TY  - JOUR
A1  - Karras, Manfred
A1  - Dabrowski, Michal
A1  - Pohl, Radek
A1  - Rybacek, Jiri
A1  - Vacek, Jaroslav
A1  - Bednarova, Lucie
A1  - Grela, Karol
A1  - Stary, Ivo
A1  - Stara, Irena G.
A1  - Schmidt, Bernd
T1  - Helicenes as Chirality-Inducing Groups in Transition-Metal Catalysis
BT  - the first helically chiral Olefin Metathesis Catalyst
JF  - Chemistry - a European journal
N2  - Helical chirality is a novel enantioselectivity-inducing property in transition-metal-catalyzed transformations. The principle is illustrated herein for the example of asymmetric olefin metathesis. This work reports the synthesis of the first helically chiral Ru-NHC alkylidene complex from an aminohelicene-derived imidazolium salt, which was ligated to the first generation Hoveyda-Grubbs catalyst. Kinetic data were acquired for benchmark test reactions and compared to an achiral catalyst. The helically chiral Ru-catalyst was evaluated in asymmetric ring-closing metathesis (RCM) and ring-opening metathesis-cross-metathesis (ROM/CM) reactions, which proceeded with promising levels of enantioselectivity. Extensive NMR-spectroscopic investigations and a DFT geometry optimization were performed. These results led to a topographic steric map and calculation of percent-buried-volume values for each quadrant around the metal center.
KW  - asymmetric catalysis
KW  - carbene ligands
KW  - helicenes
KW  - metathesis
KW  - ruthenium
Y1  - 2018
U6  - https://doi.org/10.1002/chem.201802786
SN  - 0947-6539
SN  - 1521-3765
VL  - 24
IS  - 43
SP  - 10994
EP  - 10998
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Holec, Jan
A1  - Rybáček, Jiří
A1  - Vacek, Jaroslav
A1  - Karras, Manfred
A1  - Bednárová, Lucie
A1  - Budesinsky, Milos
A1  - Slusna, Michaela
A1  - Holy, Petr
A1  - Schmidt, Bernd
A1  - Stará, Irena G.
A1  - Starý, Ivo
T1  - Chirality-Controlled Self-Assembly of Amphiphilic Dibenzo[6]helicenes into Langmuir-Blodgett Thin Films
JF  - Chemistry - a European journal
N2  - Racemic and highly enantioenriched 3-methoxycarbonyl, 3-carboxy, and 3-hydroxymethyl derivatives of dibenzo[6]helicene were prepared. The Langmuir layers of these helicenes were formed at the air-water interface and transferred onto solid substrates to afford Langmuir-Blodgett films, which were then studied by ambient atomic force microscopy and (chir)optical spectroscopy. Significant differences were found in the behaviour of the Langmuir layers as well as in the morphology, UV/Vis, electronic circular dichroism (ECD), and fluorescence spectra of the Langmuir-Blodgett thin films depending on the molecular chirality and nature of the polar group. The experimental results were supported by molecular dynamics simulations.
KW  - arenes
KW  - chirality
KW  - helical structures
KW  - Langmuir-Blodgett films
KW  - self-assembly
Y1  - 2019
U6  - https://doi.org/10.1002/chem.201901695
SN  - 0947-6539
SN  - 1521-3765
VL  - 25
IS  - 49
SP  - 11494
EP  - 11502
PB  - Wiley-VCH
CY  - Weinheim
ER  -