Supporting Information. (Z)-1,2-Di(1-pyrenyl)disilene: Synthesis, Structure, and Intramolecular Charge-Transfer Emission

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1 Supporting Information (Z)-1,2-Di(1-pyrenyl)disilene: Synthesis, Structure, and Intramolecular Charge-Transfer Emission Megumi Kobayashi, Naoki Hayakawa, Tsukasa Matsuo,*,,, Baolin Li, Takeo Fukunaga, Daisuke Hashizume, Hiroyuki Fueno, # Kazuyoshi Tanaka, # and Kohei Tamao*, Functional Elemento-Organic Chemistry Unit, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama , Japan Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Kowakae, Higashi-Osaka JST, PRESTO, Honcho Kawaguchi, Saitama Materials Characterization Support Unit, RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama # Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto , Japan t-matsuo@apch.kindai.riken.jp (submitted to J. Am. Chem. Soc.) Contents 1. Experimental Procedures S2 2. X-ray Crystallographic Analysis S8 3. Photophysical Data S11 4. Theoretical Calculations S14 5. References S42 S1

2 1. Experimental Procedures General Procedures. All manipulations of air- and/or moisture-sensitive compounds were performed either using standard Schlenk-line techniques or in a glove box under an inert atmosphere of argon. Anhydrous hexane, benzene, toluene, diethyl ether (Et 2 O), and tetrahydrofuran (THF) were dried by passage through columns of activated alumina and supported copper catalyst supplied by Hansen & Co., Ltd. Anhydrous pentane was purchased from Kanto Chemical Co., Inc. and used without further purification. Deuterated benzene (benzene-d 6, C 6 D 6 ) was dried and degassed over a potassium mirror in vacuo prior to use. (1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen- 4-yl)silane (Eind)SiH3 was prepared by the literature procedures. S1 Other chemicals and gases were used as received. The nuclear magnetic resonance (NMR) measurements were carried out on JEOL ECS-400 spectrometer (399.8 MHz for 1 H, MHz for 13 C, and 79.4 MHz for 29 Si). Chemical shifts ( ) are given by definition as dimensionless numbers and relative to 1 H and 13 C NMR chemical shifts of the solvent (residual C 6 D 5 H in C 6 D 6, 1 H( ) = 7.15 and 13 C( ) = 128.0). The 29 Si NMR spectra were referenced using external standard of tetramethylsilane ( 29 Si( ) = 0.0). The absolute values of the coupling constants are given in Hertz (Hz), regardless of their signs. Multiplicities are abbreviated as singlet (s), doublet (d), triplet (t), quartet (q), multiplet (m), and broad (br). The UV-vis spectra were obtained using a Shimadzu UV-3101(PC)S spectrometer. The fluorescence spectra were measured by a JASCO FP-6500 spectrofluorometer. The elemental analyses (C and H) and mass spectrometry were performed at the Advanced Technology Support Division of RIKEN Advanced Science Institute (Materials Characterization Support Unit, RIKEN Center for Emergent Matter Science). We believe that on the basis of the NMR spectra and the X-ray crystal structure the compounds are authentic and analytically pure but their incomplete combustion might be responsible for the incorrect elemental analysis. Melting points (mp) were determined by a Stanford Research Systems OptiMelt instrument. S2

3 Synthesis of tribromo(1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl)silane [(Eind)SiBr 3 ] (3). To a solution of (Eind)SiH3 (3.31 g, 8.02 mmol) in hexane (60 ml) was added N-bromosuccinimide (NBS) (4.61 g, 25.9 mmol) at 0 ºC. The reaction mixture was warmed up to room temperature and stirred for overnight. After the solvent was removed in vacuo, the suspension was centrifuged to remove an insoluble material. The supernatant was concentrated, and the residual solid was recrystallized from hexane to afford 3 as colorless crystals (3.87 g, 5.97 mmol, 74%). Analytical data were identical to the reported values. S2 Synthesis of dibromo(1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl)- (1-pyrenyl)silane [(Eind)(1-Pyrenyl)SiBr 2 ] (4). To a Et 2 O (20 ml) solution of 1-bromopyrene (564 mg, 2.01 mmol) was added t-buli (1.77 M solution in pentane, 2.30 ml, 4.07 mmol) at 80 ºC. After stirring for 30 min at 80 ºC, the reaction mixture was allowed to warm up to room temperature. To a solution of 3 (1.34 g, 2.06 mmol) in Et 2 O (20 ml) was added the resulting Et 2 O solution of 1-lithiopyrene at 80 C. The mixture was allowed to warm up to room temperature and was stirred for overnight. After the solvent was removed in vacuo, to the residue was added toluene (40 ml) and the suspension was centrifuged to remove an insoluble material. The supernatant was concentrated, and the residual solid was washed with a small amount of hexane to afford 4 as a colorless solid (543 mg, 0.70 mmol, 36%): mp (argon atmosphere in a sealed tube) C (dec). 1 H NMR (C 6 D 6 ) 0.56 (t, J = 7.3 Hz, 6 H, Me), 0.80 (t, J = 7.3 Hz, 6 H, Me), 0.81 (t, J = 7.3 Hz, 6 H, Me), 0.87 (t, J = 7.1 Hz, 6 H, Me), (m, 8 H + 4 H, CH 2 ), (m, 2 H, CH 2 ), (m, 2 H, CH 2 ), (m, 2 H, CH 2 ), (m, 2 H, CH 2 ), 6.97 (s, 1 H, ArH), 7.66 (t, J = 7.6 Hz, 1 H, ArH), (m, 3 H, ArH), 7.80 (d, J = 7.8 Hz, 1 H, ArH), 7.84 (d, J = 7.8 Hz, 1 H, ArH), 7.95 (d, J = 7.8 Hz, 1 H, ArH), 8.47 (d, J = 9.1 Hz, 1 H, ArH), 8.88 (d, J = 7.7 Hz, 1 H, ArH); 13 C NMR (C 6 D 6 ) 9.2, 9.3, 10.0, 10.8, 32.5, 33.6 ( 2), 34.2, 43.5, 47.9, 55.1, 124.6, 124.7, 125.1, 125.3, 126.0, 126.1, 126.4, 128.5, 128.8, 129.1, 130.8, 131.4, 131.7, 133.4, 134.6, 136.1, 137.8, 151.5, (one aromatic peak is overlapped); 29 Si NMR (C 6 D 6 ) 7.82 (d, J = 9.3 Hz). HRMS (ESI, positive) Calcd for C 44 H 54 Br 2 Si+Na: Found: S3

4 Synthesis of (Z)-1,2-bis(1-pyrenyl)-1,2-bis(1,1,3,3,5,5,7,7-octaethyl-shydrindacen-4-yl)disilene ((Z)-2). To a solution of 4 (299 mg, 0.39 mmol) in THF (10 ml) was added a solution of lithium naphthalenide (1.31 mmol) in THF (5 ml) at 90 ºC. After stirring for 30 min at 90 ºC, the reaction mixture was allowed to warm up to room temperature. After the reaction mixture was stirred for overnight, the solvent was removed in vacuo. To the residue was added toluene (40 ml) and the suspension was centrifuged to remove an insoluble material. The supernatant was concentrated, and the residual solid was washed with a small amount of pentane to afford (Z)-2 as a purple powder (102 mg, 83.1 mol, 43%). 1 H NMR (C 6 D 6 ) 0.18 (t, J = 7.1 Hz, 6 H, Me), 0.70 (t, J = 7.3 Hz, 6 H, Me), 0.78 (t, J = 7.3 Hz, 6 H, Me), (m, 18 H, Me), 0.87 (t, overlapped, 12 H, Me), (m, 16 H + 8 H, CH 2 ), (m, 4 H, CH 2 ), (m, 2 H, CH 2 ), (m, 4 H, CH 2 ), (m, 2 H, CH 2 ), (m, 2 H, CH 2 ), (m, 2 H, CH 2 ), 6.81 (d, J = 9.1 Hz, 2 H, ArH), 6.90 (s, 2 H, ArH), 7.19 (d, J = 8.7 Hz, 2 H, ArH), (m, 6 H, ArH), 7.42 (d, J = 8.7 Hz, 2 H, ArH), 7.85 (d, J = 8.3 Hz, 2 H, ArH), 8.24 (d, J = 9.2 Hz, 2 H, ArH), 8.59 (d, J = 7.8 Hz, 2 H, ArH); 13 C NMR (C 6 D 6 ) 9.26 ( 2), 9.33, 9.4, 9.9, 10.3, 11.8, 12.0, 31.5, 31.9, 33.4 ( 2), 33.6, 35.2, 36.5, 37.6, 40.9, 45.5, 47.2, 47.8, 53.8, 54.1, 121.9, 123.5, 123.9, ( 2), 124.8, 124.9, 125.3, 126.0, 126.3, 128.2, 129.5, 129.8, 132.2, , 135.3, 149.4, 150.0, 156.2, (one aromatic peak is overlapped); 29 Si NMR (C 6 D 6 ) UV-vis (THF) max ( ) = 519 nm (sh, ), 575 nm ( ). HRMS (ESI, positive) Calcd for C 88 H 108 Si 2 : Found: S4

5 Synthesis and Purification of (Z)-1,2-bis(1-pyrenyl)-1,2-bis(1,1,3,3,5,5,7,7- octaethyl-s-hydrindacen-4-yl)disilene ((Z)-2). In the dark, to a solution of 4 (303 mg, 0.39 mmol) in THF (10 ml) was added a solution of lithium naphthalenide (1.40 mmol) in THF (5 ml) at 90 ºC. After stirring for 30 min at 90 ºC, the reaction mixture was allowed to warm up to room temperature. After the reaction mixture was stirred for overnight, the solvent was removed in vacuo. To the residue was added toluene (40 ml) and the suspension was centrifuged to remove an insoluble material. The supernatant was concentrated, and the residual solid was washed with a small amount of cold pentane to afford (Z)-2 as a purple solid (91 mg, 74.1 mol, 38%). The resulting solid was recrystallized from benzene at ambient temperature to afford purple crystals (38 mg, 31.4 mol, 8%). For the photophysical measurements, the obtained crystals were further heated at 60 ºC for 1 day under high vacuum ( mbar) to remove a trace amount of naphthalene. S5

6 Figure S1. 1 H NMR spectrum of (Z)-2 in C 6 D 6. S6

7 Figure S2. 29 Si NMR spectrum of (Z)-2 in C 6 D 6. S7

8 2. X-Ray Crystallographic Analysis Crystal structure analysis of (Z)-2. Crystallographic data are summarized in Table S1. X-ray quality single crystals were obtained from benzene for (Z)-2 as purple platelets. A single crystal of (Z)-2 was immersed in oil (Immersion Oil, type B: Code 1248, Cargille Laboratories, Inc.) and mounted on a MicroMount TM (MiTeGen, LLC) and mounted on a Rigaku AFC-8 diffractometer with Saturn70 CCD detector. The diffraction data were collected using MoK radiation ( = Å), which was monochromated by a multi-layered confocal mirror. The specimens were cooled at 90 K in a cold nitrogen stream during the measurements. Bragg spots were integrated and scaled with the programs of HKL2000. S3 Then, intensities of the equivalent reflections merged for structure analysis. Structure was solved by a direct method with the program of SIR2004 S4, and refined on F 2 by a full-matrix least-squares method using the SHELXL-97 program. S5 Anisotropic atomic displacement parameters were applied to all non-hydrogen atoms. The hydrogen atoms were put at calculated positions, and refined by applying riding models. The detailed crystallographic data have been deposited with the Cambridge Crystallographic Data Centre: Deposition code CCDC ((Z)-2). A copy of the data can be obtained free of charge via S8

9 Table S1. Crystallographic data for (Z)-2 formula C 88 H 108 Si 2 FM T/K 90 wavelength/å (MoK ) color purple crystal size, mm 0.13 x 0.10 x 0.02 crystal system monoclinic space group P2 1 /n (# 14) a/å (2) b/å (2) c/å (3) /º 90 /º (5) /º 90 V/Å (15) Z 4 D x / g cm (Mo-K )/ mm reflections collected unique reflections refined parameters 894 GOF on F R1 [I > 2 (I)] a wr2 (all data) b min, max /e Å , a R(F) = Fo - Fc / Fo, b wr(f 2 ) = ( (w(fo 2 Fc 2 ) 2 / w(fo 2 ) 2 ) 1/2 S9

10 Figure S3. Molecular structures of (Z)-2 (50% probability ellipsoids): top view (top) and front view (bottom). Hydrogen atoms and disordered ethyl groups are not shown. Selected atomic distances (Å), bond angles (deg), and torsion angles (deg): Si1 Si2 = (6), Si1 C1 = (14), Si1 C57 = (14), Si2 C29 = (14), Si2 C73 = (15), C57 C73 = 3.636(2), C64 C80 = 4.036(3), a distance between the two pyrene ring centers (purple dotted line) = 3.635, C1 Si1 Si2 = (5), C1 Si1 C57 = (6), C57 Si1 Si2 = (6), C29 Si2 Si1 = (5), C29 Si2 C73 = (7), C73 Si2 Si1 = (5), Si2 Si1 C57 C70 = 52.66(13), Si1 Si2 C73 C86 = 48.73(14). S10

11 3. Photophysical Data UV-visible spectra of (Z)-2 were obtained on Shimadzu UV-3101(PC)S spectrometer with a resolution of 0.5 nm (Figure S4). Ca M of a sample solution in a 1 cm square quartz cell was used for room temperature measurement. Dry hexane, THF (purchased from Kanto Chemical Co., Inc.) and acetone (purchased from Wako Pure Chemical Industries, Ltd.) were used for the sample solution. Fluorescence spectra were measured by JASCO FP-6500 spectrofluorometer under irradiation at 365 nm, thus the spectral region more than 400 nm is shown in Figures S4 and S7. Weak emission of pyrene excimer were also observed around 450 nm due to partial decomposition of (Z)-2 during the measurements of emission spectra. Absolute fluorescence quantum yields were measured by a calibrated integrating sphere system C10027 (Hamamatsu Photonics). Figure S4. UV-vis absorption and fluorescence spectra of (Z)-2 in THF at ambient temperature. S11

12 Figure S5. Photographs of (Z)-2 at ambient temperature. (left) solid in the air, (right) solid under irradiation at 365 nm. Figure S6. Photographs of (Z)-2 at ambient temperature. (left) solution in THF, (right) solution in THF under irradiation at 365 nm. S12

13 Figure S7. Emission spectra of (Z)-2 in solvents of different polarities: blue in hexane; red in THF; green in acetone. Figure S8. Photographs showing the effect of solvent polarity on the emission color of (Z)-2 when excited by 365 nm light: (left to right) hexane, THF, and acetone. S13

14 4. Theoretical Calculations The geometry optimizations of (E)-1, S1 (Z)-1, (E)-2, and (Z)-2 were performed at the B3LYP/6-31G(d,p) level of theory using Gaussian 09 program package. S6 The optimized structures in the ground state are shown in Figures S9, S10, S12, and S13. The patterns of selected molecular orbitals of (E)-1 and (Z)-2 are shown in Figures S11 and S14. The optimized structures of (E)-2 and (Z)-2 in the ground state have also been examined using the hybrid B3LYP and the long-range correction by the Coulombattenuating method (CAM) S7 at the CAM-B3LYP/6-31G(d,p) level (Figures S15 and S16). The patterns of selected molecular orbitals of (Z)-2 are shown in Figure S17. We also examined the optimized structures of the isomers of 2 using the semiempirical generalized gradient approximation (GGA) type density functional constructed with a long-range dispersion correction at the B97-D/6-31G(d,p) level (Figures S18 and S19). S8 The patterns of selected molecular orbitals of (Z)-2 are shown in Figure S20. The structural data for (Z)-2 are summarized in Table S2. Relative energies (kcal mol 1 ) of 1 and 2 are summarized in Figures S21 S24. We also performed the geometry optimization of (Z)-2 in the first excited singlet state at the TD-B3LYP/6-31G(d,p) and TD CAM-B3LYP/6-31G(d,p) levels. The optimized structures in the first excited singlet state are shown in Figures S25 and S26. The structural data for (Z)-2 in the first excited singlet state are also summarized in Table S2. The Wiberg bond index (WBI) S9 and natural population analysis (NPA) S10 charge distribution of (Z)-2 were calculated by natural bond orbital method at the TD-B3LYP/6-31G(d,p) and TD CAM-B3LYP/6-31G(d,p) levels (Figures S27 S30). The absorption wavelengths of (Z)-2 were calculated at the ground state geometry using TD-B3LYP/6-31G(d,p) and TD CAM-B3LYP/6-31G(d,p) methods (Figures S31 and S32 and Tables S3 and S4). The emission wavelengths of (Z)-2 were calculated by means of the computations of the absorption wavelengths of the optimized excited state structure as a ground state (Figures S33 and S34 and Tables S5 and S6). Figures S31 S34 were drawn by using GaussView software. S11 S14

15 Figure S9. Calculated structures of (E)-1 in the ground state (C 2 symmetry) at the B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C29 = , C1 Si1 Si1* = , C29 Si1 Si1* = , C1 Si1 C29 = , Si1* Si1 C29 C30 = S15

16 Figure S10. Calculated structures of (Z)-1 in the ground state (C 2 symmetry) at the B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C29 = , C1 Si1 Si1* = , C29 Si1 Si1* = , C1 Si1 C29 = , Si1* Si1 C29 C30 = S16

17 Figure S11. Selected molecular orbitals of (E)-1 (top view) at the B3LYP/6-31G(d,p) level, together with the energy levels (ev). S17

18 Figure S12. Calculated structures of (E)-2 in the ground state (C i symmetry) at the B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C29 = , C1 Si1 Si1* = , C29 Si1 Si1* = , C1 Si1 C29 = , Si1* Si1 C29 C30 = S18

19 Figure S13. Calculated structures of (Z)-2 in the ground state (C 1 symmetry) at the B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C57 = , Si2 C29 = , Si2 C73 = , C57 C73 = , C64 C80 = , a distance between the two pyrene ring centers = , C1 Si1 Si2 = , C57 Si1 Si2 = , C1 Si1 C57 = , C29 Si2 Si1 = , C73 Si2 Si1 = , C29 Si2 C73 = , Si2 Si1 C57 C70 = 58.92, Si1 Si2 C73 C86 = S19

20 Figure S14. Selected molecular orbitals of (Z)-2 (top view) at the B3LYP/6-31G(d,p) level, together with the energy levels (ev). S20

21 Figure S15. Calculated structures of (E)-2 in the ground state (C i symmetry) at the CAM-B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C29 = , C1 Si1 Si1* = , C29 Si1 Si1* = , C1 Si1 C29 = , Si1* Si1 C29 C30 = S21

22 Figure S16. Calculated structures of (Z)-2 in the ground state (C 1 symmetry) at the CAM-B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C57 = , Si2 C29 = , Si2 C73 = , C57 C73 = , C64 C80 = , a distance between the two pyrene ring centers = , C1 Si1 Si2 = , C57 Si1 Si2 = , C1 Si1 C57 = , C29 Si2 Si1 = , C73 Si2 Si1 = , C29 Si2 C73 = , Si2 Si1 C57 C70 = 55.54, Si1 Si2 C73 C86 = S22

23 Figure S17. Selected molecular orbitals of (Z)-2 (top view) at the CAM-B3LYP/6-31G(d,p) level, together with the energy levels (ev). S23

24 C30* C1 C29 Si1 Si1* C29* C1* C30 Figure S18. Calculated structures of (E)-2 in the ground state (C i symmetry) at the B97-D/6-31G(d,p) level: top view (top) and side view (bottom); blue, silicon; gray, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C29 = , C1 Si1 Si1* = , C29 Si1 Si1* = , C1 Si1 C29 = , Si1* Si1 C29 C30 = S24

25 C1 C29 Si1 Si2 C57 C73 C70 C86 C64 C80 Figure S19. Calculated structures of (Z)-2 in the ground state (C 1 symmetry) at the B97-D/6-31G(d,p) level: top view (top) and side view (bottom); blue, silicon; gray, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si2 = , Si1 C1 = , Si1 C57 = , Si2 C29 = , Si2 C73 = , C57 C73 = , C64 C80 = , a distance between the two pyrene ring centers = , C1 Si1 Si2 = , C57 Si1 Si2 = , C1 Si1 C57 = , C29 Si2 Si1 = , C73 Si2 Si1 = , C29 Si2 C73 = , Si2 Si1 C57 C70 = 51.14, Si1 Si2 C73 C86 = S25

26 HOMO ( 3.637) LUMO ( 2.148) LUMO+1 ( 1.908) Figure S20. Selected molecular orbitals of (Z)-2 (top view) at the B97-D/6-31G(d,p) level, together with the energy levels (ev). S26

27 Figure S21. Relative energies (kcal mol 1 ) of 1 at the B3LYP/6-31G(d,p) level. Figure S22. Relative energies (kcal mol 1 ) of 2 at the B3LYP/6-31G(d,p) level. Figure S23. Relative energies (kcal mol 1 ) of 2 at the CAM-B3LYP/6-31G(d,p) level. S27

28 Figure S24. Relative energies (kcal mol 1 ) of 2 at the B97-D/6-31G(d,p) level. S28

29 Figure S25. Calculated structures of (Z)-2 in the first excited singlet state (C 1 symmetry) at the TD-B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C57 = , Si2 C29 = , Si2 C73 = , C57 C73 = , C64 C80 = , a distance between the two pyrene ring centers = , C1 Si1 Si2 = , C57 Si1 Si2 = , C1 Si1 C57 = , C29 Si2 Si1 = , C73 Si2 Si1 = , C29 Si2 C73 = , Si2 Si1 C57 C70 = 49.88, Si1 Si2 C73 C86 = S29

30 Figure S26. Calculated structures of (Z)-2 in the first excited singlet state (C 1 symmetry) at the TD CAM-B3LYP/6-31G(d,p) level: top view (top) and side view (bottom); deep green, silicon; light green, carbon; white, hydrogen. Selected bond lengths (Å), bond angles ( ), and torsion angles ( ): Si1 Si1* = , Si1 C1 = , Si1 C57 = , Si2 C29 = , Si2 C73 = , C57 C73 = , C64 C80 = , a distance between the two pyrene ring centers = , C1 Si1 Si2 = , C57 Si1 Si2 = , C1 Si1 C57 = , C29 Si2 Si1 = , C73 Si2 Si1 = , C29 Si2 C73 = , Si2 Si1 C57 C70 = 45.94, Si1 Si2 C73 C86 = S30

31 Table S2. Structural data for (Z)-2 Si1 Si2 (Å) Si1 C57 (Å) Si2 Si1 C57 C70 ( ) C57 C73 (Å) C64 C80 (Å) Distance Between the Si2 C73 (Å) Si1 Si2 C73 C86 ( ) Two Pyrene Centers (Å) Experimental (X-ray) (6) (14) 52.66(13) 3.636(2) 4.036(3) (15) 48.73(14) Theoretical (B3LYP/6-31G(d,p)) Ground State st Excited State Theoretical (CAM-B3LYP/6-31G(d,p)) Ground State st Excited State Theoretical (B97-D/6-31G(d,p)) Ground State S31

32 Figure S27. Wiberg bond index (left) and NPA charge distribution (right) of (Z)-2 in the ground state at the B3LYP/6-31G(d,p) level. Figure S28. Wiberg bond index (left) and NPA charge distribution (right) of (Z)-2 in the first excited singlet state at the TD-B3LYP/6-31G(d,p) level. S32

33 Figure S29 Wiberg bond index (left) and NPA charge distribution (right) of (Z)-2 in the ground state at the CAM-B3LYP/6-31G(d,p) level. Figure S30. Wiberg bond index (left) and NPA charge distribution (right) of (Z)-2 in the first excited singlet state at the TD CAM-B3LYP/6-31G(d,p) level. S33

34 Table S3. Transition energy, wavelengths, and oscillator strength of the electronic transition of (Z)-2 at the ground state geometry using TD-B3LYP/6-31G(d,p) method. (HOMO = 332, LUMO = 333) S34

35 Figure S31. Calculated transitions (vertical blue bars) and simulated UV-vis absorption spectrum (black line) of (Z)-2 using TD-B3LYP/6-31G(d,p) method. S35

36 Table S4. Transition energy, wavelengths, and oscillator strength of the electronic transition of (Z)-2 at the ground state geometry using TD CAM-B3LYP/6-31G(d,p) method. (HOMO = 332, LUMO = 333) S36

37 Figure S32. Calculated transitions (vertical blue bars) and simulated UV-vis absorption spectrum (black line) of (Z)-2 using TD CAM-B3LYP/6-31G(d,p) method. S37

38 Table S5. Transition energy, wavelengths, and oscillator strength of the electronic transition of (Z)-2 at the first excited singlet state geometry using TD-B3LYP/6-31G(d,p) method. (HOMO = 332, LUMO = 333) S38

39 Figure S33. Calculated transitions (vertical blue bars) and simulated emission spectrum (black line) of (Z)-2 using TD-B3LYP/6-31G(d,p) method. S39

40 Table S6. Transition energy, wavelengths, and oscillator strength of the electronic transition of (Z)-2 at the first excited singlet state geometry using TD CAM-B3LYP/6-31G(d,p) method. (HOMO = 332, LUMO = 333) S40

41 Figure S34. Calculated transitions (vertical blue bars) and simulated emission spectrum (black line) of (Z)-2 using TD CAM-B3LYP/6-31G(d,p) method method. S41

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