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Multi-stage and multi-colour liquid crystal reflections using a chiral triptycene photoswitchable dopant

Nature Chemistry volume 16, pages 2084–2090 (2024)Cite this article

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Abstract

The photomodulation of the helical pitch of cholesteric liquid crystals results in dynamic and coloured canvases that can potentially be used in applications ranging from energy-efficient displays to colour filters, anti-counterfeiting tags and liquid crystal (LC) lasers. Here we report on the analysis of a series of photoswitchable chiral dopants that combine the large geometrical change and bistability of hydrazone switches with the efficient helical pitch induction of the chiral motif, triptycene. We elucidate the effects that conformational flexibility, dispersion forces and π–π interactions have on the chirality transfer ability of the dopant. We then use the irradiation time with visible light (442 nm) combined with a simple digital light processing microscope projection set-up to draw numerous stable multi-coloured images on an LC canvas, showcasing the fine control this dopant yields over the LC assembly.

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Fig. 1: Photochromic triptycene chiral dopants, their synthesis, characterization and photoisomerization studies.
Fig. 2: Photochemical response and fatigue resistance of 5CB doped (S, S)-1: polarized optical micrographs, transmittance spectra and RGB images.
Fig. 3: Transmittance spectra and DLP patterning of 5CB doped (S, S)-1 for multi-colour image generation.

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Data availability

The data that support the findings of this study are available within the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

I.A. is thankful for the generous support from National Science Foundation (NSF) Division of Materials Research (DMR) (2104464). A.R.L. gratefully acknowledges support from the Welch Research Foundation (N-2038-202004010). We thank L.D. Custis for experimental support. I.A. is thankful to T. Swager (Massachusetts Institute of Technology) for suggesting the use of triptycene as the chiral motif in LC dopants at a Telluride workshop in 2016, and T. Ikai (Nagoya University) for supplying racemic 2,6-diaminotriptycene at a very early stage of this research.

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Authors and Affiliations

  1. Department of Chemistry, Dartmouth College, Hanover, NH, USA

    Indu Bala, Brandon Balamut & Ivan Aprahamian

  2. Department of Chemistry, Southern Methodist University, Dallas, TX, USA

    Joshua T. Plank, Drake Henry & Alexander R. Lippert

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  1. Indu Bala
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Contributions

I.B., J.T.P., D.H. and B.B. planned and carried out the experimental work and characterization studies. I.A. and A.R.L. directed the research. All authors contributed to the analysis of the results and the writing of the manuscript.

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Correspondence to Ivan Aprahamian.

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A.R.L. declares a financial stake in BioLum Sciences, LLC. The remaining authors declare no competing interests.

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Nature Chemistry thanks Masoud Kazem-Rostami, Quan Li and the other, anonymous, reviewers for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–99, Tables 1–15, Scheme 1, Discussion and experimental procedures.

Source data

Source Data Fig. 1

Circular dichroism data underlying Fig. 1b,c.

Source Data Fig. 2

Transmittance data underlying Fig. 2b.

Source Data Fig. 3

Transmittance data underlying Fig. 3a.

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Bala, I., Plank, J.T., Balamut, B. et al. Multi-stage and multi-colour liquid crystal reflections using a chiral triptycene photoswitchable dopant. Nat. Chem. 16, 2084–2090 (2024). https://doi.org/10.1038/s41557-024-01648-0

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