Zhang Shu-Ya, Sun Hui-Ying, Wang Run-Guo, Meng Yin-Shan, Liu Tao, Zhu Yuan-Yuan
School of Chemistry and Chemical Engineering, Hefei University of Technology and Anhui Key Laboratory of Advanced Functional Materials and Devices, Hefei 230009, China.
State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2 Linggong Road, Dalian 116024, China.
Dalton Trans. 2022 Jun 27;51(25):9888-9893. doi: 10.1039/d2dt00436d.
The self-assembly of multinuclear SCO complexes is appealing in which unique properties may be discovered due to enhanced intramolecular and intermolecular interactions. In this work, three dinuclear cobalt(II) complexes, named Co-1, Co-2, and Co-3, were prepared based on a complementary terpyridine ligand pair strategy. The complexes were accurately synthesized by the solvothermal method in which dinuclear complexes were directional assemblies from cobalt(II) ions, terpy bearing 2,6-dimethoxyphenyl substituents at the terpyridyl 6,6''-positions, and ditopic terpy built with different linkers (alkynyl for 1, diynyl for 2, and phenyl for 3). Single-crystal structure determinations reveal that all compounds possess a central symmetric molecular structure, so that two cobalt(II) units are identical in the solid state. Their spin crossover behaviours were investigated through variable-temperature magnetic susceptibility studies. Co-1 undergoes limited SCO with a large population of low spin state ( = 1/2) in the measured temperatures. Co-2 and Co-3 exhibit solvent-modulated SCO behaviour. Impressively, the de-solvated samples show a repeatable thermal hysteresis loop around the room temperature region. This work demonstrates that complementary terpyridine ligand pairing is a practical approach to accurate and directional construction of multinuclear SCO-active compounds.
多核自旋交叉（SCO）配合物的自组装很有吸引力，因为分子内和分子间相互作用增强可能会发现独特的性质。在这项工作中，基于互补的三联吡啶配体对策略制备了三种双核钴（II）配合物，命名为Co-1、Co-2和Co-3。通过溶剂热法精确合成了这些配合物，其中双核配合物是由钴（II）离子、在三联吡啶6,6''-位带有2,6-二甲氧基苯基取代基的三联吡啶以及用不同连接基构建的双功能三联吡啶（1为炔基，2为二炔基，3为苯基）定向组装而成。单晶结构测定表明，所有化合物都具有中心对称的分子结构，因此在固态下两个钴（II）单元是相同的。通过变温磁化率研究考察了它们的自旋交叉行为。Co-1在测量温度范围内经历有限的SCO，低自旋态（ = 1/2）的比例很大。Co-2和Co-3表现出溶剂调制的SCO行为。令人印象深刻的是，去溶剂化样品在室温区域附近显示出可重复的热滞回线。这项工作表明，互补的三联吡啶配体配对是精确和定向构建多核SCO活性化合物的一种实用方法。
