A highly efficient artificial light-harvesting system with two-step sequential energy transfer based on supramolecular self-assembly

Article abstract of DOI:10.1039/d0ta03169k

A highly efficient artificial light-harvesting system (ALHS) in the aqueous phase with a two-step sequential energy transfer process has been successfully constructed based on the host-guest interaction between a water-soluble pillar[5]arene (WP5) and a b

Full text of DOI:10.1039/d0ta03169k

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ARTICLE
Highly efficient artificial light-harvesting system with two-step
sequential energy transfer based on supramolecular self-assembly
a
a
a
c
a
b
Guangping Sun, Weirui Qian, Jianmin Jiao, Tingting Han, Yukun Shi, Xiao-Yu Hu* and Leyong
Wang*
a,d
A highly efficient artificial light-harvesting system (ALHS) in aqueous phase with two-step sequential energy transfer
process has been successfully constructed based on the host–guest interaction between a water-soluble pillar[5]arene
(
WP5) and a bola-type bis(4-phenyl)acrylonitrile derivative (BPT), as well as two different hydrophobic fluorescnet dyes
4,7-bis(thien-2-yl)-2,1,3-benzothiadiazole (DBT) and Nile Red (NiR)). The fabricated ALHS shows an ultrahigh antenna
(
effect (47.8 for the first step and 20.1 for the second step) with a high donor/acceptor ratio of 350:1. It is noted that the
obtained WP5BPT supramolecular nanoparticles possess enhanced aggregation-induced emission (AIE) effect and can
function as an ideal donor to realize the first-step of energy transfer from the WP5BPT assembly to DBT. Moreover,
inspired by the sequential energy transfer in nature, NiR was carefully selected as the second acceptor to fabricate an
efficient two-step sequential light-harvesting system based on WP5BPT-DBT-NiR assembly, which exhibits a high FRET
efficiency of 60.9% and 89.4% for the two-step sequential energy transfer process, respectively. Notably, the emission
color changed from light blue to bright green and then to bright red during this process, thus by tuning the molar ratio of
DBT and NiR, a bright white light emission can be achieved with a high fluorescence quantum yield of 23.5%, which
showed a strong ability of white fluorescence emission and promising applications in visible-light photocatalysis.
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
greatly limiting their application in mimicking natural
2
5
Introduction
In recent years, solar energy, as a kind of inexhaustible clean
energy, has attracted more and more attention from science
and technology.
photosynthetic bacteria in nature,
systems. In natural photosynthesis, more than 200 antenna
chromophores (donor) can absorb light energy and transfer it
26‒30
to one acceptor at the reaction center,
such a high
1
,2
donor/acceptor ratio is still a challenge for conventional ACQ
chromophore in fabricating ALHSs in aqueous solution.
Fortunately, in 2001, Tang and co-workers observed the
phenomenon of aggregation-induced emission (AIE) effect that
Inspired by green plants and some
3
‒6
which can capture,
transfer, and store solar energy effectively to achieve
photosynthesis, a series of artificial light-harvesting systems
31
7
‒9
is exactly opposite to the ACQ effect. In the AIE process, the
17‒20 chromophores are almost nonfluorescent in the molecular
(
ALHSs) have been developed, such as dendrimers, organic
10‒12
13‒16
gels,
porphyrin arrays/assemblies,
biomaterials,
However, most of
32-37
21‒24
state, but become highly emissive in the aggregate state.
Moreover, it is noteworthy that the efficient natural light-
harvesting systems are constructed by the noncovalent
interactions between chlorophyll and protein. Therefore,
compared with traditional ALHSs which are constructed via
covalent bonds,
and organic-inorganic hybrid materials.
these ALHSs have performed in organic solvents due to the
intrinsic hydrophobic effect and their conventional
chromophores (donor), which always suffer from aggregation-
caused quenching (ACQ) effect in aqueous solution, thus
3
8
39‒46
supramolecular light-harvesting systems
constructed by noncovalent interaction can not only avoid
multiple steps of synthesis and purification during the
structure fabrication, but also can be successfully achieved in
aqueous solution, showing more potential in artificial light-
4
7‒55
harvesting.
For example, in 2017, Liu and co-workers reported an
efficient supramolecular ALHS constructed by an AIE molecule,
an oligo(phenylenevinylene) derivative
(
OPV-I), and
a
supramolecular macrocycle, sulfato-β-cyclodextrin
which performed an extremely high antenna effect of 32.5.
Besides, in 2018, our group also fabricated two highly efficient
(
SCD5),
1
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Journal Name
supramolecular ALHSs based on the self-assembly of a water-
soluble pillar[6]arene (WP6), a salicylaldehyde azine derivative
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DOI: 10.1039/D0TA03169K
(G
), and two types of fluorescence dye (Nile red (NiR) or Eosin
Y (ESY)), which showed a high antenna effect of 25.4 and 28.0,
52
respectively. However, most of these systems only involve
one-step direct Förster resonance energy transfer (FRET)
process from the donor to acceptor, while the natural light-
harvesting system with excellent efficiency is characterized by
56,57
multi-channel information communication.
Up to now,
only a few examples of two-step sequential light-harvesting
systems have been fabricated in aqueous environment based
3
8,58,59
on supramolecular self-assembly.
designed a two-step sequential energy transfer system based
on water-soluble pillar[5]arene WP5 and
tetraphenylethylene-functionalized dialkyl ammonium
In 2019, we have
a
(
)
a
38
derivative (TPEDA). But the antenna effect of this two-step
sequential light-harvesting system was only 11.5 and 3.5,
respectively. Therefore, it is still a very challenging task to
design and fabricate highly efficient sequential light-harvesting
systems in aqueous environment.
Fig. 1 Schematic illustration of supramolecular self-assembly of
artificial light-harvesting system with two-step sequential
energy transfer in aqueous solution.
Herein, we report a novel two-step sequential ALHS based
on noncovalent supramolecular self-assembly between WP5
and a bola-type bis(4-phenyl)acrylonitrile derivative (BPT),
which could efficiently realize two-step sequential energy
transfer process in aqueous environment (Fig. 1). As a classical
type of AIE molecule, BPT in the aggregated form can exhibit
high emission and will be an ideal donor for light-harvesting in
3
50:1 and [BPT]/[DBT]/[NiR] = 350:1:1). Notably, a strong
white light emission could be successfully achieved during this
sequential energy transfer process with a high fluorescent
quantum yield of 23.5%. More importantly, based on the AIE
enhanced FRET efficiency, undesired fluorescence self-
quenching could be effectively avoided and two-step as well as
multi-step sequential energy transfer process could be realized
in aqueous solution, thus the present work showed great
potential in mimicking natural photosynthesis based on
supramolecular chemistry.
56,60‒62
aqueous phase.
Meanwhile, considering the brilliant
property of host–guest chemistry and solubility, WP5 will be
an excellent host for BPT to lower its critical aggregation
concentration and significantly strengthen its AIE effect in
water. As shown in Fig. 1, based on the host–guest interaction,
WP5 could directly bind with BPT and further self-assembled
Results and discussion
Investigation of host−guest complexation
into WP5
BPT nanoparticles, which showed blue fluorescence
when excited at 365 nm. Simultaneously, 4,7-bis(thien-2-yl)-
4
8,50
2
,1,3-benzothiadiazole (DBT),
acceptor, was successfully encapsulated into the hydrophobic according to the reported literatures,
core of the formed WP5 BPT-DBT nanoparticles, which was obtained by
two-step reaction using 4-((10-
mainly driven by cooperative hydrophobic, C-H··· and
bromodecyl)oxy)benzaldehyde as the starting material.
stacking interactions. Moreover, since the fluorescence Initially, considering the complicated structure of BPT may
emission band of the WP5 BPT nanoparticles overlaps very hamper the investigation of host–guest interaction with WP5
well with the absorption band of DBT, an efficient one-step GM, a model guest molecule with the same binding site as BPT
energy transfer process took place from the WP5 BPT (Fig. S11, ESI
), was synthesized to investigate the
complex to DBT, which was characterized by the observation complexation between BPT and WP5
as a hydrophobic energy As shown in Fig. S1 and S2 (ESI
†), WP5 was synthesized
6
3‒66
and BPT was

a
40,51,56,67

-

,

†
6
4
.
As shown in Fig. 2, all
3
8,51,52
of strong green fluorescence. Furthermore, NiR
,
another the resonance signals of GM exhibited significantly upfield
hydrophobic fluorescent dye, was carefully selected as the chemical shifts, while WP5 showed slightly downfield chemical
second energy acceptor to realize the two-step sequential shifts, indicating that BPT could bind well with WP5 to form a
energy transfer process, which was confirmed by the supramolecular inclusion complex. Simultaneously, isothermal
observation of obvious fluorescence changing from green to titration calorimetry (ITC) was performed to quantitatively
red. Therefore, such a two-step sequential energy transfer assess the exact binding property between WP5 and GM (Fig.
system (WP5
place from the WP5

BPT-DBT-NiR assembly) could initially take 3). Based on the obtained ITC data, the stoichiometry between
BPT complex to DBT and then to NiR WP5 and GM was confirmed to be 1:1 and the association

4

1
with a high energy transfer efficiency of 60.9% and 89.4%, constant (K ) was calculated to be (4.27 ± 1.22) × 10 M .
a
respectively. Moreover, this ALHS showed an ultrahigh Considering the similar binding site of BPT with WP5, we
antenna effect of 47.8 for the first step and 20.1 for the deduced the association constant between BPT and WP5
4

1
second step with a high donor/acceptor ratio ([BPT]/[DBT] =
should be estimated to be about 10 M , which might be
2
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1
Fig. 2 H NMR (400 MHz, D O, 298 K) spectra: (a) WP5 (8.0
2
mM), (b) WP5 (8.0 mM), GM (4.0 mM), and (c) GM (4.0 mM).
mainly driven by the cooperative hydrophobic, electrostatic,
68‒71
and CH-π interactions.
Fig. 3 Microcalorimetric titrations of WP5 with GM in water at
Construction of supramolecular nanoparticles based on WP5BPT
complex
2
98 K. (a) Raw ITC data of microcalorimetric titrations for 25
sequential injections (1.5 μL per injection) of WP5 solution (6
mM) into the aqueous solution of GM (0.6 mM); (b) “S-type”
heat effects of the complexation between WP5 and GM for
each injection, obtained by subtracting the dilution heat from
the reaction heat, which was fitted by computer simulation
using the “one set of binding sites” model.
Before exploring the energy transfer process, dynamic light
scattering (DLS) experiment was firstly carried out to
investigate the aggregating behavior of WP5BPT complex in
water. Initially, almost no signal could be observed for free
BPT aqueous solution (1 × 104 M, containing 0.2 % DMSO),
indicating no aggregates assembled in free BPT solution.
Meanwhile, no obvious fluorescence could be detected for the
free BPT solution, suggesting that free BPT was hard to self- illustrated in Fig. 1 (Fig. 4d). Subsequently, zeta-potential
assemble into nanoaggregates under the measured condition assays showed that the obtained WP5
BPT nanoparticle
Fig. S12, ESI ). However, when WP5 was added into the free solution possessed a relatively high positive ζ- potential (46.94
BPT solution, a light opalescence and clear Tyndall effect could mV), suggesting the strong repulsive forces around the
be observed immediately (Fig. 4a and S13, ESI ), suggesting surfaces of the WP5
BPT nanoparticles can prevent their
the existence of abundant nanoaggregates. Moreover, the agglomeration in aqueous solution (Fig. S16, ESI
).
WP5 BPT solution showed significantly enhanced blue
fluorescence (Fig. S12, ESI ), confirming that WP5 could induce

(
†
†

†

†
Investigation of the one-step energy transfer process of
WP5BPT-DBT nanoparticles
the self-assembly of BPT at low concentration, resulting in the
obvious AIE effect in return. And the best molar ratio between
BPT and WP5 for aggregation was further determined to be Since WP5 could obviously induce the enhanced AIE effect of
5
ESI
:1 by the optical transmittance experiments (Fig. S14, BPT with fluorescence quantum yield of 3.28% (Fig. S19, ESI
†
),
38,51,52
†
).
Based on this host–guest molar ratio, the critical WP5
BPT nanoparticles could be used as an ideal donor to
aggregation concentration (CAC) of WP5
determined to be 0.1 mM (Fig. S15, ESI ).

BPT solution was construct artificial light-harvesting systems in aqueous phase,
†
which could effectively avoid the conventional fluorescence
Subsequently, the size and morphology of these self-quenching of the aggregated donor chromophores in
supramolecular nanoaggregates were explored by DLS and water. DBT, a hydrophobic fluorescence dye, was firstly
transmission electron microscopy (TEM) measurements. DLS selected as the fluorescent acceptor due to the good overlap
results revealed that the nanoaggregates formed by WP5
complex had a narrow size distribution with an average of WP5
hydrodynamic diameter of 180 nm (Fig. 4a). And TEM images could be successfully encapsulated into the hydrophobic layer
clearly showed the morphology of a dark spherical structure of the WP5
BPT nanoparticles to form tightly stacked
with diameters ranging from 150 to 200 nm, indicating the stacking assembly, which significantly shortened the distance

BPT between the absorption band of DBT with the emission band

BPT nanoparticles (Fig. S17, ESI ). Moreover, DBT
†

-
formation of multilayered spherical core-shell structure as
between the donor and the acceptor, making it possible for
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and Table S1, ESI
WP5BPT-DBT nanoparticles decreased to τ = 0.40 ns and τ =
1 2
†
). However, the fluorescence lifetimes of the
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DOI: 10.1039/D0TA03169K
2
.42 ns when emitting at 450 nm, indicating that the
WP5 BPT-DBT artificial light-harvesting system had been
successfully constructed and the energy could be efficiently
transferred from the WP5 BPT assembly (donor) to the
acceptor DBT (Table S1, ESI ). Subsequently, in order to


†
quantitatively evaluate the ability of this ALHS, it is necessary
to investigate the energy transfer efficiency and antenna
3
8,48,50‒52
effect
of the WP5
. According to the fluorescence quenching ratio

BPT nanoparticles at 450 nm, the energy transfer
efficiency was calculated to be 60.9% with the molar ratio of
donor/acceptor = 350:1 (Fig. S20, ESI ). Furthermore, the
antenna effect was calculated to be 47.8 at such a high
donor/acceptor ratio (Fig. S22, ESI ), indicating the fabricated
2 × 10 M, [BPT] = 1 × 10 M, [DBT] = 2.8 × 10 M, and [NiR
]
WP5 BPT-DBT nanoparticles could function as an excellent
Fig. 4 DLS data: (a) WP5

BPT nanoparticles, (b) WP5
BPT-DBT-NiR nanoparticles.
BPT nanoparticles, (e) WP5 BPT-DBT
nanoparticles, and (f) WP5 BPT-DBT-NiR nanoparticles. [WP5
BPT-
†
DBT nanoparticles, and (c) WP5
TEM images: (d) WP5



†

]

5
4
7

=
=

7
light-harvesting antenna in aqueous environment.
2.8 × 10 M, respectively.
Investigation of the two-step energy transfer process of
WP5BPT-DBT-NiR nanoparticles
achieving the FRET process with high efficiency. As shown in
Fig. 5, with gradual addition of DBT to the WP5
nanoparticles, the fluorescence intensity of the WP5


BPT
BPT Inspired by the photosynthetic light-harvesting systems in
nanoparticles (donor) at 450 nm decreased obviously, while nature, multi-step sequential energy transfer rather than the
the fluorescence emission of DBT (acceptor) at 550 nm simple one-step energy transfer become more meaningful for
3
,38
increased significantly when excited at 365 nm. Moreover, the ALHSs. Therefore, based on the obtained efficient one-step
fluorescence emission changed from light blue to bright green energy transfer of the WP5
BPT-DBT nanoparticles, two-step
Fig. 5b and S26, ESI ). The above phenomena indicated the sequential energy transfer process was further investigated.
efficient energy transfer had taken place from the WP5
assembly (donor) to the encapsulated DBT (acceptor). hydrophobic fluorescence dye, was found quite suitable for
Simultaneously, the fluorescence quantum yield of WP5 BPT- the second-step sequential light-harvesting system due to the
DBT nanoparticles also showed a notable increase (16.85%; Fig. fact that the absorption band of NiR overlaps very well with
S19, ESI ), probably because DBT could accept and emit the the emission band of the WP5
BPT-DBT nanoparticles.
Accordingly, when the second acceptor NiR was gradually
added into the WP5 BPT-DBT nanoparticles, the fluorescence

(
†
38,51,52,72

BPT Based on careful literature survey,
NiR, another

†

52
maximum possible amount of excitation energy,
corresponding to the above process of energy transfer.

In order to further confirm the light harvesting process, intensity of DBT at 550 nm decreased remarkably and the
fluorescence decay experiments were conducted. The decay fluorescence emission of NiR (the second acceptor) at 620 nm
curve of the WP5
exponential decay, which showed the fluorescence lifetimes of Meanwhile, the fluorescence emission changed from bright
τ = 0.60 ns and τ = 2.80 ns when emitting at 450 nm (Fig. 5b
green to bright red (Fig. 6b and S26, ESI ). These results
showed that two-step sequential energy transfer process took
place from the WP5 BPT-DBT nanoparticles to the second
BPT nanoparticles was fitted as a double increased significantly when excited at 365 nm (Fig. 6a).
1
2
†

acceptor NiR. Notably, DBT, as a key bridge, was first used to
realize this sequential energy transfer process in aqueous light-
harvesting system (Fig. S27, ESI
the WP5 BPT-DBT nanoparticles, the fluorescence quantum
yield of the WP5 BPT-DBT-NiR nanoparticles showed a
significant increase again (31.6%) (Fig. S19, ESI ), confirming
†). Furthermore, compared to


†
the occurrence of this two-step energy transfer process. The
energy transfer efficiency was then calculated to be 89.4%
with the molar ratio of donorBPT/acceptorDBT/acceptorNiR
50:1:1 (Fig. S21, ESI ). And the antenna effect was calculated
to be 20.1 (Fig. S23, ESI ), which indicated that the obtained
WP5 BPT-DBT-NiR nanoparticles could function as an
efficient sequential light-harvesting antenna in aqueous
environment. It is worth mentioning that the antenna effect of
this two-step sequential energy transfer was much higher than
that of the recently reported two-step ALHSs in aqueous
=
3
†
Fig. 5 (a) Fluorescence spectra of WP5
water with different concentrations of DBT. (b) Fluorescence
decay profiles of WP5 BPT nanoparticles (black line) and
BPT-DBT nanoparticles (red line). Inset: photographs of
BPT nanoparticles and WP5 BPT-DBT nanoparticles.
BPT nanoparticles in
†


WP5
WP5



WP5] = 2 × 10 M, [BPT] = 1 × 10 M, and [DBT] = 2.8 × 10

5
4
7
[
M, respectively.
4
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Fig. 6 (a) Fluorescence spectra of WP5
in water with different concentrations of NiR. (b) Fluorescence
decay profiles of WP5
BPT-DBT nanoparticles (black line) and Fig.
WP5 BPT-DBT-NiR nanoparticles (red line).
Inset: nanoparticles, WP5
BPT-DBT nanoparticles, white light concentrations of DBT, and WP5
BPT-DBT-NiR nanoparticles. [WP5] = 2 with different concentrations of NiR. Inset: photographs of
BPT-DBT nanoparticles

7
(a) CIE chromaticity coordinates of WP5
BPT-DBT nanoparticles with different
BPT-DBT-NiR nanoparticles
BPT


photographs of WP5



fluorescence, and WP5
10 M, [BPT] = 1 × 10 M, [DBT] = 2.8 × 10 M, and [NiR] = WP5

5

4
7

BPT nanoparticles, WP5
BPT-DBT nanoparticles, white
×
2

7
.8 × 10 M, respectively.
light fluorescence, and WP5
BPT-DBT-NiR nanoparticles. (b)
Fluorescence spectrum of the white light emission coordinate.

5
4

7
[
WP5] = 2 × 10 M, [BPT] = 1 × 10 M, [DBT] = 2.8 × 10 M,
38,58,59
and [NiR] = 2.1 × 10 M, respectively.
7
environments.
Fluorescence lifetime experiments were also performed to
investigate the sequential energy transfer process for the
WP5

BPT-DBT-NiR system. The decay curve of the WP5

BPT- were related to the FRET process, which was induced by the
BPT assembly. Notably,
.36 ns and τ = 2.82 ns when emitting at 550 nm (Fig. 6b and during this two-step sequential energy transfer process, a
DBT nanoparticles showed the fluorescence lifetimes of τ = remarkable AIE effect of the WP5
1

1
2
Table S2, ESI
WP5
BPT-DBT-NiR nanoparticles further decreased to τ = concentration of 0.1 mM (BPT) with the moral ratio of
.11 ns and τ = 2.38 ns (Table S2, ESI
†
). However, the fluorescence lifetimes of the strong white light emission could be obtained at a

1
1
†
) when emitting at 550
nm, indicating that a potential two-step sequential artificial color coordinate of the WP5
light-harvesting system was successfully created and the calculated to be (0.32, 0.33) (Fig. 7a), which is very close to the
[
BPT]/[DBT]/[NiR] = 350:1:0.75 (Fig. 6 and 7). The emission
BPT-DBT-NiR nanoparticles was
2

energy could be efficiently transferred from the WP5
DBT assembly to the second acceptor NiR

BPT- exact white point (0.33, 0.33), showing a potential application
in white-light emission materials. Furthermore, under this
condition, the second-step sequential energy transfer
.
efficiency from the WP5
6.5% and the fluorescence quantum yield of the WP5
DBT-NiR nanoparticles was 23.49% (Fig. S24 and S25, ESI

BPT-DBT nanoparticles to NiR was
BPT-
),
Investigation of the fluorescence emission color of supramolecular
nanoparticles
8

†
Subsequently, the fluorescence emission behavior of the indicating the successful construction of a white-light emission
WP5
BPT-DBT-NiR nanoparticles was investigated. Since the material based on a two-step sequential energy transfer
emission color of the WP5
BPT-DBT-NiR nanoparticles is process. Moreover, such a supramolecular system possessed a
mainly relied on the fluorescence spectrum output, it is hard strong ability of white fluorescence emission and promising


3
8,54,74-77
to judge the perceived color changes of the overall emission applications in visible-light photocatalysis.
5
0
from the spectral evolution. Fortunately, based on the CIE
Commission Internationale de l᾿Eclairage) 1931 chromaticity
diagram, it will be easy to depict the emission color changes by
converting each spectrum to a CIE coordinate and mapping the In summary, we have successfully constructed a two-step
(
Conclusions
48,50,73
coordinates on the corresponding CIE diagram.
in Fig. 7, the WP5 BPT nanoparticles lay in light blue area efficiency based on supramolecular self-assembly, which
without the presence of acceptor. However, with the ratio of showed an ultrahigh antenna effect of 47.8 (first step) and
DBT increased from 6500:1 to 350:1, the emission color of the 20.1 (second step) with
high donor/acceptor ratio
WP5 BPT-DBT system changed from light blue to bright green ([BPT]/[DBT] = 350:1 and [BPT]/[DBT]/[NiR] = 350:1:1). Firstly,
gradually (Fig. 7a and S26, ESI ), indicating an efficient energy a novel one-step artificial light-harvesting system (WP5
BPT-
transfer process occurred from the WP5 BPT assembly to DBT
DBT assembly) was fabricated, which showed enhanced AIE
Furthermore, similar to the one-step energy transfer process, effect and could function as an ideal donor to realize the first-
the sequential energy transfer from the WP5 BPT-DBT step of the energy transfer from WP5
BPT assembly to DBT
As shown sequential aqueous light-harvesting system with excellent

a

†


.


.
nanoparticles (DonorBPT/AcceptorDBT = 350:1) to NiR could be Moreover, inspired by the sequential energy transfer in nature,
observed directly, and during this process the emission color NiR was carefully selected as the second acceptor to fabricate
changed from bright green to bright red (Fig. 7a and S26, ESI
†). an efficient two-step sequential light-harvesting system based
The above results expressed the emission color coordinates
on WP5
BPT-DBT-NiR assembly, which exhibited a high FRET
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J. Name., 2013, 00, 1-3 | 5
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efficiency of 60.9% and 89.4% for the two-step sequential
energy transfer process, respectively. Notably, the
fluorescence emission changed from light blue to bright green
and then to bright red during this process, thus by tuning the
molar ratio of DBT and NiR, a bright white light emission can
be achieved, which showed a strong ability of white
fluorescence emission and promising application in visible-
photocatalysis. This work provides a novel approach for the
construction of a highly efficient two-step sequential light-
harvesting system in aqueous phase based on supramolecular
self-assembly, which possesses an excellent FRET efficiency
and has great potential application in the fields of mimicking
multi-step energy transfer process in nature.
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Journal of Materials Chemistry A
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DOI: 10.1039/D0TA03169K
Graphical Abstract
An efficient artificial light-harvesting system with two-step sequential energy
transfer has been successfully constructed based on supramolecular self-assembly.