We report a novel, inexpensive and effective process for the repeatable photoisomerization of norbornadiene (NBD) to its metastable isomer quadricyclane (QC), followed by catalytically induced strain energy release via back‐conversion of QC to NBD. By utilization of a quasi‐homogeneous catalyst based on magnetic core‐shell nanoparticles, tedious purification steps are avoided. The core of this material is comprised of Fe₃O₄ and a catalytically active cobalt(II) complex is anchored on the particle surface as a self‐assembled monolayer (SAM). These core‐shell nanoparticles [Fe₃O₄−CoSalphen] combine a high surface area of catalytically active molecules with straightforward separation by the action of an external magnetic field. In combination with the promising interconversion couple NBD1‐QC1, which features outstanding stability (t_1/2=450 days at room temperature) and a high energy storage potential (88.34 kJ/mol), the nanoparticle catalyst [Fe₃O₄−CoSalphen] shows great potential for technical applications in molecular solar thermal (MOST) energy‐storage systems.

中文翻译：

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磁性[Fe3O4-CoSalphen]纳米粒子催化剂介导的降冰片二烯-四环烷互变的有效环化。

我们报道了一种新颖，廉价且有效的过程，用于降冰片二烯（NBD）可重复光异构化为其亚稳定的异构体四环烷（QC），然后通过QC反向转化为NBD进行催化诱导的应变能释放。通过利用基于磁性核壳纳米粒子的准均相催化剂，避免了繁琐的纯化步骤。这种材料的核心由Fe ₃ O _4组成，并且具有催化活性的钴（II）络合物以自组装单层（SAM）的形式固定在颗粒表面。这些核壳纳米颗粒[Fe ₃ O ₄-CoSalphen]通过外部磁场的作用将催化活性分子的高表面积与直接分离相结合。纳米粒子催化剂[Fe ₃ O ₄ -CoSalphen]与具有良好稳定性（室温下t _1/2 = 450天）和高储能潜力（88.34 kJ / mol）的有前景的互变对NBD1-QC1结合使用]在分子太阳能热（MOST）能量存储系统中显示出巨大的技术应用潜力。