Supporting Information

© Wiley-VCH 2008

69451 Weinheim, Germany

S1

Supporting Information for

Towards Fluorescent Memories with Nondestructive Readout:

Photoswitching of Fluorescence by Intramolecular Electron Transfer in a

Diarylethene-Perylene Bisimide Photochromic System

Martin Berberich, Ana-Maria Krause, Michele Orlandi, Franco Scandola,* and Frank

Würthner*

M. Berberich, A.-M. Krause, Prof. Dr. F. Würthner, Universität Würzburg, Institut für Organische

Chemie, Am Hubland, D-97074 Würzburg, Germany. E-mail: wuerthner@chemie.uni-wuerzburg.de;

M. Orlandi, Prof. Dr. F. Scandola, Università di Ferrara, Dipartimento di Chimica, 44100 Ferrara,

Italy. E-mail: snf@unife.it

Table of Contents

1. Materials and Methods S2

2. Synthesis and Characterisation S4

3. Fluorescence Measurements S12

4. UV/Vis Absorption and Fluorescence Spectra S13

5. Cyclic Voltammetry Studies S15

6. Lifetime Measurements S17

7. Femtosecond Transient Absorption Spectroscopy S17

8. Spectroelectrochemistry S18

9. Excitation Spectrum S19

10. Additional References S20

S2

1. Materials and Methods

All solvents and reagents were purchased from commercial sources and used as received

without further purification, unless otherwise stated. N,N´-Dicyclohexyl-1,7-dipyrrolidinyl-

perylene-3,4:9,10-tetracarboxylic acid bisimide (2)[S1], 1,7-dipyrrolidinylperylene-3,4:9,10-

tetracarboxylic acid bisanhydride[S1] and 1,2-bis-(2-methylbenzo[b]thiophen-3-yl)-perfluoro-

cyclopentene[S2] were prepared according to literature procedures. Column chromatography

was performed using silica gel Si60 (0.035–0.070 mm) from Acros Organics.

Melting points were determined on an Olympus Bx41 polarization microscope and are

uncorrected. 1H NMR spectra were recorded on Bruker Advance 400 or Bruker Advance

DMX 600 and calibrated to the internal standard TMS or the residual solvent peak. High

resolution mass spectra (APCI and ESI) were recorded on an ESI MicrOTOF Focus from

Bruker Daltonics. Elemental analyses were performed on a CHNS 932 analyzer (Leco

Instruments GmbH, Mönchengladbach, Germany) in the Analysis Division of the Institute of

Inorganic Chemistry, University of Würzburg. The UV irradiation was performed by a

Rayonet Photoreactor RPR-100 (Southern New England Ultraviolet Company) with 16 UV

lamps (each 24 Watt; λmax = 350 nm or 21 Watt; λmax = 300 nm). A L42 filter from JASCO

Corporation (L42_.SP - 08.08.03 - 0.1 mm cuvette) was used for filtering irradiation below

400 nm.

For all spectroscopic measurements, spectroscopic grade solvents (Uvasol) from Merck

(Hohenbrunn, Germany) were used. UV/Vis spectra were recorded on a Perkin Elmer UV/Vis

spectrometer Lamda 40P and fluorescence spectra with a PTI QM-4/2003. All fluorescence

measurements were performed under aerobic conditions and fluorescence spectra are

corrected against photomultiplier and lamp intensity. The fluorescence quantum yields were

determined as the average value for three different excitation wavelengths using N,N’-bis

(2,6-diisopropylphenyl)-1,6,7,12-tetraphenoxyperylene-3,4:9,10-tetracarboxylic acid bisimide

as reference (Φfl = 0.96 in chloroform) by applying the high dilution method (Abs. < 0.05).[S3]

S3

Emission lifetimes were measured using a TCSPC apparatus (PicoQuant Picoharp300)

equipped with sub-nanosecond LED sources (280-600 nm range, 500-700 ps pulsewidth)

powered with a PicoQuant PDL 800-B variable (2.5-40 MHz) pulsed power supply. The

decays were analyzed by means of PicoQuant FluoFit Global Fluorescence Decay Analysis

Software.

Femtosecond time-resolved experiments were performed using a pump-probe setup[S4] based

on the Spectra-Physics Hurricane Ti:sapphire laser source and the Ultrafast Systems Helios

spectrometer. The 400 nm and 680 nm pump pulses were generated with a Spectra Physics

800 OPA. Probe pulses were obtained by continuum generation on a sapphire plate (useful

spectral range, 450-800 nm). Effective time resolution ca. 300 fs, temporal chirp over the

white-light 450-750 nm range ca. 200 fs, temporal window of the optical delay stage

0-1000 ps. The time-resolved spectral data were analyzed with the Ultrafast Systems Surface

Explorer Pro software.

Cyclic voltammetry was performed on a standard commercial electrochemical analyzer (EC

epsilon; BAS Instruments, UK) in a three electrode single-compartment cell under argon.

Dichloromethane (HPLC grade) was dried over calcium hydride under argon and degassed

prior to use. The supporting electrolyte tetrabutylammonium hexafluorophosphate (TBAHFP)

was synthesized according to literature,[S5] recrystallized from ethanol/water and dried in high

vacuum. The measurements were carried out under exclusion of air and moisture at a

concentration of about 10–4 M with ferrocene as internal standard for the calibration of the

potential. Working electrode: Pt disc; reference electrode: Ag/AgCl; auxiliary electrode: Pt

wire.

The spectroelectrochemistry measurements were carried out on a Jasco V-570 UV/Vis/NIR

spectrophotometer in transmission mode. For this purpose, a solution of the supporting

electrolyte tetrabutylammonium hexafluorophosphate (TBAHFP) and dye 2 were transferred

S4

into a thin-layer cell (optical path 1 mm) with a platinum mini-grid as the working electrode, a

platinum wire as the counter electrode and a silver wire as the reference electrode.

The quantum yield for the cyclization was obtained by irradiating the open PBI-DAE 1o at

350 nm with a Xe lamp equipped with a monochromator, slit 20 nm. The intensity of the

incident radiation was measured with a Newport multifunction optical meter Model 1835-C

and a Newport Model 818 UV probe.

The geometries of 1o and 1c were optimized using MM3 force field with the parameter given

in CaChe quantum CaChe workspace 5.04.

2. Synthesis and Characterisation

N,N’-Di(1-undecyldodecyl)-1,7-dipyrrolidinylperylene-3,4:9,10-tetracarboxylic acid

bisimide (4)

A mixture of 1,7-dipyrrolidinylperylene-3,4:9,10-tetracarboxylic acid bisanhydride (47.0 mg,

88.6 μmol), 1-undecyldodecylamine (68.0 mg, 200 μmol), and imidazole (800 mg) was

heated to 105 °C under a nitrogen gas atmosphere for 13 h. After being cooled to room

temperature, 5 mL ethanol, 20 mL dichloromethane, and 15 mL 2 N HCl were successively

added to the reaction mixture. The solution was extracted with dichloromethane (3 x 20 mL),

washed with saturated Na2CO3 solution (25 mL), dried over Na2SO4, and concentrated by

rotary evaporation. The resulting residue was purified by column chromatography on silica

gel (CH2Cl2/n-hexane (2/3, v/v)) and dried at 50 °C/10–3 mbar to yield 78 mg (75 %) of 4 as a

highly viscous dark green oil.

S5

NN

N

N

O

O

O

O

4

C78H116N4O4 (1173.81)

1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 8.38–8.53 (m, 4H), 7.78 (d, 3J(H,H) = 8.2 Hz,

2H), 5.22 (sept, 2H), 3.78 (bs, 4H), 2.88 (bs, 4H), 2.22–2.32 (m, 4H), 1.93–2.15 (m, 8H),

1.77–1.86 (m, 4H), 1.15–1.38 (m, 72H), 0.84 (t, 3J(H,H) = 7.1 Hz, 12H). HRMS (ESI, pos.

mode, acetonitrile/CHCl3 1:1): m/z 1172.8994 [M]+ (calcd for C78H116N4O4 1172.8991).

UV/Vis (CH2Cl2): λmax/nm (ε/L mol–1 cm–1) 698 (40600), 433 (15900); fluorescence

(CH2Cl2): λmax = 736 nm (λex = 440 nm), Фfl = 0.16. Elemental analysis (%) calculated for

C78H116N4O4: C 79.81, H 9.96, N 4.77; found C 79.78, H 9.91, N 4.78.

N-1-Undecyldodecyl-1,7-dipyrrolidinylperylene-3,4:9,10-tetracarboxylic acid-

3,4-anhydride-9,10-imide (5)

N,N’-Di(1-undecyldodecyl)-1,7-dipyrrolidinylperylene-3,4:9,10-tetracarboxylic acid bisimide

(4; 373 mg, 318 μmol) and 40 mL tert-butanol were brought to reflux under a nitrogen

atmosphere. KOH (1.23 g, 21.9 mmol) was dissolved in 25 mL hot tert-butanol and given to

the reaction solution. After heating for 10 min, the hot mixture was carefully poured into a

mixture of 17 mL acetic acid and 14 mL 2 N HCl. The reaction mixture was cooled to room

temperature and extracted with dichloromethane (3 x 30 mL), washed with saturated Na2CO3

solution, dried over Na2SO4, and concentrated by rotary evaporation. The resulting green

residue was purified by column chromatography on silica gel (CH2Cl2/n-hexane/acetone

(12/8/1, v/v/v)). Afterwards the product was dissolved in a small amount of dichloromethane,

S6

and precipitated with methanol, and dried at 10–3 mbar to yield 248 mg (80 %) of 5 as a dark

green solid. Mp: 99–100 °C (from MeOH).

ON

N

N

O

O

O

O

5

C55H69N3O5 (852.17)

1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 8.41–8.55 (m, 4H), 7.79 (d, 3J(H,H) = 8.1 Hz,

1H), 7.61 (d, 3J(H,H) = 8.1 Hz, 1H), 5.21 (sept, 1H), 3.77 (bs, 4H), 2.88 (bs, 4H), 2.20–2.32

(m, 2H), 1.95–2.18 (m, 8H), 1.80–1.88 (m, 2H), 1.15–1.35 (m, 36H), 0.84 (t, 3J(H,H) =

7.2 Hz, 6H). HRMS (ESI, pos. mode, acetonitrile/CHCl3 1:1): m/z 851.5237 [M]+ (calcd for

C55H69N3O5 851.5232). UV/Vis (CH2Cl2): λmax/nm (ε/L mol–1 cm–1) = 704 (41100), 433

(16100); fluorescence (CH2Cl2): λmax = 746 nm (λex = 440 nm), Фfl = 0.10. Elemental analysis

(%) calculated for C55H69N3O5: C 77.52, H 8.16, N 4.93. Found: C 77.26, H 7.94, N 4.92.

1-[2-Methyl-6-nitro-1-benzo[b]thiophen-3-yl)-2-(2’-methyl-1’-benzo[b]thiophen-3’-yl)-

perfluorocyclopentene (6)

A solution of 1,2-bis-(2-methylbenzo[b]thiophen-3-yl)-perfluorocyclopentene (784 mg,

1.67 mmol) in 11 mL acetic acid and 1.1 mL acetic anhydride was cooled to below 15 °C and

0.1 mL (2.41 mmol) fuming nitric acid was slowly added to the solution, while the

temperature was kept below 15 °C. The mixture was stirred overnight at room temperature,

afterwards 20 mL cold water was added to it. The mixture was extracted with ethyl acetate

(3 x 10 mL), washed with water, dried over Na2SO4, and concentrated by rotary evaporation.

The residue was purified by column chromatography on silica gel (n-hexane/ethyl acetate

S7

(5/1, v/v)) and the product was dried at 10–3 mbar to yield 396 mg (46 %) of 6 as a white

solid. Mp: 170-171 °C (from n-hexane).

SS

FFFFF

F

NO2

6

C23H13F6NO2S2 (513.48)

The signals in 1H NMR spectra of 1o, 3o and 5 for the parallel and anti-parallel isomers are

indicated by “p” and “ap”, respectively, and signal integrals are normalized.

S

R

S

R

RSS

R

parallel anti-parallel 1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 8.64 (d, 4J(H,H) = 1.8 Hz, 0.7H, ap), 8.53 (s,

0.3H, p), 8.24 (dd, 3J(H,H) = 9.0 Hz, 4J(H,H) = 1.9 Hz, 0.7H, ap), 8.03 (dd, 3J(H,H) = 9.0 Hz,

4J(H,H) = 1.8 Hz, 0.3H, p), 7.47–7.76 (m, 3H, ap), 7.28–7.41 (m, 1.2H, ap), 7.18–7.24 (m,

0.8H, p), 2.57 (s, 1 H, p), 2.48 (s, 1H, p) , 2.31 (s, 2H, ap), 2.22 (s, 2H, ap). HRMS (APCI,

pos. mode, CHCl3): m/z 514.0360 [M+H]+ (calcd for C23H14F6NO2S2 514.0370). UV/Vis

(CH2Cl2): λmax/nm (ε/L mol–1 cm–1) = 300 (14200), 258 (17500).

Open form of 1,7-dipyrrolidinylperylene-diarylethene conjugate (1o)

To a methanolic solution (2 mL) of 6 (100 mg, 195 μmol), 52.2 mg (220 μmol) of

NiCl2·6H2O were added under stirring at 0 °C for 15 min. Afterwards 53.0 mg (1.40 mmol)

NaBH4 were added slowly and the mixture was stirred at room temperature for further 2 h.

Dichloromethane (20 mL) was given to the reaction mixture, washed with brine, dried over

Na2SO4, and concentrated by rotary evaporation. The resultant precipitate was purified by

column chromatography on silica gel (CH2Cl2/acetone (10/1, v/v)), dried at 10–3 mbar, to

yield 79.2 mg (84 %) of the reduced compound 1-[6-amino-2-methyl-1-benzo[b]thiophen-3-

S8

yl)-2-(2’-methyl-1’-benzo[b]thiophen-3’-yl)-perfluorocyclopentene (7) as pale yellow solid.

The unstable product was directly used for the further reaction.

SS

FFFFF

F

NH2

7

A mixture of 7 (39.3 mg, 81.5 μmol), 5 (82.5 mg, 96.8 μmol), and imidazole (750 mg) was

heated to 105 °C under a nitrogen atmosphere for 6.5 h. Ethanol (5 mL) was carefully poured

into the hot solution. The reaction mixture was cooled to room temperature and 20 mL

dichloromethane and 10 mL 2 N HCl were added to it. The solution was extracted with

dichloromethane (3 x 20 mL), dried over Na2SO4, and concentrated by rotary evaporation.

The residue was purified by column chromatography on silica gel (CH2Cl2 (v)) and dried at

10–3 mbar to yield 181 mg (71 %) of 1o as a dark green solid. Mp: 151 °C (from MeOH).

SS

FFFFF

F

N

N

N

N

O

O

O

O

1o

C78H82F6N4O4S2 (1317.63)

1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 8.38–8.57 (m, 4H), 7.58–7.85 (m, 6H.), 7.17–

7.41 (m, 3H.), 5.22 (sept, 1H), 3.78 (bs, 4H), 2.88 (bs, 4H), 2.54 (s, 0.8H, p), 2.51 (s, 0.8H, p),

2.28 (s, 2.2H, ap), 2.24 (s, 2.2H, ap), 2.21–2.31 (m, 2H), 1.93–2.17 (m, 8H), 1.80–1.91 (m,

2H), 1.15–1.35 (m, 36H), 0.85 (t, 3J(H,H) = 7.1 Hz, 6H). HRMS (ESI, pos. mode,

acetonitrile/CHCl3 1:1): m/z 1316.5676 [M]+ (calcd for C78H82F6N4O4S2 1316.5676). UV/Vis

(CH2Cl2): λmax/nm (ε/L mol–1 cm–1) = 704 (43000), 434 (16900), fluorescence (CH2Cl2): λmax =

745 nm (λex = 440 nm), Фfl = 0.14. Elemental analysis (%) calculated for C78H82F6N4O4S2

(1317.63): C 71.10, H 6.27, N 4.25, S 4.87; found C 70.73, H 6.09, N 4.30, S 4.30.

S9

Closed form of 1,7-dipyrrolidinylperylene-diarylethene conjugate (1c)

A solution of 1o (37.0 mg, 28.1 μmol) in 220 mL dichloromethane was irradiated in a

Rayonet photo reactor with UV light (λmax = 350 nm) for 20 min under vigorous stirring. The

solution was concentrated by rotary evaporation in the dark and the resultant precipitate was

purified in the dark by column chromatography on silica gel (n-hexane/acetone (4/1, v/v)) and

product was dried at 10–3 mbar to yield 16.3 mg (44 %) of 1c as a dark green solid.

FFFFF

F

S SN

N

N

N

O

O

O

O

1c

C78H82F6N4O4S2 (1317.63)

1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 8.38–8.56 (m, 4H), 8.08 (d, 3J(H,H) = 8.6 Hz,

1H.), 7.94 (d, 3J(H,H) = 8.2 Hz, 1H.), 7.82 (d, 3J(H,H) = 8.1 Hz, 1H.), 7.72 (d, 3J(H,H) =

8.1 Hz, 1H.), 7.24–7.34 (m, 3H.), 7.11–7.20 (m, 2H.), 5.22 (sept, 1H), 3.79 (bs, 4H), 2.89 (bs,

4H), 2.21–2.34 (m, 2H), 2.10 (s, 3H), 2.07 (s, 3H), 1.94–2.18 (m, 8H), 1.78–1.91 (m, 2H),

1.14–1.38 (m, 36H), 0.85 (t, 3J(H,H) = 7.1 Hz, 6H). HRMS (ESI, pos. mode,

acetonitrile/CHCl3 1:1): m/z 1317.5746 [M+H]+ (calcd for C78H83F6N4O4S2 1317.5754).

UV/Vis (CH2Cl2): λmax/nm (ε/L mol–1 cm–1) = 707 (46900), 518 (12400), 436 (20900),

fluorescence (CH2Cl2): λmax = 747 nm (λex = 440 nm), Фfl = 0.12.

Open form of reference compound with phthalic imide residue (3o)

A mixture of 7 (see synthesis of 1o) (16.1 mg, 33.3 μmol), phthalic anhydride (10.0 mg,

66.6 μmol), and imidazole (500 mg) was heated to 110 °C under nitrogen atmosphere for 6 h

and then, ethanol (10 mL) were carefully poured into the hot solution. The reaction mixture

was cooled to room temperature, and 20 mL dichloromethane and 10 mL 2 N HCl were

S10

added. The solution was extracted with dichloromethane (3 x 20 mL), dried over Na2SO4, and

concentrated by rotary evaporation. The residue was purified by column chromatography on

silica gel (n-hexane/ethyl acetate (3/1, v/v)), and dried at 10–3 mbar to yield 11.2 mg

(18.3 μmol, 55 %) of 3o as a white solid. Mp: 204–205 °C (from n-hexane).

FFFFF

F

SS N

O

O3o

C31H17F6NO2S2 (613.593)

1H NMR (400 MHz, CDCl3, TMS, 300 K): δ 7.91–7.99 (m, 2H), 7.53–7.83 (m, 6H), 7.45–

7.50 (m, 0.6H), 7.25–7.40 (m, 1.7H), 7.16–7.24 (m, 0.7H), 2.56 (s, 1H, p), 2.52 (s, 1H, p),

2.25 (s, 2H, ap), 2.23 (s, 2H, ap). HRMS (APCI, pos. mode, CHCl3): m/z 614.0683 [M+H]+

(calcd for C31H18F6NO2S2 614.0683). UV/Vis (CH2Cl2): λmax/nm (ε/L mol–1 cm–1) = 298

(10300), 265 (23300).

Closed form of reference compound with phthalic imide residue (3c)

A solution of 3o (54.7 mg, 89.1 μmol) in 200 mL dichloromethane was irradiated in a

Rayonet photo reactor with UV light (300 nm) for 10 min under vigorous stirring. The

solution was concentrated by rotary evaporation in the dark and the resultant precipitate was

purified in the dark by column chromatography on silica gel (n-hexane/dichloromethane (1/1,

v/v)), dried at 10–3 mbar to yield 12.8 mg (23 %) of 3c as a dark red solid.

FFFFF

F

SS N

O

O3c

C31H17F6NO2S2 (613.593)

S11

1H NMR (600 MHz, CDCl3, TMS): δ 8.02 (d, 3J(H,H) = 8.7 Hz, 1H), 7.91–8.01 (m, 2H), 7.93

(d, 3J(H,H) = 8.2 Hz, 1H), 7.81–7.85 (m, 2H), 7.42 (d, 4J(H,H) = 1.9 Hz, 1H), 7.30–7.34 (m,

2H), 7.26–7.29 (m, 1H), 2.05 (s, 3H), 2.04 (s, 3H). HRMS (APCI, pos. mode, CHCl3):

614.0684 [M+H]+ (calcd for C31H18F6NO2S2 614.0683). UV/Vis (CH2Cl2): λmax/nm

(ε/L mol–1 cm–1) = 530 (9700), 437 (3500), 367 (11800), 355 (12200), 295 (15700).

S12

3. Fluorescence Measurements

Table S1. Fluorescence quantum yields of 1o, 1c and 2 in different solvents.

Φfl (%)

solvent εr 1o 1c 2

tetrachloromethane 2.24 39 40 39

chloroform 4.89 18 17 17

ethyl acetate 6.02 16 11 15

THF 7.58 13 9 14

dichloromethane 8.93 14 12 15

acetone 20.56 11 3 10

DMF 36.71 8 < 1 9

S13

4. UV/Vis Absorption and Fluorescence Spectra

300 400 500 600 700 8000

10

20

30

40

50

60

ε / 103 M-1 cm-1

λ / nm

0.0

0.5

1.0

Ifl / a.u.

Figure S1. UV/Vis absorption (solid line; 10–5 mol/L) and fluorescence emission spectrum

(dotted line; λex = 440 nm) of 1o in dichloromethane.

300 400 500 600 700 8000

10

20

30

40

50

60

ε / 103 M-1 cm-1

λ / nm

Ifl / a.u.

0.0

0.5

1.0

Figure S2. UV/Vis absorption (solid line; 10–5 mol/L) and fluorescence emission spectrum

(dotted line; λex = 440 nm) of 1c in dichloromethane.

S14

300 400 500 600 7000

10

20

30

40

50

λ / nm

ε / 103 M-1 cm-1

Figure S3. UV/Vis absorption spectrum of 2 in dichloromethane (10–5 mol/L).

300 400 500 6000

5

10

15

20

25

λ / nm

ε / 103 M-1 cm-1

Figure S4. UV/Vis absorption spectra of 3o (solid line) and 3c (dotted line) in

dichloromethane (10–5 mol/L).

S15

5. Cyclic Voltammetry Studies

N,N’-Di(2,6-diisopropylphenyl)-1,7-dipyrrolidinylperylene-3,4:9,10-tetracarboxylic acid

bisimide (2)

-1500 -1000 -500 0 500E / mV vs. Fc / Fc+

1 μA

Figure S5. Cyclic voltammogram of reference dye 2 in CH2Cl2, concentration = 1.0 x 10–4 M.

Scan rate 100 mV s–1; supporting electrolyte TBAHFP (0.1 M).

Open form of reference DAE with phthalic imide residue (3o)

-2000 -1000 0 1000E / mV vs. Fc / Fc+

1 μA

Figure S6. Cyclic voltammogram of compound 3o in CH2Cl2, concentration = 2.2 x 10–4 M.

Scan rate 100 mV s–1; supporting electrolyte TBAHFP (0.1 M).

S16

Closed form of reference DAE with phthalic imide residue (3c)

-2000 -1000 0 1000E / mV vs. Fc / Fc+

1 μA

Figure S7. Cyclic voltammogram of compound 3c in CH2Cl2, concentration = 1.8 x 10–4 M.

Scan rate 100 mV s–1; supporting electrolyte TBAHFP (0.1 M).

Table S2. Redox potentials of compounds 1o, 1c, PBI 2, 3o and 3c (in V).

Ered (X3–/X2–)

Ered(X2–/X–)

Ered(X–/X)

Eox(X/X+)

Eox (X+/X2+)

Eox (X2+/X3+)

2 -- –1.49 –1.39 0.18 0.33 --

1o -- –1.48 –1.36 0.22 0.36 --

1c –1.60[a] –1.43 –1.31 0.21 0.35 1.00

3o -- -- –1.98[a] -- -- --

3c -- –1.90[a] –1.54[a] 0.95 -- --

[a] Peak potential

S17

6. Lifetime Measurements

Table S3. Lifetimes of 1o and 1c determined by emission and ultrafast absorption

spectroscopy.

solvent open form (τ / ns, emission)

closed form (τ / ns, emission)

closed form (τ / ps, trans. abs.)

DMF 2.1 ca. 0.29 242

DMSO 1.9 ca. 0.24 228

7. Femtosecond Transient Absorption Spectroscopy

500 600 700-0.15

-0.10

-0.05

0.00

ΔOD

λ / nm

1.5 ps 116 ps 546 ps 995 ps

Figure S8. Ultrafast transient absorption spectra in dimethyl sulfoxide of 1o; λex = 400 nm.

S18

8. Spectroelectrochemistry

Spectroelectrochemistry studies of reference dye 2 were carried out in dimethyl sulfoxide

(εr = 46.68) for proper comparison with the spectra from ultrafast transient absorption

spectroscopy. As shown in Figure S5 there is a good agreement with Figure 6: A maximum at

λmax = 609 nm that is attributed to the perylene bisimide radical cation and a bleach at

λmax = 713 nm for the neutral perylene bisimide. Notably, all maxima for the radical cation of

2 are shifted to longer wavelengths compared to those values published for similar

compounds in dichloromethane.[S6]

400 600 800 1000

-0.15

-0.10

-0.05

0.00

λ / nm

ΔOD

Figure S9. Differential spectrum of reference dye 2 (one-electron oxidized form) upon

oxidation in DMSO (0.5 x 10–3 M, 0.1 M Bu4NPF6).

S19

9. Excitation Spectrum

Figure S10. Excitation spectrum of 1o in dichloromethane (10–5 mol/L; detected at 735 nm).

300 400 500 600 7000.00

0.25

0.50

0.75

1.00

Ifl / a.u.

λ / nm

S20

10. Additional References

[S1] F. Würthner, V. Stepanenko, Z. Chen, C. R. Saha-Möller, N. Kocher, D. Stalke, J.

Org. Chem. 2004, 69, 7933–7939.

[S2] a) W. K. Anderson, E. J. LaVoie, J. C. Bottaro, J. Chem. Soc. PT 1 1976, 1–4; b) W.

H. Cherry, J. T. Craig, Q. N. Porter, Aust. J. Chem. 1979, 32, 133–143; c) M.

Hanazawa, R. Sumiya, Y. Horikawa, M. Irie, J. Chem. Soc., Chem. Commun. 1992,

206–207.

[S3] a) R. Gvishi, R. Reisfeld, Z. Burshstein, Chem. Phys. Lett. 1993, 213, 338–344; b)

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