Results 1 - 10 of 244
Results 1 - 10 of 244. Search took: 0.018 seconds
|Sort by: date | relevance|
[en] We describe the development of a density-dependent transferable coarse-grain model of crystalline hexahydro-1,3,5-trinitro-s-triazine (RDX) that can be used with the energy conserving dissipative particle dynamics method. The model is an extension of a recently reported one-site model of RDX that was developed by using a force-matching method. The density-dependent forces in that original model are provided through an interpolation scheme that poorly conserves energy. The development of the new model presented in this work first involved a multi-objective procedure to improve the structural and thermodynamic properties of the previous model, followed by the inclusion of the density dependency via a conservative form of the force field that conserves energy. The new model accurately predicts the density, structure, pressure-volume isotherm, bulk modulus, and elastic constants of the RDX crystal at ambient pressure and exhibits transferability to a liquid phase at melt conditions.
[en] Heating the substituted pyridinium and isoquinolinium salts with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes in either chloroform or acetone in the presence of three-fold excess of Et3N gave high yields of substituted 1,2-di(alkylsulfonyl)indolizines and 1,2-di(alkylsulfonyl) pyrrolo[2,1-a]isoquinolines, respectively. Effects of the structure of 3-substituted pyridinium ylides on the regioselectivity of their reaction with E-1,2-di(alkylsulfonyl)-1,2-dichloroethenes were revealed. It was shown that the presence of electron-releasing and electron-withdrawing substituents in the pyridinium ylide favors the formation of 8-substituted and 6-substituted 1,2-(dialkylsulfonyl)indolizines, respectively.
[en] In this study, octacationic and nonanuclear supramolecular porphyrazines were synthesized and characterized by the common spectral methods. For the synthesis of target octacationic and supramolecular structures, first the octakis(2-hydroxyethylthio) porhyrazinatomagnesium (MgOHPz) which was required for the designing of the core of the supramolecule, was synthesized as given in the literature. The second step of the supramolecular structure was the addition of pyridyl donors on the periferal positions of the porphrazineunit. For this purpose, MgOHPz was reacted with pyridine-4-carboxylic acid to give the ester units on the periferies of porphyrazine. Octakis(4-pyridoxyethylthio) porphyrazinato magnesium(MgPyPz) was prepared by the complete esterification of all the OH-groups in MgOHPz with pyridine-4-carboxylic acid (isonicotinic acid) in pyridine by the presence of dicyclohexylcarbodiimide and 4-toluenesulphonic acid as catalysts in seven days at ambient temperature. The blue-green color octakis(4-pyridoxyethylthio) porphyrazinatomagnesium, MgPyPz, was isolated with good yield. The octacationic molecule was obtained after the quaternization of the MgPyPz with iodomethane in the dark. The ready solubility of the product in water confirms the proposed structure. The nonanuclear supramolecule was prepared by the coordination reaction of the vanadylacetylacetonate, VO(acac)2 with MgPyPz and characterized by EPR technique together with the spectral data
[en] The review surveys synthetic approaches to spiro[1,4]oxazines belonging to one of the most promising classes of organic photochromes. The relationships between the structures of spirooxazines and their spectral properties as well as characteristics of thermal and photoinduced processes are considered. The bibliography includes 201 references.
[en] This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. For this purpose, a series of halogenated salicylaldehyde azine derivatives, namely, chloro-salicylaldehyde azine (1), bromo-salicylaldehyde azine (2) and iodo-salicylaldehyde azine (3) are synthesized. 1 and 2 display typical AIEE characteristics of salicylaldehyde azine compounds; whereas for the iodo-substituent in 3, is found to be effective “external” heavy atom quenchers to salicylaldehyde azine fluorescence in aggregated state. Based on its weak fluorescence in aggregated state and relative strong fluorescence in dispersed state, 3 can also be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction. -- Highlights: • This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. • Chloro- and bromo-salicylaldehyde display typical AIEE properties of salicylaldehyde azine, whereas the iodo-substitute quenches AIEE in aggregated state. • Iodo-salicylaldehyde can be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction
[en] A methoxyphenylcycl[3,2,2]azine derivative (MPC) was synthesized and its function as a fluorescent probe for metal ions was investigated. Studies revealed that the fluorescence intensity of cycl[3.2.2]azine derivative varies with the concentration of Co2+ ion. The sensor was highly selective towards Co2+ ion over other metal ions and was found to be sensitive towards Co2+ ion with a detection limit of 2.85×10−3 M. A linear concentration range from 2.30×10−2 M to 4.76×10−3 M was obtained. Furthermore the sensor could be utilized for the determination of Co2+ in pharmaceutical samples.
[en] Prospects of the method of complete refining by complexing via monoazines is demonstrated at examples of production of superpure tellurium out of Te-Al, engineering grade and of indium out of TsMTU 1783-56, and semiconducting indium phosphide at 20-150 deg C out of industrial indium. Purification technique is described and results of purification efficiency analysis are presented