Amit Palkar
Clemson University
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Publication
Featured researches published by Amit Palkar.
Chemistry: A European Journal | 2009
Julio R. Pinzón; Claudia M. Cardona; María Ángeles Herranz; Marta E. Plonska-Brzezinska; Amit Palkar; Andreas J. Athans; Nazario Martín; Antonio Rodríguez-Fortea; Josep M. Poblet; Giovanni Bottari; Tomás Torres; S. Shankara Gayathri; Dirk M. Guldi; Luis Echegoyen
The first pyrrolidine and cyclopropane derivatives of the trimetallic nitride templated (TNT) endohedral metallofullerenes I(h)-Sc(3)N@C(80) and I(h)-Y(3)N@C(80) connected to an electron-donor unit (i.e., tetrathiafulvalene, phthalocyanine or ferrocene) were successfully prepared by 1,3-dipolar cycloaddition reactions of azomethine ylides and Bingel-Hirsch-type reactions. Electrochemical studies confirmed the formation of the [6,6] regioisomers for the Y(3)N@C(80)-based dyads and the [5,6] regioisomers in the case of Sc(3)N@C(80)-based dyads. Similar to other TNT endohedral metallofullerene systems previously synthesized, irreversible reductive behavior was observed for the [6,6]-Y(3)N@C(80)-based dyads, whereas the [5,6]-Sc(3)N@C(80)-based dyads exhibited reversible reductive electrochemistry. Density functional calculations were also carried out on these dyads confirming the importance of these structures as electron transfer model systems. Furthermore, photophysical investigations on a ferrocenyl-Sc(3)N@C(80)-fulleropyrrolidine dyad demonstrated the existence of a photoinduced electron-transfer process that yields a radical ion pair with a lifetime three times longer than that obtained for the analogous C(60) dyad.
Electrochemical and Solid State Letters | 2010
Marta E. Plonska-Brzezinska; Amit Palkar; Krzysztof Winkler; Luis Echegoyen
The electrochemical properties of small carbon nano-onions (CNOs) in the solid phase, nonmodified carbon nano-onions (n-CNOs), and CNOs functionalized with carboxylic acid groups [oxidized carbon nano-onions (ox-CNOs)] were investigated by cyclic voltammetry. The redox properties of CNO films depend on the functionalization of the carbon surface. In aqueous solutions, the n-CNO/tetra(n-octyl)ammonium bromide (TOABr) films show a behavior typical of an ideal double-layer capacitor with a specific capacitance close to 9.68 F g -1 . The ox-CNOs are electrochemically active at negative potentials due to carboxylic group reduction. Modification of the nano-onion surface with carboxylic groups results in a decrease in the specific capacitance of ox-CNO/TOABr films to 6.57 F g -1 .
Chemistry: A European Journal | 2010
Joanna Luszczyn; Marta E. Plonska-Brzezinska; Amit Palkar; Alina T. Dubis; Agneta Simionescu; Dan T. Simionescu; B. Kalska-Szostko; Krzysztof Winkler; Luis Echegoyen
Small carbon nano-onions (CNOs, 6-8 shells) were prepared in high yield and functionalized with carboxylic groups by chemical oxidation. After functionalization these nanostructures were soluble in aqueous solutions. 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 tetrazolium (MTS) tests showed excellent cytocompatibility of all CNOs analyzed at 30 and 300 microg mL(-1), so these carbon nanostructures can be safely used for biological applications. The first covalent functionalization of oxidized CNOs (ox-CNOs) with biomolecules, by using biotin-avidin interactions is reported here. Multilayers were prepared on a gold surface by layer-by-layer assembly and the process was monitored by surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM). Covalent binding of molecules to the short amine-terminated organosulfur monolayers was assessed by Fourier transform infrared spectroscopy using total attenuated reflactance mode (FT-IR/HATR).
Chemistry: A European Journal | 2009
Carla Cioffi; Amit Palkar; Frederic Melin; Amar Kumbhar; Luis Echegoyen; Manuel Melle-Franco; Francesco Zerbetto; G. M. Aminur Rahman; Christian Ehli; Vito Sgobba; Dirk M. Guldi; Maurizio Prato
We describe the synthesis and characterization of a novel ferrocene-carbon onion derivative, where ferrocene acts as an electron-donating moiety, while the carbon nano-onion (CNO) serves as the electron acceptor. CNOs were functionalized by 1,3-dipolar cycloaddition and the resulting products were characterized by transmission electron microscopy, thermogravimetric analysis, Raman and energy dispersive spectroscopies. The electronic properties of the Fc-CNO derivative were investigated by electrochemical and photophysical techniques, complemented by quantum chemical calculations. On average, the CNOs have a spherical appearance with six shells. Functionalization saturates one carbon atom in 36 carbon atoms on the outer cage of the CNO. Through-space interactions between the Fc moiety and the CNO core were detected electrochemically. Fluorescence was observed at low and high energies with an intrinsic decay that is faster at lower energies. Based on theory and experiment, we conclude that, after absorption of a photon at low energy, there is emission from CNOs characterized by larger external shells and a lower degree of functionalization. At high energy, emission comes from CNOs with smaller external shells and a higher degree of functionalization.
Journal of the American Chemical Society | 2007
David I. Schuster; Ke Li; Dirk M. Guldi; Amit Palkar; Luis Echegoyen; Christopher M. Stanisky; R. James Cross; Marja Niemi; Nikolai V. Tkachenko; Helge Lemmetyinen
Chemistry: A European Journal | 2005
Sean A. Vail; Paul J. Krawczuk; Dirk M. Guldi; Amit Palkar; Luis Echegoyen; João P. C. Tomé; Michael Fazio; David I. Schuster
Journal of Physical Chemistry B | 2006
Sean A. Vail; David I. Schuster; Dirk M. Guldi; Marja Isosomppi; Helge Lemmetyinen; Amit Palkar; Luis Echegoyen; X. H. Chen; John Z. H. Zhang
Chemistry-an Asian Journal | 2007
Amit Palkar; Frederic Melin; Claudia M. Cardona; Bevan Elliott; Amit K. Naskar; D.D. Edie; Amar Kumbhar; Luis Echegoyen
Helvetica Chimica Acta | 2005
Davide Bonifazi; Gianluca Accorsi; Nicola Armaroli; Fayi Song; Amit Palkar; Luis Echegoyen; Markus Scholl; Paul Seiler; Bernhard Jaun; François Diederich
Chemistry: A European Journal | 2009
Li Zhou; Chao Gao; Dandan Zhu; Weijian Xu; Fanqing Frank Chen; Amit Palkar; Luis Echegoyen; Eric Siu-Wai Kong