排序方式: 共有85条查询结果,搜索用时 0 毫秒
51.
52.
Zahra Amouzegar Abbas Afkhami Tayebeh Madrakian 《Journal of the Iranian Chemical Society》2017,14(12):2475-2483
The interaction between water-soluble zinc sulfide quantum dots (ZnS QDs) and selenite ion was investigated by photoluminescence method. The water-soluble ZnS QDs were synthesized using a simple and fast procedure based on the co-precipitation of nanoparticles in an aqueous solution in the presence of 3-mercaptopropionic acid (MPA), as the capping agent. Fluorescence intensity for MPA–ZnS QDs, with a strong fluorescent emission at about 430 nm, decreased in the presence of selenite. The influence of the effective parameters including pH and temperature was investigated. The results showed that under the optimum conditions, the fluorescence intensity change of QDs was linearly proportional to the selenite concentration in the range 4.0 × 10?5–7.2 × 10?4 mol L?1. Moreover, the quenching mechanism was discussed to be a static quenching procedure. 相似文献
53.
Mobina Ahmadi Tayebeh Behzad Rouhollah Bagheri Mehran Ghiaci Mohini Sain 《Cellulose (London, England)》2017,24(5):2139-2152
The aim of this study was to synthesize hydrophobic cellulose nanofibers (CNFs) using different chemical treatments including polymer and molecular grafting. For polymer grafting, immobilizing poly (butyl acrylate) (PBA) and poly (methyl methacrylate) (PMMA) on CNFs were implemented by the free radical method. Also, acetyl groups were introduced directly onto the CNFs surface by acetic anhydride for molecular grafting. The gravimetric and X-ray photoelectron spectroscopy analysis showed the high grafting density of PMMA on the surface of CNFs. AFM results revealed that molecular grafting created non-uniformity on the CNFs surface, as compared to polymer brushes. In addition, thermodynamic work of adhesion and work of cohesion for the modified CNFs were reduced in water and diiodomethane solvents. Dispersion factor was studied to indicate the dispersibility of CNFs in polar and non-polar media. Dispersion energy was reduced after modification as a result of decreasing interfacial tension and the dispersibility of modified CNFs was improved in diiodomethane. 相似文献
54.
Vahideh Zadsirjan Majid M. Heravi Mahmoud Tajbakhsh Hossein A. Oskooie Morteza Shiri Tayebeh Hosseinnejad 《Research on Chemical Intermediates》2016,42(7):6407-6422
Hydroarylation of cinnamic acid with different substituted phenols, in the presence of acidic ionic liquid, N-methyl-2-pyrrolidonum hydrosulfate ([H-NMP]HSO4) gave the corresponding dihydrocoumarins in high yields and excellent selectivity. Among these substituted phenols, while methyl phenol afforded the corresponding dihydrocoumarin, nitrophenol under the same reaction conditions diverted the course of reaction, affording 3-(4-nitrophenyl)-3-phenylpropanoic acids. We investigated this behavior from the energetic and electronic points of view, using quantum chemistry computational methods. In this respect, the electronic energy change values for the conversion reaction of substituted phenyl cinnamate esters to dihydrocoumarin compounds have been obtained via density functional theory calculations. We demonstrated that the conversion reaction in the presence of CH3 substituent is more favorable energetically than NO2 substituent. Moreover, we have concentrated on topological analysis of electron density on some key bond and ring critical points and their associated bond paths to assess the conversion of substituted phenyl cinnamate esters to dihydrocoumarins. Our calculated results showed that para-methyl phenyl cinnamate has more of electronic tendency to undergo the intramolecular cyclization step and, consequently, generate the corresponding dihydrocoumarin. 相似文献
55.
56.
57.
In this research, a novel KIT-5/Bi2S3-Fe3O4 nanocomposite was prepared. The structure and morphology properties of the nanocomposite were well characterized by XRD, FESEM-EDS-mapping, TEM, and N2 adsorption–desorption. Benefiting from the visible light, the as-prepared KIT-5/Bi2S3-Fe3O4 nanocomposite exhibit significantly improved photocatalytic performance for the degradation of parathion. The optimum photocatalytic efficiency of KIT-5/Bi2S3-Fe3O4 nanocomposite was investigated with the central composite design using Design Expert software. The four critical variables affecting parathion degradation such as the concentration of parathion, pH, irradiation time, and amount of KIT-5/Bi2S3-Fe3O4 nanocatalyst. A polynomial function corresponding to degradation percent was obtained for the experimental data. The results showed that this catalyst has a good performance for the degradation of parathion. 相似文献
58.
59.
Zare Abdolkarim Ghobadpoor Aysoda Safdari Tayebeh 《Research on Chemical Intermediates》2020,46(2):1319-1327
Research on Chemical Intermediates - In this research, firstly, preparation and characterization of a novel dicationic molten salt, namely N,N,N′,N′-tetramethylethylenediaminium... 相似文献
60.
An efficient approach for the assembly of 1,4-diazepine-based and 6-(4-oxo-chromen-3-yl)-pyrazinone-based frameworks has been developed that involves the Ugi four-component reaction (U-4CR) followed by Staudinger/nucleophilic cyclization and Staudinger/Aza-Wittig reactions, respectively. This convergent approach exhibits a high bond-forming efficiency, involving the use of readily available commercial reagents and is an example of the reconciliation of structural complexity with operational simplicity in a time- and cost-effective manner. 相似文献