Research ArticleChemistry

A high-spin ground-state donor-acceptor conjugated polymer

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Science Advances  24 May 2019:
Vol. 5, no. 5, eaav2336
DOI: 10.1126/sciadv.aav2336
  • Fig. 1 Synthesis of high-spin DA CP using a Stille cross-coupling copolymerization reaction.

    (A) The molecular building blocks and rapid polymerization approach used to synthesize the polymer. (B) Measured magnetic properties exhibiting intramolecular FM exchange coupling and a high-to-low spin energy gap of 9.30 × 10−3 kcal mol−1.

  • Fig. 2 Solid-state properties of polymer thin films.

    (A) Absorption spectra of thin film cast from chlorobenzene onto a NaCl substrate and (B) two-dimensional GIWAXS profile obtained using the same processing conditions and a silicon substrate. (C) CV indicates a HOMO-LUMO energy gap of 0.56 eV. (D) Current-voltage characteristics in a 30-μm channel with σ of ~10−2 S cm−1. (E) One-dimensional line cuts of the integrated in-plane and out-of-plane two-dimensional GIWAXS profile mainly showing a peak at q ~1.79 Å−1 that is related to interchain spacing of 3.51 Å. a.u., arbitrary units.

  • Fig. 3 Magnetic properties of the polymer.

    (A) EPR (X band) spectra from 4 to 50 K and (B) temperature-dependent fit to the Bleaney-Bowers equation with ΔEST of 9.30 × 10−3 kcal mol−1. (C) SQUID magnetometry of solid sample. Main plot: Magnetic susceptibility, χ versus T, from 3 to 225 K fit to the Curie-Weiss law (blue line). Inset: Observed χT versus T dependence. (D) Magnetic field (H) dependence of the magnetization (M) at 2, 3 and 5 K, plotted as M/Msat versus H, with Brillouin functions for S = 1/2, 0.94, and 3/2. (E) Log-log plot of the X band 1/T1e recovery rates versus temperature fit by the temperature dependence of the Orbach-Aminov process with an energy gap of 4.67 K. (F) Two-pulse electron spin echo instantaneous diffusion data at 10 K indicate a one-dimensional spin distribution (d = 1) along a linear chain. ESEEM, electron spin echo envelope modulation.

  • Fig. 4 Electronic structure of the oligomer (n = 8) at the UB3LYP/6-31G** level of theory.

    (A) Calculated α-SOMO (top) and β-SOMO (bottom) profiles of the open-shell singlet. (B) Spin density distribution of the singlet and (C) triplet states with most probable locations for the unpaired electrons highlighted with open circles (red, up spin; blue, down spin).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaav2336/DC1

    Fig. S1. Modified multigram synthesis of M1.

    Fig. S2. 1H and 13C NMR of (1).

    Fig. S3. 1H and 13C NMR of (2).

    Fig. S4. 1H NMR (600 MHz, C2D2Cl4, 398 K) of the polymer.

    Fig. S5. Solution and solid-state properties of the polymer.

    Fig. S6. Stability studies of the polymer.

    Fig. S7. Calculated data for the oligomers (n = 2 to 8) at the UB3LYP/6-31G** level of theory.

    Fig. S8. Optimized ground-state geometric structures for the trimer (n = 3) and pictorial representations of the frontier MOs and spin density distribution.

    Fig. S9. Optimized ground-state geometric structures for the tetramer (n = 4) and pictorial representations of the frontier MOs and spin density distribution.

    Fig. S10. Optimized ground-state geometric structures for the hexamer (n = 6) and pictorial representations of the frontier MOs and spin density distribution.

    Fig. S11. Bond length plots of the dimer (n = 2) singlet (orange) and triplet (blue) states.

    Fig. S12. Bond length plots of the trimer (n = 3) singlet (orange) and triplet (blue) states.

    Fig. S13. Bond length plots of the tetramer (n = 4) singlet (orange) and triplet (blue) states.

    Fig. S14. Bond length plots of the hexamer (n = 6) singlet (orange) and triplet (blue) states.

    Fig. S15. Bond length plots of the octamer (n = 8) singlet (orange) and triplet (blue) states.

    Fig. S16. Chemical structures of polymers with various substitution patterns and calculated diradical character index (y) for the tetramers (n = 4).

    Table S1. Inductively coupled plasma optical emission spectroscopy and x-ray photoelectron spectroscopy trace metal analysis.

    Table S2. Selected electronic properties of oligomers as a function of the number of repeat units.

    Table S3. Tabulated bond lengths for the octamer (n = 8).

    Table S4. Tabulated bond lengths for the auxiliary rings of the octamer (n = 8).

    Table S5. Tabulated NICS values of the dimer (n = 2).

    Table S6. Tabulated NICS values of the trimer (n = 3).

    Table S7. Tabulated NICS values of the tetramer (n = 4).

    Table S8. Tabulated NICS values of the hexamer (n = 6).

    Table S9. Tabulated NICS values of the octamer (n = 8).

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Modified multigram synthesis of M1.
    • Fig. S2. 1H and 13C NMR of (1).
    • Fig. S3. 1H and 13C NMR of (2).
    • Fig. S4. 1H NMR (600 MHz, C2D2Cl4, 398 K) of the polymer.
    • Fig. S5. Solution and solid-state properties of the polymer.
    • Fig. S6. Stability studies of the polymer.
    • Fig. S7. Calculated data for the oligomers (n = 2 to 8) at the UB3LYP/6-31G** level of theory.
    • Fig. S8. Optimized ground-state geometric structures for the trimer (n = 3) and pictorial representations of the frontier MOs and spin density distribution.
    • Fig. S9. Optimized ground-state geometric structures for the tetramer (n = 4) and pictorial representations of the frontier MOs and spin density distribution.
    • Fig. S10. Optimized ground-state geometric structures for the hexamer (n = 6) and pictorial representations of the frontier MOs and spin density distribution.
    • Fig. S11. Bond length plots of the dimer (n = 2) singlet (orange) and triplet (blue) states.
    • Fig. S12. Bond length plots of the trimer (n = 3) singlet (orange) and triplet (blue) states.
    • Fig. S13. Bond length plots of the tetramer (n = 4) singlet (orange) and triplet (blue) states.
    • Fig. S14. Bond length plots of the hexamer (n = 6) singlet (orange) and triplet (blue) states.
    • Fig. S15. Bond length plots of the octamer (n = 8) singlet (orange) and triplet (blue) states.
    • Fig. S16. Chemical structures of polymers with various substitution patterns and calculated diradical character index (y) for the tetramers (n = 4).
    • Table S1. Inductively coupled plasma optical emission spectroscopy and x-ray photoelectron spectroscopy trace metal analysis.
    • Table S2. Selected electronic properties of oligomers as a function of the number of repeat units.
    • Table S3. Tabulated bond lengths for the octamer (n = 8).
    • Table S4. Tabulated bond lengths for the auxiliary rings of the octamer (n = 8).
    • Table S5. Tabulated NICS values of the dimer (n = 2).
    • Table S6. Tabulated NICS values of the trimer (n = 3).
    • Table S7. Tabulated NICS values of the tetramer (n = 4).
    • Table S8. Tabulated NICS values of the hexamer (n = 6).
    • Table S9. Tabulated NICS values of the octamer (n = 8).

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