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

摘要

A new anionic ruthenium(II)complex,(Et_4N)[Ru(tpyA18C6)(CN)_3](tpyA18C6 = N-[4'-(2,2':6',2"-terpyrid-yl)]-1,4,7,10,13-pentaoxa-16-azacyclo-hexadodecane),has been synthesized and characterized.The complex was found to show pronounced solvato-chromic behavior and,when dissolved in solution,changed its color from purple to yellow when the solvent system was varied from pure acetoni-trile 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 elec-trochemiluminescence(ECL)of the complex were also found to be progres-sively quenched as the proportion of water in a water/acetonitrile mixture increased.Large changes in the chemical shifts of the ~1H NMR and ~(13)C 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 chromatogra-phy for separation of metal cations and amino acids.Comparison studies with the crown-free analogue,(Et_4N)[Ru-(tpy)(CN)_3](tpy = 2,2':6',2"-terpyri-dine),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 nonabsorb-ing 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.