BITS Faculty Publications

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    Carbene-Mediated Transformations of 1-(Benzylideneamino)benzimidazoles
    (ACS, 2011-04-11) Sakhuja, Rajeev
    Carbene-mediated transformations of N-(3-butylbenzimidazol-3-ium-1-yl)-1-arylmethanimine iodides with carbon disulfide and benzoyl isothiocyanate gave the corresponding NHC·CS2 betaines in 68−85% and benzoyl-[1-butyl-3-[(E)-(aryl)methyleneamino]benzimidazol-1-ium-2-carbothioyl]azanides, respectively, in 74−85% yields. However, reaction with excess isopropyl isothiocyanate in NaH/THF at room temperature yielded the 1-butyl-1′,3′-diisopropyl-3-[(E)-(aryl)methyleneamino]spiro[benzimidazole-2,5′-imidazolidine]-2′,4′-dithiones (74−77%).
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    Crystal engineering of coordination polymers using 4,4'-bipyridine as a bond between transition metal atoms
    (RSC, 2006) Sarkar, Madhushree
    Coordination polymers have attracted an enormous interest among chemists due to their novel physical and chemical properties. This review describes the role of 4,4′-bipyridine in discovering various coordination polymers with novel topologies that range from one-dimensional to three dimensional. The geometries of coordination polymers of bipy include linear, zigzag, four-fold helices, molecular antenna, ladder, railroad, double, triple and quadruple chains, bilayer, square and rectangular grid, honeycomb layers, Lincoln Logs, 3D frames, diamondoid, 42·82 and cubic networks.
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    Exploring the Origin of “Aggregation Induced Emission” Activity and “Crystallization Induced Emission” in Organometallic Iridium(III) Cationic Complexes: Influence of Counterions
    (RSC, 2016) Laskar, Inamur Rahaman
    A new cationic iridium(III) complex exhibiting “aggregation induced emission (AIE)” activity, [Ir(PPh3)2(bipy)(H)2]A (bipy = 2,2′-bipyridine; A = counterions), has been synthesized in a straightforward synthetic route. Interestingly, the emission color of solid state samples of this complex varied with different counteranions [A = Cl–, BF4–, PF6–, N(CN)2–] and crystallization induced emission was observed. The emission properties for the compounds with A= Cl–, PF6– are discussed by analyzing the crystal packing, the frontier molecular orbitals, and the calculation of the relevant low-lying excited states using time-dependent density functional theory. The restriction of internal rotation of the phenyl rings in the phosphine ligands due to intermolecular interactions is suggested as the most plausible origin of the observed AIE effect in these crystals.
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    Crystal-to-crystal transformation from tri- to mononuclear Cu(ii) complex with a sugar-derived ligandvia proton transfer reaction and rearrangement of hydrogen bonding networks†
    (ACS, 2005) Sah, Ajay Kumar
    Treatment of a glycosylamine derived Cu(II) complex with ethylamine resulted in crystal-to-crystal transformation from trinuclear complex [Cu3(L1)2(EtNH2)2(MeOH)2]x2MeOHxCHCl3 (2x2MeOHxCHCl3) to a dimeric structure of mononuclear complex [Cu(HL1)(EtNH2)] (3) through proton transfer reaction and rearrangement of hydrogen bonding networks.
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    Modeling Polymer Crystallization Kinetics in the Meltblowing Process
    (ACS, 2020-12-06) Ghosal, Arkaprovo
    A novel model of the crystallization process in meltblowing process is proposed and implemented in numerical simulations. The spinline crystallization is studied using numerical solutions of the system of coupled quasi-one-dimensional equations describing the dynamics of multiple polymer jets moving in the surrounding high-speed air. Cooling, crystallization, and solidification accompany three-dimensional motion of polymer jets resulting in their vigorous stretching by the air flux including the aerodynamically driven bending/flapping. The numerical solutions predict distribution of the degree of crystallinity in polymer jets in flight, as well as in the laydown formed on the collecting screen, with the three-dimensional structure of the laydown being fully reconstructed. The effect of the collector screen temperature, die-to-collector distance (DCD), and the activation energy of the viscous flow in the polymer melt on the laydown features is studied in detail.