摘要
Switching on/off single-molecule magnets(SMMs)at room temperature is still a challenge in moleculebased magnets.Herein,two photochromic Ln-based(Ln=Dy,Tb)phosphonate coordinated polymers were synthesized with regulable SMM behavior.The reversible room-temperature photo-coloration was an electron transfer process with a generation of relatively stable radicals,characterized by structural analyses,ultraviolet-visible,luminescence and electron spin resonance spectra and magnetic measurements.Importantly,owing to the antiferromagnetic coupling interactions between Ln^(3+) ions and photogenerated radicals,the room-temperature light irradiation surprisingly switched off the SMM behavior,showing the first example of radicalquenched SMMs in the molecule-based magnets.Moreover,the silient SMM behavior could be recovered after eliminating photogenerated radicals via heat treatment,showing a reversible off/on switch of SMMs via light and heat.This work constructs a system for switching off/on SMMs through electron transfer photochromism,providing a visual operation way via naked-eye-detectable coloration for the switchable SMMs.
室温下实现单分子磁体(SMM)的开关行为仍然是分子磁体研究中的一个挑战.本文合成了两例具有SMM行为的光致变色Ln基(Ln=Dy,Tb)膦酸盐配合物.结构分析、紫外-可见光谱、发光光谱、电子自旋共振光谱和磁性测量等手段共同表明,目标产物的室温可逆光致变色行为是光生自由基诱导的电子转移过程.重要的是,由于Ln^(3+)与光生自由基间的反铁磁耦合作用,首次观测到室温光照可猝灭SMM行为.此外,通过热处理消除光生自由基后,SMM的行为得以恢复,因而通过光照和加热实现了可逆的SMM关/开变化.本工作在电子转移光致变色体系中实现SMM的可控开/关,为可调控的SMM提供了一种可视化的操作方式.
基金
supported by the National Natural Science Foundation of China(21901133,22171155 and 22071126)
the State Key Laboratory of Fine Chemicals(KF1905)。
