Dr. Puneet Gupta

Indian Institute of Technology Roorkee, India

E-mail: puneetgfcy[at]iitr.ac.in

Brief Bio-sketch:

Dr. Gupta is currently an assistant professor of computational chemistry at IIT Roorkee. Prior to joining IITR he was a molecular modeler for eight months at Momentive Performance Materials, Bangalore. Dr. Gupta developed his interest in computational chemistry during undergraduate studies at IIT Kanpur. He therefore joined the Holthausen group in 2009 for Ph.D. in computational catalysis at University of Frankfurt, Germany. Subsequently, he was awarded the Max Planck Research Fellowship (2015-18) to conduct scientific research with Prof. Walter Thiel and Prof. Frank Neese. Dr. Gupta applies DFT and CASSCF calculations to gain insights of metal-catalysed reactions. He has published research papers in Eur. J. Chem., Angew. Chem. and JACS.

HYDROXYLATION OF NON-ACTIVATED C−H BONDS IN A COPPER COMPLEX: A DFT BASED MECHANISTIC STUDY

Bioinorganic research has demonstrated impressively that small synthetic complexes containing a [Cu₂O₂] core can mediate the selective hydroxylation of aliphatic and aromatic C−H bonds, mimicking the function of metalloenzymes like tyrosinase or DβH. We have studied the mechanistic scenario underlying the regio- and stereoselectivity of the aliphatic C−H_β bond hydroxylation in Schnecker's system [1] by DFT.

Prior to the aliphatic C−H bond activation a peroxo/bis-(μ-oxo) core-isomerization occurs, which represents a notorious problem for DFT [2]. Several authors have put forward differing recommendations as to the choice of functionals for related systems [2] and in this context it remains an open question whether or not to apply a broken-symmetry approach for the peroxo- isomer with its coupled copper(II) ions.

In a careful benchmark study, we tested various flavors of DFT and relativistic schemes against experimental reference data obtained by Stack and coworkers, who studied the core isomerization and subsequent aliphatic C−H bond activation for a representative set of systems. Our benchmarked DFT method was successful in providing a convincing mechanistic picture in line with all available experimental data [3]. The benchmarked method was successfully used in studying other [Cu₂O₂] mediated hydroxylation reactions as well [4].

 

References:

[1] B. Schnecker, T. Zheldakova, Y. Liu, M. Ktteritzsch, W. Gther and H. Grls, Angew. Chem. Int. Ed. 2003, 42, 3240-3244. [2] a) C. J. Cramer, M. Wloch, P. Piecuch, C. Puzzarini and L. Gagliardi, J. Phys. Chem. A 2006, 110, 1991-2004. b) D. G. Liakos and F. Neese, J. Chem. Theory Comput. 2011, 7, 1511-1523. [3] P. Gupta, M. Diefenbach, M. C. Holthausen, M. Frster, Chem. Eur. J. 2017, 23, 1427-1435. [4] J. Becker, P. Gupta, F. Angersbach, F. Tuczek, C. Nther, M. C. Holthausen and S. Schindler, Chem. Eur. J. 2015, 21, 11735-11744.