Search

The multifunctional derivatization of alcohols has been achieved by the bipyridinium‐based conjugated small molecule photocatalysts with redox center and Lewis acid site. Besides exhibiting high activity in the selective generation of aldehydes/ketones, acids from alcohols through solvent modulation, this system renders the first selective synthesis of esters via an attractive cross‐coupling pattern, whose reaction route is significantly different from the traditional condensation of alcohols and acids or esterification from hemiacetals. Following the oxidization of alcohol to aldehyde via bipyridinium‐mediated electron and energy transfer, the Lewis acid site of bipyridinium then activates the aldehyde and methanol to obtain the acetal, which further reacts with methanol to generate ester. This method not only demonstrates a clear advantage of bipyridinium in diverse catalytic activities, but also paves the way for designing efficient multifunctional small molecule photocatalysts. This metal‐ and additive‐free photocatalytic esterification reaction marks a significant advancement towards a more environmentally friendly, cost‐effective and green sustainable approach, attributed to the utilization of renewable substrate alcohol and the abundant, low‐cost air as the oxidant. The mildness of this esterification reaction condition provides a more suitable alternative for large‐scale industrial production of esters. [ABSTRACT FROM AUTHOR]

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]

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 enables reversibly modulation of the affinity between donor and acceptor molecules, accompanied by visual color switching and fluorescence on-off as feedback signals., (© 2024 Wiley‐VCH GmbH.)