging bidentate mode, leading to polymeric structures. Complex 1 is a two-dimensional coordination polymer while 2 exhibits a one-dimensional chain structure. The hydrolysis of 4-nitrophenyl acetate catalyzed by complexes 1 and 2 under mild conditions was also investigated.
One-step green synthesis of composition-tunable Pt-Cu alloy nanowire networks with high catalytic activity for 4-nitrophenol reduction
Zhang, Yingfang,Xia, Yan,Yan, Saisai,Han, Jia,Chen, Yifan,Zhai, Wenzhong,Gao, Zhinong
, p. 17461 - 17468 (2018)
Controlling the structure, morphology, and composition of noble metals is of great significance to improve the catalytic activity and stability of catalysts. Herein, we have successfully synthesized self-interconnecting Pt-Cu alloy nanowire networks (NWNs) with controllable compositions via the co-reduction of the metal precursors potassium chloroplatinate (K2PtCl6) and CuCl2 with sodium borohydride (NaBH4). Owing to the hydrogen bubbles formed by NaBH4 hydrolysis and oxidation as a dynamic template, the facile strategy was carried out without any organic solvent, capping agent, polymer, or special experimental device, ensuring that the surfaces of NWNs were definitely “clean”. The performance of the as-prepared Pt-Cu alloy NWNs for the reduction of 4-NP was dramatically improved compared with that of pure Pt NWNs and the commercial Pt/C catalyst. Particularly, the PtCu NWNs with a Pt/Cu atomic ratio of 1?:?1 exhibited excellent catalytic activity and reusability for the reduction of toxic 4-NP. The reaction rate constant and activity factor of the PtCu NWNs reached 1.339 × 10?2 s?1 and 66.95 s?1 g?1, respectively, which were dramatically better than those of pure Pt NWNs (11.5-fold) and commercial Pt/C (13-fold). The superior catalytic activity and reusability can mainly be attributed to the clean surface, the synergistic effect of Cu and Pt atoms and the self-interconnecting nanowire network structure.
In situ generation of a high-performance Pd-polypyrrole composite with multi-functional catalytic properties
Choudhary, Meenakshi,Islam, Rafique Ul,Witcomb, Michael J.,Mallick, Kaushik
, p. 6396 - 6405 (2014)
We report on a bottom up approach for the synthesis of a Pd-polypyrrole nanocomposite material. The composite material was characterized by means of different techniques, such as UV-vis, IR, and Raman spectroscopy, which offered information about the chemical structure of the polymer, whereas electron microscopy images provided information regarding the morphology of the composite material and the distribution of the metal particles in the polymer matrix. During the synthesis of the nanocomposite, the Pd nanoparticles act as a catalyst for a model proton-coupled electron transfer reaction. The Pd-polypyrrole nanocomposite material was also used as a catalyst for the electro-catalytic detection of tryptophan, a precursor for some neurotransmitters. This journal is the Partner Organisations 2014.
Creation and stabilisation of tuneable open metal sites in thiocyanato-bridged heterometallic coordination polymers to be used as heterogeneous catalysts
Tabe, Hiroyasu,Matsushima, Masaaki,Tanaka, Rika,Yamada, Yusuke
, p. 17063 - 17069 (2019)
A series of thiocyanato-bridged heterometallic coordination polymers with a 3D reticular network have been synthesised by the reaction of [PtIV(SCN)6]2- with MII ions to form {MII[PtIV(SCN)6]}n and {[MII(CH3OH)2][PtIV(SCN)6]}n (MII = MnII, FeII, CoII, NiII or CuII) in water and methanol, respectively. Single-crystal X-ray analyses revealed the absence of open metal sites in {MII[PtIV(SCN)6]}ns and the formation of potential open metal sites at the MII ions of {[MII(CH3OH)2][PtIV(SCN)6]}ns by the coordination of methanol. One of the two coordinating methanol molecules in {[CoII(CH3OH)2][PtIV(SCN)6]}n was replaced with pyridine to stabilise the open metal sites, because the methanol molecules are too labile to maintain open metal sites in water. The heterogeneous catalysis of coordination polymers with and without open metal sites was examined for organophosphate hydrolysis and photocatalytic water oxidation to clarify the requisites for heterogeneous catalysts.
The α-Deuterium Secondary Kinetic Isotope Effect upon the Hydrolysis of 2-(p-Nitrophenoxy)tetrahydropyran and its Relationship to Values for the Solvolysis of Secondary Alkyl Arenesulfonates and the Enzyme-catalysed Hydrolysis of Acetals
Lee, Won Heui,Maskill, H.,Manneer, Iain D.
, p. 503 - 504 (1993)
The α-deuterium secondary kinetic isotope effect for the uncatalysed hydrolysis of 2-(p-nitrophenoxy)tetrahydropyran is 1.17 in water (46 deg C), a result which is very similar to values for the solvolysi of simple secondary alkyl arenesulfonates which proceed with rate-limiting ionization and appreciably higher than results for enzyme-catalysed hydrolysis of other acetals.
Influence of temperature on the reactivity of phosphorus acid esters in reverse micellar systems based on sodium bis(2-ethylhexyl)sulfosuccinate
Zakharova,Ibragimova,Valeeva,Zakharov,Kudryavtseva,Konovalov,Zakharchenko,Zuev
, p. 1449 - 1457 (2005)
A change in the reactivity of ethyl p-nitrophenyl chloromethylphosphonate in the sodium bis(2-ethylhexyl)sulfosuccinate-n-nonane-water system around the percolation threshold was found. Study of location sites of the reactants by NMR self-diffusion and optical spectroscopy and modeling of the kinetic data in terms of the pseudophase approach demonstrated that below the percolation threshold, the reaction occurs in the surface layer. The observed rate constant for substrate hydrolysis in a microemulsion below the percolation threshold is described by the Arrhenius equation, like that in aqueous solutions. Above the percolation threshold, the slope of the Arrhenius plot sharply changes, which is apparently due to a change in the reactant location pattern and, hence, the microscopic properties of the medium in the region of their solubilization.
Reactivity differences of O-aryl O-(4-nitrophenyl) thionocarbonates versus their homolog carbonates: Micellar catalysis in hydrolysis reactions
Santos, José G.,Aliaga, Margarita E.,Márquez, Mariana F.,Oyarzún, Mauricio
, (2018)
The alkaline hydrolysis reaction of O-(4-cyanophenyl), O-(4-methylphenyl), and phenyl O-(4-nitrophenyl) thionocarbonates (1, 2, and 3, respectively) and O-(4-cyanophenyl) and phenyl O-(4-nitrophenyl) carbonates (4 and 5, respectively) has been spectrophotometrically studied in aqueous borate buffer media, in the presence of the cationic surfactant CTAB. The pseudophase model successfully explained the results obtained, in the presence of this cationic micelle, and various kinetic parameters were determined. Results show that the catalytic efficiency increases in carbonates and thionocarbonates. In fact, a catalytic efficiency ( kobsmax/k'w) of 485-fold was found in the hydrolysis reaction of thionocarbonate 1, while in the carbonate homolog 4, the effect was of 146-fold. In addition, we found that at the same experimental conditions (Borate buffer pH = 9.0 and 25°C), an increase in the concentration of the buffer led to a decrease of the hydrolysis rate.
SOLVENT EFFECT ON THE RATE OF ESTER INTERCHANGE OF p-NITROPHENYLDIETHYLPHOSPHATE
Bel'skii, V. E.,Valeeva, F. G.,Kudryavtseva, L. A.,Ivanov, B. E.
, p. 1738 - 1741 (1991)
The reaction of p-nitrophenyldiethylphosphate with sodium phenolate takes place readily in aprotic polar solvents.Bimolecular rate constants of this reaction increase with increased concentration of the phenolate in such solvents as dimethylsulfoxide (DMSO), dimethylformamide (DMF), or hexamethylphosphoric amide (HMPA), but decrease in acetonitrile or acetone; this is caused by the association of sodium phenolate, and the different reactivities of free ions and ion pairs.The addition of 18-crown-6 to the reaction mixture decreases the reaction rate, because of the reduced reactivity of the complex formed by the crown ether with the phenolate ion pair.
Polyphenol-grafted collagen fiber as reductant and stabilizer for one-step synthesis of size-controlled gold nanoparticles and their catalytic application to 4-nitrophenol reduction
Wu, Hao,Huang, Xin,Gao, Mingming,Liao, Xuepin,Shi, Bi
, p. 651 - 658 (2011)
A facile method for one-step synthesis of size-controlled gold nanoparticles (AuNPs) supported on collagen fiber (CF) at room temperature was proposed. Epigallocatechin-3-gallate (EGCG), a typical plant polyphenol, was grafted onto CF surface to serve as reducing/stabilizing agent, so that the AuNPs were generated on CF surface without introduction of extra chemical reagents or physical treatments. The prepared AuNPs were fully characterized, and the results showed that the dispersed AuNPs were successfully produced and the mean particle size of AuNPs could be effectively controlled in range of 18 to 5 nm simply by varying the grafting degree of EGCG on CF surface. These stabilized AuNPs were found to be active heterogeneous catalysts for the reduction of 4-nitrophenol to 4-aminophenol in aqueous phase. The catalytic behaviors of AuNPs depended on the particle size and the grafting degree of EGCG. A distinct advantage of these catalysts is that they can be easily recovered and reused at least twenty times, because of the high stability of the AuNPs supported by EGCG-grafted CF. The Royal Society of Chemistry.
Kinetics of the micellar nucleophilic cleavage of diastereomeric phosphotriesters
Moss, Robert A.,Bose, Susmita
, p. 965 - 968 (1997)
Diastereomeric phosphotriesters 1 and 2 are rapidly cleaved by micellar iodosobenzoate, iodosonaphthoate, and cetyltrimethylammonium hydroperoxide; diastereoselectivity is modest.