Supramolecular Ensemble of a TICT-AIEE Active Pyrazine Derivative and CuO NPs: A Potential Photocatalytic System for Sonogashira Couplings

Abstract

The donor–acceptor system 4 having pyrazine scaffold as an acceptor moiety coupled to donor amino groups through rotatable phenyl rings has been synthesized, which formed aggregates in aqueous media, exhibited copper induced restriction to intramolecular rotation, and served as a “not quenched” probe for the detection of copper­(II) ions. During this process, the aggregates of derivative 4 acted as reactors and stabilizers for the generation of CuO NPs and themselves became oxidized to form polyamine derivative 6. Interestingly, the oxidized species 6 in combination with copper oxide nanoparticles served as light-harvesting antennas and exhibited excellent photocatalytic efficiency in Sonogashira coupling under mild and eco-friendly conditions (room temperature, aqueous media, aerial conditions, and visible light irradiation).

Cu2O Nanocrystals‐Catalyzed Photoredox Sonogashira Coupling of Terminal Alkynes and Arylhalides Enhanced by CO2

“…Heterogeneous catalysts are important owing to their recyclability and easy separation/recovery, especially in industrial applications. Recently, a few reports demonstrated the feasibility of photoinduced heterogeneous catalysis for Sonogashira cross‐coupling at room temperature, such as: a) using a supramolecular ensemble of a twisted intramolecular charge‐transfer states aggregation‐induced emission enhancement (TICT‐AIEE) active pyrazine and CuO nanoparticles (Scheme b); b) a silicon carbide‐supported Pd–Cu alloy (Pd 3 Cu 1 /SiC) or TiO 2 supported palladium NPs (Pd@TiO 2 ) (Scheme c); and c) TiO 2 ‐supported CuO bimetallic photocatalysts (Scheme d), for which cocatalysis of Ti to Cu ions is required for the coupling reactions to occur . Despite increased attention, most heterogeneous NP‐based catalysts still have some limitations.…”

Entropically Favoured Assembly of Pyrazine‐Based Helical Fibers into Superstructures: Achiral/ Chiral Guest‐Induced Chirality Transformation

“…Thus,wedesigned and synthesized pyrazine derivative 1 which has l-alanine moieties as the chiral handle and amide linkages as binding units.Wechose pyrazine as ascaffold because of its known potential to form fluorescent aggregates through p-p intermolecular stacking and the hydrophobic effect in an aggregated state in aqueous media. [19] Derivative 1 undergoes self-assembly to generate fluorescent helical fibers in aqueous media and the alanine groups can transfer chirality in the aggregated state.T he as-prepared helical fibers exhibit as elective affinity towards Ni 2+ ions,a nd the co-assembly of helical fibers and Ni 2+ ions results in ac hirality transformation. Fortunately,c hirality inversion was accompanied by further aggregation of the helical fibers to generate as upercoiled 1:Ni 2+ ensemble.…”

Heterogeneous Photocatalyzed C−C Cross‐coupling Reactions Under Visible‐light and Near‐infrared Light Irradiation

“…However, poor recyclability of this noble‐metal free photocatalyst for the Suzuki coupling reaction was found that the yield was decreased by 30 % after 4 recycles. Also, they prepared other noble‐metal free photocatalyst for visible light photocatalyzed Sonogashira C−C cross coupling . The photocatalyst was composed of TICT‐AIEE active pyrazine derivative and CuO nanoparticles, which exhibited excellent catalytic efficiency in Sonogashira couplings under mild conditions with a wide variety of substrates.…”