Energy-Transfer-Mediated Photocatalysis by a Bioinspired Organic Perylenephotosensitizer HiBRCP

Heterogenization of Homogeneous Donor-Acceptor Conjugated Polymers for Efficient Photooxidation: An Approach Toward Sustainable and Recyclable Photocatalysis

Recovery of homogeneous photocatalysts from reaction mixture is challenging, affecting the cost-effectiveness, and masks their advantages, including 4-8 fold higher catalytic activity than corresponding heterogeneous counterparts. Incorporation of long alkyl chains within the rigid π-conjugated backbone of conjugated polymers can augment their solubility in particular organic solvents; accordingly, they can function as homogeneous photocatalysts. Consequently, these polymers facilitate the recovery of catalysts through the reverse dissolution process, thus creating a well-suited platform to meet certain advantages of both homo- and heterogeneous photocatalysts. This work exemplifies the unprecedented perks of donor-acceptor conjugated polymers from benzodithiophene and substituted dibenzothiophene sulfone moieties for their homogeneous phase photoredox activities along with their heterogeneous recovery and reuse up to five runs. The potential intermediate singlet oxygen (1O2) and superoxide (O2•-) as reactive oxygen species generated by these photostable conjugated polymers efficiently catalyze the visible-light-driven oxidation of aryl sulfides (up to 92% yield) and oxidative hydroxylation of phenylboronic acids (up to 93% yield), respectively. Therefore, to actualize the heightened catalytic performance and formulate a design strategy for polymeric photoredox catalyst, our work introduces an alternative approach to the advancement of photocatalysis with diverse catalytic activities.

Synthesis Enabled by E-to-Z Isomerization Using CBZ6 as Energy Transfer Photocatalyst

The reactions of Z-isomers and E-isomers usually are different in consideration of the regioselectivity of chemoselectivity. The syntheses of Z-isomers are not feasible in many cases. The energy transfer (EnT) E/Z-photoisomerization might yield the Z-isomers. In this work, CBZ6 was proven to be an EnT photocatalyst for the E → Z-isomerization of C-C or C-N double bonds. The transformations of in situ generated Z-isomers of oximes and stilbenes consequently afforded the desired reversed Beckmann rearrangement products and phenanthrenes, respectively.

Rejuvenation of dearomative cycloaddition reactions via visible light energy transfer catalysis

Dearomative cycloaddition is a powerful technique to access sp3-rich three-dimensional structural motifs from simple flat, aromatic feedstock. The building-up of unprecedentedly diverse polycyclic scaffolds with increased saturation and stereochemical information having various applications ranging from pharmaceutical to material sciences, is an essential goal in organic chemistry. However, the requirement of large energy inputs to disrupt the aromaticity of an arene moiety necessitates harsh reaction conditions for ground state dearomative cycloaddition. The photochemical requirement encompasses use of ultraviolet (UV) light to enable the reaction on an excited potential energy surface. The microscopic reversibility under thermal conditions and the use of high energy harmful UV irradiation in photochemical manoeuvres, however, constrain their widespread use from a synthetic point of view. In this context, the recent renaissance of visible light energy transfer (EnT) catalysis has become a powerful tool to initiate dearomative cycloaddition as a greener and more sustainable approach. The excited triplet state population is achieved by triplet energy transfer from the appropriate photosensitizer to the substrate. While employing mild visible light energy as fuel, the process leverages an enormous potential of excited state reactivity. The discovery of an impressive portfolio of organic and inorganic photosensitizers with a range of triplet energies facilitates visible light photosensitized dearomative cycloaddition of various substrates to form sp3-rich fused polycyclic architectures with diverse applications. The tutorial review comprehensively surveys the reawakening of dearomative cycloadditions via visible light-mediated energy transfer catalysis in the past five years. The progress ranges from intra- and intermolecular [2π + 2π] to [4π + 2π], and ends at intermolecular [2π + 2σ] cycloadditions. Furthermore, the review provides potential possibilities for future growth in the growing field of visible light energy transfer catalysis.

Gold-Catalyzed C-O Cross-Coupling Reactions of Aryl Iodides with Silver Carboxylates

We have developed a C-O cross-coupling reaction of (hetero)aryl iodides with silver carboxylates via a AuI/AuIII catalytic cycle. The transformation featured exclusive chemoselectivity and moisture/air insensitivity. Aromatic and aliphatic (including primary, secondary, and tertiary) silver carboxylates are all suitable substrates. Moreover, this protocol worked well intermolecularly and intramolecularly. Most importantly, good yields were obtained regardless of the substrates' electronic effect and steric hindrance.

Polymeric ionic liquid-based formulations for the fabrication of highly stable perovskite nanocrystal composites for photocatalytic applications

Halide perovskite nanocrystals (PNCs) have emerged as potential visible-light photocatalysts because of their outstanding intrinsic properties, including high absorption coefficient and tolerance to defects, which reduces non-radiative recombination, and high oxidizing/reducing power coming from their tuneable band structure. Nevertheless, their sensitivity to humidity, light, heat and water represents a great challenge that limits their applications in solar driven photocatalytic applications. Herein, we demonstrate the synergistic potential of embedding PNCs into polymeric ionic liquids (PILs@PS) to fabricate suitable composites for photodegradation of organic dyes. In this context, the stability of the PNCs after polymeric encapsulation was enhanced, showing better light, moisture, water and thermal stability compared to pristine PNCs for around 200 days.