Supporting Information for
Ground
and
Excited
State
Pinched
Cone
Equilibria
in
Calix[4]arenes Bearing Two Perylene Bisimide Dyes
Catharina Hippius†, Ivo H. M. van Stokkum¶, Ennio Zangrando#, René M. Williams*,‡,
Michael Wykes##, David Beljonne## and Frank Würthner*,†
Contribution from the †Universität Würzburg, Institut für Organische Chemie and Röntgen
Research Center for Complex Material Systems, Am Hubland, D-97074 Würzburg, Germany;
¶
Department of Physics and Astronomy, Vrije Universiteit, de Boelelaan 1081, 1081 HV
Amsterdam, The Netherlands;.
#
University of Trieste, Dipartimento di Scienze Chimiche, Via Licio Giorgieri 1, 34127
Trieste, Italy;
‡
Molecular Photonics Group, van’t Hoff Institute for Molecular Sciences (HIMS), Universiteit
van Amsterdam, Nieuwe Achtergracht 129, WS 1018 Amsterdam, The Netherlands;
##
Laboratory for Chemistry of Novel Materials, Center for Research in Molecular Electronics
and Photonics, University of Mons-Hainaut, Place du Parc 20, 7000 Mons , Belgium.
E-mail: wuerthner@chemie.uni-wuerzburg.de; williams@science.uva.nl
– S1 –
Materials and Methods.
Compounds oc,S1 rc,S2 gc,S3 oref and rref,S4 N-(1-pentyl-hexyl)-1,6,7,12-perylene-3,4:9,10tetracarboxylic
acid
imide
anhydride,S5
N-(butyl)-1,6,7,12-tetra(4-tert-butylphenoxy)-
perylene-3,4:9,10-tetracarboxylic acid imide anhydride,S6 N-(cyclohexyl)-1,7-bis(pyrrolidinyl)perylene-3,4:9,10-tetracarboxylic
acid
imide
anhydrideS7
and
5,17-Diamino-
25,26,27,28-tetrakis(propyloxy)-calix[4]areneS8 were synthesized according to literature
procedures. All compounds were characterized by 1H NMR spectroscopy, high resolution
mass spectrometry, and compounds o2c, g2c, and r2c additionally by elemental analysis.
Solvents were purified and dried according to standard procedures. Column chromatography
was performed with silica gel 60 (0.035–0.070 mm); PTLC on 20 x 20 cm plates, height 1
mm, silica gel 60 (0.035–0.070 mm). High performance liquid chromatography (HPLC) was
performed on SiO2 columns, normal phase (NP), with p.a. grade purified solvents. NMR
spectra were recorded on a 400 MHz and 600 MHz spectrometer. Mass Spectra were
performed on a Finnigan MAT MS 8200 or on a Bruker microTOFLC. For UV/vis absorption
and fluorescence experiments spectroscopy grade solvents were used.
UV/vis
absorption
spectra
were
taken
on
a
conventional
UV/vis
absorption
spectrophotometer.
Steady state fluorescence emission spectra were recorded on a PTI QM4-2003 fluorescence
spectrometer and are corrected against photomultiplier and lamp intensity. A long wavelength
range emission corrected photomultiplier R928 was used. Fluorescence quantum yields were
determined in CH2Cl2 vs. N,N’-(2,6-diisopropylphenyl)- 1,6,7,12-tetraphenoxyperylene3,4:9,10-tetracarboxylic acid bisimide (Φfl = 0.96 in CHCl3) or fluorescein (Φfl = 0.92 in 0.1N
NaOH) as reference.S9 The given quantum yields are averaged from values measured at three
different excitation wavelengths with OD 0.02–0.05 in the absorption maximum (standard
deviation σ = 1–3 %).
– S2 –
Fluorescence lifetimes were measured with a streak camera system (details described in the
literature).S10 As excitation source a Spectra-Physics Hurricane Titanium:Sapphire
regenerative amplifier system was used. The excitation wavelength of 530 nm (for all orange
and red compounds) and 640 nm (for all green compounds) was made with an optical
parametric amplifier (Spectra-Physics OPA 800). The excitation light was imaged onto the
cell with a mirror and the emission light was collected with a fiber coupled to the
spectrograph of the streak setup. To get the best temporal resolution at short times, the streak
camera was run in “dump mode”. In which, the sync signal from the hurricane setup is
combined with the trigger signal from a triggering diode to gain optimal resolution yielding a
system response of approximately 150 ps. Typical laser output was 5 mJ per pulse (130 fs
FWHM) with a repetition rate of 1 kHz. The samples were placed into 10 mm quartz cells and
were degassed for 15 minutes with argon gas prior to the measurements. Steady state
absorbance measurements were performed before and after the laser experiments to rule out
possible degradation of the sample.
Femtosecond transient absorption experiments were performed with a Spectra-Physics
Hurricane Titanium: Sapphire regenerative amplifier system.S11 The full spectrum setup was
based on an optical parametric amplifier (Spectra-Physics OPA 800) as the pump. The
residual fundamental light from the pump OPA was used for white light generation, which
was detected with a CCD spectrograph (Ocean Optics). The polarization of the pump light
was controlled by a Berek Polarization Compensator (New Focus). The Berek-Polarizer was
always included in the setup to provide the Magic-Angle conditions. The probe light was
passed over a delay line (Physik Instrumente, M-531DD) that provides an experimental time
window of 1.0 ns with a maximal resolution of 0.6 fs/step. The OPA was used to generate
excitation pulses at 530 nm (for all orange and red compounds) and at 640 nm (for all green
compounds). The laser output was typically 5 μJ pulse-1 (130 fs FWHM) with a repetition rate
of 1 kHz. The samples were placed into cells of 2 mm path length (Hellma) and were stirred
– S3 –
with a stir bar. Samples were prepared to have an optical density of ca. 0.3–0.6 at the
excitation wavelength and were degassed for 15 minutes with argon gas prior to the
measurements. The UV/vis absorption spectra of the samples were measured before and after
the laser experiments and were found to be virtually identical, thus possible degradation or
chemical change of the samples could be ruled out. All photophysical data reported here have
a 5 to 10% error limit, unless indicated otherwise. The experiments were performed at room
temperature. The power dependence was determined and it was found that the spectral and
kinetic behavior was independent of the laser power used. Four different laser powers were
applied by modulating the maximum laser power of the pump beam with a neutral density
filter wheel.
For the global and target analysis all time-gated spectra were collated in a matrix, which
was globally fitted using a sequential kinetic scheme with increasing lifetimes. From this the
lifetimes and the evolution-associated difference spectra (EADS) were estimated. The
instrument response function (IRF) is described by a Gaussian shape, and the white light
dispersion over the spectral range is modeled by a third order polynomial. With increasing
lifetimes, and thus decreasing rates, the first EADS decays with the first lifetime and
corresponds to the difference spectrum at time zero with an ideal infinitely small IRF. The
second EADS is formed with the first lifetime and decays with the second lifetime, etc. The
final EADS represents the difference spectrum of the longest living species. The error in the
lifetimes obtained from the fitting procedure does not exceed 10%. EADS may not represent
pure species, except for the final EADS, and they are interpreted as a weighted sum (with
only positive contributions) of species-associated difference spectra (SADS). The quality of
the fit was judged by inspection of the singular vectors of the matrix of residuals, which had
to be structure-less. Next, in target analysis a kinetic scheme was used in combination with
spectral assumptions to estimate microscopic rate constants and SADS. A full description of
the method has been given elsewhere.S12
– S4 –
Data collection for Crystal Structure determination were carried out at the X-ray diffraction
beam-line of the Elettra Synchrotron, Trieste (Italy), using the rotating crystal method with
the monochromatic wavelength of 1.000 Å. Data were collected on a CCD MAR detector.
Measurements were performed at 100 K using a nitrogen stream cryo-cooler. Cell refinement,
indexing and scaling of the data sets were carried out using Denzo and Scalepack.S13 The
structures was solved by direct methods using SHELXSS14 and refined by the full-matrix
least-squares method based on F2 with all observed reflections.S14 The hydrogen atoms were
placed at geometrically calculated positions. ΔF map of compound r2c revealed disordered
CHCl3 solvent accounting for 6 molecules for asymmetric unit. The propane chain at O4 and
a tert-butylphenoxy group were found disordered (two positions, 50% each). All the
calculations were performed using the WinGX System, Version 1.70.01.S15 Crystal data for
compound r2c: C176H176N4O20.6(CHCl3), M = 3383.42, triclinic; space group Pī, a =
16.634(4), b = 17.396(4), c = 33.549(5) Å, α = 92.05(3), β = 96.55(2), γ = 93.72(3)°, V =
9615(4) Å3, Z = 2, ρcalcd = 1.169 g/cm3, F(000) = 3536. Final R = 0.1234, wR2 = 0.3272, S =
1.193 for 2066 parameters and 95672 reflections, 18991 unique [R(int) = 0.0250], of which
15274 with I > 2σ(I). Crystal size was approximately of 0.5 mm. Full crystallographic data
have been deposited at the Cambridge Crystallographic Data Centre (CCDC reference number
687096).
Calix[4]arene Conformations
OH
HO HO OH OH
cone
C4V
OH
OH
OH
HO HO OH
HO
partial cone
CS
1,2-alternate
C2h
OH
OH
OHOH
1,3-alternate
D2d
Figure S1. The four basic conformations of calix[4]arene and related symmetry classes.
– S5 –
Synthesis and Chemical Characterization.
Compound o2c
A suspension of 100 mg (1.61 x 10-4 mol, 1 equiv.) of 5,17-Diamino-25,26,27,28tetrakis(propyloxy)-calix[4]arene, 351 mg (6.43 x 10-4 mol, 4 equiv.) of N-(1-pentyl-hexyl)1,6,7,12-perylene-3,4:9,10-tetracarboxylic acid imide anhydride and 118 mg (6.43 x 10-4 mol,
4 equiv.) of Zn(OAc)2 (H2O-free) was heated in 2 mL distilled quinoline at 165 °C for 14 h
under an argon atmosphere. The cooled reaction mixture was poured into 2N HCl and stirred
for 30 minutes at 40 °C. To the solution 50 mL of CH2Cl2 were added and the resulting
organic phase was washed with water and brine and dried over MgSO4. The crude product
was purified by column chromatography with CH2Cl2 and CH2Cl2/ethyl acetate 97:3 and
successively by precipitation from CH2Cl2/methanol. Compound o2c was obtained as a lightred powder (146 mg, 8.70 x 10-5 mol, yield 55%). C110H108N4O12 (1678.05). Mp = 319–326
°C. TLC CH2Cl2; Rf = 0.01. 1H NMR (400 MHz, CDCl3, 25 °C): δ (ppm) = 8.76 (bd, 4H, 3J =
7.7 Hz; Per-H); 8.66 – 8.61 (m, 12H; Per-H); 7.12 (s, 4H; Ar-H); 6.46 (t, 2H, 3J = 7.5 Hz; ArH); 6.33 (bd, 4H, 3J = 7.0 Hz; Ar-H); 5.21 – 5.17 (m, 2H, N-CH); 4.55 and 3.22 (AX, each
4H, 2J = 13.4 and 13.8 Hz; Ar-CH2-Ar); 4.14 (bt, 4H, 3J = 8.2; O-CH2); 3.71 (t, 4H, 3J = 6.6
Hz; O-CH2); 2.30 – 2.21 (m, 4H; Alkyl-H); 2.07 – 2.01 (m, 4H; Alkyl-H); 1.92 – 1.85 (m, 8H,
Propyl-H), 1.39 – 1.18 (m, 24H, Alkyl-H), 1.12 (t, 6H, 3J = 7.5 Hz; Alkyl-H); 0.95 (t, 6H, 3J =
7.5 Hz; Alkyl-H); 0.89 – 0.82 (m, 12H; Alkyl-H). HR-MS (ESI in CHCl3/acetonitrile): calcd
for C110H108N4NaO12 (m/z) 1699.7861 [M+Na]+; found 1699.7856. Analysis: calcd (%) for
C110H108N4O12 x H2O (1696.07): C 77.90; H 6.54; N 3.30; found: C 77.95; H 6.68; N 3.24.
UV/vis (CH2Cl2): λ (nm) [ε (M-1cm-1)] = 526 [164200], 490 [106700]. Fluorescence
(CH2Cl2): λmax (nm) = 536, 577; ΦFl = 0.03.
– S6 –
Compound r2c
Under an argon atmosphere 40 mg (6.42 x 10-5 mol, 1 equiv.) of 5,17-Diamino-25,26,27,28tetrakis(propyloxy)-calix[4]arene, 167 mg (1.61 x 10-4 mol, 2.5 equiv.) of N-(butyl)-1,6,7,12tetra(4-tert-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid imide anhydride and 5-6
drops of triethylamine in toluene (1.0 mL) were heated to 125 °C for 24 h. The solvent was
evaporated, the remaining crude product precipitated from CH2Cl2/methanol and the resulting
solid purified by column chromatography with CH2Cl2/hexane 75:25 and successively
precipitated from CH2Cl2/methanol. Compound r2c was obtained as a dark-red powder (140
mg, 5.25 x 10-5 mol, yield 82%). C176H176N4O20 (2667.30). Mp = 322–324°C. TLC
CH2Cl2/hexane 80:20; Rf = 0.81. 1H NMR (400 MHz, CDCl3, 25 °C): δ (ppm) = 8.28 and
8.24 (bs and s, 8H; Per-H); 7.25 – 7.21 (m, 16H; Phen-H); 7.00 (s, 4H; Ar-H); 6.87 – 6.83
(AX, 16H; Phen-H); 6.29 – 6.24 (m, 2H; Ar-H); 6.09 (d, 4H, 3J = 7.7 Hz; Ar-H); 4.43 and
3.10 (AX, 8H, 2J = 13.6 Hz; Ar-CH2-Ar); 4.12 and 4.05 (t and m, 8H, 3J = 7.5 Hz; O-CH2);
3.60 (t, 4H, 3J = 6.6 Hz; N-CH2); 1.94 – 1.78 (m, 8H; Propyl-H); 1.70 – 1.63 (m, 4H, ButylH); 1.45 – 1.36 (m, 4H, Butyl-H); 1.29 and 1.27 (each s, 72H, tert-Butyl-Phen-H); 1.06 (t,
6H, 3J = 7.4 Hz; Propyl-H); 0.94 (t, 6H, 3J = 7.3 Hz; Butyl-H); 0.83 (t, 6H, 3J =7.5 Hz;
Propyl-H). HR-MS (ESI in CHCl3/acetonitrile): calcd for C176H180N5O20 (m/z) 2683.3220
[M+NH4]+; found 2683.3216. Analysis: calcd (%) for C176H176N4O20 x H2O (2685.31): C
78.72; H 6.68; N 2.09; found: C 78.55; H 7.00; N 1.93. UV/vis (CH2Cl2): λ (nm) [ε (M-1cm-1)]
= 580 [92200]. Fluorescence (CH2Cl2): λmax (nm) = 612; ΦFl = 0.79.
Compound g2c
A suspension of 100 mg (1.38 x 10-4 mol, 1 equiv.) of 5,17-Diamino-25,26,27,28tetrakis(propyloxy)-calix[4]arene, 169 mg (2.76 x 10-4 mol, 2 equiv.) N-(cyclohexyl)-1,7bis(pyrrolidinyl)perylene-3,4:9,10-tetracarboxylic acid imide anhydride and 51 mg (2.76 x 104
mol, 2 equiv.) of Zn(OAc)2 (H2O-free) was heated in 1.5 mL distilled quinoline at 130 °C
– S7 –
for 20 h under an argon atmosphere. The cooled reaction mixture was poured into 40 mL 2N
HCl and stirred for 40 minutes at 50 °C. The resulting precipitate was filtered and dissolved in
CH2Cl2. The solution was washed with water and brine and dried over MgSO4. The crude
product was purified by column chromatography with CH2Cl2 and successively by
precipitation from CH2Cl2/hexane. Compound g2c was obtained as a dark-green powder (81
mg, 4.48 x 10-5 mol, yield 32%). C116H112N8O12 (1810.18). Mp = 351 °C (decomposition).
TLC CH2Cl2/ethyl acetate 98:2; Rf = 0.20. 1H NMR (400 MHz, CDCl3, 25 °C): δ (ppm) =
8.61 (bs, 2H; Per-H); 8.52 and 8.49 (d and s, 4H; Per-H); 8.39 (d, 2H, 3J = 7.7 Hz; Per-H);
7.76 – 7.73 (m, 4H; Per-H); 7.14 (s, 4H; Ar-H); 6.44 (t, 2H, 3J = 7.5 Hz; Ar-H); 6.29 (d, 4H,
3
J = 7.5 Hz; Ar-H); 5.11 – 5.06 (m, 2H; Cy-H); 4.54 and 3.21 (AX, 8H, 2J = 13.5 and 13.7 Hz;
Ar-CH2-Ar); 4.17 – 4.13 (m, 4H; O-CH2); 3.78 and 3.68 (bs and t, 12H, 3J = 6.5 Hz; Pyrr-H
and O-CH2); 2.88 (bs, 8H; Pyrr-H); 2.66 – 2.57 (m, 4H; Cy-H); 2.09 – 1.74 (m, 34H; Pyrr-H,
Propyl-H, Cy-H); 1.50 – 1.34 (m, 6H; Cy-H); 1.13 (t, 6H, 3J = 7.4 Hz; Propyl-H); 0.93 (t, 6H,
3
J = 7.5 Hz; Propyl-H). HR-MS (ESI in CHCl3): calcd. for C116H112N8O12 (m/z) 904.4199
[M]2+; found 904.4194. Analysis: calcd (%) for C116H112N8O12 (1810.18): C 76.97; H 6.24; N
6.19; found C 77.28; H 6.87; N 5.85. UV/vis (CH2Cl2): λ (nm) [ε (M-1cm-1)] = 706 [92400].
Fluorescence (CH2Cl2): λmax (nm) = 744; ΦFl = 0.22.
Compound gref
A solution of 60 mg (6.91 x 10-5 mol, 1 equiv.) of isomerically pure 1,7-dibromo-N,N’-2,6diisopropylphenyl-perylene-3,4:9,10-tetracarboxylic acid bisimideS16 in 3.5 mL pyrrolidin (42
mmol, 608 equiv.) was heated at 50 °C for 17 h under an argon atmosphere. The cooled
reaction mixture was poured into 40 mL 1N HCl and was stirred for 90 minutes at 50 °C. To
the solution 50 mL of CH2Cl2 were added and the resulting organic phase was washed with
water and brine and dried over Na2SO4. The crude product was purified by column
chromatography with CH2Cl2 and successively by HPLC with CHCl3/acetone/hexane 12:1.5:9
– S8 –
(SiO2, normal phase) and by precipitation from CH2Cl2/methanol. Compound gref was
obtained as a dark green powder (10 mg, 1.18 x 10-5 mol, yield 17%). C56H56N4O4 (849.07).
Mp = 286 °C (decomp.). TLC CHCl3/Aceton/Hexan 12:1.5:9; Rf = 0.65. 1H NMR (400 MHz,
CDCl3, 25 °C): δ (ppm) = 8.58 (s, 2H; Per-H); 8.51 (d, 2H, 3J = 8.0 Hz; Per-H); 7.79 (d, 2H,
3
J = 8.1 Hz; Per-H); 7.49 (t, 2H, 3J = 7.7 Hz; Ar-H); 7.34 (d, 4H, 3J = 7.7 Hz; Ar-H); 3.83 (bs,
4H, 3J = 6.8 Hz; Pyrr-H); 2.93 and 2.83 – 2.76 (bs and m, 8H; Pyrr-H and i-Propyl-H); 2.10
and 2.03 (each bs, 8H; Pyrr-H); 1.18 (dd, 24H, 3J = 6.8 Hz and 4J = 1.5 Hz; i-Propyl-H). HRMS (ESI in CHCl3/acetonitrile): calcd C56H56N4O4 (m/z) 848.4302 [M]+; found 848.4296.
UV/vis (CH2Cl2): λ (nm) [ε (M-1cm-1)] = 709 [43000]. Fluorescence (CH2Cl2): λmax (nm) =
748; ΦFl = 0.19.
1
H NMR Spectra
Figure S2. 1H NMR spectrum (400 MHz, CDCl3, room temperature) of compound o2c.
– S9 –
Figure S3. 1H NMR spectrum (400 MHz, CDCl3, room temperature) of compound r2c.
Figure S4. 1H NMR spectrum (400 MHz, CDCl3, room temperature) of compound g2c.
– S10 –
Crystal Structure
The crystal packing reveals a pair of molecules that is related by an inversion center in such a
way that intermolecular π−π stacking of the aromatic perylene systems is enabled at a mean
distance of about 4.0 Å (see Figure S4). Accordingly, no intramolecular π−π interaction has
been found within the red dimer system r2c in the solid state. The unit cell has 32.0% of void
volume accessible for solvent and a total of six disordered molecules of CHCl3 were found in
the asymmetric unit cell. The dihedral angles formed by the calix[4]arene C26/C28 and
C25/C27 phenyl rings are 2.6(5)° and 75.4(2)°, and correspondingly the C26-C28 and C25C27 distances are 5.22(1) and 9.86(1) Å, respectively (for C labels, see Figure 2 in the main
manuscript). The dihedral angles between the calix[4]arene phenyl rings and a “reference
plane” passing through the four CH2-methylene bridges of the calix[4]arene are 39.0(2)° for
the phenyl ring containing the carbon atom C25 atom, 87.3(2), 36.4(2), and 89.9(2)° for the
phenyl unit containing the carbon atoms C26, C27, and C28, respectively. The torsion angles
around the N1-C25 and N3-C27 bonds are -72.2(8)° (C(17)-C(25)-N(1)-C(34)), 109.4(8)°
(C(17)-C(25)-N(1)-C(30)), 105.8(8)° (C(18)-C(25)-N(1)-C(34)), and -72.6(8) (C(18)-C(25)N(1)-C(30)) for the N1-C25 bond; and the correspondent values about the N3-C27 bond are
68.7(9), -104.3(8), -108.9(8), and 78.1(8)°.
Figure S5. View of the crystal packing of pair of molecules related by a center of symmetry.
– S11 –
Figure S6. View of perylene units along the N-N axis showing the twisted backbone.
– S12 –
1
H NMR Spectra in CCl4.
o2c
oc
4.7
4.6
4.5
CCl4
CCl4
CDCl3
CDCl3
3.4
3.3
3.2
3.1
3.0
4.8
4.7
4.6
4.5
4.4
3.2
3.1
3.0
3.3
3.2
3.1
3.0
2.9
2.8
g2c
gc
CCl4
CCl4
CDCl3
4.6
4.5
4.4
3.3
CDCl3
3.2
3.1
3.0
4.8
4.7
4.6
4.5
4.4
3.4
δ / ppm
δ / ppm
r2c
rc
CCl4
CCl4
CDCl3
4.6
3.3
δ / ppm
δ / ppm
4.7
3.4
4.5
4.4
3.2
CDCl3
3.1
3.0
4.6
4.5
4.4
4.3
3.2
3.1
3.0
δ / ppm
δ / ppm
Figure S7. Sections of 1H NMR spectra (600 MHz) showing the Ar-CH2-Ar protons of the respective
calix[4]arene moiety in CCl4 (top line) and CDCl3 (bottom line) as indicated above in the individual spectra.
Top: compound oc (left) and compound o2c (right). Middle: compound gc (left) and compound g2c (right).
Bottom: compound rc (left) and compound r2c (right). Spectra of compounds oc and o2c are repeated for
comparison from Figure 3.
– S13 –
o2c
oc
CCl4
CCl4
CDCl3
9.0
8.8
8.6
8.4
CDCl3
9.0
8.2
8.5
8.0
δ / ppm
δ / ppm
g2c
gc
CCl4
CCl4
CDCl3
CDCl3
8.7
8.6
8.5
8.8
8.4
8.7
8.6
8.5
8.3
8.2
8.1
8.0
δ / ppm
δ / ppm
r2c
rc
8.5
8.4
CCl4
CCl4
CDCl3
CDCl3
8.4
8.3
8.2
8.1
8.6
8.5
8.4
8.3
8.2
8.1
8.0
δ / ppm
δ / ppm
Figure S8. Sections of 1H NMR spectra (600 MHz) showing the signals of the protons in the bay area of the
respective PBI moiety in CCl4 (top line) and CDCl3 (bottom line) as indicated above in the individual spectra.
Top: compound oc (left) and compound o2c (right). Middle: compound gc (left) and compound g2c (right).
Bottom: compound rc (left) and compound r2c (right).
– S14 –
Variable Temperature 1H NMR Spectra in CCl4.
o2c
g2c
334 K
293 K
273 K
4.5
4.4
3.4
305 K
305 K
293 K
305 K
4.6
315 K
315 K
315 K
4.7
325 K
325 K
325 K
4.8
r2c
334 K
3.3
3.2
3.1
3.0
4.7
4.6
4.5
δ / ppm
293 K
283 K
283 K
273 K
273 K
4.4
3.4
3.3
3.2
3.1
3.0 4.6
4.5
4.4
δ / ppm
4.3
3.2
3.1
3.0
2.9
2.8
δ / ppm
Figure S9. Sections of variable temperature 1H NMR spectra (600 MHz, in CCl4) of compound o2c (left), g2c
(middle), and r2c (right) showing the Ar-CH2-Ar protons of the respective calix[4]arene moiety. Temperatures
are indicated above in the individual spectra. Notably, in the spectra at lower temperatures of compound r2c two
smaller doublets are observed additionally to the signals present in CDCl3, which vanish upon heating the sample
at around 315 K. Similar line broadening effects have also been observed also for the signals of the bay protons
of the PBI moiety (see also Figure S10 below).
o2c
334 K
r2c
g2c
325 K
8.8
8.7
8.6
δ / ppm
8.5
8.4
8.3
8.2
305 K
293 K
293 K
283 K
273 K
273 K
8.9
315 K
305 K
305 K
293 K
9.0
325 K
325 K
315 K
315 K
9.1
334 K
8.8
8.7
8.6
8.5
8.4
8.3
δ / ppm
8.2
8.1
8.0
283 K
273 K
8.4
8.3
8.2
8.1
8.0
δ / ppm
Figure S10. Sections of variable temperature 1H NMR spectra (600 MHz, in CCl4) of compounds o2c (left), g2c
(middle), and r2c (right) showing the signals of the protons in the bay area of the respective PBI moiety.
Temperatures are indicated above in the individual spectra.
– S15 –
UV/vis Absorption Spectra
1.75
1.50
1.25
PhCN
CH2Cl2
1.00
Toluene
CCl4
0.75
o2c
1.25
Δ A / a. u.
1.50
Δ A / a. u.
1.75
oc
MCH
0.50
0.25
PhCN
CH2Cl2
1.00
Toluene
CCl4
0.75
MCH
0.50
0.25
0.00
350
400
450
500
550
0.00
350
600
400
450
1.0
0.8
0.6
Toluene
CCl4
Δ A / a. u.
Δ A / a. u.
gc
PhCN
CH2Cl2
MCH
0.4
0.2
g2c
0.8
PhCN
CH2Cl2
0.6
Toluene
CCl4
MCH
0.4
0.0
400
500
600
700
400
800
500
rc
Δ A / a. u.
Δ A / a. u.
1.0
PhCN
CH2Cl2
0.8
Toluene
CCl4
0.6
600
700
800
λ / nm
λ / nm
MCH
0.4
r2c
0.8
PhCN
CH2Cl2
0.6
Toluene
CCl4
MCH
0.4
0.2
0.2
0.0
350
600
0.2
0.0
1.0
550
λ / nm
λ / nm
1.0
500
400
450
500
550
600
0.0
350
650
400
450
500
550
600
650
λ / nm
λ / nm
Figure S11. Normalized UV/vis absorption spectra in benzonitrile (PhCN, black line), CH2Cl2 (red line), toluene
(green line), CCl4 (blue line) and methylcyclohexane (MCH, cyan line). Top: compound oc (left) and compound
o2c (right). Middle: compound gc (left) and compound g2c (right). Bottom: compound rc (left) and compound
r2c (right). Spectra of compounds o2c and g2c are repeated for comparison from Figure 4.
– S16 –
Temperature-Dependent UV/vis Absorption Spectra.
100
-1
20°C
70°C
3
60
60
ε / 10 M cm
3
-1
ε / 10 M cm
-1
80
80
-1
oc
100
40
20
0
350
400
450
500
550
o2c
20°C
70°C
40
20
0
350
600
400
450
λ / nm
50
70
600
10
50
-1
20
g2c
60
40
3
ε / 10 M cm
-1
20°C
70°C
-1
ε / 10 M cm
-1
40
3
550
80
gc
30
500
λ / nm
30
20°C
70°C
20
10
0
350
400
450
500
550
600
650
700
750
0
350
800
400
450
500
λ / nm
750
800
r2c
-1
ε / 10 M cm
20°C
70°C
30
3
20
10
400
450
20°C
70°C
60
-1
-1
700
80
3
-1
ε / 10 M cm
650
100
rc
40
0
350
600
λ / nm
60
50
550
500
550
600
650
λ / nm
40
20
0
350
400
450
500
550
600
650
λ / nm
Figure S12. UV/vis absorption spectra of variable temperatures in CCl4. Top: compounds oc (left, c = 4.56 x 106
M) and o2c (right, c = 5.83 x 10-6 M). Middle: compounds gc (left, c = 5.09 x 10-6 M) and g2c (right, c = 5.84
x 10-6 M). Bottom: compounds rc (left, c = 5.09 x 10-6 M) and r2c (right, c = 4.70 x 10-6 M). Concentrations
given at 20 °C. Arrows indicate trends upon rising temperature. Spectra are corrected for density changes due to
rising temperature. Spectra of compounds oc and o2c are repeated for comparison from Figure 5.
– S17 –
50
40
20°C
70°C
30
3
60
-1
80
-1
oref
ε / 10 M cm
3
-1
ε / 10 M cm
-1
100
40
20
0
350
gref
20°C
70°C
20
10
0
400
450
500
550
400
600
500
600
700
800
λ / nm
λ / nm
60
40
rref
20°C
70°C
30
3
-1
ε / 10 M cm
-1
50
20
10
0
350
400
450
500
550
600
650
λ / nm
Figure S13. UV/vis absorption spectra of variable temperatures in CCl4. Top left: compound oref (c = 4.96 x
10-6 M). Top right: compound gref (c = 3.83 x 10-6 M). Bottom: compound rref (c = 4.89 x 10-6 M).
Concentrations are given at 20°C. Arrows indicate trends upon rising temperature. Spectra are corrected for
density changes due to rising temperature.
– S18 –
Steady State Fluorescence Emission Spectra.
1.2
1.4
oc
I / a. u.
1.0
MCH
0.6
0.2
0.2
550
600
650
700
750
800
MCH
0.6
0.4
500
Toluene
CCl4
0.8
0.4
0.0
450
PhCN
CH2Cl2
1.0
Toluene
CCl4
0.8
o2c
1.2
PhCN
CH2Cl2
Ι / a.u.
1.4
0.0
450
850
500
550
λ / nm
1.0
0.8
Toluene
CCl4
0.8
0.6
MCH
I / a.u.
I / a. u.
gc
PhCN
CH2Cl2
1.0
0.4
0.2
650
700
750
rc
800
850
750
800
850
PhCN
CH2Cl2
Toluene
CCl4
0.6
MCH
0.4
0.0
600
900
650
1.0
750
800
r2c
850
900
PhCN
CH2Cl2
0.8
Ι / a.u.
Toluene
CCl4
0.6
700
λ / nm
PhCN
CH2Cl2
0.8
I / a. u.
700
g2c
λ / nm
MCH
0.4
Toluene
CCl4
0.6
MCH
0.4
0.2
0.2
0.0
500
650
0.2
0.0
600
1.0
600
λ / nm
550
600
650
700
750
800
0.0
500
850
550
600
650
700
750
800
850
λ / nm
λ / nm
Figure S14. Normalized steady state fluorescence emission spectra in benzonitrile (PhCN, black line), CH2Cl2
(red line), toluene (green line), CCl4 (blue line) and methylcyclohexane (MCH, cyan line) under dilute
conditions (OD of the respective solution < 0.05). Top: compound oc (left) and compound o2c (right). Middle:
compound gc (left) and compound g2c (right). Bottom: compound rc (left) and compound r2c (right). Spectra of
compounds oc and o2c are repeated for comparison from Figure 6.
– S19 –
Molecular Modeling.
Molecular modeling studies were conducted at the force-field level using the Amber 9
packageS17 and the Generalised Amber Force Field (GAFF)S18 parameters with partial charges
derived using the AM1-BCCS19 method implemented in the Amber 9 program Antechamber.
The charges were based on the π−stacked crossed configuration of each molecule optimized
at the AM1 semi-empirical level.
Molecular mechanics enthalpies of the solvated systems were dominated by solvent-solvent
interactions making the calculation of relative enthalpy of π−stacked and non π−stacked
conformations very imprecise. What more, any differences in entropy between π−stacked and
non π−stacked conformations should also be considered and hence relative free energies were
sought. Due to the difficulty of obtaining enthalpic and entropic contributions to the free
energy separately, relative free energies were calculated from probability distributions
extracted from molecular dynamics simulations. The Weighted Histogram Analysis Method
(WHAM)S20, an extension of the Umbrella Sampling technique provides the potential of mean
force (PMF) or the change in free energy along a reaction coordinate. The incremental
changes in free energy between neighboring points along the reaction coordinate are derived
from the ratio of their probabilities. Restraints known as Umbrella Potentials are commonly
employed to ensure sufficient sampling of unfavorable regions of the potential energy surface.
To calculate the relative free energies of π−stacked and non π−stacked conformations of the
dimers studied in this work, the reaction coordinate between π−stacked and non π−stacked
conformations was approximated as the distance between the centers of mass of the PBI units.
This choice of reaction coordinate was validated by Nudged Elastic BandS21 calculations in
AMBER 9 which showed that the inter-chromophoric distance decreased almost linearly
along the lowest enthalpy path between the open and closed forms. To ensure sufficient
sampling over unfavorable ranges of the reaction coordinate a series of MD simulations were
– S20 –
performed each with an Umbrella Potential which forced sampling over a different range of
the reaction coordinate. The WHAM was then applied to the histograms removing the biasing
effects of the Umbrella Potential to give the unbiased probability and relative free energy as a
function of the reaction coordinate.
Acetonitrile has a relative static permittivity (εr) of 37 at 300K, somewhat higher than the
most polar solvent, PhCN (εr=26 at 300K) used to obtain UV/vis absorption spectra. The
limiting case of a non-polar environment was represented by vacuum, with a relative static
permittivity of 1 by definition, lower than the least polar organic solvent, methyl cyclohexane
(εr=2 at 300K) used to obtain UV/vis absorption spectra.
Molecular dynamics (MD) simulations were performed at 300 K using the Langevin
dynamics thermostat and bonds involving hydrogen were constrained using the SHAKE
algorithm to enable the use of a 2 fs time step to increase the amount of sampling that could
be performed in a given amount of processing time. A non-bonded cut-off of 10 Angstroms
was used throughout. MD simulations were performed in explicit acetonitrile solution using
the acetonitrile model of Grabuleda et al.S20 whose density, heat of vaporization, and
isothermal compressibility values compare well to experimental data. These simulations were
performed under a constant pressure of 1 Atmosphere. The molecules o2c and r2c were each
placed in a truncated octahedron boxes (which typically gives a more uniform distribution of
solvent around the solute) of approximately 500 solvent molecules and MD calculations were
performed for 300 ps after which point equilibration was deemed complete as judged by the
convergence of density, temperature and energy.
Umbrella sampling was then performed using harmonic umbrella potentials E(x)=½ k(x-x0)2
with a spring constant k of 2.0 Kcal/molÅ2. Starting in a non-stacked configuration at an
interchromophoric distance of 15 Å, the chromophores were gradually brought together in a
series of sampling windows each with their umbrella potential centred at a consequently lower
distance in steps of 0.5 Å. Each window was sampled for 300 ps and the final geometry and
– S21 –
velocities were used to start the next window so that the system would follow an equilibrated
path. Sampling was also performed in the same way to sample the upper range of the reaction
coordinate between 15 and 25 Å. Distance measurements were performed every 20 fs and the
first 10 ps of distance measurements of each window were discarded to allow the system to
equilibrate.
The Weighted Histogram Analysis Method (WHAM)S21 was applied to combine the Umbrella
sampling windows into a single potential of mean force (PMF). An increasing number of bins
and finer convergence tolerances were used until the resulting PMFs were almost identical
indicating that no significant smoothening of the PMF was occurring due to an insufficient
number of bins and that the calculations had converged. The resulting PMFs can be found in
the main paper while structures found in the free energy wells can are shown in Figure S15
below. Each structure was obtained by averaging the coordinates of multiple MD snapshots
and optimizing the structure to take it to the nearest minima. The images in Figure S15,
bottom, reveal that for the dimeric compounds the inward-oriented PBI substituents are
twisted relative to the calix[4]arene core to reach an optimal π−π-stacking of the spacious
aromatic systems.
INDO/SCIS22 calculations were performed on the basis of the force field structures averaged
over the MD runs as described above. The configuration interaction space was built from all
possible single excitations involving the highest sixty occupied and lowest sixty unoccupied
molecular orbitals. The resulting lowest optical transitions were characterized via an analysis
of the atomic transition density distribution (providing a local mapping of the transition dipole
moment) and the electron-hole wavefunctions (allowing quantifying the on-chromophore vs.
charge-transfer contributions).S23,S24
– S22 –
Figure S15. Molecular structures obtained from force field calculations (Amber 9S17, potential GAFFS18 with
AM1-BCC partial chargesS19) of the non-stacked (top left), π−stacked parallel (top middle) and π−stacked
crossed (top right) pinched cone conformation of compounds o2c. Non-stacked (middle left), partially π−stacked
(middle right), π−stacked parallel (bottom left) and π−stacked crossed (bottom right) of r2c are also shown.
Color of the respective PBI chromophores is applied for clarity.
– S23 –
Time-Resolved Emission Spectroscopy.
The fluorescence lifetimes of all compounds have been determined and the respective data are
summarized in Table 3 in the main manuscript. For the green reference compound gref a
fluorescence lifetime of 2.5 ns is found in the most polar solvent benzonitrile. With
decreasing solvent polarity this value continuously increases up to 5.9 ns in MCH. The
fluorescence lifetimes of both the green calix[4]arene substituted compounds gc and g2c,
respectively, closely relate to those obtained for the reference compound gref: fluorescence
lifetime values of 2.7 – 2.8 ns are found for compounds gc and g2c in benzonitrile which
continuously increase for less polar solvents and reach a maximum value in MCH with 6.1 ns
for compound gc (for data refer to Table 3).
Likewise, for the red reference compound rref fluorescence lifetime values between 6.1 ns
and 6.9 ns are found in benzonitrile, CH2Cl2, toluene, CCl4, and in MCH. The fluorescence
lifetimes of both the red calix[4]arene substituted compounds rc and r2c, respectively, show
values that are in good agreement with those obtained for the red reference compound rref
and accordingly fluorescence lifetimes between 4.7 ns and 7.4 ns were determined in
benzonitrile, CH2Cl2, toluene, CCl4, and in MCH (see Table 3).
– S24 –
Femtosecond transient absorption data of compound o2c
o2c (CCl4)
0
-20
0
-20
-40
-80x10
500
λ / nm
700
-40
-80x10
500
600
700
λ / nm
-3
500
800
600
λ / nm
700
800
-0.05
o2c (PhCN)
-0.06
0
-20
-40x10
-3
800
Δ A / a. u.
Δ A / a. u.
20
600
0
-20
-60
-60
-3
o2c (DCM)
20
Δ A / a. u.
20
-40x10
o2c (Tol)
20
Δ A / a. u.
Δ A / a. u.
40
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
-0.07
-0.08
-0.09
-0.10
-3
-0.11
500
600
λ / nm
700
600
800
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
650
700
750
λ / nm
800
Figure S16. Femtosecond transient absorption spectra and corresponding time delays of compound o2c in
various solvents after photoexcitation at 530 nm. Top Left: in CCl4. Top Middle: in toluene (Tol). Top Right:
in CH2Cl2 (DCM). Bottom Left: in benzonitrile (PhCN). Note, that compound o2c in MCH was not measured as
the compound precipitates from solution after approximately 30 minutes. The scattered laser pulse is observed
for all measurements. Spectra of compounds o2c in CCl4 are repeated for comparison from Figure 10.
Femtosecond transient absorption data of compound oc
10
0.00
oc (Tol)
60
40
0
Δ A / a. u.
oc (CCl4)
ΔA / a. u.
Δ A / a. u.
0.05
-10
-20
-0.05
-30x10
-3
ΔA / a. u.
20
500
600
λ / nm
700
500
800
-40
600
λ / nm
700
800
-3
500
600
λ / nm
700
800
-0.05
oc (PhCN)
-0.06
0
-20
-40
-60x10
0
-20
-80x10
Δ A / a. u.
40
20
-60
-0.10
400
oc (DCM)
-0.07
-0.08
-0.09
-0.10
-3
-0.11
500
600
λ / nm
700
800
600
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S17. Femtosecond transient absorption spectra and corresponding time delays of compound oc in various
solvents after photoexcitation at 530 nm. Top Left: in CCl4. Top Middle: in toluene (Tol). Top Right: in
CH2Cl2 (DCM). Bottom Left: in benzonitrile (PhCN). Note, that compound oc in MCH was not measured as the
compound precipitates from solution after approximately 30 minutes. Spectra of compounds oc in CCl4 are
repeated for comparison from Figure 10.
– S25 –
Femtosecond transient absorption data of compound oref
oref (Tol)
10
20
Δ A / a. u.
Δ A / a. u.
20
oref (CCl4)
40
0
-20
-40
-10
-20
-30
-60
-3
oref (DCM)
0.10
0
Δ A / a. u.
60
0.05
0.00
-0.05
-0.10
-3
-80x10
-40x10
400
500
600
λ / nm
700
-0.15
400
800
500
600
700
λ / nm
500
800
600
λ / nm
700
800
-0.05
oref (PhCN)
-0.06
0
Δ A / a. u.
Δ A / a. u.
10
-10
-20
-30x10
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
-0.07
-0.08
-0.09
-0.10
-3
-0.11
400
500
600
λ / nm
700
800
600
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S18. Femtosecond transient absorption spectra and corresponding time delays of compound oref in
various solvents after photoexcitation at 530 nm. Top Left: in CCl4. Top Middle: in toluene (Tol). Top Right:
in CH2Cl2 (DCM). Bottom Left: in benzonitrile (PhCN). Note, that compound oref in MCH was not measured
as the compound precipitates from solution after approximately 30 minutes.
Femtosecond transient absorption data of compound g2c
0
0
g2c (Tol)
-20
-20
-40
g2c (DCM)
-60
-80x10
-30x10
Δ A / a. u.
-10
Δ A / a. u.
Δ A / a. u.
0
-10
-30
-3
-3
-40x10
500
600
λ / nm
700
g2c (PhCN)
-20
500
800
600
λ / nm
700
800
-3
500
600
λ / nm
700
800
-0.05
Δ A / a. u.
-0.06
-0.07
-0.08
-0.09
-0.10
-0.11
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
600
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S19. Femtosecond transient absorption spectra and corresponding time delays of compound g2c in
various solvents after photoexcitation at 640 nm. Left: in toluene (Tol). Middle: in CH2Cl2 (DCM). Right: in
benzonitrile (PhCN). Note, that compound g2c in CCl4 was not measured as the compound shows substantial
degradation of the UV/vis absorption spectrum after the measurement. Furthermore, compound g2c in MCH was
not measured as the compound precipitates from solution after approximately 30 minutes. The scattered laser
pulse is observed for the measurement in toluene.
– S26 –
Femtosecond transient absorption data of compound gc
5
5
0
gc (Tol)
-10
-15
-20
-20
Δ A / a. u.
0
Δ A / a. u.
Δ A / a. u.
0
-5
gc (DCM)
-40
-5
-10
gc (PhCN)
-15
-20
-3
-25x10
-60x10
400
500
600
λ / nm
700
-3
-25x10
400
800
500
600
700
λ / nm
-3
800
400
500
600
λ / nm
700
800
-0.05
Δ A / a. u.
-0.06
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
-0.07
-0.08
-0.09
-0.10
-0.11
600
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
750
λ / nm
800
Figure S20. Femtosecond transient absorption spectra and corresponding time delays of compound gc in various
solvents after photoexcitation at 640 nm. Left: in toluene (Tol). Middle: in CH2Cl2 (DCM). Right: in
benzonitrile (PhCN). Note, that compound gc in CCl4 was not measured as the compound shows substantial
degradation of the UV/vis absorption spectrum after the measurement. Furthermore, compound gc in MCH was
not measured as the compound precipitates from solution after approximately 30 minutes. The scattered laser
pulse is observed for the measurements in toluene and benzonitrile.
Femtosecond transient absorption data of compound gref
10
gref (Tol)
-3
-10
Δ A / a. u.
Δ A / a. u.
Δ A / a. u.
-10
0
0
0
gref (DCM)
-20
-30
-20x10
-40x10
400
500
600
λ / nm
700
-20
gref (PhCN)
-30
-40
-3
-50x10
400
800
-10
500
600
λ / nm
700
800
-3
400
500
600
λ / nm
700
800
-0.05
Δ A / a. u.
-0.06
-0.07
-0.08
-0.09
-0.10
-0.11
600
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S21. Femtosecond transient absorption spectra and corresponding time delays of compound gref in
various solvents after photoexcitation at 640 nm. Left: in toluene (Tol). Middle: in CH2Cl2 (DCM). Right: in
benzonitrile (PhCN). Note, that compound gref in CCl4 was not measured as the compound shows substantial
degradation of the UV/vis absorption spectrum after the measurement. Furthermore, compound gref in MCH
was not measured as the compound precipitates from solution after approximately 30 minutes.
– S27 –
Femtosecond transient absorption data of compound r2c
5
-5
-10x10
0
-10
-20
-10
-20
-3
-3
-30x10
-3
-30x10
500
600
λ / nm
700
800
500
600
λ / nm
700
800
500
r2c (DCM)
r2c (PhCN)
0
Δ A / a. u.
-5
-10
-0.06
Δ A / a. u.
5
0
-5
-10
-3
600
λ / nm
700
-0.08
-0.09
-0.11
-20x10
500
700
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
-0.07
-0.10
-15
-3
-15x10
600
λ / nm
800
-0.05
10
5
Δ A / a. u.
r2c (Tol)
0
Δ A / a. u.
0
10
r2c (CCl4)
10
Δ A / a. u.
Δ A / a. u.
r2c (MCH)
800
500
600
λ / nm
700
800
600
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
750
λ / nm
800
Figure S22. Femtosecond transient absorption spectra and corresponding time delays of compound r2c in
various solvents after photoexcitation at 530 nm. Top Left: in methylcyclohexane (MCH). Top Middle: in CCl4.
Top Right: in toluene (Tol). Bottom Left: in CH2Cl2 (DCM). Bottom Middle: in benzonitrile (PhCN). The
scattered laser pulse is observed for all measurements.
Femtosecond transient absorption data of compound rc
-10
-10
-20
-15
0
-5
-10
-15
-3
-20x10
λ / nm
700
800
400
10
Δ A / a. u.
5
0
-10
-20
500
600
λ / nm
700
400
-0.06
0
-5
-10
-0.07
-0.08
-0.09
-0.10
-3
-20x10
400
500
600
λ / nm
700
800
-0.11
400
500
500
600
λ / nm
700
800
-0.05
rc (PhCN)
-15
-3
-3
800
Δ A / a. u.
600
rc (DCM)
10
ΔA / a. u.
rc (Tol)
-30x10
-3
500
-30x10
5
0
Δ A / a. u.
Δ A / a. u.
Δ A / a. u.
0
-5
-20x10
rc (CCl4)
10
rc (MCH)
5
600
λ / nm
700
800
600
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S23. Femtosecond transient absorption spectra and corresponding time delays of compound rc in various
solvents after photoexcitation at 530 nm. Top Left: in methylcyclohexane (MCH). Top Middle: in CCl4. Top
Right: in toluene (Tol). Bottom Left: in CH2Cl2 (DCM). Bottom Middle: in benzonitrile (PhCN). The scattered
laser pulse is observed for the measurements in methylcyclohexane, CCl4, toluene and benzonitrile.
– S28 –
Femtosecond transient absorption data of compound rref
10
0
0
-5
-10
-15
-3
-20x10
-20x10
600
λ / nm
700
10
rref (DCM)
Δ A / a. u.
Δ A / a. u.
0
-10
-20
500
600
λ / nm
700
800
400
rref (PhCN)
-0.06
0
-10
-20
-30x10
-3
-0.07
-0.08
-0.09
-0.10
-3
-0.11
400
500
600
λ / nm
700
800
400
500
600
λ / nm
-3
500
600
λ / nm
700
800
-0.05
-30
-40x10
-20
-30x10
400
800
-10
-3
Δ A / a. u.
500
10
0
Δ A / a. u.
-10
rref (Tol)
rref (CCl4)
5
Δ A / a. u.
Δ A / a. u.
rref (MCH)
700
800
600
2 ps
3 ps
4 ps
6 ps
8 ps
16 ps
650
32 ps
65 ps
127 ps
256 ps
520 ps
710 ps
700
λ / nm
750
800
Figure S24. Femtosecond transient absorption spectra and corresponding time delays of compound rref in
various solvents after photoexcitation at 530 nm. Top Left: in methylcyclohexane (MCH). Top Middle: in CCl4.
Top Right: in toluene (Tol). Bottom Left: in CH2Cl2 (DCM). Bottom Middle: in benzonitrile (PhCN). The
scattered laser pulse is observed for the measurements in methylcyclohexane and benzonitrile.
Photoexcitation of the green compound gc in toluene at 640 nm (for spectra see Figure S20)
leads to ground state bleaching below 715 nm and to the stimulated fluorescence emission
between 715–740 nm, observed as a combined negative signal. Note, that for solutions of
compound g2c in MCH precipitation was observed after ca. 30 minutes, and that for solutions
of compound gc and g2c in CCl4 substantial light-induced degradation takes place.
Furthermore, the spectra show a small broad and positive absorption feature that extends from
470 nm to 570 nm, and a higher energy transition centered at 430 nm (bleach), which is likely
due to the higher excited state transition of the perylene unit. The transient absorption spectra
of the green reference compound gref and g2c reveal very similar features and are also in
good agreement with spectral data reported in the literature (for spectra see Figures S19 and
S21). Accordingly, no excited state interaction of the green PBI units has been observed in the
spectra; and upon varied solvent polarity only minor changes in band shapes and general
features have been found.
– S29 –
The femtosecond transient absorption spectra of the red compounds rc and r2c in MCH
(lowest polarity solvent, hence strongest interaction of dye units expected) following photoexcitation at 530 nm both display a broad absorption centered at 700–740 nm due to excited
state absorption, a strong bleach of the ground state below 590 nm, and a band between 600–
640 nm due to the stimulated emission from the lowest excited singlet state of the perylene
unit (see Figures S22 and S23). These bands are in very good agreement with the excited state
properties of the red reference compound rref in MCH (for spectra see Figure S24) and with
those reported in the literature. Interestingly, within the time frame of the experiment, the
negative band at 590 nm (observed for all red compounds (r2c, rc, rref) slightly shifts the
position of its maximum to 610 nm which might be attributed to excited state conformational
changes of the red perylene bisimide dye.S25 However, no excited state interaction of the red
PBI units has been observed in the spectra; and upon varied solvent polarity only slight
changes in band shapes and general features have been found.
– S30 –
Global and Target Analysis.
0.10
0.10
o2c (Tol)
o2c (CCl4)
0.05
0.00
solvation, 1.2 ps
oPBI*, 9.1 ps
oPBI CT, 30 ps
oPBI excimer, 192 ps
oPBI triplett
-0.05
A
-0.10
400
450
500
550
600
650
700
750
Δ A / a. u.
Δ A / a. u.
0.05
0.00
-0.05
solvation, 1.2 ps
oPBI*, 18 ps
oPBI CT, 53 ps
oPBI excimer, 111 ps
oPBI triplett
-0.10
B
-0.15
400
800
450
500
0.04
0.10
o2c (DCM)
Δ A / a. u.
Δ A / a. u.
0.00
-0.05
solvation, 0.7 ps
oPBI*, 6.5 ps
oPBI CT, 53 ps
oPBI triplett
C
450
500
550
600
650
700
750
800
o2c (PhCN)
0.02
0.05
400
600
λ / nm
λ / nm
-0.10
550
650
700
750
0.00
-0.02
solvation, 1.8 ps
oPBI*, 7.3 ps
oPBI CT, 63 ps
oPBI triplett
-0.04
-0.06
800
λ / nm
400
D
450
500
550
600
650
700
750
800
λ / nm
Figure S25. Species-associated difference spectra (SADS) of compound o2c in various solvents resulting from
the target analysis of femtosecond transient absorption data using the kinetic scheme depicted in Figure 12.
Shown are processes after photoexcitation at 530 nm, features due to Raman scattering were omitted for clarity.
A (top left): in CCl4. B (top right): in toluene (Tol). C (bottom left): in CH2Cl2 (DCM). D (bottom right): in
benzonitrile (PhCN).
– S31 –
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(S25) Similar behavior is also known from single molecule spectroscopy for the red
perylene bisimides bearing phenoxy substituents at the bay positions that were immobilized in
a polymer matrix. It is known that local reorganizations in the vicinity of the molecule have
an impact on the orientation of the phenoxy substituents for these red PBIs. For details, see:
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De Schryver, F. C. Chem. Phys. Lett. 2001, 333, 255–263. For a recent study for processes in
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– S34 –