Chen Zi-Yi, Xie Kai-Ping, Cheng Yue, Deng Yi-Fei, Zhang Yuan-Zhu
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, 518055, China.
School of Chemistry and Materials Engineering, Huizhou University, Huizhou, 516007, China.
Adv Sci (Weinh). 2024 Aug;11(30):e2402884. doi: 10.1002/advs.202402884. Epub 2024 Jun 14.
The construction of large and complex supramolecular architectures through self-assembly is at the forefront of contemporary coordination chemistry. Notwithstanding great success in various systems using anionic bridges (e.g., O or S) or organic ligands (e.g., pyridine or carboxylate ligands), the assembly of large cyanide-bridged clusters with increasing nuclearity remains a formidable synthetic challenge. In this study, it is achieved in preparing two heterometallic cyanometallate clusters with unprecedented complexity, [FeCo] (1) and [FeCo] (2), by creating the "flexibility" through a versatile ligand of bis((1H-imidazol-4-yl)methylene)hydrazine (HL) and low-coordinate cobalt. Complex 1 features a super-square array of four cyanide-bridged [FeCo] cube subunits as the corners that are interconnected by four additional [FeCo] units, resulting in a torus-shaped architecture. Complex 2 contains a lantern-like core-shell cluster with a triple-helix kernel of [CoL] enveloped by a [FeCo] shell. The combined structure analysis and mass spectrometry study reveal a hierarchical assembly mechanism, which sheds new light on constructing cyanometallate nanoclusters with atomic precision. Moreover, complex 1 undergoes a thermally induced electron-transfer-coupled spin transition (ETCST) between the diamagnetic {Fe (µ-CN)Co } and paramagnetic {Fe (µ-CN)Co } configurations (LS = low spin, HS = high spin) above room temperature, representing the largest molecule displaying electron transfer and spin transition characteristic.
通过自组装构建大型复杂的超分子结构处于当代配位化学的前沿。尽管在使用阴离子桥（如O或S）或有机配体（如吡啶或羧酸盐配体）的各种体系中取得了巨大成功，但组装具有增加核数的大型氰基桥联簇仍然是一项艰巨的合成挑战。在本研究中，通过双（（1H-咪唑-4-基）亚甲基）肼（HL）的多功能配体和低配位钴创造“灵活性”，成功制备了两个具有前所未有的复杂性的异金属氰基金属酸盐簇，[FeCo]（1）和[FeCo]（2）。配合物1具有由四个氰基桥联的[FeCo]立方体亚基组成的超方形阵列作为角，这些角通过另外四个[FeCo]单元相互连接，形成环形结构。配合物2包含一个灯笼状的核壳簇，其具有由[FeCo]壳包围的[CoL]三螺旋核。结合结构分析和质谱研究揭示了一种分级组装机制，这为以原子精度构建氰基金属酸盐纳米簇提供了新的思路。此外，配合物1在室温以上经历了抗磁性的{Fe(µ-CN)Co}和顺磁性的{Fe(µ-CN)Co}构型（LS = 低自旋，HS = 高自旋）之间的热诱导电子转移耦合自旋转变（ETCST），这代表了显示电子转移和自旋转变特性的最大分子。
