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Incommensurate Chirality Density Wave Transition in a Hybrid Molecular Framework
Joshua A Hill1, Kirsten E Christensen1, Andrew L Goodwin1
1Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom.
Physical Review Letters
|September 27, 2017
Summary
Researchers discovered a new chiral symmetry breaking in a hybrid framework, forming an incommensurate chirality density wave (XDW) phase. This novel state involves modulated molecular chirality, with potential applications in photonic materials.
Area of Science:
- Solid-state chemistry
- Crystallography
- Materials science
Background:
- Hybrid molecular frameworks exhibit complex phase transitions.
- Chirality in solids can lead to unique physical properties.
Purpose of the Study:
- To characterize the incommensurate phase transition in tetraethylammonium silver(I) dicyanoargentate, [NEt4]Ag3(CN)4.
- To identify the nature of the symmetry breaking associated with this transition.
Main Methods:
- Single-crystal x-ray diffraction was employed to analyze the crystal structure.
- Analysis focused on the temperature-dependent structural changes around 235 K.
Main Results:
- A 235 K incommensurate phase transition was identified.
- The transition involves spontaneous resolution of chiral tetraethylammonium ([NEt4]+) conformations.
- This results in an incommensurate chirality density wave (XDW) phase, a new form of chiral symmetry breaking.
Conclusions:
- The XDW phase arises from coupled acoustic and molecular rotoinversion modes.
- This coupling is allowed for finite modulation vectors, leading to long-wavelength chirality modulations.
- The findings have implications for creating mesoscale chiral textures for photonic materials.
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