ic0c01328_si_001.pdf (2.11 MB)
Zwitterionic Ru(III) Complexes: Stability of Metal–Ligand Bond and Host–Guest Binding with Cucurbit[7]uril
journal contribution
posted on 2020-07-07, 14:38 authored by Sanaz Malali, Jan Chyba, Michal Knor, Michal Horní, Marek Nečas, Jan Novotný, Radek MarekA 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.
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DABCOsingle-crystal X-ray diffractionzwitterionicsupramolecular anchorsNMR shiftsR-bipyridine ligands formhostruthenium-based coordination compoundspoint-dipole approximationDABCO-RRuCl 4through-bond Fermi-contact mechanismbindingcoordination stabilityNMR spectroscopyDFT calculationsantimetastatic activityParamagnetic 1 H NMR experiments
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