Polymeric precursors for producing graphene nanoribbons and methods for preparing them

Abstract

An oligophenylene monomer of general formula (I) wherein R.sup.1 and R.sub.2 are independently of each other H, halogene, OH, NH.sub.2, CN, NO.sub.2 or a linear or branched, saturated or unsaturated C.sub.1-C.sub.40 hydrocarbon residue, which can be substituted 1-to 5-fold with halogene (F, Cl, Br, I), OH, NH.sub.2, CN and/or NO.sub.2, and wherein one or more CH.sub.2-groups can be replaced by O or S, or an optionally substituted aryl, alkylaryl or alkoxyaryl residue; and m represents 0, 1 or 2. ##STR00001##

Claims

1. An oligophenylene monomer of general formula (I): ##STR00024## wherein R.sup.1 is a linear or branched C.sub.1-C.sub.30 alkyl and R.sup.2 is H; and m represents 0, 1 or 2.

2. The oligophenylene monomer of claim 1, wherein each R.sup.1 represents a methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, 1,1,3,3-tetramethylpentyl, n-hexyl, 1-methylhexyl, 1,1,3,3,5,5-hexamethylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 1,1,3,3-tetramethylbutyl and 2-ethylhexyl, n-nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl, heneicosyl, docosyl, tetracosyl, or pentacosyl group.

3. The oligophenylene monomer of claim 1, wherein m represents 0.

4. A polymeric precursor for preparing graphene nanoribbons having repeating units of general formula (II): ##STR00025## wherein R.sup.1 is a linear or branched C.sub.1-C.sub.30 alkyl and R.sup.2 is H; m represents 0, 1 or 2; and n represents a number of from 2 to 100.

5. The polymeric precursor of claim 4, wherein each R.sup.1 represents a methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl, 1,1,3,3-tetramethylpentyl, n-hexyl, 1-methylhexyl, 1,1,3,3,5,5-hexamethylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 1,1,3,3-tetramethylbutyl and 2-ethylhexyl, n-nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl, heneicosyl, docosyl, tetracosyl, or pentacosyl group.

6. The polymeric precursor of claim 4, wherein m represents 0.

7. A process for the production of a graphene nanoribbon, comprising: subjecting the polymeric precursor of claim 4 to cyclodehydrogenation.

8. The process of claim 7, wherein the polymeric precursor is prepared by Diels-Alder polymerization of an oligophenylene monomer of general formula (I): ##STR00026## wherein R.sup.1 is a linear or branched C.sub.1-C.sub.30 alkyl and R.sup.2 is H; and m represents 0, 1 or 2.

9. A graphene nanoribbon, comprising cyclodehydrogenated moieties of formula (II): ##STR00027## wherein R.sup.1 is a linear or branched C.sub.1-C.sub.30 alkyl and R.sup.2 is H; m represents 0, 1 or 2; and n represents a number of from 2 to 100.

10. A composition comprising one or more graphene nanoribbons of claim 9 dissolved or dispersed in a liquid medium.

11. An electronic, optical, or optoelectronic device comprising a thin film semiconductor comprising one or more graphene nanoribbons of claim 9.

12. The device of claim 11, wherein the device is an organic field effect transistor device, an organic photovoltaic device, or an organic light-emitting diode.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1: MALDI-TOF MS analysis of a crude product of polymeric precursor IIa (Table 1, entry 1, matrix: TCNQ, linear mode).

(2) FIG. 2: MALDI-TOF MS analysis of a crude product of polymeric precursor IIa (Table 1, entry 1, matrix: TCNQ, reflectron mode).

(3) FIG. 3: Chemical formulae, exact masses and molecular weights of tetrameric, pentameric, hexameric and heptameric polymeric precursor IIa. (Tetramer=C.sub.216H.sub.274, exact mass=2868,14, molecular weight=2870,49; pentamer=C.sub.270H.sub.342, exact mass=3584,68; molecular weight=3587,60; hexamer=C.sub.324H.sub.410, exact mass=4301,21, molecular weight=4304,72; heptamer=C.sub.378H.sub.478, exact mass=5017,74, molecular weight=5021,84)

(4) FIG. 4: Molecular weight distribution of polymeric precursor IIa after fractionation by GPC (Table 1, entry 2, THF, PSS).

(5) FIG. 5: Raman spectrum of graphene nanoribbons IIIa (powder).

(6) FIG. 6: Comparison of UV-VIS absorption spectra: (a) polymeric precursor IIa in THF (14 g/mL) and (b) graphene nanoribbons IIIa as a film on a glass substrate drop-casted from dispersion in THF.

(7) FIG. 7: UV-vis absorption spectrum of graphene nanoribbons IIIa in an exfoliated solution in NMP.

(8) FIG. 8: Output characteristics of graphene nanoribbons IIIa at various gate biases V.sub.G

(9) FIG. 9: Transfer curve of graphene nanoribbons IIIa at a source drain bias of V.sub.SD=60V.

EXAMPLES

Example 1

Preparation of 3-Bromodiphenylacetylene (3)

(10) ##STR00011##

(11) To a degassed solution of 1-bromo-3-iodobenzene 1 (5.03 g, 17.8 mmol) and ethynylbenzene 2 (2.08 g, 20.4 mmol) in a mixture of THF (50 mL) and triethylamine (50 mL) were added copper(I) iodide (52.7 mg, 0.277 mmol) and dichlorobis(triphenylphosphine)palladium(II) (376 mg, 0.536 mmol). After stirring at room temperature for 18 h, the reaction mixture was filtered to remove precipitates. The filtrate was diluted with diethylether, and washed twice with a saturated aqueous solution of ammonium chloride and three times with brine followed by drying over sodium sulfate and concentration in vacuo. Dark brown crude material was purified by silica gel column chromatography (eluent: hexane) to give the title compound as colorless oil (4.46 g, 98% yield).

(12) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 7.25 (t, J=7.9 Hz, 1H), 7.35-7.41 (m, 3H), 7.46-7.57 (m, 4H), 7.70 (t, J=1.7 Hz, 1H).

(13) .sup.13C NMR (75 MHz, CDCl.sub.3): 87.77, 90.65, 122.16, 122.73, 125.30, 128.40, 128.61, 129.76, 130.13, 131.36, 131.66, 134.31.

(14) Elemental Analysis: Calc. for C.sub.14H.sub.9Br: C, 65.40; H, 3.53. Found: C, 65.53; H, 3.65.

Example 2

Preparation of 3-Bromobenzil (4)

(15) ##STR00012##

(16) To a solution of 3-bromodiphenylacetylene 3 (6.38 g, 24.8 mmol) in DMSO (60 mL) was added iodine (3.15 g, 12.4 mmol). The reaction mixture was degassed and stirred at 155 C. for 20 h. After cooling down to room temperature, the reaction was quenched with a saturated aqueous solution of sodium sulfite followed by dilution with dichloromethane. The aqueous layer was extracted three times with dichloromethane and the combined organic layers were washed five times with water. After drying over sodium sulfate and concentration in vacuo purification by silica gel column chromatography (eluent: 30-50% dichloromethane/hexane) yielded the title compound as a yellow solid (4.47 g, 62% yield).

(17) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 7.42 (t, J=7.9 Hz, 1H), 7.51-7.59 (m, 2H), 7.71 (tt, J=1.3, 7.4 Hz, 1H), 7.82 (qd, J=0.99, 8.0 Hz, 1H), 7.89 (td, J=1.2, 7.8 Hz, 1H), 7.93-7.98 (m, 2H), 8.13 (t, J=1.8 Hz, 1H).

(18) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 123.61, 128.99, 129.53, 130.29, 131.10, 132.79, 133.11, 135.16, 135.59, 138.12, 193.42, 194.08.

(19) Elemental Analysis: Calc. for C.sub.14H.sub.9BrO.sub.2: C, 58.16; H, 3.14. Found: C, 58.21; H, 3.32.

Example 3

Preparation of 3-(3-Bromophenyl)-2,5-bis(4-dodecylphenyl)-4-phenyl-2,4-cyclopentadienone (20a)

(20) ##STR00013##

(21) To a solution of 3-bromobenzil 4 (2.00 g, 6.92 mmol) and 1,3-bis(4-dodecylphenyl)-propan-2-one (8a) (3.79 g, 6.93 mmol) in tert-butanol (200 mL) was added at 80 C. an aqueous solution of tetraethylammonium hydroxide (20%, 2.05 mL, 2.77 mmol). After stirring at 80 C. for 50 min the reaction was quenched by the addition of 1 N HCl (40 mL), and the reaction mixture was extracted three times with dichloromethane. The combined organic extracts were washed with water three times, dried over sodium sulfate, and evaporated to give a purple crude product. Purification by silica gel column chromatography (eluent: 20% dichloromethane/hexane) gave the title compound as a purple solid (5.05 g, 91% yield).

(22) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.86-0.90 (m, 6H), 1.23-1.37 (m, 36H), 1.51-1.66 (m, 4H), 2.52-2.62 (m, 4H), 6.87-6.92 (m, 1H), 6.93-6.98 (m, 2H), 7.04-7.16 (m, 10H), 7.18-7.32 (m, 3H), 7.35-7.41 (m, 1H).

(23) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 14.30 (2C), 23.12 (2C), 29.75 (2C), 29.79 (2C), 29.92 (2C), 30.02 (2C), 30.07 (2C), 30.09 (2C), 30.11 (2C), 31.74 (2C), 32.36 (2C), 36.13 (2C), 122.25, 125.64, 126.36, 128.12, 128.46 (2C), 128.48 (2C), 128.60 (2C), 128.90, 129.60 (2C), 129.97, 130.25, 130.34 (2C), 130.35 (2C), 131.61, 132.46, 133.63, 136.13, 143.13, 143.38, 152.58, 152.63, 154.27, 200.93.

(24) Elemental Analysis: Calc. for C.sub.39H.sub.62O: C, 79.57; H, 8.44. Found: C, 79.59; H, 8.56.

Example 4

Preparation of 2,5-Bis(4-dodecylphenyl)-3-phenyl-4-(3-((trimethylsilyl)ethynyl)-phenyl)-2,4-cyclopentadienone (21a)

(25) ##STR00014##

(26) To a degassed suspension of 3-(3-bromophenyl)-2,5-bis(4-dodecylphenyl)-4-phenyl-2,4-cyclopentadienone 20a (3.00 g, 3.75 mmol) and copper(I) iodide (73.5 mg, 0.386 mmol) in triethylamine (200 mL) were added trimethylsilylacetylene (1.60 mL, 11.3 mmol) and tetrakis-(triphenylphosphino)-palladium(0) (438 mg, 0.379 mmol). After stirring at 80 C. for 19 h, the solvent was removed in vacuo. The resulting purple solid was dissolved in dichloromethane and washed once with a saturated aqueous solution of ammonium chloride and then twice with brine. After drying over sodium sulfate and concentration in vacuo, purification by silica gel column chromatography (eluent: 15% dichloromethane/hexane) yielded the title compound as a purple solid (2.10 g, 69% yield).

(27) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.19 (s, 9H), 0.88 (t, J=6.7 Hz, 6H), 1.23-1.36 (m, 36H), 1.55-1.65 (m, 4H), 2.52-2.61 (m, 4H), 6.87-6.92 (m, 1H), 6.92-6.97 (m, 2H), 7.04-7.29 (m, 13H), 7.30-7.35 (m, 1H).

(28) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 0.10 (3C), 14.30 (2C), 23.12 (2C), 29.78 (2C), 29.82 (2C), 29.91 (2C), 30.01 (2C), 30.07 (4C), 30.10 (2C), 31.75 (2C), 32.35 (2C), 36.14 (2C), 95.25, 104.61, 123.49, 125.52, 126.01, 128.27, 128.41 (2C), 128.47 (2C), 128.53 (2C), 128.67, 128.81, 129.61 (2C), 129.82, 130.34 (4C), 130.61, 132.07, 132.50, 133.70, 134.47, 143.07, 143.28, 153.43, 154.43, 154.27, 201.13.

(29) Elemental Analysis: Calc. for C.sub.58H.sub.76OSi: C, 85.23; H, 9.37. Found: C, 84.84; H, 9.33.

Example 5

Preparation of 2,5-Bis(4-dodecylphenyl)-3-(3-ethynylphenyl)-4-phenyl-2,4-cyclopentadienone (Ia)

(30) ##STR00015##

(31) Methanol (100 mL) was added to a suspension of 2,5-bis(4-dodecylphenyl)-3-phenyl-4-(3-((trimethylsilyl)ethynyl)phenyl)-2,4-cyclopentadienone 21a (1.02 g, 1.25 mmol) and potassium fluoride (361 mg, 6.21 mmol) in THF (100 mL), and the reaction mixture was stirred at 40 C. for 5 h. After removal of the solvents at 40 C. in vacuo, purification by silica gel column chromatography (eluent: 15% dichloromethane/hexane) yielded the title compound as a purple solid (786 mg, 84% yield).

(32) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.88 (t, J=6.7 Hz, 6H), 1.23-1.36 (m, 36H), 1.51-1.65 (m, 4H), 2.51-2.61 (m, 4H), 3.04 (s, 1H), 6.91-6.97 (m, 3H), 7.04-7.30 (m, 13H), 7.35-7.39 (m, 1H).

(33) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 14.33 (2C), 23.14 (2C), 29.80 (4C), 29.93 (2C), 30.03 (2C), 30.09 (4C), 30.12 (2C), 31.75 (2C), 32.37 (2C), 36.14 (2C), 77.93, 83.22, 122.35, 125.61, 126.17, 128.25, 128.44 (2C), 128.48 (2C), 128.52, 128.54, 128.56 (2C), 128.84, 129.63 (2C), 130.19, 130.36 (4C), 132.28, 133.00, 133.69, 134.44, 143.08, 143.27, 153.21, 154.34, 201.06.

(34) HRMS (ESI, positive) m/z calc. for C.sub.55H.sub.69O [M+H].sup.+745.5348, found 745.5334.

Example 6

Preparation of Polymeric Precursor (IIa)

(35) ##STR00016##
Method 1: Diels-Alder-Polymerization in a Solution of Diphenyl Ether

(36) A degassed solution of 2,5-bis(4-dodecylphenyl)-3-(3-ethynylphenyl)-4-phenyl-2,4-cyclopentadienone Ia in diphenyl ether was refluxed using a heating mantle. After cooling down to room temperature, diphenyl ether was distilled off and the resulting crude material was fractionated by using recycling gel permeation chromatography (GPC) system (eluent: chloroform).

(37) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.81-0.92 (m, 6H), 1.00-1.68 (m, 40H), 2.15-2.75 (m, 4H), 6.15-7.38 (m, 18H).

(38) Method 2: Diels-Alder-Polymerization in a Neat Condition

(39) A purple powder of 2,5-bis(4-dodecylphenyl)-3-(3-ethynylphenyl)-4-phenyl-2,4-cyclopentadienone Ia in a 25-mL Schlenk tube was heated to 260 C. using a heating mantle. The powder at first melted and then lost its purple color to be pale yellow. After cooling down to room temperature, the resulting polymer was sonicated in THF for 30 min, and the insoluble polymer was filtered off. The filtrate was concentrated in vacuo and fractionated by gel permeation chromatography (eluent: dichloromethane).

(40) TABLE-US-00001 TABLE 1 Reaction conditions and the resulting molecular weights of polymeric precursor IIa entry solvent concentration (mM) time (h) M.sub.w (g/mol).sup.a 1 Ph.sub.2O 36.6 25 .sup.24000 2 Ph.sub.2O 228 28 150000.sup. 3 neat 1.5 350000.sup.b 4 neat 5 620000.sup.b .sup.aGPC analysis of the crude products (THF, PSS, UV detector) .sup.bCrude products were extracted from unsoluble polymer with THF using sonication.

(41) MALDI analysis of a crude product of polymeric precursor IIa (Table 1, entry 1) in reflectron mode showed peaks of tetramer, pentamer, hexamer, heptamer, and octamer at 2869, 3587, 4304, 5021, and 5739, respectively, which indicated that the ethynyl groups and tetraphenylcyclopentadienone moieties at the edges of them was reacted during the reaction (FIG. 2).

Example 7

Preparation of Graphene Nanoribbons (IIIa)

(42) ##STR00017##

(43) A solution of polymeric precursor IIa in non-stabilized dichloromethane was degassed by argon bubbling for 10 min. To the degassed solution was added a suspension of iron(III) chloride in nitromethane. After stirring at room temperature for 3 days under continuous argon bubbling, the reaction was quenched by the addition of methanol to form black precipitates. Filtration by suction using a membrane filter and washing with methanol gave the title compound as black powder.

(44) Although the solubility of graphene nanoribbons IIIa in normal organic solvents was very poor, it was possible to disperse IIIa in THF with the help of sonication. Analysis of the dispersion was not possible because it started to reaggregate immediately after stopping the sonication, but it was possible to make a film of IIIa by drop-casting it on glass substrate and measure solid-state UV-VIS absorption spectrum (FIG. 6b). It was demonstrated that the absorption band is dramatically red shifted upon the cyclodehydrogenation of polymeric precursor IIa (FIG. 6a) to graphene nanoribbons IIIa (FIG. 6b). The spectrum of graphene nanoribbons IIIa showed an absorption peak at 570 nm.

(45) Exfoliation of graphene nanoribbons IIIa was performed in NMP with the help of sonication, which gave UV-VIS absorption spectrum of IIIa from exfoliated solution (FIG. 7). An absorption peak was observed at 550 nm.

(46) Fabrication of OFET devices with graphene nanoribbons IIIa was performed by drop casting the dispersion of IIIa in THF directly after sonication, which demonstrates the field-effect mobility of graphene nanoribbons IIIa to be .sub.max=0.001 cm.sup.2/vs and .sub.avg=0.00087 cm.sup.2/vs in HMDS modified OFET devices (FIGS. 8 and 9).

Example 8

Preparation of 1,3-Bis(4-(2-decyltetradecyl)phenyl)propan-2-one (8b)

(47) ##STR00018##

(48) Dry N,N-dimethylacetamide (10 mL) was added to zinc (3.21 g, 49.1 mmol) and iodine (0.689 mg, 2.71 mmol) in a 100-mL two-necked flask equipped with a condenser, and stirred at room temperature until the purple color of iodine disappeared. 2-decyl-tetradecylbromide (15.3 g, 36.7 mmol) was then added to the mixture and stirred at 80 C. for 24 h to generate dodecylzinc bromide. To 1,3-bis(4-bromophenyl)-propan-2-one 7b (2.00 g, 5.43 mmol) and dichloro[1,1-bis(diphenylphosphino)-ferrocene]palladium(II) (0.384 g, 0.544 mmol) in a 100-mL Schlenk flask was added via cannula the solution of dodecylzinc bromide. The reaction mixture was stirred at room temperature for 18 h, and then quenched by hydrochloric acid (2 M, 40 mL). The aqueous layer was extracted three times with dichloromethane. The combined organic extracts were washed three times with water, dried over sodium sulfate, and evaporated. The crude material was purified by silica gel column chromatography (eluent: 20% dichloromethane/hexane) to give the title compound as pale yellow oil (4.13 g, 86% yield).

(49) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2) : 0.88 (t, J=6.7 Hz, 12H), 1.16-1.37 (m, 80H), 1.55-1.67 (m, 2H), 2.50 (d, J=7.0 Hz, 4H), 3.68 (s, 4H), 7.01 (d, J=8.1 Hz, 4H), 7.09 (d, J=8.1 Hz, 4H).

(50) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 14.36 (4C), 23.18 (4C), 26.99 (4C), 29.85 (4C), 30.16 (16C), 30.50 (4C), 32.42 (4C), 33.60 (4C), 40.12 (2C), 40.57 (2C), 49.13 (2C), 129.70 (4C), 129.86 (4C), 131.88 (2C), 141.11 (2C), 206.30.

(51) Elemental Analysis: Calc. for C.sub.63H.sub.110O: C, 85.64; H, 12.55. Found: C, 85.71; H, 12.45.

Example 9

Preparation of 3-(3-Bromophenyl)-2,5-bis(4-(2-decyltetradecyl)phenyl)-4-phenyl-2,4-cyclopentadienone (20b)

(52) ##STR00019##

(53) To a solution of 3-bromobenzil 4 (0.808 g, 2.79 mmol) and 1,3-bis(4-(2-decyltetradecyl)phenyl)propan-2-one 8b (2.55 g, 2.89 mmol) in tert-butanol (70 mL) was added at 80 C. an aqueous solution of tetraethylammonium hydroxide (20%, 0.82 mL, 1.12 mmol). After stirring at 80 C. for 40 min, the reaction was quenched by the addition of hydrochloric acid (2 M, 20 mL), and the reaction mixture was concentrated in vacuo and then extracted twice with dichloromethane. The combined organic extracts were washed twice with water, dried over sodium sulfate, and evaporated. Purification by silica gel column chromatography (eluent: 10% dichloromethane/hexane) gave the title compound as a purple oil (2.71 g, 85% yield).

(54) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.88 (t, J=6.7 Hz, 12H), 1.15-1.35 (m, 80H), 1.55-1.67 (m, 2H), 2.50 (t, J=6.4 Hz, 4H), 6.87 (td, J=1.1, 7.9 Hz, 1H), 6.92-6.98 (m, 2H), 7.01-7.16 (m, 10H), 7.18-7.32 (m, 3H), 7.35-7.41 (m, 1H).

(55) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 14.33 (4C), 23.15 (4C), 26.96 (4C), 29.82 (4C), 30.12 (16C), 30.44 (4C), 32.39 (4C), 33.61 (2C), 33.64 (2C), 40.01 (2C), 40.78 (2C), 122.26, 125.69, 126.42, 128.09, 128.42, 128.47 (2C), 128.49, 128.91, 129.30 (2C), 129.41 (2C), 129.65 (2C), 129.93, 130.20 (4C), 131.62, 132.56, 133.66, 136.13, 142.12, 142.39, 152.55, 154.22, 200.95.

(56) HRMS (ESI, positive) m/z calc. for C.sub.77H.sub.116OBr [M+H].sup.+1135.8210, found 1135.8199.

Example 10

Preparation of 2,5-Bis(4-(2-decyltetradecyl)phenyl)-3-phenyl-4-(3-((trimethylsilyl)-ethynyl)phenyl-2,4-cyclopentadienone (21b)

(57) ##STR00020##

(58) To a degassed suspension of 3-(3-bromophenyl)-2,5-bis(4-(2-decyltetradecyl)phenyl)-4-phenyl-2,4-cyclopentadienone 20b (1.53 g, 1.34 mmol) and copper(I) iodide (30.0 mg, 0.158 mmol) in triethylamine (100 mL) were added trimethylsilylacetylene (0.580 mL, 4.07 mmol) and tetrakis-(triphenylphosphino)-palladium(0) (158 mg, 0.137 mmol). After stirring at 80 C. for 16 h, the solvent was removed in vacuo. Purification by silica gel column chromatography (eluent: 10% dichloromethane/hexane) yielded the title compound as a purple oil (1.23 g, 79% yield).

(59) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.19 (s, 9H), 0.88 (t, J=6.8 Hz, 12H), 1.16-1.36 (m, 80H), 1.53-1.66 (m, 2H), 2.45-2.53 (m, 4H), 6.85-6.97 (m, 3H), 7.00-7.29 (m, 13H), 7.30-7.35 (m, 1H).

(60) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 0.05 (3C), 14.35 (4C), 23.16 (4C), 26.93 (2C), 26.97 (2C), 29.83 (4C), 30.13 (16C), 30.44 (4C), 32.40 (4C), 33.60 (2C), 33.66 (2C), 39.95, 40.02, 40.71, 40.80, 95.23, 104.66, 123.55, 125.55, 126.02, 128.25, 128.41 (2C), 128.49, 128.52, 128.83, 129.30 (2C), 129.37 (2C), 129.68 (2C), 129.85, 130.21 (4C), 132.10, 132.55, 133.75, 134.55, 142.07, 142.24, 153.42, 154.43, 201.17.

(61) HRMS (ESI, positive) m/z calc. for C.sub.83H.sub.124ONaSi [M+Na].sup.+1175.9319, found 1175.9371.

Example 11

Preparation of 2,5-Bis(4-(2-decyltetradecyl)phenyl)-3-(3-ethynylphenyl)-4-phenyl-2,4-cyclopentadienone (Ib)

(62) ##STR00021##

(63) Methanol (15 mL) was added to a suspension of 2,5-bis(4-(2-decyltetradecyl)phenyl)-3-phenyl-4-(3-((trimethylsilyl)ethynyl)phenyl-2,4-cyclopentadienone 21b (110 mg, 0.0953 mmol) and potassium fluoride (54.5 mg, 0.938 mmol) in THF (15 mL), and the reaction mixture was stirred at 40 C. for 21 h. After removal of the solvent at 40 C. in vacuo, purification by silica gel column chromatography (eluent: 6-10% dichloromethane/hexane) yielded the title compound as a purple oil (93.8 mg, 91% yield).

(64) .sup.1H NMR (300 MHz, CD.sub.2Cl.sub.2): 0.88 (t, J=6.8 Hz, 12H), 1.18-1.34 (m, 80H), 1.54-1.67 (m, 2H), 2.46-2.54 (m, 4H), 3.03 (s, 1H), 6.90-6.97 (m, 3H), 7.01-7.30 (m, 13H), 7.34-7.39 (m, 1H).

(65) .sup.13C NMR (75 MHz, CD.sub.2Cl.sub.2): 14.32 (4C), 23.13 (4C), 26.93 (4C), 29.80 (4C), 30.10 (16C), 30.41 (4C), 32.37 (4C), 33.58 (2C), 33.62 (2C), 39.98 (2C), 40.75 (2C), 77.87, 83.20, 122.34, 125.63, 126.19, 128.19, 128.40 (2C), 128.46, 128.50, 128.83, 129.28 (2C), 129.36 (2C), 129.66 (2C), 130.19 (5C), 132.26, 133.06, 133.69, 134.43, 142.07, 142.25, 153.18, 154.29, 201.09.

(66) MS (MALDI-TOF) m/z (%) calc. for C.sub.79H.sub.116O 1081 (43), 1082 (37), 1083 (16), 1084 (4). found 1081 (34), 1082 (38), 1083 (21), 1084 (7).

Example 12

Preparation of Polymeric Precursor (IIb)

(67) ##STR00022##

(68) A degassed solution of 2,5-bis(4-(2-decyltetradecyl)phenyl)-3-(3-ethynylphenyl)-4-phenyl-2,4-cyclopentadienone (Ib) in a 25-mL Schlenk tube was heated to 260 C. using a heating mantle. The powder at first melted and then lost its purple color to be pale yellow. After cooling down to room temperature the resulting polymer was sonicated in THF for 30 min, and the insoluble polymer was filtered off. The filtrate was concentrated in vacuo and fractionated by gel permeation chromatography (eluent: dichloromethane).

Example 13

Preparation of Graphene Nanoribbons (IIIb)

(69) ##STR00023##

(70) A solution of polymeric precursor IIb in unstabilized dichloromethane was degassed by argon bubbling for 10 min. To the degassed solution was added a suspension of iron(III) chloride in nitromethane. After stirring at room temperature for 3 days under continuous argon bubbling, the reaction was quenched by the addition of methanol to form black precipitates. Filtration by suction using a membrane filter and washing with methanol gave the title compound as black powder.