Ruthenium terpyridine complexes containing a pyrrole-tagged 2,2'-dipyridylamine ligand-synthesis, crystal structure, and electrochemistry.
Ruthenium(II) terpyridine complexes containing the pyrrole-tagged 2,2'-dipyridylamine ligand PPP (where PPP stands for N-(3-bis(2-pyridyl)aminopropyl)pyrrole with the general formula [Ru(tpy)(PPP)X](n+) (1, X = Cl(-); 2, X = H(2)O; 3, X = CH(3)CN; tpy = 2,2':6',2"-terpyridine) have been synthesized and characterized by (1)H NMR, IR, UV-vis, mass spectrometry, and elemental analysis. 1 and 2 have been structurally characterized by X-ray crystallography. Both 1 and 2 were successfully immobilized onto glassy carbon electrode via anodic oxidation of the pyrrole moiety on the PPP ligand to give stable and highly electroactive polymer films. Cyclic voltammetric studies of 1 in acetonitrile revealed a Ru(III)/Ru(II) couple at 0.4 V vs Cp(2)Fe(+/0) initially, but another redox couple resulting from chloride substitution by acetonitrile developed at E(1/2) = 0.82 V upon repetitive potential scan. This ligand substitution was induced by the acidic local environment caused by the release of protons during pyrrole polymerization. The electropolymerization of 2 in aqueous medium allowed the observation of the formation of Ru(IV)═O species in polypyrrole film. As the film grew thicker, the size of the Ru(III)/(/)Ru(II) couple (E(1/2) = 0.8 V vs SCE at pH 1) of poly[Ru(tpy)(PPP)(OH(2))](n+) increased accordingly, whereas the growth of the Ru(IV)/Ru(III) couple (E(1/2) = 0.89 V vs SCE at pH 1) leveled off after the film had reached a certain thickness. The Pourbaix diagram of the E(1/2) of the Ru(III) /Ru(II) and Ru(IV)/Ru(III) couples vs pH of the electrolyte medium has been obtained. The resulting poly[Ru(tpy)(PPP)(OH(2))](n+) film is electrocatalytically active toward the oxidation of benzyl alcohol.
Department of Applied Biology and Chemical Technology and the State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong, China.
Kwong-Chak
KC
Cheung
Peng
P
Guo
Ming-Him
MH
So
Zhong-Yuan
ZY
Zhou
Lawrence Yoon Suk
LY
Lee
Kwok-Yin
KY
Wong
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
D008024:Ligands; D009942:Organometallic Compounds; D011725:Pyridines; D011758:Pyrroles; D015082:2,2'-Dipyridyl; D012428:Ruthenium; C048062:2,2'-dipyridylamine