Electronic Structures and Chiroptical Properties of Post-functionalized Helicene Quinones.
The synthesis of redox-active p- and o-quinones 2-phenylamino-4-phenylimino[6]helicene-1-one 1, 2-phenylamino[6]-helicene-1,4-dione 2, and 4-phenyl[6]helicene-1,2-dione 3 in their enantiopure forms by post-functionalization of (P)- and (M)-1,2-dimethoxy[6]helicene is presented. Structural characterization in solution and in the solid state was accomplished by 2D NMR spectroscopy methods and X-ray diffraction analysis, respectively. Interpretation of electrochemical redox data was accompanied by a detailed orbital picture, derived from DFT calculations. The electronic structures of compounds 1-3 were investigated by UV/Vis and electronic circular dichroism (ECD) spectroscopy, complemented by TD-DFT calculations. Quinones 1-3 were chemically reduced to study the EPR signatures of their respective radical anions. DFT methods were used for the atom assignment of the hyperfine coupling constants. The results are discussed within the context of electrochromic chiral switches and molecular recognition.
Laboratory of Organic Chemistry, ETH Zurich, Vladimir-Prelog-Weg 3, 8093, Zurich, Switzerland.
David
D
Schweinfurth
Laboratory of Organic Chemistry, ETH Zurich, Vladimir-Prelog-Weg 3, 8093, Zurich, Switzerland.
Marcella
M
Mazzolini
Institute of Physical and Theoretical Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria.
Dmytro
D
Neshchadin
Laboratory of Organic Chemistry, ETH Zurich, Vladimir-Prelog-Weg 3, 8093, Zurich, Switzerland.
Carolin
C
Hoyer
Institute of Physical and Theoretical Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria.
Roman
R
Geier
Institute of Physical and Theoretical Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria.
Karl
K
Gatterer
Laboratory of Organic Chemistry, ETH Zurich, Vladimir-Prelog-Weg 3, 8093, Zurich, Switzerland.
Nils
N
Trapp
Institute of Physical and Theoretical Chemistry, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria.
Georg
G
Gescheidt
Laboratory of Organic Chemistry, ETH Zurich, Vladimir-Prelog-Weg 3, 8093, Zurich, Switzerland. diederich@org.chem.ethz.ch.
François
F
Diederich
chiroptical properties; helicenes; post-functionalization; quinones; radical reactions