ORTHO-TERPHENYLS FOR THE PREPARATION OF GRAPHENE NANORIBBONS

Abstract

The present invention concerns ortho-Terphenyls of general formula (I); wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently selected from the group consisting of H; CN; NO.sub.2; and saturated, unsaturated or aromatic C.sub.1-C.sub.40 hydrocarbon residues, which can be substituted 1- to 5-fold with F, CI, OH, NH.sub.2, CN and/or NO.sub.2, and wherein one or more CH.sub.2-groups can be replaced by O, NH, S, C(O)O, OC(O) and/or C(O); and X and Y are the same or different, and selected from the group consisting of F, CI, Br, I, and OTf (trifluoromethanesulfonate); and their use for the preparation of graphene nanoribbons as well as a process for the preparation of graphene nanoribbons from said ortho-Terphenyls.

##STR00001##

Claims

1. A process for the preparation of a graphene nanoribbon, the process comprising: (a) polymerizing an ortho-terphenyl of general formula (I): ##STR00015## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H; unsubstituted C.sub.1-C.sub.40 alkyl residues; and unsubstituted C.sub.1-C.sub.40 alkoxy residues; and X and Y are each independently selected from the group consisting of F, Cl, Br, I, and OTf thereby forming a polymeric precursor comprising repeating units of general formula (II) ##STR00016## and (b) cyclodehydrogenating the polymeric precursor of general formula (II) thereby forming a graphene nanoribbon comprising repeating units of general formula (III) ##STR00017##

2. The process according to claim 1, wherein R.sup.1 and R.sup.2 are each independently selected from the group consisting of H, unsubstituted C.sub.1-C.sub.20 alkyl residues, and unsubstituted C.sub.1-C.sub.20 alkoxy residues; and wherein R.sup.3 and R.sup.4 are H.

3. The process according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are H.

4. The process according to claim 1, wherein X and Y are the same.

5. The process according to claim 1, wherein X and Y are Br.

6. (canceled)

7. The process according to claim 1, wherein the olvmerizing (a) is performed in a solution.

8. The process according to claim 1, wherein the cyclodehydrogenating (b) is performed in a solution.

9. The process according to claim 1, wherein the polymerizing (a) and the cyclodehydrogenating (b) are performed on an inert surface.

10. A polymeric precursor for the preparation of a graphene nanoribbon, the polymeric precursor comprising repeating units of general formula (II), ##STR00018## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H; unsubstituted C.sub.1-C.sub.40 alkyl residues; and unsubstituted C.sub.1-C.sub.40 alkoxy residues.

11. The polymeric precursor according to claim 10, wherein R.sup.1 and R.sup.2 are each independently selected from the group consisting of H, unsubstituted C.sub.1-C.sub.20 alkyl residues, and unsubstituted C.sub.1-C.sub.20 alkoxy residues; and wherein R.sup.3 and R.sup.4 are H.

12. The polymeric precursor according to claim 10, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are H.

13. A graphene nanoribbon comprising repeating units of general formula (III) ##STR00019## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H; unsubstituted C.sub.1-C.sub.40 alkyl residues; and unsubstituted C.sub.1-C.sub.40 alkoxy residues obtained by the process according to claim 1.

14. The graphene nanoribbon according to claim 13, wherein R.sup.1 and R.sup.2 are each independently selected from the group consisting of H, unsubstituted C.sub.1-C.sub.20 alkyl residues, and unsubstituted C.sub.1-C.sub.20 alkoxy residues; and wherein R.sup.3 and R.sup.4 are H.

15. The graphene nanoribbon according to claim 14, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are H.

16. An electronic, optical, or optoelectronic device comprising the graphene nanoribbon according to claim 13.

17. An electronic, optical or optoelectronic device comprising a thin film semiconductor, the semiconductor comprising the graphene nanoribbon according to claim 13.

18. The electronic, optical or optoclectronic device according to claim 17, wherein the device is at least one selected from the group consisting of an organic field effect transistor device, an organic photovoltaic device, and an organic light-emitting diode.

19. A process for preparing the polymeric precursor comprising repeating units of general formula (II) according to claim 10, the method comprising: polymerizing an ortho-terphenyl of general formula (I) ##STR00020## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H; unsubstituted C.sub.1-C.sub.40 alkyl residues; and unsubstituted C.sub.1-C.sub.40 alkoxy residues; and X and Y are each independently selected from the group consisting of F, Cl, Br, I, and OTf thereby forming the polymeric precursor comprising repeating units of general formula (II).

20. A process for preparing a graphene nanoribbon comprising repeating units of general formula (III), the process comprising: cyclodehydrogenating the polymeric precursor comprising repeating units of general formula (II) according to claim 10 thereby forming a graphene nanoribbon comprising repeating units of general formula (III) ##STR00021## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of H; unsubstituted C.sub.1-C.sub.40 alkyl residues; and unsubstituted alkoxy residues.

Description

EXAMPLES

[0058] FIGS. 1 to 7 show:

[0059] FIG. 1: Synthesis route for 3,6-dibromo-1,1:2,1-terphenyl 8 (ortho-terphenyl (I), wherein R.sup.1R.sup.2R.sup.3R.sup.4H, and XYBr).

[0060] FIG. 2: .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2) of 1,4-dibromo-2,3-diiodobenzene 6.

[0061] FIG. 3: .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2) of 1,4-dibromo-2,3-diiodobenzene 6.

[0062] FIG. 4: .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2) of 3,6-dibromo-1,1:2,1-terphenyl 8.

[0063] FIG. 5: .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2) of 3,6-dibromo-1,1:2,1-terphenyl 8.

[0064] FIG. 6: STM image of the 9-AGNR, obtained from 3,6-dibromo-1,1:2,1-terphenyl 8 after polymerization and cyclodehydrogenation on the Au surface.

[0065] FIG. 7: Magnification showing the superimposition of the STM image with the chemical model of the AGNR structure.

EXAMPLE 1

Preparation of (2,5-dihalophenyl)-2-(hydroxyimino)acetamide 3

[0066] ##STR00010##

[0067] (2,5-Dihalophenyl)-2-(hydroxyimino)acetamide 3 was synthesized as described in S.-J. Garden, J.-C. Torres, A.-A. Ferreira, R.-B. Silva, A.-C. Pinto, Tetrahedron Lett. 1997, 38, 1501. Accordingly, in a 1 L round bottomed flask, 10 g (39.85 mmol) 2,5-dihaloaniline 1, 7.91 g (47.82 mmol) chloralhydrate, 4.15 g (59.78 mmol) hydroxylamine hydrochloride and 48 g sodiumsulfate were placed. 300 mL of ethanol and 300 mL of water were added and the reaction mixture was stirred for 12 h at 80 C. After cooling to room temperature, the precipitate was filtered, washed with a mixture of ethylacetate and hexane (1:10) and dried under vacuum to obtain (2,5-dihalophenyl)-2-(hydroxyimino)acetamide 3 as a white solid in 72% yield.

[0068] .sup.1H-NMR: (300 MHz, DMSO): =12.54 (s, 1H), 9.51 (s, 1H), 8.15 (d, 1H), 7.6 (m, 2H), 7.34 (dd, 1H) ppm.

[0069] .sup.13C-NMR: (300 MHz, DMSO): =160.45, 143.10, 136.73, 134.18, 129.15, 126.50, 120.58, 114.96 ppm.

EXAMPLE 2

Preparation of 4,7-dihaloindoline-2,3-dione 4

[0070] ##STR00011##

[0071] As described in S.-J. Garden et al., Tetrahedron Lett. 1997, 38, 1501, concentrated sulfuric acid (45 mL) was heated to 50 C. in a 250 mL roundbottom flask. Dried (2,5-dihalophenyl)-2-(hydroxyimino)acetamide 3 (5 g, 15.6 mmol) was added and the reaction mixture heated to 100 C. for 30 min. The resulting purple mixture was cooled to room temperature and poured into ice water (300 mL) to precipitate 4,7-dihaloindoline-2,3-dione 4 as light orange solid. The precipitate was filtered and dried in vacuum to obtain 4 in 56% yield.

[0072] .sup.1H-NMR: (300 MHz, DMSO): =11.43 (s, 1H), 7.66 (d, 1H), 7.17 (d, 1H) ppm.

[0073] .sup.13C-NMR: (300 MHz, DMSO): =181.08, 158.94, 151.06, 140.64, 127.86, 118.36, 103.68 ppm.

EXAMPLE 3

Preparation of 2-amino-3,6-dihalobenzoic acid 5

[0074] ##STR00012##

[0075] 2-Amino-3,6-dihalobenzoic acid 5 was synthesized according to a synthesis procedure described in the publication: V. Lisowski, M. Robba, S. Rault, J. Org. Chem. 2000, 65, 4193. Accordingly, 4,7-dihaloindoline-2,3-dione 4 (3 g, 10 mmol) was dissolved in 50 mL 5% sodium hydroxide and heated to 50 C. 30% hydrogen peroxide (50 mL) was added dropwise and the resulting mixture was stirred at 50 C. for an additional 30 min. After cooling to room temperature, the solution was filtered and acidified to pH 4 with 1M hydrochloric acid. The beige precipitate was filtered and dried in vacuum to obtain 2-amino-3,6-dihalobenzoic acid 5 in 65% yield.

[0076] .sup.1H-NMR: (300 MHz, DMSO): =13.73 (b s, 1H), 7.38 (d, 1H), 6.79 (d, 1H), 5.58 (b s, 1H) ppm.

[0077] .sup.13C-NMR: (300 MHz, DMSO): =167.32, 144.12, 134.32, 121.09, 118.96, 107.86 ppm.

EXAMPLE 4

Preparation of 1,4-dibromo-2,3-diiodobenzene 6

[0078] ##STR00013##

[0079] 1,4-dibromo-2,3-diiodobenzene 6 was synthesized according to a procedure published in the article: O. S. Miljanic, K. P. C. Vollhardt, G. D. Whitener Synlett 2003, 29-34. To a stirred and refluxed solution of iodine (2.58 g, 10.17 mmol) and isoamyl nitrite (1.64 mL, 12.21 mmol) in 200 mL 1,2-dichloroethane was added dropwise a solution of 2-amino-3,6-dihalobenzoic acid 5 in 15 mL dioxane. The resulting mixture was refluxed for 1 h, cooled to room temperature, filtered and the filtrate washed with 5% aqueous sodium thiosulfate. The organic phase was dried over magnesium sulfate and the solvent evaporated. The resulting residue was purified by flash column chromatography with hexane to obtain 1,4-dibromo-2,3-diiodobenzene 6 in 60% yield as colourless needles. The spectroscopical data is in agreement with the literature values.

[0080] .sup.1H-NMR: (300 MHz, CD.sub.2Cl.sub.2): =7.45 (s, 2H) ppm.

[0081] .sup.13C-NMR: (300 MHz, CD.sub.2Cl.sub.2): =133.25, 128.09, 117.52 ppm.

EXAMPLE 5

Preparation of 3,6-dibromo-1,1:2,1-terphenyl 8

[0082] ##STR00014##

[0083] 1,4-dibromo-2,3-diiodobenzene 6 (250 mg, 0.5 mmol) and phenylboronic acid (65.63 mg, 0.5 mmol) were dissolved in 10 mL dioxane and 1 mL of 2 M aqueous sodium carbonate was added. Argon was bubbled through the solution for 45 min and, then, tetrakis(triphenylphosphine)palladium(0) (60 mg, 0.1 mol %) was added. Argon was bubbled through the solution for additional 15 min and the reaction mixture stirred at 80 C. for 2 days. After cooling to room temperature, the solution was extracted with water/dichloromethane, the organic phase dried over magnesium sulfate and the solvent evaporated. The crude mixture was purified by column chromatography (PE:DCM 9:1) to obtain the mono coupled product 7 in 60% yield.

[0084] The second iodine was coupled in a similar Suzuki coupling reaction with an additional equivalent of phenylboronic acid. The solution was stirred at 100 C. under Argon for 3 days. The crude reaction mixture was purified by column chromatography (PE:DCM 9:1) to obtain 3,6-dibromo-1,1:2,1-terphenyl 8 in 10% yield. The colorless solid can be recrystallized from ethanol.

[0085] .sup.1H-NMR: (300 MHz, CD.sub.2Cl.sub.2): =7.49 (s, 2H), 7.12-7.05 (m, 6H), 6.93-6.90 (m, 4H) ppm.

[0086] .sup.13C-NMR: (300 MHz, CD.sub.2Cl.sub.2): =144.24, 140.56, 133.14, 130.23, 127.85, 127.45, 123.63 ppm.

[0087] FD-MS: m/z=388.0

EXAMPLE 6

Surface-Assisted Preparation of Graphene Nanoribbons

[0088] The Au(111) single crystal (Surface Preparation Laboratory, Netherlands) was used as the substrate for the growth of N=9 armchair graphene nanoribbons (9-AGNR). First the substrate was cleaned by repeated cycles of argon ion bombardment and annealing to 480 C. and then cooled to room temperature for deposition. 3,6-dibromo-1,1:2,1-terphenyl 8 was deposited onto the clean surface by sublimation at rates of 1 /min. Then the Au(111) substrate was post-annealed at 175 C. for 10 min to induce polymerization and at 400 C. for 10 min to form GNRs. A low temperature STM (LT-STM) from Omicron Nanotechnology GmbH, Germany, was used to characterize the morphology of the 9-AGNR samples. The agreement between model and STM image proves that 9-AGNRs can be synthesized from 3,6-dibromo-1,1:2,1-terphenyl 8 on Au(111) surfaces (FIG. 6).