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How do intermolecular interactions evolve at the nematic to twist–bent phase transition?

DOI: 10.3390/ijms231911018 DOI Help

Authors: Katarzyna Merkel (University of Silesia) , Barbara Loska (University of Silesia) , Yuki Arakawa (Toyohashi University of Technology) , Georg H. Mehl (University of Hull) , Jakub Karcz (University of Technology) , Antoni Kocot (University of Silesia)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: International Journal Of Molecular Sciences , VOL 23

State: Published (Approved)
Published: October 2022
Diamond Proposal Number(s): 28688 , 30755

Open Access Open Access

Abstract: 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.

Journal Keywords: FTIR spectroscopy; DFT simulations; intermolecular interactions; liquid crystal dimers; twist–bend phase; self-assembling

Subject Areas: Materials

Instruments: B23-Circular Dichroism

Added On: 29/09/2022 13:19


Discipline Tags:

Materials Science

Technical Tags:

Spectroscopy Circular Dichroism (CD)