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101.
Reduction and subsequent aggregation of silver ions in the presence of various chelating agents such as trans-1,2-diaminocyclohexanetetraacetic acid (DCTA) 1,2-propylenediaminetetraacetic acid (PDTA), diethylenetriaminepentaacetic acid (DTPA), and triethylenetetraaminehexaacetic acid (TTHA) have been studied by pulse radiolysis. Rate constants of formation and transient absorption spectra for the ligand-complexed Ag(0) and Ag(2)(+) have been determined. The redox potential of Ag(+)(L)/Ag(0)(L) becomes more negative than that of Ag(+)/Ag(0). Growth and reactivity of silver clusters were also studied in the presence of methyl viologen (MV(2+)). The kinetics of formation of the MV(+*) radical, produced by the same pulse as in the case of silver atoms, confirms the catalytic electron transfer toward super critical silver clusters in the presence of ligands. The results suggest that catalytic electron transfer activity of silver clusters depends on the ligand. 相似文献
102.
By the use of time domain reflectometry method, dielectric measurements were carried out on dimethylformamide‐2‐nitrotoluene solvent mixtures in the frequency range 10 MHz‐20 GHz, at various temperatures from 15 °C to 45 °C. These solvent mixtures as well as pure solvents display a Debye type dispersion. Their frequency dependent dielectric properties can be summarized by the three parameters in the Debye equation: a static permittivity, permittivity at high frequency and a dielectric relaxation time constant. The free energy of activation for dipolar relaxation process and the Kirkwood correlation factor were determined using these fitting parameters for these solvent mixtures at various concentrations and temperatures. By using these dielectric parameters, the excess permittivity and excess inverse relaxation time is obtained. The excess permittivity is found to be positive for all concentrations and temperatures whereas the excess inverse relaxation time is negative. 相似文献
103.
Low molecular weight poly(dimethylsiloxane) and poly(methylphenylsiloxane) were synthesized and blended with polyimide (PI) at its precursor poly(amic acid) stage. FTIR analysis has proven the retention of polysiloxanes in polyimide after the ultimate curing of blends. Differential scanning calorimetric analysis was performed on polysiloxanes to elucidate the structures present in polymers while thermogravimetric analysis (TGA) was performed on polysiloxanes, polyimide as well as their blends to evaluate the thermal stability and to analyze the effect of polysiloxane incorporation in blends. Blends have shown synergistic improvement as compared to neat polyimide. 相似文献
104.
Ajay K. Bose Subhendu N. Ganguly Maghar S. Manhas Vaidyanathan Srirajan Ashoke Bhattacharjee Sochanchingwung Rumthao Anju H. Sharma 《Tetrahedron letters》2004,45(6):1179-1181
A novel dinitro secondary metabolite, 2-nitro-4-(2′-nitroethenyl)phenol from a marine source, has been prepared via highly accelerated, microwave assisted, nitration reactions using mild reagents. ipso-Substitution of a carboxy group by a nitro group is discussed. 相似文献
105.
Grindstone Chemistry--a greatly evolved version of Toda’s method of grinding solids together for solvent-free chemical reactions--has been described and its usefulness illustrated by the successful application of this technique to a simplified process for conducting the multi-component Biginelli reaction for the synthesis of physiologically active tetrahydropyrimidinones. 相似文献
106.
Microwave-induced organic reaction enhancement (‘MORE’) chemistry technique (open vessel; controlled microwave energy to stay below the boiling point of the reaction mixture) was used for the N-formylation of aliphatic and aromatic amines and amino heterocycles with aq formic acid (80%) on a multiple gram scale in a few minutes. 相似文献
107.
A greener and efficient method for the synthesis of ynones and 1,3-diynes using copper oxide nanoparticles (CuONPs) doped reduced graphene oxide (CuO@rGO) catalyst under palladium, ligand and solvent free conditions have been developed. The catalyst was subsequently utilized for the synthesis of biologically active 1,5-benzodiazepines in one pot via sequential addition of acyl chlorides, terminal alkynes and o-phenylenediamines. The methodology initially involves in situ formation of ynones which react with o-phenylenediamines in presence of ethanol to afford a wide variety of benzodiazepines. Mild reaction conditions, good to an excellent yield of the products, cheap and recyclable catalyst make this methodology environmentally benign and sustainable. 相似文献
108.
Mahendra Patel Haamid Haroon Ajay Kumar Jahangir Ahmad Gulzar A. Bhat Dr. Saifullah Lone Dhanya Putthusseri Prof. Kowsar Majid Dr. Malik Wahid 《Chemphyschem》2020,21(8):814-820
We chose to understand the cyclic instability and rate instability issues in the promising class of Na+ conversion and alloying anodes with Sb2Se3 as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb2Se3 material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g−1 at a specific current of 100 mA g−1 and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag−1 intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb2Se3-rGO) compared to bare Sb2Se3. GITT analysis reveals higher Na+ diffusion coefficients (approx. 30 fold higher) in the case of Sb2Se3-rGO as compared to bare Sb2Se3 throughout the operating voltage window. For Sb2Se3-rGO the diffusion coefficients in the range of 8.0×10−15 cm2 s−1 to 2.2×10−12 cm2 s−1 were observed, while in case of bare Sb2Se3 the diffusion coefficients in the range of 1.6×10−15 cm2 s−1 to 9.4×10−15 cm2 s−1 were observed. 相似文献
109.
Ajay Gupta Fillip Kumar Sarkar Rajib Sarkar Ramen Jamatia Chang Yeon Lee Gajendra Gupta Amarta Kumar Pal 《应用有机金属化学》2020,34(9):e5782
Magnetically retrieval CuFe2O4@MIL-101(Cr) metal–organic framework was successfully prepared from easily available starting materials and characterized using various spectroscopic and analytical techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, vibrating sample magnetometer, and inductively coupled plasma optical emission spectroscopy. The catalyst was then used in the synthesis of benzodiazepines containing a triazole moiety in water. The advantages of this protocol include high yields, reusability of the catalyst, and gram-scale synthesis. 相似文献
110.
Shih PI Chiang CL Dixit AK Chen CK Yuan MC Lee RY Chen CT Diau EW Shu CF 《Organic letters》2006,8(13):2799-2802
[reaction: see text] A series of carbazole/fluorene (CBZm-Fn) hybrids were effectively synthesized through Friedel-Crafts-type substitution of the carbazole rings. These compounds were thermally and morphologically stable host materials for OLED applications. Efficient blue phosphorescent OLEDs were obtained when employing CBZ1-F2 as the host and FIrpic as the guest. 相似文献