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41.
Dr. Dongpeng Yan Dr. Dejan‐Krešimir Bučar Dr. Amit Delori Bhavnita Patel Dr. Gareth O. Lloyd Prof. William Jones Prof. Xue Duan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(25):8213-8219
Multi‐component organic nanocrystals that are comprised of two or more supramolecular building blocks can be used to extend the design and assembly scope of solid molecular materials. Herein, we report the use of ultrasonication to prepare halogen‐bonded stilbene‐based nano‐cocrystals that exhibit different photoemission properties, including one‐ and two‐phonon emission and fluorescence lifetimes, relative to those of macrodimensional crystals. The structural transformation from nano‐cocrystals into nanocrystals upon heating results in a luminescence red‐shift from greenish blue to yellow. The temperature‐dependent ratiometric luminescence may allow such nano‐cocrystals to be used as fluorescent sensors and thermosensitive materials. 相似文献
42.
A mathematical theory of time-dependent dislocation mechanics of
unrestricted geometric and material nonlinearity is reviewed. Within
a ``small deformation" setting, a suite of simplified and
interesting models consisting of a nonlocal Ginzburg Landau
equation, a nonlocal level set equation, and a nonlocal generalized
Burgers equation is derived. In the finite deformation setting, it
is shown that an additive decomposition of the total velocity
gradient into elastic and plastic parts emerges naturally from a
micromechanical starting point that involves no notion of plastic
deformation but only the elastic distortion, material velocity,
dislocation density and the dislocation velocity. Moreover, a
plastic spin tensor emerges naturally as well. 相似文献
43.
A simple and convenient approach for the synthesis of unsymmetrical diaryl chalcogenides (Te, Se, and S) has been developed by copper-catalyzed cross-coupling reaction of organoboronic acid with diaryl dichalcogenide in ethanol using NaBH4 in air or oxygen. The present methodology is highly practical for the synthesis of unsymmetrical diaryl tellurides with various functionalities such as –NO2, –F, –Br, and –COOH that have been obtained in good to excellent yields. Methodology is also effective for the synthesis of unsymmetrical diaryl selenides and sulfides. Moreover, symmetrical diaryl selenides have also been obtained from arylboronic acids using elemental selenium powder under optimized reaction conditions. The use of NaBH4 is the key for the development of milder reaction conditions, which enable the construction of unsymmetrical diaryl chalcogenides from boronic acid substrates in ethanol at room temperature. 相似文献
44.
A facile, single pot diastereoselective access to seven and eight membered aza-heterocycles was developed by using β-lactam-synthon approach. The developed protocol does not involve the typical intricacies viz. the use of expensive transition metal catalysts and high boiling solvents, associated with the convenient protocols. 相似文献
45.
Nitro‐Substituted Bishomocubanes: Synthesis,Characterization, and Application as Energetic Materials 下载免费PDF全文
Sohan Lal Dr. Sundaram Rajkumar Amit Tare Dr. Sasidharakurup Reshmi Prof. Dr. Arindrajit Chowdhury Prof. Dr. Irishi N. N. Namboothiri 《化学:亚洲杂志》2014,9(12):3533-3541
Several high‐energy‐density strained polycyclic compounds nitromethyl‐l,3‐bishomocubane (NMBHC), nitromethylene‐1,3‐bishomocubane (NMyBHC), and bis(nitromethyl)‐1,3‐bishomocubane (DNTMBHC), which were synthesized for the first time from bishomocubanone, hold potential for application as standalone fuels in liquid bipropellant systems or as additives in liquid and solid propellant formulations. DFT analysis at the B3LYP/6‐31G(d) level of theory was employed to optimize the geometries of the compounds and to determine their densities, heats of formation, and various thermodynamic properties. The density specific impulse, determined by using equilibrium thermodynamics, demonstrated an improvement of 75 s for NMBHC and NMyBHC over standard hydrocarbons. The specific impulse with ammonium perchlorate showed an improvement of 25–30 s over hydroxy‐terminated polybutadiene. Thermogravimetric analysis revealed that NMBHC, NMyBHC, and DNTMBHC evaporated readily with activation energies of 58.8, 69.2, and 74.5 kJ mol?1, respectively. 相似文献
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48.
Thomas H. Walter Bonnie A. Alden Kenneth Berthelette Jessica A. Field Nicole L. Lawrence Justin McLaughlin Amit V. Patel 《Journal of separation science》2022,45(8):1389-1399
We have characterized a sulfobetaine stationary phase based on 1.7 μm ethylene-bridged hybrid organic–inorganic particles, which is intended for use in hydrophilic interaction chromatography. The efficiency of a column packed with this material was determined as a function of flow rate, demonstrating a minimum reduced plate height of 2.4. The batch-to-batch reproducibility was assessed using the separation of a mixture of acids, bases, and neutrals. We compared the retention and selectivity of the hybrid sulfobetaine stationary phase to that of several benchmark materials. The hybrid sulfobetaine material gave strong retention for polar neutrals and high selectivity for methyl groups, hydroxy groups, and configurational isomers. Large differences in cation and anion retention were observed among the columns. We characterized the acid and base stability of the hybrid sulfobetaine stationary phase, using accelerated tests at pH 1.3 and 11.0, both at 70°C. The results support a recommended pH range of 2–10. We also investigated the performance of columns packed with this material for metal-sensitive analytes, comparing conventional stainless steel column hardware to hardware that incorporates hybrid surface technology to mitigate interactions with metal surfaces. Compared to the conventional columns, the hybrid surface technology columns showed a greatly improved peak shape. 相似文献
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50.
Amit S. Nagare Arpan Manna Pramod D. Sonawane Anil Kumar 《Journal of Physical Organic Chemistry》2015,28(11):665-673
Prevailing classification of salts based on their effect in solubility and stability of proteins in aqueous solution predicts that tetraalkylammonium salts, guanidinium chloride (GnCl), LiClO4 act as salting‐in (S/I) and LiCl, NaCl act as salting‐out (S/O) in aqueous conditions. In the same context the behaviour of GnCl, LiClO4 and LiCl are contradictory in polar solvents like ethylene glycol and formamide. In these solvents, expected salt effect shows just opposite nature from their usual expectation. However, in the aqueous solution salts like tetraalkylammonium halide (R4NX, R = alkyl group, X = Br group) behave like salting‐in salts. The physicochemical origin of the salting in effect of R4NX type of salts has been discussed elaborately in the present work. The role of cations in terms of substitution of various alkyl groups on R4NX has been systematically presented here on the basis of experimental kinetic and thermodynamic studies. The abnormal behaviour of R4NX salts in aqueous solution has also been explained by the Setschenov equation (ks) and Δμsolvation values, which highlights their individual nature out of common properties of R4NX. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献