Truxene-bridged Bodipy fullerene tetrads without precious metals: Study of the energy transfer and application in triplet-triplet annihilation upconversion

Article abstract of DOI:10.1039/d0tc03490h

Fullerenes can generate a triplet state efficiently without invoking the heavy-atom effect. However, their weak absorption in the visible spectral range makes fullerenes not an ideal triplet photosensitizer (PS). Herein, novel truxene-bridged fullerene and Bodipy tetrads were prepared by attaching Bodipy or Zn-porphyrin units (T-2B-C₆₀and T-B-C₆₀-P) which show a stronger absorption band in the visible spectral range, and the maximum molar absorption coefficient is up to 5.63 × 10⁵M^-1cm^-1at 428 nm for T-B-C₆₀-P. These tetrads show efficient singlet energy transfer from the Bodipy moiety to the fullerene/Zn-porphyrin moiety, the energy transfer rate constant is 2.72 × 10⁹s^-1and the efficiency is up to 90% for T-2B-C₆₀. Electrochemical and computational studies show that T-B-C₆₀-P exhibits photo electron transfer from fullerene to Zn-porphyrin and a T-B-C₆₀^--P⁺charge-separated state is formed. Nanosecond time-resolved transient difference absorption spectra show that the triplet excited state of T-B-C₆₀-P is distributed on both the fullerene moiety and the Zn-porphyrin moiety, which can be used as the triplet PS for two-color excitable triplet-triplet annihilation upconversion, with a large anti-Stokes shift of 4074 cm^-1

Full text of DOI:10.1039/d0tc03490h

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DOI: 10.1039/D0TC03490H
ARTICLE
Truxene−bridged Bodipy fullerene tetrads without precious
metals: study of the energy transfer and application in
Triplet−Triplet annihilation upconversion
Received 00th January 20xx,
Accepted 00th January 20xx
Yuanyuan Che,a,b.c,† Xuemei Yuan,a,† Lei Sun a, Haijun Xu,*,a Xiaoyu Zhao,b.cFangjian Cai, a Lang Liu,* c
and Jianzhang Zhao* b.c
DOI: 10.1039/x0xx00000x
Fullerenes can generate triplet state efficiently without invoking of heavy-atom effect. However, its weak absorption in the
visible spectral range makes fullerene not an ideal triplet photosensitizer (PSs). Herein, novel truxene-bridged fullerene and
Bodipy tetrads were prepared by attaching Bodipy or Zn−porphyrin units (T−2B−C60 and T−B−C60−P) which show stronger
absorption band in the visible spectral range, the maximum molar absorption coefficient is up to 5.63  105 M−1 cm−1 at 428
nm for T−B−C60−P. These tetrads show efficient singlet energy transfer from Bodipy moiety to fullerenes/Zn−porphyrin
moiety, the energy transfer rate constants is 2.72  109 s− and the efficiency is up to 90% for T−2B−C60. Through
1
electrochemical and computational studies, T−B−C60−P exhibits photo electron transfer from fullerene to Zn−porphyrin and
−
a T−B−C60 •−P+• charge−separated state is formed. Through nanosecond time−resolved transient difference absorption
spectra, the triplet excited states of T−B−C60−P is distributed on both the fullerene moiety and the Zn−porphyrin moiety,
which can be used as triplet PS for two-color excitable triplet−triplet annihilation upconversion, with a large anti−Stokes
shift of 4074 cm−
.
1
However, this method is not applicable for the design of novel
triplet PSs because subtle derivatization of a known triplet PS
may eliminate the ability of ISC completely[8, 25-27]. On the other
hand, there are still no explicit relationships between the
molecular structures and ISC [25, 28]. Thus it is desired to develop
a general molecular structure that can be used to prepare new
triplet PSs with wider absorption band through easy
functionalization.
Fullerenes have attracted attention in photochemistry
because of their good electron accepting ability. Fullerenes can
also be used as an electron spin converter to generate triplet
energy with efficiency close to unity[29]. However, fullerenes are
not an ideal triplet PS due to very weak absorption in the region
range (400–650 nm)[30, 31]. The most typical approach to
enhance the absorption in the visible range is through the
introduction of visible light-harvesting chromophores based on
intramolecular energy funneling (such as resonance energy
transfer or photoinduced electron transfer)[32-37]. These PSs
show broadband absorption in the visible region, however,
these PSs only make use of a small part of the visible spectral
range to generate triplet state and for singlet oxygen
photosensitizing or photocatalysis. Thus, it would be highly
necessary to develop novel triplet PSs with a wider absorption
band, which can efficiently harvest panchromatic light
excitation to generate triplet state.
Introduction
Triplet photosensitizers (PSs) continue to attract considerable
attention because they can be used in singlet oxygen
generation, photovoltaics, photocatalysis, photoredox catalytic
synthetic organic reactions, photodynamic therapy and triplet–
triplet annihilation upconversion (TTA-UC) [1-12]. Conventional
triplet PSs are usually obtained by the introduction of a heavy
atom, such as Pt(II), Pd(II), Ru(II), Re(I), Os, Ir(III), I and Br,
because the heavy
crossing (ISC) to generate triplet states[13-22]. A small number of
other triplet PSs are obtained by establishing a n–
transition[23, 24]. However, these triplet PSs suffer from
drawbacks, such as difficult and costly preparation, weak
absorption in the visible range, and narrow absorption band
which cannot fully utilize the broadband solar light. Thus, it is
highly desirable to develop novel heavy atom-free triplet PSs
with wider and stronger absorption band.
−atom effect can enhance the intersystem

–

*

*
A general method for the preparation of new fluorescent
molecules is the derivatization of a known fluorophore.
a. Co-Innovation Center for Efficient Processing and Utilization of Forest Products,
College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037,
China. E-mail: xuhaijun@njfu.edu.cn.
b. Key Laboratory of Energy Materials Chemistry, Ministry of Education; College of
Chemistry; Institute of Applied Chemistry, Xinjiang University, Urumqi 830046,
Xinjiang, China. E-mail: llyhs1973@sina.com
Truxene is a C3-symmetric polycyclic aromatic
platform with good coplanarity and good thermal
stability and exhibit excellent application prospects in
constructing active materials as a promising building
c. State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian
University of Technology, E-208 West Campus, 2 Ling-Gong Road, Dalian 116024,
P. R. China. E-mail: zhaojzh@dlut.edu.cn
† These authors equally contribute to this work.
Electronic Supplementary Information (ESI) available: [details of any supplementary block in
p
hotoluminescence, organic
electronics, liquid
information available should be included here]. See DOI: 10.1039/x0xx00000x
crystals and gels, and so on
.
[38] Moreover, the truxene unit
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DOI: 10.1039/D0TC03490H
Scheme 1. Molecular structure of compounds used in studies (T stands for Truxene, B stands for Bodipy, C60 stands for fullerene, P stands for zinc porphyrin)
can be easily functionalized in three directions at C-2,
C-7 and C-12 positions to serve as excellent scaffold for
the design of large star-shaped architecture.[39] Many
diads, triads or more based on truxene linking different
Results and discussions
Synthesis
chromophores have been synthesized and shown some potential
The synthesis of the tetrads T-2B-C60 and T-B-C60-P is shown in
ESI, and the details are given in the Experimental Section.
Briefly, the key intermediate 7,12-dibromotruxene-2-
carbaldehyde derivatives were prepared with 1-indanone as the
starting material according to the reported literature.[47] The
41]
applications in the area of solar cells,[40,
two-photon
absorption,[42] organic light-emitting diodes (OLED),
and
[43]
organic fluorescent probes[44]. In addition, truxene has been
proven to be a appealing building block to construct multi-
modular D-A systems for application in different energy transfer
porphyrin derivatives
dihydrodipyrromethane by modified previously reported
method.[48] Compound
was obtained by Pd-catalyzed Suzuki
4
were synthesized from 5-
studies [45, 46]
.
To address the aforementioned challenges and considering
the distinguishing properties of truxene moiety, we
prepared novel truxene bridged Bodipy, zinc porphyrin, and
fullerenes tetrads through introducing chromophore of Bodipy
and zinc porphyrin units (Scheme 1). This method is useful for
designing triplet PSs with wider absorption band, especially,
without relying on precious metals. Through the introduction of
zinc porphyrin unit, the tetrads can efficiently harvest
broadband excitation light to generate triplet state. The process
of the singlet energy transfer of these tetrads was studied by
5
coupling of 5,5’,10,10’,15,15’-hexaethyl-7, 12-dibromo-
truxene-2-carbaldehyde with BODIPY-B[49] and could be
isolated in 12% yield from mono-substituted side products by
silica gel chromatography followed by recrystallization in
appropriate solvent mixtures. Similarly, T-B and compound
6
were synthesized in sequence via a Pd-catalyzed Suzuki cross-
coupling reaction of 5,5’,10,10’,15,15’-hexabutyl-7,12-
dibromotruxene-2-carbaldehyde with 1 equiv BODIPY-B and
then compound 4, resulting in 30% and 26% yield, respectively.
The target dyads tetrads T-2B-C60 and T-B-C60-P were obtained
by the subsequent 1,3-dipolar cycloadditions using C60 and N-
steady
and the triplet energy transfer was also studied through
nanosecond time resolved transient absorption
−state UV−vis absorption, fluorescence spectroscopy,
−
methylglycine (sarcosine) with compounds
5 or 6 in refluxing
spectroscopies. Moreover, these tetrads can be used as triplet
PSs for triplet−triplet annihilation upconversion (TTA-UC).
Therefore, our results are very useful for the design and
preparation of new TTA-UC materials because there are not any
precious metals used in these tetrads.
toluene, in 63% and 62% yield, respectively. The molecular
structures of all new compounds were confirmed by NMR, and
HRMS (see ESI).
UV−vis absorption and fluorescence spectra
8 | J. Name., 2012, 00, 1-3
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The UV vis absorption spectra of the compounds were studied
ARTICLE
−
80
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TD-BOI: 10.1039/D0TC03490H
T-2B-C60
in toluene (Figure 1 and Table 1).
T
−
B
shows the characteristic
60
40
20
0
6
T-B-C60-P
T-B
T-2B-C60
4
T-B-C60-P
2

500
600
700
800
Wavelength / nm
Figure 3. Fluorescence emission spectra of
Toluene. Optically matched solutions were used (the solutions in each figure show
the same absorbance at the excitation wavelength, ex = 470 nm). 25 °C.
T−B, T−2B−C60 and T−B−C60−P in
0

300 400 500 600 700
Wavelength / nm
T−B−C60−P also exhibits a strong absorption band at 428 nm and
two weak ones at 556 and 597 nm, which are assigned to the
Soret band (S2) and the Q bands (S1(v=1) and (v=2)) of
Figure 1. UV−vis absorption spectra of T−B, T−B−C60 and T−B−C60−P in toluene. c
= 1.0 × 10−5 M, 25 °C.
Zn
shows broader absorption band, which can be more efficient for
the harvesting of solar light. C60 shows strong
absorption at Soret band, the fluorescence emission spectra of
compound C60 under direct excitation within the Soret
band (ex = 405 nm) were studied in different solvent with
optical density matched solutions (Figure 2). C60 exhibits
five emission bands in toluene, which are attributed to the
emission bands of the S2 states of Zn-porphyrin (445 nm),
solvent Raman scattering peak (471 nm), Bodipy (519 nm), S1
state (v = 2) (601 nm) and S1 state (v = 1) (647 nm ) of
−porphyrin, respectively. Compared to T−2B−C60, T−B−C60−P
30
20
10
0
Tol
THF
DCM
MeCN
T
−
B−
−P
T
−
B−
−P
T
−
B−
−P
500 600 700 800
Wavelength / nm
Zn−porphyrin unit, respectively. The result indicates that the
energy of the S2 states of Zn-porphyrin can generate
fluorescence by radiation transition, and transfer to the Bodipy
moiety by resonance energy transfer, and transfer to the S1
Figure 2. Fluorescence emission spectra of
Optically matched solutions were used (the solutions in each figure show the same
absorbance at the excitation wavelength, ex = 405 nm). 25 °C.
T−B−C60−P in different solvent.

state of Zn
absorption and fluorescence spectra, the energy of the first and
second singlet state of Zn porphyrin and the first singlet state
−porphyrin via internal conversion. According to the
absorption of the truxene and Bodipy units, which is centered
at 314 nm and 503 nm, respectively. For these tetrads, i.e.
T−2B−C60 and T−B−C60−P, absorption bands centered at 323 nm
−
of Bodipy are 2.08 eV, 2.44 eV and 1.75 eV, respectively.
and 503 nm are observed, which is the characteristic absorption
of the C60 and Bodipy moiety, respectively. Moreover,
Table1. Photophysical Properties of the compounds
b
c
abs a /nm

em
F / %
 F d /ns
 T e / μs
 g / %
74.8 k / 68.2 l/ 65.9
m / 40.1 n
f
f
T−B
314 / 503
0.64 / 0.74
525
3.19
−
−
9.16 k / 7.04 l/ 9.50
T−2B−C60
T−B−C60−P
323 / 503
1.72 / 2.09
522
0.20
32.5
37.6
89
m / 1.08 n
l
323 / 428 / 504 /
556 / 597
1.16 / 5.63 / 0.88 /
0.21 / 0.10
445 / 519 / 601 /
647
1.99 k / 1.80
/
3.82 / 1.93 /
0.84 / 0.85
39.3
1.77 m / 0.32 n
a In toluene (1.0 × 10−5 M). b Molar absorption coefficient.  : 105 M−1 cm−
.
c Fluorescence quantum yields. B−1 (F = 72 % in THF) for T−B. B−2 (F = 2.7 % in MeCN)
1
was used as standard for T−2B−C60 and T−B−C60−P. k in Tol, l in THF, m in DCM, n in MeCN. d Fluorescence lifetimes at 520 nm. ex = 445 nm. c = 1.0×10−5 M in toluene.
e Triplet state lifetimes, measured by transient absorptions. ex = 493 nm, the decay trace of these compounds at 503 nm. c = 1.010−5 M in toluene. f Not applicable.
This journal is © The Royal Society of Chemistry 20xx
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ARTICLE
Journal Name
g
Singlet oxygen quantum yields in TOL. B-2 ( = 82 % in DCM) was used as standard. The excitation wavelength ex = 510 nm for T−2B−C60, ex = 550 nm for
View Article Online
T−B−C60−P.
DOI: 10.1039/D0TC03490H
300 T-B
T-2B-C60
400
300
200
100
0
Tol
Tol
T-B-C60-P
150
100
50
THF
DCM
MeCN
THF
DCM
MeCN
Tol
200
100
0
THF
DCM
MeCN
0
500
600
700
800
500
600
700
500
600
700
Wavelength / nm
Wavelength / nm
Wavelength / nm
Figure 4. Fluorescence emission spectra of T−B, T−2B−C60 and T−B−C60−P in different solvent. Optically matched solutions were used (the solutions in each figure show the same
absorbance at the excitation wavelength, ex = 470 nm). 25 °C.
c
a
b
1000
100
10
1000
100
10
1000
100
10
F= 0.2 ns (94%)
F= 0.1 ns (86%)
F= 3.2 ns
F= 3.0 ns (14%)
F= 3.1 ns (6%)
0
10 20 30 40 50
0
10 20 30 40 50
0
10 20 30 40 50
Times / ns
Times / ns
Times / ns
Figure 5. Fluorescence decay curves of T−B (a), T−2B−C60 (b), and T−B−C60−P(c) at 520 nm in toluene. Excited with a 445 nm picosecond pulsed laser.
The emission spectra and fluorescence quantum yields of is the characteristic emission of Bodipy moiety, moreover,
these compounds upon photoexcitation at 470 nm (the
characteristic absorption of Bodipy) in toluene were studied nm and 650 nm, which are ascribed to the characteristic
(Table 1 and Figure 3). gives a very strong emission band at emissions of the S1 state of Zn porphyrin. This ensures that the
522 nm (F = 74.8%), however, the fluorescence intensity of singlet energy of Bodipy can transfer to the S1 state of
these tetrads are significantly reduced ( F = 7.1% for 2C60 Zn porphyrin via the Förster resonance energy transfer (FRET).
F = 2.0% for C60 ). The above result indicates that these For , the fluorescence intensity decreases slightly with
tetrads exhibit singlet singlet energy transfer from Bodipy to increasing of the solvent polarity from toluene to acetonitrile
fullerenes ( 2B C60) / Zn
photo-excitation.
The fluorescence emission spectra of
C60
T−B−C60−P also exhibits two additional emission bands at 600
T
−
B
−

T
−
B−
,
−

T
−
B−
−
P
T−B
−
T
−
−
−
porphyrin (
T
−
B
−
−
C60−P) under the and methanol. However, the tetrad T−B−C60−P shows a highly
solvent polarity-dependent emission, as the polarity of the
T
B,
T
−
2B−
C60 and solvent increases (from toluene to acetonitrile) and the
T
−
B
−
−P under direct excitation within the characteristic emission intensity at 520 nm decreases significantly, which
absorption band of Bodipy (ex = 470 nm) were studied in indicates that PET plays an important role. The emission
different solvent with optically matched solutions (Figure 4). intensity was quenched in acetonitrile (polar solvent) compared
These compounds all show an emission band at 520 nm which with that in toluene for
T−2B−C60. The quenching of the
8 | J. Name., 2012, 00, 1-3
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ARTICLE
emission in polar solvents indicates the tetrad
exhibits intramolecular charge transfer in acetonitrile.
For T-B, the fluorescence decays with a monoexponential 1.65
feature (Figure 5), along with the lifetime as 3.2 ns. However, transfer efficiency was calculated to be 90% for
T−2B−C60 On the basis Eqns (1) and (2). The singlet energyVtierwanAsrtficelerOrnalitnee
−
1
constants was calculated to be 2.72

109 s for
, respectively. The singlet energy
2B C60 and
T−2B−C60
DOI: 10.1039/D0TC034a90nHd
−
1

109 s for
T−B−C60−P
T
−
−
for the tetrads, the fluorescence decay of the Bodipy moiety is 84% for
T
−
B
−
C60
−
P
, respectively.
1
1
with biexponential character of 0.2 ns (population is ca.
94%)/3.1 ns (ca. 6%) for 2B C60, 0.1 ns (ca. 86%)/3.0 ns (ca.
14%) for C60 , respectively, which indicate that the
fluorescence-quenching pathway is singlet singlet energy
푘ET(S1) =
−
Eqn (1)
휏
휏 °
퐹
퐹
T
−
−
T
−
B−
−P
−
transfer from the Bodipy moiety to the C60 unit for
and from the Bodipy moiety to Zn-porphyrin/ C60 for
T
−
B
2B
−
C60
,
T
−
−
C60
−
P
.
c
a
b
1
0
-1
-2
1
0
-1
-2
1
0
-1
-2
Potential / V
Potential / V
Potential / V
Figure 6. Cyclic voltammograms of
T
−
B
(a),
T
−
2B
−
C
60 (b) and T−B−C60−P
(c). Ferrocene (Fc0/+) is used as an internal reference. In degassed CH2Cl2 solutions containing
0.5 mM compound and Fc (0.5 mM), 0.10 M Bu4NPF6 is the supporting electrolyte and Ag/AgNO3 is the reference electrode. Scan rate: 50 mV s−1. T = 20 °C.
Table 2. Redox potentials of these compounds a
Compound
Oxidation(V)
Reduction(V)
T–B
+0.75
+0.74
–1.69
–1.22
2B–T–C60
B−C60−T–P
+0.32
+0.37
−1.16
–1.19
B−C60−T–Co
Table
3.
Charge
a Cyclic voltammetry in N2 saturated DCM, containing a 0.10 M BuNPF6 supporting electrolyte; Counter electrode is Pt electrode; Working
electrode is glassy carbon electrode; Ag/AgNO3 couple as the reference electrode, Electrochemical potentials versus Fc(+/0). c[Ag+] = 0.1 M.
Separation
(ΔGCS) and Charge Separation Energy States (ECS) of T−2B−C60 and T−B−C60−P in different solutions.
 G CS (eV)
DCM
E CS (eV)
DCM
TOL
THF
MeCN
TOL
THF
MeCN
T
−
2B
−
C60
0.40
−0.46
−0.63
−0.54
−0.69
−0.79
−0.86
2.82
2.03
1.97
1.44
1.89
1.39
1.64
1.22
T−
B
−
C60
−
P
−0.05
The singlet excited state of T
−
2B−
C60 (2.40 eV) and T−B−C60−P (2.08 eV) as E00.
1
1
(
−
)
°
energy donor in the presence of energy acceptor; kET(S1) is the
singlet energy transfers rate constants and eff is the singlet
energy transfer efficiency.
휏
휏
퐹
퐹
(
)
eff % =
Eqn (2)
1
휏
퐹
Electrochemical Measurements
Where F
absence of energy acceptor;
°
is the singlet state lifetime of the donor in the
F is the singlet state lifetime of the

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ARTICLE
In order to study the potential photoinduced electron energy changes of
Journal Name
T
−
2B
−
C60 is 0.40 eV in toluene, which
View Article Online
DOI: 10.1039/D0TC03490H
transfer (PET), the electrochemical properties of these indicates that the photo electron transfer from Bodipy to
compounds were studied with cyclic voltammetry (Figure 6) and fullerene is thermodynamically inhibited. For
their redox potentials are summarized in Table 2. The Gibbs free first oxidation wave potential is +0.32 V which is the oxidation
energy changes of the electron transfer were calculated potential of Zn porphyrin, and the first reduction wave at 1.16
according to the Weller equation (the details shows in the eV is assigned to the fullerene. The Gibbs free energy changes
supporting information) (Table 3 ).[37, 50] For
, a reversible of C60 is 0.05 eV, which indicates that the PET from
oxidation wave and a reversible reduction wave were observed, Zn porphyrin to fullerene and formation of a
and the half
respectively. For
is due to the electron-donor unit (Bodipy), and the first
reduction wave at 1.22 V is due to the electron-acceptor unit
(fullerene). According to the Weller equation, the Gibbs free
T−B−C60−P, the
−
−
T
−
B
T
−
−
B−
−
P
−
−
•
T−B−C60 −
P+•
−
wave potential (E1/2) is +0.75 V and −1.68 V, charge-separated state is thermodynamically allowed.
2B C60, the first oxidation wave at +0.74 V
T
−
−
−
T
−
2B−
C60
T−B−C60−P
Figure 7. The optimized ground state geometry of T−2B−C60 and T−B−C60−P
HOMO
LUMO
Figure 8. Electron-density maps of the frontier molecular orbitals of T−B−C60−P
−
•
DFT computation
state and T−B−C60 −
P+• charge-separated state as a result of
the photo-induced electron transfer.
Nanosecond Transient Absorption Spectroscopy
The ground state geometries of
optimized (Figure 7). The center-to-center distance of
T
−
2B
−
C60 and
T
−
B
−
C60
T
−
−
P
were
−
2B C60
between the electron donor and the electron acceptor was To investigate the triplet state properties of the compounds,
found to 21.4 Å, which is slightly longer than that of C60 the nanosecond time resolved transient difference absorption
(18.1 Å). The radius of Bodipy, Zn porphyrin and fullerene was spectra were measured upon pulsed laser excitation at 493 nm
4.2 Å, 8.9 Å and 3.5 Å, respectively. The frontier orbitals of (Figure 9). For 2B C60, a ground state bleach (GSB) band at
2B C60 and C60 are shown in Figure 8 and Figure S15. 330 nm was observed which is in agreement with the steady-
Importantly, the HOMO was found to be Bodipy moiety for state UV absorption band of fullerene. Moreover, a broad
2B C60 and Zn porphyrin moiety for C60 , respectively. excited state absorption (ESA) band in the range of 600−800 nm
The LUMO of 2B C60 and C60 was fully localized on
T
−
B−
−
P
−
−
−
T
−
−
T
−
−
T
−
B−
−P
T
−
−
−
T
−
B−
−P
T
−
−
T
−
B
−
−P
the fullerene entity. The confinements of the HOMO and LUMO
−
also suggest the formation of a
T
−
2B+•
−
C60 • charge-separated
8 | J. Name., 2012, 00, 1-3
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Page 7 of 13
Journal of Materials Chemistry C
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Journal Name
ARTICLE
0.02
0.00
was observed, which is ascribed to the characteristic absorption
12.49 us
......
View Article Online
of the triplet state of fullerene.[36, 37, 51] However, the bleaching
DOI: 10.1039/D0TC03490H
0.02
0.01
0.00
0.892 us
0 us
of the Bodipy moiety was not observed. Thus, the triplet state
localized at the fullerene moiety indicates the singlet energy
from Bodipy to the fullerene moiety because the Bodipy moiety
is selectively excited and the Bodipy unit is without any ISC
ability. The lifetime of the triplet state was determined as 32.4
133.7 us
......
-0.02
14.8 us
0 us
-0.04
b
a
300 400 500 600 700
Wavelength / nm
300 400 500 600 700
Wavelength / nm

s. For
−
T
−
B
−
C60
−
P
, the GSB band at 429 nm is due to the
2B C60, there have broad ESA
Zn porphyrin unit. Just like
T
−
−
0.02
c
d
bands in the range of 600−800 nm, which is the feature
absorption of the T1 state of fullerene. The result indicates the
triplet state is delocalized at both the fullerene moiety (ET1 =ca.
0.04
=  s
=  s
0.01
0.00
1.60 eV for native C60) and Zn
eV),[33, 52-55] and there is singlet energy from Bodipy to the
fullerene moiety and the Zn porphyrin moiety. The triplet state
lifetime of C60 with pulsed-laser excitation at 493 nm is
37.6 s.
−porphyrin moiety (caET1 = ca. 1.61
0.02
0.00
−
T
−
B−
−P
0
200 400 600 800
0
50
100 150

Times / s
Times / s
Triplet-triplet annihilation upconversion
Figure 9. Nanosecond time-resolve transient difference absorption spectra.
Transient spectra of 2B 60 (a) and C60
(b), c = 5.0 × 10−6 M in deaerated
2B 60 (c) and C60 (d) at 503
C.
Based on the triplet state level of fullerene (ca. 1.6 eV)[33, 55], we
selected perylene (Py. 1.53 eV) as the triplet acceptor and
T
−
−
C
T
−
B
−
−P
toluene (

ex = 493 nm). The decay trace of
T
−
−
C
T
−
B
−
−P
nm. c = 1.0 × 10− M in deaerated toluene .25

emitter for TTA-UC[56]. For triplet PSs
T
−
2B−
C60, the excitation
600
without Py
with Py
*
a Excited with 510 nm laser
400
200
0
c
P1
P1+Py
P2
P2+Py
Excited with 589 nm laser
b
500 600 700 800
Wavelength / nm
Figure 10. The TTA upconversion fluorescence spectra: T-2B-C60 as the photosensitizer
with triplet acceptors Py. (c[photosensitizer] = 1.0  10− M, c[Py] = 1.3  10− M).
5
3
Excitation was with 510 nm laser (48 mW cm−2).
300
d
a
*
L1
b
*
P2
P2+Py
P2+PBI
100
50
0
L2
L1+L2
200
100
0
Figure 12. The photographs of the emission and CIE diagram of the sensitizer alone
and the upconversion. (a) and (c): λex = 510 nm ( 48 mW cm−2); (b) and (d) λex = 589
nm (153 mW cm−2). P1 stands for the compound of
2B 60. P2 stands for the
compound of C60
without PBI
with PBI
T
−
−C
T
−
B
−
−P.
*
wavelength was selected as 510 nm according to its absorption
band. For the triplet PSs alone, no emission at 475 nm was
observed, however, significant upconverted emission at 475 nm
was observed in the presence of Py (Figure 10), and the
upconversion quantum yields were measured as 0.2%. For
500 600 700 800
Wavelength / nm
500
600
700
800
Wavelength / nm
triplet PSs
as 510 and 589 nm, which is correspond to the S0
of the Bodipy moiety and the Zn porphyrin unit, respectively.
TTA-UC are represented in Figure 11a. The anti Stokes shift is
T
−
B
−
C60
−
P
, the excitation wavelength was selected
Figure 11. Upconversion with T−B−C60−P as triplet photosensitizer：(a) Py as triplet
acceptor. L1 stands for excitation at 510 nm (48 mW cm−2), L2 stands for excitation at 589
nm cw−laser (153 mW cm−2). L1+L2 stands for simultaneous excitation with 510 nm and
589 nm CW−laser (the two laser beams are in pseudocollinear geometry within the
cuvette). c [Py] = 5.0  10−4 M. (b) PBI as triplet acceptor. Excited with 589 nm cw-laser
→
S1 transition
−
−
1445 cm− and 4075 cm , respectively, and the upconversion
quantum yields were determined as 0.12% and 0.63% at the
excitation wavelength 510 nm and 589 nm, respectively.
−
1
1
−
(153 mW cm−2). c [PBI] = 6.0  10 M. The asterisks indicate the scattered laser. c
5
[photosensitizer] = 1.0  10−5 M. In deaerated toluene. 25 °C.
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Journal of Materials Chemistry C
Page 8 of 13
ARTICLE
According to the triplet level of Zn
Journal Name
−
porphyrin, the PBI was fluorescence spectra, the energy of the first and second singlet
View Article Online
DOI: 10.1039/D0TC03490H
−porphyrin moiety and the first singlet state of
selected as triplet emitter. The excitation wavelength was state of Zn
selected at 589 nm which is the S0
Zn porphyrin for the triplet triplet annihilation upconversion to the previous report, the energy of the first singlet state of
of triplet PSs C60 . No emission in the range of 545 nm fullerenes, the triplet state of fullerenes and Zn porphyrin is
was observed in the triplet PSs alone solution, however, 1.75 eV, 1.53 eV and 1.53 eV, respectively[55, 57]. In case of
significant upconverted emission at 545 nm was observed when C60 , the energy of the second singlet state of
porphyrin transfers to the first singlet state of Zn porphyrin
and Bodipy via internal conversion (IC) and singlet energy
→
S1 transition of the Bodipy are 2.88 eV, 2.08 eV and 2.68 eV, respectively. According
−
−
T
−
B−
−
P
−
T
−
−
B
−
−P
−
1
adding PBI (Figure 11b). The anti-Stokes shift was 1371 cm and Zn
the upconversion quantum yield was determined as 0.56%.
A Photophysical process of T−B−C60−P
−
The photophysical process of
T−B−C60−P was summarized in
the energy diagram (Scheme 2). Based on the absorption and
Scheme 2. Simplified diagram illustrating the photophysical processes involved in T−B−C60−P.
S1 andS2 is the first singlet state and second singlet state of Zn−porphyrin moiety, respectively. The 3(T−B−C60*−P) and 3(T−B−C60−P*) is the triplet state of fullerene and Zn−porphyrin
−
moiety, respectively. 1(T−B−C60 •−P+•) is charge-separated state. ISC, FRET, IC and CS denote intersystem crossing, Förster resonance energy transfer, internal conversion and charge
separate, respectively.
transfer, respectively. Moreover, the energy of the first singlet the electron transfer from Bodipy to fullerene for
state of Bodipy can transfer to fullerenes and Zn porphyrin thermodynamically inhibited in toluene. Furthermore, the
through singlet-singlet energy transfer, and the rate constants nanosecond time resolved transient difference absorption
and efficiency of the singlet energy transfer is calculated at 1.47 spectra suggest the triplet excited states of
T−2B−C60 is
−
−
T
−
B
−
−
C60
−
P
is
−
1

109 s and 82 %, respectively. According to the TD
−
DFT distributed on both the fullerene moiety and the Zn
porphyrin
computations, the fluorescence emission spectra in different moiety. These tetrads can be used as triplet PSs for triplet–
solvents and electrochemical studies, we speculate that triplet annihilation upconversion. The introduction of
T
−
B
−
C60
−P exhibits intramolecular electron transfer process Zn−porphyrin leads to more high upconversion quantum yields
−
•
and a
T
−
B−
C60
−
P+• charge
−
separated state could be formed (0.63%) than the introduction of Bodipy chromophore (0.2%),
Stokes shift of 4075 cm− was obtained
1
during photoinduced electron transfer. Then the S1 state of moreover, an anti
−
fullerenes and Zn
−
porphyrin entity can produce the triplet state which is larger than the anti
−
Stokes shift obtained by
−
1
3
3
(
T
−
B−
C60*−
P
) and
(
T
−
B
−
C60
porphyrin moiety, respectively, through the broad absorption band and triplet state located on two
different moieties, C60 can be used as triplet
−P*) which is localized at introducing singlet chromophore (1445 cm ). Also, due to its
fullerenes and Zn
ISC process.
−
T
−
B−
−P
photosensitizer for two-color excitable triplet
annihilation upconversion.
−triplet
Conclusions
In summary, truxene bridged Bodipy and fullerenes tetrads
2B C60 and C60 through introducing Bodipy or zinc
Experimental section
T
−
−
T
−
B−
−P
porphyrin units were prepared. Through steady-state UV−vis General
absorption and fluorescence spectral studies, the tetrads of
All chemicals and solvents were of analytical reagent grade and
used as received unless otherwise noted. CH2Cl2 was distilled
from CaH2 under N2 atmosphere. THF was distilled from
T
−
B
−
C60
to Zn porphyrin.
transfer from Zn
−
P
exhibits singlet state energy transfers from Bodipy
C60 exhibit photo-induced electron
porphyrin to fullerene in toluene, however,
−
T
−
B−
−P
−
sodium/benzophenone
N2
atmosphere.
Tetra-n-
8 | J. Name., 2012, 00, 1-3
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Page 9 of 13
Journal of Materials Chemistry C
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Journal Name
ARTICLE
butylammonium perchlorate (TBAP) from Sigma Chemical was 8.12-8.15 (m, 4 H), 7.82-7.84 (m, 2 H), 7.72-7.78 (m, 2 H), 1.55-
View Article Online
DOI: 10.1039/D0TC03490H
recrystallized from ethyl alcohol and dried under vacuum at 40 1.57 (m, 36 H).
1
Synthesis of compound 3

C for at least one week before use. H NMR spectra were
collected on a Bruker DRX-600 AVANCE III spectrometer.
Chemical shifts for H NMR spectra were recorded in ppm
relative to CDCl3 (δ = 7.26 ppm) as the internal standard. Mass
spectra data were obtained using a Thermo Fisher LTQ Orbitrap
Zinc(II) 5, 15-3,5-di-tert-butylphenyl-10-phenylporphyrin
2
1
(0.29 mmol, 239.7 mg) was dissolved in CHCl3 (320 mL) and
cooled to 0°C. After adding [bis(trifluoroacetoxy)iodo]benzene
(0.54 mmol, 232.2 mg), I2 (0.69 mmol, 175.1 mg) and 20~25
drops of pyridine, reaction mixture was stirred at room
temperature for 48 h. Then, the reaction was quenched by the
saturated Na2S2O3 solution. The organic layer was extracted
with CH2Cl2, washed three times with distilled water, dried over
anhydrous Na2SO4, and evaporated under reduced pressure.
The product was purified by column chromatography over silica
XL (HR-ESI) spectrometer. UV
−
vis absorption spectra were
vis spectrophotometer.
recorded on UV2550 UV
a
−
Fluorescence spectra were measured on a Shimadzu RF-5301PC
spectrofluorometer. The fluorescence lifetimes were registered
on an OB920 luminescence lifetime spectrometer (Edinburgh,
U.K.).
Synthesis of Compounds
gel with petroleum ether-CH2Cl2 as eluent, affording the
1
compound
3
(112 mg, 41%). H NMR (CDCl3, 600 MHz, ppm) δ
BODIPY-B was synthesized according to the literature
method.[49] 5,5’,10,10’,15,15’-hexaethyl-7,12-dibromotruxene-
9.71 (d, J = 4.8 Hz, 4 H), 8.94 (d, J = 3.6 Hz, 2 H), 8.81-8.86 (m, 4
H), 8.20-8.22 (m, 2 H), 8.09 (dd, J = 1.8 Hz, 4 H), 7.84-7.85 (m, 2
H), 7.74-7. 81 (m, 3 H), 1.56 (d, J = 7.8, 36 H), -2.63(s, 2 H).
Synthesis of compound 4
2-carbaldehyde
and
5,5’,10,10’,15,15’-hexabutyl-7,12-
dibromotruxene-2-carbaldehyde was synthesized according to
the literature.[47]
Synthesis of compound 1
Under argon atmosphere, compound
3 (0.25 mmol, 238.1 mg),
triethylamine (7.15 mmol, 1.10 mL), Pd(PPh3)4 (0.0052 mmol,
6.0 mg) and pinacolborane (1.34 mmol, 0.19 mL) were dissolved
in dry 1,2-dichloroethane (33 mL). After 15 hour of reflux at 90
oC, the reaction mixture was cooled to room temperature.
Reaction was quenched by adding aqueous solution of KCl (30%,
5 mL) and product was extracted with CH2Cl2 (100 mL). A MeOH
solution (10 mL) containing zinc(II) acetate dihydrate (500 mg)
was added to the combined organic layer. The reaction mixture
was stirred overnight at room temperature. The solution was
washed three times with distilled water, dried over anhydrous
Na2SO4 and evaporated under reduced pressure. The crude
product was purified by column chromatography over silica gel
with petroleum ether-CH2Cl2 as eluent, affording violet
To a solution of 5-dihydrodipyrromethane (8 mmol, 1.16 g) in
degassed CH2Cl2 (1.0 L), was added 3,5-di-tert-
butylbenzaldehyde (8 mmol, 1.75 g) and TFA (0.52 mL, 7.0
mmol). Under an argon atmosphere, the solution was stirred for
5 hours at room temperature in the dark. After adding DDQ
(12.20 mmol, 2.77 g), the reaction mixture was stirred for
another one hour. Triethylamine (2.60 mL) was added and a
MeOH solution (25 mL) containing zinc(II) acetate dihydrate
(1200 mg) was added. The reaction mixture was stirred
overnight at room temperature. The organic layer was washed
three times with distilled water, dried over anhydrous Na2SO4
and evaporated under reduced pressure. The residue was
purified by column chromatography on silica gel with petroleum
compound
4
(180 mg, 76 %). UV-vis (CH2Cl2), λmax/nm[ɛ×10-
1
ether-CH2Cl2 as eluent to give compound
1
(0.73 g, 51%). H
5/(L·mol-1·cm-1)]: 420 (2.04293), 549 (0.07619), 588 (0.00952);
1H NMR (CDCl3, 600 MHz, ppm) δ 9.92 (d, J = 4.8 Hz, 2 H), 9.13
(d, J = 4.8 Hz, 2 H), 9.00 (d, J = 4.2 Hz, 2 H), 8.96 (d, J = 4.8 Hz, 2
H), 8.21-8.23 (m, 2 H), 8.10 (dd, J = 1.8 Hz, 4 H), 7.81-7.82 (m, 2
H), 7.71-7.77 (m, 3 H), 1.87 (s, 12 H), 1.56 (d, J = 6 Hz, 2 H).
Synthesis of compound 5
NMR (CDCl3, 600 MHz, ppm) δ 10.35 (s, 2 H), 9.47 (d, J = 7.2 Hz,
4 H), 9.22 (d, J = 4.2 Hz, 4 H), 8.16 (dd, J = 1.8 Hz, 4 H), 7.85-7.86
(m, 2 H), 1.60 (s, 36 H).
Synthesis of compound 2
Zn(II) 5, 15-3,5-di-tert-butylphenyl-porphyrin (0.38 mmol, 300
mg) was dissolved in distilled and degassed THF (107 mL). Under
argon, the reaction mixture was cooled to 0°C. A solution of
phenyllithium (1.6 M, 1.92 mL, 3.07 mmol) was added dropwise
during 30 min. After removing the ice-bath, the reaction
mixture was stirred for another 30 min at room temperature,
and a solution of water/THF (v/v, 3 mL/12 mL) was carefully
added. The reaction mixture was stirred for 20 min at room
temperature and DDQ (328 mg, 1.44 mmol) was poured inside
the round bottom flask. After one hour, the organic layer was
washed three times with distilled water and extracted with
CH2Cl2. The combined organic layer was dried over anhydrous
Na2SO4. The organic solvent was removed under reduced
pressure. The residues were purified by column
chromatography on silica gel with petroleum ether-CH2Cl2 as
Under an argon atmosphere, 5, 5’, 10, 10’, 15, 15’-hexaethyl-7,
12-dibromotruxene-2-carbaldehyde (0.60 mmol, 417.9 mg),
BODIPY-B (1.20 mmol, 540.2 mg), Na2CO3 (10.80 mmol, 1.14 g),
THF (70 mL), and MeOH/ water (7 mL, 1/1, v/v) were added to
the round bottomed flask. Then Pd(PPh3)4 (0.12 mmol, 1387 mg,
10 mol%) was added. The reaction mixture was refluxed and
stirred under Ar for 24 h. After completion of the reaction, the
mixture was cooled to room temperature. The reaction mixture
was extracted with CH2Cl2, washed with saturated NH4Cl
solution and water (2 × 100 mL), and dried over Na2SO4. The
solution was evaporated to dryness under reduced pressure to
give a crude solid. The crude product was further purified with
column chromatography on silica gel with petroleum ether-
CH2Cl2 as eluent to give pure product (85 mg, yield 12%). UV-vis
(CH2Cl2), λmax/nm[ɛ×10-5/ (L·mol-1·cm-1)]: 330 (0.13579), 501
(1.76283); 1H NMR (CDCl3, 600 MHz) δ 10.15 (s, 1 H), 8.56 (d, J
= 8.4, 4 H), 8.46-8.51 (m, 2 H), 8.03 (s, 1 H), 7.96 (d, J = 7.8, 1 H),
eluent to give compound
2
(160 mg, 52 %).1H NMR (CDCl3, 600
MHz, ppm) δ 10.29 (s, 1H), 9.42-9.44 (m, 2 H), 9.16-9.18 (m, 2
H), 9.05-9.07 (m, 2 H), 8.98-9.00 (m, 2 H), 8.23-8.24 (m, 2 H),
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Journal of Materials Chemistry C
Page 10 of 13
ARTICLE
Journal Name
7.92 (d, J = 7.8, 4 H), 7.78-7.81 (m, 4 H), 7.42-7.44 (d, J = 7.8, 4 λmax / nm [ɛ×10-5/(L·mol-1·cm-1)]: 329 (0.97319), 424 (6.55283),
View Article Online
1
DOI: 10.1039/D0TC03490H
H), 6.03 (s, 4 H), 3.04-3.14 (m, 6 H), 2.59 (s, 12 H), 2.28-2.36 (m, 502 (1.07515), 551 (0.26879), 593 (0.10195); H-NMR (CDCl3,
6 H), 1.52 (s, 12 H), 0.24-0.34 (m, 18 H). Esi-HRMS: calculated 600 MHz, ppm) δ 10.03-10.09 (m, 1 H), 9.15 (t, J = 4.8 Hz, 4 H),
for C78H76B2F4N4O: 1182.6141, found: 1182.6132 (M +).
Synthsis of T-B
9.10 (t, J = 4.8 Hz, 2 H), 9.05 (t, J = 4.8 Hz, 2 H), 8.81-8.86 (m, 1
H), 8.68-8.73 (m, 1 H), 8.63 (d, J = 6.6 Hz, 1 H), 8.47 (dd, J = 1.2
Hz, 1 H), 8.40 (t, J = 3.0 Hz, 1 H), 8.32 (t, J = 7.8 Hz, 2 H), 8.21 (s,
4 H), 8.12 (s, 1 H), 8.01-8.10 (m, 3 H), 7.97 (d, J = 7.8 Hz, 1 H),
7.92 (t, J = 7.2 Hz, 1 H), 7.87 (d, J = 9.0 Hz, 3 H), 7.81 (s, 3 H),
7.49-7.53 (m, 2 H), 6.07 (d, J = 7.8 Hz, 2 H), 3.16-3.43 (m, 6 H),
2.64 (s, 6 H), 2.39-2.44 (m, 4 H), 2.31-2.36 (m, 2 H), 2.64 (s, 6 H),
Under an Ar atmosphere, 5, 5’, 10, 10’, 15, 15’-hexabutyl-7, 12-
dibromotruxene-2-carbaldehyde (0.70 mmol, 605.5 mg),
BODIPY-B (0.70 mmol, 315.1 mg), Na2CO3 (12.60 mmol, 1.34 g),
THF (60 mL), and MeOH/ water (10 mL, 1/1, v/v) were added to
the round bottomed flask. Then Pd(PPh3)4 (0.07 mmol
，77.4
1.61 (m, 42 H), 1.10-1.20 (m, 12 H), 0.61-0.91 (m, 30 H). Esi-MS
calculated for C125H137BF2N6OZn: 1851.0206, found: 1852.0330
(M+H +).
:
mg, 10 mol %) was added. The reaction mixture was refluxed
and stirred under Ar for 24 h. After completion of the reaction,
the mixture was cooled to room temperature. The reaction
mixture was extracted with CH2Cl2, washed with saturated
Synthesis of T-B-C60-P
NH4Cl solution and water (2 × 100 mL), and dried over Na2SO4. Compound
7 (0.02 mmol, 37.1 mg), C60 fullerene (0.11 mmol,
The solution was evaporated to dryness under reduced 79.3 mg), and sarcosine (0.22 mmol, 19.6 mg) were dissolved in
pressure to give a crude solid. The crude product was further toluene (30 mL) under Argon, and the mixture was heated
purified with column chromatography on silica gel with under reflux for 12 h, and then cooled slowly to room
petroleum ether-CH2Cl2 as eluent to give pure product (233 mg, temperature. The solvents were removed under reduced
yield 30%). UV-vis (CH2Cl2), λmax/nm[ɛ×10-5/(L·mol-1·cm-1)]: 318 pressure. The residue was purified by column chromatography
(0.192), 502 (0.219); 1H-NMR (CDCl3, 600MHz, ppm) δ 10.15 (s, using petroleum ether-CH2Cl2 as the eluent to give the product
2 H), 8.44-8.48 (m, 1 H), 8.25-8.28 (m, 1 H), 7.92-7.96 (m, 3 H), T-B-C60-P (34.7 mg, yield 62%). UV-vis (CH2Cl2), λmax / nm[ɛ×10-
7.44 (d, J = 6 Hz, 2 H), 7.61 (s, 1 H), 6.02 (s, 2 H), 2.92-3.03 (m, 6 5/(L·mol-1·cm-1)]: 257 (1.32673), 316 (0.78043), 424 (3.56396),
1
H), 2.09-2.24 (m, 6 H), 1.54 (d, J = 12 Hz, 6 H), 0.44-0.52 (m, 26 502 (0.57231), 549 (0.14308), 590 (0.039020); H-NMR (CDCl3,
H). Esi-MS: calculated for C71H82BBrF2N2O: 1108.5672, found: 600 MHz, ppm) δ 9.04-9.06 (m, 4 H), 9.00 (t, J = 3.0 Hz, 2 H), 8.96
1108.5592 (M +).
Synthesis of compound T-2B-C60
(s, 2 H), 8.71-8.73 (m, 1 H), 8.53 (t, J = 3.6 Hz, 2 H), 8.42-8.46 (m,
1 H), 8.29 (s, 2 H), 8.23 (s, 2 H), 8.09-8.14 (m, 5 H), 7.95 (t, J = 6.6
Hz, 2 H), 7.85 (s, 1 H), 7.74-7.80 (m, 7 H), 7.42-7.44 (d, J = 7.2 Hz,
2 H), 6.02 (s, 2 H), 5.05 (s, 1 H), 4.94-4.96 (m, 1 H), 4.21-4.22 (m,
1 H), 3.28-3.31 (m, 2 H), 3.04-3.07 (m, 4 H), 2.95 (s, 3 H), 2.58 (s,
6 H), 2.28-2.40 (m, 6 H), 1.53 (s, 36 H), 1.51 (s, 6 H), 1.04-1.11
(m, 6 H), 0.56-0.68 (m, 30 H). Esi-MS: calculated for
C187H142BF2N7Zn: 2598.0679, found: 2599.0908 (M+H +).
Measured method of Compounds
Compound
5 (0.020 mmol, 21.1 mg), C60 fullerene (0.02 mmol,
17.3 mg), and sarcosine (0.08 mmol, 7.0 mg) were dissolved in
toluene (30 mL) under Argon, and the mixture was heated
under reflux for 12 h, and then cooled slowly to room
temperature. The solvents were removed under reduced
pressure. The residue was purified by column chromatography
using petroleum ether-CH2Cl2 as the eluent to give the product
T-B-C60 (23.8 mg, yield 63%). UV-vis (CH2Cl2), λmax/nm[ɛ×10-
5/(L·mol-1·cm-1)]: 260 (0.82061), 340 (0.62752), 501 (0.71441);
1H-NMR (CDCl3, 600 MHz, ppm) δ 8.43-8.47 (m, 2 H), 8.37-8.40
(m, 1 H), 7.90 (d, J = 7.8 Hz, 4 H), 7.75-7.79 (m, 5 H), 7.41 (d, J =
7.8 Hz, 4 H), 6.02 (s, 4 H), 5.12 (s, 1 H), 5.08 (d, J = 9.6 Hz, 1 H),
4.36 (d, J = 9.6 Hz, 1 H), 2.99-3.11 (m, 6 H), 2.96 (d, J = 1.2 Hz, 1
H), 2.58 (s, 12 H), 2.24-2.30 (m, 6 H), 1.51 (s, 12 H), 0.28-0.30 (m,
18 H). Esi-MS: calculated for C140H81B2F4N5: 1929.6614, found:
1910.6512 (M-F -).
Singlet Oxygen Quantum Yields Determination
The singlet oxygen quantum yields (ΦΔ) of these compound was
recorded in toluene with
B−2 as the standard ( = 82 % in
DCM). 1,3
−
Diphenylisobenzofuran (DPBF) was used as 1O2
scavenger. The solutions of the compound and the standard
should give the same absorbance (adjusted to around 0.2−0.3)
at the excitation wavelength (510 nm for
T−2B−C60, 550 nm for
T
−
B−
C60−P
). The 1O2 production was measured by following the
absorbance of DPBF at 414 nm upon photo-irradiation of the
compound/DPBF mixed solution, the absorbance of DPBF at 414
nm should be adjusted to around 1. The Δ was calculated
according to equation eq 3:
Synthesis of compound 6
Under an Ar atmosphere, compound T-B (0.15 mmol, 166.2 mg),
4
(0.15 mmol, 144.4 mg), Na2CO3 (2.70 mmol, 286.1 mg), THF
(40 mL), and MeOH/water (4 mL, 1/1, v/v) were added to the
round bottomed flask. Then Pd(PPh3)4 (0.02 mmol, 17.3 mg)
was added. The reaction mixture was refluxed and stirred under
Ar for 24 h. After completion of the reaction, the mixture was
cooled to room temperature. The reaction mixture was
extracted with CH2Cl2, washed with saturated NH4Cl solution
and water (2 × 50 mL), and dried over Na2SO4. The solution was
evaporated to dryness under reduced pressure to give a crude
solid. The crude product was further purified with column
chromatography on silica gel with petroleum ether-CH2Cl2 as
2
− A
std




K
1−10
std  sam 
 sam 
std

(eqn 3)
 =
Kstd 1−10− A
sam



Where “sam” and “std” represent the sample and the standard. And
Φ, A, K, and η represent the singlet oxygen quantum yield, the
absorbance at excitation wavelength, the slope of the absorbance of
DPBF at 414 nm changing over time, and fractive index of the solvent
used for measurement, respectively.
Electrochemistry
eluent to give compound
7 (74 mg, yield 26%). UV-vis (CH2Cl2),
8 | J. Name., 2012, 00, 1-3
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Journal of Materials Chemistry C
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There are no conflicts to declare.
The cyclic voltammograms were recorded utilizing a PlamStat3+
connected to a computer using PSTrace 5.5 software. A three-
electrode system was used consisting of mini glassy carbon electrode
as a working electrode, a platinum wire as a counter electrode, and
an Ag/AgCl as a reference electrode. The CV measurements were
performed in DCM solutions, 0.1 M in tetrabutylammonium
perchlorate, and 1 mM substrate at ambient temperature with 100
mV/s scan rates.
View Article Online
DOI: 10.1039/D0TC03490H
Acknowledgements
Financially supported by National Natural Science Foundation
of China (21301092, 21961039), Natural Science Foundation of
Jiangsu Province, P. R. China (No. BK20151513). J. Z. thanks
NSFC (21673031, 21761142005, and 21911530095) for financial
supports.
Nanosecond transient absorption spectroscopy
The nanosecond time-resolved transient absorption spectra
were measured on LP980 laser flash photolysis spectrometer
(Edinburgh Instruments, UK), and the signal was digitized with a
Tektronix TDS 3012B oscilloscope. The compound solutions
were excited with an OPOLette 355II+UV nanosecond pulsed
laser, the typical pulse length is 7 ns and the wavelength is
tunable within the range 210−2400 nm (OPOTEK, USA). The
lifetimes were recorded with the LP900 software by monitoring
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
std 





A
I
std
 sam  sam 
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were calculated according to equation eq 4. Where , A, I and
represents the quantum yield, the absorbance at laser
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Conflicts of interest
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Page 12 of 13
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