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排序方式: 共有263条查询结果,搜索用时 281 毫秒
1.
Ajit Kumar Singh Seulgi Ji Baghendra Singh Chittaranjan Das Heechae Choi Prashanth W. Menezes Arindam Indra 《Materials Today Chemistry》2022
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport. 相似文献
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Indra K. Varma George M. Fohlen John A. Parker 《Journal of polymer science. Part A, Polymer chemistry》1982,20(2):283-297
Ten structurally different bisimide resins were prepared by reacting maleic anhydride/citraconic anhydride and benzophenone tetracarboxylic dianhydride with aromatic diamines and fused aromatic structures or heterocyclic groups. The amines included were 1,5-diaminonaphthalene, 2,5-bis(p-aminophenyl)1,3,4-oxadiazole, 3,3-bis(p-aminophenyl)phthalide, 9,9-bis(p-aminophenyl)fluorene. and 10,10-bis(p-aminophenyl)anthrone. These monomers were characterized by infrared (IR). 1H-NMR, mass spectroscopy, and elemental analysis. Thermal polymerization of these monomers was investigated by differential scanning calorimetry. Broad exothermic peaks were observed for a temperature range of 225–380°C. Temperature of exothermic peak position was influenced by the presence of substituents at the olefinic bond, and in biscitraconimides it was 40–50°C lower than in the corresponding bismaleimides. Anaerobic char yields of cured bisimide resins ranged from 44 to 64%. Oxadiazole-containing bisimides had low thermal stability. Increase in formula weight between the imide groups did not influence the char yields in a systematic manner. Graphite cloth laminates with two of these bisimide resins were fabricated and tested for a number of physical properties. Their limiting oxygen index was 70–72%. 相似文献
4.
Kritika Keshari Moumita Bera Lucía Velasco Sandip Munshi Geetika Gupta Dooshaye Moonshiram Sayantan Paria 《Chemical science》2021,12(12):4418
A terminal FeIIIOH complex, [FeIII(L)(OH)]2− (1), has been synthesized and structurally characterized (H4L = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene). The oxidation reaction of 1 with one equiv. of tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBAH) or ceric ammonium nitrate (CAN) in acetonitrile at −45 °C results in the formation of a FeIIIOH ligand radical complex, [FeIII(L˙)(OH)]− (2), which is hereby characterized by UV-visible, 1H nuclear magnetic resonance, electron paramagnetic resonance, and X-ray absorption spectroscopy techniques. The reaction of 2 with a triphenylcarbon radical further gives triphenylmethanol and mimics the so-called oxygen rebound step of Cpd II of cytochrome P450. Furthermore, the reaction of 2 was explored with different 4-substituted-2,6-di-tert-butylphenols. Based on kinetic analysis, a hydrogen atom transfer (HAT) mechanism has been established. A pKa value of 19.3 and a BDFE value of 78.2 kcal/mol have been estimated for complex 2.One-electron oxidation of an FeIII–OH complex (1) results in the formation of a FeIII–OH ligand radical complex (2). Its reaction with (C6H5)3C˙ results in the formation of (C6H5)3COH, which is a functional mimic of compound II of cytochrome P450. 相似文献
5.
Vidya Rani Chandrasekhar Kesavan Mookkandi Palsamy Ravi Lokesh Daniel Thangadurai T. Indra Gandhi N. Rajesh Jegathalaprathaban Rajagopal Gurusamy 《应用有机金属化学》2019,33(3)
Three new metal complexes [Cu(L)2] (1), [Co(L)2] (2) and [Zn(L)2] (3) have been prepared by the reaction of hydrated salts of metal (II) acetate with new Schiff base ligand HL, [2‐((4‐(dimethylamino)phenylimino)methyl)‐4,6‐di‐t‐butylphenol] and characterized by different physico‐chemical analyses such as elemental analysis, single XRD, 1H NMR, FTIR and UV–Vis spectroscopic techniques. Their biomolecular docking, antimicrobial and cytotoxicity studies have also been demonstrated. The proposed structure of Schiff base ligand HL and complex 2 are confirmed by Single crystal X‐ray crystallography study. This analysis revealed that metal (II) complexes remain in distorted tetrahedral coordination environments. The electronic properties such as HOMO and LUMO energies are carried out by gaseous phase DFT/B3LYP calculations using Gaussian 09 program. Complex 1 showed a good binding propensity to the DNA and HSA, during the assessment of docking studies. Schiff base ligand HL and its metal (II) complexes, 1–3 screened for their in vitro antimicrobial activities using the disc diffusion method against selected microbes. Complex 1 shows higher antimicrobial activity than complexes 2, 3 and Schiff base ligand HL. According to the results obtained from the cytotoxic studies, Schiff base ligand HL and its metal (II) complexes 1–3 have better cytotoxicity against MCF‐7 cell lines with potency higher than the currently used chemotherapeutic agent cyclophosphamide. 相似文献
6.
Sini Nalakathu Kolanadiyil Jayashree Bijwe Indra K. Varma 《Journal of Thermal Analysis and Calorimetry》2014,116(1):427-434
Blends of cardanol-based bisbenzoxazine (BZc) and 4,4′-bisitaconimidodiphenyl ether (BIM) having nine different mass ratios (i.e. 100:0, 90:10, 75:25, 60:40, 50:50, 40:60, 25:75, 10:90 and 0:100) were prepared and their curing behaviour was studied by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy. A curing mechanism comprising two-steps: (1) homopolymerization and co-curing reaction of itaconimide with alkyl side chain double bonds of cardanol BZc at lower temperature (~443 K) and (2) ring-opening polymerization of oxazine at higher temperature (~453–483 K) has been proposed. The T g of the cured resin blends was determined by DSC and the increase in BIM content in the blend resulted in an increase in T g from 408 K BZc to 474 K BIM. Increase in bisitaconimide content resulted in improvement of char yield at 1,073 K as well as an increase in mass loss temperatures (5 and 10 %). Compared to BZc, the blends showed a higher thermal stability. The lap shear strength of these blends in metal–metal joints was investigated at 323, 523 and 573 K. 相似文献
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Side chain bromination of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was carried out by using N-bromosuccinimide followed by phosphorylation of the bromo derivative with triethyl phosphite. Optimum conditions for minimum gel formation have been established. The products have been characterized by 'H-NMR and IR studies. Thermal behavior was investigated by thermogravimetry and differential scanning calorimetry in an air nitrogen atmosphere. Phosphorylated PPO starts to lose weight at 200°C, but the char yield increases with an increase in the phosphorus content of the polymer. 相似文献
9.
Mechanical properties of copolymers of 2-hydroxyethyl methacrylate with methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate have been investigated using an Instron tensile tester. It was observed that the overall mechanical properties decrease as the ester alkyl group of alkyl methacrylate becomes bulkier. Biocompatibility of the copolymers was also investigated by implanting them subcutaneously in rats. 相似文献
10.
Bimlesh Lochab Indra K. Varma Jayashree Bijwe 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1357-1364
This article describes synthesis, characterization and properties of blends of benzoxazine (Bz) monomers, i.e., m-alkylphenyl-3,4-dihydro-2H-benzoxazine (Bz-C), 6,6′-(propane-2,2-diyl)bis(3-phenyl-3,4-dihydro-2H-benzoxazine (Bz-A) and 3-phenyl-3,4-dihydro-2H-benzoxazine-p-carboxylic acid (Bz-pA). Binary blends of Bz-C with Bz-pA, and Bz-A with Bz-pA were prepared by first synthesizing Bz-C or Bz-A followed by the addition of all the ingredients of Bz-pA. In a similar manner, ternary blends of Bz-C, Bz-A and Bz-pA were prepared by first synthesizing Bz-C and subsequent addition of all the ingredients of Bz-A and Bz-pA in one pot. The Bz monomer blends were characterized by 1H-NMR, FTIR spectroscopy, and differential scanning calorimetry. The temperature of onset of curing (T o), due to ring-opening polymerization of Bz was found to decrease significantly by incorporation of carboxyl groups (Bz-pA) showing thereby the catalytic effect of acid functionality. Bz polymers showed good thermal stability and incorporation of Bz-pA in blends resulted in a highly cross-linked network. The interlaminar shear strength of glass fabric reinforced composites and the lap shear strength of metal–metal joints using these resin blends was also investigated. 相似文献