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排序方式: 共有190条查询结果,搜索用时 46 毫秒
1.
Dr. Benson Joseph Suman Gomosta Dr. Rini Prakash Dr. Thierry Roisnel Prof. Ashwini K. Phukan Prof. Sundargopal Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16824-16832
Treatment of Li[BH3ER] (E=Se or Te, R=Ph; E=S, R=CH2Ph) with [Cp*CoCl]2 led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ-EPh}{μ-κ2-E,H-EBH3}], 1a and 1 b ( 1 a : E=Se; 1 b : E=Te) and a bis-hydridoborate species [Cp*Co{μ-κ2-Se,H-SeBH3}]2, 2 . All the complexes, 1 a , 1 b and 2 are stabilized by β-agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B−Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B-chalcogen and Co-chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ3-E,H,H-E(BH2)2-C5Me5H3}], 3 a and 3 b ( 3 a : E=Se and 3 b : E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.02,4.03,5]nonane having identical structure and similar valence electron counts. 相似文献
2.
Carsten Lenczyk Dr. Dipak Kumar Roy Bijoy Ghosh Johannes Schwarzmann Prof. Ashwini K. Phukan Prof. Dr. Holger Braunschweig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8585-8589
A series of bis(σ)-borane complexes of Group 6 transition metals were prepared by direct dihydroborane coordination to the metal center. Reaction of [M(CO)3(PCy3)2] and two dihydroboranes [DurBH2] and [(Me3Si)2NBH2] (Dur=2,3,5,6-Me4C6H) yielded bis(σ)-borane complexes fac-[M(CO)3(PCy3){η2-(H2BR)}] (R=Dur; 1 : M=Cr, 2 : M=W; R=N(SiMe3)2; 3 : M=Cr, 4 : M=W). In the case of molybdenum, we have isolated an arene complex ( 5 ) with [DurBH2] in which the Dur group acts as a η6-bound ligand, and with [(Me3Si)2NBH2] a similar bis(σ)-borane complex was isolated, cis,trans-[Mo(CO)2(PCy3)2{η2-(H2BN(SiMe3)2}] ( 6 ), with a different pattern of auxiliary ligands. The complexes were investigated by multinuclear NMR spectroscopy, mass spectrometry, X-ray diffraction analysis, and computational methods. Quantum theory of atoms in molecules (QTAIM) calculations demonstrated that the borane complexes may be described as pure bis(σ)-borane complexes rather than elongated or stretched examples given that the calculations do not show the presence of a ring-critical point (RCP) at the ring formed by the interactions of the B−H with metal center. 相似文献
3.
Bitupon Borthakur Prof. Ashwini K. Phukan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11603-11609
The effect of ylide substitution at the α position to the carbene carbon (Cc) atom on the stability and σ‐donating ability of a number of cyclic carbenes has been studied theoretically. The stabilities of all of the carbenes were investigated from an evaluation of their singlet–triplet energy gaps and stabilization energies. All carbenes were found to have a stable singlet state. The energy of the σ‐symmetric lone‐pair orbital at the Cc atom increases as a result of the introduction of ylide centers near to the Cc atom. This indicates an enhanced σ‐donating ability of the ylide‐containing carbenes. The calculated carbonyl‐stretching frequencies of the corresponding rhodium complexes, proton affinities, and nucleophilicity index values correlate well with the σ basicity of the carbenes. 相似文献
4.
A facile method for the synthesis of silver-silica(Ag-SiO2) Janus particles with functionalities suitable for textile applications is reported.Silica nanoparticles prepared by the Stober method were functionalized with epoxy,amine,and thiol groups,which were confirmed by Fourier transform infrared analysis.The functionalized silica nanoparticles were used to produce Pickering emulsions,and the exposed surface was used for the attachment of silver nanoparticles(AgNPs) via the low-temperature chemical reduction method.The morphology and structure of the Ag-SiO2 Janus particles were characterized by scanning electron microscopy,scanning transmission electron microscopy,high-resolution transmission electron microscopy,energy-dispersive X-ray analysis,and UV-vis spectroscopy.Because of their specific functionalities,these Ag-SiO2 Janus particles are proposed for applications on textile substrates,as they can overcome several drawbacks of direct application of AgNPs on textiles,such as leaching,agglomeration,and instability during storage. 相似文献
5.
Prof. Dr. Holger Braunschweig Dr. Rian D. Dewhurst Dipl.‐Chem. Christian Hörl Dr. Ashwini K. Phukan Florian Pinzner Stefan Ullrich 《Angewandte Chemie (International ed. in English)》2014,53(12):3241-3244
Synthetic access to electron‐precise boron chains is hampered by the preferential formation of nonclassical structures. The few existing strategies for this involve either strongly reducing reagents or transition‐metal catalysts, both with distinct disadvantages. The synthesis of new furyl‐ and thienyl‐substituted diborenes is presented, along with their direct hydroboration with catecholborane (CatBH) to form a new electron‐precise B? B bond and a B3 chain. The reaction is diastereoselective and proceeds under mild conditions without the use of strong reducing agents or transition‐metal catalysts commonly used in B‐B coupling reactions. 相似文献
6.
7.
Deshpande Deepti Gadmale Dinesh Bakre Suhas Srivastava Ashwini Kumar 《平面色谱法杂志一现代薄层色谱法》2016,29(6):429-434
JPC – Journal of Planar Chromatography – Modern TLC - In an attempt to determine chlorpyrifos insecticide and its metabolite 3,5,6-trichloropyridinol in visceral samples, a rapid... 相似文献
8.
In this paper, a highly selective Sudan IV molecularly imprinted polymer was synthesized by surface molecular imprinting technique in combination with a sol?Cgel process using ??-aminopropyl triethoxysilane as functional monomer, tetraethoxysilane as cross-linker and activated silica gel as support material. The imprinted polymer was characterized by FT-IR spectra, scanning electron micrograph and adsorption experiments and it was exhibited good recognition and selective ability, offered a faster rate for the adsorption of Sudan IV. Using the imprinted material as sorbent, a solid-phase extraction coupled with high-performance liquid chromatography method for determination of trace Sudan IV was presented. The detection limit (S/N = 3) was 25.2 ng L?1, and the RSD for five replicate was 2.86%. With a loading flow rate of 2.5 mL min?1 for loading 30 mL, an enrichment factor of 104 was achieved. This method was applied for extraction and determination of chilli powder and duck egg samples with good recoveries ranging from 85.3 to 98.1%. 相似文献
9.
K. Kasi Amarnath Reddy Smriti Moi Ashwini Dolle Basavaprabhu Hosamani Kiran Krishnamurthy Sunita Prakash Srinivasarao Raghothama Konkallu Hanumae Gowd 《Helvetica chimica acta》2020,103(7):e2000062
Dimedone is the most widely used chemical probe for detection of cysteine sulfenic acid in peptides and proteins. The reaction of dimedone with cysteine sulfenic acid results in the formation of unique cysteine dimedone motif containing thioether bridge. Based on the structure of cysteine dimedone residue in polypeptide, a new building block of Fmoc-Cys(Dmd)-OH was developed for solid phase synthesis of peptide cysteine dimedone. Mass spectrometric sequencing of synthetic peptides have confirmed successful incorporation of cysteine dimedone in peptide chain using HBTU/HOBt as a coupling agent. The new method permits synthesis of peptides containing both cysteine thiol and cysteine dimedone in the same sequence which was difficult to achieve by conventional methods. The synthetic peptide of glutathione cysteine dimedone was used as a standard in probing the air-mediated oxidation of thiol to disulfide form of glutathione. The co-elution of standard peptide and reaction mixture of oxidation of glutathione in presence of dimedone using RP-HPLC have confirmed the formation of glutathione cysteine sulfenic as an intermediate in the air-mediated oxidation of glutathione. The synthetic peptides of cysteine dimedone may find application in the field of redox proteomics and generation of antibodies against modified cysteine residue. 相似文献
10.
Isolation of a Neutral Boron‐Containing Radical Stabilized by a Cyclic (Alkyl)(Amino)Carbene 下载免费PDF全文
Dr. Philipp Bissinger Prof. Dr. Holger Braunschweig Dr. Alexander Damme Dr. Ivo Krummenacher Dr. Ashwini K. Phukan Dr. Krzysztof Radacki Shun Sugawara 《Angewandte Chemie (International ed. in English)》2014,53(28):7360-7363
Utilizing a cyclic (alkyl)(amino)carbene (CAAC) as a ligand, neutral CAAC‐stabilized radicals containing a boryl functionality could be prepared by reduction of the corresponding haloborane adducts. The radical species with a duryl substituent was fully characterized by single‐crystal X‐ray structural analysis, EPR spectroscopy, and DFT calculations. Compared to known neutral boryl radicals, the isolated radical species showed larger spin density on the boron atom. Furthermore, the compound that was isolated is extraordinarily stable to high temperatures under inert conditions, both in solution and in the solid state. Electrochemical investigations of the radical suggest the possibility to generate a stable formal boryl anion species. 相似文献