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 - TY - GEN A1 - Bringmann, Gerhard A1 - Mutanyatta-Comar, Joan A1 - Maksimenka, Katja A1 - Wanjohi, John M. A1 - Heydenreich, Matthias A1 - Brun, Reto A1 - Müller, Werner E. G. A1 - Peter, Martin A1 - Midiwo, Jacob O. A1 - Yenesew, Abiy T1 - Joziknipholones A and B : the First Dimeric Phenylanthraquinones, from the Roots of Bulbine frutescens N2 - From the roots of the African plant Bulbine frutescens (Asphodelaceae), two unprecedented novel dimeric phenylanthraquinones, named joziknipholones A and B, possessing axial and centrochirality, were isolated, together with six known compounds. Structural elucidation of the new metabolites was achieved by spectroscopic and chiroptical methods, by reductive cleavage of the central bond between the monomeric phenylanthraquinone and -anthrone portions with sodium dithionite, and by quantum chemical CD calculations. Based on the recently revised absolute axial configuration of the parent phenylanthraquinones, knipholone and knipholone anthrone, the new dimers were attributed to possess the P-configuration (i.e., with the acetyl portions below the anthraquinone plane) at both axes in the case of joziknipholone A, whereas in joziknipholone B, the knipholone part was found to be M-configured. Joziknipholones A and B are active against the chloroquine resistant strain K1 of the malaria pathogen, Plasmodium falciparum, and show moderate activity against murine leukemic lymphoma L5178y cells. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 104 KW - antimalarial activity KW - chirality KW - joziknipholones KW - natural products KW - structure elucidation Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-42638 ER - TY - JOUR A1 - Rothe, Martin A1 - Zhao, Yuhang A1 - Müller, Johannes A1 - Kewes, Günter A1 - Koch, Christoph T. A1 - Lu, Yan A1 - Benson, Oliver T1 - Self-assembly of plasmonic nanoantenna-waveguide structures for subdiffractional chiral sensing JF - ACS nano N2 - Spin-momentum locking is a peculiar effect in the near-field of guided optical or plasmonic modes. It can be utilized to map the spinning or handedness of electromagnetic fields onto the propagation direction. This motivates a method to probe the circular dichroism of an illuminated chiral object. In this work, we demonstrate local, subdiffraction limited chiral coupling of light and propagating surface plasmon polaritons in a self-assembled system of a gold nanoantenna and a silver nanowire. A thin silica shell around the nanowire provides precise distance control and also serves as a host for fluorescent molecules, which indicate the direction of plasmon propagation. We characterize our nanoantenna-nanowire systems comprehensively through correlated electron microscopy, energy-dispersive X-ray spectroscopy, dark-field, and fluorescence imaging. Three-dimensional numerical simulations support the experimental findings. Besides our measurement of far-field polarization, we estimate sensing capabilities and derive not only a sensitivity of 1 mdeg for the ellipticity of the light field, but also find 10(3) deg cm(2)/dmol for the circular dichroism of an analyte locally introduced in the hot spot of the antenna-wire system. Thorough modeling of a prototypical design predicts on-chip sensing of chiral analytes. This introduces our system as an ultracompact sensor for chiral response far below the diffraction limit. KW - plasmonics KW - nanoparticle assemblies KW - core-shell KW - spin-orbit coupling KW - chirality KW - circular dichroism KW - nano-optics Y1 - 2021 U6 - https://doi.org/10.1021/acsnano.0c05240 SN - 1936-0851 SN - 1936-086X VL - 15 IS - 1 SP - 351 EP - 361 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Pikovskij, Arkadij T1 - Transition to synchrony in chiral active particles JF - Journal of physics. Complexity N2 - I study deterministic dynamics of chiral active particles in two dimensions. Particles are considered as discs interacting with elastic repulsive forces. An ensemble of particles, started from random initial conditions, demonstrates chaotic collisions resulting in their normal diffusion. This chaos is transient, as rather abruptly a synchronous collisionless state establishes. The life time of chaos grows exponentially with the number of particles. External forcing (periodic or chaotic) is shown to facilitate the synchronization transition. KW - active particles KW - chirality KW - synchronization KW - chaos KW - transient chaos Y1 - 2021 U6 - https://doi.org/10.1088/2632-072X/abdadb SN - 2632-072X VL - 2 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER -