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991.
Mechanism of Evolution of Koneramine Complexes from One‐Pot Reactions: Snapshots of Intermediates Offer Facile Routes to New Dipicolylamines 下载免费PDF全文
Sakthi Raje Nandakishor Mondivagu Manoj Chahal Prof. Ray J. Butcher Prof. Raja Angamuthu 《化学:亚洲杂志》2018,13(11):1458-1466
Koneramines (LROR′, R=Ph or Ts; R′=Me, iPr) and their complexes were found to emerge from the system of pyridine‐2‐carboxaldehyde and N‐phenyl/tosylethylenediamine when a primary or secondary alcohol was used as solvent. Imidazolidinylpyridines (LR, R=Ph or Ts) became major emergents whereas hemi‐aminals (LROH, R=Ph or Ts) are minor emergents of the system when tertiary butanol was used as the solvent; the bulky tertiary butyl group prevented the addition of alcohol to the iminium ion that diverted the equilibrium towards imidazolidinylpyridines. By playing with the components of the reaction mixture, crystals of the metastable intermediates bound to copper(II) and/or zinc(II) were obtained and the structures were determined by X‐ray diffraction analysis. The reported results shed light on how to control the emergents of the multicomponent reaction mixture that forms koneramines. Reactivity studies of the intermediates pave the way for a new type of koneramine complexes that are new dipicolylamines where the two pyridine moieties of the resulting koneramine are not the same. 相似文献
992.
Comparison of the Reactivities and Selectivities of Group 9 [Cp*MIII] Catalysts in C−H Functionalization Reactions 下载免费PDF全文
Pentamethylcyclopentadienyl (Cp*)‐based Group 9 metal (Co, Rh, or Ir) catalysts have emerged as powerful tools for C?H functionalization reactions. Whilst a diverse range of organic transformations have been developed by using [Cp*MIII] catalysts, they have often exhibited orthogonal reactivities and varied selectivities that depended on the choice of the central metal atom. An understanding of the physicochemical properties of the metals, as well as of their reaction mechanisms, has led to significant expansion of the synthetic scope of C?H functionalization reactions. This Focus Review summarizes and discusses the comparative catalytic reactivities and selectivities of the [Cp*MIII] catalysts, with an emphasis on metal‐dependent pathway‐switching by considering the mechanistic rationale. 相似文献
993.
A Multi‐Stimuli‐Responsive Oxazine Molecular Switch: A Strategy for the Design of Electrochromic Materials 下载免费PDF全文
Xiaojun Wang Chang Gu Hongzhi Zheng Dr. Yu‐Mo Zhang Prof. Sean Xiao‐An Zhang 《化学:亚洲杂志》2018,13(9):1206-1212
A multi‐state and multi‐stimuli‐responsive oxazine molecular switch that combines an electro‐base property and sensitive base/acid‐responsive properties was designed and synthesized. The multi‐state structures of the molecular switch, with different colors, were predicted by comparing the optical properties with reference molecules and confirmed by using NMR spectroscopy. The color‐switching mechanism under stimulation with acids and bases was investigated by using DFT calculations. Three single states can be obtained and the switching is unidirectional under acid and base stimulation. The electrochromic phenomenon of the molecular switch, which combines its electro‐base and base‐sensitive properties, was demonstrated. An electrochromic device that exhibited good electrochromic properties with excellent reversibility (2000 cycles) and high coloration efficiency (804 cm2 C?1) was successfully constructed. 相似文献
994.
Stable meso‐Aryl β‐Alkyl Hybrid Sapphyrin with a Warped π‐Conjugation Circuit and Neo‐Confused Sapphyrin–Silver(I) Complex 下载免费PDF全文
A meso‐aryl and β‐alkyl substituted sapphyrin and its rhodium(I) and silver complexes were synthesized. This sapphyrin was so stable that the non‐inverted and warped structure could be analyzed by X‐ray crystallography even in its neutral state. Its bis‐rhodium(I) complex has a more planar structure than the sapphyrin with enhanced aromaticity over the conjugation circuit. On the other hand, silver metalation of the sapphyrin caused a marked core rearrangement into a neo‐confused sapphyrin derivative with a C(α)?N bond and a twisted macrocycle. 相似文献
995.
Solvent‐Mediated Functionalization of Benzofuroxan on Electron‐Rich Ruthenium Complex Platform 下载免费PDF全文
Dr. Prabir Ghosh Sanchaita Dey Sanjib Panda Prof. Goutam Kumar Lahiri 《化学:亚洲杂志》2018,13(12):1582-1593
An unprecedented reactivity profile of biochemically relevant R‐benzofuroxan (R=H, Me, Cl), with high structural diversity and molecular complexity on a selective {Ru(acac)2} (acac=acetylacetonate) platform, in conjugation with EtOH solvent mediation, is revealed. This led to the development of monomeric [RuIII(acac)2(L1R)] ( 1 a – 1 c ; L1R=2‐nitrosoanilido derivatives) and dimeric [{RuII(acac)2}2(L2R)] ( 2 a – 2 b ; L2R=(1E,2E)‐N1,N2‐bis(2‐nitrosophenyl)ethane‐1,2‐diimine derivatives) complexes in one pot with a change in the metal redox conditions. The functionalization of benzofuroxan in 1 and 2 implied in situ reduction of N=O to NH? in the former and solvent‐assisted multiple N?C coupling in the latter. The aforesaid transformation processes were authenticated through structural elucidation of representative complexes, and evaluated by their spectroscopic/electrochemical features, along with C2D5OD labeling and monitoring of the impact of substituents (R) in the benzofuroxan framework on the product distribution process. The noninnocent potential of newly developed L1 and L2 in 1 and 2 , respectively, was also probed by spectroelectrochemistry in combination with DFT calculations. 相似文献
996.
Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles 下载免费PDF全文
Dr. Ken‐ichi Yamashita Takayo Yamanaka Naoya Sakata Prof. Dr. Takuji Ogawa 《化学:亚洲杂志》2018,13(13):1692-1698
Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double‐decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [TbIII(tpp)2]n (tpp: tetraphenylporphyrinato, n=?1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [TbIII(oep)2]?1 and [TbIII(oep)2]0 (oep: octaethylporphyrinato), but φ=36° for [TbIII(oep)2]+1. Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system. 相似文献
997.
Hierarchical MoS2@TiO2 Heterojunctions for Enhanced Photocatalytic Performance and Electrocatalytic Hydrogen Evolution 下载免费PDF全文
Yu Dong Sheng‐You Chen Yi Lu Yu‐Xuan Xiao Jie Hu Si‐Ming Wu Dr. Zhao Deng Prof. Ge Tian Prof. Gang‐Gang Chang Prof. Jing Li Prof. Silvia Lenaerts Prof. Christoph Janiak Prof. Xiao‐Yu Yang Prof. Bao‐Lian Su 《化学:亚洲杂志》2018,13(12):1609-1615
Hierarchical MoS2@TiO2 heterojunctions were synthesized through a one‐step hydrothermal method by using protonic titanate nanosheets as the precursor. The TiO2 nanosheets prevent the aggregation of MoS2 and promote the carrier transfer efficiency, and thus enhance the photocatalytic and electrocatalytic activity of the nanostructured MoS2. The obtained MoS2@TiO2 has significantly enhanced photocatalytic activity in the degradation of rhodamine B (over 5.2 times compared with pure MoS2) and acetone (over 2.8 times compared with pure MoS2). MoS2@TiO2 is also beneficial for electrocatalytic hydrogen evolution (26 times compared with pure MoS2, based on the cathodic current density). This work offers a promising way to prevent the self‐aggregation of MoS2 and provides a new insight for the design of heterojunctions for materials with lattice mismatches. 相似文献
998.
Electrodeposited Amorphous Tungsten‐doped Cobalt Oxide as an Efficient Catalyst for the Oxygen Evolution Reaction 下载免费PDF全文
Linh N. Nguyen Dr. Ung Thi Dieu Thuy Dr. Quang Duc Truong Prof. Itaru Honma Prof. Quang Liem Nguyen Dr. Phong D. Tran 《化学:亚洲杂志》2018,13(12):1530-1534
Thin film of amorphous tungsten‐doped cobalt oxide (W:CoO) was successfully grown on a conducting electrode via an electrochemical oxidation process employing a [Co(WS4)2]2? deposition bath. The W:CoO catalyst displays an attractive performance for the oxygen evolution reaction in an alkaline solution. In an NaOH solution of pH 13, W:CoO operates with a moderate onset overpotential of 230 mV and requires 320 mV overpotential to generate a catalytic current density of 10 mA cm?2. A low Tafel slope of 45 mV decade?1 was determined, indicating a rapid O2‐evolving kinetics. The as‐prepared W:CoO belongs to the best cobalt oxide‐based catalysts ever reported for the oxygen evolution (OER) reaction. 相似文献
999.
An Unconventional Polymerization Route to Hydrophilic Fluorescent Organic Nanoparticles for Multicolor Cellular Bioimaging 下载免费PDF全文
Qingfu Ban Yinglai Hou Dr. Wen Sun Dr. Jianxin Chen Xiaofei Zhang Dr. Si Wu Prof. Jie Kong 《化学:亚洲杂志》2018,13(12):1625-1631
We demonstrated an unconventional polymerization route to synthesize hydrophilic fluorescent organic nanoparticles (FONs) for multicolor cellular bioimaging in this contribution. The route benefits from our unexpected discovery of a rapid polymerization reaction between 1,6‐hexanediol dipropiolate and 2,4,6‐triazide‐1,3,5‐triazine under the catalysis of N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine (PMDETA). Interestingly, the 2,4,6‐triazide‐1,3,5‐triazine and PMDETA system can also induce rapid free radical polymerization at room temperature. The as‐prepared FONs exhibited promising water solubility and stability with an average diameter of 20 nm. The excitation wavelength‐dependent fluorescent properties endow the FONs with blue, yellow, and red fluorescent emission under UV, blue, and green excitation, respectively. The cytotoxicity of FONs was investigated by using a Cell Counting Kit (CCK‐8) assay, which indicated good biocompatiblity. More importantly, the cell uptake experiment verified the FONs were excellent fluorescent nanoprobes for multicolor cellular bioimaging. Therefore, this unconventional route provides a novel fabrication strategy of highly hydrophilic FONs for biomedical applications. 相似文献
1000.
Hydroarylation of bicyclic alkenes has been developed using a low‐valent ReI‐catalyzed, directing group‐assisted C?H bond activation strategy. The addition of sodium acetate significantly improves the reaction efficiency; moreover, bicyclic alkenes such as 7‐oxa and aza benzonorbornadienes worked efficiently under this reaction condition. Preliminary mechanistic studies suggest that, after the alkene insertion, the rhenacycle preferentially undergoes protonolysis rather than reductive elimination. 相似文献