Co-reporter:Adrian Thierbach, Christian Neiss, Lukas Gallandi, Noa Marom, Thomas Körzdörfer, and Andreas Görling
Journal of Chemical Theory and Computation October 10, 2017 Volume 13(Issue 10) pp:4726-4726
Publication Date(Web):August 7, 2017
DOI:10.1021/acs.jctc.7b00490
An accurate yet computationally very efficient and formally well justified approach to calculate molecular ionization potentials is presented and tested. The first as well as higher ionization potentials are obtained as the negatives of the Kohn–Sham eigenvalues of the neutral molecule after adjusting the eigenvalues by a recently [Görling Phys. Rev. B 2015, 91, 245120] introduced potential adjustor for exchange-correlation potentials. Technically the method is very simple. Besides a Kohn–Sham calculation of the neutral molecule, only a second Kohn–Sham calculation of the cation is required. The eigenvalue spectrum of the neutral molecule is shifted such that the negative of the eigenvalue of the highest occupied molecular orbital equals the energy difference of the total electronic energies of the cation minus the neutral molecule. For the first ionization potential this simply amounts to a ΔSCF calculation. Then, the higher ionization potentials are obtained as the negatives of the correspondingly shifted Kohn–Sham eigenvalues. Importantly, this shift of the Kohn–Sham eigenvalue spectrum is not just ad hoc. In fact, it is formally necessary for the physically correct energetic adjustment of the eigenvalue spectrum as it results from ensemble density-functional theory. An analogous approach for electron affinities is equally well obtained and justified. To illustrate the practical benefits of the approach, we calculate the valence ionization energies of test sets of small- and medium-sized molecules and photoelectron spectra of medium-sized electron acceptor molecules using a typical semilocal (PBE) and two typical global hybrid functionals (B3LYP and PBE0). The potential adjusted B3LYP and PBE0 eigenvalues yield valence ionization potentials that are in very good agreement with experimental values, reaching an accuracy that is as good as the best G0W0 methods, however, at much lower computational costs. The potential adjusted PBE eigenvalues result in somewhat less accurate ionization energies, which, however, are almost as accurate as those obtained from the most commonly used G0W0 variants.
Co-reporter:Christina M. Bock;Dr. Gangajji Parameshwarappa;Simon Bönisch;Dr. Christian Neiss;Dr. Walter Bauer;Dr. Frank Hampel;Dr. Andreas Görling;Dr. Svetlana B. Tsogoeva
Chemistry - A European Journal 2016 Volume 22( Issue 15) pp:5189-5197
Publication Date(Web):
DOI:10.1002/chem.201504798
Abstract
Aza- and carbobicyclic compounds possess favorable pharmaceutical properties, but they are difficult to access. Herein, we demonstrate an unprecedented organocatalytic two component six-step chemodivergent domino reaction, which provides a straightforward, sustainable and atom economical route to difficult-to-access complex bicyclic architectures: azabicycles and carbobicycles, whose ratios can be controlled by the applied electrophiles and catalysts. Detailed NMR and X-ray studies on the structures and relative stereochemistry of selected compounds are presented. Mechanistic investigations of the chemoselective branching step have been carried out with DFT methods in conjunction with semiempirical van der Waals interactions. This new domino reaction opens up a new vista of generating, in a single operation, new bioactive compounds with strong antiviral properties (EC50 up to 0.071 μm for human cytomegalovirus (HCMV)) outperforming clinically used ganciclovir (EC50 2.6 μm).
Co-reporter:Christoph Reiter;Sònia López-Molina;Bernhard Schmid;Dr. Christian Neiss;Dr. Andreas Görling;Dr. Svetlana B. Tsogoeva
ChemCatChem 2014 Volume 6( Issue 5) pp:1324-1332
Publication Date(Web):
DOI:10.1002/cctc.201301052
Abstract
Bifunctional thiourea- or sulfonamide-derived tertiary amines catalyze the enantioselective nitro-Michael addition of N-unprotected 3-substituted 2-oxindoles to nitrostyrene in up to 99 % yields, 94:6 er, and 87:13 dr. Overcoming the necessity to introduce and remove activating or protecting groups at the nitrogen moiety leads to a reduction of energy use, costs, and waste. Transition-state geometries for the formation of all possible stereoisomers in the nitro-Michael addition of N-unprotected 3-substituted 2-oxindole to nitrostyrene catalyzed by Takemoto’s tertiary amine–thiourea are calculated. It is shown that the relative positions and binding patterns of the reactants and the catalyst molecule are largely determined by van der Waals interactions.
Co-reporter:Dr. Nina V. Fischer;Utpal Mitra;Karl-Georg Warnick;Dr. Viacheslav Dremov;Dr. Michael Stocker;Thorsten Wölfle;Dr. Wolfgang Hieringer;Dr. Frank W. Heinemann;Dr. Nicolai Burzlaff;Dr. Andreas Görling;Dr. Paul Müller
Chemistry - A European Journal 2014 Volume 20( Issue 37) pp:11863-11869
Publication Date(Web):
DOI:10.1002/chem.201302379
Abstract
Novel κ3-N,N,O ligands tend to form 1D coordination polymer strands. Deposition of 1D structures on highly oriented pyrolytic graphite (HOPG) was achieved from diluted solutions and polymer strands have been studied on HOPG by AFM/STM. Single strands were mapped by STM and their electronic properties were subsequently characterized by current imaging tunneling spectroscopy (CITS). Periodic density functional calculations simulating a polymer strand deposited on a HOPG surface are in agreement with the zig-zag structure indicated by experimental findings. Both the observed periodicity and the Zn–Zn distances can be reproduced in the simulations. Van der Waals interactions were found to play a major role for the geometry of the isolated polymer strand, for the adsorption geometry on HOPG, as well as for the adsorption energy.