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101.
102.
Isotachophoresis (ITP) has long been used alone but also as a preconcentration technique for capillary electrophoresis (CE). Unfortunately, up to now, its application is restricted to relatively strong acids and bases as either the degree of (de)protonation is too low or the water dissociation is too high, evoking zone electrophoresis. With the comprehensive ITP analysis of all 20 proteinogenic amino acids as model analytes, we, here, show that non–aqueous ITP using dimethylsulfoxide as a solvent solves this ITP shortcoming. Dimethylsulfoxide changes the pH regime of analytes and electrolytes but, more importantly, strongly reduces the proton mobility by prohibiting hydrogen bonds and thus, the so-called Zundel–Eigen–Zundel electrical conduction mechanism of flipping hydrogen bonds. The effects are demonstrated in an electrolyte system with taurine or H+ as terminator, and imidazole as leader together with strong acids such as oxalic and even trifluoroacetic acid as counterions, both impossible to use in aqueous solution. Mass spectrometric as well as capacitively coupled contactless conductivity detection (C4D) are used to follow the ITP processes. To demonstrate the preconcentration capabilities of ITP in a two-dimensional set-up, we, here, also demonstrate that our non-aqueous ITP method can be combined with capillary electrophoresis–mass spectrometry in a column-coupling system using a hybrid approach of capillaries coupled to a microfluidic interface. For this, C4D was optimized for on-chip detection with the electrodes aligned on top of a thin glass lid of the microfluidic chip. 相似文献
103.
Copper(I)‐Catalyzed Regioselective Addition of Nucleophilic Silicon Across Terminal and Internal Carbon–Carbon Triple Bonds
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The copper(I) alkoxide‐catalyzed release of a silicon‐based cuprate reagent from a silicon–boron pronucleophile is applied to the addition across carbon–carbon triple bonds. Commercially available CuBr?Me2S was found to be a general precatalyst that secures high regiocontrol for both aryl‐ and alkyl‐substituted terminal as well as internal alkynes. The solvent greatly influences the regioisomeric ratio, favoring the linear regioisomer with terminal acceptors. This facile protocol even allows for the transformation of internal acceptors with remarkable levels of regio‐ and diastereocontrol. 相似文献
104.
105.
Dr. Carolin Müller Alexander Schwab Dr. Nicholas M. Randell Dr. Stephan Kupfer Prof. Benjamin Dietzek-Ivanšić Dr. Murielle Chavarot-Kerlidou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(18):e202103882
The design of photoactive systems capable of storing and relaying multiple electrons is highly demanded in the field of artificial photosynthesis, where transformations of interest rely on multielectronic redox processes. The photophysical properties of the ruthenium photosensitizer [(bpy)2Ru( oxim-dppqp )]2+ ( Ru ), storing two electrons coupled to two protons on the π-extended oxim-dppqp ligand under light-driven conditions, are investigated by means of excitation wavelength-dependent resonance Raman and transient absorption spectroscopies, in combination with time-dependent density functional theory; the results are discussed in comparison to the parent [(bpy)2Ru(dppz)]2+ and [(bpy)2Ru( oxo-dppqp )]2+ complexes. In addition, this study provides in-depth insights on the impact of protonation or of accumulation of multiple reducing equivalents on the reactive excited states. 相似文献
106.
Dong Yunzhao Li Tingcheng You Xiangqian You Qingliang Sun Lang Xie Guangyong 《Research on Chemical Intermediates》2022,48(3):1151-1158
Research on Chemical Intermediates - Dichlorobenzonitriles are important organic intermediates for the production of many fine chemicals and are produced most economically and environment-friendly... 相似文献
107.
Jannik Brückmann Dr. Carolin Müller Tamar Maisuradze Dr. Alexander K. Mengele Dr. Djawed Nauroozi Sven Fauth Andreas Gruber Prof. Dr. Stefanie Gräfe Prof. Dr. Kerstin Leopold Dr. Stephan Kupfer Prof. Dr. Benjamin Dietzek-Ivanšić Prof. Dr. Sven Rau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(51):e202200766
The synthesis and detailed characterization of a new Ru polypyridine complex containing a heteroditopic bridging ligand with previously unexplored metal-metal distances is presented. Due to the twisted geometry of the novel ligand, the resultant division of the ligand in two distinct subunits leads to steady state as well as excited state properties of the corresponding mononuclear Ru(II) polypyridine complex resembling those of prototype [Ru(bpy)3]2+ (bpy=2,2'-bipyridine). The localization of the initially optically excited and the nature of the long-lived excited states on the Ru-facing ligand spheres is evaluated by resonance Raman and fs-TA spectroscopy, respectively, and supported by DFT and TDDFT calculations. Coordination of a second metal (Zn or Rh) to the available bis-pyrimidyl-like coordination sphere strongly influences the frontier orbitals, apparent by, for example, luminescence quenching. Thus, the new bridging ligand motif offers electronic properties, which can be adjusted by the nature of the second metal center. Using the heterodinuclear Ru−Rh complex, visible light-driven reduction of NAD+ to NADH was achieved, highlighting the potential of this system for photocatalytic applications. 相似文献
108.
Jannik Brückmann Dr. Carolin Müller Ilse Friedländer Dr. Alexander K. Mengele Prof. Kalina Peneva Prof. Benjamin Dietzek-Ivanšić Prof. Sven Rau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(61):e202201931
The ambitious goal of artificial photosynthesis is to develop active systems that mimic nature and use light to split water into hydrogen and oxygen. Intramolecular design concepts are particularly promising. Herein, we firstly present an intramolecular photocatalyst integrating a perylene-based light-harvesting moiety and a catalytic rhodium center ( RhIIIphenPer ). The excited-state dynamics were investigated by means of steady-state and time-resolved absorption and emission spectroscopy. The studies reveal that photoexcitation of RhIIIphenPer yields the formation of a charge-separated intermediate, namely RhIIphenPer ⋅ + , that results in a catalytically active species in the presence of protons. 相似文献
109.
Jiawang Liu Carolin Schneider Ji Yang Zhihong Wei Haijun Jiao Robert Franke Ralf Jackstell Matthias Beller 《Angewandte Chemie (International ed. in English)》2021,60(1):371-379
A chemo‐, regio‐, and stereoselective mono‐hydroamidation of (un)symmetrical 1,3‐diynes is described. Key for the success of this novel transformation is the utilization of an advanced palladium catalyst system with the specific ligand Neolephos. The synthetic value of this general approach to synthetically useful α‐alkynyl‐α, β‐unsaturated amides is showcased by diversification of several structurally complex molecules and marketed drugs. Control experiments and density‐functional theory (M06L‐SMD) computations also suggest the crucial role of the substrate in controlling the regioselectivity of unsymmetrical 1,3‐diynes. 相似文献
110.
Sren Arlt Vladana Petkovi Gerd Ludwig Thomas Eichhorn Heinrich Lang Tobias Rüffer Sanja Mijatovi Danijela Maksimovi-Ivani Goran N. Kaluerovi 《Molecules (Basel, Switzerland)》2021,26(7)
Neutral [Ru(η6-arene)Cl2{Ph2P(CH2)3SPh-κP}] (arene = benzene, indane, 1,2,3,4-tetrahydronaphthalene: 2a, 2c and 2d) and cationic [Ru(η6-arene)Cl(Ph2P(CH2)3SPh-κP,κS)]X complexes (arene = mesitylene, 1,4-dihydronaphthalene; X = Cl: 3b, 3e; arene = benzene, mesitylene, indane, 1,2,3,4-tetrahydronaphthalene, and 1,4-dihydronaphthalene; X = PF6: 4a–4e) complexes were prepared and characterized by elemental analysis, IR, 1H, 13C and 31P NMR spectroscopy and also by single-crystal X-ray diffraction analyses. The stability of the complexes has been investigated in DMSO. Complexes have been assessed for their cytotoxic activity against 518A2, 8505C, A253, MCF-7 and SW480 cell lines. Generally, complexes exhibited activity in the lower micromolar range; moreover, they are found to be more active than cisplatin. For the most active ruthenium(II) complex, 4b, bearing mesitylene as ligand, the mechanism of action against 8505C cisplatin resistant cell line was determined. Complex 4b induced apoptosis accompanied by caspase activation. 相似文献