School Of Basic And Applied Sciences

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Author: search.filters.author.Thakur, AHas files: Yes

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    Stability and electronic structure of tricycle-type allotropes of pnictogen monolayers
    (American Institute of Physics, 2019) Jamdagni, P; Thakur, A; Kumar ,Ashok; Ahluwalia, P.K.
    We report stability and electronic structure of tricycle-type allotrope of pnictogen monolayers within state-of-the-art density functional theory (DFT) calculations. The considered monolayer structure of two-dimensional (2D) As and Sb are found to be energetically more stable than the previously reported puckered and buckled structures, however, 2D Bi prefer zigzag-type high-buckled structure. Electronic band structure calculations suggest the considered monolayers structure to be narrow direct bandgap semiconductors with bandgap ranging 0.2-0.6 eV along with Dirac-cone features at band edges. Spin-orbit coupling (SOC) further reduce the bandgap by shifting the band edges towards Fermi level. We believe that our theoretical study will add more 2D materials with Dirac-cone features in the fascinating class of family and may guide the experimentalists to realize them for various nanoelectronic applications. © 2019 Author(s).
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    Cyclocondensation reactions of an electron deactivated 2-aminophenyl tethered imidazole with mono/1, 2-biselectrophiles: synthesis and DFT studies on the rationalisation of imidazo [1, 2-a] quinoxaline versus benzo [f] imidazo [1, 5-a][1, 3, 5] triazepine selectivity switches.
    (Royal Society of Chemistry, 2018) Joshi, G.; Chauhan, M; Kumar, R; Thakur, A; Sharma, S; Singh, R.; Wani, A.A.; Sharon, A.; Bharatam, P.V; Kumar, R.
    Microwave-promoted ring-closure reactions of 5-amino-1-(2-aminophenyl)-1H-imidazole-4-carbonitrile (7) with various mono/1,2-biselectrophiles are presented. The reaction of 7 with aldehydes, ketones and isocyanates produced the corresponding Pictet–Spengler (PS) products i.e. the imidazo[1,2-a]quinoxaline ring system via 6-endo-trig cyclisation. On the other hand, the reaction of 7 with CH(OEt)3, and CDI resulted in the formation of benzo[f]imidazo[1,5-a][1,3,5]triazepine scaffolds via a 7-exo-trig cyclisation process. The mechanistic aspects of these ring cyclisation processes have been analysed and studied to rationalise 6- versus 7-membered ring formation using density functional theory (DFT). DFT calculations revealed the involvement of N-Heterocyclic Carbene (NHC) in the PS reaction mechanism.