南京大学的左景林团队开发了一系列的四硫富瓦烯基2D金属有机骨架并阐述了其在高效光热能转换中的应用。 该研究成果发表于2020年11月25日出版的《德国应用化学》。

持久性自由基金属有机骨架（MOFs）的合成是其功能的扩展的一项重大挑战。

该文中，研究人员利用原位溶剂热法组装了一系列间-四硫富瓦烯-四苯甲酸（m-TTFTB）连接的2D-MOF。三聚体间-四硫富瓦烯-四苯甲酸稳定的节点有利于未配对电子离域自由基的稳定性。同时，六核稀土团簇结构一维链的存在也进一步提高了金属有机框架的稳定性。用X射线单晶衍射技术分析了三聚态m-TTFTB中间配体的C-C、C-S键变化以及其构型，并观测了其自由基态。电子顺磁共振、紫外-可见-近红外吸收和X射线光电子能谱实验也证实了其自由基特性。

稳定性测试表明，即使在非水/水溶液和酸碱环境（pH 1‐12）下，MOF中的这些自由基也是稳定的。由于分子内电荷转移的高效光吸收能力、低的热导率和优异的稳定性， 2D的Dy-MOF表现出优异的光热性能，在单日照射下 240秒内可升高34.7 ℃。

研究结果证实了电子离域作用下持久自由基MOFs的稳定性及其在光热转化中的应用，拓展了其在太阳能利用、光热治疗、海水淡化、光热催化等方面的应用前景。

附：英文原文

Title: Persistent Radical Tetrathiafulvalene‐based 2D Metal‐Organic Frameworks and their Application in Efficient Photothermal Conversion

Author: Jian Su, Ning Xu, Ryuichi Murase, Zhi-Mei Yang, Deanna M DAlessandro, Jing-Lin Zuo, Jia Zhu

Issue&Volume: 25 November 2020

Abstract: The synthesis of persistent radical metalorganic frameworks (MOFs) represents a significant challenge that underpins the expansion of their functionalities. Herein, via an  in situ  solvothermal method, a series of stable radical 2D MOFs have been assembled. The existence of (  m  ‐TTFTB)  3  (  m  ‐tetrathiafulvalene‐tetrabenzoate) trimer building blocks is beneficial for the stability of radicals due to delocalization of the unpaired electron. The presence of hexanuclear rare earth (RE) cluster‐based infinite one‐dimensional chains further enhances the stability of the frameworks. The radical state of the middle TTF in the trimer has been observed by the change of central CC and CS bond distances and the configuration of the TTF by single crystal X‐ray diffraction. The radical characteristics are also confirmed by electron paramagnetic resonance, UV‐Vis‐NIR absorption, and X‐ray photoelectron spectroscopy experiments. Stability tests showed that these radials in the frameworks are stable even in non‐aqueous/aqueous solutions and under acid/base environments (pH 1‐12). Owing to the efficient light‐absorption ability from intramolecular charge transfer, low thermal conductivity and outstanding stability, the radical 2D Dy‐MOF shows excellent photothermal properties, an increase of 34.7 °C within 240 seconds under one‐sun illumination. The results demonstrate the stability of persistent radical MOFs by electron delocalization and their application in photothermal conversion, expanding their future applications in solar energy utilization, photothermal therapy, seawater desalination, photothermal catalysis and so on.

DOI: 10.1002/anie.202013811

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202013811