Mesoscale Polarization by Geometric Frustration in Columnar Supramolecular Crystals.

Christoph S Zehe,Kasper P Van Der Zwan,Klaus Kreger,Nicholas P Funnell,Andrew L Goodwin,Joshua A Hill,Jürgen Senker,Hans‐Werner Schmidt

doi:10.1002/anie.201612122

Christoph S Zehe, Kasper P Van Der Zwan + Show 6 more

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https://doi.org/10.1002/anie.201612122

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Abstract

Columnar supramolecular phases with polarization along the columnar axis have potential for the development of ultrahigh‐density memories as every single column might function as a memory element. By investigating structure and disorder for four columnar benzene‐1,3,5‐trisamides by total X‐ray scattering and DFT calculations, we demonstrate that the column orientation, and thus the columnar dipole moment, is receptive to geometric frustration if the columns aggregate in a hexagonal rod packing. The frustration suppresses conventional antiferroelectric order and heightens the sensitivity towards collective intercolumnar packing effects. The latter finding allows for the building up of mesoscale domains with spontaneous polarization. Our results suggest how the complex interplay between steric and electrostatic interactions is influenced by a straightforward chemical design of the molecular synthons to create spontaneous polarization and to adjust mesoscale domain size.

Highlights

By investigating structure and disorder for four columnar benzene-1,3,5-trisamides by total X-ray scattering and DFT calculations, we demonstrate that the column orientation, and the columnar dipole moment, is receptive to geometric frustration if the columns aggregate in a hexagonal rod packing
Our results suggest how the complex interplay between steric and electrostatic interactions is influenced by a straightforward chemical design of the molecular synthons to create spontaneous polarization and to adjust mesoscale domain size
One of the biggest challenges for axially polar materials remains the creation and control of spontaneous polarization in the absence of external stimuli. The latter requires the counterbalance of the electrostatic interactions between the dipoles of neighboring columns in a side-by-side arrangement, which inevitably favors an anti alignment of the columnar polarization, resulting in non-polar phases.[3]

Summary

Introduction

The latter requires the counterbalance of the electrostatic interactions between the dipoles of neighboring columns in a side-by-side arrangement, which inevitably favors an anti alignment of the columnar polarization, resulting in non-polar phases.[3] suitable columnar materials with spontaneous and stable polarization are rare up to now, and for the few observed cases,[8] its emergence remained unexplained.[7,8,9, 12,13,14] In a side-by-side arrangement of two columns, the electrostatic interactions prefer an anti alignment of the macrodipoles (Figure 1 c).

Results

Conclusion