Electrochemiluminescent Peptide Nucleic Acid-Like Monomers Containing Ru(II)鈥揇ipyridoquinoxaline and Ru(II)鈥揇ipyridophenazine Complexes
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- 作者：Tanmaya Joshi ; Gregory J. Barbante ; Paul S. Francis ; Conor F. Hogan ; Alan M. Bond ; Leone Spiccia
- 刊名：Inorganic Chemistry
- 出版年：2011
- 出版时间：December 5, 2011
- 年：2011
- 卷：50
- 期：23
- 页码：12172-12183
- 全文大小：556K
- 年卷期：v.50,no.23(December 5, 2011)
- ISSN：1520-510X
文摘
A series of Ru(II)鈥損eptide nucleic acid (PNA)-like monomers, [Ru(bpy)2(dpq-L-PNA鈥揙H)]2+ (M1), [Ru(phen)2(dpq-L-PNA鈥揙H)]2+ (M2), [Ru(bpy)2(dppz-L-PNA鈥揙H)]2+ (M3), and [Ru(phen)2(dppz-L-PNA鈥揙H)]2+ (M4) (bpy = 2,2鈥?bipyridine, phen = 1,10-phenanthroline, dpq-L-PNA鈥揙H = 2-(N-(2-(((9H-fluoren-9-yl)methoxy)carbonylamino)ethyl)-6-(dipyrido[3,2-a:2鈥?3鈥?c]phenazine-11-carboxamido)hexanamido)acetic acid, dppz-L-PNA鈥揙H = 2-(N-(2-(((9H-fluoren-9-yl) methoxy)carbonylamino)ethyl)-6-(dipyrido[3,2-f:2鈥?3鈥?h]quinoxaline-2-carboxamido)acetic acid) have been synthesized and characterized by IR and 1H NMR spectroscopy, mass spectrometry, and elemental analysis. As is typical for Ru(II)鈥搕ris(diimine) complexes, acetonitrile solutions of these complexes (M1鈥?b>M4) show MLCT transitions in the 443鈥?55 nm region and emission maxima at 618, 613, 658, and 660 nm, respectively, upon photoexcitation at 450 nm. Changes in the ligand environment around the Ru(II) center are reflected in the luminescence and electrochemical response obtained from these monomers. The emission intensity and quantum yield for M1 and M2 were found to be higher than for M3 and M4. Electrochemical studies in acetonitrile show the Ru(II)鈥揚NA monomers to undergo a one-electron redox process associated with RuII to RuIII oxidation. A positive shift was observed in the reversible redox potentials for M1鈥?b>M4 (962, 951, 936, and 938 mV, respectively, vs Fc0/+ (Fc = ferrocene)) in comparison with [Ru(bpy)3]2+ (888 mV vs Fc0/+). The ability of the Ru(II)鈥揚NA monomers to generate electrochemiluminescence (ECL) was assessed in acetonitrile solutions containing tripropylamine (TPA) as a coreactant. Intense ECL signals were observed with emission maxima for M1鈥?b>M4 at 622, 616, 673, and 675 nm, respectively. At an applied potential sufficiently positive to oxidize the ruthenium center, the integrated intensity for ECL from the PNA monomers was found to vary in the order M1 (62%) > M3 (60%) > M4 (46%) > M2 (44%) with respect to [Ru(bpy)3]2+ (100%). These findings indicate that such Ru(II)鈥揚NA bioconjugates could be investigated as multimodal labels for biosensing applications.