Ruthenium organometallics of chloro-substituted 2′-hydroxychalcones – A story of catecholase biomimetics beyond copper

•Four Ru(II) organometallics of chloro substituted 2’-hydroxychalcones were prepared.•Solid state and solution structures were determined.•At low μM concentrations compounds have solvent-dependent catecholase activity.•The kinetic portrait of catechol oxidation in methanol and ethanol is not the same.•The highest catalytic activity was found in ethanol for complex with chloro substituent in para position at chalcone ligand.