• PRADEEP KUMAR

      Articles written in Journal of Chemical Sciences

    • Pyrone-based Cu(II) complexes, their characterization, DFT based conformational drift from square planar to square pyramidal geometry and biological activities

      PRADEEP KUMAR VISHWAKARMA JAN MOHAMMAD MIR RAM CHARITRA MAURYA

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      This work deals with the synthesis and characterization of a series of three N-Dehydroacetic acid-4-phenyl-3-thiosemicarbazide (H²dha-ptsc) Schiff base Cu(II) complexes based on combined experimentaland theoretical approach, having the general composition formula as [Cu(dha-ptsc)(L-L)], where L-L is H²O,2,2-bipyridine (bipy) or 1,10-phenanthroline (phen). H²O containing complex acts as origin for the latter twocomplexes and in due course, the geometry of the complex changes from square planar to square pyramidal.DFT calculations were carried out for both the geometrical forms. B3LYP/LANL2DZ level of theory was usedto carry out the required computations. From the overall DFT computations, square pyramidal geometry wasfound to be more stable as compared to the square planar conformation for the complexes under investigation.Super oxide dismutation, thermal behaviour and electrochemical activity were also studied. The results haveshown satisfactory super oxide scavenging potential, high degree of thermal resistance and efficient redoxproperties for the title complexes. Moreover, charge analysis and nonlinear optical properties were computedto establish a comprehensive note of atomic constituents differing in nature of charge delocalization.

    • Continuous group and electron-count rules in aromaticity

      PRADEEP KUMAR

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      In the present article a group theoretical approach has been used to explain different electron-count rules for aromaticity. A general group theoretical method is presented to derive and unite the different electron count rules (Hückel,Baird,Möbius, and Spherical aromaticity). It is shownthat continuous groups play important role in understanding of these electron count rules.

    • Non-oxidative methane dehydroaromatization reaction over highly active α-MoC1−x ZSM-5 derived from pretreatment

      PRADEEP KUMAR BUDDE ARVIND KUMAR SINGH SREEDEVI UPADHYAYULA

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      The catalytic active-phase of reduced Mo species plays a vital role in non-oxidative methane dehydroaromatization (MDA) reaction. Pretreatment effect of one of the gases containing N2, H2 and (90 vol%) CH4 + H2 over 15% Mo-loaded HZSM-5 catalyst has been investigated in the present work. Various spectroscopic investigations viz., XRD, TPR, TPO, XPS, etc., show that the pretreatment of 15% Mo-HZSM-5 catalyst with (90 vol%) CH4 + H2 gas stream exclusively leads to the formation of MoOxCyHzwhich acts as precursor moieties for the formation of highly active metastable fcc (α-MoC1-x) and MoOxCy phases during the induction period. Comparatively, H2 and N2-pretreated catalysts showed major formation of hcp (β-Mo2C) species that are found to be a less-active phase inMDA reaction. The active fcc (α-MoC1-x) phases are immuneto inert coking and assist primary ethylene products formed on carbonized Mo associated Brønsted acid sites to travel in the zeolite channels which is further aromatized over Brønsted acid sites deep inside the channels.XPS analysis of the catalyst shows that α-MoC1-x and β-Mo2C are major catalytic phases that are covered with graphitic carbon and amorphous carbon present on the surface. The active phases α-MoC1-x and MoOxCy,associated with Brønsted acid sites along with the vacant Brønsted acid sites in catalyst pretreated with (90 vol%) CH4 + H2 mixture are responsible for high activity in methane conversion (∼13%), excellent aromatic selectivity (38%), and high stability of the catalyst

    • Effect of anharmonicity on energy relaxation of a dissipative quantum oscillator

      RAMESH KUMAR PRADEEP KUMAR

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      The effect of anharmonicity on the energy relaxation of excited state has been studied by means of a dissipative oscillator. The present study also sheds light on the recent femtosecond stimulated Raman spectroscopy results of Kovalenko et al. (J. Chem. Phys. 139 011101 2013) on optical cooling of trans-stilbene.It has been shown that anharmonicity plays a crucial role in explaining the time-dependent frequency shift as well as the time evolution of bandwidth of νC=C mode of trans-stilbene in excited state, found in experiment.

    • Microwave-assisted rapid synthesis of arylazoxy sulfides

      N MURTHY GANDIKOTA NARENDER MENDU I V KASIVISWANATH R SEKHAR BOLLA PRADEEP KUMAR BRAHMAN

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      An efficient, fast, and straightforward procedure for the synthesis of arylazoxy sulfides can be achieved by coupling reaction between aryl nitrasocompounds and tribenzenesulphenamide under microwave irradiation. Using the present method, different kinds of aryl nitrasocompounds containing various dioxolanerings and various tribenzenesulphenamide derivatives were rapidly converted to the corresponding arylazoxy sulfides in good yield and short reaction time. The use of non-toxic solvent, simple and clean work-up, short reaction times and good yields are the advantages of this method.

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