Electronic Supplementary Material (ESI) for ChemComm. This journal is The Royal Society of Chemistry 2014 Electronic Supplementary Information Unique ultrafast energy transfer in a series of phenylenebridged subporphyrin-porphyrin hybrids Juwon Oh, a Jooyoung Sung, a Masaaki Kitano, b Yasuhide Inokuma, b Atsuhiro Osuka, b,* and Dongho Kim a,* a Department of Chemistry, Yonsei University, Seoul 120-749, Korea, b Department of Chemistry, Graduate School of Science Kyoto University, Kyoto 060-8502, Japan. E-mail: dongho@yonsei.ac.kr, osuka@kuchem.kyoto-u.ac.jp Contents 1. Experimental Details 2. Supporting Information Table S1. List of parameters measured in steady-state and time-resolved spectroscopies in toluene Table S2. List of parameters for Förster-type incoherent energy transfer rate calculation Table S3. Calculated vertical excitation energies of 3 Table S4. Calculated vertical excitation energies of 6 Figure S1. The absorption spectra of 3 and the excitation spectra of 3-6 in toluene Figure S2. The fluorescence spectra of 3-6 in toluene by photoexcitation at 370 and 420 nm Figure S3. The fluorescence decay profiles of 3-6 in toluene by photoexcitation at 380 nm Figure S4. Energy levels and structures of the frontier MOs of 3 1
Figure S5. Energy levels and structures of the frontier MOs of 6 Figure S6. Representative electron density difference maps between electronic ground and excited state of 3 Figure S7. Representative electron density difference maps between electronic ground and excited state of 6 2
1. Experimental Details Steady-state Absorption and Emission Measurements. Steady-state absorption spectra were obtained with an UV-VIS-NIR spectrometer (Varian, Cary5000) and steady-state fluorescence spectra were measured on a Hitachi model F-2500 fluorescence spectrophotometer and a Scinco model FS-2. For the observation of steady-state emission spectra in near-infrared (NIR) region, a photomultiplier tube (Hamamatsu, R5108), a lock-in amplifier (EG&G, 5210) combined with a chopper and a CW He-Cd laser (Melles Griot, Omnichrome 74) for the 442 nm excitation were used. Pico-second Time-resolved Fluorescence Measurements. Time-resolved fluorescence lifetime experiments were performed by the time-correlated single-photon-counting (TCSPC) technique. As an excitation light source, we used a Ti:sapphire laser (Mai Tai BB, Spectra- Physics) which provides a repetition rate of 800 khz with ~ 100 fs pulses generated by a homemade pulse-picker. The output pulse of the laser was frequency-doubled by a 1 mm thickness of a second harmonic crystal ( -barium borate, BBO, CASIX). The fluorescence was collected by a microchannel plate photomultiplier (MCP-PMT, Hamamatsu, R3809U-51) with a thermoelectric cooler (Hamamatsu, C4878) connected to a TCSPC board (Becker&Hickel SPC-130). The overall instrumental response function was about 25 ps (the full width at half maximum (fwhm)). A vertically polarized pump pulse by a Glan-laser polarizer was irradiated to samples, and a sheet polarizer, set at an angle complementary to the magic angle (54.7 ), was placed in the fluorescence collection path to obtain polarization-independent fluorescence decays. Femto-second Time-resolved Fluorescence Measurements. A femto-second fluorescence upconversion apparatus was used for the time-resolved spontaneous fluorescence. The beam sources were a mode-locked Ti:sapphire laser also used in TCSPC system. The second harmonic of the fundamental generated by a 200-μm thick BBO crystal served as pump pulse. Residual fundamental pulse was used as a gate pulse. The visible pump pulse passes a sequence of UV fused silica prisms (69 ) for pulse compression and the optimum separation between the apexes of each prism was found to be 47.5 cm. The residual fundamental pulse was also compressed by a SF10 prism (60 ) compressor with optimal separation of 28.5 cm between the apexes of each prism. The pump beam was focused onto a 500-μm thick quartz cuvette containing sample solution using a 5-cm focal length plano-convex lens with a magic angle (54.7 ) in order to prevent polarization-dependent signals. The cuvette was mounted on a motor-driven stage and moved constantly back and forth to minimize photo-degradation. Collection of the fluorescence and focusing into a 1 mm-thick BBO crystal for frequency conversion was achieved by a reflecting microscope objective lens (Newport). The FWHM of the cross-correlation function between the scattered pump pulse (i.e. 385 nm) and the gate 3
pulse (i.e. 770 nm) is measured to be ~180 fs. The average excitation power was kept at a level below 1 mw in order to minimize thermal lens effect. In this excitation intensity regime the fluorescence dynamics was be independent of the excitation intensity for all samples. Computational Methods. Quantum mechanical calculation were performed with the Gaussian 09 program suite. All calculations were carried out by the density functional theory (DFT) method with Becke s three-parameter hybrid exchange functionals and the Lee-Yang- Parr correlation functional (B3LYP), employing the 6-31G(d,p) basis set. The oscillator strength was calculated by performing time-dependent (TD) DFT calculation. The X-ray crystallographic structures were used for 3 as initial geometries for geometry optimization. To simulate the ground-state absorption spectra, we used TDDFT calculations with the same functional and basis set as used in the geometry optimization. Electron density difference maps (EDDM) were calculated by GAUSSSUM 2.2 program package using results of TDDFT. 4
2. Supporting Information Table S1 : List of parameters measured in steady-state and time-resolved spectroscopies in toluene. Sample 3 4 5 6 λ abs (nm) 372, 416, 461, 489, 541 372, 416, 462, 494, 541 373, 416, 466, 497, 541 372, 416, 460, 488, 541 Relative absorbance a (at 372 nm) λ fl (nm) Relative intensity b Ф F τ F (fs) c τ F (ns) d 1.00 594, 641 2.0 0.035 360 ± 20 2.2 0.46 593, 641 1.9 0.036 190 ± 15 2.2 0.31 595, 641 1.8 0.038 150 ± 15 2.2 1.10 591, 640 3.9 0.028 680 ± 20 2.2 a The relative absorbance of 3-6 are obtained by dividing the absorbance of 3-6 with that of 3 at 372 nm when the absorption spectra of 3-6 are normalized at 416 nm. b The relatvie intensities of 3-6 are estimated by dividing the intensity of v(0,1) bands (640-641 nm) with that of v(0,0) bands (591-595 nm). c All decay components are obtained from the time-resolved fluorescence profiles of 3-6 recorded by photoexcitation at 385 nm and probe at 520 nm. The time components are measured by the femtosecond upconversion technique. d The nanosecond time constants were obtained by the picosecond time-resolved fluorescence profiles based on the time-correlated single photon counting (TCSPC) technique. 5
Table S2 : List of parameters for Förster-type incoherent energy transfer rate calculation. Sample k F J ( x10 14 M -1 cm -1 nm 4 ) a Φ D b κ c R (Å) τ D d n e 3 (1.4 ps) -1 6.67 0.14 3.92 12.1 2.95 ns 1.496 6 (1.0 ps) -1 6.67 0.14 2.77 10.8 2.95 ns 1.496 a Spectral overlap was measured based on the absorption spectra of 2 and the fluorescence spectra of 2 with following equation, J = F(λ)ε(λ)λ 4 dλ. b, d Ref 1. c Dipole-dipole orientation factor was estimated with the crystal structure of 3 and optimised structure of 6. e Refractive index of toluene at 20. 6
Table S3 : Calculated vertical excitation energies of 3 at B3LYP/6-31G(d,P) level. No. Energy [cm -1 ] λ [nm] Oscillator strength MO contribution a T 1 18828 531 0.026 H-1->L+1 (38%), HOMO->LUMO (51%) T 2 18869 530 0.0093 H-1->LUMO (38%), HOMO->L+1 (50%) T 3 21234 471 0.3542 H-3->L+3 (12%), H-2->LUMO (30%), HOMO->LUMO (16%), HOMO->L+2 (24%) T 4 21781 459 0.0636 H-3->L+2 (21%), H-2->L+3 (24%), HOMO->L+3 (40%) T 5 22057 453 0.006 H-2->L+1 (68%), HOMO->L+1 (20%) T 6 22106 452 0.0047 H-2->LUMO (39%), HOMO->L+2 (41%) T 7 22847 434 0.0156 H-3->L+3 (12%), H-2->L+2 (55%), HOMO->L+2 (17%) T 8 23427 427 0.0021 H-2->L+3 (38%), HOMO->L+3 (49%) T 9 23511 425 0.0115 H-1->LUMO (10%), H-1->L+2 (78%) T 10 24269 412 0.0007 H-1->L+3 (89%), H-2->L+3 (8%) a Minor configurations of which contributions are less than 8 % are omitted in list. 7
Table S4 : Calculated vertical excitation energies of 6 at B3LYP/6-31G(d,P) level. No. Energy [cm -1 ] λ [nm] Oscillator strength MO contribution a T 1 18900 529 0.0025 H-2->LUMO (36%), H-1->L+1 (14%), HOMO->L+1 (40%) T 2 18915 528 0.0093 H-2->L+1 (35%), H-1->LUMO (14%), HOMO->LUMO (41%) T 3 21296 470 0.0913 H-1->LUMO (47%), HOMO->LUMO (15%), H-1->L+1 (8%), HOMO->L+1 (8%) T 4 21323 469 0.0062 H-1->LUMO (10%), H-1->L+1 (52%), HOMO->L+1 (17%) H-2->L+1 (8%), HOMO->LUMO (8%) T 5 21789 459 0.0736 H-3->L+3 (24%), H-1->L+2 (34%), HOMO->L+2 (30%) T 6 21997 455 0.0716 H-3->L+2 (21%), H-1->L+3 (27%), HOMO->L+3 (30%) T 7 22872 437 0.0035 H-1->L+3 (40%), HOMO->L+3 (54%) T 8 23188 431 0.0016 H-1->L+2 (37%), HOMO->L+2 (60%) T 9 23815 420 0.0271 H-2->L+3 (86%) T 10 24114 415 0.0016 H-3->LUMO (23%), H-3->L+1 (15%), H-2->L+2 (55%) a Minor configurations of which contributions are less than 8 % are omitted in list. 8
Figure S1. The excitation spectra of 3-6 and the molar absorptivity spectra of 3 in toluene. The excitation spectra are recorded for the fluorescence intensity at (a) 520 and (b) 640 nm. 9
Figure S2. The fluorescence spectra of 3-6 in toluene by photoexcitation at (a) 370 and (b) 405 nm. The spectra of 3-6 in the range of 415-450 nm by photoexcitation 405 nm are magnified for clarifying the S 2 emission of subunit 2 (inset of (b)). The asterisks at (a) 415 and (b) 455 nm indicate solvent raman signals. 10
Figure S3. The fluorescence decay profiles of 3-6 in toluene by photoexcitation at 380 nm. The fluorescence decay profiles monitered at (a) 520 nm and (b) 640 nm. (The longer decay componenet, 2.2 ns, obtained at (a) arises from the Q(2,0) state of ZnP subunit.) 11
Figure S4. Energy levels and structures of the frontier MOs of 3. The quantum mechanical calculation carried out based on the crystal structure of 3. 2 12
Figure S5. Energy levels and structures of the frontier MOs of 6. The quantum mechanical calculation carried out based on optimized structure of 6 with B3LYP/6-31G(d,P) level. 13
Figure S6. Representative electron density difference maps between the electronic ground and excited state of 3. Red and blue colors indicate electron rich and deficient characters in the excited electronic states. 14
Figure S7. Representative electron density difference maps between the electronic ground and excited state of 6. Red and blue colors indicate electron rich and deficient characters in the excited electronic states. References [1] Y. Inokuma, Z. Yoon, D. Kim, A. Osuka, J. Am. Chem. Soc., 2007, 129, 4747. [2] Y. Inokuma, S. Hayashi, A. Osuka, Chem. Lett., 2009, 38, 206. 15