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Updated: Jan 16, 2026
The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes
Published on: April 10, 2015
Intercalative binding, light-switch behavior, and theoretical analysis of Ru(bpy)2dppz-BTDZ]2+: A
Mariana O T Nogueira1, Pedro Henrique L da Silva2, Ana Carolina C do Nascimento2
1Laboratory of Molecular Modeling Applied to the Chemical and Biological Defense (LMCBD), Military Institute of Engineering, Praça General Tibúrcio 80, 22290-270 Rio de Janeiro, RJ, Brazil; Department of Inorganic Chemistry, Universidade Federal Fluminense, 24020-140, Niterói, Rio de Janeiro, Brazil.
None:
The new ruthenium(II) polypyridyl complex [Ru(bpy)₂dppz-BTDZ]2+, featuring a thiadiazole-substituted dppz ligand, was synthesized and characterized to investigate its DNA-binding and photophysical properties. Its interaction with calf thymus DNA (Ct-DNA) was studied through UV-visible and emission spectroscopy, competitive binding assays with ethidium bromide (EB), anionic quenching with K4[Fe(CN)6], viscosity and molecular modeling. The results indicate that the complex intercalates into DNA, with a binding constant (Kb) of 6.57 ± 0.9 × 106 M-1 and has a 7 % enhancement in the light-switch effect compared to [Ru(bpy)₂dppz]2+. DFT calculations characterized the excited states, which were compared to those of [Ru(bpy)₂dppz]2+. The presence of the thiadiazole group promotes mixing of MLCT states. Franck-Condon analysis of emission spectra in MeCN, water, and DNA allowed for the estimation of the excited-state free energy. In water, the emissive bright state lies approximately 1300 cm-1 higher than in DNA and approximately 1100 cm-1 higher than in MeCN. This energy trend is consistent with the light-switch behavior observed in this class of complexes. Moreover, the bright-state energies correlated very well with all the observed lifetimes. Docking and molecular dynamics simulations revealed stable intercalative binding in the DNA minor groove, with the Δ-isomer showing enhanced stability.
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