91117-61-2Relevant articles and documents
A Thioether-Ligated Cupric Superoxide Model with Hydrogen Atom Abstraction Reactivity
Bhadra, Mayukh,Transue, Wesley J.,Lim, Hyeongtaek,Cowley, Ryan E.,Lee, Jung Yoon C.,Siegler, Maxime A.,Josephs, Patrick,Henkel, Gerald,Lerch, Markus,Schindler, Siegfried,Neuba, Adam,Hodgson, Keith O.,Hedman, Britt,Solomon, Edward I.,Karlin, Kenneth D.
supporting information, p. 3707 - 3713 (2021/04/06)
The central role of cupric superoxide intermediates proposed in hormone and neurotransmitter biosynthesis by noncoupled binuclear copper monooxygenases like dopamine-β-monooxygenase has drawn significant attention to the unusual methionine ligation of the CuM ( CuB ) active site characteristic of this class of enzymes. The copper-sulfur interaction has proven critical for turnover, raising still-unresolved questions concerning Nature's selection of an oxidizable Met residue to facilitate C-H oxygenation. We describe herein a model for CuM, [(TMGN3S)CuI]+ ([1]+), and its O2-bound analog [(TMGN3S)CuII(O2?-)]+ ([1·O2]+). The latter is the first reported cupric superoxide with an experimentally proven Cu-S bond which also possesses demonstrated hydrogen atom abstraction (HAA) reactivity. Introduction of O2 to a precooled solution of the cuprous precursor [1]B(C6F5)4 (-135 °C, 2-methyltetrahydrofuran (2-MeTHF)) reversibly forms [1·O2]B(C6F5)4 (UV/vis spectroscopy: λmax 442, 642, 742 nm). Resonance Raman studies (413 nm) using 16O2 [18O2] corroborated the identity of [1·O2]+ by revealing Cu-O (446 [425] cm-1) and O-O (1105 [1042] cm-1) stretches, and extended X-ray absorption fine structure (EXAFS) spectroscopy showed a Cu-S interatomic distance of 2.55 ?. HAA reactivity between [1·O2]+ and TEMPO-H proceeds rapidly (1.28 × 10-1 M-1 s-1, -135 °C, 2-MeTHF) with a primary kinetic isotope effect of kH/kD = 5.4. Comparisons of the O2-binding behavior and redox activity of [1]+ vs [2]+, the latter a close analog of [1]+ but with all N atom ligation (i.e., N3S vs N4), are presented.
Enhancing the photocatalytic efficiency of the BiOCl/Bi3O4Cl composite modified with WO3for environmental purification under visible light
Chakraborty, Ashok Kumar,Ganguli, Sumon,Bera, Sandipan
, p. 17617 - 17629 (2021/10/04)
Covering the BiOCl/Bi3O4Cl composite with a monolayer of WO3resulted in a significant increase in the photocatalytic activity of WO3/BiOCl/Bi3O4Cl in the presence of visible light (?= 420 nm). The decomposition of gaseous isopropyl alcohol (IPA) and aqueous salicylic acid (SA) in the presence of visible light was maximized when 0.2 mol% of WO3was attached to the surface of BiOCl/Bi3O4Cl. However, while the amount of WO3on the surface of BiOCl/Bi3O4Cl was less or more than 0.2 mol%, the photocatalytic activity was found to be abruptly reduced. At this composition, WO3/BiOCl/Bi3O4Cl demonstrated 2.1 and 5.2 times better activity than the BiOCl/Bi3O4Cl composite and Degussa P25 (TiO2nanoparticle) for evolving CO2from the decomposition of IPA in gas phase under the identical conditions. These results suggest that 0.2 mol% WO3/BiOCl/Bi3O4Cl was the optimized composition to achieve the highest photocatalytic activity covering of BiOCl/Bi3O4Cl through the formation of a monolayer by molecular WO3. On the surface of BiOCl/Bi3O4Cl, the function of WO3is to offer increasing OH-, H2O or organics towards WO3/BiOCl/Bi3O4Cl by increasing the adsorption affinity of WO3/BiOCl/Bi3O4Cl. Furthermore, the chemical durability of BiOCl/Bi3O4Cl was increased due to the covering of BiOCl/Bi3O4Cl with WO3. Considering the above findings, the role of WO3in enhancing the photocatalytic efficiency of BiOCl/Bi3O4Cl has been explained in detail.
High electron transfer of TiO2nanorod@carbon layer supported flower-like WS2nanosheets for triiodide electrocatalytic reduction
Wang, Wei,Liu, Tianyu,Ding, Chuan,Wang, Min,Bai, Jirong,Zhang, Jintao,Bi, Hengchang,Sun, Yueming,Wang, Yuqiao
, p. 3387 - 3391 (2021/03/03)
WS2-based nanomaterials have been extensively studied due to their unique catalytic properties. However, it is still a great challenge to prepare WS2-based electrocatalysts with both maximally active edge sites exposure and high electronic conductivity. In this work, we have engineered a 1D-2D multidimensional nanostructured TiO2 nanorod@carbon layer supported flower-like WS2 nanosheets (TNRs@C@WS2) electrocatalyst with abundant exposed active edge sites as well as high electron transfer abilities. The TNRs@C@WS2 was explored as a good catalyst for the triiodide reduction reaction. The assembled dye-sensitized solar cell achieves a high photoelectric conversion efficiency (7.15%) and comparable to that (7.18%) of Pt. This unique 1D-2D multidimensional nanostructure may open up new opportunities for a variety of applications in clean energy and catalysis.
Synthesis and spectroscopic characterization of ternary copper(ii) complexes containing nitrogen and oxygen donors as functional mimics of catechol oxidase and phenoxazinone synthase
Abdel-Rahman, Adel A.-H.,Al-Harbi, Sami A.,Ibrahim, Mohamed M.,Omar, Walid,Ramadan, Abd El-Motaleb M.,Sallam, Shehab A.,Shaban, Shaban Y.
, p. 6331 - 6345 (2020/05/13)
Two ternary copper(ii) complexes 1 [(Cu2Me4en)4(EDTA)] and 2 [(CuMe4en)2(MIDA)] containing the mixed ligand system of 1,1′,4,4′-tetramethylethylenediamine (Me4en) (L) and N-methyliminodiace
Preparation of CdS/BiOCl/Bi2O3 double composite system for visible light active photocatalytic applications
Chakraborty, Ashok Kumar,Ganguli, Sumon,Bera, Sandipan,Lee, Wan In
, p. 159 - 168 (2018/06/14)
An efficient visible-light-harvesting (λ ≥ 420 nm) three component system heterojunction photocatalyst, CdS/BiOCl/Bi2O3 was prepared by anchoring of CdS nanoparticles on the surface of BiOCl/Bi2O3 composite. The effect of CdS nanoparticles on the surface of BiOCl/Bi2O3 composite photocatalyst had been justified in enhancing photocatalytic activity towards the degradation of organic pollutants in gas as well as aqueous phase. With the loading of CdS on to the BiOCl/Bi2O3 heterojunction composite photocatalyst, the photocatalytic activity of the CdS/BiOCl/Bi2O3 composite structure has been appreciably improved for the decomposition of 2-propanol (IPA) in gas phase and salicylic acid (SA) in aqueous phase under visible light irradiation (λ ≥ 420 nm). The amount of loading of CdS nanoparticles was optimized to 2 mol% CdS/BiOCl/Bi2O3. Compare to bare BiOCl/Bi2O3 photocatalyst, CdS/BiOCl/Bi2O3 heterojunction demonstrated 2 times decomposition of IPA in gas phase and 1.8 times of SA in aqueous phase after 120 min. of visible light irradiation. At the same time, with this composition the evolution of CO2 from degradation of IPA was 1.9 times higher than that of BiOCl/Bi2O3 composite. The enhanced photocatalytic efficiency is deduced from the electron (eˉ) and hole (h+) transfer among the component semiconductor nanoparticles Bi2O3, BiOCl and CdS due to their relative energy band positions. Several experimental evidences were also provided to confirm the electron-hole transfer among the semiconductors and a mechanistic way has been proposed.
Synthesis, structural and magnetic characterizations of a dinuclear copper(II) complex with an (N,S,O) donor ligand: Catecholase and phenoxazinone synthase activities
Ghosh, Ayon Kanti,Ali, Anzar,Singh, Yogesh,Purohit, Chandra Shekhar,Ghosh, Rajarshi
, p. 156 - 163 (2018/02/20)
A new dinuclear Cu(II) complex (1) was synthesized and crystallographically characterized. Each of the Cu(II) centres has penta coordination and been found to adopt square pyramidal geometry. Variable temperature magnetic measurements showed that there is weak ferromagnetic interaction between the Cu(II) centres in 1. 1 shows catecholase as well as phenoxazinone synthase activities in different solvents. The turn over numbers for the catecholase activity were 4.02 × 103 h?1 (MeOH) and 9.57 × 103 h?1 (MeCN), and that of phenoxazinone synthase activity were 1.065 × 103 h?1 (MeOH), 2.13 × 102 h?1 (MeCN) and 2.844 × 103 h?1 (DCM).
snorkelling : Vs. diving in mixed micelles probed by means of a molecular bathymeter
Rodriguez-Mu?iz, Gemma M.,Gomez-Mendoza, Miguel,Nuin, Edurne,Andreu, Inmaculada,Marin, M. Luisa,Miranda, Miguel A.
supporting information, p. 10281 - 10288 (2017/12/26)
A photoactive bathymeter based on a carboxylic acid moiety covalently linked to a signalling methoxynaphthalene (MNP) fluorophore has been designed to prove the concept of snorkelling vs. diving in mixed micelles (MM). The carboxylic acid floats on the MM surface, while the MNP unit sinks deep in MM. The rate constants of MNP fluorescence quenching by iodide, which remains basically in water, consistently decrease with increasing spacer length, revealing different regions. This is associated with the distance MNP should dive in MM to achieve protection from aqueous reactants. Unequivocal proof of the exergonic photoinduced electron transfer was obtained from the UV-visible spectral signature of I3- upon steady-state photolysis. The applicability of the bathymeter was examined upon testing a family of MNP derivatives. The obtained results were validated by comparison with different lipophilicity tests: (i) a modified version of the Kow partition coefficient and (ii) the retention factor on thin layer chromatography. This concept could potentially be extended to test drugs or pharmacophores exhibiting any photoactive moiety.
Peptide-induced hierarchical long-range order and photocatalytic activity of porphyrin assemblies
Liu, Kai,Xing, Ruirui,Chen, Chengjun,Shen, Guizhi,Yan, Linyin,Zou, Qianli,Ma, Guanghui,M??hwald, Helmuth,Yan, Xuehai
supporting information, p. 500 - 505 (2015/03/05)
Long-range structural order and alignment over different scales are of key importance for the regulation of structure and functionality in biology. However, it remains a great challenge to engineer and assemble such complex functional synthetic systems with order over different length scales from simple biologically relevant molecules, such as peptides and porphyrins. Herein we describe the successful introduction of hierarchical long-range order in dipeptide-adjusted porphyrin self-assembly by a thermodynamically driven self-orienting assembly pathway associated with multiple weak interactions. The long-range order and alignment of fiber bundles induced new properties, including anisotropic birefringence, a large Stokes shift, amplified chirality, and excellent photostability as well as sustainable photocatalytic activity. We also demonstrate that the aligned fiber bundles are able to induce the epitaxially oriented growth of Pt nanowires in a photocatalytic reaction.
Mechanism and scope of the base-induced dehalogenation of (E)-diiodoalkenes
Resch, Daniel,Lee, Chang Heon,Tan, Siew Yoong,Luo, Liang,Goroff, Nancy S.
, p. 730 - 737 (2015/01/30)
A wide range of nucleophiles have induced the elimination of iodine from (E)-diiodoalkenes to form alkynes under surprisingly mild conditions. The iodide anion is particularly efficient, and can drive the reaction to completion in less than 1 hour at room temperature in a polar aprotic solvent. Detailed investigations have suggested the reaction has a bimolecular polar mechanism. The deiodination reaction can be driven to completion with 1 equiv. of nucleophile and is partially catalytic with substoichiometric amounts of deiodinating reagent. Kinetic analysis of the stoichiometric iodide-induced reaction indicated an overall pseudo-first-order behavior. The reaction exhibited strong solvent effects, with much slower reactions observed in protic solvents than in polar aprotic solvents. The substrate dimethyl (2E)-2,3-diiodo-butene-2-dioate demonstrated orthogonal reactivity for either elimination or hydrolysis, depending on the solvent and nucleophile used. This reaction is a major pathway for all the diiodoalkenes examined, and represents a challenge and an opportunity for using these substrates in organic synthesis.
The effect of hydroxycinnamic acids on oxy-radical generating iodide-hydrogen peroxide reaction
Milenkovi, Maja C.,Potkonjak, Neboja I.
, p. 1255 - 1259 (2015/02/19)
The influence of hydroxycinnamic acids (HCA) on the oxy-radical generated system, potassium iodide/hydrogen peroxide, was investigated through the enhancement of triiodide (I3-) yield. Caffeic acid, chlorogenic acid, and p-coumaric acid were used as typical representatives of HCA. A linear correlation, with positive slopes, was found between absorption maximum of I3- at 351 nm and HCA concentration in all cases. The magnitude of enhanced I3- production was found to increase in the following order: p-coumaric acid A reaction mechanism, which includes negative influence of oxygen-centered free radicals on the I3- yield, was proposed. The enhanced production of I3- by HCA is attributed to their radical scavenging activity. Supported by literature data, results obtained in this study have showed the correlation between radical scavenging activities of HCA and their ability to enhanced I3- generation.
