Construction Of Artificial Light-harvesting Systems Research Articles

Construction of artificial light-harvesting system based on host-guest interactions of sulfobutylether-β-cyclodextrin and its application in photocatalysis

Light-harvesting systems (LHSs) play an important role in natural photosynthesis for converting light energy into chemical energy, which paves a prospective way for the exploitation of renewable energy resources. In this work, two artificial light-harvesting systems with an efficient energy transfer were constructed successfully in the aqueous media based on sulfobutylether-β-cyclodextrin (β-CD) and curcumin (Cur) through host-guest interactions, in which two different fluorescence dyes, sulforhodamine (SR101) and Nile blue (NiB) were employed as energy acceptors. The obtained artificial LHSs can achieve an efficient energy transfer process from β-CD+Cur to SR101 or NiB with energy transfer efficiencies of up to 16.3% and 15.8%, respectively. The energy harvested by the acceptors (SR101 and NiB) was used for photocatalysis in the aqueous phase dehalogenation of the α-bromoacetophenone reaction with a yield of up to 80%.

Construction of aggregation-induced emission photosensitizers through host-guest interactions for photooxidation reaction and light-harvesting

In the present work, we have designed and synthesized a triphenylamine modified cyanophenylenevinylene derivative (TPCI), which can self-assembly with cucurbit[6]uril (CB[6]) and cucurbit[8]uril (CB[8]) through host-guest interactions to form supramolecular complexes (TPCI-CB[6]) and supramolecular polymers (TPCI-CB[8]) in the aqueous solution. The supramolecular assemblies of TPCI-CB[6] and TPCI-CB[8] not only exhibited high singlet oxygen (1O2) production efficiency as photosensitizers, but also realized the application in the construction of artificial light-harvesting systems due to the excellent fluorescence properties in the aqueous solution. The production efficiency of 1O2 has been effectively improved after the addition of CB[6] and CB[8] for TPCI, which were applied as efficient photosensitizers in the photooxidation reactions of thioanisole and its derivatives with the highest yield of 98% in the aqueous solution. The excellent fluorescence properties of TPCI-CB[6] and TPCI-CB[8] can be used as energy donors in artificial light-harvesting systems with energy acceptors sulforhodamine 101 (SR101) and cyanine dye 5 (Cy5), in which one-step energy transfer processes of TPCI-CB[6]+SR101 and TPCI-CB[8]+Cy5, and a two-step sequential energy transfer process of TPCI-CB[6]+SR101+Cy5 were constructed to simulate the natural photosynthesis system.

Construction of Artificial Light-Harvesting Systems Based on Aggregation-Induced Emission Type Supramolecular Self-Assembly Metallogels.

A method for preparing new artificial light-harvesting systems (ALHSs) based on supramolecular metallogels was proposed. Various metal ions were introduced into a solution of a bi-benzimidazole compound (P) in ethylene glycol, and P exhibited high selectivity toward Al3+, as indicated by the noticeable red shift (49 nm) observed in the fluorescence spectra of P after the addition of Al3+. Interestingly, the gelator, P, could self-assemble into a stable supramolecular gel (P-gel) that exhibits strong aggregation-induced emission in ethylene glycol. Thus, two ALHSs were successfully prepared in a gel environment. The P-Al3+ assembly acts as the donor in the ALHSs, while BODIPY 505/515 (BDP) and rhodamine 6G (Rh6G), which are loaded onto the P-Al3+ assembly, act as acceptors. In these two diverse systems, the occurrence of an energy transfer process is confirmed from the P-Al3+ assembly to BDP and Rh6G. The findings of this study will enable the design and fabrication of ALHSs.

A novel strategy of constructing an artificial light-harvesting system based on a supramolecular organic framework for photocatalysis

A supramolecular organic framework was fabricated through encapsulation-enhanced donor–acceptor interaction for the construction of artificial light-harvesting systems for photocatalysis.

Construction of artificial light-harvesting systems based on a variety of polyelectrolyte materials and application in photocatalysis

In the present work, we designed and synthesized a cationic cyano-substituted p-phenylenevinylene derivative (PPTA), which can form supramolecular assemblies through electrostatic interaction with a type of polyelectrolyte material anionic guar gum (GP5A). A polyelectrolyte-based artificial light-harvesting system (LHS) was constructed by selecting a fluorescent dye sulforhodamine 101 (SR101) that matched its energy level as an energy acceptor. The energy harvested by the acceptors was used in the aqueous phase cross dehydrogenation coupling (CDC) reaction with a yield of up to 87%. In addition, the general applicability of polyelectrolyte materials to build artificial LHS was demonstrated by three other polyelectrolyte materials sodium polyphenylene sulfonate (RSS), sodium carboxymethyl cellulose (CMC), and sodium polyacrylate (PAAS), in which the CDC reaction was also carried out by these three LHSs and obtained high yields. This work not only provides a new method to construct LHSs by using polyelectrolyte materials, but also provides a beneficial exploration for further applying the energy harvested in LHSs to the field of photocatalysis in an aqueous solution.

Construction of an Artificial Light-Harvesting System with Efficient Photocatalytic Activity in an Aqueous Solution Based on a FRET-Featuring Metallacage.

Over the past few decades, the design and construction of high-efficiency artificial light-harvesting systems (LHSs) involving multistep fluorescence-resonance energy transfer (FRET) processes have gradually received considerable attention within wide fields ranging from supramolecular chemistry to chemical biology and even materials science. Herein, through coordination-driven self-assembly, a novel tetragonal prismatic metallacage featuring a FRET process using tetraphenylethene (TPE) units as donors and BODIPY units as acceptors has been conveniently synthesized. Subsequently, taking advantage of supramolecular hydrophobic interactions, a promising artificial LHS involving two-step FRET processes from TPE to BODIPY and then to Nile Red (NiR) has been successfully fabricated in an aqueous solution using the FRET-featuring metallacage, NiR, and an amphiphilic polymer (mPEG-DSPE). Notably, this obtained aqueous LHS exhibits highly efficient photocatalytic activity in the dehalogenation of a bromoacetophenone derivate. This study provides a unique strategy for fabricating artificial LHSs in aqueous solutions with multistep FRET processes and further promotes the future development of mimicking the photosynthesis process.

Supramolecular polymers based on host-guest interactions for the construction of artificial light-harvesting systems

In the present work, artificial light-harvesting systems with a fluorescence resonance energy transfer (FRET) process were successfully obtained in the aqueous solution. We designed and synthesized an amphiphilic pyrene derivative with two 4-vinylpyridium arms (Pmvb), which can interact with cucurbit[8]uril (CB[8]) to form supramolecular polymer through host-guest interactions in aqueous solution. The formation of supramolecular polymers results in a significant enhancement of fluorescence, which makes Pmvb-CB[8] an ideal energy donor to construct artificial light-harvesting systems in the aqueous solution. Subsequently, two different fluorescence dyes Rhodamine B (RhB) and Sulforhodamine 101 (SR101) were introduced as energy acceptors into the solution of Pmvb-CB[8] respectively, to fabricate two different artificial light-harvesting systems. The obtained artificial light-harvesting systems can achieve an efficient energy transfer process from Pmvb-CB[8] to RhB or SR101 with high energy transfer efficiency.

Regulation of light-harvesting antenna based on silver ion-enhanced emission of dye-doped coordination polymer nanoparticles

The design and construction of artificial light-harvesting systems for solar energy conversion to chemical energy has been an active research field. A variety of molecules and materials have been used to mimic the function of the light-harvesting antenna. However, the improvement or regulation of the antenna effect of the existing artificial light-harvesting systems is less explored. Coordination polymers have aroused extensive concern due to their applications in light-harvesting and energy conversion. Herein, it is found that silver ion can dramatically enhance the emission of dye encapsulated in the coordination polymer nanoparticles (CPNs). The mechanism of Ag+-induced fluorescence enhancement is elucidated. Taking advantage of the effect of Ag+ ions, the regulation of CPN-based light-harvesting system by Ag+ is achieved for the first time. The antenna effect could be up to 2.3 times the original value by adding Ag+ ions. The present work provides a new approach to regulate the antenna effect of the light-harvesting system with the advantages of convenience, rapidity, low cost, and flexibility.

Construction of artificial light-harvesting systems in aqueous solution: Supramolecular polymers based on host-enhanced π–π interaction with aggregation-induced emission

In this work, we report a simple strategy by mixing a naphthyl-substituted 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA) and cucurbit[8]uril (CB[8]) in aqueous solution, based on the host-guest complexation between CB[8] and a BP4VA derivative (1), to construct supramolecular polymers. The host-guest interaction between CB[8] and naphthyl efficiently restricted the intramolecular rotation and the non-radiative relaxation channel, thereby resulting in the strong emission in dilute solution. We further investigate the self-assembly behaviors of the complex between CB[8] and 1. The aggregated species of the supramolecular polymers in aqueous solution exhibited nanorods structures with a relatively wide size distribution ranging from 60 to 200nm, which showed potential application as highly efficient aqueous light-harvesting systems by using supramolecular polymers as energy donor and sulfo-cyanine5 carboxylic acid (Cy5) as energy acceptor.

Substituent Effects of Porphyrin Monolayers on the Structure and Photoelectrochemical Properties of Self-Assembled Monolayers of Porphyrin on Indium−Tin Oxide Electrode

Self-assembled monolayers (SAMs) of porphyrins have been prepared to examine the substituent effects of porphyrin monolayers on the structure and photoelectrochemical properties of the SAMs on an ITO electrode. The ultraviolet (UV)−visible absorption, steady-state fluorescence, and cyclic voltammetry measurements for the porphyrin SAMs revealed that the interaction between the porphyrins without bulky tert-butyl groups is much larger than that of the porphyrins with bulky tert-butyl groups. Photoelectrochemical measurements were performed in nitrogen-saturated Na2SO4 aqueous solution containing triethanolamine as an electron sacrificer using the modified ITO working electrode, a platinum wire counter electrode, and an Ag/AgCl reference electrode. The internal quantum yields of photocurrent generation together with the porphyrin fluorescence lifetimes remain virtually the same irrespective of the steric hindrance, which is in sharp contrast with severe self-quenching of the porphyrin excited singlet state in conventional molecular assemblies such as Langmuir−Blodgett films. The two-dimensional, densely packed structure of the porphyrins in SAM is responsible for the long-lived excited singlet state, which is similar to the antenna function of photosystem I in cyanobacteria. These results will provide valuable information on the construction of artificial light-harvesting systems.