Research ArticleChemistry

Atomically precise bottom-up synthesis of π-extended [5]triangulene

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Science Advances  26 Jul 2019:
Vol. 5, no. 7, eaav7717
DOI: 10.1126/sciadv.aav7717
  • Fig. 1 Illustration of open-shell ZTGMs and the synthetic strategy to π-extended [5]triangulene.

    (A) Open-shell ZTGMs with different numbers of zigzag carbon atom (N) and predicted spin multiplicity (S). Yellow, monoradical phenalenyl (N = 2); red, biradical triangulene (N = 3); violet, π-extended triradical [4]triangulene (N = 4); blue, tetraradical [5]triangulene (N = 5). (B) Schematic illustration of the surface-assisted transformation of rationally designed precursor (compound 1) to [5]triangulene. The two yellow spots indicate the sites where the on-surface dehydrogenation initiated, and the six red spots represent the methyl groups that undergo the cyclodehydrogenation process.

  • Fig. 2 Structural characterization of single π-extended [5]triangulene synthesized on Cu(111) and Au(111) surfaces.

    (A and D) Large-scale STM images of [5]triangulene molecules (A) on Cu(111) and (D) on Au(111) [(A) Vs = −1 V and I = 1 nA; scale bar, 5 nm; (D) Vs = 1 V and I = 0.2 nA; scale bar, 1.5 nm]. (B and E) Zoom-in STM images of a single [5]triangulene (B) on Cu(111) and (E) on Au(111) [(B) Vs = −0.8 V and I = 1 nA; (E) Vs = −0.8 V and I = 1 nA; scale bar, 4 Å]. (C and F) nc-AFM images of a single [5]triangulene (C) on Cu(111) and (F) on Au(111) acquired using a CO-functionalized tip [(C) ∆z = 0.15 Å, Vs = 30 mV, I = 0.3 nA; (F) ∆z = 0.15 Å, Vs = 10 mV, I = 0.5 nA; scale bar, 4 Å]. fcc, face-centered cubic; hcp, hexagonal close-packed.

  • Fig. 3 Characterization of electronic properties of individual [5]triangulene.

    (A) Point dI/dV spectra acquired over different sites of the [5]triangulene molecule and the Au(111) substrate. dI/dV curves taken at the edge (solid blue line) and at the center (solid black line) of [5]triangulene and taken on the clean Au(111) surface (red dotted line). a.u., arbitrary units. (B and C) Color-coded dI/dV spectra (spaced by 0.11 nm) taken along the zigzag edge (B) and across the center of [5]triangulene [(C), starting from the apex]. The actual positions where the dI/dV spectra were taken are indicated by gray dots in the inset STM image in (A). SS, surface-state.

  • Fig. 4 Electronic structure of [5]triangulene.

    (A to D) Experimental dI/dV maps recorded at different energy positions [−2.2 V for (A), −0.62 V for (B), 1.07 V for (C), and 2.2 V for (D); scale bar, 4 Å]. (E to H) Simulated dI/dV maps of [5]triangulene acquired at different energy positions corresponding to different sets of orbitals: (E) ψ2↓ and ψ3↓, (F) ψ4↑ to ψ7↑, (G) ψ4↓ to ψ7↓ (note: the weight of ψ5↓ is set to 0.7; refer to fig. S8 for more details), and (H) ψ8↑ and ψ9↑. Scale bar, 4 Å. (I) Calculated spin-polarized molecular orbital energies of an isolated [5]triangulene. Blue and red refers to spin-up and spin-down states, respectively. (J) DFT-calculated wave functions of four pairs of spin-polarized orbitals [ψ4 ↑ ( ↓ ), ψ5 ↑ ( ↓ ), ψ6 ↑ ( ↓ ), and ψ7 ↑ ( ↓ )]. Red and blue colors indicate the wave functions with positive or negative values, respectively.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/7/eaav7717/DC1

    Section S1. Synthesis and characterization of the precursor (compound 1)

    Section S2. Additional nc-AFM images and simulated AFM images of [5]triangulene

    Section S3. dI/dV spectra and maps of [5]triangulene synthesized on the Au(111) surface

    Section S4. Theoretical calculation of electronic properties of [5]triangulene

    Scheme S1. The synthetic route of the precursor (compound 1).

    Fig. S1. Experimental and simulated AFM images of [5]triangulene.

    Fig. S2. STS spectra collected over the [5]triangulene molecule on the Au(111) surface.

    Fig. S3. Constant current dI/dV maps of P1 to P4 with the corresponding STM images.

    Fig. S4. Calculated energy diagram and spin density distribution of [5]triangulene with different magnetic configurations.

    Fig. S5. Wave function patterns and orbital densities of ψ4 ↑ ( ↓ ) to ψ7 ↑ ( ↓ ).

    Fig. S6. Wave functions and charge densities of molecular orbitals in the singlet closed-shell, singlet open-shell, and quintuplet states.

    Fig. S7. The calculated energy diagrams of a free [5]triangulene via DFT, HSE06, and GW methods.

    Fig. S8. Simulated dI/dV maps of [5]triangulene taken at an energetic position of the P2 state contributed by different weights of orbitals ψ4↓ to ψ7↓.

    Table S1. Total system energies of quintuplet (Q), triplet (T), singlet open-shell (SO), and singlet closed-shell (SC) states with respect to that of the SC state.

    Table S2. The calculated energy gap of [3]triangulene and [5]triangulene.

    Appendix S1. 1H-13C nuclear magnetic resonance spectra and mass spectra for all new compounds

    References (3950)

  • Supplementary Materials

    This PDF file includes:

    • Section S1. Synthesis and characterization of the precursor (compound 1)
    • Section S2. Additional nc-AFM images and simulated AFM images of 5triangulene
    • Section S3. dI/dV spectra and maps of 5triangulene synthesized on the Au(111) surface
    • Section S4. Theoretical calculation of electronic properties of 5triangulene
    • Scheme S1. The synthetic route of the precursor (compound 1).
    • Fig. S1. Experimental and simulated AFM images of 5triangulene.
    • Fig. S2. STS spectra collected over the 5triangulene molecule on the Au(111) surface.
    • Fig. S3. Constant current dI/dV maps of P1 to P4 with the corresponding STM images.
    • Fig. S4. Calculated energy diagram and spin density distribution of 5triangulene with different magnetic configurations.
    • Fig. S5. Wave function patterns and orbital densities of ψ4 ↑ ( ↓ ) to ψ7 ↑ ( ↓ ).
    • Fig. S6. Wave functions and charge densities of molecular orbitals in the singlet closed-shell, singlet open-shell, and quintuplet states.
    • Fig. S7. The calculated energy diagrams of a free 5triangulene via DFT, HSE06, and GW methods.
    • Fig. S8. Simulated dI/dV maps of 5triangulene taken at an energetic position of the P2 state contributed by different weights of orbitals ψ4↓ to ψ7↓.
    • Table S1. Total system energies of quintuplet (Q), triplet (T), singlet open-shell (SO), and singlet closed-shell (SC) states with respect to that of the SC state.
    • Table S2. The calculated energy gap of 3triangulene and 5triangulene.
    • Appendix S1. 1H-13C nuclear magnetic resonance spectra and mass spectra for all new compounds
    • References (3950)

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