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61.
Antiaromatic molecules have been predicted to exhibit increased electron transport properties when placed between two nanoelectrodes compared to their aromatic analogues. While some studies have demonstrated this relationship, others have found no substantial increase. We use atomistic simulations to establish a general relationship between the electronic spectra of aromatic, antiaromatic, and quinoidal molecules and illustrate its implications for electron transport. We compare the electronic properties of a series of aromatic-antiaromatic counterparts and show that antiaromaticity effectively p-dopes the aromatic electronic spectra. As a consequence, the conducting properties of aromatic-antiaromatic analogues are closely related. For similar attachment points to the electrodes, an interference feature is expected in the HOMO-LUMO gap of one whenever it is absent in the other one. We demonstrate how the relative conductance of aromatic-antiaromatic pairs can be tuned and even reversed through the choice of chemical linker groups. Our work provides a general picture relating connectivity, (anti)aromaticity, and quantum interference and establishes new design rules for single molecule circuits. 相似文献
62.
Pristine palladium nanoparticles were decorated on graphene nanosheets for the development of a low-cost, nonenzymatic ethanol sensor. The nanocomposite was characterized by ultraviolet–visible absorbance spectroscopy, infrared spectroscopy, and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. Cyclic voltammetry and chronoamperometry were used to quantify ethanol in alkaline media. A graphene palladium nanocomposite-modified glassy carbon electrode provided a detection limit of 2?mM with a linear dynamic range of 2–210?mM for ethanol determination. The nanocomposite exhibited excellent stability for 100 cyclic voltammetry scans. Ethanol oxidation was performed across a range of temperatures, unlike enzymatic based sensors. Moreover, the catalytic material showed a low activation energy and low onset potentials for the oxidation of ethanol. Interference studies with congeners of ethanol in fermentation chambers showed good selectivity for the analyte. The enhanced catalytic activity for ethanol detection involves the combination of pristine palladium nanoparticles with the enhanced conductivity of graphene. 相似文献
63.
Pankaj Saraswat Govindasamy Jeyabalan Mohd. Zaheen Hassan Mujeeb U. Rahman Narendra K. Nyola 《合成通讯》2016,46(20):1643-1664
Spirocyclic compounds isolated from plant and animal origins have important applications in medicinal chemistry. Spiro compounds having cyclic structures fused at a central carbon are of recent interest because of their interesting conformational features and their structural implications for biological systems. Spiro heterocycles like spiropyrrolidines and oxindole moieties have been found to play fundamental roles in biological processes and have exhibited diversified biological activity and pharmacological and therapeutical properties. In view of these facts we decided to present a representative synthetic scheme and various biological activities of the heterocycles like spiropyrrolidines and oxindole moieties derivatives, especially in relation to microbial infections like cancer and tubercular, viral, HIV, bacterial, and fungal infections. 相似文献
64.
Dr. Alam Venugopal Narendra Kumar Yinghao Li Shuli Yin Chunjie Li Dr. Hairong Xue Dr. You Xu Prof. Xiaonian Li Dr. Hongjing Wang Prof. Liang Wang 《化学:亚洲杂志》2018,13(16):2093-2100
Tailoring metal oxide nanostructures with mesoporous architectures is vital to improve their electrocatalytic performance. Herein, we demonstrate the synthesis of 2D mesoporous Co3O4 (meso‐Co3O4) nanobundles with uniform shape and size by employing a hard‐template method. In this study, the incipient wetness impregnation technique has been chosen for loading metal precursor into the silica hard template (SBA‐15). The results reveal that the concentration of a saturated precursor solution plays a vital role in mesostructured ordering, as well as the size and shape of the final meso‐Co3O4 product. The optimized precursor concentration allows us to synthesize ordered meso‐Co3O4 with four to seven nanowires in each particle. The meso‐Co3O4 structure exhibits excellent electrocatalytic activity for both glucose and water oxidation reactions. 相似文献
65.
Narendra Pal Singh Chauhan Mazaher Gholipourmalekabadi Masoud Mozafari 《高分子科学杂志,A辑:纯化学与应用化学》2017,54(10):655-661
The combination of pectins and germanium dioxide may generate novel materials with excellent and unique properties combining the advantages of macromolecules, derived from renewable resources and metal oxide nanoparticles. Pectin–GeO2 nanocomposite was prepared by hydrothermal method at room temperature. Structural morphology and chemical interactions between GeO2 and pectin were analyzed using Fourier Transform Infrared Spectroscopy Equipped with Attenuated Total Reflectance (FTIR-ATR), AC impedance spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray Spectrophotometer (SEM-EDS) Thermo gravimetric analysis (TG) and Differential Scanning Calorimetry (DSC). According to the TEM observation, the average composite granules size was about 70 nm and the embedded GeO2 nanoparticles were uniform with an average diameter of 20 nm. The pectin-germanium dioxide degradation was observed in one single DSC endoderm peak at 100°C (Area swept 276.4 mJ and enthalpy change 48.1 J/g) and three DTG peaks in the temperature range between 165 and 570°C. All the results suggest the pectin–GeO2 nanocomposite as a promising candidate for biomedical and environmental applications. 相似文献
66.
Abhishek Upadhyay Vinay K. Singh Rahul Dubey Narendra Kumar L.K. Sharma Rana Krishna Pal Singh 《Tetrahedron letters》2017,58(46):4323-4327
A highly efficient one pot, multicomponent synthesis of 4H-benzo[g]chromene and pyrano[2,3-g]chromene derivatives are reported by electrochemically stimulated condensation of an aromatic aldehyde, malononitrile and some enolizable acidic compounds in ethanol at room temperature under constant current density. By utilizing common electrode materials and a simple constant current protocol, this method is a new alternative to conventional methods. 相似文献
67.
68.
Amit B. Rajput Subhenjit Hazra Niharika B. Krishna Pavani Chavali Sneha Datla Narendra Nath Ghosh 《Particuology》2012,10(1):29-34
An ethylene diamine tetra acetic acid (EDTA) precursor-based chemical method is reported for preparing single-phase nickel ferrite (NiFe2O4) nanopowder. The synthesized powder was characterized by thermogravimetric analysis, differential scanning calorimetric analysis, X-ray diffraction, particle size analysis and scanning electron microscopy. DC electrical resistivity and magnetic property of the synthesized NiFe2O4 were measured by using a two-probe method and a vibrating sample magnetometer respectively. The DC resistivity behaviour of the NiFe2O4 nanopowder was correlated with the change of microstructure, during sintering. This EDTA precursor-based method is capable of producing nanostructured single-phase NiFe2O4 powder at a comparatively low calcination temperature and offers the potential of a simple and cost-effective route, including the preparation of other ferrite nanoparticles. 相似文献
69.
70.
Narendra Prasad Brian K. Nicholson C. John McAdam 《Journal of organometallic chemistry》2010,695(17):1961-5456
2-Ferrocenyl-substituted pyrylium salts are produced when orthomanganated chalcones are reacted with ethynylferrocene in CCl4. When the reaction is carried out in benzene, intermediate ferrocenyl-substituted (η5-pyranyl)Mn(CO)3 species can be isolated which give the pyrylium cations on oxidation. The electrochemistry of the 2-ferrocenyl-pyrylium cations shows both oxidation (of the ferrocenyl) and reduction (of the pyrylium) processes, and the UV-visible spectra show a broad band at ca 680 nm which can be assigned to an intramolecular charge transfer transition. 相似文献