A new family of Ru(II) polypyridyl complexes containing open-chain crown ether for Mg2+ and Ca2+ probing.
Six polypyridyl bridging ligands BL(1-6) containing open-chain crown ether, where BL(1-3) formed by the condensation of 4,5-diazafluoren-9-hydrazine with 1,7-bis-(4-formylphenyl)-1,4,7-trioxaheptane, 1,10-bis-(4-formylphenyl)-1,4,7,10-tetraoxadecane, and 1,13-bis-(4-formylphenyl)-1,4,7,10,13-pentaoxatridecane, respectively, BL(4-6) formed by the reaction of 9-(4-hydroxy)phenylimino-4,5-diazafluorene with diethylene glycol di-p-tosylate, triethylene glycol di-p-tosylate, and tetraethylene glycol di-p-tosylate, respectively, have been synthesized. Reaction of Ru(bpy)(2)Cl(2).2H(2)O with BL(1-6), respectively, afforded six bimetallic complexes [(bpy)(2)RuBL(1-6)Ru(bpy)(2)](4+) as PF(6)(-) salts. Cyclic voltammetry of these complexes is consistent with one Ru(II)-centered oxidation around 1.32V and three ligand-centered reductions. These complexes show metal-to-ligand charge transfer absorption at 413-444 nm and emission at 570 nm. Binding behavior of complexes with alkali and alkaline-earth metal ions are investigated by UV-vis absorption, fluorescence, and cyclic voltammetry. Addition of alkali and alkaline-earth metal ions to the solution of [(bpy)(2)RuBL(1-6)Ru(bpy)(2)](PF(6))(4) all result in a progressive quenching of fluorescence, a hyperchromic effect of UV-vis absorption, and a progressive cathodal shift of Ru(II)-centered E(1/2). Ru-BL(2) and Ru-BL(5) show the highest binding ability toward Mg(2+) among the five cations examined while Ru-BL(3) and Ru-BL(6) exhibit good selective recognition ability to Ca(2+).
Cheng
Feixiang
F
College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
Tang
Ning
N
Yue
Xing
X
D000042:Absorption; D002118:Calcium / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D043844:Crown Ethers / Q000737:chemistry*; D004563:Electrochemistry; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry*; D008954:Models, Biological; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010777:Photochemistry; D012428:Ruthenium / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D002412:Cations; D043844:Crown Ethers; D046911:Macromolecular Substances; D009942:Organometallic Compounds; D012428:Ruthenium; D008274:Magnesium; D002118:Calcium