Mesogenic complementary absorbing dyads based on porphyrin and perylene units

Article abstract of DOI:10.1142/S1088424618500165

Five novel dyads, consisting of a tetraphenylporphyrine unit connected to a perylene monoimide diester unit via a flexible bridge-CONH-(CH2)n-(n = 4, 6, 8, 10 and 12), have been synthesized. Their structures were characterized by 13C and 1H nuclear magnet

Full text of DOI:10.1142/S1088424618500165

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2018; 22: 1–12
DOI: 10.1142/S1088424618500165
Published at http://www.worldscinet.com/jpp/
Mesogenic complementary absorbing dyads based
on porphyrin and perylene units
Xiangfei Konga, Hongkang Gonga, Shengping Daia, WeiYaoa, Linping Mu*b,
a,c
a
Shufen Zhang and Guixia Wang*
a College of Chemistry and Bioengineering, Guangxi Key Laboratory of Electrochemical and Magnetochemical
Functional Materials, Guilin University of Technology, Jian’gan Road No. 12, Guilin 541006, China
bSchool of Physics and Information Engineering, Shanxi Normal University, Gongyuan Avenue No. 1,
Linfen 041004, China.
cState Key Laboratory of Fine Chemicals, Dalian University of Technology, Linggong Road No. 2,
Dalian 116024, China
Dedicated to Professor Kazuchika Ohta on the occasion of his retirement
Received 5 December 2017
Accepted 20 December 2017
ABSTRACT: Five novel dyads, consisting of a tetraphenylporphyrine unit connected to a perylene
monoimide diester unit via a flexible bridge -CONH-(CH2)n- (n = 4, 6, 8, 10 and 12), have been synthe-
1
sized. Their structures were characterized by 13C and H nuclear magnetic resonance spectroscopy,
infrared spectroscopy, mass spectrometry and elemental analysis. The UV-vis absorption spectra revealed
these dyads have broad optical absorption in the ultraviolet and visible regions due to the complementary
absorption of the two units. The differential scanning calorimetry traces and polarized optical microscopy
textures showed all these dyads have columnar liquid crystal phases. Cyclic voltammetry revealed the
highest occupied molecular orbitals of the dyads located on the porphyrin units, and the lowest unoccupied
molecular orbitals located on the perylene units. In addition, these results were in agreement with that of
the theoretical modeling. When excited at 423 or 473 nm, the photoluminescent emission spectra showed
that the degree of fluorescence quenching of porphyrin units increased as the spacers became shorter. This
quenching was ascribed to intramolecular photoinduced electron transfer, which also induced the dyad
molecules to form the charge-separated states. The charge-separated molecules were further confirmed
by the photocurrent response curves. These behaviors of broad absorption of the ultraviolet-visible light,
yielding the charge-separated states of the molecules when excited and the formation of columnar liquid
crystal phase made these dyads candidates for single-component photovoltaic active materials.
KEYWORDS: porphyrin, perylene, discotic liquid crystal, dyad, photoinduced electron transfer.
because of their easily tunable molecular energy levels
INTRODUCTION
and excellent optical absorption properties [8, 9].
Organic solar cells (OSCs), featuring solution
Recently [10], more than 13% PCE was obtained by
processing, light weight and mechanical flexibility,
have attracted immense attention in the past decades
blending a fluorinated p-conjugated polymer with a
fluorinated fullerene-free small-molecule acceptor. In
[1–4]. At present, the state-of-the-art power conversion
spite of these remarkable performances, the realization of
efficiency (PCE) for fullerene-based bulk heterojunction
solution-processed BHJ solar cells still poses a number of
(BHJ) OSCs achieved 11–12% [5–7]. In recent years,
problems related to both the nature of the active materials
non-fullerene acceptors have attracted much attention
and the fabrication process [11]. For example, the fine-
control of phase separation and achieving high charge-
*Correspondence to: Guixia Wang, email: 2010033@glut.edu.
carrier mobility in active layers are still very difficult
with BHJ solar cells [2, 12, 13].
cn, tel.: +86 0773-8991-547, fax: +86 0773-8991-547; Linping
Mu, email: mulinping6266@163.com.
Copyright © 2018 World Scientific Publishing Company

2
X. KONG ET AL.
As another interesting strategy, electron donor–
acceptor dyad, triad, multiad and block copolymer
molecules or all-in-one molecules where the electron
donor (D) and acceptor (A) units are covalently linked
in a single molecule have been reported for their
potential as photovoltaic materials [12, 14–19]. These
single-component photovoltaic materials possess multi-
functions such as light harvesting, exciton dissociation
and electron and hole transport. Moreover, several major
advantages, such as a considerable simplification of
device fabrication, stabilization of the morphology of the
active material, and efficient (or fast) charge separation
can be expected in the single-component OSCs [11].
At present, the PCE for single-component OSCs has
surpassed 2% [12, 15, 17], which is lower than that of
BHJ solar cells. This is because the design of electron
donor–acceptor molecules for efficient single-component
OSCs is in fact difficult. Some important prerequisites for
solar cell applications, such as strong and broad optical
absorption, the energy level matching of the donor and
acceptor units, the prevention of charge recombination
and the efficient transport of the separated charges to the
electrodes, need to be considered and balanced [11].
Wasielewski proposed that the ideal functional organic
materials used in solar cells should have electron donor
and acceptor building blocks covalently attached in a
single molecule, as well as the ordered arrangement of
these building blocks in the solid state [13]. So far, the
first aspect has been investigated as conventional single-
component photovoltaic materials, while the second one
is still a challenge and makes slow progress. However,
the use of self-assembly strategy offers the opportunity
to achieve the ordered structure and improved charge
carrier mobility in the solid state [20, 21].
aliphatic chains, normally through ether, thioether, or
ester bonds peripherally attached to the cores [23–25].
The majority of DLCs are thermotropic liquid crystals
and have a strong tendency for columnar mesophase
formation. Since there are strong p–p interactions
between adjacent cores within the same column, the
carrier mobility is up to 1 cm V s along the columnar
axes [26, 27]. In addition, the peripheral side chains act as
insulating layers, and the charge-carrier mobility is low
in the direction perpendicular to the molecular column.
Thus, the DLC materials exhibiting ordered columnar
phases have application potential as one-dimensional
charge carrier transport systems [28]. So far, the 4–8%
PCE of bilayer solar cells and BHJ solar cells using DLC
materials have been achieved [22].
The dyad, triad and multiad DLCs, containing D and
A units and forming columnar phases, are an emerging
single-component photovoltaic material. Since the
so-called p–n heterojunction exists at the molecular
level, these D–A DLCs possess fast intramolecular
photoinduced electron transfer and form charge
separated states [29–33]. Some D–A DLCs yield dual
pathways along molecular columns to transfer electrons
and holes [34, 35]. At present, the discogens used in these
D–A DLCs are limited in triphenylene, anthraquinone,
perylene and BODIPY derivatives [36–42].
To use a wider range of the solar spectrum, dyads
based on porphyrin and perylene units were designed in
this work. Porphyrins have flat heterocyclic structure
and a delocalized p-electron system, and are excellent
light-harvesting compounds [43]. Prophyrin based
compounds have attracted great interest in the fields
of photodynamic therapy [44, 45], dye-sensitized [46,
47] and BHJ solar cells [48, 49]. While the perylene
derivatives, possessing excellent photochemical and
thermal stability, high fluorescence quantum yield,
and multiple positions for chemical modification,
were attractive candidate materials for OLEDs [50,
51] and OSCs [52–54], and several others. Herein,
2
-1 -1
.
.
Calamitic and discotic liquid crystals (DLCs),
featuring long exciton diffusion length and high charge-
carrier mobility, have been considered as a new generation
of organic photovoltaics [22]. The conventional DLC
molecules comprise a planar rigid core and several
OC12H25
O
N
O
OC6H13
HN
O
NH
N
N
O
O
n
C12H25
O
HN
OC6H13
TPP-Cn-PIE
n = 4, 6, 8, 10 and 12
OC12H25
Fig. 1. Molecular structures of the dyads TPP-Cn-PIE (n = 4, 6, 8, 10 and 12)
Copyright © 2018 World Scientific Publishing Company
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MESOGENIC COMPLEMENTARY ABSORBING DYADS BASED ON PORPHYRIN AND PERYLENE UNITS
3
O
O
O
O
O
OC6H13
C6H13
O
OC6H13
the dyads consisting of a tetraphenylporphyrin unit
(absorption in the purple and yellow regimes) which
was covalently linked to a perylene monoimide diester
(PIE) unit (absorption in the green regime) were
synthesized. The molecular structures of the dyads
are shown in Fig. 1, denoted as TPP-Cn-PIE (n = 4,
6, 8, 10 and 12). The experimental results revealed
that these dyads have broad optical absorption in the
ultraviolent and visible region, and columnar liquid
crystal phases as well.
OO
C6H13
O
(ii)
(i)
C6H13
O
OO OC6H13
2
O
O
O
O
3
O
O
1
H
N
OC12H25
OH
OHC
COOCH3
and
6
7
(iii)
RESULTS AND DISCUSSION
(iv)
O
O
Synthesis
4
5
The synthetic routes are shown in Scheme 1.
Tetrahexyl-perylene-tetracarbonylate (2) [55] and
perylene-mono-anhydride-diester 3 [56] were synthe-
sized in excellent yields according to the reports in
the literature. Long chain aromatic aldehyde 5 [57]
was prepared in quantitative yield, with no previous
protection of the aldehyde moiety. The preparation of the
porphyrin ester (8, TPPE) [58] was the key step towards
asymmetric porphyrin derivative synthesis, which was
obtained via the well-known Adler–Longo methodology
[59]. The primary amine derivatives 9–13 were prepared
by aminolysis reaction of 8 [60]. Since compounds 9–13
in solution were sensitive to air, they, without further
purification, were condensed with 3 to give these dyads.
In addition, the reference compound N-hexyl-perylene
monoimide dihexyl esters (PIE3) was synthesized
according to the previous report [33].
OC12H25
NH
N
OCH3
O
(v)
C12H25
O
HN
N
8
OC12H25
OC12H25
More specifically, the first step was the hydrolysis
of perylene-3, 4, 9, 10-tetracarboxylic dianhydride
(1) in basic aqueous solution to prepare the potassium
perylene-3, 4, 9, 10-tetracarboxylate, then converted
to 2 via an efficient phase-transfer catalysis method
with methyl-trioctyl-ammonium chloride as a catalyst.
Dihexyl-perylene-3, 4-anhydride-9, 10-dicarboxylate (3)
was obtained as precipitate through acidic hydrolysis of
2 at one side in the mixed solvents of n-heptane and
toluene. In the second step, 5 was prepared in quantitative
yield via the alkylation of 4-hydroxybenzaldehyde (4) in
the presence of anhydrous potassium carbonate, in DMF
at 80°C. 8 was prepared through the condensation reac-
tion between 5, methyl 4-formylbenzoate (6) and pyrrole
(7) in the mixed solvent of xylol and 3-nitrobenzoic acid
at 140°C. Then 8 underwent an aminolysis reaction
with excess alkane-a, w-diamines, which also acted
as solvents, to give 9–13. The dyads were synthesized
by the imidization reaction between 3 and the primary
amine derivatives in imidazole at 130°C, as dark red
solids. The yields of the imidization reaction were
33–40%, which were attributed to the instability of the
compounds 9–13.
NH
N
NH
O
NH2
n
C12H25
O
HN
N
9
n= 4
10 n= 6
11 n= 8
12 n= 10
13 n= 12
OC12H25
OC6H13
O
O
O
O
O
3
OC6H13
TPP-Cn-PIE
( n = 4, 6, 8, 10 and 12)
(vi)
Scheme 1. Synthesis of dyads TPP-Cn-PIE (n = 4, 6, 8,
10 and 12). Reagents and conditions: (i) a. KOH, H2O,
75 °C, 1.5 h, b. HCl, pH = 8–9, C6H13Br, methyl trioctyl
ammonium chloride, reflux, 6 h, 57%; (ii) toluene/heptane =
1/5, p-toluenesulfonic acid, 95 °C, 5 h, 79%; (iii) C12H25Br,
K2CO3, DMF, 80 °C, 12 h, 98%; (iv) xylol, 3-nitrobenzoic
acid, 140 °C, 3.5 h, 28%; (v) NH2(CH2)nNH2, (n = 2, 4, 6, 8,
10 and 12), 100 °C, 22–48 h, 82–88%; (vi) imidazole, 130 °C,
5 h, 33–40%
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X. KONG ET AL.
Fig. 2. Optical texture of TPP-C12-PIE (a, on heating at 117°C) and POM microphotographs of TPP-C12-PIE (b), TPP-C10-
PIE (c), TPP-C8-PIE (d), TPP-C6-PIE (e), TPP-C4-PIE (f) (observed in the cooling processes from the isotropic liquid at room
temperature after applying mechanical stress, the scale bars are 50 μm, crossed polarizers)
Phase behaviors and potential in self-organization
when squeezed at room temperature. When heated, the
red fluid started to flow at 90°C with birefringence,
which was maintained until 105°C. Upon cooling, the
isotropic liquid cannot flow at 70°C, the birefringence
did not restore until room temperature. After applying
mechanical stress, the birefringent phenomenon can be
visualized expressly (see Fig. 2c).
In the first heating circle, TPP-C8-PIE showed
three endothermic transitions which peaked at 78, 105
and 119°C. During the first cooling circle, one broad
exothermic transition peaked at 87°C (see Table 1 and
Fig. S3). Under microscopic observation, the birefringent
waxy solid was deformed when pressed at room
temperature. When heated the red fluid started to flow at
105°C with birefringence, which disappeared at 123°C
with continued heating. Upon cooling, the isotropic liquid
cannot run at 80°C, and the birefringence did not appear
until room temperature. When squeezed, the birefringent
phenomenon can be seen clearly (see Fig. 2d).
DSC curves showed two endothermic peaks at 78 and
111°C in the heating cycle for TPP-C6-PIE, and one
exothermic peak at 99°C during the first cooling (see
Table 1 and Fig. S4). Under microscopic observation, the
birefringent waxy solid was deformed when squeezed at
room temperature. When heated, the red fluid started to
flow at 110°C with birefringence, and it disappeared at
125°C. When cooled, the isotropic liquid cannot run at
92°C and the birefringence was not present until room
temperature. When pressed, the birefringent phenomenon
could be readily observed (see Fig. 2e).
Phase behaviors of the dyads were investigated by
polarized optical microscopy (POM, see Fig. 2) and the
differential scanning calorimetry (DSC, see Fig. 3 and
Figs S1–S5 in the supplementary information). Peak
transition temperatures along with the associated enthalpy
changes (DH) are listed in Table 1. As shown in Fig. 3 and
Fig. S1, TPP-C12-PIE showed two endothermic transitions
and peaked at 68 and 114°C in the first heating cycle, and
one exothermic peak at 68°C during the first cooling circle.
Under microscopic observation, the birefringent waxy
solid was deformed when squeezed at room temperature.
When heated, the birefringent fluid started to flow at
100°C, and the birefringent phenomenon disappeared at
128°C. The optical texture observed at 117°C showed
it had a columnar liquid crystal phase (see Fig. 2a).
When cooled, the isotropic liquid cannot flow at 60°C.
In addition, the weak birefringent phenomenon resorted
at room temperature. After applying mechanical stress,
the birefringent phenomenon can be seen clearly (see
Fig. 2b). It is believed that when cooled from the isotropic
liquid, the molecules of the dyad self-assemble and arrange
in face-on alignment on the slides (in which the molecular
columns are perpendicular to the surface of the slide).
During the first heating run, TPP-C10-PIE showed one
endothermic transition which peaked at 93°C. During the
first cooling circle, one broad exothermic peak occurred
at 74°C (see Table 1 and Fig. S2). Under microscopic
observation, the birefringent waxy solid was deformed
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MESOGENIC COMPLEMENTARY ABSORBING DYADS BASED ON PORPHYRIN AND PERYLENE UNITS
5
-1
.
reference electrode. The scan rate was 50 mV s . For all
CV measurements, the ferrocene/ferrocenium (Fc/Fc+)
redox couples were used for calibration [61].
The cyclic voltammograms of TPPE, PIE3 and TPP-
C10-PIE are shown in Fig. 4. The HOMO energy values
of these compounds were obtained from the potential
values corresponding to the onsets of the first oxidation
waves (denoted as Eox (1)). The Eox (1) of TPPE,
PIE3 and TPP-C10-PIE were 1.24, 1.75 and 1.15 V,
respectively. In addition, the potential value of the dyad
corresponding to the onset of the second oxidation wave
(denoted by Eox (2)) was 1.59 V. Analysis of these data
showed that the first and second oxidation waves of the
dyads can be assigned to the oxidation reactions of the
porphyrin unit and the perylene unit, respectively.
Calibrated with the Fc/Fc+ redox system, the HOMO
energy value of each compound was estimated by the
equation HOMO (eV) = -[e (Eox (1) -E (Fc/Fc+)) + 4.8]
[30]. Thus, the HOMO values of TPPE, PIE3 and TPP-
C10-PIE were -5.50, -5.95 and -5.51 eV, respectively.
The LUMO value of a compound can be estimated
from the optical band gap (denoted as Eg) and the
HOMO value by the equation LUMO = HOMO + Eg
[30]. The Eg was inferred from the onset of the longest
wavelength absorption band. The Eg values of TPPE
and PIE3, inferred from the onsets of the absorption
spectra (Fig. 6), were 1.86 and 2.30 eV, respectively.
Thus, the LUMO values of TPPE and PIE3 were -3.64
and -3.65 eV, respectively. As we know, the LUMO of
a dyad linked by a flexible spacer is coincident with
the lower one of the two units [30]. Thus, the HOMO
value (-5.95 eV), corresponding to Eox (2), and Eg (2.30
eV) of perylene unit should be used in the equation
LUMO = HOMO + Eg, and the LUMO value of TPP-
C10-PIE is -3.65 eV. In this way, the Eg of TPP-C10-PIE
equals 1.86 eV.
Fig. 3. DSC traces of TPP-C12-PIE (The downward peaks are
characteristic of endothermic events; first heating and cooling
-1
.
cycle, peak temperatures labeled, at the scan rate of 10°C min )
TPP-C4-PIE showed two endothermic transitions and
peaked at 78 and 114°C in the first heating cycle, and one
exothermic peak at 104°C during the first cooling cycle
(see Table 1 and Fig. S5). Under microscopic observation,
the birefringent waxy solid was deformed when pressed
at room temperature. When heated, the birefringent fluid
cannot run until 115°C, and the birefringent phenomenon
disappeared at 130°C. When cooled, the isotropic liquid
cannot flow at 99°C and the birefringence did not resort
until room temperature. When pushed, the birefringent
phenomenon can be seen clearly (see Fig. 2f).
Electrochemical behaviors and HOMO/LUMO
energy levels
The electrochemical behaviors of the reference
compounds TPPE and PIE3, and the dyads TPP-C10-
PIE were studied by cyclic voltammetry (CV) in dry
acetonitrile with 0.1 mol L tetrabutylammonium hexa-
The electronic structures of the cores of TPP-C10-PIE
were modeled using the Gaussian 16 suite of programs.
Since the side chains have little effect on the HOMO and
LUMO values of DLCs [62], the alkyl chains were all
replaced by methyl groups in the computer simulations
to reduce the computational load. Full geometry
optimization of the dyad were performed at the density
-1
.
fluorophosphate (TBAPF6) as the supporting electrolyte.
The experiments were performed at room temperature,
using a standard three-electrode cell with a glass carbon
electrode as the working electrode, a platinum wire as
the counter electrode and an Ag/AgCl electrode as the
Table 1. Phase behaviors of TPP-Cn-PIE (n = 4, 6, 8, 10 and 12). Phase transition temperatures (peak, °C) and associated
-1
-1
.
.
enthalpy changes (J g , in parentheses) determined by DSC at the scan rate 10°C min , under N2
-1
-1
.
.
Compounds
First heating scan, temperatures (°C) (DH (J g )) First cooling scan, temperatures (°C) (DH (J g ))
TPP-C12-PIE Col1a 68 (0.70) Col2a 114 (15.76) Ia
Ia 68 (0.67) Cola
I 74 (0.52) Col
I 87 (0.38) Col
I 99 (0.32) Col
I 104 (0.32) Col
TPP-C10-PIE
TPP-C8-PIE
TPP-C6-PIE
TPP-C4-PIE
Col1 93 (6.71) I
Col1 78 (0.16) Col2 105 (0.35) Col3a 119 (1.08) I
Col1 78 (1.84) Col2 111 (0.38) I
Col1 78 (0.52) Col2 114 (0.12) I
a Col1, Col2, Col3 and Col: columnar liquid crystal phase; I: isotropic liquid.
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X. KONG ET AL.
Fig. 4. Cyclic voltammograms of compounds TPPE, PIE3
and TPP-C10-PIE at room temperature (drop casted films,
-1
.
0.1 mol L in acetonitrile solution of TBAPF6, at the scan
-1
.
rate of 50 mV s ). In order to facilitate the observation, the
curves of PIE3 and TPP-C10-PIE moved up 0.3 and 0.45 mA,
respectively
Fig. 5. Optimized geometric structure of TPP-C10-PIE in DCM
and its frontier orbitals calculated by density functional theory
(DFT) at the B3LYP/6-31G level
functional theory (DFT) level using Becke’s three-
parameter B3LYP exchange functional and the 6-31G
basis set. The geometry of the dyad was optimized in
dichloromethane (DCM), and its isosurfaces of the
frontier molecular orbital are illustrated in Fig. 5. It can
be seen that the dyad molecule tends to exist in extended
conformations in dilute DCM solution, and the HOMO
and LUMO orbitals of the dyad are located on the
porphyrin and perylene units, respectively. The HOMO,
LUMO and Eg values were predicated to be -5.12, -3.35
and 1.77 eV, respectively, which matched the measured
values.
Steady-state spectroscopy
UV-vis absorption spectra. UV-vis absorption spectra
of the TPPE, PIE3, the mixture of TPPE and PIE3
(in the molar ratio of 1:1), and the dyads TPP-Cn-PIE
(n = 4, 6, 8, 10 and 12) were studied in DCM solutions
-6
-3
.
(5 × 10 mol dm ) (Fig. 6). PIE3 has optical absorption
from 250 to 540 nm. In the ultraviolet region, its absor-
ption maximum is at 263 nm, and the peak optical density
corresponds to an extinction coefficient (e) of 4.56 × 104
Fig. 6. UV-vis absorption spectra of TPPE, PIE3, the mixture
of TPPE and PIE3 (in the molar ratio of 1:1), and TPP-Cn-
PIE (n = 4, 6, 8, 10 and 12) in DCM, c = 5 × 10 mol dm . In
order to facilitate the observation, the curves of the mixture,
TPP-C4-PIE, TPP-C6-PIE, TPP-C8-PIE, TPP-C10-PIE and
TPP-C12-PIE were successively moved up 0.05 unit
-6
-3
.
-1
-1
.
.
L mol cm , belonging to the transition of n–p* of
C=O groups [33]. In the visible region, it has a maximum
4
-1
-1
.
.
absorption at 507 nm (e = 5.48 × 10 L mol cm ) with
two vibronic bands at 475 and 450 nm, correlated to the
p–p* electron transitions. TPPE shows characteristic
I–IV Q bands (652, 596, 557 and 517 nm) and one strong
is a superimposition of the two monomeric spectra. This
shows that there is no charge transfer between the TPPE
and PIE3 molecules in the ground states in dilute DCM
solution. The absorption spectra of the dyads are almost
identical to that of the mixture of TPPE and PIE3 (in the
molar ratio of 1:1), showing that in the ground states the
electronic coupling between the two units of a dyad is
5
-1
-1
.
.
Soret band (422 nm, e = 4.88 × 10 L mol cm ),
belonging to the p–p* electron transitions of the
porphyrin ring [63].
The absorption spectrum of the mixture of TPPE and
PIE3 (in the molar ratio of 1:1), retained the Soret and
I–IV Q bands of TPPE and the vibronic bands of PIE3,
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MESOGENIC COMPLEMENTARY ABSORBING DYADS BASED ON PORPHYRIN AND PERYLENE UNITS
7
weak. In summary, the absorption spectra of the
dyads cover the ultraviolet and visible regions
of the solar spectrum due to the complementary
absorption of the porphyrin and perylene units.
Photoluminescent emission spectra. Photo-
luminescent emission spectra of the dyads
were measured in DCM solutions (c = 5 × 10-6
-3
.
mol dm ) at 423 and 473 nm, which correspond
Fig. 8. Schematic representation of the photoinduced electron transfer
of TPP-C10-PIE (lex = 423 nm, a dashed arrow indicates the two energy
levels involving one transition or transfer of an electron)
to the optical absorptions of the Soret band
of the porphyrin unit and the perylene unit,
respectively. As a comparison, the emission of
the reference compounds TPPE and PIE3 were
which are responsible for the fluorescence quenching of
also measured.
the porphyrin units.
Excited at 423 nm, PIE3 has characteristic fluores-
cence emissions between 490 and 700 nm, with one peak
at 528 nm and two shoulders at 559 and 622 nm (see
Fig. 7). The fluorescence emissions of TPPE is between
630 and 780 nm, with the peak at 662 nm and one
shoulder at 728 nm. The peak intensity of TPPE is
about one fifth of that of PIE3. Compared with TPPE,
the spectra profiles of TPP-Cn-PIE (n = 4, 6, 8, 10 and
12) are very similar. The fluorescence emission of the
perylene units of the dyads is completely quenched. This
is attributed to the Förster and Dexter type energy transfer
from the perylene units to the porphyrin units, since the
fluorescence emission region of the perylene unit (490–
700 nm) is overlapped with the Q-bands of porphyrin
(480–680 nm), and the lengths of the bridges of the
dyads are less than 10 angstroms. Thus, the porphyrin
units acquiring energy from the perylene units should
have a stronger fluorescence emission than that of TPPE.
However, the emission intensity of the highest peaks of
the dyads decrease as compared with that of TPPE, and
a further decrease is found as the flexible spacers get
shorter. This implies there are additional electron transfer
processes between the prophyrin and perylene units,
The fluorescence quenching of the porphyrin units
can be explained by the photoinduced electron transfer
theory [64]. The electron-rich porphyrin units and the
electron-deficient perylene units act as the electron D and
A, and were looked at as entities that could be studied
separately. To simplify these processes, the HOMO
and LUMO values of the D and A units are assumed
to be fixed. In the case of TPP-C10-PIE, the energetic
positions of the HOMO and LUMO energy levels are
shown schematically in Fig. 8.
When the D unit was excited, the electron transfer
processes of the dyad were depicted in Fig. 8. Before
excitation, the dyad molecule was in the ground state
(indicated by A–D). When the D unit was excited
(represented by Ex), an electron transitioned from the
HOMO to the LUMO to give a molecule with the D unit
in the excited state (denoted by A–D*). Since the LUMO
level of the D unit was higher than that of the A unit,
and the core of the A unit was deficient in electrons, the
electron in the LUMO of the D transferred to A, yielding
a molecule in charge transfer state (denoted by A-·–
D+·). This was a photoinduced electron transfer process
(represented by PET). In the end, the electron on the
LUMO level of the A unit transferred to the HOMO level
of the D unit, and then two units returned to the original
ground state. This process was a charge recombination
process (expressed by CR). In the above processes, the
PET was a key step leading to fluorescence quenching.
According to the theory of photoinduced electron transfer,
the electron transfer rate constant decays exponentially
with the distance between the D and A units [64]. Thus,
the shorter the bridges are, the stronger the fluorescence
quenching degrees of the D units are.
Excited at 473 nm, the profiles of fluorescence
emission spectra of PIE3 and TPPE were similar to that
when they were excited at 423 nm, respectively (Fig. 9),
while the fluorescence emission of the featured dyads has
the characteristics of both PIE3 and TPPE. Since there
were the Förster and Dexter type energy transfer from
the perylene units to the porphyrin units, the fluorescence
emission of the perylene units of the dyads was quenched,
and the emission of the porphyrin units was enhanced. It
also can be seen that the peak intensities of the porphyrin
Fig. 7. Fluorescence emission spectra of TPPE, PIE3
and TPP-Cn-PIE (n = 4, 6, 8, 10 and 12) in DCM (c = 5 ×
-6
-3
.
10 mol dm , lex = 423 nm, the intensity of PIE3 plotted here
was a quarter of its original value)
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 7–12

8
X. KONG ET AL.
When the TPP-C10-PIE film was irradiated with
white light, the molecules in charge-separated state,
TPP+·-C10-PIE-·, were yielded due to the intramolecular
photoinducedelectrontransfer(seeFig. 8).Thenegatively
charged perylene unit gave electrons to the conduction
band of ITO, which resulted in the anodic photocurrent.
EXPERIMENTAL
Materials
All reagents and solvents were fromAladdin Industrial
Corporation, Macklin Inc., XiLong Chemical and FuYu
Chemical. All were analytically pure and used without
further purification if not specified.
Fig. 9. Fluorescence emission spectra of TPPE, PIE3 and
TPP-Cn-PIE (n = 4, 6, 8, 10 and 12) in DCM (c = 5 × 10-6
-3
.
mol dm , lex = 473 nm. The intensity of PIE3 plotted here was
Characterization and instrumentation
five percent of its original value)
IR was performed on a VECTOR 22 FT-IR spectro-
1
meter (KBr tablet). H NMR spectra were recorded on
a Bruker spectrometer (500 MHz). Mass spectra were
obtained on an Agilent ESI 6400 mass spectrometer. EA
was recorded on a Thermo Flash EA-1112 instrument.
DSC experiments were carried out on a ThermalAnalysis
DSC-Q100instrument.Themesomorphicpropertieswere
evaluated by a polarized optical microscopy instrument
(Olympus THMS600) provided with a heating stage
(Linkam THMSE 600). CV and photocurrent curves
were performed on a Shanghai Chen Hua CHI760E
electrochemical workstation. Geometry optimization of
the dyad was performed by Gaussian 16 program package.
UV-vis absorption spectra were recorded on a Shimadzu
UV-2450 spectrometer. Fluorescence emissions were
performed on a HITACHI F-4600 instrument.
Fig. 10. Photocurrent curve of TPP-C10-PIE film polarized at
+0.10 V and irradiated with intermittent white light (counter
electrode: platinum wire; reference electrode: Ag/AgCl
electrode; working electrode: ITO glass coated with TPP-
Synthesis
Synthesis of tetrahexyl perylene-3,4,9,10-tetracar-
boxylate (2). The solution of 1 (0.95 g, 2.42 mmol)
and potassium hydroxide (2.63 g, 46.9 mmol) in water
(300 mL) was filtered after stirring at 70°C for 1.5 h. The
filtrate was acidified with HCl (ca. 1 mol L ) until the
C10-PIE; supporting electrolyte: KCl aqueous solution, c =
-3
.
0.1 mol dm )
-1
.
pH was 8–9. Then 1-bromohexane (4.2 g, 25.2 mmol)
and methyl-trioctyl-ammonium chloride (1 g, 0.2 mmol)
were added to the solution. The reaction mixture was
then refluxed for 6 h under vigorous stirring, then cooled
to room temperature, and filtered. The filter cake was
washed with ethanol (35 mL) three times to give 2 as a
units decreased as the flexible linkers got shorter. The
fluorescence quenching of the porphyrin units is also
attributed to the photoinduced electron transfer, just as
that they were quenched at 423 nm.
Photocurrent phenomena
1
yellow solid. Yield 1.05 g (57%). H NMR (500 MHz;
The photocurrent generation of TPP-C10-PIE film,
deposited on an indium tin oxide (ITO) glass electrode,
was tested using a standard three-electrode cell. The film
CDCl3; Me4Si): dH, ppm 0.91 (12H, t, -CH3), 1.37–1.35
(16H, m, -CH2-), 1.48–1.42 (8H, m, -CH2-), 1.83–1.78
(8H, m, -O-CH2-CH2-), 4.33 (8H, t, -O-CH2-), 7.96–7.91
(4H, m, Ar-H), 8.13–8.06 (4H, m, Ar-H).
Synthesis of dihexyl-perylene-3,4-anhydride-9,10-
dicarboxylate (3). 2 (4 g, 5.23 mmol) was added to
the mixed solvent of toluene (3.0 mL) and heptane (15
mL). When heated to 80°C the mixture became clear.
on the working electrode was fabricated by the drop-
-2
.
casting method. Using 63.2 mW cm intermittent white
light irradiation and applying a voltage of +0.1 V to the
working electrode, a rapid anodic photocurrent response
was observed (Fig. 10).
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 8–12

MESOGENIC COMPLEMENTARY ABSORBING DYADS BASED ON PORPHYRIN AND PERYLENE UNITS
9
A red slurry was obtained after the reaction mixture
10/1–5/1 v/v), to give 9 as a purple solid. However,
the TLC showed that part of 9 had decomposed in
this process. Thus, it was condensed with 3 as soon as
possible to give TPP-C4-PIE.
reacted with p-toluene sulfonic acid (1.04 g, 5.47 mmol)
at 95°C for 5 h. After cooling to room temperature,
the red solid was collected by filtration. The wet filter
cake was recrystallized twice from DCM (24 mL) and
methanol (40 mL), to give 3 as a red solid. Yield 2.39 g
Synthesis of N-(6-aminohexyl)-4-(10,15,20-tris(4-
(dodecyloxy)phenyl)porphyrin-5-yl)benzamide(10).The
same procedure as for 9 with hexane-1,6-diamine (3 g).
The crude product as a purple solid without further
purification was condensed with 3 to yield TPP-C6-PIE.
Synthesis of N-(8-aminooctyl)-4-(10,15,20-tris(4-
(dodecyloxy)phenyl)porphyrin-5-yl)benzamide(11).The
same procedure as for 9 with octane-1,8-diamine (3 g).
The crude product as a purple solid without further
purification was condensed with 3 to yield TPP-C8-PIE.
Synthesis of N-(10-aminodecyl)-4-(10,15,20-tris(4-
(dodecyloxy)phenyl)porphyrin-5-yl)benzamide (12).
The same procedure as for 9 with decane-1,10-diamine
(3 g). The crude product as a purple solid without further
purification was condensed with 3 to yield TPP-C10-PIE.
Synthesis of N-(12-aminododecyl)-4-(10,15,20-tris
(4-(dodecyloxy)phenyl)porphyrin-5-yl)benzamide (13).
The same procedure as for 9 with dodecane-1,12-diamine
(3 g). The crude product as a purple solid without further
purification was condensed with 3 to yield TPP-C12-PIE.
Synthesis of TPP-C4-PIE. Under nitrogen, the mixture
of 9 (0.63 g, 0.53 mmol) and 3 (0.37 g, 0.63 mmol) in
imidazole (10 g) was stirred at 130°C for 5 h, allowed
to cool to room temperature and then diluted with hot
H2O (20 mL). The red solid was collected by filtration,
and purified by column chromatography (silica gel,
DCM/ethyl acetate, 15/1–5/1 v/v), to give the title
compound as a red solid.Yield 0.26 g (34%). Anal. calcd.
for C121H144N6O10: C, 78.88; H, 7.88; N, 4.56, found:
C, 78.69; H, 8.01; N, 4.46. UV-vis (DCM): lmax, nm
(log e) 263 (4.72), 422 (5.71), 475 (4.60), 506 (4.76),
555 (4.08), 593 (3.75), 651 (3.77). IR (KBr) nmax, cm-1
3445 (N–H), 2920–2853 (aliphatic-CH), 1770, 1701,
1651, 1597, 1507, 1461, 1358, 1296, 1246, 1165, 1075,
1
(79%). H NMR (500 MHz; CDCl3; Me4Si): dH, ppm
0.91 (6H, t, -CH3), 1.38–1.34 (8H, m, -CH2-), 1.49–1.44
(4H, m, -CH2-), 1.84–1.78 (4H, m, -O-CH2-CH2-), 4.35
(4H, t, -O-CH2-), 8.12 (2H, d, Ar-H), 8.48 (4H, t, Ar-H),
8.62 (2H, d, Ar-H).
Synthesis of 4-(dodecyloxy)benzaldehyde (5). 4
(2.44 g, 20 mmol), 1-bromododecane (6.72 g, 26.9 mmol)
and anhydried potassium carbonate (5.52 g, 40 mmol)
were added to dried DMF (20 mL). Under nitrogen,
the mixture was stirred at 80°C for 12 h, then cooled
to room temperature and diluted with water (100 mL).
After extraction with DCM (4 × 30 mL), the combined
organic layer was washed with brine (20 mL) and
then dried (Na2SO4). After the solvent was removed at
reduced pressure, the oily product obtained was purified
by column chromatography (silica gel, DCM/petroleum
ether, 1/2 v/v) to give 5 as a yellow oil. Yield 5.75 g
1
(98%). H NMR (500 MHz; CDCl3; Me4Si): dH, ppm
0.88 (3H, t, -CH3), 1.37–1.23 (16H, m, -CH2-),1.49–1.43
(2H, m, -CH2-), 1.83–1.77 (2H, m, -O-CH2-CH2-), 4.04
(2H, t, -O-CH2-),6.99 (2H, d, Ar-H), 7.83 (2H, d, Ar-H),
9.88 (1H, s, -CHO).
Synthesis of methyl 4-(10,15,20-tris(4-(dodecyloxy)
phenyl)porphyrin-5-yl)benzoate(8, TPPE). Onesolution
of 5 (5.88 g, 21 mmol) and 6 (1.19 g, 6.7 mmol) in the
mixture of 3-nitrobenzoic acid (1.85 g, 13.5 mmol) and
xylol (32 ml) was heated to 140°C. The other solution of
pyrrole (1.805 g, 26.9 mmol) in xylol (32 mL) was slowly
added to the first in 0.5 h. The mixture was then stirred at
140°C for another 3.5 h. After evaporation of the xylon
in vacuo, the crude product was purified by column
chromatography (silica gel, DCM/petroleum ether,
1/2–1/1 v/v), then recrystallized from dichloromethane
(10 mL) and methanol (10 mL) to give 8 as a purple
1
959, 798, 732. H NMR (500 MHz; CDCl3; Me4Si): dH,
ppm -2.79 (2H, s, pyrrole-NH), 0.90–0.88 (15H, m,
-CH3), 1.50–1.34 (60H, m, -CH2-), 1.65–1.61 (6H, m,
-CH2-), 1.81–1.75 (4H, m, -CH2-), 2.04–1.91 (10H, m,
-CH2-), 3.79–3.75 (2H, m, -N-CH2-), 4.25–4.20 (6H,
m, -O-CH2-), 4.31 (6H, t, -O-CH2- and -NH-CH2-),
7.03 (1H, t, -CO-NH-), 7.24 (4H, d, Ar-H), 7.26 (2H, s,
Ar-H), 8.03 (2H, d, Ar-H), 8.07 (4H, d, Ar-H), 8.08 (2H,
d, Ar-H), 8.20 (2H, d, Ar-H), 8.26 (2H, d, Ar-H), 8.32
(4H, d, Ar-H), 8.52 (2H, d, Ar-H), 8.76 (2H, d, Ar-H),
8.86 (6H, s, Ar-H). 13C NMR (125 MHz; CDCl3) dC, ppm
14.0, 14.1, 17.8, 22.6, 22.7, 25.5, 25.7, 26.21, 26.24,
26.8, 28.5, 29.38, 29.47, 29.50, 29.53, 29.67, 29.71, 31.5,
31.9, 33.1, 39.6, 65.8, 68.23, 68.26, 112.7, 118.3, 120.0,
120.3, 121.0, 121.2, 122.2, 122.4, 125.4, 128.4, 128.6,
128.8, 128.9, 130.1, 130.5, 130.8, 131.27, 131.33, 131.5,
131.7, 131.8, 133.9, 134.1, 134.2, 134.6, 134.8, 135.5,
135.6, 145.4, 158.9, 159.0, 163.0, 163.2, 167.6, 168.1.
MS (ESI): m/z 1865 (calcd. for [M + Na]+ 1865).
1
solid. Yield 2.28 g (28%). H NMR (500 MHz; CDCl3;
Me4Si): dH, ppm -2.75 (2H, s, pyrrole-NH), 0.90 (9H,
t, -CH3), 1.49–1.31 (48H, m, -CH2-),1.65–1.58 (6H,
m, -CH2-), 2.01–1.94 (6H, m, -CH2-), 4.10 (3H, s,
-COOCH3), 4.23 (6H, t, -O-CH2-), 7.26 (6H, d, Ar-H),
8.10 (6H, d, Ar-H), 8.30 (2H, d, Ar-H), 8.43 (2H, d,
Ar-H), 8.76 (2H, d, Ar-H), 8.88 (6H, d, Ar-H).
SynthesisofN-(4-aminobutyl)-4-(10,15,20-tris(4-(do-
decyloxy)phenyl)porphyrin-5-yl)benzamide (9). Under
nitrogen, the solution of 8 (0.7 g, 0.57 mmol) in butane-
1,4-diamine (3 g) was stirred at 100°C for 22 h, allowed
to cool to room temperature and then diluted with H2O
(30 mL). After extraction with DCM (4 × 15 mL),
the combined organic layers were washed with brine
(15 mL) and then dried (Na2SO4). The solvent was
removed in vacuo. The crude product was purified by
column chromatography (silica gel, DCM/methanol,
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 9–12

10
X. KONG ET AL.
Synthesis of TPP-C6-PIE. The same procedure as
for TPP-C4-PIE with 10 (0.5 g, 0.39 mmol), 3 (0.18 g,
0.32 mmol) and imidazole (5 g), to give the title
compound as a red solid. Yield 0.27 g (40%). Anal. calcd.
for C123H148N6O10: C, 78.98; H, 7.98; N, 4.49, found:
C, 78.97; H, 8.13; N, 4.56. UV-vis (CH2Cl2): lmax, nm
(log e) 263 (4.79), 422 (5.70), 474 (4.60), 506 (4.76),
555 (4.08), 593 (3.74), 650 (3.75). IR (KBr) nmax, cm-1
3383–3320 (N–H), 2932–2854 (aliphatic-CH), 1719,
1698, 1650, 1601, 1511, 1470, 1360, 1296, 1250, 1180,
compound as a red solid.Yield 0.26 g (34%). Anal. calcd.
for C127H156N6O10: C, 79.17; H, 8.16; N, 4.36, Found:
C, 79.07; H, 8.11; N, 4.41. UV-vis (CH2Cl2): lmax, nm
(log e) 263 (4.73), 422 (5.70), 473 (4.58), 505 (4.75), 556
(4.08), 593 (3.74), 651 (3.77). IR (KBr) nmax, cm-1 3426
(N–H), 2922–2852 (aliphatic-CH), 1697, 1650, 1607,
1511, 1469, 1385, 1296, 1248, 1171, 1081, 1026, 798.
1H NMR (500 MHz; CDCl3; Me4Si): dH, ppm -2.84 (2H,
s, pyrrole -NH), 0.92–0.88 (15H, m, -CH3), 1.47–1.31
(70H, m, -CH2-), 1.66–1.62 (8H, m, -CH2-), 1.82–1.76
(8H, m, -CH2-), 2.00–1.93 (6H, m, -CH2-), 3.66–3.62 (2H,
m, -N-CH2-), 4.17 (2H, t, -NH-CH2-), 4.26–4.22 (6H, m,
-O-CH2-), 4.32 (4H, t, -O-CH2-), 6.53 (1H, t, -CO-NH-),
7.28–7.25 (6H, m, Ar-H), 8.02–8.00 (2H, m, Ar-H),
8.09–8.07 (6H, m, Ar-H), 8.15 (2H, d, Ar-H), 8.25–8.19
(4H, m, Ar-H), 8.26 (2H, d, Ar-H), 8.44–8.41 (2H, m,
Ar-H), 8.75 (2H, d, Ar-H), 8.87 (6H, s, Ar-H). 13C NMR
(125 MHz; CDCl3) dC, ppm 14.0, 14.1, 22.6, 22.7, 25.7,
26.2, 27.0, 27.1, 28.0, 28.5, 29.2, 29.3, 29.4, 29.5, 29.7,
31.5, 31.9, 40.4, 40.5, 65.8, 68.3, 112.7, 118.2, 120.0,
120.3, 121.5, 121.8, 122.4, 125.2, 125.5, 128.7, 128.8,
129.1, 130.2, 131.0, 131.7, 131.8, 134.2, 134.3, 134.7,
135.0, 135.59, 135.61, 145.5, 159.0, 163.4, 167.7, 168.2.
MS (ESI): m/z 1949 (calcd. for [M + Na]+ 1949).
1
1081, 966, 842, 801, 737. H NMR (500 MHz; CDCl3;
Me4Si): dH, ppm -2.79 (2H, s, pyrrole-NH), 0.90–0.88
(15H, m, -CH3), 1.46–1.31 (60H, m, -CH2-), 1.69–1.58
(8H, m, -CH2-), 1.89–1.77 (10H, m, -CH2-), 2.00–1.93
(6H, m, -CH2-), 3.66–3.63 (2H, m, -N-CH2-), 4.25–4.20
(8H, m, -O-CH2- and -NH-CH2-), 4.32 (4H, t, -O-CH2-),
6.76 (1H, t, -CO-NH-), 7.23 (4H, d, Ar-H), 7.26 (2H, d,
Ar-H), 8.00 (2H, d, Ar-H), 8.09–9.05 (6H, m, Ar-H), 8.19
(2H, d, Ar-H), 8.27 (6H, d, Ar-H), 8.48 (2H, d, Ar-H), 8.76
(2H, d,Ar-H), 8.85 (6H, s,Ar-H). MS (ESI): m/z1893 (calcd.
for [M + Na]+ 1893).13C NMR (125 MHz; CDCl3) dC, ppm
14.0, 14.1, 22.6, 22.7, 25.7, 26.2, 27.00, 27.02, 27.9, 28.5,
29.2, 29.38, 29.49, 29.53, 29.67, 29.72, 31.5, 31.9, 40.3,
40.5, 65.8, 68.28, 68.30, 112.7, 118.2, 120.0, 120.3, 121.5,
121.7, 122.4, 125.3, 125.5, 128.7, 128.8, 129.0, 130.2,
131.0, 131.7, 131.8, 134.1, 134.2, 134.3, 134.7, 135.0,
135.56, 135.61, 145.4, 158.96, 158.98, 163.3, 167.7, 168.2.
Synthesis of TPP-C8-PIE. The same procedure as
for TPP-C4-PIE with 11 (1.07 g, 0.79 mmol), 3 (0.55 g,
0.95 mmol) and imidazole (10 g), to give the title
compound as a red solid. Yield 0.53 g (38%). Anal. calcd.
for C125H152N6O10: C, 79.08; H, 8.07; N, 4.43, found: C,
79.04; H, 8.09; N, 4.52. UV-vis (CH2Cl2): lmax, nm (log e)
263 (4.72), 422 (5.70), 474 (4.59), 506 (4.75), 555 (4.08),
593 (3.75), 650 (3.77). IR (KBr) nmax, cm-1 3321 (N–H),
2928–2856 (aliphatic-CH), 1701, 1653, 1598, 1505, 1471,
Synthesis of TPP-C12-PIE. The same procedure as
for TPP-C4-PIE with 13 (0.47 g, 0.34 mmol), 3 (0.16 g,
0.28 mmol) and imidazole (5 g), to give the title
compound as a red solid.Yield 0.25 g (40%). Anal. calcd.
for C129H160N6O10: C, 79.26; H, 8.25; N, 4.30, found: C,
79.08, H, 8.26, N, 4.34. UV-vis (CH2Cl2): lmax, nm (log e)
263 (4.72), 422 (5.69), 474 (4.57), 506 (4.73), 556 (4.08),
594 (3.74), 651 (3.76). IR (KBr) nmax, cm-1 3445 (N-H),
2926–2850 (aliphatic-CH), 1699, 1655, 1605, 1505,
1
1462, 1351, 1294, 1246, 1171, 1076, 966, 800, 729. H
NMR (500 MHz; CDCl3; Me4Si): dH, ppm -2.90 (2H,
s, pyrrole-NH), 0.92–0.88 (15H, m, -CH3), 1.46–1.31
(74H, m, -CH2-), 1.65–1.60 (8H, m, -CH2-), 1.83–1.72
(8H, m, -CH2-), 2.00–1.95 (6H, m, -CH2-), 3.65–3.61
(2H, m, -N-CH2-), 4.12 (2H, t, -NH-CH2-), 4.25–4.22
(6H, m, -O-CH2-), 4.33 (4H, t, -O-CH2-), 6.49 (1H, t,
-CO-NH-), 7.27 (6H, d, Ar-H), 8.04–8.00 (4H, m, Ar-H),
8.12–8.07 (6H, m, Ar-H), 8.14 (2H, d, Ar-H), 8.21–8.18
(2H, m, Ar-H), 8.32–8.27 (4H, m, Ar-H), 8.75 (2H, d,
Ar-H), 8.83 (4H, s, Ar-H), 8.86 (2H, d, Ar-H). 13C NMR
(125 MHz; CDCl3) dC, ppm 14.0, 14.1, 22.6, 22.7, 25.7,
26.2, 27.1, 27.2, 28.0, 28.5, 29.28, 29.33, 29.38, 29.47,
29.50, 29.54, 29.57, 29.68, 29.72, 31.5, 31.9, 40.4, 40.5,
65.8, 68.3, 112.69, 112.71, 118.2, 120.0, 120.3, 121.3,
121.6, 122.3, 125.2, 125.3, 128.5, 128.7, 129.0, 130.2,
130.8, 131.7, 131.8, 134.13, 134.18, 134.21, 134.7,
134.8, 135.60, 135.63, 145.5, 159.0, 163.2, 167.7, 168.2.
MS (ESI): m/z 1977 (calcd. for [M + Na]+ 1977).
1
1351, 1290, 1246, 1169, 1078, 965, 799, 738. H NMR
(500 MHz; CDCl3; Me4Si): dH, ppm -2.80 (2H, s,
pyrrole-NH), 0.92–0.88 (15H, m, -CH3), 1.50–1.31 (66H,
m, -CH2-), 1.65–1.60 (8H, m, -CH2-), 1.82–1.75 (8H,
m, -CH2-), 2.01–1.94 (6H, m, -CH2-), 3.65–3.61 (2H, m,
-N-CH2-), 4.26–4.17 (8H, m, -O-CH2- and -NH-CH2-),
4.32 (4H, t, -O-CH2-), 6.55 (1H, t, -CO-NH-), 7.24 (4H, d,
Ar-H), 7.27 (2H, d, Ar-H), 7.99 (2H, d, Ar-H), 8.07 (4H,
d, Ar-H), 8.10 (2H, d, Ar-H), 8.15 (2H, d, Ar-H), 8.23
(4H, d, Ar-H), 8.27 (2H, d, Ar-H), 8.46 (2H, d, Ar-H), 8.76
(2H, d, Ar-H), 8.87–8.85 (6H, m, Ar-H). 13C NMR (125
MHz; CDCl3) dC, ppm 14.0, 14.1, 22.6, 22.7, 25.7, 26.2,
26.4, 26.5, 27.8, 28.5, 29.39, 29.45, 29.49, 29.50, 29.54,
29.68, 29.72, 31.5, 31.9, 40.0, 40.1, 65.8, 68.26, 68.28, 112.7,
118.3, 120.0, 120.3, 121.4, 121.5, 122.4, 125.4, 128.6, 129.0,
130.2, 130.9, 131.7, 131.8, 134.08, 134.14, 134.23, 134.7,
134.9, 135.5, 135.6, 145.4, 158.93, 158.95, 163.3, 167.7,
168.2. MS (ESI): m/z 1921 (calcd. for [M + Na]+ 1921).
Synthesis of TPP-C10-PIE. The same procedure as
for TPP-C4-PIE with 12 (0.57 g, 0.41 mmol), 3 (0.29 g,
0.49 mmol) and imidazole (5 g), to give the title
CONCLUSION
Novel dyads TPP-Cn-PIE (n = 4, 6, 8, 10 and 12) were
synthesized and fully characterized. The UV-vis spectra
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 10–12

MESOGENIC COMPLEMENTARY ABSORBING DYADS BASED ON PORPHYRIN AND PERYLENE UNITS
11
revealed these dyads have broad optical absorption from
9. Yang Y, Zhang ZG, Bin H, Chen S, Gao L, Xue
L, Yang C and Li Y. J. Am. Chem. Soc. 2016; 138:
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the ultraviolet region to the visible region, due to the
complementary absorption of porphyrin and perylene
units. DSC traces and POM textures showed all these
dyads have mesogenic properties, and they formed
face-on alignment on the slide when cooled. When
excited at 423 or 473 nm, the photoluminescent emission
showed a Förster and Dexter type energy transfer from
the perylene unit to the porphyrin unit. At the same time,
the fluorescence quenching degree of porphyrin units
increased as the spacers got shorter. This quenching was
ascribed to intramolecular photoinduced electron transfer
processes. In these processes, the charge-separated states
of molecules, TPP+·-Cn-PIE-·, were formed, which
were further confirmed by the photocurrent generation.
These behaviors made the dyads candidates for single-
component photovoltaic active materials.
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Supplementary information
1
The DSC curves, H- and 13C-NMR, IR and MS
spectra of the dyads are supplied as supplementary
information.
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Acknowledgments
We gratefully acknowledge financial support from
the Natural Science Foundation of China (No. 11364013),
Opening Fund of Guangxi Key Laboratory of Electro-
chemical and Magnetochemical Functional Materials
(EMFM20181101), and the Special Funding for
Distinguished Expert from Guangxi ZhuangAutonomous
Region. We thank Guangxi Key Laboratory of Hidden
Metallic Ore Deposits Exploration for providing support
to the POM measurements.
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