Supplementary Material for "Cove-edged Chiral Graphene Nanoribbons with Chirality-Dependent Bandgap and Carrier Mobility"

Supporting Information Cove-edged Chiral Graphene Nanoribbons with Chirality-Dependent Bandgap and Carrier Mobility Kun Liu[a], Wenhao Zheng[c], Silvio Osella[d], Zhenlin Qiu[a], Steffen Böckmann[e], Wenhui Niu[a], [b], Laura Meingast[f], Hartmut Komber[g], Sebastian Obermann[a], Roland Gillen[f], Mischa Bonn[c], Michael Ryan Hansen[e], Janina Maultzsch[f], Hai I. Wang[c], [h], Ji Ma[a], [b]*, Xinliang Feng[a], [b]* [a] Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstrasse 4, 01062 Dresden, Germany E-mail: [email protected], xinliang.f[email protected]e [b] Max Planck Institute of Microstructure Physics, Weinberg 2, Halle, 06120 Germany [c] Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany [d] Chemical and Biological Systems Simulation Lab, Center of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland [e] Institute of Physical Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany [f] Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstr. 7, 91058, Erlangen, Germany [g] Leibniz-Institut für Polymerforschung Dresden e. V., Hohe Straße 6, 01069 Dresden, Germany [h] Nanophotonics, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands Contents 1. Definition of (n,m)-cGNR and (n,m)-CcGNR...................................................................... 3 2. General methods and material ................................................................................................ 4 3. Synthetic procedures and characterization ............................................................................. 5 4. Optical properties of model compounds, polymer precursors and GNRs ............................ 16 5. FT-IR and Raman characterization ...................................................................................... 17 6. Solid-state NMR analysis .................................................................................................... 22 7. Theoretical calculations ........................................................................................................ 22 8. Terahertz spectroscopic study .............................................................................................. 28 9. NMR spectra......................................................................................................................... 27 10. References .......................................................................................................................... 41 1. Definition of (n,m)-cGNR and (n,m)-CcGNR The chiral graphene nanoribbons (cGNRs) are defined by either chiral angle θ or chiral vector (n,m), where n and m are the translational indices of the unit vectors of the graphene lattice. Basically, we present here n ˃ m, since (n,m) and (m,n) are structurally equivalent. In addition, the chirality can also be described by the chiral angle θ = arcsin√3 4(𝑚2 𝑛2+𝑛𝑚+𝑚2). Following this definition, zigzag-edged GNR and armchair-edged GNR can be defined by θ = 0 o and θ = 30 o, respectively. In general, this rule is applicable for any edge structures, which can adapt the chiral vector (n,m) or chiral angle θ. In this work, a family of cGNRs and corresponding cove-edged chiral graphene nanoribbons (CcGNRs) with the same unit width and same translational index (m = 2) are proposed by varying n. The edge structure for each repeating motif of (n,m)-CcGNR is composed of n/2 in the a1 direction and m/2 cove units in the a2 direction, while the chiral angle decreased with increasing n. Figure S1. Schematic demonstration of (n,m)˗cGNRs and corresponding (n,m)˗CcGNRs, when m=2. 2. General methods and material General remarks: All the reagents were obtained from TCI, BLDpharm, Sigma Aldrich, abcr, Acros organics or Strem. All these chemicals were used as received without further purification. Anhydrous toluene, tetrahydrofuran (THF), dimethylformamide (DMF) and dichloromethane (DCM) were obtained from MBRAUN MB-SPS-5 solvent purification system. All the sensitive reactions were performed using standard vacuum-line and Schlenk techniques. Thin layer chromatography (TLC) was performed on silica-coated aluminum sheets with a fluorescence indicator (TLC silica gel 60 F254, purchased from Merck KGaA). Column chromatography was performed on silica (SiO2, particle size 0.063-0.200 mm, purchased from VWR). NMR spectra were recorded on a Bruker AV-II 300 MHz spectrometer operating at 300.13 MHz for 1H and at 75.47 MHz for 13C, on a Bruker Avance III 500 MHz spectrometer operating at 500.13 MHz for 1H and at 125.77 MHz for 13C or on a Bruker Avance III 600 MHz spectrometer operating at 600.16 MHz for 1H and 150.92 MHz for 13C. Chemical shifts (δ) were reported in ppm. Coupling constants (J values) were presented in Hertz (Hz). 1H NMR chemical shifts were referenced to CD2Cl2 (5.32 ppm) or toluene-d8 (2.09 ppm). 13C NMR chemical shifts were referenced to CD2Cl2 (53.7 ppm) or toluene-d8 (CD3: 21.5 ppm). The following abbreviations are used to describe peak patterns as appropriate: s = singlet, d = doublet, t = triplet, q = quartet, and m = multiplet. High resolution mass spectrometry (HRMS) was performed on a Bruker Autoflex Speed MALDI TOF MS (Bruker Daltonics, Bremen, Germany) using DCTB (trans-2-[3-(4-tertbutylphenyl)-2-methyl-2-propenylidene]malononitrile) as matrix. High-Resolution Atmospheric Pressure Chemical Ionization (APCI) mass spectra were recorded with Agilent 6538 Ultra High Definition (UHD) Accurate-Mass Q-TOF LC/MC system, using the positive mode. HR‐ESI mass spectra were recorded on a Waters Xevo G2‐XS QTOF mass spectrometer. Analytical size-exclusion chromatography (SEC) was performed on gel permeation chromatography (GPC) with an Aligent Technologies 1260 Infinity II LC system equipped with two Resipore columns and RI and UV-vis detection using chloroform as eluent with a flow rate of 1 mL min-1 at a temperature of 40oC. The molar masses were calculated relative to polystyrene standards with low dispersity. UV-visible spectra were measured on an Agilent Cary 5000 UV-vis-NIR spectrophotometer by using 10 mm optical-path quartz cell at room temperature. Fluorescence spectra were recorded at room temperature on a PerkinElmer Fluorescence Spectrometer LS 55 using a 10 mm fluorescence quartz cell. Fouriertransform infrared spectroscopy (FT-IR) was conducted with on a Bruker Optics ALPHA-E spectrometer with a universal Zn-Se ATR (attenuated total reflection) accessory in the 400−4000 cm–1. Raman spectroscopy of nanoribbon powder was performed using a Horiba LabRam HR Evolution confocal Raman microscope, a 532 nm laser, a 600 lines/mm grating, an ultra-low frequency module (ULF) and a 100x long working distance objective. The laser spot was widened to 2x2 µm² and the power was around 55 µW. 3. Synthetic procedures and characterization Scheme 1. Synthetic route toward 1, 2, 14 and 15. Regents and conditions: (a) (triisopropylsilyl)acetylene, CuI, PdCl2(PPh3)2, THF/TEA, r.t., 12 h, 95%; (b) n-BuLi, I2, THF, -78 °C, 16 h, 97%; (c) i. (3-bromonaphthalen-2-yl)boronic acid, Pd(PPh3)4, K2CO3, THF/EtOH/H2O, 60 oC, 36 h; ii. TBAF, THF, r.t., 20 min, 79%; (d) NBS, AgNO3, acetone, r.t., 1 h, 66%; (e) InCl3, toluene, 95 oC, 24 h, 87%; (f) CuI, piperidine, toluene, air, r.t., 6 h, 83%; (g) PtCl2, toluene, 90 oC, 24 h, 93%; (h) 2chloroiodobenzene, Pd(PPh3)4, Na2CO3, nBu4NBr, THF/EtOH/H2O, 60 oC, 10 h, 85%; (i) n-BuLi, triisopropyl borate, THF, -78 °C, 16 h, 61%; (j) (3-(2-chlorophenyl)naphthalen-2-yl)boronic acid, Pd(PPh3)4, K2CO3, toluene/EtOH/H2O, 95 oC, 48 h, 55% for 14 and 60% for 15; (k) DDQ, TfOH, DCM, 0 oC, 45 min, 62% for 1 and 65% for 2. 1-bromo-2-iodo-4-tert-butylbenzene (3)1, (3-bromonaphthalen-2-yl)boronic acid (6)2 and 11,11'-dibromo-8,8'-di-tert-butyl-5,5'-bichrysene (11)2 were synthesized according to previous reported procedure. ((2-bromo-5-(tert-butyl)phenyl)ethynyl)triisopropylsilane (4) To a degassed solution of compound 3 (6.78 g, 20.0 mmol) in THF (30 mL) and triethylamine (30 mL) were added PdCl2(PPh3)2 (280.76 mg, 0.4 mmol) and CuI (152.36 mg, 0.8 mmol), then (triisopropylsilyl)acetylene (4.94 mL, 22.0 mmol) was added via a syringe. After stirring at room temperature overnight, the reaction mixture was diluted with DCM (100 mL), washed with a saturated aqueous solution of ammonium chloride (50 mL), brine (50 mL) and dried over MgSO4. The solvent was removed under reduced pressure and the residue was purified by column chromatography on silica gel (eluent: iso-hexane) to give compound 4 as a yellow oil (7.43 g 95%). 1H NMR (300 MHz, CD2Cl2): 7.52 (d, 2.5 Hz, 1H), 7.50 (d, 8.6 Hz, 1H), 7.22 (dd, 8.6 Hz, 2.5 Hz, 1H), 1.30 (s, 9H), 1.17 (s, 21H). 13C NMR (75 MHz, CD2Cl2): 150.90, 132.33, 131.20, 127.63, 125.32, 122.79, 105.75, 95.71, 34.83, 31.23, 18.91, 11.80. ((5-(tert-butyl)-2-iodophenyl)ethynyl)triisopropylsilane (5) A 250 mL round bottom flask equipped with a magnetic stirrer was charged with compound 4 (7.87 g, 20.0 mmol) and 70 mL of THF. The solution was purged with argon for 30 min. Then the temperature was cooled to -78 oC and n-BuLi (1.6 M in hexanes, 16.25 mL) was added dropwise. The reaction mixture was stirred for one hour and I2 was added (7.61 g, 30.0 mmol in 30 mL of degassed THF). The reaction mixture was stirred at room temperature overnight then diluted with DCM, washed with NaS2O3 and dried over MgSO4. The solvent was removed under reduced pressure and the crude product was purified by flash chromatography on silica gel with iso-hexane to afford the compound 5 as a yellow oil (8.54 g, 97%). 1H NMR (300 MHz, CD2Cl2): 7.75 (d, 8.4 Hz, 1H), 7.50 (d, 2.5 Hz, 1H), 7.06 (dd, 8.4, 2.5 Hz, 1H), 1.29 (s, 9H), 1.17 (s, 21H). 13C NMR (75 MHz, CD2Cl2): 151.77, 138.73, 130.68, 129.89, 127.74, 108.89, 97.24, 94.84, 34.83, 31.13, 18.93, 11.80. HRMS (ESI, m/z): calcd for [M+H]+: 441.1469; observed 441.1453, error = -3.63 ppm. ((2-(3-bromonaphthalen-2-yl)-5-(tert-butyl)phenyl)ethynyl)triisopropylsilane (7-1) A solution of compound 5 (7.93 g, 18.0 mmol), compound 6 (4.74 g, 18.9 mmol) and K2CO3 (7.46 g, 54.0 mmol) in THF (100 mL), EtOH (20 mL) and water (20 mL) was purged with argon for 30 min. Then to this solution was added Pd(PPh3)4 (1.04 g, 0.9 mmol). The reaction mixture was stirred at 60 °C for 24 h. Afterward, the reaction mixture was extracted three times with DCM, washed with Brine and dried over MgSO4. The solvent was removed under reduced pressure and the residue was purified by column chromatography on silica gel with iso-hexane to afford compound 7-1 (7.57 g, 81%). 1H NMR (300 MHz, CD2Cl2): 8.19 (s, 1H), 7.83 – 7.80 (m, 3H), 7.68 (d, 1H), 7.55 – 7.48 (m, 3H), 7.32 (d, 1H), 1.44 (s, 9H), 0.85 (s, 21H). 13C NMR (75 MHz, CD2Cl2): 151.29, 141.92, 139.73, 134.38, 132.68, 131.39, 130.75, 129.99, 129.48, 128.32, 127.22, 126.97, 126.79, 125.79, 123.56, 122.20, 106.47, 94.10, 35.01, 31.54, 18.64, 11.59. HRMS (ESI, m/z): calcd for [M+H]+: 519.2078; observed 519.2067, error = -2.12 ppm. 2-bromo-3-(4-(tert-butyl)-2-ethynylphenyl)naphthalene (7) A solution of THF (20 ml) and compound 7-1 (1.43 g, 2.74 mmol) was bubbled with argon for 30 min, then 4.12 mL of TBAF (1 M in the THF) was added dropwise. After 20 min, the reaction was quenched with methanol and the solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel with iso-hexane to afford compound 7 as a yellow oil (975.6 mg, 98%). 1H NMR (300 MHz, CD2Cl2): 8.21 (s, 1H), 7.86 – 7.81 (m, 3H), 7.69 (d, 1H), 7.56 – 7.50 (m, 3H), 7.30 (d, 1H), 2.94 (s, 1H), 1.41 (s, 9H). 13C NMR (75 MHz, CD2Cl2): 151.42, 141.48, 139.21, 134.14, 132.42, 131.33, 130.65, 130.22, 130.18, 128.26, 127.43, 127.08, 127.03, 126.23, 121.94, 121.89, 83.23, 80.00, 34.95, 31.38. HRMS (ESI, m/z): calcd for [M+H]+: 363.0743; observed 363.0746, error = 0.83 ppm. 2-bromo-3-(2-(bromoethynyl)-4-(tert-butyl)phenyl)naphthalene (8) To a degassed solution of compound 7 (917.60 mg, 2.53 mmol) in acetone (30 mL) were added NBS (539.45 mg, 3.03 mmol) and AgNO3 (42.91 mg, 252.58 μmol). The resulting mixture was stirred at room temperature for 1 h. Afterward, the reaction mixture was filtered and the filtrate was concentrated under vacuum. The crude product was purified by column chromatography on silica gel with iso-hexane affording compound 8 as a colorless oil (736.4 mg, 66%). 1H NMR (300 MHz, CD2Cl2): 8.25 (s, 1H), 7.88 – 7.83 (m, 3H), 7.71 (d, 1.9 Hz, 1H), 7.58 – 7.52 (m, 3H), 7.33 (d, 8.1 Hz, 1H), 1.44 (s, 9H). 13C NMR (75 MHz, CD2Cl2): 151.43, 141.44, 139.00, 134.17, 132.47, 131.47, 130.76, 130.38, 130.14, 128.31, 127.45, 127.12, 127.05, 126.20, 122.54, 121.85, 80.03, 52.23, 34.98, 31.44. 5,11-dibromo-2-(tert-butyl)chrysene (9) To a mixture of compound 8 (789.3 mg, 1.78 mmol) and InCl3 (790.1 mg, 3.56 mmol) was added degassed anhydrous toluene (45 mL). The reaction mixture was stirred at 95 °C for 24 h under argon atmosphere. After the reaction, the solvent was evaporated under reduced pressure and the residue was purified by flash chromatography on silica gel with eluent (isohexanes/DCM 20:1) to give compound 9 (687 mg, 87%). 1H NMR (600 MHz, CD2Cl2): 9.36 – 9.35 (m, 1H), 9.30 (dt, 9.0, 0.7 Hz, 1H), 8.28 (s, 1H), 8.27 (s, 1H), 7.84 – 7.82 (m, 1H), 7.79 (d, 2.2 Hz, 1H), 7.70 (dd, 9.1 Hz, 2.2 Hz, 1H), 7.62 – 7.60 (m, 2H), 1.47 (s, 9H). 13C NMR (150 MHz, CD2Cl2): 151.13, 134.83, 134.34, 132.89, 132.59, 129.72, 129.40, 129.39, 127.81, 127.76, 127.56, 127.32, 127.03, 125.41, 124.12, 122.62, 116.33, 116.08, 35.18, 31.32. HRMS (MALDI-TOF, m/z): calcd for [C22H18Br2]+, 441.9750; observed 441.9743, error = -1.58 ppm. 2-bromo-3-(2-chlorophenyl)naphthalene (12) A mixture of 2-chloroiodobenzene (3.53 g, 14.81 mmol), compound 6 (3.1 g, 12.34 mmol), Na2CO3 (3.27 g, 30.85 mmol), nBu4NBr (3.98 g, 12.34 mmol), THF (75 mL), EtOH (35 mL) and water (35 mL) in a 250 mL three-neck flask was purged with argon for 30 min. Then Pd(PPh3)4 (427.85 mg, 0.37 mmol) was added and the reaction mixture was stirred at 60 oC for 10 h. After the reaction, the mixture was extracted three times with EA, washed with brine and dried over MgSO4. The solvent was removed under reduced pressure and the residue was applied to chromatography on silica gel with eluent (iso-hexane:DCM = 12:1) to give compound 12 (3.32 g, 85%). 1H NMR (300 MHz, CD2Cl2): 8.25 (s, 1H), 7.88 – 7.84 (m, 2H), 7.79 (s, 1H), 7.62 – 7.54 (m, 3H), 7.47 – 7.36 (m, 3H). 13C NMR (75 MHz, CD2Cl2): 140.39, 138.26, 134.28, 134.11, 132.42, 131.83, 131.41, 130.37, 129.85, 129.70, 128.28, 127.62, 127.18, 127.14, 127.01, 121.72. HRMS (MALDI-TOF, m/z): calcd for [C16H10BrCl]+, 317.9629; observed 317.9619, error = -3.14 ppm. (3-(2-chlorophenyl)naphthalen-2-yl)boronic acid (13) To a degassed solution of compound 12 (2.43 g, 7.65 mmol) in THF (100 mL) was added dropwise n-BuLi (7.17 mL, 1.6 M in hexane, 11.48 mmol) at ‒78 oC. After stirring at this temperature for 1 h, triisopropyl borate (3.53 mL, 15.30 mmol) was added dropwise. The reaction mixture was gradually warmed to room temperature and stirred for 16 h. Afterward, the reaction was quenched by adding 1 N HCl and stirred at room temperature for 30 min. Most of the THF was then evaporated and the mixture was extracted with EA for 3 times. The organic layers were washed with brine and dried over MgSO4. The solvents were evaporated under reduced pressure and the obtained residue was recrystallized from EA and iso-hexane in the freezer to afford the compound 13 as a white solid (1.31 g, 61%). 1H NMR (300 MHz, DMSOd6): 8.17 (s, 1H), 7.98 – 7.89 (m, 2H), 7.77 (s, 2H), 7.71 (s, 1H), 7.57 – 7.51 (m, 2H), 7.49 – 7.45 (m, 1H), 7.43 – 7.32 (m, 3H). 13C NMR (75 MHz, DMSO-d6): 142.16, 140.39, 133.41, 132.90, 132.22, 131.58, 131.52, 128.88, 128.48, 127.89, 127.71, 127.69, 126.67, 126.61, 126.19. 2-(tert-butyl)-5,11-bis(3-(2-chlorophenyl)naphthalen-2-yl)chrysene (14) A mixture of compound 9 (400 mg, 0.91 mmol), compound 13 (766.71 mg, 2.71 mmol) and K2CO3 (750.10 mg, 5.43 mmol) in water (6 mL) toluene (60 mL) and EtOH (6 mL) was degassed for 30 min. Then Pd(PPh3)4 (209.06 mg, 0.18 mmol) was added. The reaction mixture was refluxed at 95 oC for 48 h under argon. After cooling to room temperature, the mixture was extracted three times with EA, washed with brine and dried over MgSO4. Afterward, the solvent was removed under vacuum and the residue was purified by silica gel column chromatography with iso-hexane:DCM (4:1) as eluent to give the compound 14 as an orange solid (411.29 mg, 60%). HRMS (MALDI-TOF, m/z): calcd for [C54H38Cl2]+, 756.2346; observed 756.2361, error = 1.98 ppm. The 1H and 13C NMR spectra of 14 are very complex and very rich in overlapping signals (Figs. S and S). This is caused by internal rotation around the signal bonds, which is slow on the NMR time scale. These rotational processes are evident from the correlation peaks in the EXSY spectrum (Fig. S) and result in multiple rotamers and thus a large number of signals. Therefore, no signals were listed, but 1D and 2D NMR spectra were given for reference (Fig. S – S). 8,8'-di-tert-butyl-11,11'-bis(3-(2-chlorophenyl)naphthalen-2-yl)-5,5'-bichrysene (15) A mixture of compound 11 (300 mg, 0.41 mmol), compound 13 (350.93 mg, 1.24 mmol) and K2CO3 (343.33 mg, 2.48 mmol) in water (3 mL) toluene (30 mL) and EtOH (3 mL) was degassed for 30 min. Then Pd(PPh3)4 (95.70 mg, 0.08 mmol) was added. The reaction mixture was refluxed at 95 oC for 48 h under Argon. After cooling to room temperature, the mixture was extracted three times with EA, washed with brine and dried over MgSO4. Afterward, the solvent was removed under vacuum and the residue was purified by silica gel column chromatography with iso-hexane:DCM (4:1) as eluent to give the compound 15 as a paleyellow solid (236.87 mg, 55%). HRMS (MALDI-TOF, m/z): calcd for [C76H56Cl2]+, 1038.3754; observed 1038.3726, error = -2.69 ppm. The 1H and 13C NMR spectra of 15 are very complex and very rich in overlapping signals (Figs. S and S). This is caused by internal rotation around the signal bonds, which is slow on the NMR time scale. These rotational processes are evident from the correlation peaks in the EXSY spectrum (Fig. S) and result in multiple rotamers and thus a large number of signals. Therefore, no signals were listed, but 1D and 2D NMR spectra were given for reference (Fig. S – S). compound 1 4. Optical properties of model compounds, polymer precursors and GNRs Figure SXX. Spectroscopic characterization of 1 and 2. (a) Normalized UV-vis spectra of 1 and 2 in DCM. The optical bandgaps of 1 and 2 are estimated to be 2.25 eV and 1.98 eV, respectively. (b) Normalized fluorescence spectra of 1 and 2 in DCM. Figure SXX. Spectroscopic characterization of polymers P1 and P2. (a) Normalized UV-vis spectra and (b) emission spectra of polymers P1 and P2 in DCM. Figure SXX. Tauc-plot of the UV-vis data of (4,2)-CcGNR and (6,2)-CcGNR for a direct transition. 5. FT-IR and Raman characterization 5.1 IR-Simulation IR-spectra for P1, P2, (4,2)-CcGNR and (6,2)-CcGNR were obtained by geometry optimization and subsequent frequency calculation on an hseh1pbe/6-31G(d) level of theory using the Gaussian 16 software package.3 The obtained spectra were read from the .log file by the Multiwfn console application and scaled by factor 0.951. XYZ-files of the optimized structures can be found attached.4 (4,2)-CcGNR and (6,2)-CcGNR were represented by their dimers, respectively. We found that the polymers P1 and P2 can be sufficiently described by the structure illustrated below, since it contains all structural elements for both polymers. Obtaining IR-spectra without negative frequencies was difficult when extending the polymer model due to the high abundance of sterically locked conformers. Figure SXX shows the geometry-optimized structure of the (4,2)-CcGNR and (6,2)-CcGNR fragments as well as the polymer model. Figure SXX displays the chemical structure of these compounds. Colorful dots in the formulas indicate the vibrations marked in the spectra (Figure SXX). A detailed assignment of the experimental and theoretical frequencies can be found in Table SXX-XX. Figure SXX. Optimized structures of (a) a (4,2)-CcGNR dimer, (b) a (6,2)-CcGNR dimer and (c) a model for polymers P1 and P2. Figure SXX. Investigated structures and their most relevant assignments. (a) P1. (b) (4,2)-CcGNR dimer. (c) P2. (d) (6,2)-CcGNR dimer. Figure SXX. Simulated IR-spectra of the compounds. Peaks marked with Asterisk belong to artifacts due to the open-ended ribbon structure. In the case of the polymer model, methyl groups have been used to occupy the connection points. The fingerprint regions of (4,2)-CcGNR and (6,2)-CcGNR have been magnified by factor 4. Experimental Simulated Simulated and scaled Explanation 893 942, 930, 929, 927 896, 885, 884, 881 Antisymmetric wagging of SOLO (896 scaled) and symmetric SOLO modes ~875 924, 910 880, 866 Scaffold vibrations - 897 853 Wagging of hydrogen atoms at the end of the dimer (artifact) 838 + 811 876, 872, 866, 856 833, 829, 823, 814 DUO modes coupled with various scaffold vibrations 785-685 825, 792, 778, 773, 715 784, 753, 740, 735, 680 TRIO modes (784 scaled), QUATRO modes (753 scaled), oop and ip scaffold vibrations (740, 735, 680 scaled) Table SXX. Assignments for (4,2)-CcGNR. Experimental Simulated Simulated and scaled Explanation 891 939, 938, 920, 919, 917 893, 892, 875, 874, 872 Antisymmetric wagging of SOLO (896 scaled) and symmetric SOLO modes ~875 926, 920 881, 874 Scaffold vibrations 855-800 897, 896, 886, 877, 868 853, 852, 843, 834, 826 DUO modes + antisymmetric QUATRO coupled with various scaffold vibrations, red: artifacts, end of ribbon 785-710 825, 822, 822, 792, 783, 775, 765, 756 784, 782, 781, 753, 744, 737, 728, 717 TRIO modes (784, 782, 781, 728 scaled), QUATRO modes (753 scaled), oop and ip scaffold vibrations (744, 737, 717 scaled) Table SXX. Assignments for (6,2)-CcGNR. P1 P2 Simulated Simulated and scaled Explanation 888 889 922, 920, 911, 910, 907 877, 874, 866, 865, 862 SOLO modes on naphthalenes and chrysenes, asymmetric QUATRO (866 + 862 scaled) 823 + 799 828 + 798 871, 867, 860, 856, 851, 831 828, 824, 818, 814, 809, 790 Antisymmetric QUATRO coupled with SOLO modes (828 + 824 scaled), DUO modes chrysene (818 + 814 + 809 scaled) Ring breathing (790 scaled) 775 - 715 779 - 715 807, 806, 792, 787, 783, 778, 774, 773, 768, 763, 768, 766, 752, 748, 744, 739, 736, 734, 733, 730, 726, 726 Various oop + wagging (768, 766), QUATRO modes of the benzene units (752), Ring breathing + QUATRO benzene (748), QUATRO benzene + QUATRO chrysene (739 + 736 + 734), QUATRO naphthalene + chrysene (726) 698 698 720, 718 685, 683 Ip + oop scaffold vibrations Table SXX. Assignments for P1 and P2. 5.2 DFT calculation of Raman vibrational patterns of (4,2)-CcGNR and (6,2)-CcGNR Simulations of the vibrational spectra of the synthesized nanoribbons were performed using the SIESTA computational package performed with the computational package SIESTA5. The exchange-correlation interaction was included at the level of the PBE approximation. The wavefunctions of valence electrons were described through a single polarized triple-zeta (TZP) basis set of numerical atomic orbitals, while the core electrons were included implicitly through norm-conserving pseudopotentials from the Pseudo Dojo library6. The localization of the basis followed the standard split scheme with an energy shift of 5\,meV. Integrations in real and reciprocal space were performed on a grid defined by a planewave cutoff energy of 750\,Ry and 3 equally spaced k-points along the one-dimensional Brillouin zone, respectively. Using these parameters, we optimized the atomic positions and lattice vectors until the residual interatomic forces were smaller than 10-4 eV/Å and the stresses acting on the unit cell were smaller than 0.01 GPa. We then computed the vibrational spectra using a finite-displacement approach. The DFT simulations revealed that the typical vibrational patterns around 1600 cm-1 resemble that of the G mode in graphene/graphite.7,8 The lattice vibrations found around 1390 cm-1 are similar to the vibration leading to the D mode in graphene/graphite but include also vibrational contributions of the CH3 groups at the edges7,8. DFT simulations of (4,2)-CcGNR showed analogous results. Figure SXX. Typical vibrational patterns for certain frequency ranges obtained by DFT simulations for (6,2)-CcGNR: (a) around 1600 cm-1, the vibration resembles the G mode of graphene/graphite. (b) and (c) in the range around 1390 cm-1. The vibration in (b) resembles the vibration leading to the D mode in graphene/graphite with some additional contributions from the vibrations of the CH3 groups. At slightly lower frequencies (between 1332 – 1336 cm-1), we find a cluster of vibrations of mainly the CH3 groups. The mode shown in c) is representative of this group of modes. 7. Theoretical calculations 7.1 Geometry of the optimized structures Figure SXX. Optimized geometries of monomer, dimer and tetramer of 1 and 2. 7.2 Electronic properties Figure SXX. Calculated energy level of monomer, dimer, tetramer and infinite GNR of compound 1 and compound 2. A different behaviour is observed for the two different starting units 1 and 2. For (4,2)-CcGNR, the HOMO-LUMO gap slowly decreases while increasing the length of the oligomer up to the tetramer, and the (4,2)-CcGNR is mainly composed of longer oligomers. On the other hand, for (6,2)-CcGNR, a fast decrease in the HOMO-LUMO gap is observed while increasing the length of the oligomers, and the tetramer can be considered representative of (6,2)-CcGNR. In fact, the energy gap (1.15 eV) of the tetramer of (6,2)-CcGNR is very close to the energy gap of (6,2)-CcGNR itself, which is around 1.13 eV. However, for the structure of (4,2)-CcGNR a difference is observed, with an Energy gap of 1.16 eV for the tetramer and a band gap of 1.06 eV for the GNR. Yet, comparing the bandgap of the two ribbons, we can observe a slight opening of the gap of 0.1 eV going from (4,2)-CcGNR to (6,2)-CcGNR. Table SXX. The shapes of the frontier orbitals of monomer, dimer and tetramer for compound 1 and 2. HOMO LUMO 1 2 Dimer 1 Dimer 2 Tetramer 1 Tetramer 2 7.3 Optical properties The calculated UV-vis spectra for 1, 2 and the respective ribbons are reported in the following plot. Figure SXX. Calculated UV-vis absorption spectra of 1, 2, (4,2)-CcGNR and (6,2)-CcGNR. The computed absorption well represents the measured spectra (the differences in wavelength might be due to the absence of solvent contribution for the computed spectra). The first excited state for all oligomers studied relates to a HOMO to LUMO transition, and it is strongly allowed. For 1 and 2, the S1 is located at 550 and 630 nm, respectively. The next peak in the absorption spectra for 1 is found at 360 nm related to H-3 to LUMO, while for 2 is at 437 nm, which is related to a H-1 to L+1 transition. The third peak at 316 nm for 1 and 390 nm for 2 relates to a H-5 to LUMO for 1 and HOMO to L+2 transition for 2. When the ribbons are considered, the first excited state represents a HOMO to LUMO transition, and it is found at 1067 nm for (6,2)-CcGNR while it is blue shifted for (4,2)-CcGNR at 1006 nm. The next peak in the absorption spectra is related to a H-1 to L+1 transition for both ribbons, and is found at 945 nm for (6,2)-CcGNR and 802 nm for (4,2)-CcGNR, respectively. Finally, at a lower wavelength range, we found the last peak at 773 nm for (6,2)-CcGNR, which is related to a H-2 to L+2 transition, while for (4,2)-CcGNR it is located at 622 nm and relates to H-3 to L+1 transition. 7.4 Reduced mass analysis of (n,2)-CcGNR and (n,2)-cGNR Four different structures from (n,2)-CcGNR have been considered for this analysis, in which the repeating unit length is steadily increased from (4,2)-CcGNR up to (10,2)-CcGNR. This has a profound impact on the band dispersion, the reduced mass for both holes and electrons and in turn for the charge mobility. Band dispersion and bandgap plots are reported below. Figure SXX. Calculated energy level of a series of CcGNRs. As can be seen from the plots above, the length of the repeating unit strongly affects not only the band dispersion, but also the bandgap values. First of all, all these cove-shaped GNRs are semiconducting, with a band gap around 1 eV, and there is little dependence of the repeating unit size on the bandgap value, as both VBM and CBM have a similar energy going from (4,2)- CcGNR up to (10,2)-CcGNR. The strongest impact is observed for the band dispersion, in which the increase in the repeating unit length strongly affects it. In particular, the VBM and CBM bands become almost flat at (6,2) repeating unit, while a stronger dispersion is observed for (4,2)-CcGNR. This directly translates into higher values of reduced mass for both carriers, and hence a lower mobility (see Table SXX). In this table, we assume a scattering time in between 30 and 60 fs, and give a range of mobility values within this window. Table SXX. The different band dispersion for the (n,2)˗CcGNR with increasing n. Valence band maximum (VBM) and conduction band minimum (CBM) are reported in eV. Figure SXX. 13C NMR spectrum (75 MHz) of 8 in CD2Cl2 at room temperature. Figure SXX. 1H NMR spectrum (600 MHz) of 9 in CD2Cl2 at room temperature. Figure SXX. 13C NMR spectrum (150 MHz) of 9 in CD2Cl2 at room temperature. Figure SXX. 1H NMR spectrum (300 MHz) of 12 in CD2Cl2 at room temperature. Figure SXX. 13C NMR spectrum (75 MHz) of 12 in CD2Cl2 at room temperature. Figure SXX. 1H NMR spectrum (300 MHz) of 13 in DMSO-d6 at room temperature. Figure SXX. 13C NMR spectrum (75 MHz) of 13 in DMSO-d6 at room temperature. Figure SXX. 1H NMR spectrum (500 MHz) of 14 in CD2Cl2 at 30°C. Figure SXX. (a) 13C NMR spectrum (126 MHz) of 14 in CD2Cl2 at 30°C. (b) DEPT-135 13C NMR spectrum showing CH and CH3 signals positive and CH2 signals negative. Figure SXX. EXSY (ROESY) spectrum (500 MHz) of 14 in CD2Cl2 at 30°C. Blue correlation peaks result from exchange processes (EXSY) and red correlation peaks from spatial proximity (ROESY). Figure SXX. HSQC spectrum (region of aromatic CH) of 14 in CD2Cl2 at 30°C. Figure SXX. 1H NMR spectrum (500 MHz) of 15 in CD2Cl2 at 30°C. Figure SXX. (a) 13C NMR spectrum (126 MHz) of 15 in CD2Cl2 at 30°C. (b) DEPT-135 13C NMR spectrum showing CH and CH3 signals positive and CH2 signals negative. Figure SXX. EXSY (ROESY) spectrum (500 MHz) of 15 in CD2Cl2 at 30°C. Blue correlation peaks result from exchange processes (EXSY) and red correlation peaks from spatial proximity (ROESY). Figure SXX. HSQC spectrum (region of aromatic CH) of 15 in CD2Cl2 at 30°C. Figure SXX. 1H NMR spectrum (500 MHz) of 1 in toluene-d8 at 30°C. Figure SXX. COSY spectrum (region) of 1 in toluene-d8 at 30°C. Figure SXX. ROESY spectrum (region) of 1 in toluene-d8 at 30°C. Figure SXX. HSQC spectrum (region) of 1 in toluene-d8 at 30°C. The F1 axis shows the projection. 10. References (1) Wegner, H. A.; Reisch, H.; Rauch, K.; Demeter, A.; Zachariasse, K. A.; de Meijere, A.; Scott, L. T. 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