Synthesis, characterization, DNA-binding properties and electronic structure (DFT) of ruthenium oligopyridine complexes
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Christopoulos, K.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Christopoulos, K.
(EN)
The complexes of the general formulae [Ru(terpy)(dcbpy)X](q) (dcbpy = 4,4'-dicarboxy-2,2'-bipyridine; X = Cl(-), 1; NO(+), 2: No(2)(-), 3: q = 1+, 3+ and 1-, respectively) have been synthesized and characterized. The DNA binding properties of structurally similar complexes [Ru(terpy)(dcbpy)NO(2)](-), 3, [Ru(terpy)(4-CO(2)-4'-Mebpy)NO(2)], 4, and [Ru(terpy)(bpy)NO(2)](+), 5, were studied, and their DNA affinities (K(b)) were calculated as 6 +/- 0.3 x 10(4) M(-1), 8 +/- 1.1 x 10(4) M(-1) and 9.7 +/- 0.02. 10(6) M(-1). The structural and spectroscopic properties of complexes 3-5 were investigated by DFT and TD DFT electronic structure calculations. The equilibrium geometries of complexes 3-5 in vacuum correspond to a distorted octahedral stereochemistry. The high-lying peaks of the absorption spectra of the complexes, ranging from 440 to 529 nm, are assigned to MLCT/LLCT transitions. These transitions are red-shifted upon adding carboxy substituents to the bipyridine ligand while the low-lying LLCT transitions, absorbing at 779 and 659 turn, are blue-shifted. Noteworthy is the excellent agreement of the TD DFT simulated absorption spectra in aqueous solution with the experimental ones. (C) 2008 Elsevier B.V. All rights reserved.
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