The loss of endgroup effects in long pyridyl-endcapped oligoynes on the way to carbyne

Abstract

The versatility of carbon is revealed in its all-carbon forms (allotropes), which feature unique properties (consider the differences between diamond, graphite, graphene and fullerenes). Beyond natural sources, there are many opportunities to expand the realm of carbon chemistry through the study of new carbon forms. In this work, the synthesis of oligo-/polyynes is used to model the elusive carbyne. The chemical stabilization of oligoynes by sterically encumbered endgroups, particularly the 3,5-bis(3,5-di-tert-butylphenyl)pyridyl group, is key to assemble an extended series of stable oligoynes. The final member of this series is the longest monodisperse polyyne isolated and characterized so far, featuring 24 contiguous alkyne units (48 carbons). Spectroscopic and X-ray crystallographic analysis show that endgroups influence the properties of oligoyne derivatives, but this effect diminishes as length increases toward the polyyne/carbyne limit. For instance, with ultraviolet–visible spectroscopy, molecular symmetry clearly documents the evolution of characteristics from oligoynes to polyynes (in which endgroup effects are absent). The combined experimental data are used to refine predictions for the D∞h structure of carbyne.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Molecular structure and symmetry of oligoynes, polyynes and carbyne.
Fig. 2: Synthesis of sterically encumbered di- and tetraynes Py**[2a–e] and Py**[4a–d].
Fig. 3: Synthesis of PEOs Py**[na].
Fig. 4: Ultraviolet–visible spectroscopic analysis of PEOs Py**[na] as well as extrapolations as a function of oligoyne length n using Meier’s equation.
Fig. 5: The solid-state structures of PEOs Py**[na] by X-ray crystallographic analysis as well as the extrapolation of bond length alternation (BLAavg) and Raman shifts as a function of oligoyne length n using Meier’s equation.

Data availability

All data generated or analysed during this study are included in this Article (and its Supplementary Information). The structures of tBu[5], tBu[6], Py**[2c], Py**[2e], Py**[2a], Py**[4a], Py**[6a] (P-1), Py**[6a] (P21/c) and Py**[8a]in the solid state were determined by single-crystal X-ray diffraction, and the crystallographic data have been deposited with the Cambridge Crystallographic Data Centre under CCDC numbers 1981170 (tBu[5]), 1981171 (tBu[6]), 1977432 (Py**[2c]), 1977434 (Py**[2e]), 1977437 (Py**[2a]), 1977437 (Py**[4a]), 1977438 (Py**[6a], P-1), 1977436 (Py**[6a], P21/c) and 1977435 (Py**[8a]). Copies of the data can be obtained free of charge on application to CCDC.

References

  1. 1.

    Hirsch, A. The era of carbon allotropes. Nat. Mater. 9, 868–871 (2010).

    CAS  PubMed  Google Scholar 

  2. 2.

    Kaiser, K. et al. An sp-hybridized molecular carbon allotrope, cyclo[18]carbon. Science 365, 1299–1301 (2019).

    CAS  PubMed  Google Scholar 

  3. 3.

    Kilde, M. D. et al. Synthesis of radiaannulene oligomers to model the elusive carbon allotrope 6,6,12-graphyne. Nat. Commun. 10, 3714 (2019).

    PubMed  PubMed Central  Google Scholar 

  4. 4.

    Malko, D., Neiss, C., Viñes, F. & Görling, A. Competition for graphene: graphynes with direction-dependent Dirac cones. Phys. Rev. Lett. 108, 086804 (2012).

    PubMed  Google Scholar 

  5. 5.

    Wang, X.-Y., Yao, X. & Müllen, K. Polycyclic aromatic hydrocarbons in the graphene era. Sci. China Chem. 62, 1099–1144 (2019).

    CAS  Google Scholar 

  6. 6.

    Schwertfeger, H., Fokin, A. A. & Schreiner, P. R. Diamonds are a chemist’s best friend: diamondoid chemistry beyond adamantane. Angew. Chem. Int. Ed. 47, 1022–1036 (2008).

    CAS  Google Scholar 

  7. 7.

    Darzi, E. R. & Jasti, R. The dynamic, size-dependent properties of [5]–[12]cycloparaphenylenes. Chem. Soc. Rev. 44, 6401–6410 (2015).

    CAS  PubMed  Google Scholar 

  8. 8.

    Chalifoux, W. A. & Tykwinski, R. R. Synthesis of extended polyynes: toward carbyne. C.R. Chim. 12, 341–358 (2009).

    CAS  Google Scholar 

  9. 9.

    Tykwinski, R. R. Carbyne: the molecular approach. Chem. Rec. 15, 1060–1074 (2015).

    CAS  PubMed  Google Scholar 

  10. 10.

    Szafert, S. & Gladysz, J. A. Update 1 of: carbon in one dimension: structural analysis of the higher conjugated polyynes. Chem. Rev. 106, PR1–PR33 (2006).

    CAS  Google Scholar 

  11. 11.

    Casari, C. S., Tommasini, M., Tykwinski, R. R. & Milani, A. Carbon-atom wires: 1-D systems with tunable properties. Nanoscale 8, 4414–4435 (2016).

    CAS  PubMed  Google Scholar 

  12. 12.

    Banhart, F. Elemental carbon in the sp1 hybridization. ChemTexts 6, 3 (2020).

    CAS  Google Scholar 

  13. 13.

    Liu, M., Artyukhov, V. I., Lee, H., Xu, F. & Yakobson, B. I. Carbyne from first principles: chain of C atoms, a nanorod or a nanorope. ACS Nano 7, 10075–10082 (2013).

    CAS  PubMed  Google Scholar 

  14. 14.

    Zheng, Q. et al. A synthetic breakthrough into an unanticipated stability regime: a series of isolable complexes in which C6, C8, C10, C12, C16, C20, C24, and C28 polyynediyl chains span two platinum atoms. Chem. Eur. J. 12, 6486–6505 (2006).

    CAS  PubMed  Google Scholar 

  15. 15.

    Weisbach, N. et al. Triisopropylsilyl (TIPS) alkynes as building blocks for syntheses of platinum triisopropylsilylpolyynyl and diplatinum polyynediyl complexes. Organometallics 38, 3294–3310 (2019).

    CAS  Google Scholar 

  16. 16.

    Chalifoux, W. A. & Tykwinski, R. R. Synthesis of polyynes to model the sp-carbon allotrope carbyne. Nat. Chem. 2, 967–971 (2010).

    CAS  PubMed  Google Scholar 

  17. 17.

    Shi, L. et al. Confined linear carbon chains as a route to bulk carbyne. Nat. Mater. 15, 634–639 (2016).

    CAS  PubMed  Google Scholar 

  18. 18.

    Pigulski, B., Gulia, N. & Szafert, S. Reactivity of polyynes: complex molecules from simple carbon rods. Eur. J. Org. Chem. 2019, 1420–1445 (2019).

    CAS  Google Scholar 

  19. 19.

    Wang, C. S. et al. Oligoyne single molecule wires. J. Am. Chem. Soc. 131, 15647–15654 (2009).

    CAS  PubMed  Google Scholar 

  20. 20.

    Milan, D. C. et al. The single-molecule electrical conductance of a rotaxane-hexayne supramolecular assembly. Nanoscale 9, 355–361 (2017).

    CAS  PubMed  Google Scholar 

  21. 21.

    Moreno-García, P. et al. Single-molecule conductance of functionalized oligoynes: length dependence and junction evolution. J. Am. Chem. Soc. 135, 12228–12240 (2013).

    PubMed  Google Scholar 

  22. 22.

    Wang, C., Jia, H., Li, H. & Wang, Y. 1,12-bis(4-Pyridyl)-1,3,5,7,9,11-dodecyl-hexayne: synthesis and properties. Jilin Huagong Xueyuan Xuebao 20, 33–36 (2012).

    Google Scholar 

  23. 23.

    Krempe, M. et al. Pyridyl-endcapped polyynes: stabilized wire-like molecules. Angew. Chem. Int. Ed. 55, 14802–14806 (2016).

    CAS  Google Scholar 

  24. 24.

    Simpkins, S. M. E., Weller, M. D. & Cox, L. R. β-Chlorovinylsilanes as masked alkynes in oligoyne assembly: synthesis of the first aryl-end-capped dodecayne. Chem. Commun. 4035–4037 (2007).

  25. 25.

    Robke, L. et al. Discovery of 2,4-dimethoxypyridines as novel autophagy inhibitors. Tetrahedron 74, 4531–4537 (2018).

    CAS  Google Scholar 

  26. 26.

    Eglinton, G. & Galbraith, A. R. Cyclic diynes. Chem. Ind. (London) 737–738 (1956).

  27. 27.

    Eisler, S. et al. Polyynes as a model for carbyne: synthesis, physical properties, and nonlinear optical response. J. Am. Chem. Soc. 127, 2666–2676 (2005).

    CAS  PubMed  Google Scholar 

  28. 28.

    Gibtner, T., Hampel, F., Gisselbrecht, J. P. & Hirsch, A. End-cap stabilized oligoynes: model compounds for the linear sp carbon allotrope carbyne. Chem. Eur. J. 8, 408–432 (2002).

    CAS  PubMed  Google Scholar 

  29. 29.

    Movsisyan, L. D. et al. Polyyne rotaxanes: stabilization by encapsulation. J. Am. Chem. Soc. 138, 1366–1376 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  30. 30.

    Biradha, K. & Santra, R. Crystal engineering of topochemical solid state reactions. Chem. Soc. Rev. 42, 950–967 (2013).

    CAS  PubMed  Google Scholar 

  31. 31.

    Chalifoux, W. A., McDonald, R., Ferguson, M. J. & Tykwinski, R. R. tert-Butyl-end-capped polyynes: crystallographic evidence of reduced bond-length alternation. Angew. Chem. Int. Ed. 48, 7915–7919 (2009).

    CAS  Google Scholar 

  32. 32.

    Bredas, J.-L. Mind the gap! Mater. Horiz. 1, 17–19 (2014).

    CAS  Google Scholar 

  33. 33.

    Zirzlmeier, J. et al. Optical gap and fundamental gap of oligoynes and carbyne. Nat. Commun. 11, 4797 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  34. 34.

    Milani, A., Tommasini, M. & Zerbi, G. Connection among Raman wavenumbers, bond length alternation and energy gap in polyynes. J. Raman Spectrosc. 40, 1931–1934 (2009).

    CAS  Google Scholar 

  35. 35.

    Kertesz, M., Choi, C. H. & Yang, S. Conjugated polymers and aromaticity. Chem. Rev. 105, 3448–3481 (2005).

    CAS  PubMed  Google Scholar 

  36. 36.

    Shi, L. et al. Electronic band gaps of confined linear carbon chains ranging from polyyne to carbyne. Phys. Rev. Mater. 1, 075601 (2017).

    Google Scholar 

  37. 37.

    Hoffmann, R. How chemistry and physics meet in the solid state. Angew. Chem. Int. Ed. 26, 846–878 (1987).

    Google Scholar 

  38. 38.

    Tykwinski, R. R. et al. Toward carbyne: synthesis and stability of really long polyynes. Pure Appl. Chem. 82, 891–904 (2010).

    CAS  Google Scholar 

  39. 39.

    Movsisyan, L. D. et al. Photophysics of threaded sp-carbon chains: the polyyne is a sink for singlet and triplet excitation. J. Am. Chem. Soc. 136, 17996–18008 (2014).

    CAS  PubMed  PubMed Central  Google Scholar 

  40. 40.

    Fazzi, D. et al. Ultrafast spectroscopy of linear carbon chains: the case of dinaphthylpolyynes. Phys. Chem. Chem. Phys. 15, 9384–9391 (2013).

    CAS  PubMed  Google Scholar 

  41. 41.

    Nagano, Y., Ikoma, T., Akiyama, K. & Tero-Kubota, S. Symmetry switching of the fluorescent excited state in α,ω-diphenylpolyynes. J. Am. Chem. Soc. 125, 14103–14112 (2003).

    CAS  PubMed  Google Scholar 

  42. 42.

    Meier, H., Stalmach, U. & Kolshorn, H. Effective conjugation length and UV/vis spectra of oligomers. Acta Polym. 48, 379–384 (1997).

    CAS  Google Scholar 

  43. 43.

    Martin, R. E. & Diederich, F. Linear monodisperse π-conjugated oligomers: model compounds for polymers and more. Angew. Chem. Int. Ed. 38, 1350–1377 (1999).

    Google Scholar 

  44. 44.

    Lucotti, A. et al. Evidence for solution-state nonlinearity of sp-carbon chains based on IR and Raman spectroscopy: violation of mutual exclusion. J. Am. Chem. Soc. 131, 4239–4244 (2009).

    CAS  PubMed  Google Scholar 

  45. 45.

    Gieseking, R. L., Risko, C. & Brédas, J.-L. Distinguishing the effects of bond-length alternation versus bond-order alternation on the nonlinear optical properties of π-conjugated chromophores. J. Phys. Chem. Lett. 6, 2158–2162 (2015).

    CAS  PubMed  Google Scholar 

  46. 46.

    Zeinalipour-Yazdi, C. D. & Pullman, D. P. Quantitative structure-property relationships for longitudinal, transverse, and molecular static polarizabilities in polyynes. J. Phys. Chem. B 112, 7377–7386 (2008).

    CAS  PubMed  Google Scholar 

  47. 47.

    Yang, S. & Kertesz, M. Bond length alternation and energy band gap of polyyne. J. Phys. Chem. A 110, 9771–9774 (2006).

    CAS  PubMed  Google Scholar 

  48. 48.

    Agarwal, N. R. et al. Structure and chain polarization of long polyynes investigated with infrared and Raman spectroscopy. J. Raman Spectrosc. 44, 1398–1410 (2013).

    CAS  Google Scholar 

Download references

Acknowledgements

This Article is dedicated to the memory of François Diederich. We are grateful for funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Foundation for Innovation (CFI), and the Deutsche Forschungsgemeinschaft (SFB 953, Synthetic Carbon Allotropes). We thank S. Frankenburger for synthesis and F. Hampel for X-ray structural determination of tBu[5] and tBu[6], Y. Zhou and R. McDonald for help with acquisition of the X-ray diffraction data for Py**[2a], Py**[6a] and Py**[2e], and L. Chen for crystallization of Py**[6a] (P21/c). Y.H. and Y.G. acknowledge funding from the China Scholarship Council (CSC). J.C. acknowledges MINECO and Junta de Andalucía of Spain project references PGC2018-098533-B-I00 and UMA18FEDERJA057.

Author information

Affiliations

Authors

Contributions

R.R.T. designed and oversaw the project. R.R.T and Y.G. designed the molecules, Y.G. and Y.H. synthesized and characterized the molecules. Y.G. carried out room temperature spectroscopy, thermal analyses and data analysis. J.C. and F.G.G. carried out low-temperature absorption and Raman spectroscopy. M.F. conducted X-ray crystallographic characterization, refinement and analysis. Y.G and R.R.T. wrote the paper with contributions from all authors. All authors analysed the results and commented on the manuscript.

Corresponding author

Correspondence to Rik R. Tykwinski.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figures 1–93 and Supplementary Tables 1–21

Supplementary Data 1

Crystallographic data (CIF) for compound tBu[5]; CCDC reference: 1981170

Supplementary Data 2

Crystallographic data (structure factors, FCF) for compound tBu[5]; CCDC reference: 1981170

Supplementary Data 3

Crystallographic data (CIF) for compound tBu[6]; CCDC reference: 1981171

Supplementary Data 4

Crystallographic data (structure factors, FCF) for compound tBu[6]; CCDC reference: 1981171

Supplementary Data 5

Crystallographic data (CIF) for compound Py**[2a]; CCDC reference: 1977437

Supplementary Data 6

Crystallographic data (CIF) for compound Py**[2c]; CCDC reference: 1977432

Supplementary Data 7

Crystallographic data (CIF) for compound Py**[2e]; CCDC reference: 1977434

Supplementary Data 8

Crystallographic data (CIF) for compound Py**[4a]; CCDC reference: 1977433

Supplementary Data 9

Crystallographic data (CIF) for compound Py**[6a] (P-1); CCDC reference: 1977438

Supplementary Data 10

Crystallographic data (CIF) for compound Py**[6a](P21/c); CCDC reference: 1977436

Supplementary Data 11

Crystallographic data (CIF) for compound Py**[8a]; CCDC reference: 1977435

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Gao, Y., Hou, Y., Gordillo Gámez, F. et al. The loss of endgroup effects in long pyridyl-endcapped oligoynes on the way to carbyne. Nat. Chem. 12, 1143–1149 (2020). https://doi.org/10.1038/s41557-020-0550-0

Download citation

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing