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On the Role of Hydrogen Bond Strength and Charge Transfer of a Diels-Alder Reaction On-Water: Semiempirical and Free Energy Calculations.

preprint
submitted on 11.04.2021, 18:24 and posted on 12.04.2021, 13:26 by Andrés Henao Aristizábal, Yomna Gohar, René Wilhelm, Thomas D. Kühne
Accelerated chemistry at the interface with water has received increasing attention. The mechanisms behind the enhanced reactivity On-Water are not yet clear. In this work we use a Langevin scheme in the spirit of second generation Car-Parrinello to accelerate the second-order density functional Tight-Binding (DFTB2) method in order to investigate the free energy of two Diels-Alder reaction On-Water: the cycloaddition between cyclopentadiene and ethyl cinnamate or thionocinnamate. The only difference between the reactants is the substitution of a carbonyl oxygen for a thiocarbonyl sulfur, making possible the distinction between them as strong and weak hydrogen-bond acceptors. We find a different mechanism for the reaction during the transition states and uncover the role of hydrogen bonds along with the reaction path. Our results suggest that acceleration of Diels-Alder reactions do not arise from an increased number of hydrogen bonds at the transition state and charge transfer plays a significant role. However, the presence of water and hydrogen-bonds is determinant for the catalysis of these reactions.

Funding

European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 716142)

Paderborn University's research award for "GreenIT''

Alexander von Humboldt Foundation Postdoctoral Research Fellowship.

Gauss Centre for Supercomputing e.V. (www.gauss-centre.eu) for funding this project by providing computing time through the John von Neumann Institute for Computing (NIC) on the GCS Supercomputer JUWELS at Jülich Supercomputing Centre (JSC), project "cpdftbwatercatalysis"

The generous allocation of computing time on the FPGA-based supercomputer `"Noctua'' by the Paderborn Center for Parallel Computing (PC2) is kindly acknowledged.

History

Email Address of Submitting Author

andres.henao.aristizabal@uni-paderborn.de

Institution

University of Paderborn

Country

Germany

ORCID For Submitting Author

0000-0002-2320-4693

Declaration of Conflict of Interest

The authors declare no conflict of interest.

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