title: Effect of the Ancillary Ligands on the Spectral Properties and G-Quadruplexes DNA Binding Behavior: A Combined Experimental and Theoretical Study.
abstract: In an effort to explore the effect of ancillary ligands on the spectral properties and overall G-quadruplex DNA binding behavior, two new ruthenium(II) complexes [Ru(phen)2 (dppzi)](2+) (1) and [Ru(dmp)2 (dppzi)](2+) (2) (phen=1,10-phenanthroline, dmp=2,9-dimethyl-1,10-phenanthroline, dppzi=dipyrido[3,2-a:2',3'-c]phenazine-10,11-imidazole) were prepared. Complex 1 can emit luminescence in the absence and presence of G-quadruplexes DNA. However, with -CH3 substituent on the 2- and 9-positions of the phen ancillary ligand, no detectable luminescence is observed for complex 2 in any organic solvent or in the absence and/or presence of G-quadruplex DNA. Experimental and molecular docking studies indicated that both complexes interacted with the human telomeric repeat AG3(T2AG3)3 (22AG) G-quadruplex with the stoichiometric ratio of 1:1, but the two complexes showed different G-quadruplex DNA binding affinity. Complex 1 binds to the G-quadruplexes DNA more tightly than complex 2 does. Our results demonstrate that methyl groups on the phen ancillary ligand significantly affect the spectral properties and the overall DNA binding behavior of the complexes. Such difference in spectral properties and DNA binding affinities of these two complexes can be reasonably explained by DFT/TD-DFT calculations. This work provides guidance not only on exploring the G-quadruplexes DNA binding behavior of complexes, but also understanding the unique luminescence mechanism.
authors.affiliation: Shanghai Key Laboratory of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai (P. R. China). shishuo@tongji.edu.cn.
authors.forename: Shuo
authors.initials: S
authors.lastname: Shi
authors.affiliation: Shanghai Key Laboratory of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai (P. R. China).
authors.forename: Xing
authors.initials: X
authors.lastname: Gao
authors.affiliation: Shanghai Key Laboratory of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai (P. R. China).
authors.forename: Hailiang
authors.initials: H
authors.lastname: Huang
authors.affiliation: Shanghai Key Laboratory of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai (P. R. China).
authors.forename: Juan
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Shanghai Key Laboratory of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai (P. R. China).
authors.forename: Tianming
authors.initials: T
authors.lastname: Yao
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D007093:Imidazoles / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008962:Models, Theoretical; D015394:Molecular Structure; D010618:Phenanthrolines / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D007093:Imidazoles; D008024:Ligands; D010618:Phenanthrolines; D010619:Phenazines; C443808:dipyrido(3,2-a-2',3'-c)phenazine; C000606651:dipyrido(3,2-a-2',3'-c)phenazine-10,11-imidazole; D012428:Ruthenium; D004247:DNA; C025205:1,10-phenanthroline
keywords: G-quadruplexes; density functional calculations; ligand effects; ruthenium; spectral properties