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Design and enantioselective synthesis of 3D π-extended carbohelicenes for circularly polarized luminescence

Nature Synthesis (2024)Cite this article

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Abstract

Circularly polarized luminescence (CPL) of chiral organic molecules has attracted attention as next-generation optoelectronic technology, including applications in biotechnology. Higher-order 3D π-extended carbohelicenes would be superb CPL emitters, combining high circular polarization, brightness and stability, but their highly distorted structure has hindered their synthesis and enantiocontrol. Here we report the design of 3D π-extended carbo[11] and [13]helicenes for the CPL emitters and their enantioselective synthesis (up to 87:13 enantiomeric ratio), overcoming high distortions. These helicenes are synthesized via the enantioselective triple [2 + 2 + 2] cycloaddition to construct low-distortion expanded carbo[13] and [15]helicene skeletons and the subsequent π-extension/helix diameter reduction by the Scholl reaction. X-ray crystallographic analyses demonstrate that the 3D π-extended carbo[11] and [13]helicenes with rigid molecular backbones are conglomerates, favouring preferential crystallization, and reveal van der Waals interactions throughout the hexa-peri-hexabenzocoronene layers. Furthermore, their CPL brightness reaches a maximum of 513 M−1 cm−1, the highest value among helicene derivatives.

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Fig. 1: Synthesis of longitudinally and laterally π-extended carbohelicenes.
Fig. 2: The synthesis of nonaynes.
Fig. 3: The enantioselective synthesis of 3D π-extended carbohelicenes.
Fig. 4: X-ray crystal structures of (±)-2b, (±)-17b and (±)-3b.
Fig. 5: Absorption, fluorescence, ECD and CPL spectra of 2a, 16a and 3a in CHCl3 at 25 °C.
Fig. 6: Absorption, fluorescence, ECD and CPL spectra of 2b, 17b and 3b in CHCl3 at 25 °C.
Fig. 7: Calculated electric (blue arrow, μe) and magnetic (red arrow, μm) transition dipole moments at the B3LYP/6-31G(d) level of theory.

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Data availability

The data that support the findings of this study are available in this paper and Supplementary Information (experimental procedures and characterization data). Crystallographic data for the structures reported in this paper have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2303728 [(±)-2a], CCDC 2303729 [(±)-2b], CCDC 2303730 [(M)-3a], CCDC 2303731 [(±)-3b], CCDC 2303732 [(±)-17b], CCDC 2303733 [(±)-23], CCDC 2303737 [(±)-24] and CCDC 2336973 [(±)-16a]. Copies of the data can be obtained free of charge via Cambridge Crystallographic Data Centre at https://www.ccdc.cam.ac.uk/structures/ (ref. 66).

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Acknowledgements

This work was supported by JSPS KAKENHI grant numbers JP19H00893, JP21K18949 and JP24H00005 to K.T., JP20H04661 and JP22K05032 to H.U., JP23H04020 to G.F. and JP22H00320 and JP22H05125 to M.U. and JST CREST grant number JPMJCR19R2 to M.U. This work was supported by JST, the establishment of university fellowships towards the creation of science and technology innovation, grant number JPMJFS2112 to F.M. We thank Takasago International Corporation for the gift of Segphos and H8-BINAP. A generous allotment of computational resources from TSUBAME (Tokyo Institute of Technology) is gratefully acknowledged.

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Authors and Affiliations

  1. Department of Chemical Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan

    Futo Morita, Yu Sato, Juntaro Nogami, Yuki Nagashima & Ken Tanaka

  2. Department of Chemistry, Tokyo Institute of Technology, Tokyo, Japan

    Yuko Kishida, Masato Abekura, Tomokazu Kinoshita, Gaku Fukuhara & Hidehiro Uekusa

  3. Comprehensive Research Organization for Science and Society Neutron Industrial Application Promotion Center, Tokai, Japan

    Haruki Sugiyama

  4. Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan

    Naoyuki Toriumi & Masanobu Uchiyama

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  1. Futo Morita
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Contributions

F.M. designed the project, conducted experimental works and computational studies, and wrote a draft paper. X-ray crystallographic analyses were performed by Y.K., H.S., M.A. and H.U. for (±)-2b, (M)-3a, (±)-3b, (±)-16a and (±)-17b, and Y.S. and J.N. for (±)-2a, (±)-23 and (±)-24. N.T., F.M., Y.N. and M.U. performed CPL measurements. T.K. and G.F. performed fluorescence lifetime measurements. K.T. designed, advised and directed the project, and wrote the paper. All authors edited the paper.

Corresponding author

Correspondence to Ken Tanaka.

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The authors declare no competing interests.

Peer review

Peer review information

Nature Synthesis thanks Jeanne Crassous, Xiaoyu Yang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Alison Stoddart, in collaboration with the Nature Synthesis team.

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Supplementary information

Supplementary Information

Synthetic experiments, 1H and 13C NMR spectra, chiral high-performance liquid chromatography charts, photophysical and chiroptical properties, crystal data, theoretical calculations and Supplementary Figs. 1–77 and Tables 1–39.

Supplementary Data 1

Crystal data for compound 2a, CCDC 2303728.

Supplementary Data 2

Crystal data for compound 2b, CCDC 2303729.

Supplementary Data 3

Crystal data for compound 3a, CCDC 2303730.

Supplementary Data 4

Crystal data for compound 3b, CCDC 2303731.

Supplementary Data 5

Crystal data for compound 17b, CCDC 2303732.

Supplementary Data 6

Crystal data for compound 23, CCDC 2303733.

Supplementary Data 7

Crystal data for compound 24, CCDC 2303737.

Supplementary Data 8

Crystal data for compound 16a, CCDC 2336973.

Source data

Source Data Fig. 5

Statistical source data. Raw data (.txt) of ultraviolet–visible absorption, fluorescence, ECD and CPL spectra of compounds 2a, 16a and 3a.

Source Data Fig. 6

Statistical source data. Raw data (.txt) of ultraviolet–visible absorption, fluorescence, ECD and CPL spectra of compounds 2b, 17b and 3b.

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Morita, F., Kishida, Y., Sato, Y. et al. Design and enantioselective synthesis of 3D π-extended carbohelicenes for circularly polarized luminescence. Nat. Synth (2024). https://doi.org/10.1038/s44160-024-00527-3

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