Carbazole-based artificial light-harvesting system for photocatalytic cross-coupling dehydrogenation reaction

Preparation of water-soluble imidazole-functionalized pillar[5]arenes: The activities of antibacterial and antioxidant, catalytic reduction of 4-nitrophenol

Macrocyclic supramolecular materials such as pillar[n]arenes play a prominent role in enhancing antibacterial activity through host-guest interactions. Herein, the water-soluble pillar[5]arene imidazole-1 and pillar[5]arene imidazole-2 were prepared, and their structure and chemical compositions were analyzed through multiple characterization methods. Afterward, the prepared imidazole-functionalized pillar[5]arenes were examined for antibacterial activity against Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and Salmonella typhimurium bacteria. Also, the antioxidant activities of the prepared imidazole-functionalized pillar[5]arenes were investigated using 2,2-Diphenyl-1-picrylhydrazyl. In addition, the catalytic activities of pillar[5]arene imidazole-1 and pillar[5]arene imidazole-2 by reduction of 4-nitrophenol were studied, indicating the catalytic reduction of 4-nitrophenol was 93.0 % for the pillar[5]arene imidazole-1 catalyst at 18 min. Comparison of the reactivity of pillar[5]arene imidazole-1 with that of pillar[5]arene imidazole-2 shows an increase in antibacterial and catalytic activity. This study summarized that using suitable catalysts, catalytic reduction aims to convert the most harmful and toxic organic compound 4-nitrophenol into non-toxic 4-aminophenol and popularize it in industry.

Enhanced emission in a supramolecular artificial light-harvesting system for a photocatalytic thiol-ene reaction

A novel supramolecular artificial light-harvesting system (LHS) was constructed through the host-guest assembly of water-soluble phosphate-pillar[5]arene (WPP5), AIE-enhanced donor (BND), and Eosin Y (ESY) acceptor. This LHS could significantly promote the photocatalytic thiol-ene click reaction of thiophenol and styrene derivatives.

Bis-Naphthylacrylonitrile-Based Supramolecular Artificial Light-Harvesting System for White Light Emission

A novel aggregation-induced emission (AIE)-based artificial light-harvesting system (LHS) is successfully assembled via the host-guest interaction of bis-naphthylacrylonitrile derivative (BND), water-soluble pillar[5]arene (WP5), and sulforhodamine 101 (SR101). After host-guest assembly, the formed WP5⊃BND complexes spontaneously self-aggregated into WP5⊃BND nanoparticles (donors) and SR101 (acceptors) is introduced into WP5⊃BND to fabricate WP5⊃BND-SR101 LHS. Through the investigation of energy transfer between donors and acceptors, the artificial light-harvesting processes are certified in WP5⊃BND-SR101 LHS and the absolute fluorescence quantum yields (Φf(abs)) are significantly improved from 8.9% (for WP5⊃BND) to 31.1% (for WP5⊃BND-SR101), exhibiting the excellent light-harvesting capabilities. Notably, by tuning the donor/acceptor (D:A) molar ratio to 250:1, a conspicuous white light emission (CIE coordinate is (0.32, 0.32)) is realized and the fluorescence quantum yield of white light emission (Φf(abs) WP5 ⊃ BND-SR101-White) is 29.2%. Moreover, the antenna effect of white fluorescence emission (AEWP5 ⊃ BND-SR101-White) can reach 36.2, which is higher than that of recent artificial LHSs in water environments, suggesting vast potential applications in aqueous LHSs.

Enhanced Emission in Polyelectrolyte Assemblies for the Development of Artificial Light-Harvesting Systems and Color-Tunable LED Device

Artificial light-harvesting systems (LHSs) are of growing interest for their potential in energy capture and conversion, but achieving efficient fluorescence in aqueous environments remains challenging. In this study, a novel tetraphenylethylene (TPE) derivative, TPEN, is synthesized and co-assembled with poly(sodium 4-styrenesulfonate) (PSS) to enhance its fluorescence via electrostatic interactions. The resulting PSS⊃TPEN network significantly increased blue emission, which is further harnessed by an energy-matched dye, 4,7-di(2-thienyl)benzo[2,1,3]thiadiazole (DBT), to produce an efficient LHS with yellow emission. Moreover, this system is successfully applied to develop color-tunable light-emitting diode (LED) devices. The findings demonstrate a cost-effective and environmentally friendly approach to designing tunable luminescent materials, with promising potential for future advancements in energy-efficient lighting technologies.

Supramolecular light-harvesting systems utilizing tetraphenylethylene chromophores as antennas

Efficient utilization of light energy is crucial for various technological applications ranging from solar energy conversion to optoelectronic devices. Supramolecular light-harvesting systems (LHS) have emerged as promising platforms for enhancing light absorption and energy transfer process. In this Feature Article, we highlight the utilization of tetraphenylethylene (TPE) chromophores as antennas in supramolecular assemblies for light harvesting applications. TPE, as an archetypal aggregation-induced emission (AIE) chromophore, offers unique advantages such as high photostability and efficient light-harvesting capabilities upon self-assembly. We discuss the design principles and synthetic strategies employed to construct supramolecular assemblies incorporating TPE chromophores, elucidating their roles as efficient light-harvesting antennas. Furthermore, we delve into the mechanisms governing energy transfer processes within these assemblies, such as Förster resonance energy transfer (FRET). The potential applications of these TPE-based supramolecular systems in various fields, including photocatalysis, reactive oxygen species generation, optoelectronic devices and sensing, are explored. Finally, we provide insights into future directions and challenges in the development of next-generation supramolecular LHSs utilizing TPE chromophores.

A supramolecular photosensitizer based on triphenylamine and pyrazine with aggregation-induced emission properties for high-efficiency photooxidation reactions

Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4'-(12-(pyridin-4-yl)dibenzo[f,h]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N,N-diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (ΔEST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O2, which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly.

Interfacial Charge Transfer in Photoexcited QD-Molecule Composite of Tetrahedral CdSe Quantum Dot Coupled with Carbazole

Photoexcited charge transfer dynamics in CdSe quantum dots (QDs) coupled with carbazole were explored to model QD-molecule systems for light-harvesting applications. The absorption spectra of QDs with different sizes, i.e., Cd35Se20X30L30 (T1), Cd56Se35X42L42 (T2), and Cd84Se56X56L56 (T3) were simulated with quantum dynamical methods, which qualitatively match the reported experimental spectra. The carbazole is attached with a 3-amino group at the apex position of T1 (namely T1-3A-Cz), establishing proper electronic communication between T1 and carbazole. The spectra of T1-3A-Cz is 0.22 eV red-shifted compared to T1. A time-dependent perturbation was applied in tune with the lowest energy peak (3.63 eV) of T1-3A-Cz to investigate the charge transfer dynamics, which revealed an ultrafast charge separation within the femtosecond time scale. The electronic structure showed a favorable energy alignment between T1 and carbazole in T1-3A-Cz. The LUMO of carbazole was situated below the conduction band of the QD, while the HOMO of carbazole mixed perfectly with the top of the valence band of the QD, developing the interfacial charge transfer states. These states promoted the photoexcited electron transfer directly from the CdSe core to carbazole. A rapid and enhanced charge separation occurred with the laser field strength increasing from 0.001 to 0.005 V/Å. However, T1 connected to the other positions of carbazole did not show charge separation effectively. The photoinduced charge transfer is negligible in the case of T2-carbazole systems due to poor electronic coupling, and it is not observed in T3-carbazole systems. So, the T1-3A-Cz model acts as a perfect donor-acceptor QD-molecule nanocomposite that can harvest photon energy efficiently. Further enhancement of charge transfer can be achieved by coupling more carbazoles to the T1 QD (e.g., T1-3A-Cz2) due to the extension of hole delocalization between T1 and the carbazoles.