Use of a fluorinated probe to quantitatively monitor amino acid binding preferences of ruthenium() arene complexes

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 2; pp. 691 - 692
• Main Authors: Biggs, George S, O'Neill, Michael J, Carames Mendez, Pablo, Scrase, Thomas G, Lin, Yulu, Bin-Maarof, Amzar Muzani, Bond, Andrew D, Boss, Sally R, Barker, Paul D
• Format: Journal Article
• Language: English
• Published: England 21.05.2019
• ISSN: 1477-9226; 1477-9234; 1477-9234
• DOI: 10.1039/c8dt05159c

In order to address outstanding questions about ruthenium complexes in complex biological solutions, 19 F NMR spectroscopy was used to follow the binding preferences between fluorinated Ru II (η 6 -arene)(bipyridine) complexes and protected amino acids and glutathione. Reporting what ruthenium compounds bind to in complex environments has so far been restricted to relatively qualitative methods, such as mass spectrometry and X-ray spectroscopic methods; however, quantitative information on the species present in the solution phase cannot be inferred from these techniques. Furthermore, using 1 H NMR, in water, to distinguish and monitor a number of different complex Ru II (η 6 -arene) adducts forming is challenging. Incorporating an NMR active heteroatom into ruthenium organometallic complexes provides a quantitative, diagnostic 'fingerprint' to track solution-phase behaviour and allow for unambiguous assignment of any given adduct. The resulting 19 F NMR spectra show for the first time the varied, dynamic behaviour of organoruthenium compounds when exposed to simple biomolecules in complex mixtures. The rates of formation of the different observed species are dramatically influenced by the electronic properties at the metal, even in a closely related series of complexes in which only the electron-donating properties of the arene ligand are altered. Preference for cysteine binding is absolute: the first quantitative solution-phase evidence of such behaviour. Speciation of Ru( ii ) arene complexes in mixtures of amino acids with coordinating sidechains is easily resolved by 19 F NMR.