Hetero Bodipy-dimers as heavy atom-free triplet photosensitizer showing long-lived triplet excited state for triplet-triplet annihilation upconversion

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1 Electronic Supplementary Information for: Hetero odipy-dimers as heavy atom-free triplet photosensitizer showing long-lived triplet excited state for triplet-triplet annihilation upconversion Wanhua Wu, Xiaoneng Cui and Jianzhang Zhao* State Key Laboratory of ine Chemicals, School of Chemical Engineering, Dalian University of Technology, E-208 Western Campus, 2 Ling Gong Road, Dalian , P. R. China. Phone/ax: zhaojzh@dlut.edu.cn Web: Index 1. General....S2 2. Synthesis and molecular structure characterization data s3 3. MR and HRMS spectra......s5 4. Details of photophysical properties S13 5. Upconversion details s15 6. Calculation details......s19 7. The coordinates of the triplet optimized geometries of complexes.....s22 S1

2 1. General Information All the chemicals used in synthesis are analytical pure and were used as received. Solvents were dried and distilled before used for synthesis. All samples in flash photolysis and upconversion experiments were deaerated with Ar for ca. 15 min before measurement and the gas flow is kept during the measurement. TTA Upconversion: Diode pumped solid state (DPSS) laser (532 nm) were used for the upconversions and the diameter of the laser spot is ca. 3 mm. In order to repress the scattered laser, a black box was put behind the fluorescent cuvette as beam dump to trap the laser after it passing through the cuvette. The upconversion quantum yields (Φ UC ) were determined with the prompt fluorescence of I-DP (the molecular structure is shown in Chart 1 in the main text) (Φ = 2.7 % in MeC) as the standards. The upconversion quantum yields were calculated with eq. 1, where Φ UC stands the upconversion quantum yields, A, I and η represents the absorbance, integrated photoluminescence intensity and the refractive index of the solvent, sam represents the sample, and std represents standard (Eq. 1). The equation is multiplied by factor 2 in order to make the maximum quantum yield to be unity. 1 Astd 1 10 I (1) sam η sam ΦUC = 2Φstd Asam 1 10 Istd ηstd The TTET efficiency was evaluated by the Stern-Volmer quenching constants, the concentration of the sensitizer was fixed at M, the lifetime of the sensitizer was measured by LP920 with increasing perylene concentration in the solution. 2 DT Calculations: The density functional theory (DT) calculations were used for optimization of the ground state geometries at 3LYP/6-31G level, The energy level of the T 1 state (energy gap between S 0 state and T 1 state) were calculated based on the optimized ground state geometries, The spin density surface of the organic sensitizer were optimized at the triplet state geometry. All the calculations were performed with Gaussian Singlet oxygen ( 1 O 2 ) quantum yields Φ Δ ): Φ Δ values of the triplet photosensitizers were calculated according to a modified literature method. 3 The light source of a spectrofluorometer was used for irradiation light source to get the constant monochromatic light. The irradiation wavelength for the samples and the reference was the same. Quantum yields for singlet oxygen generation in CH 2 Cl 2 were determined by monitoring the photooxidation of 1,3-diphenylisobenzofuran (DP) sensitized by the Ir complexes. The absorbance of DP was adjusted around 1.0 at 414 nm in air saturated CH 2 Cl 2, and absorbance of the photosensitizers were adjusted to at the irradiation wavelength. The photooxidation of DP was monitored at the interval of 10 s. The quantum yields of singlet oxygen generation (Φ Δ ) were calculated with Eq. 2, using Rose engal (Φ Δ = 0.80 in MeOH) as the reference, where superscripts sam and std designate Ru complexes and the standards, respectively, Φ Δ is the quantum yield of singlet oxygen, m is the slope of a plot of difference in change in absorbance of DP (at 420 nm) with the irradiation time and is the absorption correction factor, which is given by = 1 10 A (A is the absorbance at the irradiation wavelength). Reference: sam std sam std Δ = ΦΔ std sam [1] T.. Singh-Rachford,.. Castellano, Coord. Chem. Rev., 2010, 254, [2] M. J. risch, et al. Gaussian 09, Revision 01; Gaussian Inc., Wallingford, CT, [3]. Adarsh, R. R. Avirah, D. Ramaiah, Org. Lett. 2010, 12, Φ m m (2) S2

3 2. Synthesis and Molecular Structure Characterization Data O Cl + H i) ii) iii) CHO CHO iv) I CHO v) CHO iii) I CHO iii) I 3 5 vi) -3 I I-DP I Scheme S1. Synthesis of the odipy dimers as triplet photosensitizers -1, -2 and -3. The molecular structure of the reference compound I-DP was also shown. Reagents and conditions: i) dry CH 2 Cl 2, 3 -OEt 2, Et 3 ; ii) DM, POCl 3 ; iii) 2,4-Dimethyl-1H-pyrrole, DDQ, dry CH 2 Cl 2, 3 -OEt 2, Et 3 iv) IS, r.t.; v) phenylacetylene, Pd(PPh 3 ) 2 Cl 2, PPh 3, CuI, Et 3, reflux, 8 h, vi) 9-butyl-3-ethynylcarbazole, Pd(PPh 3 ) 2 Cl 2, PPh 3, CuI, Et 3, reflux, 8 h. Synthesis of compound 1: Under 2 atmosphere, acetyl chloride (0.7 ml, 0.78 g, 0.01 mol) and 2, 4-dimethylpyrrole (2.0 ml, 1.8 g, 0.02 mol) were added to anhydrous CH 2 Cl 2 (300 ml) via syringe, the mixture was stirred at room temperature over night. Then Et 3 (20 ml) and 3 Et 2 O (20 ml) were added under ice-cold condition, and reaction mixture was stirred for additional 1 h. After the reaction, the mixture was poured into water (200 ml), the organic layer was extracted with dichloromethane (DCM) and dried over anhydrous MgSO 4 and evaporated under reduced pressure. The crude product was further purified using column chromatography (silica gel, CH 2 Cl 2 : hexane = 1:1, v/v) to give compound 1 as red power. Yield: 1.2 g (45.8 %). 1 H MR (400 MHz, CDCl 3 ): 6.05 (s, 2H), 2.56 (s, 3H), 2.51 (s, 6H), 2.40 (s, 6H). Synthesis of compound 2: Under Ar atmosphere, DM (0.5 ml, 0.48 g, 6.6 mmol) was added dropwise to a round bottom flask (50 ml) containing POCl 3 (0.5 ml, 0.82 g, 5.4 mmol), while the temperature of the mixture was kept at 0 5 C. With the addition of DM, white solid appeared. The solution of compound 1 (360 mg, 1.37 mmol) dissolved in 1,2-dichloroethane (60 ml) was added to the above solution, the mixture were heated at 50 C and was stirred for 3 h. After the reaction, the mixture was poured into cold water, and the ph was brought to 7 8 using ahco 3 aqueous solution. The mixture was extracted with DCM, after evaporation of the solvent, the crude product was purified using column chromatography (silica gel, DCM was the eluent), red solid was obtained. Yield: mg (75.5%). 1 H MR (400 MHz, CDCl 3 ): (s, 1H), 6.24 (s, 1H), 2.78 (s, 3H), 2.73 (s, 3H), 2.68 (s, 1H), 2.58 (s, 3H), 2.47 (s, 3H). EI-HRMS: calcd ([C 15 H O] + ), m/z = , found, m/z = Synthesis of compound 3: To a solution of 2 (310 mg, 1.07 mmol) in anhydrous CH 2 Cl 2 (15 ml) was added excessive -iodosuccinimide (IS, mg, 2.14 mmol). The mixture was stirred at 40 C for 4 h (monitored by TLC until complete consumption of the starting material). The reaction mixture was then concentrated under vacuum, and the crude product was purified by column chromatography (silica gel, CH 2 Cl 2 ). The red band was collected and the S3

4 solvent was removed under reduced pressure to give the product as red solid. Yield: mg (92.1 %). 1 H MR (400 MHz, CDCl3): (s, 1H), 2.78 (s, 3H), 2.74 (s, 3H), 2.71 (s, 3H), 2.67 (s, 3H), 2.52 (s, 3H). EI-HRMS: calcd ([C 15 H OI] + ), m/z = , found, m/z = Synthesis of compound 4: Under Ar atmosphere, compound 3 (150.0 mg, 0.36 mmol), Pd(PPh 3 ) 2 Cl 2 (12.6 mg, mmol), PPh 3 (9.4 mg, mmol), CuI (7.2 mg, mmol) were dissolved in triethylamine (15 ml), the flask was vacuumed and back-filled with Ar for several times, and then phenylacetylene (74.0 mg, 0.72 mmol) was added via syringe. The solution was stirred at 60 C for 8 h. The solvent was removed under reduced pressure and the crude product was purified by column chromatography (silica gel, with CH 2 Cl 2 as the eluent), dark red solid was obtained. Yield: mg (75.1 %). 1 H MR (400 MHz, CDCl 3 ): (s, 1H), (m, 2H), (m, 3H), 2.80 (s, 3H), 2.76 (s, 3H), 2.74 (s, 3H), 2.72 (s, 3H), 2.61(s, 3H). Synthesis of compound 5: Under Ar atmosphere, compound 3 (430 mg, 1.03 mmol) and 2,4-dimethylpyrrole (196.4 mg, 2.06 mmol) were dissolved in dry CH 2 Cl 2 (200 ml). A few drops of trifluoroacetic acid (TA) was added to the solution and reaction mixture was stirred overnight at RT. After disappearance of the compound 3 (monitored via TLC), a solution of DDQ (230 mg, 1.03 mmol) in newly distilled TH was added and the stirring was continued for 2 h. Absolute triethylamine (3 ml) was then added to the mixture. After stirring for 15 min, 3 OEt 2 (3 ml) was added dropwise with ice bath cooling. After stirring for another 2 h, the reaction mixture was washed with water several times and extracted with DCM. The organic phase was dried over a 2 SO 4. The solvent was evaporated and the residue was purified by column chromatography (silica gel, DCM) to obtain red solid. Yield: mg (34.4 %). 1 H MR (400 MHz, CDCl 3 ): δ 6.02 (s, 2H), 2.70 (s, 3H), 2.65 (s, 3H), 2.56 (s, 6H), 2.50 (s, 3H), 2.39 (s, 3H), 2.30 (s, 3H), 1.68 (s, 6H). 13 C MR (100 MHz, CDCl 3 ) δ 156.2, 151.2, 143.6, 142.6, 142.3, 138.2, 133.2, 133.0, 132.0, 126.7, 121.6, 86.3, 20.0, 17.7, 16.2, 15.4, 14.9, 14.2, EI-HRMS: calcd ([C 27 H I] + ), m/z = , found, m/z = Synthesis of compound -1: -1 was prepared by a similar procedure to compound 5, compound 2 (40.0 mg, 0.14 mmol) was used as starting material, instead of compound was obtained as red solid. Yield: 25.5 mg (34.9 %). 1 H MR (400 MHz, CDCl 3 ): δ = 6.16 (s, 1H), 6.01 (s, 2H), 2.67 (s, 3H), 2.56 (s, 9H), 2.46 (s, 3H), 2.38 (s, 3H), 2.27 (s, 3H), 1.69 (s, 6H), 13 C MR (100 MHz, CDCl 3 ) δ = 157.0, 155.9, 148.9, 143.6, 142.8, 142.3, 136.1, 134.0, 133.3, 132.2, 131.8, 125.5, 122.8, 121.4, 17.8, 16.9, 15.1, 14.8, 14.1, MALDI-HRMS: calcd ([C 27 H ] + ), m/z = , found, m/z = Synthesis of compound -2: -2 was prepared by a similar procedure to compound 5, compound 4 (84.0 mg, 0.22 mmol) was used as starting material, instead of compound was obtained as red solid. Yield: 32.0 mg (23.9 %). 1 H MR (400 MHz, CDCl 3 ): (m, 2H), (m, 3H), 6.03 (s, 2H), 2.72 (s, 3H), 2.71 (s, 3H), 2.61 (s, 3H), 2.57 (s, 6H), 2.41(s, 3H), 2.31 (s, 3H), 1.70 (s, 6H), 13 C MR (100 MHz, CDCl 3 ) δ = 158.0, 156.2, 151.0, 142.9, 142.7, 137.7, 133.4, 132.6, 132.3, 132.1, 131.5, 128.6, 128.5, 126.4, 123.5, 121.6, 116.8, 96.8, 81.7, 17.3, 16.5, 15.3, 14.9, 14.2, 13.9, MALDI-HRMS: calcd ([C 35 H ] + ), m/z = , found, m/z = Synthesis of compound -3: Under Ar atmosphere, compound 5 (60.0 mg, mmol) and 9-butyl-3-ethynylcarbazole (49.5 mg, 0.2 mmol) were dissolved in mixed solvent TH/Triethylamine (10 ml/ 5 ml), the flask was vacuumed and back-filled with Ar for several times, then Pd(PPh 3 ) 2 Cl 2 (7.0 mg, 0.01 mmol), PPh 3 (5.2 mg, 0.02 mmol), CuI (4.0 mg, 0.02 mmol) was added. The mixture was stirred at 60 C for 8 h. The solvent was removed under reduced pressure and the crude product was purified by column chromatography (silica gel, ethyl acetate : hexane = 1 : 4, v/v). Purple solid was obtained. Yield: 38.9 mg (53.8 %). 1 H MR (400 MHz, CDCl 3 ): δ = 8.28 (s, 1H), 8.12 (d, 1H, J = 7.5 Hz), 7.64 (d, 1H, J = 8.4 Hz), 7.50 (t, 1H, J = 7.5 Hz), (m, 2H), (m, 2H), 6.03 (s, 2H), 4.32 (t, 2H, J = 7.1 Hz), 2.76 (s, 3H), 2.72 (s, 3H), 2.64 (s, 3H), 2.57 (s, 6H), 2.41 (s, 3H), 2.31 (s, 3H), (m, 2H), 1.71 (s, 6H), (m, 2H), 0.96 (t, 3H, J = 7.5 Hz). 13 C MR (101 MHz, CDCl 3 ) δ = 158.4, 156.0, 150.2, 142.7, 142.5, 140.9, 140.2, 137.0, 133.5, 132.4, 132.1, 129.2, 126.3, 126.1, 123.9, 123.0, 122.5, 121.5, 120.7, 119.5, 117.6, 117.6, 113.2, 113.2, 109.1, 108.9, 98.3, 79.5, 43.1, 29.8, 20.7, 17.2, 16.5, 15.2, 14.8, 14.2, 14.0, 13.9, MALDI-HRMS: calcd ([C 45 H ] + ), m/z = , found, m/z = S4

5 3. MR and HRMS spectra ig. S1 1 H MR of 1 (400 MHz, CDCl 3 ) ppm CHO ig. S2 1 H MR of 2 (400 MHz, CDCl 3 ). ppm S5

6 zjz (4.767) Cm (286:293-2:24) TO MS EI+ 4.23e4 % m/z CHO ig. S3 EI-HRMS of compound I CHO ig. S4 1 H MR of 3 (400 MHz, CDCl 3 ) ppm S6

7 zjz (4.267) Cm (256:263-50:66) 100 % TO MS EI+ 5.11e m/z I CHO ig. S5 EI-HRMS of compound CHO ppm ig. S6 1 H MR of 4 (400 MHz, CDCl 3 ). S7

8 I ig. S7 1 H MR of 5 (400 MHz, CDCl 3 ) ppm I ig. S8 13 C MR of 5 (100 MHz, CDCl 3 ) ppm S8

9 zjz (6.067) Cm (364-75:88) TO MS EI+ 437 % m/z I ig. S9 EI-HRMS of compound ig. S10 1 H MR of -1 (400 MHz, CDCl 3 ) ppm S9

10 ig. S11 13 C MR of -1 (100 MHz, CDCl 3 ) ppm ( ) (0.066) Cn (Cen,4, 50.00, Ht); Sm (SG, 2x3.00); Sb (15,10.00 ); Cm (1:17) e % m/z ig. S12 MALDI-HRMS of -1. S10

11 ig. S13 1 H MR of -2 (400 MHz, CDCl 3 ). ppm ig. S14 13 C MR of -2 (100 MHz, CDCl 3 ). ppm S11

12 ( ) (0.965) Cn (Cen,4, 50.00, Ht); Sm (SG, 2x3.00); Sb (15,10.00 ); Cm (29:30) e3 % m/z ig. S15 MALDI-HRMS of ig. S16 1 H MR of -3 (400 MHz, CDCl 3 ) ppm S12

13 ig. S17 13 C MR of -3 (100 MHz, CDCl 3 ) ppm ( ) (2.198) Cn (Cen,4, 50.00, Ht); Sm (SG, 2x3.00); Sb (15,10.00 ); Cm (55:66) e % m/z ig. S18 MALDI-HRMS of -3. S13

14 4. Details of photophysical properties Intensity / a.u Excitation Absorption a -1 Intensity / a.u. Excitation b 1.2 Absorption Intensity / a.u. 1.6 c Excitation Absorption Wavelength / nm Wavelength / nm Wavelength / nm ig. S19 Comparison of the normalized UV-vis absorption and the excitation spectra of the photosensitizers. The excitation spectra of (a) -1, (b) -2 and (c) -3 were recorded with λ em = 550 nm, λ em = 600 nm and λ em = 650 nm respectively. c = mol dm -3 in DCM. 20 C Δ O.D a μs μs μs 0 μs Wavelength / nm Δ O.D b τ T = μs Time / μs ig. S20 (a): anosecond time-resolved transient absorption difference spectra of -1. After pulsed excitation (λ ex = 532 nm). (b) Decay traces of -1 at 510 nm. c = M in deaerated CH 2 Cl C. S14

15 Δ O.D τ = n -0.2 a Time / ns Δ O.D τ = ns b Time / ns ig. S21 Decay traces of (a) -1 and (b) -2 monitored at 510 nm. c = M in air saturated DCM. 20 C. 5. Upconversion details Intensity / a.u perylene Wavelength / nm ig. S22 Upconversion with -3 as triplet photosensitizers ( M) and perylene as acceptor ( M) in DCM. λ ex = 532 nm, laser power is 8.8 mw (124.6 mw cm -2 ), 20 C. S15

16 Counts τ D = μs Counts τ D = μs Time / μs Time / μs τ D = μs 1000 Prompt fluorescence τ P = 4.0 ns Counts 100 Counts Time / μs Time / ns ig. S23 Delayed fluorescence observed in the TTA upconversion with compound -1, -2 and -3 as triplet photosensitizers and perylene as the triplet acceptor. Excited at 532 nm (nanosecond pulsed OPO laser synchronized with spectrofluorometer) and monitored at 470 nm. Under this circumstance the compounds -1, -2 and -3 are selectively excited and the emission is due to the upconverted emission of perylene. In deaerated DCM. c[photosensitizers] = M; c [perylene] = M; 20 C. S16

17 Electronic Supplementary Material (ESI) for Chemical Communications a b c d e f ig. S24 Time-resolved emission spectra (TRES) of the sensitizers -1 (a), -2 (c), -3 (e) and the upconverted fluorescence of perylene using -1 (b) -2 (d) -3 (f) as the sensitizers. TRES of the prompt fluorescence of the triplet photosensitizers were recorded with excitation with EPL picosecond pulsed laser. The TRES of the delayed fluorescence (the TTA upconversion) of perylene were recorded with excitation with the nanosecond pulsed OPO laser. c [Photosensitizers] = M. c [perylene] = M. In deaerated CH2Cl2. 20 C. S17

18 orm. intensity / a.u Wavelength / nm ig. S25 Prompt fluorescence of perylene. Recorded with steady-state spectrofluorometer. λ ex = 400 nm. In CH 2 Cl 2 ( M). 20 C. τ 0 / τ I-DP x x x10-5 C [perylene] / mol L -1 ig. S26 Stern-Volmer plots generated from triplet excited state lifetime (τ T ) quenching of -1, -2 and I-DP measured as a function of perylene concentration in DCM. The lifetimes were measured with the nanosecond time-resolved transient absorption. The concentration of the sensitizers were fixed at M. 20 C. S18

19 6. Calculation details LUMO LUMO+1 HOMO HOMO 1 ig. S27 rontier molecular orbitals of -1. Calculated by DT at the 3LYP/6-31G((d) using Gaussian 09W. 2 Table S1. Electronic Excitation Energies (ev) and corresponding Oscillator Strengths (f), main configurations and CI coefficients of the Low-lying Electronically Excited States of complex -1, Calculated by TDDT//3LYP/6-31G(d), based on the DT//3LYP/6-31G(d) Optimized Ground State Geometries. Triplet Electronic TDDT//3LYP/6-31G(d) transition Energy /ev) [a] f [b] Composition [c] CI [d] S0 T ev / 834 nm [e] HOMO LUMO HOMO LUMO S0 T ev / 776 nm [e] HOMO 1 LUMO HOMO 1 LUMO [a] Only the selected low-lying excited states are presented. [b] Oscillator strength. [c] Only the main configurations are presented. [d] The CI coefficients are in absolute values. [e] o spin-orbital coupling effect was considered, thus the f values are zero. S19

20 LUMO LUMO+1 HOMO 3 HOMO HOMO 1 HOMO 2 ig. S28 rontier molecular orbitals of -2. Calculated by DT at the 3LYP/6-31G(d) using Gaussian 09W. Table S2. Electronic Excitation Energies (ev) and corresponding Oscillator Strengths (f), main configurations and CI coefficients of the Low-lying Electronically Excited States of complex -2, Calculated by TDDT//3LYP/6-31G(d), based on the DT//3LYP/6-31G(d) Optimized Ground State Geometries. Triplet Electronic transition TDDT//3LYP/6-31G(d) Energy / ev [a] f [b] Composition [c] CI [d] S0 T ev / 836 nm e HOMO 1 LUMO HOMO LUMO HOMO LUMO S0 T ev/ 808 nm e HOMO 2 LUMO HOMO 1 LUMO HOMO LUMO [a] Only the selected low-lying excited states are presented. [b] Oscillator strength. [c] Only the main configurations are presented. [d] The CI coefficients are in absolute values. [e] o spin-orbital coupling effect was considered, thus the f values are zero. S20

21 Electronic Supplementary Material (ESI) for Chemical Communications ig. S29 Isosurfaces of spin density of -3 at the optimized triplet state geometries. Calculation was performed at 3LYP/6-31G(d) level with Gaussian 09W. LUMO HOMO LUMO+1 HOMO 1 HOMO 2 ig. S30 rontier molecular orbitals of -3. Calculated by DT at the 3LYP/6-31G(d) using Gaussian 09W. S21

22 Table S3. Electronic Excitation Energies (ev) and corresponding Oscillator Strengths (f), main configurations and CI coefficients of the Low-lying Electronically Excited States of complex -3, Calculated by TDDT//3LYP/6-31G(d), based on the DT//3LYP/6-31G(d) Optimized Ground State Geometries. Triplet Electronic TDDT//3LYP/6-31G(d) transition Energy / ev [a] f [b] Composition [c] CI [d] S0 T ev / 840 nm e HOMO 2 LUMO HOMO LUMO S0 T ev/ 835 nm e HOMO 1 LUMO [a] Only the selected low-lying excited states are presented. [b] Oscillator strength. [c] Only the main configurations are presented. [d] The CI coefficients are in absolute values. [e] o spin-orbital coupling effect was considered, thus the f values are zero. 7. The coordinates of the optimized ground state geometries of compounds Compound -1 (DT//3LYP/6-31G(d)) Charge = 0 Multiplicity = 1 C C C C C C C C H H H C H H H C H H H S22

23 C H H H C C H H H C C C C C C C C H C H H H C H H H C H H H C H H H H C C H Compound -2 (DT//3LYP/6-31G(d)) Charge = 0 Multiplicity = 1 C C C C C C C S23

24 C C H H H C H H H C H H H C H H H C C H H H C C C C C C C C H C H H H C H H H C H H H C H H S24

25 H H C C C C C C C H C H C H H H Compound -3 (DT//3LYP/6-31G(d)) Charge = 0 Multiplicity = C C C C H C H C H C C C C C H C H H H C C C H H H C C C C S25

26 C C C C H H H C H H H C H H H C H H H C C H H H C C C C C C C C H C H H H C H H H C H H H C S26

27 H H H H C C S27