Supramolecular light-harvesting systems utilizing tetraphenylethylene chromophores as antennas

Qiaona Zhang , Xiaoman Dang , Fengyao Cui and Tangxin Xiao *
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China. E-mail: xiaotangxin@cczu.edu.cn

First published on 19th August 2024

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Qiaona Zhang

Qiaona Zhang was born in Henan province, China. In 2022, she obtained her BSc degree from Jiangsu Second Normal University. She is currently pursuing her Master's degree under the supervision of Prof. Tangxin Xiao at Changzhou University. Her research interests primarily involve fluorescent materials based on supramolecular self-assembly.

Xiaoman Dang

Xiaoman Dang was born in Shandong Province, China. She received a B. Eng. degree from Shandong First Medical University in 2023. She is currently studying for her Master's degree at Changzhou University, under the guidance of Prof. Tangxin Xiao. Her research focuses on luminescent materials based on macrocyclic host–guest interactions.

Fengyao Cui

Fengyao Cui was born in Henan province, China. She obtained her BSc degree from Henan Agricultural University in 2023. She is currently pursuing her Master's degree under the supervision of Prof. Tangxin Xiao at Changzhou University. Her research interests are centered on fluorescent supramolecular polymeric networks based on quadruple hydrogen bonding.

Tangxin Xiao

Tangxin Xiao received his PhD in supramolecular chemistry from Nanjing University under the supervision of Prof. Leyong Wang in 2014. Following postdoctoral research on fine chemicals at the Zhejiang University-NHU Company United R&D Center, he joined Changzhou University in 2017. He was promoted to Associate Professor in 2020 and to Professor in 2023. From 2021 to 2022, he was funded by the China Scholarship Council (CSC) as a visiting scholar in Prof. Oren Scherman's group at the University of Cambridge. His current research interests focus on supramolecular chemistry and luminescent materials. He has co-authored more than 80 publications, with over 4000 citations and an H-index of 31.

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1. Introduction

The current global energy crisis presents a significant challenge, highlighting the need for the pursuit of clean and cost-effective energy solutions on a global scale. Taking cues from nature, scientists are turning to photosynthesis as a source of inspiration to address this pressing issue.^1,2 Photosynthesis, a ubiquitous process observed in green plants and photosynthetic bacteria, holds promise for generating clean energy.^3,4 Recognized for its pivotal role in sustaining life, photosynthesis operates as an efficient mechanism wherein photons are harvested by a vast array of densely packed chlorophyll molecules within a pigment–protein complex.^5,6 This process yields both chemical energy and oxygen, essential for the survival of organisms. Notably, the inherent efficiency of photosynthesis enables organisms to thrive even in environments with limited light availability.^7,8 Consequently, photosynthesis serves as a proficient means of capturing, transmitting, and storing solar energy. Motivated by these natural mechanisms, scientists are actively engaged in the development of artificial light-harvesting systems (LHSs) designed to emulate the efficiency of photosynthesis.^9–16

Antenna chromophores play a crucial role in absorbing and transmitting light energy within LHSs.^17–21 To mitigate the loss of harvesting light energy within these chromophores, Förster resonance energy transfer (FRET)^22–24 stands out as a viable mechanism for efficient energy transfer. Consequently, the antenna chromophores also function as energy donors, channeling absorbed light energy to energy acceptors to facilitate the light-harvesting and energy-transfer process. In the endeavor to construct efficient artificial LHSs based on FRET mechanisms, three critical factors need to be considered: (1) maintaining a high donor-to-acceptor (D/A) molecular ratio; (2) ensuring wavelength matching and appropriate distance (ranging from 0.1 to 10 nm) between the donor and acceptor for effective energy transfer, (3) mitigating emission quenching in donors, even under conditions where multiple donor molecules are densely packed in close proximity.²⁵ To meet these stringent criteria and advance the development of LHSs, antenna chromophores exhibiting aggregation-induced emission (AIE)^26,27 behavior emerge as a highly promising and pragmatic option.²⁸

Among the AIE chromophores used for this purpose, tetraphenylethylene (TPE) has emerged as an exceptionally compelling candidate as an antenna chromophore, owing to its unique properties.^29–31 These include facile synthesis and modification, high absorption efficiency, and robust fluorescence emission in the aggregated state. Supramolecular self-assembly is a process wherein building blocks spontaneously organize into ordered aggregates without human intervention. The interactions driving this process are typically noncovalent in nature, and they often include host–guest interactions, hydrogen bonding, metal–ligand coordination, hydrophobic interactions, and electrostatic interactions, among others. In recent years, the amalgamation of supramolecular self-assembly and AIE has ingeniously converted disordered aggregation luminescence into ordered assembly luminescence, significantly mitigating the challenges associated with synthesizing luminescent materials while imparting them with stimuli-responsive properties.^32–34 In this context, TPE has emerged as a promising building block for assembling supramolecular light-harvesting architectures. Leveraging the intrinsic characteristics of TPE, notably its potent light-harvesting capability and efficient energy transfer, researchers have fervently endeavored to devise novel supramolecular LHSs endowed with enhanced performance and multifunctionality. Through meticulous molecular design and supramolecular engineering, these systems can manifest augmented antenna effects (the amplification of the emission intensity of the acceptor after it absorbs excitation energy from the donor) and customizable emission properties, thereby fostering applications across diverse light-related domains.

In this Feature Article, we focus on the burgeoning field of supramolecular LHSs utilizing TPE chromophores as antennas. Notably, this article will not discuss supramolecular LHSs based on other donor fluorophores,^35–38 including cyanostilbene,^39–41 salicylaldehyde azine,⁴² carbazole,⁴³ anthracene,^44–48 pyrene,^49–52etc. Herein, we embark on an exploration of the fundamental principles underpinning the design and synthesis of these TPE-based assemblies, elucidate the intricate mechanisms governing the energy transfer process, and discuss their prospective applications in an array of domains including sensing, photocatalysis, information encryption, bio-imaging, and fingerprint recognition, among others. The article is structured around the following focal points: (1) TPE-based LHSs assembled through host–guest interactions, (2) TPE-based LHSs assembled via quadruple hydrogen bonds, (3) TPE-based LHSs assembled through hydrophobic interactions, (4) TPE-based LHSs assembled via metal coordination, and (5) TPE-based LHSs assembled by multiple non-covalent interactions. Furthermore, we provide a profound outlook on the development direction and challenges confronting the next generation of TPE-based supramolecular LHSs.

2. LHSs based on host–guest interaction

Host–guest interaction refers to the forces that allow two or more chemical substances form assemblies through molecular recognition.^53,54 This interaction is one of the most commonly used driving forces for constructing molecular assembly systems. The relationship between host and guest in such interactions is analogous to that of a lock and key. Under conditions of structural complementarity and energy matching, supramolecular systems with specific functions can be formed through the selective binding of host–guest interactions. In recent years, macrocyclic host molecules such as cucurbit[n]urils and pillar[n]arenes have been utilized to induce guest molecules containing TPE groups to form well-defined nanoaggregates in aqueous solution, thereby enhancing the fluorescence of TPE. This process plays a significant regulatory role in the construction of LHSs.

2.1 Pillar[n]arene

Pillar[n]arenes are macrocyclic molecules consisting of dialkoxybenzene groups connected by methylene groups at para-positions.^55–57 The symmetrical pillar architecture of pillar[n]arenes endows them with excellent guest-binding capabilities. As the latest generation of widely-used macrocyclic hosts, the extensive application of pillar[n]arene derivatives has significantly advanced the field of macrocyclic and supramolecular chemistry. Wang and co-workers pioneered research on LHS based on pillar[n]arenes. As early as 2015, they developed supramolecular polymers based on boron-dipyrromethene (BODIPY)-bridged pillar[5]arene dimers and BODIPY-derived guests to mimic the LHS of natural photosynthesis in organic solutions.⁵⁸ In 2018, they further advanced highly efficient artificial LHSs in aqueous environments using a water-soluble pillar[6]arene as the host and a salicylaldehyde azine derivative as the guest.⁷ Since then, numerous supramolecular LHSs based on pillar[n]arenes have been developed. In this section, we focus on pillar[n]arene-based LHSs utilizing TPE as donor chromophores.

The self-assembly of low molecular-weight guest and host is a facile approach achieving nanoaggregates. In 2022, our research group designed and constructed a supramolecular LHS utilizing water-soluble pillar[5]arene (WP5) as the host, methylpyridinium-modified bola-type TPE derivative (G1) as the guest, and fluorescent dye SR101 as the energy acceptor (Fig. 1(a)).⁵⁹ Due to the AIE property of G1, it can prevent fluorescence quenching in the aggregated state. Therefore, G1 plays a dual role, binding to the host and acting as an energy donor. In the presence of WP5, it was observed that the methylpyridyl group of G1 can form a host–guest complex with WP5 and subsequently self-assemble into micellar nanoparticles (NPs). WP5 significantly reduces the critical aggregation concentration (CAC) of G1, leading to a marked enhancement of the AIE of G1. Subsequently, the commercially available dye SR101 can be loaded into the NPs, enabling the excitation light to be collected by G1 in the NPs and then transferred to SR101. The system exhibits tunable fluorescence emission by adjusting the D/A molar ratio and can achieve white-light emission when D/A = 250/1. In a follow-up work, we further used methylpyridinium-modified tadpole-type TPE derivative (G2) as the guest. After complexing with WP5, the resulting host–guest complex can further self-assemble into fluorescent NPs in water (Fig. 1(b)).⁶⁰ By encapsulating the commercially available dye rhodamine 6G (Rh6G) into these NPs, efficient artificial LHSs with high D/A ratios (>400/1) could be successfully constructed. Finally, this system was utilized as a fluorescent ink for information encryption.

Considering the excellent properties of supramolecular chemistry and the stability of covalent polymers, both of which are highly desirable in the construction of functional materials, the introduction of polymer hosts with multiple synthetic macrocycles on the side chains can enhance fluorescence performance, stability, solubility, and processability by leveraging the advantages of covalent polymers. In 2019, Tang, Yang and co-workers synthesized a new type of linear copolymer host (Fig. 1(c)).⁶¹ Pillar[5]arenes are regularly suspended on the long chains of linear copolymers as the host sites (poly-P[5]A), and a multifunctional TPE derivative (TPE-(TA-CN)₄) is used as guest molecule. A supramolecular polymer network (SPN) was formed through host–guest recognition, thereby constructing an efficient and adjustable artificial LHS. The formation of this SPN increases the density of the pillar[5]arene macrocycles and achieves closer binding to the TPE derivatives embedded in the polymer network. The resulting supramolecular assemblies exhibit strong fluorescence emission with a very high fluorescence quantum yield of 98.22%. Subsequently, LHSs were fabricated by incorporating another yellow-emission fluorescent molecule, DSA-(TA-CN)₂, into the SPN, resulting in an array of spherical supramolecular NPs with tunable colors, from cold to warm tones. This work not only proposes a new concept of polymer host, but also constructs color-tunable supramolecular light-harvesting NPs by introducing acceptors with different fluorescence emission. This opens up a new path for tunable supramolecular organic luminescent materials and shows potential applications in sensing, bio-probing, and optoelectronic devices.

In 2020, H. Tang, Cao, B. Z. Tang, and co-workers reported an artificial LHS with unprecedented antenna effects based on a conjugated polymeric supramolecular network (CPSN).⁶² As shown in Fig. 1(d), they first prepared a crosslinked network through the self-assembly of a pillar[5]arene-based conjugated polymeric host (CPH) and conjugated ditopic guests. The CPH was synthesized by integrating pillar[5]arenes and TPE groups into the polymer backbones via a click reaction. The TPE groups functioned both as antennae and energy donors. Additionally, the ditopic molecules (GR, GB, GY) acted as both guests and energy acceptors. Through host–guest interaction, a tightly bound CPSN with the capability of energy transfer was formed. By altering the D/A ratio, the CPSN achieved tunable multicolor and efficient fluorescence emission. This color range cover 96% of the CIE chromaticity diagram, including pure white-light emission with coordinate points of (0.33, 0.33). Consequently, the LHS exhibited an ultra-high antenna effect, with a measured value of 35.9 in solution and up to 90.4 in solid films. This work provides an alternative strategy for creating strongly luminescent materials. In a subsequent study, they designed and synthesized an assembly-induced emission orthogonal supramolecular network (AOSN) for constructing artificial LHSs.⁶⁵ The AOSN was constructed through host–guest interactions between a tetratopic conjugated host bearing four pillar[5]arene units and a ditopic guest bearing a TPE group. The conjugated structures of both the host and guest enhanced the energy transfer capability through molecular wire amplification, offering a new strategy for fabricating highly efficient LHSs.

The aforementioned cases involve LHSs with only one-step energy transfer. However, natural LHSs typically feature multi-step energy transfer processes when funneling excitation energy to the reaction center. Inspired by nature, multi-step LHSs containing multiple acceptor chromophores have garnered significant interest in recent years. For example, a two-step FRET system typically includes one energy donor and two energy acceptors, namely the relay acceptor and the final acceptor. The donor chromophores function as light-collecting antennas, capturing the excitation energy and delivering it to the final acceptor via the relay receptor. In 2021, Zhang, Liu and co-workers utilized a pyridine-modified TPE derivative (Py-TPE) as the guest and WP5 as the host to form NPs with blue fluorescence emission through host–guest interaction (Fig. 1(e)).⁶³ Using this NPs as the energy donor, SR101 and sulfonated aluminum phthalocyanine (AlPcS₄) were co-assembled into the NPs as the first and second energy acceptors to achieve two-step sequential energy transfer. In this system, the fluorescence color varied from blue to near infrared, resulting in a Stokes shift of up to 340 nm.

Building on our previous study of the one-step LHS assembled by the bola-type TPE derivative G1 and WP5,⁵⁹ we recently utilized WP5 and G1 to construct an efficient two-step energy transfer LHS in water (Fig. 1(f)).⁶⁴ By introducing ESY as the relay acceptor into the NPs, the excitation energy of WP5⊃G1 can be efficiently transferred to the final receptor, SR101. The total energy transfer efficiency of the host–guest system can reach 94%. Furthermore, the radiative rate constant (k_r) of WP5⊃G1 is almost 8-fold higher, and the emission brightness (ε(λ_abs) × f_F) is nearly doubled. This work not only demonstrates a strategy for constructing efficient sequential LHSs, but also paves the way for preparing bright organic luminescent nanomaterials.

Constructing a light-harvesting system is not only intended to mimic natural process, but also to achieve various functional applications, such as photocatalysis, imaging, information encryption and optoelectronic device. In 2020, Hu, Wang, and co-workers constructed an artificial LHS with a sequential energy transfer process based on supramolecular host–guest strategy (Fig. 2(a)).⁶⁶ The water-dispersed NPs were assembled from WP5 and a bola-type TPE-functionalized dialkylammonium derivative (TPEDA). By utilizing WP5⊃TPEDA as the donor and two hydrophobic dyes, eosin Y (ESY) and Nile Red (NiR), as the first and second acceptors, respectively, an efficient supramolecular LHS with two-step FRET was created. To fully exploit the harvested energy, the WP5⊃TPEDA-ESY-NiR system was successfully used as a nanoreactor to achieve photocatalytic dehalogenation of α-bromoacetophenone in an aqueous medium, achieving a yield of up to 96%.

Inspired by the aforementioned bola-type guest based on TPE, our research group synthesized a new tadpole-type molecule, G3, and employed it along with WP5 to construct an efficient two-step energy transfer LHS (Fig. 2(b)).⁶⁷ This work also utilize ESY as the relay acceptor and NiR as the final acceptor. Due to the dynamic nature of the system, it exhibited tunable photoluminescence. A bright white-light emission with a fluorescence quantum yield of 31.52% was achieved when the molar ratio of [WP5⊃G3]/[ESY]/[NiR] was 10000:10:4. A blue LED bulb was coated with the LHS, and upon applying a 3 V bias, it generated bright white-light emission. This work not only provides an alternative method for the construction of sequential LHSs, but also offers prospects for potential applications in white-light emitting devices.

Fingerprints are unique to individuals and are one of the most important means of identification. Today, the extraction and identification of fingerprints have become indispensable methods in case detection and forensic science. However, the fingerprints left at a crime scene are often latent fingerprints (LFP), making them difficult to observe. In 2023, our research group developed a red-emissive material using a light-harvesting strategy for high-resolution imaging of LFP (Fig. 2(c)).⁶⁸ In that work, we designed and synthesized a bridged TPE derivative (G4) flanked by two dialkylammonium groups as the guest, which complexed with WP5 in water to form yellow luminescent NPs. Subsequently, a LHS with strong red fluorescence was constructed by adding 1% fluorescent dye, NiR, as an energy acceptor. The LHS was then formulated into fluorescent fingerprint powder and applied to three-level fingerprint imaging with high resolution. By analyzing and identifying the subtle structures of the fingerprint, the characteristic features, such as short ridges, terminals, wrinkles, bifurcations, crossovers, core points, spurs, and even sweat pores, could be clearly observed at high magnification. This capability has significant application value for personal identity recognition. This work adds new value and applications to the supramolecular light-harvesting strategy and provides a novel method for high-resolution imaging of LFP.

Photosensitizers (PS) with controllable switching can be activated to produce reactive oxygen species (ROS) under specific wavelength of light irradiation. These ROS is widely used in photodynamic therapy for anticancer and antibacterial applications. Due to their inherent dynamic and reversible characteristics, host–guest interactions provide an efficient and convenient method to control the “on–off” switchability of ROS generation. In 2023, Zuo, Hu, and co-workers utilized a TPE-derived pillar[5]arene host (TPEWP5) with AIE activity, a spiropyran derivative (SP-G) guest and Nile blue (NiB) to construct a supramolecular PS based on a two-step FRET process in aqueous phase (Fig. 2(d)).⁶⁹ The TPEWP5 and SP-G assembled into NPs in water. Interestingly, the reversible isomerization of SP-G endowed the PS with an “on–off” function. Under UV irradiation, the non-fluorescent guest SP-G converted into fluorescent MC-G. The in situ formed MC-G acted as a primary energy acceptor and an effective PS to produce ROS. Additionally, the introduction of NiB served as a secondary energy acceptor, further synergistically promoting the generation of ROS. The prepared NPs were successfully used for in vitro anti-cancer and anti-bacterial treatment through specific light irradiation. This work provides a novel approach to fabricating smart PS materials based on a supramolecular strategy.

2.2 Cucurbit[n]urils

Cucurbit[n]urils (CB[n]s) are supramolecular macrocycles with a pumpkin-like shape, exhibiting excellent host–guest complexation in aqueous media.^70,71 Each port of CB[n] has a circle of polar carbonyl groups, while the middle features a hydrophobic cavity. CB[n] can bind organic cation guests through host–guest complexation, inhibiting their molecular motion, altering molecular conformation, and changing stacking modes. This regulation of the photophysical properties of guest molecules by CB[n] has led to significant advancements in the construction of artificial LHSs.^72,73 In this section, we will discuss TPE-based LHSs assembled using CB[n]s.^74,75

CB[8]-based host–guest interactions are often utilized as the driving force for the construction of supramolecular organic frameworks (SOF) due to their high binding strength.^76,77 To explore the application of SOFs in the construction of artificial LHS, in 2023, Xing and co-workers developed a SOF-based LHS using CB[8] and TPE-derived guests for enhancing the aerobic cross-dehydrogenative coupling (CDC) reaction in an aqueous environment (Fig. 3(a)).⁷⁸ The authors first synthesized two guest molecules: a TPE derivative MV-TPE with four methylated viologens groups and a TPE derivative NA-TPE with four methoxynaphthyl groups. In the presence of CB[8], MV-TPE and NA-TPE self-assembled into SOF through host–guest interaction. Subsequently, fluorescent dyes 4,7-bis(thien-2-yl)-2,1,3-benzothiadiazole (DBT) and SR101 were added into the SOF as the first and second energy acceptors, respectively, to achieve an efficient LHS with two-step sequential energy transfer in water. Finally, this SOF-based LHS was successfully used as a photocatalyst to promote the aerobic CDC reaction in water, achieving a yield of up to 87%. This work demonstrates a novel strategy for fabricating supramolecular LHSs for photocatalysis.

As described above, CB[8] can form ternary complexes by encapsulating two guest moieties in its large cavity. Nor-seco-cucurbit[10]uril (ns-CB[10]) is a relatively new member of the CB[n] family, featuring two cavities, each consisting of five glycolurils connected by two CH₂ bridges. Thus, ns-CB[10] can also bind two guests simultaneously to form a ternary host–guest complex. In 2024, Xiao and co-workers constructed a supramolecular assembly based on a TPE derivative (IMZ-TPE) with four benzyl imidazolium units and ns-CB[10] (Fig. 3(b)).⁷⁹ The four benzyl imidazolium units of IMZ-TPE can be encapsulated in the cavity of ns-CB[10], forming stable supramolecular assemblies. By co-assembling the acceptor dye rhodamine B (RhB), an obvious energy transfer process from the IMZ-TPE@ns-CB[10] assembly to RhB was observed. Furthermore, the addition of the second acceptor NiR enabled a second step of energy transfer. Additionally, introducing ESY into the IMZ-TPE@ns-CB[10] system also achieved an effective LHS. Both systems were used as photocatalysts to catalyze the dehalogenation of α-bromoacetophenone. When promoted with 0.5 mol % catalyst, the reaction yield reached 78% and 68%, respectively. This work provides a new strategy for fabricating LHSs based on ns-CB[10] and demonstrates their application in photocatalytic reactions.

2.3 Other macrocyclic hosts

As mentioned previously, LHSs based on pillar[n]arenes and CB[n] have been extensively studied for efficient photocatalysis, whereas resorcinarene-based cavitands with deep cavities have been less frequently reported for constructing LHSs. In this context, Wang, Hu, and co-workers reported a novel LHS with two-step energy transfer, constructed from the self-assembly of a TPE-based diamantadine derivative (TPEG) and a deep-cavity cavitand (H) (Fig. 4(a)).⁸⁰ The host–guest complex, H⊃TPEG, was formed in aqueous solution through hydrophobic interaction, which further assembled into NPs. Upon co-assembly with the acceptor dyes ESY and NiR, an efficient sequential LHS was successfully constructed in water. The system not only demonstrated white-light emission by adjusting the D/A molar ratio but also showed significant photocatalytic ability for the CDC reaction. This study expands the range of supramolecular hosts available for the construction of LHSs and demonstrates great potential for applications in photocatalysis.

In another work, Lin, Jiang, and co-workers synthesized a novel water-soluble phosphate-based derivative, WPCTX, derived from cyclotrioxyhydroquinone (Fig. 4(b)).⁸¹ It is well established that phosphoric acid and its salts exhibit enhanced biocompatibility in biological systems. WPCTX represents a new class of water-soluble macrocycles, which self-assembled with a TPE-based guest molecule, TPEN, to form WPCTX-TPEN NPs in aqueous solution. Furthermore, hydrophobic dyes, ESY or NiR, were able to co-assemble into the NPs, resulting in the formation of two distinct types of LHSs, respectively. Consequently, significant antenna effects were observed, with values of 9.1 for ESY-loaded NPs and 11.0 for NiR-loaded NPs, which are notable for mimicking natural LHSs. Importantly, this biocompatible macrocycle demonstrates considerable potential for drug delivery and other biomedical applications.

3. LHSs based on quadruple hydrogen bonding

Quadruple hydrogen bonding is a critical supramolecular interaction with significant potential for creating supramolecular polymers and other specific architectures.^82–84 Supramolecular polymers based on quadruple hydrogen bonds exhibit unique dynamic reversibility and environmental responsiveness, making them excellent candidates for designing various functional materials. As early as in 2014, Yang and co-workers synthesized four ditopic ureidopyrimidinone (UPy) compounds: D1, D2, D3, and D4 (Fig. 5(a)).⁸⁵ These monomers formed linear supramolecular polymers in chloroform, driven by quadruple hydrogen bonding, and subsequently transformed into water-dispersed nanospheres through a mini-emulsion method facilitated by cetyl trimethyl ammonium bromide (CTAB) surfactant. The authors suggest that the hydrogen bonds of supramolecular polymers are protected by the hydrophobic microenvironment provided by the emulsified organic droplets during their preparation in aqueous solution. To mimic the natural LHSs, they selected a mono-functionalized UPy-derived anthracene derivative with green fluorescence as the energy acceptor, owing to its good absorption overlap with the emission of the energy donor D4. In this system, with D/A ratios of 58:1, 88:1, and 176:1, the antenna effects were observed to be 13, 20, and 29, respectively. Compared with covalent counterparts, the composition and functions of supramolecular polymeric NPs formed from small monomers are easily tunable.

Most organic AIEgens exhibit broad emission spectra with full width at half-maxima (FWHM) exceeding 100 nm, which is a disadvantage of their practical applications. In 2019, Niu, Yang and co-workers utilized light-harvesting strategies to prepare supramolecular polymer AIE materials that exhibit brighter fluorescence and narrower emission bands, thus achieving higher color purity compared to traditional AIE dyes.⁸⁹ Specifically, these AIE nanomaterials, including NPs, microfibers, and thin films, were fabricated from supramolecular polymers based on TPE-derived quadruple hydrogen bonding monomers as antenna chromophores and BODIPY derivatives as energy acceptors. The excitation energy of TPE molecules was efficiently transferred to BODIPY, resulting in a six-fold increase in fluorescence intensity and a significant narrowing of the emission band, with the FWHM reducing from 148 nm to 32 nm. The resulting NPs are approximately five times brighter than commercial quantum dots. These highly fluorescent NPs were successfully applied to in vitro and in vivo fluorescence and chemiluminescence imaging, demonstrating superior imaging performance compared to conventional AIE NPs.

In natural photosynthesis, the excitation energy is transferred from the antenna chromophore to the reaction center, initiating a series of electron transfers and ultimately converting light energy into chemical energy. However, most supramolecular LHSs primarily utilize the harvested energy via FRET to enhance the emission of the acceptor. In a follow-up work, Niu, Yang and co-workers reported a supramolecular LHS that combines electron transfer and excitation energy transfer to achieve photocatalysis of chemical reactions (Fig. 5(b)).⁸⁶ In the system, the UPy-functionalized TPE derivative, D0, was selected as the antenna chromophore, while an iodine-substituted BODIPY derivative, A0, was used as the energy acceptor. Driven by quadruple hydrogen bonding, D0 and A0 self-assembled into supramolecular NPs. Upon light irradiation, D0 transitioned to the excited state, followed by rapid FRET to A0 with high energy transfer efficiency (Φ_ET = 95.3%). Concurrently, the excited A0 captures an electron from the nearby D0, inducing charge-separation and generating radical ions, D0⁺˙ and A0⁻˙, which were subsequently used to produce H₂O₂. Furthermore, the LHS was successfully employed in photodynamic therapy (PDT) by oxidizing 1,4-dihydronicotinamide adenine dinucleotide (NADH), an electron-donating molecule in living organisms, to generate cytotoxic ROS that kill tumor cells. This study establishes a paradigm that provides significant inspiration for constructing artificial LHSs with efficient excitation energy and electron transfer.

In another work, a supramolecular LHS based on a TPE-derived quadruple hydrogen bonding network was reported by Xing and co-worker.⁹⁰ In recent years, our research group has also constructed various TPE-derived LHSs based on UPy self-assembly.^87,88,91,92 For example, we designed and synthesized a phenyl-fixed TPE monomer with ditopic UPy moieties (D5) as building block and energy donor (Fig. 5(c)).⁸⁷ Using the mini-emulsion strategy, D5 self-assembled into supramolecular polymeric NPs driven by quadruple hydrogen bonding and hydrophobic interactions. Upon encapsulating a hydrophobic dye, NDI, as the energy acceptor into the NPs, an efficient LHS was constructed.

In a follow-up investigation, we constructed a stepwise energy-transfer LHS using a TPE bridged UPy devrivetive (D6) as the energy donor, and two hydrophobic dyes, DBT and NDI, as the first and second energy acceptors, respectively (Fig. 5(d)).⁸⁸ Supramolecular polymeric NPs were formed through a mini-emulsion strategy in aqueous media with the assistance of CTAB, resulting in a strong cyan emission solution. Herein, the quadruple hydrogen bonding plays two roles: bringing the monomers together and enhancing the AIE property. The resulting LHS exhibits tunable fluorescence emission with a broad spectrum from blue to near-infrared emission, including pure white light emission. Notably, this two-step LHS demonstrates a high antenna effect of up to 63 when (D6/DBT/NDI = 1250/25/1). This cascade energy transfer system based on supramolecular polymeric NPs has great potential for mimicking photosynthesis and advancing tunable organic fluorescent materials.

4. LHSs based on hydrophobic interaction

TPE derivatives are generally hydrophobic molecules. To activate their AIE effect, these TPE-based organic molecules can be converted into dispersed nanoaggregates in an aqueous environment. There are two strategies for preparing TPE-based nanoaggregates driven by hydrophobic interactions: (1) constructing disordered nanoaggregates via reprecipitation in mixed organic/aqueous solvents; and (2) constructing ordered nanoaggregates by attaching hydrophilic groups to TPE, as the resulting amphiphilic molecules can self-assemble into well-defined nano-assemblies. The formation of these nanoaggregates not only activates the AIE effect of TPE but also enables their use as nanocarriers to incorporate acceptor dyes, ensuring efficient FRET and thereby constructing effective LHS.

In 2019, Cao and co-workers reported the one-pot synthesis of TPE-based tetracationic dicyclophane (TPE-3) and its application in the construction of an LHS in H₂O/MeCN mixed solvents.⁹³ As depicted in Fig. 6(a), TPE-3 was synthesized via an S_N2 reaction of tetrapyridyl TPE (TPE-1) with bis(bromomethyl) TPE (TPE-2) at a molar ratio of 1:2. The SEM images of TPE-3 in a mixed MeCN/H₂O (the water fraction f_w = 90%) solution revealed a nanosphere structure with diameters ranging from 25 to 77 nm. Due to the supramolecular framework with cavities/interspaces in the NPs, the organic dye NiR can be dispersed within NPs as an acceptor to achieve efficient energy transfer. This was confirmed by fluorescence titration of a TPE-3 solution with NiR, which demonstrated the emission intensity of the donor at 580 nm gradually decreased, while the fluorescence peak of the acceptor at 650 nm gradually increased. In a MeCN/H₂O mixed solvent (f_w = 90%), when D/A = 1:4.5, the energy transfer efficiency (Φ_ET) and the antenna effect of the supramolecular LHS were 77.5% and 14.3 respectively. The supramolecular LHS may have the potential for bioimaging, cancer diagnosis and photodynamic therapy as a fluorescent material.

In recent years, our group has also reported several TPE-based LHSs that are driven by hydrophobic interactions in aqueous environments, demonstrating diverse applications.^94,97,98 For example, in 2022, we designed and synthesized a spirocyclic spacer bridged TPE dimer (TPE-4), where the spacer and TPE are connected by a Schiff-base unit (Fig. 6(b)).⁹⁴ The TPE unit imparts AIE properties to TPE-4, while the Schiff-base unit confers excited-state intramolecular proton-transfer (ESIPT) behavior. Consequently, bright fluorescent NPs with large Stokes shift were obtained from TPE-4 by reprecipitation based on the ESIPT–AIE dual mechanism. Additionally, a tunable LHS was prepared in a THF/H₂O mixed solvent (f_w = 90%) using TPE-4 as a donor and the hydrophobic dye NDI as an acceptor, based on the ESIPT–AIE–FRET triple fluorescence mechanism. At a relatively high D/A ratio (D/A > 200/1), the antenna effect of this LHS was measured to be 20. Further investigations showed that both TPE-4 NPs and the TPE-4@NDI LHS exhibited outstanding Cu²⁺ ion sensing capabilities, providing a more accurate and promising method for detecting Cu²⁺ ions. This work paves the way for the development of tunable fluorescent materials and shows great potential in the field of ion sensing via light-harvesting strategies.

Synthesizing TPE-based amphiphilic molecules is an alternative method to prepare NPs in water.^99–101 Notably, such NPs form ordered nano-assemblies with strong fluorescence emission. To construct a fluorescence probe for sensing temperature in living cells, Zhang, Tang, and co-workers developed a sequential energy-transfer LHS system based on a TPE cage (Fig. 6(c)).⁹⁵ Nucleophilic aromatic substitution of tetrahydroxy-TPE with 2,4,6-trichloro-1,3,5-triazine afforded the cage TC1, which was further converted into an amphiphilic cage, CNP, by decorating it with poly(N-isopropylacrylamide) (PNIPAM). CNP self-assembled into blue-fluorescent NPs in aqueous media. By incorporating two acceptor dyes, 4-dimethylamino-2′-butoxychalcone (DMBC) and NiR, a sequential FRET system was constructed. The fluorescence color of these hybrid NPs can be adjusted across the full visible spectrum by tuning the D/A ratio. Notably, the temperature-responsive PNIPAM groups endow the NPs with lower critical solution temperature (LCST) behavior, producing a thermo-responsive luminescent material. Furthermore, the authors successfully applied the NPs for temperature sensing in living cells via fluorescence color changes. This approach to bio-sensing not only avoids tedious synthesis but also achieve high resolution.

In the past three years, our research group has focused on designing and synthesizing low-molecular-weight amphiphilic molecules to achieve self-assembled functional luminescent materials in aqueous media.^102–105 In 2024, we further synthesized an amphiphilic monomer, TPEO, with temperature-sensitive properties to construct a thermo-responsive LHS with two-step energy transfer in aqueous media (Fig. 6(d)).⁹⁶TPEO is a tadpole-type amphiphile containing a hydrophobic TPE segment and hydrophilic oligo (ethylene glycol) (OEG) chains, which self-assembled into fluorescent micelles in water. The OEG chains endow it with LCST behavior, making the solution transparent at room temperature but turning turbid when heated to 47.5 °C. ESY and SR101 were co-assembled into the NPs as the first and second energy acceptors to form a sequential FRET system. This work interestingly integrates sequential FRET and LCST into a single system, thereby demonstrating temperature-responsive colorimetric fluorescence in both aqueous solutions and hydrogels.

5. LHSs based on metal–ligand coordination

Metal coordination interactions possess excellent directionality and strength, making them a valuable strategy for constructing a range of supramolecular assemblies, including metallacycles, metallacages, and coordination polymers.^106,107 The integration of metal coordination and AIE fluorophores has led to the development of novel supramolecular fluorescent materials.²⁹ As early as 2005, Würthner and co-workers pioneered to construct an artificial LHS based on metal-coordinated square assembly.¹⁰⁸ In recent years, various TPE-based LHSs have been constructed using metal–ligand coordination. This section will focus on these supramolecular LHSs.

In 2021, Zhang, Yi and co-workers synthesized a quadrilateral platinum(II) metallacycle containing four TPE moieties (M1) (Fig. 7(a)).¹⁰⁹M1 can further self-assemble into nanospheres in a H₂O/CH₃OH solvent mixture (f_w = 95%) solvent. Benefiting from the AIE characteristics, M1 serves as an excellent donor chromophore in LHSs. Therefore, they constructed the first sequential two-step energy transfer LHS based on a metallacycle, utilizing ESY and SR101 as the cascaded energy acceptors. This two-step LHS functioned as a photocatalyst for the alkylation of C–H bonds in water, exhibiting considerable yields. In a subsequent work, they advanced further by building a three-step cascaded LHS with tunable efficiency using a new TPE-based metallacycle and three energy acceptor dyes.¹¹⁰ Recently, Jiang and co-workers developed a supramolecular LHS with two-step energy transfer by using [2,2]paracyclophane-based double helicate metallacycles as donor (Fig. 7(b)).¹¹¹ These metallacycles displayed remarkable AIE effects and formed NPs in H₂O/THF (f_w = 90%) solvent mixture. By loading ESY and NiR as sequential energy-harvesting acceptors, the metallacycle-based LHS achieved an energy transfer efficiency of up to 89.3%. Furthermore, the authors constructed white-light emitting devices by coating these LHS materials on blue LED bulbs. This work suggests that double helicate metallacycles hold significant potential for optoelectronic devices.

Metallacages represent another significant class of supramolecular metal coordination complexes. Their cavity structure allows for the encapsulation of acceptor dyes, effectively preventing self-aggregation and offering a novel approach to creating efficient artificial LHSs and constructing supramolecular luminescent materials. In 2019, Zhang and co-workers prepared two tetragonal prismatic platinum(II) cages (4a and 4b) based on TPE (Fig. 7(c)).¹¹² Due to its good solubility in water, the cage 4b, which has eight polyethylene glycol (PEG) chains, was selected as energy donor, with ESY as the energy acceptor, to construct an LHS in water. In the cross-coupling hydrogen evolution reaction between benzothiazole and diphenylphosphine oxide, the LHS demonstrated significantly enhanced photocatalytic activity compared to ESY alone. This work highlights the potential of metallacages as light-harvesting catalysts for the efficient catalysis of organic reactions. In a follow-up work, Xu, Feng, and co-workers reported a supramolecular LHS based on a trigonal platinum(II) metallacage and NiR.¹¹⁵ Furthermore, Mukherjee and co-workers prepared prismatic molecular cages via coordination-driven self-assembly of a tetra-imidazole ligand and di-platinum(II) acceptors for constructing LHSs for oxidative cyclization.¹¹⁶

In recent years, beyond platinum coordination, other metal-coordinated metallacages have also been employed to construct LHSs. For example, in 2023, He and co-workers developed a highly emissive cage, Zn-1, formed by the self-assembly of zinc ions and a TPE-derived ligand M2 (Fig. 7(d)).¹¹³ This cage can encapsulate acceptor dyes such as ESY or SR101, bringing the donor and acceptor in close proximity and enabling highly efficient FRET between them. The Zn-1⊃ESY LHS achieved an energy transfer efficiency up to 82.4%, demonstrating its effectiveness as a light-harvesting photocatalyst for the dehalogenation of α-bromoacetophenone. Additionally, bright white light emission was achieved at CIE coordinates (0.32, 0.33) by adjusting the D/A molar ratio in another LHS Zn-1⊃SR101. This study illustrates a promising approach to enhancing energy transfer efficiency by encapsulating dye acceptors into metallacages, which serve as excellent platforms for mimicking natural LHSs. In subsequent work, the same team further constructed a metallacage based on the self-assembly of Ga³⁺ and TPE ligands, which was used to fabricate LHSs for photocatalytic aerobic reactions.¹¹⁷

Compared with the aforementioned discrete metallacycles and metallacages, supramolecular coordination polymers possess high surface area, ordered porosity, and superior stability, making them ideal scaffolds for designing supramolecular LHSs. In this context, Mukherjee and co-workers constructed a TPE-based Pt(II) coordination polymer through a two-component coordination-driven self-assembly between a TPE-based tetraimidazole donor (M3) and a 180° trans-[Pt-(PEt₃)₂(OTf)₂] acceptor (Fig. 7(e)).¹¹⁴M3 exhibited significant emission enhancement in water/DMSO mixture (f_w = 90%) as it further self-assembled into NPs. Due its porous structure, M3 was able to encapsulate organic dyes, forming LHSs. Consequently, ESY and NiR were selected as energy acceptors to achieve efficient sequential two-step FRET. Upon titration of ESY, the fluorescence band of M3 at 485 nm significantly decreased, while the fluorescence peak at 553 nm increased noticeably. Concurrently, the fluorescence color of the solution changed from blue to faint yellow, which was also confirmed from the 1931 CIE chromaticity diagram. When the excitation energy was further absorbed by NiR, the emission color transitioned from yellow to pink. The energy transfer efficiencies of the first and second steps were achieved to 58.8% and 68.5%, respectively.

6. LHSs based on multiple non-covalent interactions

The aforementioned LHSs primarily utilize typical non-covalent interactions as the main driving force for self-assembly. However, in some systems, LHS is driven by multiple supramolecular interactions. In this section, we focus on these LHSs constructed through multiple interactions. For instance, X.-Q. Wang, W. Wang, Yang, and co-workers successfully synthesized a novel class of AIEgen branched rotaxane dendrimers using AIEgen-functionalized [2]rotaxanes as raw materials (Fig. 8(a)).¹¹⁸ They employed a controlled divergence method based on metal coordination to construct efficient LHS. The macrocyclic molecule in the rotaxane is pillar[5]arene. The synthesized AIE macromolecules feature TPE groups at the tail of each dendritic structure, with a total of 21 TPE groups incorporated (TG3). The introduction of MeOH as a poor solvent not only induces movement of the dendritic molecular backbone but also initiates the aggregation process, resulting in emission enhancement and providing a foundation for efficient light harvesting. Subsequently, ESY was incorporated into the donor assembly to act as an energy acceptor, facilitating energy harvesting from the dendritic macromolecules. These LHSs demonstrated high efficiency as photocatalysts for photooxidation and aerobic CDC reactions, with LHSs based on higher generation TPE branched rotaxane dendrimers exhibiting enhanced catalytic performance. This work not only achieved the synthesis of AIEgen branched dendrimers but also showed a good platform for constructing LHSs for photocatalysis. Similarly, Hu, Xu, and co-workers recently developed an efficient hierarchical self-assembly strategy based on pillar[5]arene host–guest interaction and metal coordination to construct LHSs with two-step FRET.¹¹⁹

Artificial systems for chirality amplification and sequential energy transfer have received significant attention. However, the fabrication of chiral supramolecular LHSs remains a substantial challenge. Recently, Zheng, Zang, and co-workers constructed novel chiral LHSs with sequential energy transfer, wherein a blue-violet-emitting BINOL compound (BDA) acts as an initiator of chirality and a light-harvesting antenna (Fig. 8(b)).¹²⁰ Additionally, a hexagonal TPE-based macrocycle (TPEM) was synthesized to function as a relay acceptor, and either NiR or TPESe served as the final energy acceptors. Consequently, a sequential LHS with three components was successfully prepared, and chirality transmission/amplification along the cascaded energy transfer pathway was achieved. This resulted in intense, tailored color circularly polarized luminescence (CPL) and white-light emission with an amplified g_lum of 3.5 × 10⁻². This work paves a new way for mimicking natural chiral LHSs and demonstrates potential applications in CPL-related fields such as CPL switching, circularly polarized organic light-emitting diodes (CP-OLEDs), and optical encryption.

Platinum(II) metallacycle-based host–guest systems present significant opportunities for creating novel materials with diverse functions and structures, owing to their well-defined cavity sizes. In this context, Shi, Sun, Stang, and co-workers reported a [2]rotaxane assembled from a dumbbell-shaped guest molecule with TPE stoppers (M4) and a platinum(II) metallacycle-based host molecule (M5) (Fig. 8(c)).¹²¹ The [2]rotaxane was constructed using a template-directed clipping approach. Furthermore, the authors applied this [2]rotaxane to the construction of a supramolecular LHS with two-step FRET process. The [2]rotaxane M4–M5 further self-assembled into NPs in water/acetone mixture (f_w = 90%). ESY and NiR, serving as relay and final acceptors respectively, were incorporated into the NPs to achieve a sequential LHS. This study significantly contributes addition to macrocycle-based host–guest chemistry and demonstrates a method for the efficient preparation of well-defined mechanically interlocked molecules with practical application value.

7. Conclusions and perspectives

In summary, the utilization of tetraphenylethylene (TPE) chromophores as antennas in supramolecular light-harvesting systems (LHS) is a burgeoning field with vast potential. Meticulous molecular design and strategic assembly have enabled the creation of intricate architectures for efficient light absorption, energy transfer, and emission modulation. The unique AIE properties of TPE, along with strong hydrophobic interactions, endow these assemblies with remarkable photophysical characteristics, making them promising candidates for diverse applications. This Feature Article highlights the various strategies for designing and synthesizing TPE-based supramolecular assemblies, from covalent conjugation to non-covalent self-assembly. Understanding energy transfer mechanisms, including electron migration and FRET, provides insights into their photophysical behaviors, guiding the rational design of next-generation LHSs with tailored properties.

Although supramolecular TPE-based LHSs have made significant progress, several challenges remain for future development: (1) the range of energy acceptors for reported TPE-based LHSs is currently limited, with ESY or NiR frequently used. To accommodate a broader spectrum of applications, developing and identifying a wider array of matching donor–acceptor pairs is necessary. (2) Most examples discussed in this article involve one-step or two-step FRET systems. To further enhance energy capture and utilization, developing three-step or four-step energy transfer systems is more challenging and a crucial direction for future research. (3) While these reported LHSs have demonstrated some preliminary applications, further efforts are required to scale up production and achieve significant industrial applications.

Nevertheless, continued exploration of TPE-based supramolecular assemblies holds promise in the future for addressing pressing societal challenges such as energy sustainability, photocatalysis, and environmental remediation. By exploiting the synergy between molecular design, assembly strategies, and photophysical properties, researchers can unlock new functionalities and applications in areas ranging from solar energy conversion to molecular sensing. The convergence of supramolecular self-assembly and light harvesting has tremendous potential to drive innovation and shape the future of optoelectronics. As we embark on this journey of exploration, we will witness exciting breakthroughs and transformative advances in the field of TPE-based supramolecular LHSs.

Data availability

No new data were generated or analysed as part of this Feature Article.

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

T. X. acknowledges the National Natural Science Foundation of China (21702020). Q. Z. acknowledges the Postgraduate Research & Practice Innovation Program of Jiangsu Province (grant no. KYCX24_3184).

Notes and references

1. J. Lv, J. Xie, A. G. A. Mohamed, X. Zhang, Y. Feng, L. Jiao, E. Zhou, D. Yuan and Y. Wang, Nat. Rev. Chem., 2023, 7, 91–105 CrossRef PubMed .
2. R. Croce and H. van Amerongen, Science, 2020, 369, 2058 CrossRef .
3. C. Greening and T. Lithgow, Nat. Rev. Microbiol., 2020, 18, 677–689 CrossRef CAS .
4. A. Stirbet, D. Lazár, Y. Guo and G. Govindjee, Ann. Bot., 2019, 126, 511–537 CrossRef PubMed .
5. J.-Q. Cai, X.-M. Liu, Z.-J. Gao, L.-L. Li and H. Wang, Mater. Today, 2021, 45, 77–92 CrossRef CAS .
6. M. Griffiths, W. R. Sistrom, G. Cohen-Bazire and R. Y. Stanier, Nature, 1955, 176, 1211–1214 CrossRef CAS PubMed .
7. S. Guo, Y. Song, Y. He, X. Y. Hu and L. Wang, Angew. Chem., Int. Ed., 2018, 57, 3163–3167 CrossRef CAS PubMed .
8. P.-Z. Chen, Y.-X. Weng, L.-Y. Niu, Y.-Z. Chen, L.-Z. Wu, C.-H. Tung and Q.-Z. Yang, Angew. Chem., Int. Ed., 2016, 55, 2759–2763 CrossRef CAS PubMed .
9. Z. Wu, H. Qian, X. Li, T. Xiao and L. Wang, Chin. Chem. Lett., 2024, 35, 108829 CrossRef CAS .
10. D. Bokotial, K. Acharyya, A. Chowdhury and P. S. Mukherjee, Angew. Chem., Int. Ed., 2024, 63, e202401136 CrossRef CAS .
11. K. Wang, Y. Shen, P. Jeyakkumar, Y. Zhang, L. Chu, R. Zhang and X.-Y. Hu, Curr. Opin. Green Sustainable Chem., 2023, 41, 100823 CrossRef CAS .
12. X. M. Chen, X. Chen, X. F. Hou, S. Zhang, D. Chen and Q. Li, Nanoscale Adv., 2023, 5, 1830–1852 RSC .
13. Y. Wang, N. Han, X. Li, S. Yu and L. Xing, ChemPhysMater, 2022, 1, 281–293 CrossRef .
14. K. Wang, K. Velmurugan, B. Li and X. Y. Hu, Chem. Commun., 2021, 57, 13641–13654 RSC .
15. T. Xiao, W. Zhong, L. Zhou, L. Xu, X.-Q. Sun, R. B. P. Elmes, X.-Y. Hu and L. Wang, Chin. Chem. Lett., 2019, 30, 31–36 CrossRef CAS .
16. J. Otsuki, J. Mater. Chem. A, 2018, 6, 6710–6753 RSC .
17. Z. Sun, L. Zhu, J. Liu, F. Liu, P. Wu, P. Sui, H. Jin and S. Lin, Sci. China: Chem., 2024, 67, 1680–1686 CrossRef CAS .
18. C.-Y. Ding, Y.-W. Zhong and J. Yao, CCS Chem., 2024, 1–14 Search PubMed .
19. X.-Y. Hu and W. Wu, Curr. Opin. Green Sustainable Chem., 2023, 44, 100865 CrossRef .
20. K. Wang, X. Tian, J. H. Jordan, K. Velmurugan, L. Wang and X.-Y. Hu, Chin. Chem. Lett., 2022, 33, 89–96 CrossRef CAS .
21. W. Qian, M. Zuo, P. Niu, X.-Y. Hu and L. Wang, Chin. Chem. Lett., 2022, 33, 1975–1978 CrossRef CAS .
22. W. R. Algar, N. Hildebrandt, S. S. Vogel and I. L. Medintz, Nat. Methods, 2019, 16, 815–829 CrossRef CAS PubMed .
23. Y. Long, Y. Stahl, S. Weidtkamp-Peters, M. Postma, W. Zhou, J. Goedhart, M.-I. Sánchez-Pérez, T. W. J. Gadella, R. Simon, B. Scheres and I. Blilou, Nature, 2017, 548, 97–102 CrossRef CAS PubMed .
24. X. Qin, M. Suga, T. Kuang and J.-R. Shen, Science, 2015, 348, 989–995 CrossRef CAS .
25. D. Chen, T. Xiao, É. Monflier and L. Wang, Commun. Chem., 2024, 7, 88 CrossRef CAS PubMed .
26. F. Würthner, Angew. Chem., Int. Ed., 2020, 59, 14192–14196 CrossRef PubMed .
27. Y. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Soc. Rev., 2011, 40, 5361–5388 RSC .
28. Y.-X. Hu, W.-J. Li, P.-P. Jia, X.-Q. Wang, L. Xu and H.-B. Yang, Adv. Opt. Mater., 2020, 8, 2000265 CrossRef CAS .
29. J. G. Yu, L. Y. Sun, C. Wang, Y. Li and Y. F. Han, Chem. – Eur. J., 2021, 27, 1556–1575 CrossRef CAS PubMed .
30. K. Fu, X. Zeng, X. Zhao, Y. Wu, M. Li, X. S. Li, C. Pan, Z. Chen and Z. Q. Yu, Small, 2021, 17, e2103172 CrossRef PubMed .
31. M. L. Saha, X. Yan and P. J. Stang, Acc. Chem. Res., 2016, 49, 2527–2539 CrossRef CAS PubMed .
32. H. Nie, Z. Wei, X.-L. Ni and Y. Liu, Chem. Rev., 2022, 122, 9032–9077 CrossRef CAS PubMed .
33. X. Y. Lou and Y. W. Yang, Aggregate, 2020, 1, 19–30 CrossRef .
34. X. Ma, J. Wang and H. Tian, Acc. Chem. Res., 2019, 52, 738–748 CrossRef CAS PubMed .
35. Z. Xu, S. Peng, Y. Y. Wang, J. K. Zhang, I. Lazar Alexandra and D. S. Guo, Adv. Mater., 2016, 28, 7666–7671 CrossRef CAS PubMed .
36. S. Hirayama, K. Oohora, T. Uchihashi and T. Hayashi, J. Am. Chem. Soc., 2020, 142, 1822–1831 CrossRef CAS PubMed .
37. X. Y. Dai, M. Huo, X. Y. Dong, Y. Y. Hu and Y. Liu, Adv. Mater., 2022, 34, e2203534 CrossRef .
38. M. Li, Q. Y. Shi, N. X. Song, Z. J. Chen, L. D. Wang and T. D. James, Adv. Opt. Mater., 2023, 11, 2203079 CrossRef CAS .
39. J. J. Li, Y. Chen, J. Yu, N. Cheng and Y. Liu, Adv. Mater., 2017, 29, 1701905 CrossRef PubMed .
40. H.-J. Kim, P. C. Nandajan, J. Gierschner and S. Y. Park, Adv. Funct. Mater., 2018, 28, 1705141 CrossRef .
41. D. Chen, C. Bao, L. Zhang, Q. Zhang, Z. Wu, Z. Y. Li, X. Q. Sun, L. Wang and T. Xiao, Adv. Funct. Mater., 2024, 34, 2314093 CrossRef CAS .
42. G. Sun, M. Zuo, W. Qian, J. Jiao, X.-Y. Hu and L. Wang, Green Synth. Catal., 2021, 2, 32–37 CrossRef .
43. G. Sun, M. Li, L. Cai, J. Zhu, Y. Tang and Y. Yao, Chem. Commun., 2024, 60, 1412–1415 RSC .
44. Y. Han, X. Zhang, Z. Ge, Z. Gao, R. Liao and F. Wang, Nat. Commun., 2022, 13, 3546 CrossRef CAS PubMed .
45. P. P. Jia, L. Xu, Y. X. Hu, W. J. Li, X. Q. Wang, Q. H. Ling, X. Shi, G. Q. Yin, X. Li, H. Sun, Y. Jiang and H. B. Yang, J. Am. Chem. Soc., 2021, 143, 399–408 CrossRef CAS PubMed .
46. Y. Li, S. S. Rajasree, G. Y. Lee, J. Yu, J.-H. Tang, R. Ni, G. Li, K. N. Houk, P. Deria and P. J. Stang, J. Am. Chem. Soc., 2021, 143, 2908–2919 CrossRef CAS PubMed .
47. H. Qian, T. Xiao, R. B. P. Elmes and L. Wang, Chin. Chem. Lett., 2023, 34, 108185 CrossRef CAS .
48. S. Yu, R.-X. Zhu, K.-K. Niu, N. Han, H. Liu and L.-B. Xing, Chem. Sci., 2024, 15, 1870–1878 RSC .
49. P. K. Dutta, R. Varghese, J. Nangreave, S. Lin, H. Yan and Y. Liu, J. Am. Chem. Soc., 2011, 133, 11985–11993 CrossRef CAS PubMed .
50. Q. Song, S. Goia, J. Yang, S. C. L. Hall, M. Staniforth, V. G. Stavros and S. Perrier, J. Am. Chem. Soc., 2021, 143, 382–389 CrossRef CAS PubMed .
51. R. Biswas and S. Banerjee, J. Phys. Chem. B, 2023, 127, 4135–4144 CrossRef CAS PubMed .
52. X. He, S. Zhang, S. Qi, P. Xu, B. Dong and B. Song, Dyes Pigm., 2023, 209, 110933 CrossRef CAS .
53. K. Yang, Z. Zhang, J. Du, W. Li and Z. Pei, Chem. Commun., 2020, 56, 5865–5876 RSC .
54. H. Zhu, L. Chen, B. Sun, M. Wang, H. Li, J. F. Stoddart and F. Huang, Nat. Rev. Chem., 2023, 7, 768–782 CrossRef CAS PubMed .
55. K. Kato, S. Fa, S. Ohtani, T. H. Shi, A. M. Brouwer and T. Ogoshi, Chem. Soc. Rev., 2022, 51, 3648–3687 RSC .
56. J.-R. Wu, G. Wu and Y.-W. Yang, Acc. Chem. Res., 2022, 55, 3191–3204 CrossRef CAS PubMed .
57. H. Zhu, Q. Li, W. Zhu and F. Huang, Acc. Mater. Res., 2022, 3, 658–668 CrossRef CAS .
58. L.-B. Meng, D. Li, S. Xiong, X.-Y. Hu, L. Wang and G. Li, Chem. Commun., 2015, 51, 4643–4646 RSC .
59. T. Xiao, H. Qian, Y. Shen, C. Wei, D. Ren, L. Zhang, Z. Y. Li, L. Wang and X. Q. Sun, Mater. Today Chem., 2022, 24, 100833 CrossRef CAS .
60. X. Li, Z. Wu, Q. Wang, Z.-Y. Li, X.-Q. Sun and T. Xiao, ChemPlusChem, 2023, 88, e202300431 CrossRef CAS PubMed .
61. X. H. Wang, N. Song, W. Hou, C. Y. Wang, Y. Wang, J. Tang and Y. W. Yang, Adv. Mater., 2019, 31, e1903962 CrossRef PubMed .
62. L. Xu, Z. Wang, R. Wang, L. Wang, X. He, H. Jiang, H. Tang, D. Cao and B. Z. Tang, Angew. Chem., Int. Ed., 2020, 59, 9908–9913 CrossRef CAS PubMed .
63. J. J. Li, H. Y. Zhang, X. Y. Dai, Z. X. Liu and Y. Liu, Chem. Commun., 2020, 56, 5949–5952 RSC .
64. T. Xiao, H. Qian, X. Li, Z. Wu, Z.-Y. Li and X.-Q. Sun, Dyes Pigm., 2023, 215, 111289 CrossRef CAS .
65. L. Xu, R. Wang, H. Tang, L. Wang and D. Cao, J. Mater. Chem. A, 2022, 10, 11332–11339 RSC .
66. M. Hao, G. Sun, M. Zuo, Z. Xu, Y. Chen, X. Y. Hu and L. Wang, Angew. Chem., Int. Ed., 2020, 59, 10095–10100 CrossRef CAS PubMed .
67. T. Xiao, D. Chen, H. Qian, Y. Shen, L. Zhang, Z.-Y. Li and X.-Q. Sun, Dyes Pigm., 2023, 210, 110958 CrossRef CAS .
68. T. Xiao, L. Zhang, D. Chen, Q. Zhang, Q. Wang, Z.-Y. Li and X.-Q. Sun, Org. Chem. Front., 2023, 10, 3245–3251 RSC .
69. X. Tian, S. Li, K. Velmurugan, Z. Bai, Q. Liu, K. Wang, M. Zuo and X.-Y. Hu, Mater. Chem. Front., 2023, 7, 2484–2492 RSC .
70. K. Kim, Chem. Soc. Rev., 2002, 31, 96–107 RSC .
71. S. J. Barrow, S. Kasera, M. J. Rowland, J. del Barrio and O. A. Scherman, Chem. Rev., 2015, 115, 12320–12406 CrossRef CAS PubMed .
72. W. Zhang, Y. Luo, X.-L. Ni, Z. Tao and X. Xiao, Chem. – Eur. J., 2022, 446, 136954 CAS .
73. X.-L. Li, Y. Wang, M.-H. Zhang, M. Jiang, H. Liu, R.-Z. Wang, S. Yu and L.-B. Xing, Dyes Pigm., 2022, 197, 109895 CrossRef CAS .
74. Y. Liu, M. Zhou, Y. Liu, X. Han, X. Zhang and S. Liu, Supramol. Chem., 2020, 32, 445–451 CrossRef CAS .
75. F. Qiao, Z. Yuan, Z. Lian, C.-Y. Yan, S. Zhuo, Z.-Y. Zhou and L.-B. Xing, Dyes Pigm., 2017, 146, 392–397 CrossRef CAS .
76. Y. Li, Q. Li, X. Miao, C. Qin, D. Chu and L. Cao, Angew. Chem., Int. Ed., 2021, 60, 6744–6751 CrossRef CAS PubMed .
77. K. D. Zhang, J. Tian, D. Hanifi, Y. Zhang, A. C. Sue, T. Y. Zhou, L. Zhang, X. Zhao, Y. Liu and Z. T. Li, J. Am. Chem. Soc., 2013, 135, 17913–17918 CrossRef CAS PubMed .
78. Y. Wang, C. Q. Ma, X. L. Li, R. Z. Dong, H. Liu, R. Z. Wang, S. S. Yu and L. B. Xing, J. Mater. Chem. A, 2023, 11, 2627–2633 RSC .
79. R. Cen, M. Liu, J.-H. Lu, Z. Tao and X. Xiao, ACS Appl. Mater. Interfaces, 2024, 16, 13132–13138 CrossRef CAS PubMed .
80. Q. Liu, M. Z. Zuo, K. Y. Wang and X. Y. Hu, Chem. Commun., 2023, 59, 13707–13710 RSC .
81. J. Jiao, G. Sun, J. Zhang, C. Lin, J. Jiang and L. Wang, Chem. – Eur. J., 2021, 27, 16601–16605 CrossRef CAS PubMed .
82. T. Xiao, L. Zhou, X.-Q. Sun, F. Huang, C. Lin and L. Wang, Chin. Chem. Lett., 2020, 31, 1–9 CrossRef CAS .
83. T. Xiao, L. Xu, J. Götz, M. Cheng, F. Würthner, J. Gu, X. Feng, Z.-Y. Li, X.-Q. Sun and L. Wang, Mater. Chem. Front., 2019, 3, 2738–2745 RSC .
84. R. P. Sijbesma and E. W. Meijer, Chem. Commun., 2003, 5–16 RSC .
85. H. Q. Peng, J. F. Xu, Y. Z. Chen, L. Z. Wu, C. H. Tung and Q. Z. Yang, Chem. Commun., 2014, 50, 1334–1337 RSC .
86. K.-X. Teng, Z.-P. An, L.-Y. Niu and Q.-Z. Yang, ACS Mater. Lett., 2024, 6, 290–297 CrossRef CAS .
87. T. Xiao, Y. Shen, C. Bao, K. Diao, D. Ren, H. Qian and L. Zhang, RSC Adv., 2021, 11, 30041–30045 RSC .
88. T. Xiao, L. Zhang, H. Wu, H. Qian, D. Ren, Z.-Y. Li and X.-Q. Sun, Chem. Commun., 2021, 57, 5782–5785 RSC .
89. X. Zhu, J. X. Wang, L. Y. Niu and Q. Z. Yang, Chem. Mater., 2019, 31, 3573–3581 CrossRef CAS .
90. Z. Lian, F. Qiao, M. Jiang, R.-Z. Wang, L.-B. Xing, S. Liu and S. Wang, Dyes Pigm., 2019, 171, 107774 CrossRef CAS .
91. T. Xiao, H. Wu, G. Sun, K. Diao, X. Wei, Z.-Y. Li, X.-Q. Sun and L. Wang, Chem. Commun., 2020, 56, 12021–12024 RSC .
92. L. Zhang, H. Qian, Z. Wu, Q. Zhang, S. Li, M. Cheng and T. Xiao, Molecules, 2022, 27, 8876 CrossRef CAS PubMed .
93. Y. Li, Y. Dong, L. Cheng, C. Qin, H. Nian, H. Zhang, Y. Yu and L. Cao, J. Am. Chem. Soc., 2019, 141, 8412–8415 CrossRef CAS PubMed .
94. T. Xiao, C. Bao, L. Zhang, K. Diao, D. Ren, C. Wei, Z.-Y. Li and X.-Q. Sun, J. Mater. Chem. A, 2022, 10, 8528–8534 RSC .
95. Z. Wang, X. He, T. Yong, Y. Miao, C. Zhang and B. Zhong Tang, J. Am. Chem. Soc., 2020, 142, 512–519 CrossRef CAS PubMed .
96. L. Tang, Z. Wu, Q. Zhang, Q. Hu, X. Dang, F. Cui, L. Tang and T. Xiao, Chem. Commun., 2024, 60, 4719–4722 RSC .
97. Z. Wu, Q. Zhang, D. Chen and T. Xiao, Sens. Diagn., 2024, 3, 295–300 RSC .
98. T. Xiao, X. Wei, H. Wu, K. Diao, Z.-Y. Li and X.-Q. Sun, Dyes Pigm., 2021, 188, 109161 CrossRef CAS .
99. X. Fan, C. P. Teng, J. C. C. Yeo, Z. Li, T. Wang, H. Chen, L. Jiang, X. Hou, C. He and J. Liu, Macromol. Rapid Commun., 2021, 42, 2000716 CrossRef CAS PubMed .
100. C. Li, J. Zhang, S. Zhang and Y. Zhao, Angew. Chem., Int. Ed., 2019, 58, 1643–1647 CrossRef CAS PubMed .
101. M. Zhang, X. Yin, T. Tian, Y. Liang, W. Li, Y. Lan, J. Li, M. Zhou, Y. Ju and G. Li, Chem. Commun., 2015, 51, 10210–10213 RSC .
102. T. Xiao, L. Tang, D. Ren, K. Diao, Z.-Y. Li and X.-Q. Sun, Chem. – Eur. J., 2023, 29, e202203463 CrossRef CAS PubMed .
103. T. Xiao, D. Ren, L. Tang, Z. Wu, Q. Wang, Z.-Y. Li and X.-Q. Sun, J. Mater. Chem. A, 2023, 11, 18419–18425 RSC .
104. D. Ren, L. Tang, Z. Wu, Q. Zhang, T. Xiao, R. B. P. Elmes and L. Wang, Chin. Chem. Lett., 2023, 34, 108617 CrossRef CAS .
105. T. Xiao, D. Ren, K. Diao, J. Wang, Z. Y. Li, X. Q. Sun and L. Wang, Chem. – Asian J., 2022, 17, e202200386 CrossRef CAS PubMed .
106. H. Y. Lin, Y. T. Wang, X. Shi, H. B. Yang and L. Xu, Chem. Soc. Rev., 2023, 52, 1129–1154 RSC .
107. R. Chakrabarty, P. S. Mukherjee and P. J. Stang, Chem. Rev., 2011, 111, 6810–6918 CrossRef CAS PubMed .
108. A. Sautter, B. K. Kaletaş, D. G. Schmid, R. Dobrawa, M. Zimine, G. Jung, I. H. M. van Stokkum, L. De Cola, R. M. Williams and F. Würthner, J. Am. Chem. Soc., 2005, 127, 6719–6729 CrossRef CAS PubMed .
109. D. Zhang, W. Yu, S. Li, Y. Xia, X. Li, Y. Li and T. Yi, J. Am. Chem. Soc., 2021, 143, 1313–1317 CrossRef CAS PubMed .
110. D. Zhang, M. Li, B. Jiang, S. Liu, J. Yang, X. Yang, K. Ma, X. Yuan and T. Yi, J. Colloid Interface Sci., 2023, 652, 1494–1502 CrossRef CAS PubMed .
111. Z. Lian, J. He, L. Liu, Y. Fan, X. Chen and H. Jiang, Nat. Commun., 2023, 14, 2752 CrossRef CAS PubMed .
112. Z. Zhang, Z. Zhao, Y. Hou, H. Wang, X. Li, G. He and M. Zhang, Angew. Chem., Int. Ed., 2019, 58, 8862–8866 CrossRef CAS PubMed .
113. D. Li, X. Liu, L. Yang, H. Li, G. Guo, X. Li and C. He, Chem. Sci., 2023, 14, 2237–2244 RSC .
114. S. Ahmed, A. Kumar and P. S. Mukherjee, Chem. Mater., 2022, 34, 9656–9665 CrossRef CAS .
115. N. Wang, W. Yang, L. Feng, X. D. Xu and S. Feng, Dalton Trans., 2023, 52, 15524–15529 RSC .
116. A. Kumar, R. Saha and P. S. Mukherjee, Chem. Sci., 2021, 12, 5319–5329 RSC .
117. D. Li, L. Yang, W. Fang, X. Fu, H. Li, J. Li, X. Li and C. He, Chem. Sci., 2023, 14, 9943–9950 RSC .
118. W. J. Li, X. Q. Wang, D. Y. Zhang, Y. X. Hu, W. T. Xu, L. Xu, W. Wang and H. B. Yang, Angew. Chem., Int. Ed., 2021, 60, 18761–18768 CrossRef CAS PubMed .
119. P.-P. Jia, L. Hu, W.-T. Dou, X.-D. Xu, H. Sun, Z.-Y. Peng, D.-Y. Zhang, H.-B. Yang and L. Xu, J. Mater. Chem. C, 2023, 11, 6607–6615 RSC .
120. Y. X. Yuan, J. H. Jia, Y. P. Song, F. Y. Ye, Y. S. Zheng and S. Q. Zang, J. Am. Chem. Soc., 2022, 144, 5389–5399 CrossRef CAS PubMed .
121. B. Shi, X. Li, Y. Chai, P. Qin, Y. Zhou, W.-J. Qu, Q. Lin, T.-B. Wei, Y. Sun and P. J. Stang, Angew. Chem., Int. Ed., 2023, 62, e202305767 CrossRef PubMed .

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