side-chain engineering in a thermal precursor approach for ......supplementary information for...

Supplementary Information for

Side-chain engineering in a thermal precursor approach

for efficient photocurrent generation

Kohtaro Takahashi,a Daichi Kumagai,b Naoya Yamada,b Daiki Kuzuhara,a Yuji Yamaguchi,b

Naoki Aratani,a Tomoyuki Koganezawa,c Sota Koshika,d Noriyuki Yoshimoto,d Sadahiro Masuo,e

Mitsuharu Suzuki,*a Ken-ichi Nakayama,*bf and Hiroko Yamada*a

aGraduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan

bDepartment of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan

cJapan Synchrotron Radiation Research Institute (JASRI), SPring-8, Sayo, Hyogo 679-5198, Japan

dGraduate School of Engineering, Iwate University, Morioka, Iwate 020-8551, Japan

eDepartment of Applied Chemistry for Environment, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan

fDepartment of Material and Life Science, Osaka University, Suita, Osaka 565-0871, Japan

Correspondence and requests for materials should be addressed to

M.S. ([email protected]), K.N. ([email protected]), or H.Y. ([email protected])

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2017

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Contents

1. Supplementary Figures and Tables··················································································· S2

2. Experimental ·········································································································· S17

3. Absorption Spectra in Solutions ···················································································· S30

4. NMR Spectra ·········································································································· S31

5. References ············································································································· S47

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1. Supplementary Figures and Tables

Figure S1. Structure of C1-DPP–BP optimized at the B3LYP/6-31G(d) level of theory: (a) Top view; (b) Side

view with the dihedral angles between the BP and DPP planes; (c) Distribution of the HOMO coefficient; (d)

Distribution of the LUMO coefficient. Torsion angles defined with S1–C55–C5–C6 and S3–C83–C15–C16

are 30°.

Figure S2. Crystal structure of C6-DPP–CP: (a) Top view; (b) Side view. Solvents and hydrogen atoms are

omitted for clarity. Thermal ellipsoids represent 50% probability. Torsion angles defined with S1–C55–C5–C6

and S3–C83–C15–C16 are 10° and 17°, respectively.

(a)

(c)

(b)

(d)

30°

30°

S3

C16

C15

C83S1

C6

C5

C55

S3

O3

O4

N3 N2

N5

N6S4

O1

O2

N4 N1

S1

S2

(a)

(b)

10°17°

N7

N8

C6

C5

C55

C16

C15

C83

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Table S1. Single-crystal diffraction parameters and crystal data of C6-DPP–CP.

Empirical formula C117H132Cl9N8O4S4

Formula weight 2161.59

Temperature 90 K

Wavelength 0.71073 Å

Crystal system Triclinic

Space group P-1

Unit cell dimensions a = 17.452(10) Å = 106.590(8)°

b = 17.834(10) Å = 100.966(9)°

c = 20.187(11) Å = 109.185(7)°

Volume 5400(5) Å3

Z 2

Density (calculated) 1.330 Mg m–3

Absorption coefficient 0.368 mm–1

F(000) 2278

Crystal size 0.300 × 0.100 × 0.050 mm3

Theta range for data collection 1.301 to 23.500°

Index ranges –19 ≤ h ≤ 19, –20 ≤ k ≤ 18, –18 ≤ l ≤ 22

Reflections collected 23951

Independent reflections 15747 [R(int) = 0.0693]

Completeness to theta = 27.48° 98.6 %

Max. and min. transmission 0.982 and 0.641

Refinement method Full-matrix least-squares on F2

Data / restraints / parameters 15747 / 6 / 1290

Goodness-of-fit on F2 1.047

Final R indices [I > 2σ(I)] R1 = 0.1093, wR2 = 0.2730

R indices (all data) R1 = 0.1978, wR2 = 0.3568

Largest diff. peak and hole 0.893 and–0.872 e.Å–3

CCDC No. 1491998

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Figure S3. TGA curves of Cn-DPP–CPs. The weight loss starts at 131–136 ºC and ends at 181–191 ºC. The

observed weight loss proportions for C2-, C4-, C6-, C8- and C10-DPP–CP are 15.2, 14.0, 13.1, 12.3, and

11.6%, respectively, which are in good agreement with the calculated values for the elimination of four

isobutene units per molecule (15.0, 14.0, 13.1, 12.3 and 11.6%). The decomposition temperatures of C2-, C4-,

C6-, C8-, and C10-DPP–CPs are 432, 403, 378, 359, and 354 ºC, respectively.

Figure S4. Photoelectron spectra in air of the thin films of (a) C2-DPP–BP, (b) C4-DPP–BP, (c) C6-DPP–BP,

(d) C8-DPP–BP, and (e) C10-DPP–BP on ITO-coated glass substrates.

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Table S2. Performance of BHJ OPVs based on C4-DPP–BP:PC61BM with different p:n ratios (rough

screening).a

p:n Ratio (wt.)b JSC (mA cm–2) VOC (V) FF PCE (%)

2:1 13.0 0.64 0.47 3.9

1:1 14.2 0.66 0.47 4.4

1:2 4.2 0.61 0.40 1.0 aConditions for active-layer deposition: 10 mg mL–1 in CHCl3, 800 rpm, 40 s, annealed at 200 °C for 10 min. bCalculated as the ratio between C4-DPP–CP and PC61BM.

The optimum p:n ratio was determined as 1:1 for C4-DPP–BP:PC61BM among the examined conditions.

Table S3. Performance of BHJ OPVs based on C4-DPP–BP:PC61BM deposited at different solution

concentrations (rough screening).a

Concentration (mg mL–1)b JSC (mA cm–2) VOC (V) FF PCE (%)

8 14.8 0.65 0.46 4.4

10 14.2 0.66 0.47 4.4

12 14.0 0.63 0.39 3.5

15 11.8 0.65 0.38 2.9 aConditions for active-layer deposition: C4-DPP–CP:PC61BM = 1:1 (wt.) in CHCl3, 800 rpm, 40 s,

annealed at 200 °C for 10 min. bConcentration of cast solutions.

The optimum solution concentration was determined as 8 mg mL–1 for C4-DPP–BP:PC61BM among the

examined conditions.

Table S4. Performance of BHJ OPVs based on C4-DPP–BP:PC61BM with different p:n ratios (fine screening).


4:3 14.9 0.65 0.46 4.5

1:1 14.8 0.65 0.46 4.4



Table S5. Performance of BHJ OPVs based on C4-DPP–BP:PC61BM deposited using different amounts of

CS2 as solvent additive.a

CS2 content (vol%)b JSC (mA cm–2) VOC (V) FF PCE (%)

0 14.0 0.67 0.51 4.8

5 13.4 0.67 0.51 4.6

10 14.5 0.67 0.51 5.0

20 15.4 0.67 0.48 4.9 aConditions for active-layer deposition: 8 mg mL–1, 800 rpm, 40 s, annealed at 200 °C for 10 min. bAmounts of CS2 against CHCl3 in deposition solutions.

The optimum amount of CS2 in CHCl3 was determined as 10% v/v for C4-DPP–BP:PC61BM among the

examined conditions.

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concentrations (fine screening).a


8 14.5 0.67 0.51 5.0

8.5 15.2 0.67 0.52 5.2

9 15.6 0.66 0.49 5.1 aConditions for active-layer deposition: C4-DPP–CP:PC61BM = 4:3 (wt.) in CHCl3 containing 10 vol% of

CS2, 800 rpm, 40 s, annealed at 200 °C for 10 min. bConcentrations of cast solutions.

The optimum solution concentration was determined as 8.5 mg mL–1 for C4-DPP–BP:PC61BM among the

examined conditions. The thickness of the active layer deposited at this concentration was 105 nm.

Table S7. Performance of BHJ OPVs based on C6-DPP–BP:PC61BM with different p:n ratios.a


4:1 10.81 0.68 0.39 2.84

3:1 11.85 0.69 0.43 3.49

2:1 12.87 0.69 0.43 3.86

1:1 8.50 0.73 0.40 2.45



Table S8. Performance of BHJ OPVs based on C6-DPP–BP:PC61BM converted at different temperatures.a

Temperature (°C)b JSC (mA cm–2) VOC (V) FF PCE (%)

160 9.8 0.66 0.34 2.2

180 12.9 0.69 0.43 3.9

200 13.6 0.69 0.49 4.5

220 13.0 0.68 0.48 4.3 aConditions for active-layer deposition: C6-DPP–CP:PC61BM = 2:1 (wt.) 10 mg mL–1 in CHCl3, 800 rpm,

40 s, bHeating periods: 30 min for 160 and 180 °C, 10 min for 200 and 220 °C.

The optimum annealing temperature was determined as 200 °C for C6-DPP–BP:PC61BM among examined

conditions.


concentrations.a


8 10.1 0.68 0.46 2.9

10 13.6 0.69 0.49 4.5

12 8.5 0.67 0.35 2.0 aConditions for active-layer deposition: C6-DPP–CP:PC61BM = 2:1 (wt.) in CHCl3, 800 rpm, 40 s,

annealed at 200 °C for 10 min. bConcentrations of cast solutions.

The optimum solution concentration was determined as 10 mg mL–1 for C6-DPP–BP:PC61BM among the

examined conditions. The thickness of the active layer deposited at this concentration was 115 nm.

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2:1 2.4 0.55 0.25 0.33

1:1 0.3 0.44 0.28 0.04





160 9.12 0.70 0.48 3.06

180 2.41 0.55 0.25 0.33


40 s, bHeating periods: 30 min for 160 and 180 °C, 10 min for 200 °C.

The optimum annealing temperature was assumed as 160 °C for C8-DPP–BP:PC61BM among the examined

conditions. The thickness of the resulting active layer was 115 nm.


p:n Ratiob JSC (mA cm–2) VOC (V) FF PCE (%)

2:1 0.88 0.66 0.33 0.19

1:1 0.61 0.64 0.34 0.13





160 0.42 0.39 0.30 0.05

180 0.88 0.66 0.33 0.19


40 s, bHeating periods: 30 min for 160 and 180 °C, 10 min for 200 °C.

The optimum annealing temperature was determined as 180 °C for C10-DPP–BP:PC61BM among the

examined conditions. The thickness of the resulting active layer was 115 nm.

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Figure S5. Optical microscope image of a thin film of C2-DPP–BP:PC61BM (2:1) on a PEDOT:PSS-modified

ITO substrate. The scale bar corresponds to 100 m.

Figure S6. J–V curves of the hole-only devices comprising Cn-DPP–BP:PC61BM films: (a) C4-DPP–

BP:PC61BM (h = 2.2 × 10–4 cm2 V–1 s–1); (b) C6-DPP–BP:PC61BM (1.7 × 10–4 cm2 V–1 s–1); C8-DPP–

BP:PC61BM (1.5 × 10–4 cm2 V–1 s–1); C10-DPP–BP:PC61BM (6.0 × 10–5 cm2 V–1 s–1). The fitting lines to the

Mott–Gurney law are shown in red.

L = 80 nm L = 76 nm

SCLC fit

C4-BHJ

L = 79 nm L = 91 nm

SCLC fit

C6-BHJ

SCLC fit

C8-BHJ

SCLC fit

C10-BHJ

(a) (b)

(c) (d)

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Figure S7. Tapping-mode AFM images (left) and cross-section profiles (right) of Cn-DPP–BP:PC61BM films

on glass/PEDOT:PSS substrate. The red lines in the left images show where the profiles were extracted. The

deepest pinhole in scanned area was included in the corresponding cross-section profile in each case.

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Figure S8. Tapping-mode AFM images of neat films on glass/PEDOT:PSS substrate: (a) C4-DPP–BP (RMS

roughness = 5.61 nm); (b) C6-DPP–BP (3.69 nm); (c) C8-DPP–BP (1.23 nm); (d) C10-DPP–BP (5.20 nm).

Figure S9. Absorption spectra of C4-, C6-, C8-, and C10-DPP–BP neat films on glass substrates before (red)

and after (blue) soaking in toluene for 5 min.

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Figure S10. 2D-GIWAXD data of (a) C4-, (b) C6-, (c) C8-, and (d) C10-DPP–BP neat films on

Si/SiO2/PEDOT:PSS substrate: (left) full images; (middle) out-of-plane profiles; (right) in-plane profiles.

Table S14. Diffraction peaks in the 2D-GIWAXD data of Cn-DPP–BP neat films.

Compound

Out-of-plane In-plane

Primary peak – Stacking peak Primary peak – Stacking peak

q (Å–1) d (Å) q (Å–1) d (Å) q (Å–1) d (Å) q (Å–1) d (Å)

C4-DPP–BP – – 1.79 3.51 0.48 13.1 – –

C6-DPP–BP – – 1.79 3.51 0.47 13.4 – –

C8-DPP–BP 0.35 18.0 1.77 3.55 0.34 18.5 1.71 3.67

C10-DPP–BP 0.33 19.0 1.86 3.38 – – 1.74 3.61

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Figure S11. 2D-GIWAXD data of (a) C4-, (b) C6-, (c) C8-, and (d) C10-DPP–BP:PC61BM blend films on

Si/SiO2/PEDOT:PSS substrate: (left) full images; (middle) out-of-plane profiles; (right) in-plane profiles.

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Table S15. Diffraction peaks in the 2D-GIWAXD data of Cn-DPP–BP:PC61BM blend films.

Compounds

Out-of-plane In-plane

Primary peak – Stacking peak Primary peak – Stacking peak

q (Å–1) d (Å) q (Å–1) d (Å) q (Å–1) d (Å) q (Å–1) d (Å)

C4-DPP–BP 0.45 14.0 1.76 3.57 0.48 13.1 1.73 3.63

C6-DPP–BP 0.37 17.0 1.81 3.47 0.36 17.5 1.78 3.53

C8-DPP–BP 0.35 18.0 1.76 3.57 0.34 18.5 1.73 3.63

C10-DPP–BP 0.33 19.0 1.86 3.38 – – 1.72 3.65

Figure S12. Edge-to-edge dimension of the BP framework in the DFT-optimized structures of (a) C4- and

(b) C6-DPP–BP.

Figure S13. DFT-optimized structures of (a) C4-, (b) C6-, (c) C8-, and (d) C10-DPP–BP with their aspect

ratios and molecular orientation in neat films.

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Figure S14. DFT-optimized structures of (a) DRCN5T, (b) DRCN6T, (c) DRCN7T, (d) DRCN8T, and (e)

DRCN9T with their aspect ratio and molecular orientations in neat films.1,2

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Figure S15. DFT-optimized structures of (a) p-DTS(FBTTh2)2, and (b) p-SIDT(FBTTh2)2 with their aspect

ratio and molecular orientations in neat films.3,4 Note that the 2-ethylhexyl groups in the original molecules

were simplified as hexyl groups in the calculations.

Figure S16. Analysis of the 2D-GIWAXD data of a C8-DPP–BP:PC61BM blend film: (a) Scanned area in the

pole-figure analysis for the diffraction from the – stacking; (b) Profile of the pole-figure analysis; (c)

Integrated area for diffraction-intensity analysis; (d) Integrated diffraction-intensity profile.

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Figure S17. Out-of-plane profiles of the 2D-GIWAXD data of (a) C4-, (b) C6-, (c) C8-, and (d) C10- blend

films and the peak analysis by Gaussian fitting.

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2. Experimental

General

All reactions were carried out under argon unless otherwise noted. “Room temperature” (rt) means 15–

25 °C. Flash column chromatography was performed on silica gel purchased from Kanto Chemical (Silica Gel

60N, 60 Å, 40–50 m) and by gel permeation chromatography (GPC) was conducted with a JAI LC-

9225NEXT (JAIGEL-2H-40/JAIGEL-1H-40) at room temperature using ethanol-stabilized chloroform as

eluent. Analytical thin-layer chromatography (TLC) was conducted on Merck 200-m thickness silica gel

plates with a fluorescent indicator. Visualization was accomplished with UV light at 254 or 365 nm.

1H NMR and 13C{1H} NMR spectra were recorded on a JEOL ECX 400P (400 MHz) or ECA 600 (600

MHz) spectrometer at 294 K using tetramethylsilane as internal standard. High-resolution electrospray

ionization (ESI) mass spectra were measured on a JEOL AccuTOF/JMS-T100LC mass spectrometer. High-

resolution matrix-assisted laser desorption/ionization (MALDI) mass spectra were measured on a JEOL

SpiralTOFTM/JMS-S3000 mass spectrometer. UV−vis–NIR absorption spectra in solution were measured on a

JASCO V-670 spectrophotometer, respectively. Spectral grade solvents for absorption measurements were

purchased from Nacalai Tesque Inc. Thermogravimetric analysis (TGA) was carried out on a Seiko Exstar

6000 TG/DTA 6200 instrument under nitrogen gas flow at a heating rate of 10 °C min–1.

Materials

Solvents and chemical reagents for synthesis were reagent grade obtained from commercial sources and

used without further purification unless otherwise noted. N-Bromosuccinimide (NBS) was recrystallized from

hot water. Prepared as described in literature were 3,6-dithiophen-2-yl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-

dione (NH-DPP),5 2,5-dibutyl-3,6-dithiophen-2-yl-pyrrolo[3,4-c]pyrrole-1,4-dione (C4-DPP),6 2,5-dihexyl-

3,6- dithiophen-2-yl-pyrrolo[3,4-c]pyrrol-1,4-dione (C6-DPP),7 3-(5-bromothiophen-2-yl)-2,5-dioctyl-6-

(thiophen-2- yl)-pyrrolo[3,4-c]pyrrole-1,4-dione (7d),8 3-(5-bromothiophen-2-yl)-2,5-didecyl-6-(thiophen-2-

yl)-pyrrolo- [3,4-c]pyrrole-1,4-dione (7e),9 3-(triisopropylsilyl)propiolaldehyde,10 and ethyl 4,7-dihydro-8,8-

dimethyl-4,7- ethano-2H-isoindole-1-carboxylate (1).11 [6,6]- Phenyl-C61-butyric acid methyl ester (PC61BM)

was purchased from Luminescence Technology Crop. and used as received.

Computation

Geometry optimization of the Cn-DPP–BP model compound, in which the linear alkyl groups were

replaced with methyl, was performed using the Gaussian 09 program suite12at the B3LYP/6-31G(d) level of

theory with the tight-conversion criteria and without any symmetry constraint. Vibrational frequencies were

computed at the same level to verify that the optimized structure locates at a minimum.

Single-crystal X-ray crystallography

The sample for making single-crystals of C6-DPP–CP was synthesized from a single stereoisomer of

compound 5 that could be separated by silica-gel column chromatography. Single-crystals of C6-DPP–CP were

obtained from diffusion of n-hexane into a dichloroethane solution. The single-crystal X-ray diffraction data

were collected at 90 K on a Bruker APEX II X-ray diffractometer equipped with a large area CCD detector by

using graphite monochromated Mo-K radiation ( = 0.71073 Å). The diffraction data were solved with the

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SIR-97 program and refined with the SHELX-97 program. CCDC 1491998 contains the crystallographic data

which can be obtained free of charge from the Cambridge Crystallographic Data Centre via

www.ccdc.cam.ac.uk/data_request/cif.

Fabrication and evaluation of photovoltaic cells

Indium–tin oxide (ITO)-patterned glass substrates (20 × 25 mm2, 15 per square) were cleaned by gentle

rubbing with an acetone-soaked wipe for ca. 5 s, sonication in acetone and isopropanol for 10 min each, and

exposure to boiling isopropanol for 10 min. The cleaned substrates were further treated in a UV–O3 cleaner

(UV253 V8, Filgen) for 20 min. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS,

Clevious P VP AI4083) layer was spin-coated at 5000 rpm for 40 s, before thermally annealed at 120 °C for

20 min in air. The thickness of the resulting PEDOT:PSS layer was about 30 nm. The substrates were then

transferred to a N2-filled glovebox (<0.5 ppm of O2 and H2O) for preparation of the active layers. Cn-DPP–

BP:PC61BM blend films were prepared by spin-coating of a Cn-DPP–CP:PC61BM solution, followed by

thermal annealing on a hot plate in the glovebox. Finally, Ca (10 nm, 1 Å s–1) and Al (90 nm, 10 Å s–1) were

vapor-deposited at high vacuum (~10–5 Pa) through a shadow mask that defined an active area of 2 × 2 mm2.

The general device structure was [ITO/PEDOT:PSS (30 nm)/Cn-DPP–BP:PC61BM/Ca (10 nm)/Al (90 nm)].

Current-density–voltage (J–V) curves were measured using a Keithley 2400 source measurement unit

under AM 1.5G illumination at an intensity of 100 mW cm–2 using a solar simulator (CEP-2000TF, Bunko-

Keiki). The external quantum efficiency (EQE) spectra were obtained under illumination of monochromatic

light using the same system. Thickness of active layers was measured using a surface profiler (DektakXT,

Bruker) after the measurements of photovoltaic performance.

Evaluation of hole mobilities by the space-charge-limited method

The hole-only devices for space-charge-limited-current (SCLC) measurements were fabricated as follows:

ITO-patterned glass substrates (20 × 20 mm2, 15 per square) were washed by sonicating sequentially in

detergent (Furuuchi Chemical Semico Clean 53), distilled water, and isopropanol at room temperature for 10

min each, then subjected to UV–O3 treatment (Bioforce Nanoscience, TC-003) at room temperature for 20 min.

The PEDOT:PSS (Clevios P VP AI4083) was spin-coated at 3000 rpm for 30 s in air, before thermal annealing

at 130 °C for 10 min in air. The thickness of the resulting PEDOT:PSS layer was about 30 nm. The substrates

were then transferred to a N2-filled glovebox (<5 ppm of O2 and H2O) for preparation of the organic layers.

The active layers were fabricated by spin-coating of Cn-DPP–CP:PC61BM blend solutions in CHCl3 (for C6-,

C8- and C10-DPP–CP, 10 mg mL–1, p:n = 2:1 (w/w)), or in CHCl3 with 10 vol% CS2 (for C4-DPP–CP, 8.5 mg

mL–1, p:n = 4:3 (w/w)) at 800 rpm for 40 s. The substrates were subjected to heating on a hot plate (220 °C,

10 min for C4-DPP–CP; 200 °C, 10 min for C6-DPP–CP; 160 °C, 30 min for C8-DPP–CP; and 180 °C, 30

min for C10-DPP–CP) to convert the precursors to the corresponding BP derivatives. MoO3 (15-nm thick, 0.5

Å s–1) and Al (80-nm thick, 1 Å s–1) were then vapor-deposited at high vacuum (~10–5 Pa) through a shadow

mask that defined an active area of 1.0 mm2. Finally, each the device was encapsulated with a glass plate and

epoxy resin before taken out from the glove box for the measurement.

The J–V characteristics of the resulting devices were measured in air within the range of 0−10 V using a

Keithley 2400 source-measure unit. The J–V curves were analyzed by the Mott–Gurney law describing SCLC:

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J = (8/9) r 0(V2/L 3)

where r is the relative dielectric constant, 0 is the permittivity of free space, is the hole mobility, V is the

applied voltage, and L is the thickness of the active layer. The dielectric constant r is assumed to be 3, which

is a typical value for organic semiconductors. The active-layer thickness (L) was measured using a surface

profiler (ET200, Kosaka Laboratory) after the SCLC measurements. (80 nm for C4-DPP–BP:PC61BM, 76 nm

for C6-DPP–BP:PC61BM, 79 nm for C8-DPP–BP:PC61BM, and 91 nm for C10-DPP–BP:PC61BM).

Fluorescence-decay measurements of active layers

The light from a picosecond-diode laser (470 nm, 10 MHz, 100 ps FWHM, Picoquant) was introduced to

an inverted microscope (IX71, Olympus) and focused onto an active layer of OPV by an objective lens (× 60,

N.A.: 0.7, LUCPlanFLN, Olympus). The fluorescence from the active layer was collected by the same

objective lens and passed through a confocal pinhole (100 m) and suitable filters.

Measurements of optoelectronic properties of thin films

Thin-film smalples for the photoabsorption and photoelectron spectrometry measurements were prepared

by spin-coating of precursors on glass substrates followed by heating to induce the CP-to-BP conversion. The

employed conditions are as follows:

Precursor Deposition solution Spin coating Heating

CP

C2-DPP–CP

C4-DPP–CP

C6-DPP–CP

C8-DPP–CP

C10-DPP–CP

20 mg mL–1 in CHCl3/chlorobenzene (1:2 v/v)

3.0 mg mL–1 in CHCl3

4.6 mg mL–1 in CHCl3/CS2 (9:1 v/v)




1500 rpm for 30 s

800 rpm for 30 s

800 rpm for 30 s

800 rpm for 30 s

800 rpm for 30 s

800 rpm for 30 s

180 °C for 20 min

200 °C for 10 min

220 °C for 10 min

200 °C for 10 min

160 °C for 30 min

180 °C for 30 min

Ionization energies of the resulting thin films were determined from the onset of photoelectron spectra

measured by a photoelectron spectrometer in air (AC-3, Riken Keiki). UV−vis–NIR absorption spectra of the

thin films were measured on a JASCO V-650 spectrophotometers.

Analysis of surface morphology

The surface morphology of organic films was observed by an SII SPA400/SPI3800N atomic force

microscope in the tapping mode using a silicon probe with a resonant frequency of 138 kHz and a force

constant of 16 N m–1 (SII, SI-DF20).

X-ray diffraction analysis of thin films

Grazing-incidence wide-angle X-ray diffraction (GIWAXD) experiments were conducted at beamline

BL19B2 in SPring-8 (Hyogo, Japan). The X-ray beam was monochromatized by a double-crystal Si(111)

monochromator, and the X-ray energy was 12.398 keV ( = 1 Å). The incident angle was set to 0.12° with a

Huber diffractometer and the sample-to-detector distance was about 174 mm. Diffracted X-ray from samples

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was recorded by an X-ray photon counting pixel detector (PILATUS 300K, Dectris) for 30 s at room

temperature. Samples for GIWAXD measurements were prepared in the same manner as that for OPV devices

on Si/SiO2/PEDOT:PSS substrates.

Synthetic procedures and spectroscopic data

C2-DPP. To a solution of NH-DPP (500 mg, 1.66 mmol) and potassium carbonate (0.92 g, 6.7 mmol, 4.0

equiv) in dehydrated NMP (53 mL) was added iodoethane (1.7 mL, 21 mmol, 13 equiv) in one portion. The

mixture was stirred at rt for 10 min then 70 °C for 5 min, before an additional amount of iodoethane (1.3 mL,

17 mmol, 10 equiv) was added. The mixture was stirred at 70 °C for 2 h, and then another portion of iodoethane

(1.3 mL, 17 mmol, 10 equiv) was added and the mixture was further stirred at 70 °C for 21 h. The mixture was

cooled to room temperature, and distilled water (80 ml) was added. The precipitate was collected by filtration,

washed with methanol (15 mL × 3), dissolved in the minimum amount of CH2Cl2 and re-precipitated by adding

hexanes. The target compound C2-DPP was obtained as a red solid in 75% yield (446 mg, 1.25 mmol). 1H

NMR (400 MHz, CDCl3) : 8.88 (dd, J = 4.0, 1.0 Hz, 2H), 7.64 (dd, J = 5.0, 1.0 Hz, 2H), 7.29 (dd, J = 5.0,

4.0 Hz), 4.16 (q, J = 7.0 Hz, 4H), 1.38 (t, J = 7.0 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) : 161.3, 139.9,

135.1, 130.7, 129.7, 128.7, 107.8, 37.1, 15.1; HRMS (EI) m/z: calcd for C18H16N2O2S2•+ (M•+) 356.0648, found

356.0651.

Compound 7a. A solution of NBS (150 mg, 0.842 mmol, 1.0 equiv) in CHCl3 (25 mL) was added dropwise

to a solution of C2-DPP (300 mg, 0.842 mmol) in CHCl3 (25 mL) at 0 °C over the course of 1 h in the dark.

The reaction was stirred at rt overnight, and the solvent was removed under reduced pressure. The residue was

purified by column chromatography on silica gel (CH2Cl2/hexanes, 2:1) and reprecipitation from a CH2Cl2

solution by adding hexanes to give the target compound 7a as a purple solid in 47% yield (171 mg, 0.393

mmol). 1H NMR (400 MHz, CDCl3): 8.89 (dd, J = 4.0, 1.0 Hz, 1H), 8.64 (d, J = 4.2 Hz, 1H), 7.66 (dd, J =

5.0, 1.0 Hz, 1H), 7.29 (dd, J = 5.0, 4.0 Hz, 1H), 7.24 (d, J = 4.2 Hz, 1H), 4.15 (q, J = 7.2 Hz, 2H), 4.09 (q, J =

7.2 Hz, 2H), 1.37 (t, J = 7.2 Hz, 3H), 1.37 (t, J = 7.2 Hz, 3H); 13C{1H} NMR (100 MHz, CDCl3): 161.2,

161.0, 140.3, 138.4, 135.3, 134.9, 131.6, 131.1, 131.0, 129.6, 128.7, 118.8, 108.0, 107.7, 37.1, 37.1, 15.2, 15.1;

HRMS (EI): m/z calcd for C18H15BrN2O2S2+ ([M + H]+), 433.9753; found, 433.9757.

Compound 7b. A solution of NBS (215 mg, 1.21 mmol, 1.0 equiv) in CHCl3 (25 mL) was added dropwise

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The reaction was stirred at rt overnight, and the solvent was removed under reduced pressure. The residue was

purified by flash column chromatography on silica gel (CH2Cl2/hexanes, 2:1) and reprecipitation from a

CH2Cl2 solution by adding hexanes to give the target compound 7b as a purple solid in 57% yield (337 mg,

0.686 mmol). 1H NMR (400 MHz, CDCl3): 8.94 (dd, J = 4.0, 1.0 Hz, 1H), 8.67 (d, J = 4.0 Hz, 1H), 7.65 (dd,

J = 5.0, 1.0 Hz, 1H), 7.28 (dd, J = 5.0, 4.0 Hz, 1H), 7.23 (d, J = 4.0 Hz, 1H), 4.07 (t, J = 7.8 Hz, 2H), 4.00 (t,

J = 7.8 Hz, 2H), 1.76–1.67 (m, 4H), 1.49–1.40 (m, 4H), 0.98 (t, J = 7.4 Hz, 3H), 0.97 (t, J = 7.4 Hz, 3H);

13C{1H} NMR (100 MHz, CDCl3): 161.3, 161.1, 140.4, 138.5, 135.5, 135.1, 131.5, 131.2, 131.0, 129.7,

128.7, 118.8, 107.9, 107.5, 42.0, 42.0, 32.1, 32.0, 20.2, 13.7; HRMS (EI): m/z calcd for C22H23BrN2O2S2•+

(M•+) 490.0379, found 490.0381.

Compound 7c. A solution of NBS (178 mg, 1.00 mmol, 1.0 equiv) in CHCl3 (17 mL) was added dropwise


The reaction was stirred at rt overnight and the solvent was removed under reduced pressure. The residue was

purified by flash column chromatography on silica gel (CH2Cl2/hexane, 7:3) and then reprecipitation from a

CH2Cl2 solution by adding hexanes to give the target compound 7c as a purple solid in 49% yield (270 mg,

0.493 mmol). 1H NMR (400 MHz, CDCl3): 8.94 (dd, J = 4.0, 1.0 Hz, 1H), 8.67 (d, J = 4.0 Hz, 1H), 7.66 (dd,

J = 5.0, 1.0 Hz, 1H), 7.29 (dd, J = 5.0, 4.0 Hz, 1H), 7.24 (d, J = 4.0 Hz, 1H), 4.06 (t, J = 8.0 Hz, 2H), 3.99 (t,

J =8.0 Hz, 2H), 1.78–1.68 (m, 4H), 1.45–1.27 (m, 12H), 0.91–0.87 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3):

161.3, 161.1, 140.5, 138.6, 135.5, 135.1, 131.6, 131.2, 130.0, 129.8, 128.7, 118.8, 107.9, 107.6, 42.3, 42.2,

31.4, 31.4, 23.0, 29.9, 26.5, 26.5, 22.6, 22.5, 14.0; HRMS (MALDI, DCTB): m/z calcd for C26H33N2O2S2Br

([M + H]+) 547.1083, found 547.1083.

Compound 2. Methylal (4.24 mL, 48.0 mmol, 0.6 equiv) and acetic acid (240 mL) were added to a solution

of compound 1 (19.6 g, 80.0 mmol) in CH2C12 (120 mL). After the addition of conc.H2SO4 (80 drops), the

resulting mixture was stirred at rt for l h. The reaction mixture was quenched by pouring into water, and

extracted with CH2Cl2. The organic layer was washed with sat. NaHCO3 and brine, dried over Na2SO4, and

evaporated under vacuum. The residue was purified by recrystallization in hexanes to give the target compound

2 as a white powder in 79% yield (15.9 g, 31.6 mmol, mixture of stereoisomers). 1H NMR (400 MHz,

CDCl3): 8.43−8.35 (m, 2H), 6.54–6.50 (m, 2H), 6.46–6.42 (m, 2H), 4.37−4.20 (m, 4H), 3.96–3.82 (m, 2H),

S22

3.79–3.77 (m, 2H), 3.51–3.48 (m, 2H), 1.36–1.32 (m, 8H), 1.18–1.14 (m, 2H), 1.05 (s, 6H), 0.73–0.72 (m,

6H); 13C{1H} NMR (100 MHz, CDCl3): 162.1, 137.7, 137.6, 136.0, 135.1, 135.1, 127.2, 127.0, 124.2, 123.9,

114.8, 59.8, 59.8, 46.6, 43.6, 43.6, 37.6, 37.6, 33.6, 30.8, 30.7, 30.3, 30.2, 23.5, 23.5, 14.5 (the number of

signals are less than expected because of overlapping between isomers); HRMS (ESI): m/z calcd for

C31H38N2NaO4+ ([M + Na]+) 525.2724, found 525.2722.

Compound 3. A solution of compound 2 (7.54 g, 15.0 mmol) and NaOH (7.34 g, 184 mmol, 12 equiv) in

(CH2OH)2 (150 mL) was heated at 150 °C for 2 h under argon in the dark. The reaction mixture was quickly

cooled down to rt by using ice bath, poured to water, and extracted with EtOAc. The organic layer was washed

with water and brine, dried over Na2SO4, and concentrated under reduced pressure. The residue was purified

by flash column chromatography on silica gel (CH2Cl2) to give compound 3 as a brown solid in 83% yield

(4.45 g, 12.4 mmol, mixture of stereoisomers). 1H NMR (400 MHz, CDCl3): 7.11 (br, 2H), 6.56–6.52 (m,

2H), 6.45–6.41 (m, 2H), 6.34 (m, 2H), 3.92–3.78 (m, 2H), 3.47–3.43 (m, 2H), 3.17–3.15 (m, 2H), 1.37−1.34

(m, 2H), 1.20−1.17 (m, 2H), 1.03 (s, 6H), 0.76 (s, 6H); 13C{1H} NMR (100 MHz, CDCl3): 137.0, 136.9,

135.1, 135.0, 128.5, 128.3, 124.5, 124.3, 118.5, 118.8, 108.8, 108.6, 46.0, 44.1, 37.0, 33.2, 33.2, 30.9, 30.6,

30.5, 23.1, 23.0 (the number of signals are less than expected because of overlapping between isomers); HRMS

(ESI): m/z calcd for C25H30N2Na+ ([M + Na]+) 381.2301, found 381.2304.

Compound 4. A solution of compound 3 (6.21g, 17.3 mmol) in methanol (1.71 L) was deoxygenated by

argon bubbling for 20 min, before 3-(triisopropylsilyl)propiolaldehyde (5.0 ml, 14 mmol, 1.1 equiv) was added.

The reaction system was covered with aluminum foil, and boron trifluoride etherate (BF3·OEt2) (0.29 ml, 2.4

mmol) was added dropwise to the solution. The resulting mixture was stirred overnight at rt, to which 2,3-

dichloro-5,6-dicyano-p-benzoquinone (7.76 g, 34.2 mmol, 2.0 equiv) was added. The reaction was further

stirred for 8 h at rt before the solvent was removed under reduced pressure. The residue was purified by flash

column chromatography on silica gel (CH2Cl2). The resulting solid was washed and filtered with CH2Cl2 (200

mL) to leave poorly soluble stereoisomers of compound 4 as a purple powder in 9% yield (0.798 g, 0.729

mmol). The filtrate was reprecipitated (CH2Cl2/MeOH) to give soluble stereoisomers of compound 4 as a

purple powder in 34% yield (3.16 g, 3.61 mmol). Only the soluble stereoisomers of 4 were used in the next

step. 1H NMR (400 MHz, CDCl3): 10.20–10.17 (m, 2H), 7.21–7.10 (m, 8H), 6.08–6.01 (m, 4H), 5.59–5.54

(m, 4H), 2.05–1.96 (m, 4H), 1.78–1.43 (m, 58H), 0.72–0.57 (m, 12H), –2.62– –2.72 (m, 2H); 13C{1H} NMR

(100 MHz, CDCl3): 150.4, 150.4, 150.3, 150.3, 150.2, 149.3, 149.3, 149.2, 149.3, 144.1, 143.9, 143.8, 138.2,

138.1, 138.1, 136.2, 136.1, 136.0, 136.0, 135.3, 135.2, 135.1, 135.1, 109.5, 100.3, 98.8, 98.8, 97.6, 97.4, 50.9,

S23

50.8, 50.8, 50.8, 44.4, 40.5, 40.5, 40.5, 40.5, 40.4, 40.4, 37.6, 31.1, 31.0, 30.9, 30.9, 30.6, 30.5, 30.4, 30.4,

30.2, 19.3, 19.1, 19.1, 12.6, 12.59, 12.3, 12.3, 12.3 (the number of signals are less than expected because of

overlapping between isomers); UV−vis (CH2Cl2): max ( × 104) 663 (1.79), 605 (0.847), 578 (4.91), 537 (1.20),

423 (23.5); HRMS (ESI): m/z calcd for C74H95N4Si2+ ([M + H]+) 1095.7090, found 1095.7090.

Compound 5. A solution of Zn(OAc)2·2H2O (2.52 g, 11.5 mmol, 5.0 equiv) in methanol (25 ml) was added

to a solution of 4 (2.51 g, 2.29 mmol) in CH2Cl2 (200 ml). After stirring at rt for 2 h, the reaction mixture was

washed with sat. NaHCO3 aq. and water, dried over Na2SO4, and evaporated under reduced pressure. The

residue was purified by flash column chromatography on silica gel (CH2Cl2/hexane, 1:2, Rf = 0.42 (2nd spot*))

followed by reprecipitation from a CH2Cl2 solution by adding MeOH to give compound 5 as a purple powder

in 49% yield (1.31 g, 1.13 mmol). *There were two other spots containing isomers of compound 5 at Rf = 0.55

and 0.19; however, they showed considerably lower solubilities than the 2nd spot, and their amounts were small.

Accordingly, only the 2nd spot was used in the next step. 1H NMR (400 MHz, CDCl3): 10.18 (s, 2H), 7.24–

7.12 (m, 8H), 6.24–6.16 (m, 4H), 5.58–5.52 (m, 4H), 2.03–1.96 (m, 4H), 1.81–1.42 (m, 58H), 0.71–0.48 (m,

12H); 13C{1H} NMR (100 MHz, CDCl3): 151.3, 151.2, 151.1, 151.1, 150.6, 150.6, 150.5, 146.7, 146.7, 146.5,

146.5, 140.6, 140.5, 140.5, 138.4, 138.4, 138.3, 135.4, 135.3, 135.1, 135.1, 110.8, 110.3, 102.2, 99.8, 99.5,

99.5, 98.9, 98.5, 51.7, 51.7, 44.6, 44.5, 40.6, 40.5, 40.5, 40.4, 37.6, 37.5, 37.5, 31.1, 31.1, 30.9, 30.9, 30.7,

30.5, 30.5, 30.4, 19.3 19.1, 12.7, 12.4 (the number of signals are less than expected because of overlapping

between isomers); UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 613 (3.68), 572 (1.52), 438 (39.7); HRMS

(ESI): m/z calcd for C74H93N4Si2Zn+ ([M + H]+) 1157.6225, found 1157.6229.

Compound 6. Tetrabutylammonium fluoride (1.0 M in THF, 3.6 mL, 3.6 mmol, 6.0 equiv) was added to a

solution of compound 5 (700 mg, 0.604 mmol) in dehydrated CH2Cl2 (60 ml) under argon. After refluxing for

2 h, the mixture was washed with sat. NaHCO3 aq. and water. The organic layer was dried over Na2SO4 and

concentrated under reduced pressure. The residue was purified by flash column chromatography on silica gel

S24

(CH2Cl2) and reprecipitation from a CH2Cl2 solution by adding hexanes to give compound 6 as a purple powder

in 97% yield (496 mg, 0.586 mmol). 1H NMR (600 MHz, CDCl3): 10.23–10.22 (m, 2H), 7.21–7.08 (m, 8H),

6.14–6.12 (m, 4H), 5.60–5.53 (m, 4H), 4.41–4.40 (m, 2H), 2.08–2.05 (m, 4H), 1.80–1.75 (m, 4H), 1.52–1.48

(m, 12H), 0.83–0.78 (m, 12H); 13C{1H} NMR (151 MHz, CDCl3): 151.2, 151.2, 151.2, 151.2, 150.9, 150.9,

150.9, 150.8, 146.2, 146.2, 146.2, 146.2, 141.0, 140.9, 140.9, 140.9, 138.5, 135.3, 135.3, 99.4, 97.0, 96.9, 88.2,

88.1, 87.2, 86.9, 52.2, 52.2, 52.1, 52.1, 44.3, 44.2, 40.7, 40.6, 40.6, 37.5, 31.6, 31.6, 30.8, 30.8, 30.7, 30.7 (the

number of signals are less than expected because of overlapping between isomers); HRMS (ESI): m/z calcd

for C56H53N4Zn+ ([M + H]+) 845.3556, found 845.3554.

C2-DPP–BP. A solution of compound 6 (100 mg, 118 mol) and compound 7a (103 mg, 236 mol, 2.0

equiv) in dehydrated toluene (20 mL) and Et3N (10 mL) was deoxygenated by three cycles of freeze–pump–

thaw. PdCl2(PPh3)2 (16.6 mg, 23.7 mol, 20 mol%) and CuI (9.0 mg, 47 mol, 40 mol%) were added under

the protection of argon. After stirring at 70 °C for 23 h, the solvent was removed under reduced pressure. The

residue was purified by flash column chromatography on silica gel (CHCl3, Rf = 0.23) to give a crude product

of C2-DPP–ZnCP (127 mg), which was extremely low in solubility and thus subjected the dezincification

reaction without further purification. Trifluoroacetic acid (1.0 mL, 13 mmol, large excess) was added to a

solution of the crude C2-DPP–ZnCP (127 mg) in CH2Cl2. After stirring at rt for 2 h, the mixture was washed

with NaHCO3 aq. twice. The organic layer was then dried over Na2SO4 and evaporated under reduced pressure.

The residue was purified by flash silica gel column chromatography on silica gel (EtOAc/hexanes, 3:7; Rf =

0.17) and reprecipitation from a CHCl3 solution by adding hexanes to give C2-DPP–CP as a black powder in

49% yield (86.6 mg, 58.0 mol). 1H NMR (400 MHz, CDCl3): 10.21 (s, 2H), 9.35–9.34 (m, 2H), 9.00–8.98

(m, 2H), 7.98–7.96 (m, 2H), 7.71–7.69 (m, 2H), 7.36–7.33 (m, 2H), 7.22–7.10 (m, 8H), 5.95–5.93 (m, 4H),

5.60–5.56 (m, 4H), 4.39–4.34 (m, 4H), 4.29–4.23 (m, 4H), 2.13–2.10 (m, 4H), 1.86–1.80 (m, 4H), 1.60–1.55

(m, 18H), 1.47–1.44 (m, 6H), 0.93–0.91 (m, 12H), –2.50– –2.52 (m, 2H); 13C NMR spectrum could not be

measured because of the low solubility; UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 728 (14.6), 649 (10.1),

547 (8.34), 423 (9.14), 303 (4.24); HRMS (ESI): m/z calcd for C92H83N8O4S4+([M + H]+) 1491.5415, found

1491.5415.

S25

General procedure for the preparation of C4-, C6-, C8-, and C10-DPP–ZnCP. A solution of compound

6 and compound 7b–7e (2.0 equiv) in toluene/Et3N (2:1 vol.) was deoxygenated by either three cycles of

freeze–pump–thaw or argon bubbling for 20 min. PdCl2(PPh3)2 and CuI were added under the protection of

argon. After stirring at 70 °C overnight, the solvent was removed under reduced pressure. The residue was

purified by flash column chromatography on silica gel and reprecipitation from a CHCl3 solution by adding

hexanes to give the corresponding target compound (C4-, C6-, C8- or C10-DPP–ZnCP).

C4-DPP–ZnCP. The reaction of 6 (180 mg, 213 mol), 7b (209 mg, 426 mol, 2.0 equiv), PdCl2(PPh3)2

(29.9 mg, 42.6 mol, 20 mol%), and CuI (16.2 mg, 85.2 mol, 40 mol%) was carried out in dehydrated toluene

(36 mL) and Et3N (18 mL) following the general procedure. The reaction mixture was purified by flash column

chromatography on silica gel (CHCl3; Rf = 0.16) and reprecipitation to give C4-DPP–ZnCP with a small

amount of impurities as a black solid in 69% yield (244 mg, 146 mol). The impurities could not be removed

by silica-gel column chromatography, gel-permeation chromatography (GPC), and reprecipitation; thus the

product was used in the next step without further purification. 1H NMR (400 MHz, THF-d8): 10.21 (s, 2H),

9.45–9.43 (m, 2H), 9.17–9.15 (m, 2H), 8.04–8.03 (m, 2H), 7.85–7.82 (m,2H), 7.33–7.30 (m, 2H), 7.24–7.20

(m, 4H), 7.10–7.06 (m, 4H), 6.08–6.07 (m, 4H), 5.61–5.55 (m, 4H), 4.29–4.26 (m, 4H), 4.20–4.15 (m, 4H),

2.07–2.04 (m, 4H), 1.93–1.86 (m, 4H), 1.75–1.71 (m, 12H), 1.16–1.54 (m, 16H), 1.08–1.02 (m, 6H), 0.99–

0.95 (m, 6H), 0.87–0.83 (m, 12H); UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 715 (14.4), 562 (11.4), 438

(10.5), 304 (4.18); HRMS (ESI): m/z: calcd for C100H96N8O4S4Zn•+ (M•+) 1664.5723, found 1664.5700.

C6-DPP–ZnCP. The reaction of compound 6 (200 mg, 236 mol), 7c (258 mg, 472 mol, 2.0 equiv),

S26

PdCl2(PPh3)2 (16.6 mg, 23.6 mol, 10 mol%) and CuI (9.0 mg, 47.2 mol, 20 mol%) was carried out in

dehydrated toluene (40 mL) and Et3N (20 mL) following the general procedure. The reaction mixture was

purified by flash column chromatography on silica gel (CH2Cl2/hexane, 2:1; Rf = 0.31) and reprecipitation to

give C6-DPP–ZnCP with a small amount of impurities as a black solid in 67% yield (281 mg, 158 mol). The

impurities could not be removed by silica-gel column chromatography, gel-permeation chromatography, and

reprecipitation; thus it was used in the next step without further purification. 1H NMR (400 MHz, CDCl3 with

1 drop of pyridine): 10.66 (s, 2H), 9.82–9.80 (m, 2H), 9.52–9.50 (m, 2H), 8.28–8.24 (m, 2H), 7.99–7.98 (m,

2H), 7.49–7.41 (m, 4H), 7.40–7.37 (m, 2H), 7.29–7.24 (m, 4H), 6.46–6.40 (m, 4H), 5.76–5.73 (m, 4H), 4.46–

4.42 (m, 4H), 4.30–4.27 (m, 4H), 2.15–2.06 (m, 8H), 1.93–1.78 (m, 8H), 1.73–1.62 (m, 16H), 1.48–1.37 (m,

12H), 1.33–1.26 (m, 8H), 1.09–1.05 (m, 12H), 0.95–0.85 (m, 12H); UV−vis (CHCl3): max [nm] ( [104 M–1

cm–1]) 712 (14.1), 564 (11.5), 441 (10.4), 304 (4.16); HRMS (ESI): m/z calcd for C108H112N8O4S4Zn•+ (M•+)

1776.6975, found 1776.6989.

C8-DPP–ZnCP. The reaction of compound 6 (100 mg, 118 mol), 7d (142 mg, 236 mol, 2.0 equiv),

PdCl2(PPh3)2 (16.6 mg, 23.6 mol, 20 mol%), and CuI (9.0 mg, 47.3 mol, 40 mol%) was carried out in


purified by flash column chromatography on silica gel (CH2Cl2/hexane, 2:1 then CH2Cl2), GPC (CHCl3), and

reprecipitation to give C8-DPP–ZnCP with a small amount of impurities as a black solid in 65% yield (145

mg, 76.4 mol). The impurities could not be removed by silica-gel column chromatography, GPC, and

reprecipitation; thus the product was used in the next step without further purification. 1H NMR (600 MHz,

THF-d8): 10.21 (s, 2H), 9.45–9.44 (m, 2H), 9.17–9.16 (m, 2H), 8.04 (m, 4H), 7.85–7.83 (m, 2H), 7.32–7.30

(m, 4H), 7.10–7.70 (m, 4H), 6.08–6.07 (m, 4H), 5.59–5.57 (m, 4H), 4.28–4.25 (m, 4H), 4.17–4.15 (m, 4H),

2.06–2.04 (m, 4H), 1.94–1.88 (m, 4H), 1.79–1.72 (m, 8H), 1.58–1.53 (m, 16H), 1.47–1.24 (m, 36H), 0.88–

0.82 (m, 24 H); UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 716 (14.4), 563 (11.6), 438 (10.4), 304 (4.28);

HRMS (ESI): m/z calcd for C116H128N8O4S4Zn•+ (M•+) 1888.8227, found 1888.8175.

C10-DPP–ZnCP. The reaction of compound 6 (70 mg, 82.7 mol), 7e (109 mg, 165 mol, 2.0 equiv),

PdCl2(PPh3)2 (11.6 mg, 16.5 mol, 20 mol%), and CuI (6.3 mg, 33.1 mol, 40 mol%) was carried out in


purified by flash column chromatography on silica gel (CH2Cl2/hexane, 2:1 then CH2Cl2) and reprecipitation

to give C10-DPP–ZnCP with a small amount of impurities as a black solid in 62% yield (103 mg, 51.4 mol).

The impurities could not be removed by flash column chromatography, GPC, and reprecipitation; thus the

product was used in the next step without further purification. 1H NMR (400 MHz, THF-d8): 10.21 (s, 2H),

9.46–9.44 (m, 2H), 9.18–9.17 (m, 2H), 8.05–8.04 (m, 2H), 7.85–7.83 (m, 2H) 7.33–7.30 (m, 2H), 7.23–7.20

(m, 4H), 7.10–7.06 (m, 4H), 6.08–6.07 (m, 4H), 5.61–5.55 (m, 4H), 4.29–4.25 (m, 4H), 4.18–4.15 (m, 4H),

2.07–2.04 (m, 4H), 1.96–1.87 (m, 4H), 1.80–1.70 (m, 8H), 1.61–1.51 (m, 12H), 1.49–1.19 (m, 56H), 0.87–

0.79 (m, 24H); HRMS (ESI): m/z calcd for C124H144N846S4ZnNa ([M + Na]+) 2023.9377; found, 2023.9432.

General procedure for the preparation of C4-, C6-, C8-, and C10-DPP–CP. An excess amount of

trifluoroacetic acid was added to a solution of C4-, C6-, C8- or C10-DPP–ZnCP in CH2Cl2. After stirring at rt

for 1 h, the mixture was washed with NaHCO3 aq. (× 2). The organic layer was dried over Na2SO4, and the

solvent was removed under reduced pressure. The residue was purified by flash silica gel column

S27

chromatography on silica gel and reprecipitation from a CHCl3 solution by adding hexanes to give C4-, C6-,

C8- or C10-DPP–CP.

C4-DPP–CP. C4-DPP–ZnCP (100 mg, 60.0 mol) was reacted with trifluoroacetic acid (0.5 mL) in

CH2Cl2 (20 mL) following the general procedure. The reaction mixture was purified by flash column

chromatography on silica gel (CHCl3; Rf = 0.32) and reprecipitation to give C4-DPP–CP as a black solid in

56% yield (53.5 mg, 33.4 mol). 1H NMR (400 MHz, CDCl3): 10.21 (s, 2H), 9.40–9.38 (m, 2H), 9.04–9.01

(m, 2H), 7.98–7.97 (m, 2H), 7.70–7.68 (m, 2H), 7.35–7.32 (m, 2H), 7.22–7.11 (m, 8H), 5.93–5.91 (m, 4H),

5.61–5.55 (m, 4H), 4.29–4.25 (m, 4H), 4.20–4.14 (m, 4H), 2.13–2.09 (m, 4H), 1.98–1.89 (m, 4H), 1.86–1.77

(m, 8H), 1.67–1.47 (m, 20H), 1.10–1.07 (m, 6H), 1.05–1.01 (m, 6H), 0.92–0.89 (m, 12H), –2.50– –2.52 (m,

2H); 13C{1H} NMR (151 MHz, CDCl3): 161.5, 161.4, 161.4, 150.8, 150.8, 149.1, 143.0, 140.3, 139.0, 138.0,

136.9, 136.6, 136.6, 135.7, 135.7, 135.4, 135.2, 132.2, 131.1, 130.5, 130.5, 129.8, 129.7, 128.8, 108.8, 108.0,

103.5, 100.1, 92.2, 91.9, 51.6, 51.5, 51.4, 51.4, 43.9, 43.9, 43.9, 43.9, 42.1, 40.7, 40.7, 40.7, 37.6, 32.5, 32.5,

32.1, 31.6, 31.6, 31.6, 31.0, 30.9, 30.9, 20.4, 20.2, 13.9, 13.8 (the number of signals are less than expected

because of overlapping between isomers); UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 725 (12.7), 655

(10.4), 551 (9.69), 457 (9.46), 432 (9.01), 303 (4.58); HRMS (ESI): m/z calcd for C100H99N8O4S4 ([M + H]+)

1603.6667, found 1603.6666.



chromatography on silica gel (CH2Cl2), GPC (CHCl3), and reprecipitation to give C6-DPP–CP as a black solid

in 72% yield (105 mg, 61.2 mol). 1H NMR (400 MHz, CDCl3): 10.21 (s, 2H), 9.40–9.38 (m, 2H), 9.04–

9.01 (m, 2H), 7.98–7.97 (m, 2H), 7.70–7.68 (m, 2H), 7.35–7.32 (m, 2H), 7.22–7.11 (m, 8H), 5.93–5.92 (m,

4H), 5.61–5.55 (m, 4H), 4.28–4.24 (m, 4H), 4.18–4.13 (m, 4H), 2.13–2.10 (m, 4H), 1.98–1.91 (m, 4H), 1.86–

1.80 (m, 8H), 1.62–1.55 (m, 16H), 1.51–1.36 (m, 20H), 0.95–0.89 (m, 24H), –2.50– –2.52 (m, 2H); 13C{1H}

NMR (100 MHz, CDCl3): 161.3, 161.2, 161.1, 161.1, 150.8, 150.8, 150.7, 149.1, 149.0, 149.0, 149.0, 143.1,

143.0, 140.2, 140.0, 138.9, 138.8, 138.1, 138.0, 138.0, 137.9, 136.8, 136.8, 136.7, 136.6, 136.6, 135.6, 135.5,

135.4, 135.4, 135.3, 135.2, 132.1, 131.0, 130.9, 130.5, 130.4, 129.7, 129.6, 129.6, 128.7, 128.6, 108.7, 108.6,

107.9, 107.7, 103.5, 103.4, 100.1, 96.8, 96.7, 92.2, 91.9, 51.5, 51.5, 51.4, 51.4, 44.0, 43.9, 43.9, 42.6, 42.3,

42.2, 40.7, 40.7, 40.7, 37.6, 31.6, 31.6, 31.4, 31.4, 31.2, 31.0, 30.9, 30.5, 30.4, 29.9, 29.9, 26.8, 26.6, 26.5,

22.7, 22.6, 14.1, 14.1 (the number of signals are less than expected because of overlapping between isomers);

UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 727 (14.4), 650 (10.6), 549 (8.94), 424 (9.57), 304 (4.53);

HRMS (ESI): m/z calcd for C108H115N8O4S4 ([M + H]+), 1715.7919, found 1715.7910.


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chromatography on silica gel (CH2Cl2/hexanes, 2:1) and reprecipitation to give C8-DPP–CP as a black solid

in 87% yield (83.9 mg, 45.9 mol). 1H NMR (400 MHz, CDCl3): 10.21 (s, 2H), 9.40–9.37 (m, 2H), 9.03–

8.99 (m, 2H), 7.98–7.97 (m, 2H), 7.70–7.67 (m, 2H), 7.34–7.31 (m, 2H), 7.22–7.11 (m, 8H), 5.93–5.91 (m,

4H), 5.61–5.55 (m, 4H), 4.28–4.23 (m, 4H), 4.18–4.11 (m, 4H), 2.13–2.10 (m, 4H), 1.99–1.88 (m, 4H), 1.88–

1.75 (m, 8H), 1.58–1.29 (m, 52H), 0.93–0.85 (m, 24H), –2.50– –2.52 (m, 2H); 13C{1H} NMR (100 MHz,

CDCl3): 161.4, 161.3, 161.2, 150.9, 150.8, 149.1, 149.1, 149.0, 143.1, 143.0, 140.2, 139.0, 138.9, 138.0,

138.0, 138.0, 136.9, 136.8, 136.7, 136.6, 136.6, 135.7, 135.6, 135.4, 135.4, 135.3, 135.2, 132.2, 131.1, 131.0,

130.5, 130.5, 129.8, 129.7, 129.6, 129.6, 128.8, 128.7, 108.8, 108.7, 108.0, 107.9, 103.5, 103.4, 100.1, 96.8,

92.2, 91.9, 51.6, 51.5, 51.4, 51.4, 44.0, 43.9, 43.9, 42.6, 42.4, 42.3, 40.7, 40.7, 40.7, 37.6, 31.9, 31.8, 31.6,

31.6, 31.6, 31.1, 31.0, 30.9, 30.9, 30.5, 30.0, 30.0, 29.5, 29.3, 29.2, 27.2, 26.9, 26.9, 22.7, 14.1, 14.1 (the

number of signals are less than expected because of overlapping between isomers); UV−vis (CHCl3): max

[nm] ( [104 M–1 cm–1]) 728 (14.6), 649 (10.5), 548 (8.58), 423 (9.45), 304 (4.38); HRMS (ESI): m/z calcd for

C116H131N8O4S4 ([M + H]+) 1827.9171, found 1827.9180.

C10-DPP–CP. C10-DPP–ZnCP (40.0 mg, 20.0 mol) was reacted with trifluoroacetic acid (0.5 mL) in


chromatography on silica gel (CH2Cl2/hexanes, 2:1) and reprecipitation to give C10-DPP–CP as a black solid

in 90% yield (35.0 mg, 18.0 mol). 1H NMR (400 MHz, CDCl3): 10.22 (s, 2H), 9.40–9.37 (m, 2H), 9.03–

9.00 (m, 2H), 7.98–7.97 (m, 2H), 7.70–7.68 (m, 2H), 7.35–7.31 (m, 2H), 7.22–7.11 (m, 8H), 5.93–5.92 (m,

4H), 5.61–5.56 (m, 4H), 4.28–4.23 (m, 4H), 4.18–4.12 (m, 4H), 2.13–2.09 (m, 4H), 1.98–1.89 (m, 4H), 1.86–

1.77 (m, 8H), 1.58–1.25 (m, 68H), 0.93–0.92 (m, 24H), –2.44– –2.59 (m, 2H); 3C{1H} NMR (100 MHz,

CDCl3): 161.4, 161.3, 161.3, 161.3, 150.9, 150.8, 150.8, 149.1, 149.1, 149.1, 149.1, 143.1, 143.0, 140.3,

140.2, 139.0, 139.0, 138.1, 138.0, 138.0, 137.9, 136.8, 136.7, 136.6, 136.6, 135.7, 135.6, 135.4, 135.4, 135.3,

135.2, 132.2, 131.1, 131.0, 130.5, 130.5, 129.8, 129.7, 129.7, 129.6, 128.8, 128.7, 108.8, 108.7, 108.0, 107.9,

103.5, 103.4, 100.1, 96.8, 92.2, 91.9, 51.6, 51.5, 51.5, 44.0, 44.0, 43.9, 43.0, 42.4, 42.3, 40.7, 40.7, 37.6, 31.9,

31.9, 31.6, 31.6, 31.6, 31.1, 31.0, 30.9, 30.9, 30.5, 30.5, 30.0, 30.0, 29.7, 29.6, 29.6, 29.5, 29.3, 29.3, 27.2,

26.9, 22.7, 22.7, 14.2, 14.1 (the number of signals are less than expected because of overlapping between

isomers); UV−vis (CHCl3): max [nm] ( [104 M–1 cm–1]) 728 (14.6), 649 (10.5), 548 (8.57), 423 (9.42), 304

(4.36); HRMS (ESI): m/z calcd for C124H147N8O4S4 ([M + H]+) 1940.0423, found 1940.0435.

General procedure of the retro-Diels−Alder reactions of C2-, C4-, C6-, C8-, and C10-DPP–CP. C2-,

C4-, C6-, C8-, and C10-DPP–CP were heated at 200 °C for 1 h in sample tubes under reduced pressure to give

the corresponding products (C2-, C4-, C6-, C8-, and C10-DPP–BP) as black solids. The products were

essentially insoluble in organic solvents, and thus identified only by mass spectrometry.

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C2-DPP–BP. HRMS (MALDI–TOF, DCTB): m/z calcd for C76H50N8O4S4 (M•+) 1266.2832, found

1266.2832.


1378.4089.


1490.5331.

C8-DPP–BP. HRMS (MALDI–TOF, DCTB): m/z calcd for C100H98N8O4S4 (M•+) 1602.6588; found

1602.6586.


1714.7830.

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3. Absorption spectra in solution

Figure S18. Absorption spectra of C4, C6, C8, and C10-DPP–ZnCP in CHCl3.

Figure S19. Absorption spectra of C2, C4, C6, C8, and C10-DPP–CP in CHCl3.

S31

4. NMR spectra

Figure S20. 1H NMR spectrum of C2-DPP in CDCl3.

Figure S21. 13C NMR spectrum of C2-DPP in CDCl3.

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Figure S22. 1H NMR spectrum of 7a in CDCl3.

Figure S23. 13C NMR spectrum of 7a in CDCl3.

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Figure S24. 1H NMR spectrum of 7b in CDCl3.

Figure S25. 13C NMR spectrum of 7b in CDCl3.

S34

Figure S26. 1H NMR spectrum of 7c in CDCl3.

Figure S27. 13C NMR spectrum of 7c in CDCl3.

S35

Figure S28. 1H NMR spectrum of 2 in CDCl3.

Figure S29. 13C NMR spectrum of 2 in CDCl3.

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S37



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S39



S40

Figure S38. 1H NMR spectrum of C4-DPP–ZnCP in THF-d8.

Figure S39. 1H NMR spectrum of C6-DPP–ZnCP in CDCl3 (1 drop pyridine).

S41

Figure S40. 1H NMR spectrum of C8-DPP–ZnCP in THF-d8.

Figure S41. 1H NMR spectrum of C10-DPP–ZnCP in CDCl3.

S42

Figure S42. 1H NMR spectrum of C2-DPP–CP in CDCl3.


S43

Figure S44. 13C NMR spectrum of C4-DPP–CP in CDCl3.


S44



S45



S46


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