排序方式: 共有23条查询结果,搜索用时 31 毫秒
1.
Irem Dashan Melisa Elverici Demet Karaca Balta Binnur Aydogan Temel Gokhan Temel 《Journal of polymer science. Part A, Polymer chemistry》2019,57(12):1275-1282
Light‐responsive crosslinked structures were prepared by a straightforward quaternization strategy using chloride functional polystyrene copolymers and commercially available Michler's ketone with varying feed ratios. Resulting organogels demonstrated excellent solvent absorption and their swelling characteristics were altered by UV‐light irradiation. According to scanning electron microscope images, UV‐illuminated samples showed an obvious photodecomposition, which enhanced their solvent uptake capacity with increase of UV exposure. Additionally, release behavior of eosin Y as a model compound was determined by UV–vis and fluorescence spectrometers. Achieved photoactive gels were also employed as the reusable heterogeneous initiators for photoinduced free‐radical polymerization of methyl methacrylate. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1275–1282 相似文献
2.
Feng Li Melisa Rodas Ceballos Sepideh Keshan Balavandy Jingxi Fan Mohammad Mahdi Khataei Yadollah Yamini Fernando Maya 《Journal of separation science》2020,43(9-10):1854-1866
In the last 5 years, additive manufacturing (three‐dimensional printing) has emerged as a highly valuable technology to advance the field of analytical sample preparation. Three‐dimensional printing enabled the cost‐effective and rapid fabrication of devices for sample preparation, especially in flow‐based mode, opening new possibilities for the development of automated analytical methods. Recent advances involve membrane‐based three‐dimensional printed separation devices fabricated by print‐pause‐print and multi‐material three‐dimensional printing, or improved three‐dimensional printed holders for solid‐phase extraction containing sorbent bead packings, extraction disks, fibers, and magnetic particles. Other recent developments rely on the direct three‐dimensional printing of extraction sorbents, the functionalization of commercial three‐dimensional printable resins, or the coating of three‐dimensional printed devices with functional micro/nanomaterials. In addition, improved devices for liquid–liquid extraction such as extraction chambers, or phase separators are opening new possibilities for analytical method development combined with high‐performance liquid chromatography. The present review outlines the current state‐of‐the‐art of three‐dimensional printing in analytical sample preparation. 相似文献
3.
Luo Z Oki A Carson L Adams L Neelgund G Soboyejo N Regisford G Stewart M Hibbert K Beharie G Kelly-Brown C Traisawatwong P 《Chemical physics letters》2011,513(1-3):88-93
The thermal stability of funtionalized carbon nanotubes (CNTs) has been studied experimentally by direct in-situ observations using a heating stage in a transmission electron microscope, from room temperature (RT) to about 1000 °C. It was found that the thermal stability of the functionalized CNTs was significantly reduced during the in-situ heating process. Their average diameter dramatically expanded from RT to about 500 °C, and then tended to be stable until about 1000 °C. The X-ray energy dispersive spectroscopy analysis suggested that the diameter expansion was associated with coalescence of the carbon structure instead of deposition with additional foreign elements during the heating process. 相似文献
4.
Alejandro De Falco Mirta L. Fascio Melisa E. Lamanna Maria A. Corcuera Iaki Mondragon Gerardo H. Rubiolo Norma B. DAccorso Silvia Goyanes 《Physica B: Condensed Matter》2009,404(18):2780-2783
In this work we studied the functionalization of commercially available multiwalled carbon nanotubes (MWCNT) (Nanocyl 3100) with polystyrene by the method so called “grafting from”. The nanotubes were used as received and oxidized in air at 400 °C. The functionalization was started using thionyl chloride under reflux, followed by a reaction with ethylene glycol which allowed the inclusion of hydroxyl groups. The reaction of those with 2-chloropropionyl chloride led to the generation of the polymerization initiator. Last, the radical polymerization of the functionalized nanotubes, using styrene as the monomer, led to new materials which were studied with thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and ultraviolet–visible (UV–vis) spectroscopy. 相似文献
5.
Dr. Haixiang Han Jesse C. Carozza Audra P. Colliton Yuxuan Zhang Dr. Zheng Wei Dr. Alexander S. Filatov Prof. Dr. Yu-Sheng Chen Melisa Alkan Prof. Dr. Andrey Yu. Rogachev Prof. Dr. Evgeny V. Dikarev 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9711-9717
A known trinuclear structure was used to design the heterobimetallic mixed-valent, mixed-ligand molecule [CoII(hfac)3−Na−CoIII(acac)3] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [CoII(hfac)3−Na−FeIII(acac)3] ( 2 ) and [NiII(hfac)3−Na−CoIII(acac)3] ( 3 ) via isovalent site-specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple-wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di- and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O4 functional oxide materials. 相似文献
6.
Prof. Dr. Andrey Yu. Rogachev Melisa Alkan Dr. Jingbai Li Shuyang Liu Dr. Sarah N. Spisak Dr. Alexander S. Filatov Prof. Dr. Marina A. Petrukhina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(62):14140-14147
One-electron reduction of corannulene, C20H10, with Li metal in diglyme resulted in crystallization of [{Li+(diglyme)2}4(C20H10.−)2(C20H10-C20H10)2−] ( 1 ), as revealed by single-crystal X-ray diffraction. This hybrid product contains two corannulene monoanion-radicals along with a dianionic dimer, crystallized with four Li+ ions wrapped by diglyme molecules. The dimeric (C20H10-C20H10)2− anion provides the first crystallographically confirmed example of spontaneous radical dimerization for C20H10.−. The C−C bond length between the two C20H10.− bowls of 1.588(5) Å is consistent with the single σ-bond character of the linker. The trans-disposition of two bowls in the centrosymmetric (C20H10-C20H10)2− dimer is observed with the torsion angle around the central C−C bond of 180°. Comprehensive theoretical analysis of formation/decomposition processes of the dimeric dianion has been carried out in order to evaluate the nature of bonding and energetics of the C20H10.− coupling. It is found that such σ-bonded dimers are thermodynamically unstable due to large preparation energy and repulsive Pauli component of the bonding, but kinetically persistent due to a high energy barrier provided by the existing spin-crossing point. 相似文献
7.
8.
9.
Site‐Directed Dimerization of Bowl‐Shaped Radical Anions to Form a σ‐Bonded Dibenzocorannulene Dimer
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Sarah N. Spisak Dr. Alexander V. Zabula Melisa Alkan Dr. Alexander S. Filatov Prof. Dr. Andrey Yu. Rogachev Prof. Dr. Marina A. Petrukhina 《Angewandte Chemie (International ed. in English)》2018,57(21):6171-6175
Designed site‐directed dimerization of the monoanion radicals of a π‐bowl in the solid state is reported. Dibenzo[a,g]corannulene (C28H14) was selected based on the asymmetry of the charge/spin localization in the C28H14.? anion. Controlled one‐electron reduction of C28H14 with Cs metal in diglyme resulted in crystallization of a new dimer, [{Cs+(diglyme)}2(C28H14?C28H14)2?] ( 1 ), as revealed by single crystal X‐ray diffraction study performed in a broad range of temperatures. The C?C bond length between two C28H14.? bowls (1.560(8) Å) measured at ?143 °C does not significantly change upon heating of the crystal to +67 °C. The single σ‐bond character of the C?C linker is confirmed by calculations. The trans‐disposition of two bowls in 1 is observed with the torsion angles around the central C?C bond of 172.3(5)° and 173.5(5)°. A systematic theoretical evaluation of dimerization pathways of C28H14.? radicals confirmed that the trans‐isomer found in 1 is energetically favored. 相似文献
10.
One of the challenges in metabolomic profiling of complex biological samples is to identify new and unknown compounds. Typically, standards are used to help identify metabolites, yet standards cannot be purchased or readily synthesized for many unknowns. In this work we present a strategy of using human liver microsomes (HLM) to metabolize known endogenous human metabolites (substrates), producing potentially new metabolites that have yet to be documented. The metabolites produced by HLM can be tentatively identified based on the associated substrate structure, known metabolic processes, tandem mass spectrometry (MS/MS) fragmentation patterns and, if necessary, accurate mass measurements. Once identified, these metabolites can be used as references for identification of the same compounds in complex biological samples. As a proof of principle, a total of 9 metabolites have been identified from individual HLM incubations using 5 different substrates. Each metabolite was used as a standard. In the analysis of human urine sample by liquid chromatography MS/MS, four spectral matches were found from the 9 microsome-produced metabolite standards. Two of them have previously been documented as endogenous human metabolites, the third is an isomer of a microsome-metabolite and the fourth compound has not been previously reported and is also an isomer of a microsome-metabolite. This work illustrates the feasibility of using microsome-based metabolism to produce metabolites of endogenous human metabolites that can be used to facilitate the identification of unknowns in biological samples. Future work on improving the performance of this strategy is also discussed. 相似文献