Search

Charge transfer complexes (CTCs) have become a promising and new class of photothermal conversion materials, in which the donor and acceptor can be regulated to control the energy gap, facilitating efficient absorption of near-infrared light. However, the successful co-crystallization of appropriate donor and acceptor pairs to form CTCs remains a challenging endeavor, as it requires addressing crucial issues including structural matching, co-assembly and crystallization conditions. Herein, on the basis of retaining the 'autonomy' of the assembly process, we leverage charge transfer and electron transfer processes of pyridinium building blocks to manipulate the photothermal behaviour in two distinct CTCs. Notably, CTC-1OH exhibits electron transfer initiated near-infrared photothermal conversion, while CTC-2OH has an intrinsic charge transfer-dependent photothermal effect with a photothermal efficiency as high as 35.4%. This work opens a new avenue for the development and optimization of the photothermal effect of CTCs. [ABSTRACT FROM AUTHOR]

Cleaving the C–C bonds in lignin to afford value-added low-molecular-weight aromatic products is promising but a challenging project. In this contribution, a mild and efficient strategy for one-step selective C–C bond cleavage in β-O-4 and β-1 lignin models has been developed over pyridinium-based photocatalysts. The strong electron-accepting ability of the pyridinium core unit and the neutral nitrogen atom of the pyridazine substituent group provide a proton coupled electron transfer (PCET) channel to promote hydrogen dissociation from the OH or CH groups to form the corresponding free radical intermediates, thus directly triggering the cleavage of C–C bonds via a β-scission process. Benzaldehyde and phenyl formate are eventually formed as the main products. This work not only enriches the application of the pyridinium family as a low-cost, eco-friendly, and sustainable alternative for producing value-added chemicals from renewable biomass resources, but also provides a new idea for designing novel organic catalysts with PCET features to decrease the consumption of precious metals. [ABSTRACT FROM AUTHOR]

Modulating charge transfer (CT) interactions between donor and acceptor molecules may give rise to unique dynamic changes in physicochemical properties, exhibiting great importance in supramolecular chemistry and materials science. In this work, we demonstrate the first instance of reversible photomodulation of donor‐acceptor (D−A) CT interaction in the solid state. Pyridinium‐based chromophore featuring π‐conjugated D−A structures can not only function as a good electron acceptor to undergo photoinduced electron transfer (ET) or engage in intermolecular CT interaction, but also exhibit unique dual emission depending on the excitation wavelengths. The rotatable C−C single bonds within D−A pairs enhance the tunability of molecular structure. Through the synergy of a photoinduced ET and an excited‐state conformational change, the intermolecular CT interaction can be switched on and off by alternate light irradiation to enable reversibly modulation of the affinity between donor and acceptor molecules, accompanied by visual color switching and fluorescence on‐off as feedback signals. [ABSTRACT FROM AUTHOR]