Purdy Michael, Wang Ariel Y, Drummer Matthew C, Nocera Daniel G, Liu Richard Y
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
Nat Chem. 2025 Aug 13. doi: 10.1038/s41557-025-01901-0.
Leading strategies for the capture of CO from point sources and directly from the atmosphere face high energy costs for thermal sorbent regeneration. Photochemical processes, driven by sunlight as the sole external stimulus, offer a promising alternative. Despite many reported examples of light-induced pH swings using metastable photoacids, the complementary mode of operation, using photoswitchable bases, has not been extensively considered. This is due in part to the rarity of photobases that can support large, reversible pH jumps in water. Here we report the design of fluorenol-based Arrhenius photobases that take advantage of excited-state aromaticity and ground-state antiaromaticity to generate large basicity swings with high reversibility. The system is oxygen stable, can be driven by natural sunlight and captures/concentrates CO from ambient air. We elucidated the mechanism of C-O dissociation using transient absorption spectroscopy to understand the high efficiency of hydroxide release. This study provides a framework for the design of photoreversible aqueous bases and guiding principles for their use in solar-powered CO management.
从点源和直接从大气中捕获二氧化碳的主要策略面临着热吸附剂再生的高能量成本。由阳光作为唯一外部刺激驱动的光化学过程提供了一种有前景的替代方案。尽管有许多使用亚稳态光酸的光诱导pH值变化的报道实例，但使用光开关碱的互补操作模式尚未得到广泛考虑。这部分是由于能够在水中支持大的、可逆pH值跃变的光碱很少见。在此，我们报道了基于芴醇的阿累尼乌斯光碱的设计，该光碱利用激发态芳香性和基态反芳香性来产生具有高可逆性的大碱性变化。该系统对氧气稳定，可由自然阳光驱动，并能从环境空气中捕获/浓缩二氧化碳。我们使用瞬态吸收光谱法阐明了C-O解离的机制，以了解氢氧化物释放的高效率。这项研究为光可逆水性碱的设计提供了一个框架，并为其在太阳能驱动的二氧化碳管理中的应用提供了指导原则。
