A wide range of ruthenium-based coordination compounds have been reported to possess potential as metallodrugs with anticancer or antimetastatic activity. In this work, we synthesized a set of new zwitterionic Ru(III) compounds bearing ligands derived from N-alkyl (R) systems based on pyridine, 4,4′-bipyridine, or 1,4-diazabicyclo[2.2.2]octane (DABCO). The effects of the ligand(s) and their environment on the coordination stability have been investigated. Whereas the [DABCO-R]⁺ ligand is shown to be easily split out of a negative [RuCl₄]⁻ core, positively charged R-pyridine and R-bipyridine ligands form somewhat more stable Ru(III) complexes and can be used as supramolecular anchors for binding with macrocycles. Therefore, supramolecular host–guest assemblies between the stable zwitterionic Ru(III) guests and the cucurbit[7]uril host were investigated and characterized in detail by using NMR spectroscopy and single-crystal X-ray diffraction. Paramagnetic ¹H NMR experiments supplemented by relativistic DFT calculations of the structure and hyperfine NMR shifts were performed to determine the host–guest binding modes in solution. In contrast to the intramolecular hyperfine shifts, dominated by the through-bond Fermi-contact mechanism, supramolecular hyperfine shifts were shown to depend on the “through-space” spin–dipole contributions with structural trends being satisfactorily reproduced by a simple point-dipole approximation.

中文翻译：

---

两性离子Ru（III）配合物：金属-配体键的稳定性以及与葫芦[7] uril结合的来宾-客体。

据报道，各种各样的钌基配位化合物具有作为具有抗癌或抗转移活性的金属药物的潜力。在这项工作中，我们基于吡啶，4,4'-联吡啶或1,4-二氮杂双环[2.2.2]辛烷合成了一组新的两性离子Ru（III）化合物，这些化合物带有衍生自N-烷基（R）系统的配体（DABCO）。研究了配体及其环境对配位稳定性的影响。而[DABCO-R] ⁺配体显示很容易从负[RuCl ₄ ] ^-中分离出来^-核，带正电荷的R-吡啶和R-联吡啶配体形成更稳定的Ru（III）配合物，可用作与大环结合的超分子锚。因此，研究了稳定的两性离子Ru（III）客体与葫芦[7] uril主体之间的超分子主体-客体组装，并使用NMR光谱学和单晶X射线衍射对其进行了详细表征。顺磁性¹进行了H NMR实验，并通过相对论DFT计算结构和超精细NMR位移来确定溶液中的主客体结合模式。与通过键费米接触机制控制的分子内超精细位移相反，超分子超精细位移被证明取决于“贯穿空间”自旋偶极子的贡献，其结构趋势通过简单的点-偶极近似可令人满意地再现。 。