广东工业大学何军研究团队报道了从硫功能化的富炔晶体框架制备解稳定、浓缩的自由基，及其在太阳能-蒸汽转化中的应用研究。相关研究成发表在2024年6月27日出版的《结构化学》。

有机自由基具有多功能的不成对电子，是光电子和生物医学应用的关键，但仍难以以稳定的浓缩形式获得。

研究人员公开了从各种炔基苯基基序容易产生稳定、浓缩的自由基，包括1）结晶框架中的硫官能化的富含炔烃的有机连接体；2） 单独的这些分子的粉末；3） 简单的二乙基苯。对于Zr基框架，通过在300~450°C范围内的热退火实现了富自由基结晶框架的产生。对于末端炔烃，电子顺磁共振信号（EPR；表示自由基）在空气暴露或温和加热（例如，70°C）后出现。

进一步加热（例如，150°C持续3小时）可将自由基浓度提高至3.30 mol kg^-1。对于更稳定的内部炔烃，也可以触发转化为多孔自由基固体，尽管温度更高（例如250至500°C）。所得含自由基的固体是多孔的，对空气和热量（高达300~450°C）稳定，并表现出光热转换和太阳能驱动的水蒸发能力。自由基的形成可归因于广泛的炔烃环化、形成缺陷、悬挂键和由多环π-体系稳定的相关自由基。

附：英文原文

Title: Insight into stable, concentrated radicals from sulfur-functionalized alkyne-rich crystalline frameworks and application in solar-to-vapor conversion

Author: Jian-Rong Li, Jieying Hu , Lai-Hon Chung, Jilong Zhou, Parijat Borah, Zhiqing Lin, Yuan-Hui Zhong, Hua-Qun Zhou, Xianghua Yang, Zhengtao Xu, Jun He

Issue&Volume: 2024-06-27

Abstract: Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications but remain difficult to access in stable concentrated forms. We disclose easy generation of stable, concentrated radicals from various alkynyl phenyl motifs, including 1) sulfur-functionalized alkyne-rich organic linkers in crystalline frameworks; 2) the powders of these molecules alone; 3) simple diethynylbenzenes. For Zr-based framework, generation of radical-rich crystalline framework was achieved by thermal annealing in the range of 300450 °C. For terminal alkynes, electron paramagnetic resonance signals (EPR; indicative of free radicals) arise after air exposure or mild heating (e.g., 70 °C). Further heating (e.g., 150 °C for 3 hours) raises the radical concentrations up to 3.30 mol kg1. For the more stable internal alkynes, transformations into porous radical solids can also be triggered, albeit at higher temperatures (e.g., 250 to 500 °C). The resulted radical-containing solids are porous, stable to air as well as heat (up to 300450 °C) and exhibit photothermal conversion and solar-driven water evaporation capacity. The formation of radicals can be ascribed to extensive alkyne cyclizations, forming defects, dangling bonds and the associated radicals stabilized by the polycyclic π-systems.

DOI: 10.1016/j.cjsc.2024.100380

Source: http://cjsc.ac.cn/cms/issues/656