Supporting Information. Thermally Stable Radical-type Mechanochromic Polymers Based on Difluorenylsuccinonitrile

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1 Supporting Information Thermally Stable Radical-type Mechanochromic Polymers Based on Difluorenylsuccinonitrile Hio Sakai, Toshikazu Sumi, Daisuke Aoki, Raita Goseki, and Hideyuki tsuka* Department of Chemical Science and Engineering, Tokyo Institute of Technology, okayama, Meguro-ku, Tokyo , Japan Fax:

2 Table of Contents 1. General Information 2. Synthetic Procedures 3. Electron Paramagnetic Resonance (EPR) Study in Solutions 4. Grinding Tests and EPR Study in Solid States 5. The fading behavior of PMMA-DFSN-PMMA 6. References 2

3 1. General Information All solvents and reagents from Sigma-Aldrich, Wako Pure Chemical Industries, Tokyo Chemical Industry, and Kanto Chemical were used as received, unless otherwise noted. Copper (I) bromide (Cu) was washed with glacial acetic acid and then washed with ethanol and dried at 70 C. Anisole was distilled under reduced pressure over CaH 2 before used. Triethylamine was dried over 4A molecular sieves. Methyl methacrylate (MMA) was purified by basic alumina column (Merck KGaA) to remove the stabilizer prior to use. 1 H NMR spectroscopic measurements were carried out using 500 MHz uker spectrometer with tetramethylsilane (TMS) as an internal standard in chloroform-d (CDCl 3) or dimethyl sulfoxide-d 6 (DMS-d 6). IR spectra were obtained with a Perkin-Elmer Spectrum ne infrared spectrometer as thin films on K. UV-vis absorption measurements were carried out on a JASC V-650 spectrophotometer. Electro paramagnetic resonance (EPR) measurements were carried out on a JEL JES-X320 X- band EPR spectrometer equipped with a JEL DVT temperature controller. Size exclusion chromatography (SEC) measurements were carried out at 40 C on TSH HLC-8320 GPC system equipped with a guard column (TSH TSK guard column Super H-L), three columns (TSH TSK gel SuperH 6000, 4000, and 2500), a differential refractive index detector, and a UV-vis detector. Tetrahydrofuran (THF) was used as the eluent at a flow rate of 0.6 ml/min. Polystyrene (PS) standards (M n = ; M w/m n = ) were used to calibrate the SEC system. 3

4 2. Synthetic Procedure 2-1. Synthesis of DFSN 1, 2 K 3 [Fe() 6 ], NaH MeH / H 2 DFSN A 5 M NaH aqueous (11.8 ml) solution of potassium ferricyanide (1.43 g, 4.34 mmol) was added dropwise into 9-cyanofluorene (0.755 g, 3.95 mmol), which was prepared according to previous report, 1 in THF (31.6 ml) under water bath. The reaction mixture was allowed to stir for 5 min. After filtration of the reaction mixture, the crude product was washed with water and hexane. The obtained white powder was dried in vacuo at room temperature to give DFSN as white powder (0.651 g, 86%). 1 H NMR (500 MHz, CDCl 3) : δ/ppm (m, 16H, aromatic); 13 C NMR (125 MHz, CDCl 3): δ/ ppm , , , , , , , 53.92; FT-IR (K, cm -1 ) : 3430, 3063, 2370, 2236, 1712, 1604, 1479, 1446, 1293, 1192, 1157, 1106, 945, 877, 746, 676, 618, 467, Synthesis of 2-hydroxyl-methyl-fluorene (1) 3 H NaBH 4 EtH, r.t. H 1 To a solution of the commercial fluorene-2-carboxaldehyde (20.0 g, mol) in ethanol (200 ml) was added sodium borohydride (4.67 g, mol) at 0 ºC for a period of 10 min. The reaction mixture was stirred at room temperature for 1 h and then poured into water. The reaction mixture was extracted with dichloromethane, and the organic layer was washed with brine, dried over anhydrous MgS 4, and the solvent was removed to give compound 1 as light yellow solid. (19.4 g, 96%). 1 H-NMR (500 MHz, CDCl 3 ): δ/ppm (m, 2H, aromatic), (br, 2H, aromatic), (m, 3H, aromatic), 4.76 (d, J = 6.0 Hz, 2H, -CH 2-H), 3.89 (s, 2H, -C- CH 2 -C-), 1.73 (t, J = 5.8 Hz, 1H, -H). 4

5 2-3. Synthesis of 2-((tert-butyldimethylsilyloxy)methyl)-fluorene (2) TBSCl, imidazole H TBS DMF, r.t Hydroxyl-methyl-fluorene 1 (19.4 g, 98.8 mmol) and imidazole (10.1 g, mol) were added in a flask. The flask was degassed and back-filled with nitrogen three times. Anhydrous DMF (100 ml) was added into the flask under N 2 flow. A solution of tertbutyldimethylchlorosilane (TBSCl) (22.3 g, mol) in CH 2Cl 2 (50 ml) was added dropwise to this mixture at 0 ºC. The mixture was allowed to warm to room temperature. The reaction mixture was stirred at room temperature for 12 h and then poured into water. The reaction mixture was extracted with ethyl acetate, and the organic layer was washed with brine, dried over anhydrous MgS 4, and the solvent was removed. The crude product was purified by silica gel column chromatography eluting with ethyl acetate / n-hexane (1/50). The solvent was removed and dried under vacuum to give compound 2 as white solid (27.6 g, 90%). 1 H-NMR (500 MHz, CDCl 3 ): δ/ppm (m, 2H, aromatic), (m, 2H, aromatic), (m, 3H, aromatic), 4.82 (s, 2H, -CH 2--), 3.89 (s, 2H, -C-CH 2 -C-), 0.96 (s, 9H, -C-(CH 3) 3), 0.12 (s, 6H, - Si-(CH 3) 2-); 13 C NMR (125 MHz, CDCl 3): δ/ppm , , , , , , , , , , , , 65.44, 37.02, 26.16, 16.83, -5.02; FT-IR (K, cm 1 ): 3745, 3733, 2926, 2855, 2359, 2340, 1471, 1256, 1137, 1121, 1103, 1087, 1067, 1003, 981, 961, 944, 928, 911, 892, 876, 856, 837, 807, 785, Synthesis of 9-cyano-2-hydroxyl-methyl-fluorene (6) 1 1. n-buli, THF, -78 C H NH 2 H HCl K 2 C 3 H N H TBS 2. Ethylformate, THF, r.t. TBS EtH, r.t. TBS SCl 2 TBAF Et 2, r.t. TBS THF, r.t. H ((tert-Butyldimethylsilyloxy)methyl)-fluorene 2 (10.0 g, 32.2 mmol) was added in a flask and back-filled with nitrogen three times. THF (200 ml) was added into the flask under N 2 flow. 5

6 n-buli 1.64 M in hexane (43.2 ml 70.9 mmol) were added drop wise under 78 ºC, then ethyl formate (7.81 ml, 96.6 mmol) was added dropwise. The mixture was allowed to warm to room temperature and stirred for 30 min, and then poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine, dried over anhydrous MgS 4. After removing the solvent, the crude product of 3 was mixed with hydroxylamine hydrochloride (3.36 g, 48.3 mmol) and sodium bicarbonate (6.83 g, 64.4 mmol) in 200 ml ethanol and stirred at room temperature for 2 h. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to give the crude product of 4 which was used in next step without further purification. The mixture of oxime 4 and 3.48 ml (48.3 mmol) SCl 2 in 200 ml anhydrous THF was stirred at room temperature for 1 h and then poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine, dried over anhydrous MgS 4. After removing the solvent, the mixture of 5 and tetrabutylammonium fluoride (TBAF) 1 M THF solution (42.0 ml, 42 mmol) in 200 ml THF was stirred at room temperature for 12 h and then poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine, dried over anhydrous MgS 4 and removed the solvent. The crude product was purified by silica gel column chromatography eluting with ethyl acetate / n-hexane (2/3) and then recrystallized from chloroform to give compound 6 as light yellow solid (1.92 g, 27%). 1 H-NMR (500 MHz, DMSd 6: δ/ppm (m, 4H, aromatic), (m, 2H, aromatic), (m, 1H, aromatic), 4.93 (s, 1H, -C-CH-C-), 4.81 (d, J = 5.8 Hz, 2H, -C-CH 2 -H), 1.83 (t, J = 5.8 Hz 1H, -CH 2-H); 13 C NMR (125 MHz, DMS-d 6): δ/ppm , , , , , , , , , , , , , 36.91; FT-IR (K, cm 1 ): 3396, 3392, 3138, 3127, 3105, 3042, 3028, 2892, 2251, 1615, 1591, 1508, 1493, 1475, 1455, 1327, 1301, 1275, 1247, 1221, 1213, 1172, 1150, 1132, 1110, 1097, 1024, 933, 871, 860, 823, 763, 741, 714, 629, 591, Synthesis of DFSN-diol 2 K 3 [Fe() 6 ], NaH H H MeH / H 2, r.t. H 6 DFSN-diol 6

7 A 5 M NaH aqueous (80.2 ml) solution of potassium ferricyanide (9.67 g, 29.4 mmol) was added dropwise into 9-cyano-2-hydroxyl-methyl-fluorene (6) (5.90 g, 26.7 mmol) in methanol (210 ml) under water bath. The reaction mixture was allowed to stir for 5 min. After filtration of the reaction mixture, the crude product was washed with water and purified by silica gel column chromatography eluting with ethyl acetate / n-hexane (2/1) and reprecipitated from hexane. The obtained white powder was dried in vacuo at room temperature to give DFSN-diol as white powder (2.20 g, 37%). 1 H-NMR (500 MHz, DMS-d 6): δ/ppm (m, 7H, aromatic), 5.39 (br, 1H, -CH 2-H), 4.52 (br, 2H, -C-CH 2-H); 13 C NMR (125 MHz, DMS-d 6): δ/ppm , , , , , , , , , , , , 63.01, 53.20; FT-IR (K, cm 1 ): 3312, 3064, 2924, 2872, 2364, 2343, 2239, 1725, 1604, 1582, 1494, 1467, 1454, 1423, 1370, 1243, 1213, 1159, 1142, 1018, 954, 862, 830, 776, 750; FAB-MS (m/z): [M] + calcd. for C 30H 20N 2 2, ; Found, H 2 DMS c b a d e f g h i g, h c, d, e f, i a b d / ppm Figure S1. 1 H NMR spectrum of DFSN-diol (in DMS-d 6). 7

8 a DMS j,m o a o c ed b g f h i j k l n m e i h k l n g c b f,d d / ppm Figure S2. 13 C NMR spectrum of DFSN-diol (in DMS-d 6) Synthesis of DFSN-diacetyl (7) H H (CH 3 C) 2 TEA THF, r.t. DFSN-diol 7 To a solution of DFSN-diol (50 mg, mmol) and trimethylamine (0.126 ml, mmol) in THF (1 ml) was added dropwise acetic anhydride (4.3 µl, mmol) at 0 ºC. The reaction mixture was stirred at room temperature for 24 h and then poured into water. The reaction mixture was extracted with ethyl acetate, and the organic layer was washed with water and brine, dried over anhydrous MgS 4, and the solvent was removed to give DFSN-diacetyl (7) as white color solid (21 mg, 35%). 1 H-NMR (500 MHz, CDCl 3 ): δ/ppm (m, 7H, aromatic), (br, 2H, -C-CH 2-C()-), (s, 3H, -()C-CH 3); 13 C NMR (125 MHz, CDCl 3): , , , , , , , , , , , , , , , , , , , , 65.56, 65.46, 53.58, 20.98; FT-IR (K, cm 1 ): 3662, 3636, 3065, 2938, 2363, 2342, 2237, 1742, 1592, 1603, 1584, 1468, 1455, 1425, 1380, 1365, 1226, 1146, 1029, 972, 914,

9 2-7. Synthesis of bifunctional initiator DFSN-dibromide (8) H H TEA THF, r.t. DFSN-diol 8 To a solution of DFSN-diol (800 mg, 1.82 mol) and trimethylamine (2.53 ml, 18.2 mmol) in THF (20 ml) was added dropwise 2-bromoisobutyryl bromide (2.24 ml, 18.2 mmol) at 0 ºC. The reaction mixture was stirred at room temperature for 1 h and then poured into water. The reaction mixture was extracted with dichloromethane, and the organic layer was washed with water and brine, dried over anhydrous MgS 4, and the solvent was removed. The crude product was purified by silica gel column chromatography eluting with ethyl acetate / n-hexane (1/4). The solvent was removed and dried under vacuum to give DFSN-dibromide (8) as white solid (1.08 g, 81%). 1 H-NMR (500 MHz, CDCl 3 ): δ/ppm (m, 7H, aromatic), 5.12 (br, 2H, -C-CH 2- C()-), 1.96 (s, 6H, -C(CH 3) 2); 13 C NMR (125 MHz, CDCl 3): δ/ppm , , , , , , , , , , , , , , , , 65.86, 59.79, 54.32, 31.92; FT-IR (K, cm 1 ): 2358, 2339, 2238, 1817, 1786, 1736, 1711, 1692, 1583, 1466, 1454, 1427, 1389, 1371, 1270, 1157, 1107, 1010, 974, 837, 777, 750, Synthesis of TASN-dibromide (9) 4 Me Me H TEA H THF, r.t. Me Me TASN-diol 9 To a solution of TASN-diol (100 mg, mmol) which was prepared according to previous report 4 and trimethylamine (0.240 ml, 1.69 mmol) in THF (2 ml) was added dropwise 2- bromoisobutyryl bromide (0.208 ml, 1.69 mmol) at 0 ºC. The reaction mixture was stirred at room temperature for 1 h and then poured into water. The reaction mixture was extracted with dichloromethane, and the organic layer was washed with NaH aq. and brine, dried over anhydrous MgS 4, and the solvent was removed to give TASN-dibromide (9) as light yellow solid (124 mg, 82%). 1 H NMR (500 MHz, CDCl 3): δ/ppm (m, 8H, aromatic), (m, 8H, aromatic), (t, J = 6.1 Hz, 4H, --CH 2CH 2-), (t, J = 6.0 Hz, 4H, 9

10 CH 2CH 2-C()), 3.79 (s, 6H, -CH 3), 2.17 (quint, J = 6.1 Hz, 4H, -CH 2CH 2CH 2-), 1.93 (s, 12H, C(CH 3) 2); 13 C NMR (125 MHz, CDCl 3): δ/ppm , , , , , , , , , , 64.18, 62.71, 58.36, 55.78, 55.28, 30.73, 28.37; FT-IR (K, cm 1 ): 3748, 3674, 3002, 2959, 2934, 2838, 2364, 1734, 1607, 1580, 1509, 1464, 1419, 1389, 1371, 1299, 1257, 1186, 1108, 1033, 1011, 981, 922, 827, 781, 713, 679, 657, 625, 593, 580, 539, 494, 481, 471, 460, 452, 432, 418, Synthesis of PMMA-DFSN-PMMA 5 Me dnbpy, Cu anisole, 50 ºC Me n n Me 8 PMMA-DFSN-PMMA Methyl methacrylate (2.31 ml, 21.6 mmol), anisole (2.37 ml), 4,4 -dinonyl-2,2 -dipyridyl (dnbpy) (44.2 mg, 108 µmol) and 8 (40.0 mg, 54.2 µmol) were placed into a bottom flask. The mixture was bubbled with nitrogen for 30 min. Cu (15.5 mg, 108 µmol) was then added to the mixture, and the resulting solution was allowed to stir for 2 h at 50 ºC. The reaction was stopped by exposure to air at 0 C and dilution with CHCl 3. The solution was filtered through neutral alumina in order to remove the copper complex. After evaporation, concentrated solution was precipitated with methanol. The precipitate was collected by filtration and dried in vacuo to give PMMA-DFSN-PMMA as a white powder (426 mg, 59%). The M n and M w/m n values were determined by SEC with polystyrene standards. M n = g mol -1, M w/m n = 1.14; 1 H-NMR (500 MHz, CDCl 3 ): δ/ppm (br, aromatic), 4.96 (br, -C-CH 2-C()-), 3.60 (s, -CH 3), (m, -C(CH 3)-CH 2-C(CH 3)-), 1.02 (s, -CH 2-C(CH 3)-CH 2-), 0.85 (s, -CH 2-C(CH 3)-CH 2-). 10

11 e d c b i, j f g h i j k a a H 2 c b e, f, g h, k d CHCl 3 TMS d / ppm Figure. S3 1 H NMR spectrum of PMMA-DFSN-PMMA (in CDCl 3). M n = 13,200 M w /M n = Retention time / min Figure S4. SEC chart of PMMA-DFSN-PMMA. 11

12 2-10. ATRP of MMA initiated by TASN-dibromide Me Me Me dnbpy, Cu n 50 ºC Me 9 Me Me Methyl methacrylate (2.36 ml, 22.9 mmol), dnbpy (45.4 mg, 110 µmol), and TASN-dibromide (9) (49.4 mg, 55.5 µmol) were placed into a bottom flask. The mixture was bubbled with nitrogen for 30 min. Cu (15.9 mg, 110 µmol) was then added the mixture, and the resulting solution was allowed to stir for 2 h at 50 ºC. The reaction solution was filtered through neutral alumina in order to remove the copper complex. The M n and M w/m n values of the resulting solution was determined by SEC with polystyrene standards. n Me MMA M n = 2,850 M w /M n = 1.62 TASNdibromide Figure S5. SEC chart of the reaction solution of ATRP of MMA initiated by 9. 12

13 2-11. Exchange reaction between PMMA-DFSN-PMMA and excess DFSN Me n n Me anisole, 100 ºC n Me PMMA-DFSN-PMMA DFSN PMMA-DFSN-PMMA (20.0 mg, 1.49 µmol ), DFSN (29.3 mg, 76.9 µmol), anisole 2 ml were placed into a bottom flask. The mixture was bubbled with nitrogen for 30 min and the resulting solution was allowed to stir for 2 h at 110 ºC. The reaction was stopped by cooling at 0 C. The M n and M w/m n values before and after exchange reaction were determined by SEC with polystyrene standards. Before reaction M n = 13,800 g mol -1, M w/m n = 1.14, after reaction M n = 6,800 g mol -1, M w/m n = M n = 13,800 M w /M n = 1.14 M n = 6,800 M w /M n = Retention time / min Figure S6. SEC charts of before and after exchange reaction. 3. EPR Study (solution state) 3-1. EPR Study of DFSN (solution state) A 50 mm anisole solution of DFSN were charged in a 3 mm glass capillary with more than 43.5 mm height (the effective measuring range), and the capillary was sealed after being degassed. The spectra were measured using a microwave power of 0.15 mw and a field modulation 0.1 mt with a time constant of 0.03 s and a sweep rate of 0.25 mt/s. In variable temperature measurements from 90 to 130 C range, the spectra were measured after waiting for 3 min at each temperature. The concentration of the formed radicals was determined by comparing the area of 13

14 the observed integral spectrum with a 0.06 mm solution of 4-hydroxy-2,2,6,6- tetramethylpiperidin-1-oxyl (TEMPL) in the same solvent under the same experimental conditions. The Mn 2+ signal was used as an auxiliary standard. The g value was calculated according to the following equation: g = hν/βh where h is the Planck constant, ν is the microwave frequency, β is the Bohr magneton and H is the magnetic field. The ratio of dissociated DFSN was calculated from the peak intensity using TEMPL as a standard. a Dissociation ratio / 10-4 % DFSN TASN Temperature / ºC b Figure S7. (a) Dissociation ratio of DFSN and TASN in EPR measurements at various temperatures. (b) Photographs of heating TASN (50 mm in anisole) at 100 ºC EPR study of DFSN-diacetyl (7) (solution state) A 50 mm anisole solution of DFSN-diacetyl (7) were charged in a 3 mm glass capillary with more than 43.5 mm height (the effective measuring range), and the capillary was sealed after being degassed. The spectra were measured using a microwave power of 0.7 mw and a field modulation 0.6 mt with a time constant of 0.03 s and a sweep rate of 0.25 mt/s. In variable temperature measurements from 70 to 130 C range, the spectra were measured after waiting for 3 min at each temperature. The ratio of dissociated DFSN-diacetyl (7) was calculated from the peak intensity using TEMPL as a standard. van't Hoff plot was prepared, and the bond dissociation enthalpy (ΔH) and entropy (ΔS) were calculated from the following equation: lnk = ΔH/RT + ΔS/R where R is the gas constant and T is the measurement temperature. 14

15 g = ºC 120 ºC 110 ºC 100 ºC 90 ºC 80 ºC 70 ºC Magnetic field / mt Figure S8. EPR spectra of 7 in anisole at various temperatures. Figure S9. van t Hoff plot for the dissociation of 7. Table S1. Bond dissociation enthalpy and entropy of 7. DH DS (kj/mol) (J/K mol)

16 4. Grinding tests and EPR study (solid state) Grinding tests of DFSN, DFSN-diol and PMMA-DFSN-PMMA were performed on a Retsch Mixer Mill MM 400 and the same conditon. The mechanical energy was controlled by vibrational frequency and grinding time. A powdered sample (50 mg) was placed in the grinding jar and ground for 5 min at 30 Hz. The ground samples were transferred into an EPR glass capillary, weighed and the capillary was sealed after being degassed. EPR measurements were carried out on a JEL JES-X320 X-band EPR spectrometer equipped with a JEL DVT temperature controller. The spectra of ground samples were measured using a microwave power of 0.1 mw and a field modulation of 0.1 mt with a time constant of 0.03 s and a sweep rate of 0.25 mt/s at 25 C. The concentration of the radicals formed from the cleavage of DFSN-diol and PMMADFSN-PMMA were determined by comparing the area of the observed integral spectrum with a 0.06 mm solution of TEMPL in the benzene under the same experimental conditions. In a similar manner, PMMA-DFSN-PMMA heated by 150 ºC was also measured. a Grinding b Grinding Figure S10. (a) The photographs of DFSN before and after grinding, (b) the photographs of DFSNdiol before and after grinding. 16

17 Figure S11. (a) EPR spectra of DFSN (black) and DFSN after grinding (red). (b) EPR spectra of PMMA-DFSN-PMMA after grinding (pink) and after heating at 150 ºC (black). 17

18 5. Recombination of the carbon radicals generated from PMMA-DFSN-PMMA Figure S12. The photographs of the color change of the ground PMMA-DFSN-PMMA before and after the addition of THF. 6. References (1) Hou, X.; Ge, Z.; Wang, T.; Guo, W.; Wu, J.; Cui, J.; Lai, C.; Li, R. Synthesis and Structure- Activity Relationships of A Novel Class of Dithiocarbamic Acid Esters as Anticancer Agent. Arch. Pharm. (Weinheim). 2011, 344, (2) Du, Y.; Chang, J.; Reiner, J. Formation of N -Alkoxyindole Framework : Intramolecular Heterocyclization of 3-Alkoxyimino-2-Arylalkylnitriles Mediated by Ferric Chloride Recei V Ed No V Ember 15, 2007 A Variety of Functionalized N-Alkoxyindole-3- Carbonitrile Derivatives Are Achieved. 2010, 51, (3) Drouet, S.; Paul-Roth, C..; Simonneaux, G. Synthesis and Photophysical Properties of Porphyrins with Fluorenyl Pendant Arms. Tetrahedron 2009, 65 (15), (4) Sumi, T.; Goseki, R.; tsuka, H. Tetraarylsuccinonitriles as Mechanochromophores to Generate Highly Stable Luminescent Carbon-Centered Radicals. Chem. Commun. 2017, 53, (5) Matyjaszewski, K.; Xia, J. Atom Transfer Radical Polymerization. Chem. Rev. 2001, 101,