Supporting Information Fluorescent Photochromic Diarylethene That Turns on with Visible Light Takaki Sumi, Tomohiro Kaburagi, Masakazu Morimoto, Kanako Une, Hikaru Sotome, Syoji Ito, Hiroshi Miyasaka, and Masahiro Irie *, Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan S1
1. Experimental Section 1-1. General Commercially available reagents and solvents used for syntheses were of reagent grade and used without further purification. Solvents used for spectroscopic measurements were of spectroscopic grade. 1 H and 13 C NMR spectra were recorded with an NMR spectrometer (Bruker Biospin, Avance 400). Tetramethylsilane (TMS) was used as an internal standard. Mass spectra were recorded with a mass spectrometer based on electron impact (EI) ionization method (Shimadzu, GCMS-QP2010Plus) and a time-of-flight mass spectrometer based on direct-analysis-in-real-time (DART) ionization method (JEOL, JMS-T100LP). X-ray crystallographic analysis was performed with a CCD-based X-ray diffractometer (Bruker AXS, SMART APEX2 Ultra-Cu) with Cu K radiation ( = 1.54178 Å). The crystal was cooled using a low temperature controller (Japan Thermal Engineering, TC-190CP-CS-K). The diffraction frames were integrated with the Bruker SAINT program. The cell constants were determined by the global refinement. The structure was solved by the direct method using the SHELXS-97 program and refined by the full-matrix least-squares method using the SHELXL-2014 program. The positions of all hydrogen atoms were calculated geometrically and refined by the riding model. Crystallographic data in this paper can be obtained free of charge from at the Cambridge Crystallographic Data Centre under a reference numbers CCDC 1400016 (1cis) and 1400017 (1c). Absorption spectra were recorded with an absorption spectrophotometer (Hitachi, U-4100). Fluorescence spectra were recorded with a fluorescence spectrophotometer (Hitachi, F-2500) and no correction was performed for the spectra. Fluorescene quantum yields were measured by an absolute PL quantum yield measurement system (Hamamatsu Photonics, C9920-02G). Fluorescence dynamics was measured by a time-correlated single-photon-counting (TCSPC) system. Experimental setup for the TCSPC was described previously S1. The light source was a Ti:sapphire laser (Spectra Physics, Tsunami) the operating wavelength, pulse duration, and repetition rate of which were respectively 860 nm, 70 fs, and 80 MHz. The samples in 1-cm quartz cells were photoexcited with the second harmonic (430 nm) of the fundamental output of the laser generated in a type I BBO crystal. The repetition rate was reduced to 8 MHz by using an electro-optic modulator (Conoptics, Model 350) and an input power to the cells were typically 0.3 µw at 8 MHz. The detection of the fluorescence at the magic angle configuration was attained by utilizing a film polarizer and Babinet-Soleil compensator. The emission band at 505-515 nm was detected using a photomultiplier-tube (Hamamatsu Photonics, R3809U-50) with a pre-amplifier (Hamamatsu Photonics, C5594) and a time-correlated single-photon counting S2
(TCSPC) module (PicoQuant, PicoHarp 300). For the wavelength selection a monochromator (Princeton Instruments, Acton 2150) was placed in front of the photomultiplier-tube. The typical response time of the system was determined to be 32 ps full-width-at-half-maximum by detecting scattered photons from a colloidal solution. Photoirradiation was carried out using a 300 W xenon lamp (Asahi spectra, MAX-303). Wavelength of the light was selected using a monochrometer (Ritsu, MC-10N) and band-pass or cut-off optical filters. The photogenerated isomers were isolated from a UV-irradiated solution of 1 by using HPLC (Hitachi, pump system L-2130, UV-Vis detector L-2420, Wakosil 5SIL 4.6 mm 250 mm, hexane : ethyl acetate = 85 : 15, 1 ml/min, 313 nm). S3
1-2. Synthesis Scheme S1. Synthesis of 1. 1,2-Dicyano-1,2-bis(2-ethyl-6-phenyl-1-benzothiophen-3-yl)ethene (3) To an acetic acid solution (500 ml) of 2 (6.8 g, 17 mmol) was added conc. H 2 SO 4 (10 ml), water (20 ml), iodine (5.4 g, 21 mmol), and orthoperiodic acid (1.6 g, 7.0 mmol). The mixture was stirred vigorously at 75 C for 3 h and then poured into ice water. Precipitates were collected by filtration and washed with aqueous NaHCO 3, aqueous Na 2 S 2 O 3, water, and a small amount of methanol. Yellow powders obtained (6.5 g) were found to be a mixture containing not only diiodide, 1,2-Dicyano-1,2-bis(2-ethyl-6-iodo-1-benzothiophen- 3-yl)ethane (MS (EI) m/z = 650 [M] + ; 55 mol%) but also monoiodide (35 mol%) and triiodide (10 mol%) according to mass spectrometry and used for the next Suzuki-Miyaura coupling reaction without further purification. To a THF solution (500 ml) of the yellow powders (4.0 g) containing diiodide (2.5 g, 3.8 mmol) was added phenylboronic acid (3.6 g, 30 mmol), an aqueous solution (80 ml) of Na 2 CO 3 (15 g), and tetrakis(triphenylphosphine)palladium(0) (1.05 g, 0.91 mmol), and the mixture was refluxed for 16 h. The mixture was poured into water and extracted with chloroform. The organic layer was dried over MgSO 4, filtrated, and concentrated. The residue was purified by silica gel column chromatography (hexane : chloroform = 1 : 1) and gel permeation chromatography (GPC) (Japan Analytical Industry, GPC system LC-908, Jaigel-2H 20 mm 600 mm and Jaigel-2.5H 20 mm 600 mm, chloroform, 3.5 ml/min) to afford 3 as yellow powders (0.65 g, 1.2 mmol, 32% base on diiodide). Mp 233-234 C; 1 H NMR (400 MHz, CDCl 3, TMS) 0.77 (s, br, 3H), 1.26 (s, br, 3H), 2.19 (m, br, 1H), 2.61 (m, br, 2H), 2.96 (m, br, 1H), 7.40-7.95 (m, 16H); 13 C NMR (100 S4
MHz, CDCl 3, TMS) 14.6, 15.0, 77.4, 115.9, 120.7, 121.0, 121.5, 121.7, 122.3, 122.9, 124.6, 125.0, 127.3, 127.7, 129.0, 135.0, 136.0, 138.1, 138.4, 138.5, 140.3, 152.0, 152.8; HRMS (DART) m/z [M+NH 4 ] + Calcd for C 36 H 26 N 2 S 2 : 568.1881; Found: 568.1898. 1,2-Dicyano-1,2-bis(2-ethyl-6-phenyl-1-benzothiophene-1,1-dioxide-3-yl)ethene (1) To a dichloromethane solution (15 ml) of 3 (0.32 g, 0.58 mmol) was added a dichloromethane solution (15 ml) of m-chloroperbenzoic acid (2.5 g, 14 mmol) which was dried over MgSO 4 before use, and the mixture was stirred for 24 h. The mixture was neutralized with aqueous NaHCO 3, washed with aqueous Na 2 S 2 O 3, and extracted with chloroform. The organic layer was dried over MgSO 4, filtrated, and concentrated. The residue was purified by silica gel column chromatography (hexane : ethyl acetate = 7 : 3), GPC (Japan Analytical Industry, GPC system LC-908, Jaigel-2H 20 mm 600 mm and Jaigel-2.5H 20 mm 600 mm, chloroform, 3.5 ml/min, 313 nm), and HPLC (Hitachi, pump system L-2130, UV-Vis detector L-2420, Wakosil 5SIL 20 mm 250 mm, hexane : ethyl acetate = 85 : 15, 20 ml/min, 313 nm) to afford 1 as pale yellow powders (0.10 g, 0.16 mmol, 28%). Mp 225-227 C; 1 H NMR (400 MHz, CDCl 3, TMS) 0.88 (t, br, J = 6.8 Hz, 2H), 1.26 (t, br, J = 7.0 Hz, 4H), 2.91 (m, br, 4H), 7.45-7.54 (m, 8H), 7.63 (d, J = 8.0 Hz, 4H), 7.91 (dd, J = 8.0 and 1.6 Hz, 2H), 8.09 (d, J = 1.6 Hz, 2H); 13 C NMR (100 MHz, CDCl 3, TMS) 11.6, 19.3, 30.9, 77.2, 112.3, 121.4, 127.07, 127.16, 129.2, 129.4, 132.7, 136.5, 138.1, 145.0. HRMS (DART) m/z [M+NH 4 ] + Calcd for C 36 H 26 O 4 N 2 S 2 : 632.1678; Found: 632.1682. S5
1trans Time / min 1cis Figure S1. HPLC chromatogram for 1 after irradiation with UV light. Pump system: Hitachi L-2130, UV-Vis detector: Hitachi L-2420, column: Wakosil 5SIL 4.6 mm 250 mm, solvent: hexane : ethyl acetate = 85 : 15, flow: 1 ml/min, detection: 313 nm. 1c S6
(a) (b) Figure S2. 1 H NMR (400 MHz, CDCl 3, TMS) (a) and 13 C NMR (100 MHz, CDCl 3, TMS) (b) spectra of 3. S7
(a) (b) Figure S3. 1 H NMR (400 MHz, CDCl 3, TMS) (a) and 13 C NMR (100 MHz, CDCl 3, TMS) (b) spectra of 1. S8
2. X-ray crystallographic analysis Table S1. Crystal data for 1cis and 1c. 1cis 1c formula C 36 H 26 N 2 O 4 S 2 C 36 H 26 N 2 O 4 S 2 formula weight 614.71 614.71 T / K 93(2) 93(2) crystal system triclinic triclinic space group P-1 P-1 a / Å 10.9720(3) 7.8828(2) b / Å 11.3560(3) 13.6596(3) c / Å 12.6933(3) 14.9014(3) / 105.7500(10) 112.8251(10) / 96.5090(10) 96.4272(11) / 100.3480(10) 96.2488(13) V / Å 3 1475.31(7) 1449.13(6) Z 2 2 R 1 (I > 2 (I)) 0.0392 0.0421 wr 2 (I > 2 (I)) 0.0408 0.0457 R 1 (all data) 0.1073 0.1177 wr 2 (all data) 0.1090 0.1215 CCDC No. 1400016 1400017 S9
3. Measurement of photoreaction quantum yields A 1,4-dioxane solution containing 1cis or 1trans was irradiated with 313 nm light and the concentration changes of 1cis, 1trans, and 1c were monitored by HPLC (Hitachi, pump system L-2130, UV-Vis detector L-2420, Wakosil 5SIL 4.6 mm 250 mm, hexane : ethyl acetate = 85 : 15, 1 ml/min, 313 nm), as shown in Figure S1. The time course of the contents of the three isomers shown in Figure 4 in the main manuscript was analyzed by using the following differential equations. dc cis dt dc close dt dc trans dt = I 0 V [{Φ close cis (1 10 ( C closeε irr close ) )} + {Φ trans cis (1 10 ( C irr transε trans {Φ cis close (1 10 ( C cisε irr) cis )} {Φ cis trans (1 10 ( C cisε irr) cis )}] = I 0 V [ {Φ close cis(1 10 ( C closeε irr close = I 0 V [ {Φ trans cis (1 10 ( C irr transε trans ) )} ) )} + {Φ cis close (1 10 ( C cisε irr) cis )}] ) )} + {Φ cis trans (1 10 ( C cisε irr) cis )}] In the above equations C trans, C cis, and C close are the concentrations of 1trans, 1cis, and 1c, respectively. I 0 is the intensity of 313 nm light. trans-cis, cis-trans, cis-close, and close-cis are the photoreaction quantum yields of 1trans to 1cis, 1cis to 1trans, 1cis to 1c, and 1c to 1cis, respectively. trans, cis, and close are the molar absorption coefficients of 1trans, 1cis, and 1c at 313 nm, respectively. I 0 was measured by using a hexane solution of 1,2-bis(2-methyl-1-benzothiophen-3-yl)perfluorocyclopentene S2 as a chemical actinometer. cis was directly measured by using 1cis isolated by HPLC. close was determined by comparing the absorption spectrum of 1c isolated by HPLC with that of 1cis prepared by irradiation to the solution of 1c with visible light ( > 480 nm). trans was determined by comparing the absorption spectrum of 1trans isolated by HPLC with that of 1c prepared by prolonged irradiation to the solution of 1trans with 313 nm light (the photoconversion percentage to 1c is ~100%). According to the differential equations numerical simulations were carried out for the experimental data shown in Figure 4. The best-fit curves are also shown in the figure. trans-cis, cis-trans, cis-close, and close-cis were determined to be 0.34, 0.55, 0.28, and 1.7 10 4, respectively. S10
4. The changes in the contents of 1cis, 1trans and 1c upon irradiation with 405 nm light Figure S4. The changes in the contents of 1cis (black circles), 1trans (open circles) and 1c (red circles) upon irradiation with 405 nm light started from (a) 1cis and (b) 1trans. S11
5. Reference (S1) Nagasawa, Y.; Itoh, T.; Yasuda, M.; Ishibashi, Y.; Ito, S.; Miyasaka, H. J. Phys. Chem. B 2008, 112, 15758-15765. (S2) Sumi, T.; Takagi, Y.; Yagi, A.; Morimoto, M.; Irie, M. Chem. Commun. 2014, 50, 3928-3930. S12