Antoni Kocot

Antoni Kocot

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Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 November 2023 in Chemical Communications
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JKJakub Karcz
Jakub Karcz
NRNatan Rychłowicz
Natan Rychłowicz
MCMałgorzata Czarnecka
Małgorzata Czarnecka
AKAntoni Kocot
Antoni Kocot
JHJakub Herman
Jakub Herman
PKPrzemysław Kula
Przemysław Kula
The design, synthesis and physicochemical properties of the highly polar ferroelectric nematic liquid crystal are reported. This compound exhibits enantiotropic N F phase, as the very first example with such behaviour.
30 September 2019 in Physical Chemistry Chemical Physics
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Katarzyna MerkelKatarzyna Merkel
Katarzyna Merkel
AKAntoni Kocot
Antoni Kocot
CWC. Welch
C. Welch
Georg MehlGeorg Mehl
Georg Mehl
The dielectric spectra of the twist–bend nematic phase (NTB) of (the bent-shaped) achiral liquid-crystal dimer 1′′-,7′′-bis(4-cyanobiphenyl-4′-yl)heptane (CB7CB) are studied for the determination of the different relaxation modes. Two molecular processes and one collective process were observed in the megahertz frequency range. Two molecular processes were assigned: one to the precessional rotation of the longitudinal components of the cyanobiphenyl groups and the second one to the spinning rotation of the transverse component of the CB7CB dimer. The peak, at a frequency of about 1 MHz, shows a peculiar temperature behavior at the NTB to N transition, reminiscent of the soft mode at the transition from the SmA to the SmC phase. This peak can be assigned to a collective fluctuation of the tilt angle of the coarse grained director N with respect to the pseudo-layer normal. This corresponds well with the electro-clinic effect observed as a response to an electric field in electro-optic experiments. The low frequency relaxation process, observed in the frequency range of 1 Hz–102 Hz can be identified as a Goldstone mode, related to long-scale fluctuation of the cone phase. The frequency drop of the mode on increasing the bias field is interpreted as unwinding of a helix and an indication of the formation of a field induced nematic splay bend phase (NSB). This finding is also confirmed by birefringence data in the presence of strong bias fields.
20 September 2022 in International Journal of Molecular Sciences
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Katarzyna MerkelKatarzyna Merkel
Katarzyna Merkel
BLBarbara Loska
Barbara Loska
YAYuki Arakawa
Yuki Arakawa
Georg MehlGeorg Mehl
Georg Mehl
JKJakub Karcz
Jakub Karcz
AKAntoni Kocot
Antoni Kocot
Polarized beam infrared (IR) spectroscopy provides valuable information on changes in the orientation of samples in nematic phases, especially on the role of intermolecular interactions in forming the periodically modulated twist–bent phase. Infrared absorbance measurements and quantum chemistry calculations based on the density functional theory (DFT) were performed to investigate the structure and how the molecules interact in the nematic (N) and twist–bend (NTB) phases of thioether dimers. The nematic twist–bend phase observed significant changes in the mean IR absorbance. On cooling, the transition from the N phase to the NTB phase was found to be accompanied by a marked decrease in absorbance for longitudinal dipoles. Then, with further cooling, the absorbance of the transverse dipoles increased, indicating that transverse dipoles became correlated in parallel. To investigate the influence of the closest neighbors, DFT calculations were performed. As a result of the optimization of the molecular cores system, we observed changes in the square of the transition dipoles, which well corresponds to absorbance changes observed in the IR spectra. Interactions of molecules dominated by pairing were observed, as well as the axial shift of the core to each other.
13 January 2021 in RSC Advances
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Katarzyna MerkelKatarzyna Merkel
Katarzyna Merkel
BLBarbara Loska
Barbara Loska
CWChris Welch
Chris Welch
Georg MehlGeorg Mehl
Georg Mehl
AKAntoni Kocot
Antoni Kocot
The understanding of the relationship between molecular structure and the formation of the nematic twist-bend phase is still at an early stage of development. This is mainly related to molecular geometry, while the correlation between the nematic twist-bend phase and the electronic structure is ambiguous. To explore the electronic effect on properties and stabilization of the nematic twist-bend phase we investigated 2′,3′-difluoro-4,4′′-dipentyl-p-terphenyl dimers (DTC5Cn). We used polarized fourier transform infrared spectroscopy, which can, at least in principle, provide information about the ordering in the twist-bend phase. All dimers show a significant drop in the average value of the transition dipole moment for parallel dipoles at the transition from the nematic to the twist-bend phase, and an increase for perpendicular dipoles, despite remaining unchanged for the monomer. Density functional theory calculations were used to determine the geometric and electronic properties of the hydrogen bonded complexes. We have provided experimental and theoretical evidence of stabilization of the nematic twist-bend phase by arrays of multiple hydrogen bonds (XF⋯HX, X–benzene ring).
20 July 2022 in International Journal of Molecular Sciences
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AKAntoni Kocot
Antoni Kocot
BLBarbara Loska
Barbara Loska
YAYuki Arakawa
Yuki Arakawa
Georg MehlGeorg Mehl
Georg Mehl
Katarzyna MerkelKatarzyna Merkel
Katarzyna Merkel
Infrared spectroscopy (IR) and quantum chemistry calculations that are based on the density functional theory (DFT) have been used to study the structure and molecular interactions of the nematic and twist-bend phases of thioether-linked dimers. Infrared absorbance measurements were conducted in a polarized beam for a homogeneously aligned sample in order to obtain more details about the orientation of the vibrational transition dipole moments. The distributions to investigate the structure and conformation of the molecule dihedral angle were calculated. The calculated spectrum was compared with the experimental infrared spectra and as a result, detailed vibrational assignments are reported.
5 April 2022 in Physical Review E
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AKAntoni Kocot
Antoni Kocot
BLBarbara Loska
Barbara Loska
YAYuki Arakawa
Yuki Arakawa
Katarzyna MerkelKatarzyna Merkel
Katarzyna Merkel
An analysis of the IR absorbance for the segmented functional groups of liquid crystal dimers mesogen and linker enabled the orientation order to be determined and information about the dipole interactions in the nematic and twist-bend nematic phases to be obtained. The long axis orientational order increases as the temperature decreases in the nematic phase, although much more slowly than for the classical nematics, and then reverses this trend in the twist-bend nematic phase due to the tilt of the molecules. In the nematic phase, the short axis of the molecule performs an isotropic uniform rotation and has a uniaxial alignment. In the twist-bend nematic phase, however, biaxial ordering occurs and grows significantly in accordance with the helical deformation of the director. Changes in the mean absorbance in the twist-bend nematic phase were observed: a decrease for the longitudinal dipole at the nematic-twist-bend nematic phase transition, thus emphasizing the antiparallel axial interaction of the dipoles, while the absorbance of the transverse dipoles remains unchanged up to 340 K, and then the latter become parallelly correlated.