Graphene nanoribbons with controlled zig-zag edge and cove edge configuration

Abstract

Provided are graphene nanoribbons with controlled zig-zag edge and cove edge configuration and methods for preparing such graphene nanoribbons. The nanoribbons are selected from the following formulae. ##STR00001##

Claims

1. A graphene nanoribbon, represented by structure (i), structure (ii), structure (iii), structure (iv), structure (v), structure (vi), structure (vii), structure (viii), or structure (ix): ##STR00049## ##STR00050## ##STR00051## ##STR00052## wherein: X independently from each other, are a leaving group, hydrogen, or a free radical; R.sup.b independently from each other are hydrogen, a linear C.sub.1-C.sub.30 alkyl, a branched C.sub.1-C.sub.30, alkyl, OR.sub.3 or NR.sub.1R.sub.2; wherein: R.sub.1 and R.sub.2 are, independently of each other, hydrogen, a linear C.sub.1-C.sub.6alkyl, a branched C.sub.1-C.sub.6alkyl, or phenyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are bonded form a group represented by ##STR00053## and R.sub.3 is selected from hydrogen, C.sub.1-C.sub.30 alkyl and phenyl, which may be unsubstituted or substituted by one or more C.sub.1-C.sub.4 alkyl, phenyl, halogen, C.sub.1-C.sub.4 alkoxy or C.sub.1-C.sub.4 alkylthiol; or R.sup.b is alpha-hydrogen substituted aryl that may form a 5-membered carbocyclic ring with a neighboring hydrogen substituted edge carbon by cycloannelation; or one of two direct neighboring groups R.sup.b is an alpha-hydrogen substituted aryl and the other is hydrogen, and the two carbon atoms substituted with hydrogen may form a 5-membered carbocyclic ring by cycloannelation, R.sup.c independently of each other, are hydrogen or C.sub.1-C.sub.10 alkyl; or two neighboring groups R.sup.c are hydrogen, and the two carbon atoms substituted with hydrogen may form a 5-membered carbocyclic ring by cycloannelation; and n is an integer of from 2 to 2500.

2. The graphene nanoribbon according to claim 1, represented by structure (i).

3. The graphene nanoribbon according to claim 1, represented by structure (ii).

4. The graphene nanoribbon according to claim 1, represented by structure (iii).

5. The graphene nanoribbon according to claim 1, represented by structure (iv).

6. The graphene nanoribbon according to claim 1, represented by structure (vi).

7. The graphene nanoribbon according to claim 1, represented by structure (vii).

8. The graphene nanoribbon according to claim 1, represented by structure (viii).

9. The graphene nanoribbon according to claim 1, represented by structure (ix).

10. A process for preparing the graphene nanoribbon according to claim 1, the process comprising: (a) providing at least one aromatic monomer compound, which is at least one substituted or unsubstituted polycyclic aromatic monomer compound, at least one substituted or unsubstituted oligo phenylene aromatic monomer compound, or any combination thereof, on a solid substrate; (b) polymerizing of the aromatic monomer compound so as to form at least one polymer on the surface of the solid substrate; and (c) at least partially cyclodehydrogenating the one or more polymers of said (b) polymerization to obtain the graphene nanoribbon having structure (i), structure (ii), structure (iii), structure (iv), structure (v), structure (vi), structure (vii), structure (viii), or structure (ix).

11. A process for preparing the graphene nanoribbon according to claim 1, the process comprising: (a) providing at least one aromatic monomer compound which is at least one substituted or unsubstituted polycyclic aromatic monomer compound, at least one substituted or unsubstituted oligo phenylene aromatic monomer compound, or any combination thereof, in solution; (b) polymerizing of the aromatic monomer compound so as to form at least one polymer; and (c) at least partially cyclodehydrogenating the one or more polymers of said (b) polymerization to obtain the graphene nanoribbon having structure (i), structure (ii), structure (iii), structure (iv), structure (v), structure (vi), structure (vii), structure (viii), or structure (ix).

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1a shows a high resolution STM image of the terminus of a N=5 cove-edge zigzag GNR structure iii obtained after deposition of the precursor monomer 6 on Au (111) and subsequent polymerization and cyclodehydrogenation (U=0.9V, I=0.4 nA).

(2) FIG. 1b shows the same STM image as shown in FIG. 1a with a chemical model superimposed.

(3) FIG. 2a shows an STM image (U=1 V, I=0.03 nA) obtained after deposition of the precursor monomer 2 and polymerization

(4) FIG. 2b shows an STM image (U=1V, I=0.03 nA) of the final GNR structure vi after cyclodehydrogenation

(5) FIG. 3a shows an STM image (U=1 V, I=0.02 nA) obtained after deposition of the precursor monomer 3 and polymerization

(6) FIG. 3b shows an STM image (U=1V, I=0.02 nA) of the final GNR structure vii after cyclodehydrogenation

(7) FIG. 4a shows STM image (c, U=1 V, 1=0.06 nA) obtained after deposition of the precursor monomer 1 and polymerization

(8) FIG. 4b shows an STM image (U=2.9 V, 1=0.1 nA) of the final GNR structure v after cyclodehydrogenation

(9) FIG. 5 shows the method for defining the width N of (a) zig-zag-type, (b) cove-type, and (c) armchair-type GNR as used herein and illustrates the A and B sublattices of the GNR.

(10) FIG. 6a shows an STM image of GNR structure i fabricated on a Au (111) surface from monomer 9 (U=1.0 V, 1=0.03 nA).

(11) FIG. 6b shows the same STM image as shown in FIG. 6a with a chemical model of the GNR structure superimposed.

(12) The following examples shall further illustrate the present invention without restricting the scope of this invention.

EXAMPLES

1. Synthesis Scheme of Monomer 1 (Monomer Structure V)

(13) ##STR00028##

7-Bromo-2-Naphthol (101)

(14) To a stirring suspension of Triphenyl phosphine (31.5 g) in Acetonitrile (50 mL) in a 250 mL-Schlenk-flask was added carefully Bromine (6.2 mL) at 0 C. with a syringe over 30 min. The yellow solution was warmed to room temperature and 2,7-Dihydroxynaphthalene (16 g) was added in one portion. The reaction was refluxed at 70 C. for one hour. After cooling to room temperature, the solvent was removed under reduced pressure. The reaction flask was connected to a gas-washing bottle filled with a concentrated sodium hydroxide solution. The flask was heated to 250 C. for two hours and the black residue dissolved in 100 mL Dichloromethane and purified via column chromatography (DCM:Pentan 1:1 to pure DCM). Product 101 was received as a beige powder (14.7 g, 66%)

(15) DC: Dichloromethane:Pentane, 1:1, R.sub.f=0.2

(16) .sup.1H-NMR: (300 MHz, CDCl.sub.3)=7.76 (d, 1H), 7.63 (d, 1H), 7.54 (d, 1H), 7.32 (dd, 1H), 7.03 (dd, 1H), 6.98 (d, 1H), 4.98 (b, 1H)

3,5-Dimethylbiphenyl-4-carbaldehyde (102)

(17) p-Bromo-benzaldehyde (2.65 g) and 3,5-Dimethylphenyl boronic acid were added to a 250 mL-flask. After that, the solids were dissolved in THF (100 mL), Ethanol (60 mL) and 2M sodium carbonate solution (50 mL) and Argon bubbled through the solution for one hour. 10 mol % Tetrakistriphenyl-Palladium(0) (1 g) were added and the reaction mixture refluxed for 16 hours. The red solution was cooled to room temperature, extracted with 300 mL of Ethylacetate and washed with water. The organic phase was dried over MgSO.sub.4 and the solvents removed under reduced pressure. The black residue was dissolved and purified via column chromatography (EA:Hexane, 1:10). The product 102 was collected as a yellow oil (1.8 g, 60%)

(18) TLC: Ethylacetate:Hexane, 1:10, R.sub.f=0.7

(19) .sup.1H-NMR: (300 MHz, CD.sub.2Cl.sub.2)=9.95 (s, 1H), 7.85 (d, 2H), 7.68 (d, 2H), 7.20 (s, 2H), 6.99 (s, 1H), 2.31 (s, 6H)

2,12-Dibromo-14-(3,5-dimethylbiphenyl-4-yl)-14H-dibenzo[a,j]-Xanthene (103)

(20) Bromonaphthol 101 (2.7 g) and 3,5-Dimethylbiphenyl-4-Carbaldehyde 102 (1.27 g) were added together with p-Toluenesulfonic acid (25 mg) in a microwave reactor and heated to 130 C. under stirring. After 4 h at this temperature, the reaction mixture was cooled to room temperature and washed with a mixture of water and ethanol (3:1). The red solid was recrystallized from ethanol and the white powder filtered and washed with cold ethanol to give product 103 (2.62 g, 70%).

(21) TLC: Ethylacetate:Hexane, 1:10, R.sub.f=0.4

(22) .sup.1H-NMR: (500 MHz, C.sub.2D.sub.2Cl.sub.4)=8.47 (s, 2H), 7.71 (d, 2H), 7.63 (d, 2H), 7.45-7.43 (m, 6H), 7.33 (d, 2H), 6.96 (s, 2H), 6.84 (s, 1H), 6.19 (s, 1H), 2.21 (s, 6H)

(23) .sup.13C-NMR: (500 MHz, C.sub.2D.sub.2Cl.sub.4)=149.19; 143.05; 140.12; 139.74; 138.29; 132.54; 130.57; 129.51; 129.16; 128.42; 127.93; 127.63; 125.22; 125.03; 121.68; 118.67; 116.12; 37.72; 21.48

(24) FD-MS: m/z=619.9

2,12-Dibromo-14-(3,5-dimethyl-[1,1-biphenyl]-4-yl)-14H-dibenzo[a,j]xanthene-14-ol (104)

(25) The Xanthene 103 (2.5 g) was suspended together with lead (IV)oxide (7.71 g) in 50 mL acetic acid and stirred for 2 days at 130 C. The mixture was cooled to room temperature and poured on 300 mL water. The brown solid was filtered and recrystallized from a mixture of water and acetone (1:1). The product 104 is collected as a beige powder, which could not be purified. The crude product was used in the next step.

(26) TLC: Ethylacetate:Hexane, 1:10, R.sub.f=0.2

2,12-Dibromo-14-(3,5-dimethylbiphenyl-4-yl)-dibenzo[a,j]-Xanthenium-Tetrafluoroborate (105)

(27) The Xanthenol 104 (2.00 g) was dissolved in Toluene (5 mL) and acetic acid anhydride (15 mL) and the solution cooled to 0 C. Tetrafluoroboric acid (50 w %, 1.2 mL) was added carefully to precipitate the red product. It was stirred for 1 h and the product filtered and washed with 100 mL cold diethylether and a 2:1-mixture of petroleum ether and dichloromethane to yield 105 (1.58 g, 65%).

(28) .sup.1H-NMR: (500 MHz, C.sub.2D.sub.2Cl.sub.4)=8.73 (d, 2H), 8.24 (d, 2H), 8.11 (d, 2H), 8.00 (d, 2H), 7.86 (d, 2H), 7.55 (d, 2H), 7.44 (s, 2H), 7.38 (s, 2H), 7.12 (s, 1H), 2.42 (s, 6H)

2,12-Dibromo-14-(3,5-dimethyl-[1,1-biphenyl]-4-yl)-7-phenyl-benzo[m]tetraphene (1)

(29) The Xanthenium-Tetrafluoroborate 105 (1 g) was suspended together with sodium-2-phenylacetate (900 mg) in 12 mL acetic acid anhydride. It was stirred for 5 h at 155 C. and the solvent removed under reduced pressure. The brown residue was dissolved in Dichlormethane and purified via column chromatography (DCM:PE, 1:4). The yellow product 1 was recrystallized from chloroform (314 mg, 32%).

(30) DC: Dichloromethane:Petroleum ether, 1:4, R.sub.f=0.6

(31) .sup.1H-NMR: (500 MHz, CD.sub.2Cl.sub.4)=7.83 (d, 2H), 7.58-7.39 (m, 19H), 7.04 (s, 1H), 2.40 (s, 6H)

(32) .sup.13C-NMR: (500 MHz, CD.sub.2Cl.sub.4)=142.85; 142.48; 141.34; 139.01; 138.51; 137.96; 137.57; 132.78; 132.28; 132.18; 131.88; 131.37; 130.47; 129.91; 129.29; 129.22; 128.70; 127.97; 127.14; 127.03; 125.98; 125.80; 120.36; 118.75; 21.66

2. Synthesis of Monomers 2, 3 and Intermediate 115 (Monomer Structures VI, VII)

(33) ##STR00029##

2,12-dibromo-14-phenyl-14H-dibenzo[a,j]xanthene (107)

(34) To a mixture of benzaldehyde (1 mmol) and bromo-naphthol 101 (2 mmol), p-TSA (0.02 mmol) was added. The reaction mixture was stirred magnetically at 125 C. for about 24 h and the reaction followed by TLC. After completion of the reaction, the mixture was washed with EtOHH.sub.2O (1:3). The crude product was purified by recrystallization from EtOH to give target compound 107. White needles (yield=86%)

14-([1,1-biphenyl]-4-yl)-2,12-dibromo-14H-dibenzo[a,j]xanthene (108)

(35) Compound 108 was prepared in analogy to 107 from p-phenyl-benzaldehyde and bromonaphthol 101. White needles (yield=83%)

2,12-dibromo-14-phenyl-14H-dibenzo[a,j]xanthen-14-ol (109)

(36) Compound 107 (5 mmol) and lead dioxide (PbO.sub.2; 7.5 mmol) in glacial acetic acid (50 ml) were stirred while heating on an oil bath at 120 C. for 12 h. The cooled mixture was poured onto crushed ice and the solid residue was recrystallized from aqueous acetone to give 109. White powder (yield=75%)

14-([1,1-biphenyl]-4-yl)-2,12-dibromo-14H-dibenzo[a,j]xanthen-14-ol (110)

(37) Compound 110 was prepared in analogy to compound 109 from compound 108. White powder (yield=71%)

2,12-dibromo-14-phenyldibenzo[a,j]xanthenylium tetrafluoroborate (111)

(38) Compound 109 (5 mmol) in acetic anhydride (15 ml) and toluene (10 ml) were cooled to 0 C. and treated with terafluoroboric acid (ca. 25 mmol) until no further precipitation occurred. The cooled solution was filtered and washed with anhydrous ether to yield 111 as product. Orange red powder (yield=90%)

14-([1,1-biphenyl]-4-yl)-2,12-dibromodibenzo[a,j]xanthenylium tetrafluoroborate (112)

(39) Compound 112 was prepared in analogy to compound 111 from compound 110. Orange red powder (yield=92%)

2,12-dibromo-7,14-diphenylbenzo[m]tetraphene (2)

(40) A mixture of pyrylium salt 111 (3 mmol) and sodium 2-phenylacetate (9 mmol) in acetic anhydride (Ac.sub.2O 50 ml) was stirred at 150 C. for 12 h under argon atmosphere. After cooling to room temperature, the precipitate was filtered off and washed with Ac.sub.2O, then methanol. The crude product was recrystallized from chloroform and hexane to give monomer 2. Gray powder (yield=34%)

(41) 1H NMR (300 MHz, CDCl3) ppm 7.71 (dd, J=7.78 Hz, 4H), 7.79-7.37 (m, 5H), 7.55-7.36 (m, 11H)

(42) FD-MS: m/z=589.1

14-([1,1-biphenyl]-4-yl)-2,12-dibromo-7-phenylbenzo[m]tetraphene (3)

(43) Monomer 3 was prepared in analogy to monomer 2 from compound 112. Gray powder (yield=32%)

(44) .sup.1H NMR (500 MHz, 1,1,2,2-tetrachloroethane-d2, 403K) ppm 7.77 (d, J=7.85 Hz, 2H), 7.71 (d, J=7.22 Hz, 2H), 7.55 (s, 2H), 7.49 (d, J=8.68 Hz, 4H), 7.46-7.34 (m, 12H), 7.31 (t, J=7.27, 1H)

(45) FD-MS: m/z=665.7

2,12-dibromo-7-(4-iodophenyl)-14-phenylbenzo[m]tetraphene (115)

(46) The compound 115 was prepared in analogy to monomer 1 from compound 111 and sodium 2-(p-iodophenyl)acetate. Brown powder (yield=34%)

(47) .sup.1H NMR (300 MHz, CDCl.sub.3) ppm 7.95 (d, J=8.3 Hz, 2H), 7.8-7.65 (m, 3H), 7.63 (s, 1H), 7.60 (s, 1H), 7.55-7.36 (m, 10H), 7.2 (d, J=8.37 Hz, 2H)

(48) FD-MS: m/z=714.3

3. Synthesis of Monomer 4 (Monomer Structure VI)

(49) ##STR00030##

1-bromo-2-decyl-tetradecane (116)

(50) 2-decyltetradecan-1-ol (30 g, 84.5 mmol) and triphenylphosphine (45 g, 169 mmol) were dissolved in dichloromethane (100 ml) and cooled to 0 C. To the mixture N-bromosuccinimide (23 g, 127 mmol) was added slowly, then stirred at room temperature for 24 hours. After evaporation of solvents in vacuo the products were dissolved in hexane. Purification by column chromatography (silica gel, hexane) yielded compound 116. Colorless oil (yield=97%).

4-decyl-hexadec-1-yne (117)

(51) To a suspension of a lithium acetylide-ethylenediamine complex (40 mmol) in DMSO (30 ml) was added compound 116 (10 mmol) at 0 C. The reaction mixture was stirred for 12 h at room temperature (23 C.). Then sat. aq. NH.sub.4Cl (20 ml) was added to the mixture. The mixture was extracted with ether, washed with brine, dried over MgSO.sub.4, and concentrated. The residue was chromatographed over silica gel (hexane) to afford 117. Colorless oil (yield=99%).

(52) ##STR00031##

2,12-dibromo-7-(4-(4-decyl-hexadecyl)phenyl)-14-phenylbenzo[m]tetraphene (4)

(53) To a mixture of compound 115 (0.6 mmol) and PdCl.sub.2(PPh.sub.3).sub.2 (0.03 mmol) in THF (50 ml), compound 117 (0.9 mmol) and CuI (0.06 mmol) was added. The mixture was bubbled with argon for 20 min and then stirred for 24 h at room temperature. The reaction was monitored by TLC. After the reaction was completed, the mixture was extracted with ethyl acetate, washed with brine, dried over MgSO.sub.4, and concentrated. The residue was passed through a short pad of silca gel (AcOEt) to afford the crude Sonogashira coupling product.

(54) The crude product was dissolved in 50 ml dry THF and Palladium on active carbon (Pd/C, 10%) was added. The mixture was stirred in an autoclave under hydrogen (H.sub.2) atmosphere (5 bar) at r.t. for 12 h. The reaction mixture was filtered and the solution concentrated under vacuum. The residue was chromatographed over silica gel (hexane/AcOEt=10/1) to afford compound 4. Light yellow powder (yield=88%).

(55) 1H NMR (300 MHz, CDCl3) ppm 7.8-7.364 (m, 3H), 7.61 (s, 1H), 7.58 (s, 2H), 7.51-7.38 (m, 11H), 7.37-7.31 (m, 2H), 2.77 (t, J=7.66 Hz), 1.81 (m, 2H), 1.41 (m, 1H), 1.37-0.97 (d, J=10.87, 42H), 0.88 (m, 6H)

(56) FD-MS: m/z=953.4

(57) ##STR00032##

Polymerization of Monomer 4 to Yield Polymer 119

(58) Bis(1,5-cyclooctadiene)nickel (0) (23 mg, 0.084 mmol), 1,5-cyclooctadiene (0.01 ml, 0.084 mmol), and 2,2-bipyridine (13 mg, 0.084 mmol) in dry DMF (4 ml) was charged under argon in a microwave tube equipped with magnetic stirrer bar and heated at 80 C. for 30 min.

(59) A solution of monomer 4 (20 mg, 0.02 mmol) in dry toluene (4 ml) was added. The mixture was vigorously stirred in a CEM Discover microwave reactor at 300 W and active cooling, keeping the temperature at 110 C. for 12 hours. After the reaction was completed, the mixture was poured into a mixture of methanol and concentrated HCl (1:1, 20 ml), and stirred for 4 h. The precipitated yellow polymer 119 was filtered off and dried under vacuum at 80 C. overnight. Yellow powder (yield=85%)

(60) Polymer 119 is transformed into the corresponding GNR by cyclodehyrogenation reaction in solution as described in WO2013/061258.

4. Synthesis of Monomer 5 (Monomer Structure IV)

(61) ##STR00033## ##STR00034## ##STR00035##

3-Bromo-4-iodoanisole (120)

(62) A stirred solution of 3-bromoanisole (10 g, 53.5 mmol), HgO (8.8 g, 40.6 mmol), Ac.sub.2O (1 mL) in CH.sub.2Cl.sub.2 (100 mL) was refluxed for 30 min. Then, I.sub.2 (17.6 g, 69.5 mmol) was added by 6 portions every 30 min. After refluxing for 12 h and filtration over a pad of celite, the filtrate was washed with a saturated Na.sub.2S.sub.2O.sub.3 solution. The aqueous layer was extracted with CH.sub.2Cl.sub.2 (310 mL) and the combined organic layers were dried with MgSO.sub.4 and evaporated to dryness. Purification by flash chromatography (cyclohexane) afforded the titled compound.

(63) Colorless oil (yield=94%).

(64) .sup.1H NMR (300 MHz, CDCl3) ppm 7.68 (d, J=8.8 Hz, 1H), 7.19 (d, J=2.8 Hz, 1H), 6.59 (dd, J=2.8 Hz, J=8.8 Hz, 1H), 3.77 (s, 3H).

((2-Bromo-4-methoxyphenyl)ethynyl)triisopropylsilane (121)

(65) To a mixture of aryl iodide 120 (10 g, 32 mmol), PdCl.sub.2(PPh.sub.3)2 (448 mg, 0.64 mmol), CuI (243.4 mg, 1.28 mmol), TEA (14 mL) in THF (100 mL) was added dropwise under an argon atmosphere a solution of (Triisopropylsilyl)acetylene (8.74 g, 48 mmol). The mixture was stirred at room temperature overnight. Then Et.sub.2O (20 mL) was added to the crude and the mixture was filtered over a short pad of celite. The organic layer was washed with brine (5 mL) twice, separated, dried over MgSO.sub.4, filtered, and concentrated. Purification by flash chromatography afforded alkyne 121. Colorless oil (yield=93%)

Triisopropyl((4-methoxy-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethynyl)silane (122)

(66) A 250 ml round flask was charged with alkyne 121 (19.5 g, 53.1 mmol), Bis(pinacolato)diboron (14.8 g, 58.4 mmol), KOAc (15.6 g, 159 mmol) and PdCl.sub.2(dppf) (1.2 g, 1.6 mmol), then the stirring mixture was purged by Argon for 20 min. After the mixture was stirred overnight at 80 C. under an argon atmosphere, the mixture was extracted with ethyl acetate (20 ml3). The combined organic layer was dried over MgSO.sub.4, filtered and concentrated. The crude residue was purified by pass through a short pad of silica gel to remove the catalyst and used directly for the next step. Brown yellow oil (Yield=85%)

(3,5-Dimethyl-[1,1-biphenyl]-4-yl)trimethylsilane (123)

(67) A 250 ml round flask was charged with 1-bromo-3,5-dimethylbenzene (6 g, 32.4 mmol), (4-(trimethylsilyl)phenyl)boronic acid (9.44 g, 48.6 mmol), K.sub.2CO.sub.3 solution (18 g in 10 ml water), ethanol 10 ml, toluene 50 ml. The mixture was bubbled with argon for 10 min, then Pd(PPh.sub.3)4 (1.87 g, 1.62 mmol) was added. The resulting mixture was treated with liquid nitrogen bath. After three times freeze-pump-thaw procedure, the mixture was refluxed overnight. The reaction was monitored by TLC. After the reaction finished, the mixture was washed with deionized water and the water layer was extracted with ethyl acetate (10 ml2). The combined organic layer was dried over MgSO.sub.4, filtered and concentrated. The crude product was purified by chromatography to afford compound 123. Colorless oil (yield=95%)

(3,5-Dimethyl-[1,1-biphenyl]-4-yl)boronic acid (124)

(68) Compound 123 (8 g, 31.4 mmol) was treated with neat boron tribromide (12.6 g, 50.3 mmol) under argon. A condenser was attached that was also charged with argon, and the solution was heated to 100 C. for 4 h. Once cooled, excess boron tribromide was distilled off under vacuum at room temperature. The resulting gray-purple solid was dissolved in dry hexane (50 ml) and cooled to 0 C. with an ice bath. Water was slowly added dropwise while stirring vigorously until the reaction had been fully quenched. The resulting mixture was filtered and the white solid was washed with deionized water and hexane. The white powder was dried at 80 C. under vacuum overnight, yielding boronic acid 124. White powder (yield=98%)

1,3-Dibromo-2-iodobenzene (125)

(69) At 75 C., butyllithium (42.4 mmol) in hexanes (50 mL) and diisopropylamine (42.4 mmol) were added successively to tetrahydrofuran (20 mL). After 15 min 1,3-dibromobenzene (5.12 mL, 10 g, 42.4 mmol) was added. The mixture was kept for 2 h at 75 C. before a solution of iodine (10.76 g, 42.4 mmol) in tetrahydrofuran (50 mL) was added. After addition of a 10% aqueous solution (0.10 L) of sodium thiosulfate, the mixture was extracted with diethyl ether (310 mL). The combined organic layers were dried over sodium sulfate before being evaporated to dryness. Upon crystallization from ethanol (100 mL), colorless platelets were obtained. Colorless platelets (yield=91%)

2,6-dibromo-3,5-dimethyl-1,1:4,1-terphenyl (126)

(70) In a glove box, Pd.sub.2(dba).sub.3 (1.02 g, 1.11 mmol), PCy.sub.3 (1.25 g, 4.45 mmol), compound 125 (8.04 g, 22.23 mmol), boronic acid 124 (5.03 g, 22.23 mmol) were added to a reaction vessel that was equipped with a stir bar. A degassed K.sub.3PO.sub.4 (14.16 g, 66.7 mmol) water solution was then added, followed by 100 ml anhydrous THF. The reaction mixture was then stirred at 60 C. for 3 days. After the reaction finished, the reaction mixture was diluted with EtOAc, then extracted by EtOAc three times, dried, filtered and concentrated. The final product was obtained after purification by column chromatography on silica gel. Colorless oil (yield=48%)

Triisopropyl((5-methoxy-3-(5-methoxy-2-((triisopropylsilyl)ethynyl)phenyl)-3,5-dimethyl-[1,1:2,1:4,1-quaterphenyl]-2-yl)ethynyl)silane (127)

(71) A 100 ml round flask was equipped with compound 126 (1.16 g, 2.79 mmol), boronic ester 122 (3.47 g, 8.36 mmol) in 50 ml toluene and 5 ml K.sub.2CO.sub.3 (2.31 g, 16.72 mmol) water solution. After bubbled with argon for 10 min, the catalyst Pd(PPh.sub.3).sub.4 (322 mg, 0.28 mmol) was added. The reaction mixture was then heated at reflux temperature overnight. The reaction was stopped after TLC indicated that the starting material was totally converted. The mixture was extracted with EtOAc (10 ml3), then the combined organic layer was dried, filtered and concentrated. The residue was purified by column chromatography yielding product 127. Yellow solid (yield=81%)

2-Ethynyl-3-(2-ethynyl-5-methoxyphenyl)-5-methoxy-3,5-dimethyl-1,1:2,1:4,1-quaterphenyl (128)

(72) Compound 127 (1.5 g, 1.8 mmol) was dissolved in 50 ml THF, and then TBAF (5.69 g, 18 mmol) was added to the yellow solution. After stirred for 2 h, the reaction mixture was washed with water and then extracted with EtOAc. The combined organic layer was dried over MgSO.sub.4 and filtered. The solvent was removed by rotation evaporator. The obtained white solid was used directly for the next step. White solid (yield=99%)

14-(3,5-Dimethyl-[1,1-biphenyl]-4-yl)-2,12-dimethoxybenzo[m]tetraphene (129)

(73) A 100 ml round flask was charged with compound 128 (1.1 g, 2.12 mmol) and PtCl.sub.2 (56.4 mg, 0.21 mmol), then the mixture was kept under vacuum condition for 20 min and refilled with argon. 60 ml of anhydrous toluene was added by syringe. The mixture was heated at 80 C. for 24 h until reaction finished which showed by TLC plate. The solvent was removed under vacuum condition and the residue was purified by chromatography yielding final product. White solid (yield=63%)

14-(3,5-Dimethyl-[1,1-biphenyl]-4-yl)benzo[m]tetraphene-2,12-diol (130)

(74) Compound 129 (250 mg, 0.48 mmol) was dissolved in 40 ml dry DCM under argon protection. Then, 5.78 mL 1M BBr.sub.3 (1.45 g, 5.78 mmol) was added dropwise to the solution at 0 C. The solution was then allowed to warm to room temperature and stirred for 6 h. Then, the reaction was quenched by adding 10 ml water slowly at 0 C. The mixture was washed with water and extracted with DCM. The organic layer was dried over MgSO.sub.4, filtered and concentrated. The residue was recrystallized from DCM/hexane (1:50). White green powder (yield=82%)

14-(3,5-Dimethyl-[1,1-biphenyl]-4-yl)benzo[m]tetraphene-2,12-diyl bis(trifluoromethanesulfonate) (131)

(75) Compound 130 (236 mg, 0.48 mmol) was dissolved in 20 ml DCM and cooled to 0 C. by an ice bath, then 0.36 ml Et.sub.3N (2.6 mmol) was added drop wise. 1M Tf.sub.2O (1.44 mL) solution was added by syringe. The ice bath was then removed and the mixture solution was warmed to room temperature and stirred for 4 h. After TLC showed the completion of the reaction, the solvent was removed and the residue was purified by chromatography yielding product. White solid (yield=78%)

2,2-(14-(3,5-dimethyl-[1,11-biphenyl]-4-yl)benzo[m]tetraphene-2,12-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (132)

(76) A Schlenk tube was charged with compound 131 (110 mg, 0.145 mmol), PdCl.sub.2(dppf) (6 mg, 0.007 mmol), 5 ml dry dioxane and Et.sub.3N (0.12 ml, 0.87 mmol), the solution was degassed and pinacolborane (0.08 mL, 0.58 mmol) was added. The mixture solution was then heated at refluxing temperature for 12 h. Then the solvent was removed and the residue was purified by chromatography. Light yellow oil (yield=71%)

2,12-Dibromo-14-(3,5-dimethyl-[1,1-biphenyl]-4-yl)benzo[m]tetraphene (5)

(77) Compound 131 (50 mg, 0.07 mmol) and CuBr.sub.2 (95 mg, 0.42 mmol) was added to a sealtube, then 2 ml THF, 6 ml Methanol and 4 ml water was added. The tube was sealed and heated at 120 C. overnight. The mixture was then extracted with DCM (5 mL3), dried over MgSO.sub.4, filtered and concentrated. The residue was purified by chromatography and HPLC to afford monomer 5. Colorless solid (Yield=60%)

(78) FD-MS: m/z=615.3

5. Synthesis of Monomers 6, 7 (Monomer Structure III)

(79) ##STR00036## ##STR00037##
Compound 133:

(80) A 50 mL round bottomflask equipped with a magnetic stir bar was charged with compound 132 (35 mmol), THF (100 mL), triethylamine (20 mL, 150 mmol), PdCl.sub.2(PPh.sub.3).sub.2 (500 mg, 0.7 mmol), CuI (150 mg, 0.754 mmol) and trimethylsilylacetylene (5.25 mL, 37.1 mmol) under argon atmosphere. The reaction mixture was stirred overnight at room temperature, diluted in CH.sub.2Cl.sub.2, washed with NH.sub.4Cl and dried over Mg.sub.2SO.sub.4. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography on silica gel with hexanes as eluent to afford the desired compound 133 (133a: 82%, 133b: 85%) as yellow orange oil.

(81) 133a: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.58 (d, 1H), 7.49 (dd, 1H), 7.24 (t, 1H), 7.16 (t, 1H), 0.28 (s, 9H);

(82) 133b: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.48 (s, 1H), 7.32 (dd, 1H), 7.18 (dd, 1H), 1.6 (s, 9H), 0.28 (s, 9H);

(83) Compound 134:

(84) A 250 mL round bottom flask equipped with a magnetic stir bar was charged with compound 133 (11.9 mmol), THF (100 mL). The temperature was cooled to 78 C. and n-BuLi (1.4 mL, 23.7 mmol) was added slowly. The reaction mixture was stirred for one hour and 1,2-diiodoethane was added (17.8 mmol). The reaction mixture was stirred overnight at room temperature, diluted in CH.sub.2Cl.sub.2, washed with H.sub.2O and dried over Mg.sub.2SO.sub.4. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography on silica gel with hexanes as eluent to afford the desired compound 134 (134a:88%, 134b:90%) as dark orange oil.

(85) 134a: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.55 (d, 1H), 7.47 (dd, 1H), 7.21 (t, 1H), 7.15 (t, 1H), 0.28 (s, 9H);

(86) 134b: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.58 (s, 1H), 7.38 (dd, 1H), 7.24 (dd, 1H), 1.55 (s, 9H), 0.27 (s, 9H);

(87) Compound 135:

(88) To a dimethylformamide (DMF) (100 mL) solution of compound 134 (32.3 mmole) placed in round bottom flask was added CuCl (32.3 mmol) equipped with a magnetic stirring bar. The reaction mixture was stirred for 6 h at 80 C. and quenched with 1.0 M HCl(aq). The aqueous layer was separated and extracted with 100 mL of diethyl ether. The combined ethereal layer was washed with brine and dried over Mg.sub.2SO.sub.4, concentration of the solution in vacuo gave a brown residue that was purified by column chromatography (dichloromethane/hexane= 1/10) to afford compound 135 (135a:78%, 135b:83%) as a yellow solid.

(89) 135a: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.82 (d, 1H), 7.55 (d, 1H), 7.28 (t, 1H), 7.12 (t, 1H); FD-MS (8 KV): m/z 453.9.

(90) 135b: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.86 (s, 1H), 7.66 (d, 1H), 7.23 (d, 1H), 1.45 (s, 9H); FD-MS (8 KV): m/z 565.8.

(91) Compound 136:

(92) Nitrogen was bubbled through a mixed solution of THF (100 mL), EtOH (20 mL) and water (20 mL) for 30 min, and to this solution was added compound 135 (4.96 mmol), Pd(PPh3)4 (0.5 mmol), K2CO3 (29.76 mmol) and bromo-naphthalene-boronic acid (9.95 mmol). The mixture was heated at 60 C. for 36 h. The solution was extracted three times with ethyl acetate. After removal of the solvent in vacuo, the crude material was purified by column chromatography (dichloromethane/hexane= 1/10) to afford compound 136 (136a:50%, 136b:56%) as a yellow solid.

(93) 136a: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 8.01 (s, 1H), 7.76 (d, 1H), 7.68 (d, 1H), 7.54 (s, 1H), 7.45 (m, 2H), 7.3 (m, 4H); .sup.13C-NMR (CD.sub.2Cl.sub.2, 250 MHz): 144.78, 138.74, 134.19, 133.49, 132.35, 131.45, 130.59, 130.45, 129.29, 128.34, 128.22, 127.51, 127.16, 127.07, 122.09, 121.32, 81.14, 76.81 FD-MS (8 KV): 611.8 m/z.

(94) 136b: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 8.28 (s, 1H), 8.23 (s, 1H), 8.14 (s, 1H), 8.01 (dd, 1H), 7.88 (dd, 1H), 7.64 (m, 2H), 7.36 (m, 2H); .sup.13C-NMR (CD.sub.2Cl.sub.2, 250 MHz): 145.58, 136.47, 134.14, 130.81, 129.55, 127.63, 126.82, 124.88, 124.65, 124.13, 124.08, 123.96, 123.54, 122.76, 117.85, 115.64, 77.38, 74.31, 33.68, 31.34. FD-MS (8 KV): 723.8 m/z.

(95) Monomers 6 and 7:

(96) A reaction tube containing PtCl.sub.2 (0.07 mmol) was dried in vacuo for 1 h, and vacuum was filled with nitrogen with a nitrogen balloon. To this round bottom flask was added compound 136 (0.74 mmol) and toluene (74 mL), and the mixture was stirred at 25 C. for 5 min before it was heated at 90 C. for 24 h. After removal of solvent in vacuo, the crude material was purified by column chromatography (dichloromethane/hexane=) to afford compound 6, respectively 7 (6:70%, 7:78%) as a yellow solid.

(97) 6: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 9.55 (dd, 1H), 8.28 (s, 1H), 7.78 (d, 1H), 7.68 (m, 3H), 7.69 (t, 1H), 7.54 (t, 1H), 7.25 (t, 1H), 6.74 (t, 1H); .sup.13C-NMR (CD.sub.2Cl.sub.2, 250 MHz): 138.82, 133.26, 131.84, 131.64, 130.38, 130.01, 128.59, 128.47, 126.82, 126.74, 126.39, 126.09, 125.81, 124.53, 124.04, 120.65, 116.11, 115.72. FD-MS (8 KV): 611.7 m/z.

(98) 7: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 9.54 (dd, 1H), 8.28 (s, 1H), 7.81 (d, 1H), 7.65 (m, 4H), 7.24 (t, 1H), 6.75 (t, 1H), 1.34 (s, 9H); .sup.13C-NMR (CD.sub.2Cl.sub.2, 250 MHz):150.55, 140.11, 134.29, 132.95, 132.82, 131.84, 130.76, 129.76, 129.29, 127.87, 127.75, 127.61, 127.19, 126.75, 125.67, 123.83, 123.48, 117.36, 35.09, 31.28. FD-MS (8 KV): 723.9 m/z.

6. Synthesis of Monomer 8 (Monomer Structure X)

(99) ##STR00038## ##STR00039##
Compound 137:

(100) A mixture of dimethyl-bromoaniline (0.05 mol), H.sub.2O (100 mL), and 37% aq.HCl (100 mL) was heated to 80 C. while stirring. The mixture was stirred 30 min followed by cooling to 0 C. on an ice/water bath. NaNO.sub.2 (0.055 mol) was added maintaining the internal temperature below 10 C. The resulting clear, orange solution was stirred at 0 C. for 30 min followed by addition of KI (0.055 mol) as a solution in H.sub.2O (50 mL) keeping the internal temperature below 10 C. The black suspension was allowed to reach room temperature and stirred for 12 h. The suspension was extracted with DCM, washed with water and brine, dried over with Mg.sub.2SO.sub.4, concentration of the solution in vacuo gave a brown residue that was purified by column chromatography (hexane) to afford compound 137 (60%) as a yellow orange oil.

(101) 137: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.34 (s, 1H), 7.03 (s, 1H), 2.54 (s, 3H), 2.28 (s, 3H).

(102) Compound 138:

(103) A 50 mL round bottomflask equipped with a magnetic stir bar was charged with compound 137 (35 mmol), THF (100 mL), triethylamine (20 mL, 150 mmol), PdCl.sub.2(PPh.sub.3).sub.2 (500 mg, 0.7 mmol), CuI (150 mg, 0.754 mmol) and trimethylsilylacetylene (5.25 mL, 37.1 mmol) under argon atmosphere. The reaction mixture was stirred overnight at room temperature, diluted in CH.sub.2Cl.sub.2, washed with NH.sub.4Cl and dried over Mg.sub.2SO.sub.4. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography on silica gel with hexanes as eluent to afford the desired compound 138 (82%) as yellow solid.

(104) 138: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.43 (s, 1H), 7.13 (s, 1H), 2.58 (s, 3H), 2.32 (s, 3H), 0.28 (s, 9H);

(105) Compound 139:

(106) To a dimethylformamide (DMF) (100 mL) solution of compound 138 (32.3 mmole) placed in round bottom flask was added CuCl (32.3 mmol) equipped with a magnetic stirring bar. The reaction mixture was stirred for 6 h at 80 C. and quenched with 1.0 M HCl(aq). The aqueous layer was separated and extracted with 100 mL of diethyl ether. The combined ethereal layer was washed with brine and dried over Mg.sub.2SO.sub.4, concentration of the solution in vacuo gave a brown residue that was purified by column chromatography (dichloromethane/hexane=) to afford compound 139 (78%) as a yellow solid.

(107) 139: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.23 (s, 1H), 6.95 (s, 1H), 2.39 (s, 3H), 2.23 (s, 3H). FD-MS (8 KV): 415.7 m/z.

(108) Compound 140:

(109) A 250 mL round bottom flask equipped with a magnetic stir bar was charged with compound 139 (11.9 mmol), THF (100 mL). The temperature was cooled to 78 C. and n-BuLi (1.4 mL, 47.4 mmol) was added slowly. The reaction mixture was stirred for one hour and 1,2-diiodoethane was added (35.6 mmol). The reaction mixture was stirred overnight at room temperature, diluted in CH.sub.2Cl.sub.2, washed with H.sub.2O and dried over Mg.sub.2SO.sub.4. The solvent was removed under reduced pressure and the crude product was purified by column chromatography (dichloromethane/hexane=) to afford the desired compound 140 (80%) as yellow solid.

(110) 140: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 7.48 (s, 1H), 6.97 (s, 1H), 2.41 (s, 3H), 2.20 (s, 3H). FD-MS (8 KV): 509.8 m/z.

(111) Compound 141:

(112) Nitrogen was bubbled through a mixing solution of THF (100 mL), EtOH (20 mL) and water (20 mL) for 30 min, and to this solution was added compound 140 (4.96 mmol), Pd(PPh.sub.3).sub.4 (0.5 mmol), K.sub.2CO.sub.3 (29.76 mmol) and bromo-naphthalene-boronic acid (9.95 mmol). The mixture was heated at 60 C. for 36 h. The solution was extracted three times with ethyl acetate. After removal of the solvent in vacuo, the crude material was purified by column chromatography (dichloromethane/hexane=) to afford compound 141 (56%) as a yellow solid.

(113) 141: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 8.13 (s, 1H), 7.98 (s, 1H), 8.00 (s, 1H), 7.83 (t, 1H), 7.72 (d, 3H), 7.61 (t, 1H), 7.37 (t, 1H), 7.11 (s, 1H), 6.98 (s, 1H), 2.39 (s, 3H), 2.35 (s, 3H). FD-MS (8 KV): 667.9 m/z.

(114) Compound 142:

(115) A solution of compound 141 (1.55 mmol) in dry CH.sub.2Cl.sub.2 (100 mL) was maintained at 78 C. with an acetone-liquid N2 bath. To this solution was added ICI (3.41 mL, 1 M solution in CH.sub.2Cl.sub.2), using a standard syringe. The reaction was stirred for 3 h. Quenched with a saturated sodium sulfite solution and warmed to RT. Extracted with CH.sub.2Cl.sub.2 (230 mL) and dried over MgSO.sub.4. After removal of solvent in vacuo, the crude material was purified by column chromatography (dichloromethane/hexane=) to afford compound 142 (87%) as a yellow solid.

(116) 142: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 8.91 (s, 1H), 7.89 (s, 1H), 7.47 (d, 1H), 7.26 (s, 1H), 7.22 (dd, 1H), 7.17 (dd, 1H), 6.70 (t, 1H), 2.70 (s, 3H), 2.48 (s, 3H); 13C-NMR (CD2Cl2, 250 MHz): 149.46, 134.66, 134.37, 132.61, 132.34, 131.41, 131.36, 131.05, 130.75, 130.09, 127.41, 126.54, 125.43, 125.15, 123.75, 122.86, 114.75, 100.49, 24.56, 20.40. FD-MS (8 KV): 919.9 m/z.

(117) Monomer 8:

(118) A solution of 142 (0.108 mmol) in dry THF (100 mL) was irradiated in a standard immersion well photoreactor with 360 nm high pressure mercury vapor lamp (4*360 nm) for 2 h. The reaction mixture was then washed with aqueous sodium thiosulfate, water, brine and dried over anhydrous MgSO.sub.4. The solvent was removed under vacuum and recrystallization from chloroform afforded monomer 8 (50%) as a yellow solid.

(119) 8: .sup.1H-NMR (CD.sub.2Cl.sub.2, 250 MHz): 9.21 (s, 1H), 8.30 (s, 1H), 8.00 (s, 1H), 7.73 (dd, 1H), 7.32 (m, 3H), 6.79 (t, 1H), 2.64 (s, 3H), 2.56 (s, 3H); .sup.13C-NMR (CD2Cl2, 250 MHz): 139.12, 134.39, 134.24, 133.91, 132.78, 131.13, 130.42, 130.09, 129.85, 129.65, 129.58, 128.00, 127.86, 126.97, 126.72, 125.78, 125.39, 117.47, 22.34, 19.91. FD-MS (8 KV): 667.8 m/z.

7. Surface Confined Preparation of GNR v-vii (RH)

(120) A Au (111) single crystal (Surface Preparation Laboratory, Netherlands) was used as the substrate for the growth of the GNR structures v, vi and vii from the corresponding monomers 5, 6 and 7, respectively. The Au surface was cleaned under ultra-high vacuum conditions (UHV, pressure 110.sup.10 mbar) by repeated cycles of argon ion bombardment and annealing to 470 C. Once the surface was clean, the precursor monomers were deposited onto the substrate held at 200 C. by sublimation at rates of 0.1 nm/min. After monomer deposition, the Au (111) substrate was kept at this temperature for a few minutes (1-15 min) to complete polymerization. Subsequently the sample was annealed to 400 C. for 15 min to induce cyclodehydrogenation and thus the formation of the targeted GNR structures. A variable-temperature STM (VT-STM) from Omicron Nanotechnology GmbH, Germany, was used to characterize the morphology of the GNR structures. Images were taken at 35 K (LHe cooling).

(121) FIGS. 2, 3 and 4 show STM images of the polymer structures obtained after monomer deposition (a) and of the final GNR structures (b) obtained after cyclodehydrogenation. The characteristic apparent height of the final GNR structures is of 0.17 to 0.20 nm, in agreement with other GNR structures [e.g. Nature 466, 470-473 (2010)].

(122) The experiments are summarized in Table 1.

(123) TABLE-US-00002 TABLE 1 Molecule Intermediate Polymer Graphene Nanoribbon 0

8. Preparation of GNR iii (RH) from Monomer 6

(124) A Au (111) single crystal (Surface Preparation Laboratory, Netherlands) was used as the substrate for the growth of the N=5 cove-edge zigzag GNR structure iii from monomer 3. The Au surface was cleaned under ultra-high vacuum conditions (UHV, pressure 110.sup.10 mbar) by repeated cycles of argon ion bombardment and annealing to 470 C. Once the surface was clean, the precursor monomers 3 were deposited onto the substrate held at 200 C. by sublimation at rates of 0.1 nm/min. After monomer deposition, the Au (111) substrate was kept at this temperature for a few minutes (1-15 min) to complete polymerization. Subsequently the sample was annealed to 450 C. for 15 min to induce cyclodehydrogenation and thus the formation of the targeted GNR structure iii. A low-temperature scanning tunneling microscope (LT-STM) from Omicron Nanotechnology GmbH, Germany, was used to characterize the morphology of the N=5 cove-edge zigzag GNR structures. Images were taken at 5 K (LHe cooling).

(125) FIG. 1 a) shows a high resolution STM image of the terminus of the GNR structure iii. The image was taken at U=0.9V, I=0.4 nA, 5 K (LHe cooling). The apparent height is 0.17 nm, in agreement with results for other GNR structures [e.g. Nature 466, 470-473 (2010)].

(126) FIG. 1 b) shows the same STM image with a chemical model of the corresponding GNR structure iii overlaid.

9. Preparation of GNR i (RH) from Monomer 9

(127) A Au (111) single crystal (Surface Preparation Laboratory, Netherlands) was used as the substrate for the growth of the GNR structure i from monomer 9. The Au surface was cleaned under ultra-high vacuum conditions (UHV, pressure 110.sup.10 mbar) by repeated cycles of argon ion bombardment and annealing to 470 C. Once the surface was clean, the precursor monomers 9 were deposited onto the substrate held at 170 C. by sublimation at rates of 0.1 nm/min. After monomer deposition, the Au (111) substrate was kept at this temperature for a few minutes (1-15 min) to complete polymerization. Subsequently the sample was annealed to 370 C. for 15 min to induce cyclodehydrogenation and thus the formation of the targeted GNR structure i. A variable-temperature STM (VT-STM) from Omicron Nanotechnology GmbH, Germany, was used to characterize the morphology of the GNR structures. Images were taken at 35 K (LHe cooling).