Synthesis, Characterization, Spectroscopic, and Electrochemiluminescence Properties of a Solvatochromic Azacrown‐Containing Cyanoruthenate(II): Potential Applications in Separation and Indirect Photometric Detection of Cations and Amino Acids in HPLC

Abstract

A new anionic ruthenium(II) complex, (Et4N)[Ru(tpyA18C6)(CN)3] (tpyA18C6=N-[4'-(2,2':6',2''-terpyridyl)]-1,4,7,10,13-pentaoxa-16-azacyclohexadodecane), has been synthesized and characterized. The complex was found to show pronounced solvatochromic behavior and, when dissolved in solution, changed its color from purple to yellow when the solvent system was varied from pure acetonitrile to pure water. Its absorption and emission energies in various solvents showed a linear dependence of the Gutman's acceptor number. The characteristic photoluminescence and electrochemiluminescence (ECL) of the complex were also found to be progressively quenched as the proportion of water in a water/acetonitrile mixture increased. Large changes in the chemical shifts of the 1H NMR and 13C NMR signals of [Ru(tpyA18C6)(CN)3]- in different solvents were observed. The complex has also been demonstrated to serve as a mobile-phase additive in high-performance liquid chromatography for separation of metal cations and amino acids. Comparison studies with the crown-free analogue, (Et4N)[Ru(tpy)(CN)3] (tpy = 2,2':6',2''-terpyridine), showed that other than the ion-pair effect, the allosteric host-guest interaction provided by the presence of the pendant crown was essential to the separation performance of the complex. Indirect detection of nonabsorbing analytes has been achieved by monitoring the absorbance changes of the eluent at the metal-to-ligand charge-transfer (MLCT) absorption band maximum of the complex at 445 nm. The effects of pH, ionic strength, and polarity of the mobile phase as well as the complex concentration on the selectivity and resolution have also been studied.

Multifunctional Ruthenium(II) Polypyridine Complex-Based Core–Shell Magnetic Silica Nanocomposites: Magnetism, Luminescence, and Electrochemiluminescence

“…The diameters of most silica-coated magnetic NPs and dye-encapsulated silica NPs prepared and studied are larger than 50 nm, and there has been a growing interest in the synthesis of smaller-sized functional magnetic NPs as this would facilitate their applications in biomedical sciences because of their higher surface area and the possibility of larger dye loading. From our recent interest in the synthesis of functional nanoparticles – and our long-standing interest in luminescent metal-based materials, – here we report the synthesis and investigation of multifunctional core-shell magnetic silica nanocomposites, with the Fe 3 O 4 core coated with a silica shell, to which luminescent ruthenium(II) complexes were covalently attached and further encapsulated with an additional layer of silica shell. The magnetic, luminescent, and ECL behavior of these nanocomposites has also been studied.…”

Enantioselective transition metal catalysis directed by chiral cations

“…The Yam group prepared a novel ruthenium anion complex NEt 4 [Ru(tpyA18C6)(CN) 3 ] and used it as a mobile-phase additive to separate metal-ions in high-performance liquid chromatography ( Scheme 12, B ). 19 The solvatochromic behavior and photoluminescence of [Ru(tpyA18C6)(CN) 3 ] − indicate its UV absorption properties. The solvent dependence of metal-to-ligand charge transfer (MLCT) absorption bands shows that active wavelengths are in the visible region.…”

Chromo- and Fluorogenic Organometallic Sensors

“…1) which exhibits selective cation-binding behaviour (through the azacrown pendant) and pH-sensitivity (through protonation of the cyanide ligands). The complex has been shown to be a good candidate for sensing subtle humidity changes and to serve as a mobile-phase additive in high-performance liquid chromatography (HPLC) for the separation of alkali and alkaline-earth metal cations, as well as amino acids [15]. The cation-binding properties of a Ru(II)-carbene derivative with a benzo-15-crown-5 pendant have also been reported [16].…”