Electrochemisty and electrogenerated chemiluminescence of Ru(phen)₂dppz(BF₄)₂ both free and intercalated into DNA
Abstract
Ruthenium (II) bisphenanthroline dipyridophenazine, Ru(phen)2dppz2+, exhibits
first oxidation and reduction voltammetric responses which correlate well with the UVvis
spectroscopy and are typical to the compound class. The complex proves energy
sufficient for electrogenerated chemiluminescence (ECL), and does so in aqueous media
with co-reactants, also similar to its phenanthroline and bipyridine analogues. However,
this behavior is curious since this compound’s aqueous photoluminescence (PL) is
undetectable but exhibits ‘light switch’ behavior upon intercalation into both calf thymus
DNA and other polynucleotides in that the PL greatly increases. The ECL of both the
free and intercalated complex is presented as well as scanning electrochemical
microscopy (SECM) studies to understand the complex’s kinetic behavior in water upon
oxidation. In an effort to understand the SECM results, the program COMSOL
Multiphysics is used to model the EC’ (catalytic) following reaction. The simulation
results are validated using the ferrocyanide/cysteine system, which is known to exhibit
the EC’ mechanism.
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