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Synthesis and Spectroelectrochemistry of Ir(bpy)(phen)(phi)^(3+), a Tris(heteroleptic) Metallointercalator

Stinner, Christine and Wightman, Matthew D. and Kelley, Shana O. and Hill, Michael G. and Barton, Jacqueline K. (2001) Synthesis and Spectroelectrochemistry of Ir(bpy)(phen)(phi)^(3+), a Tris(heteroleptic) Metallointercalator. Inorganic Chemistry, 40 (20). pp. 5245-5250. ISSN 0020-1669. doi:10.1021/ic010376t.

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A tris(heteroleptic) phenanthrenequinone diimine (phi) complex of Ir(III), Ir(bpy)(phen)(phi)^(3+), was synthesized through the stepwise introduction of three different bidentate ligands, and the Λ- and Δ-enantiomers were resolved and characterized by CD spectroscopy. Like other phi complexes, this tris(heteroleptic) iridium complex binds avidly to DNA by intercalation. Electrochemical studies show that Ir(bpy)(phen)(phi)^(3+) undergoes a reversible one-electron reduction at E_0 = -0.025 V in 0.1 M TBAH/DMF (versus Ag/AgCl), and spectroelectrochemical studies indicate that this reduction is centered on the phi ligand. The EPR spectrum of electrochemically generated Ir(bpy)(phen)(phi)^(2+) is consistent with a phi-based radical. The electrochemistry of Ir(bpy)(phen)(phi)^(3+) was also probed at a DNA-modified electrode, where a DNA binding affinity of K = 1.1 x 10^6 M^(-1) was measured. In contrast to Ir(bpy)(phen)(phi)^(3+) free in solution, the complex bound to DNA undergoes a concerted two-electron reduction, to form a diradical species. On the basis of UV-visible and EPR spectroscopies, it is found that disproportionation of electrochemically generated Ir(bpy)(phen) (phi)^(2+) occurs upon DNA binding. These results underscore the rich redox chemistry associated with metallointercalators bound to DNA.

Item Type:Article
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URLURL TypeDescription Information
Kelley, Shana O.0000-0003-3360-5359
Barton, Jacqueline K.0000-0001-9883-1600
Alternate Title:Synthesis and Spectroelectrochemistry of Ir(bpy)(phen)(phi)3+, a Tris(heteroleptic) Metallointercalator
Additional Information:© 2001 American Chemical Society. ReceiVed April 6, 2001. Publication Date (Web): August 30, 2001. We are grateful to the NIH (GM33309) for their financial support of this research. We also thank N. J. Turro for helpful discussions.
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Issue or Number:20
Record Number:CaltechAUTHORS:20160129-155405893
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Official Citation:Synthesis and Spectroelectrochemistry of Ir(bpy)(phen)(phi)3+, a Tris(heteroleptic) Metallointercalator Christine Stinner, Matthew D. Wightman, Shana O. Kelley, Michael G. Hill, and, and Jacqueline K. Barton Inorganic Chemistry 2001 40 (20), 5245-5250 DOI: 10.1021/ic010376t
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64104
Deposited By: George Porter
Deposited On:02 Feb 2016 20:41
Last Modified:10 Nov 2021 23:25

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