Synthesis, and Acid–Base and DNA-Binding Properties of a Thiophen-Appended Ruthenium Complex

Abstract

2-(5-Phenylthiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (Hptip) and its Ru II complex [Ru(bpy) 2 (Hptip)](PF 6 ) 2 (where bpy ¼ 2,2 0 -bipyridine) have been synthesized and characterized by elemental analysis, 1 H NMR spectroscopy, and mass spectrometry. The acid-base properties of the complex were studied by UV-visible and luminescence spectrophotometric pH titrations, and ground-and excited-state acidity ionization constants were derived. The DNAbinding properties of [Ru(bpy) 2 (Hptip)](PF 6 ) 2 were also investigated by means of UV-vis and emission spectroscopy, salt effects, steady-state emission quenching by [Fe(CN) 6 ] 4À , DNA competitive binding with ethidium bromide, DNA melting experiments, and viscosity measurements. Density functional theoretical calculations were also carried out in order to understand the DNA binding properties.

Off–on–off pH luminescence switching and DNA binding properties of a free terpyridine-appended ruthenium complex

“…In contrast, the electron in excited [Ru(bpy) 2 (HL 1 )] 2+⁎ was localized on bpy rather than on HL 1 , which typically leads to comparable or increased excited-state acidity with respect to the ground-state acidity. This behavior is similar to the behaviors exhibited by the imidazolecontaining Ru(II) complexes we and others have previously reported [39][40][41][42][43][44][45]50]. and could be rationalized by the absence of a Coulombic effect between the imidazole ring on H 2 L 1 and the metal center as evidenced by experimental and theoretical studies on an analogous Ru(II) complex of [Ru(bpy) 2 (PhenImHPh)] 2+ (PhenImHPh = 2-(3,5-di-tert-butylphenyl)imidazo[4,5-f]-[1,10]phenanthroline) [50].…”

“…1. The pK a1 and pK a3 values fall within the corresponding pK a ranges of 0.31-2.48 and 8.21-9.65 that we previously reported for the acid ionization constant values of protonated imidazolium on analogous Ru(II) complexes [37][38][39][40][41][42][43][44][45]. The value of pK a2 agrees well with pK a = 3.55-4.65 for the uncoordinated peripheral pyridyl of the terpyridine on 4-phosphonato-2,2′:6′,2″-terpyridine [46] and dimethylaminostyrylterpyridine [47].…”

“…In addition, the T m value increased linearly by 1.05, 3.02, and 8. [60], and falls into the rather broad ΔT m range of 5.9 to 19.3°C previously reported for analogous Ru(II) complex-based DNA intercalators under identical experimental conditions with [Ru]/DNA = 0.10 [37][38][39][40][41][42][43][44][45]. In addition, this ΔT m value is similar to a ΔT m value of 9.3°C that we have recently reported for a Ru(II) complex DNA binder with a mixed binding mode involving classic intercalation plus partial intercalation [23], and greater than only small T m increases of ≤ 2 and 3°C previously reported for an organic DNA binder of 1,4,7,10-tetraazacyclododecane appended with two anthracenyl moieties that showed mixed binding modes of partial intercalator and groove binding [61], and partially intercalative Ru(II) complex of [Ru(H 2 PDTA)(phen)]Cl (H 4 PDTA = propylene-1,2-diaminetetra-acetic acid) [32], respectively.…”

DNA Binding and Photocleavage Properties, Cellular Uptake and Localization, and in-Vitro Cytotoxicity of Dinuclear Ruthenium(II) Complexes with Varying Lengths in Bridging Alkyl Linkers

“…All of the calculations were performed with the Gaussian 98 quantum chemistry program package . Full geometry optimization computations were performed by applying the DFT-B3LYP method , and the LanL2DZ basis set and assuming the singlet state for the ground state of the complexes. − , To vividly depict the detail of the frontier molecular orbital interactions, the stereographs of some related frontier molecular orbitals of the complexes were drawn with Gaussview based on the computational results.…”

Highly Sensitive and Selective Difunctional Ruthenium(II) Complex-Based Chemosensor for Dihydrogen Phosphate Anion and Ferrous Cation

“…Of the transition metal complexes that have been studied, ruthenium polypyridyl complexes are one of the most investigated chemical systems due to their remarkable chemical stability and intriguing ground- and excited-state photophysical and redox properties. Taking advantage of these favorable properties, optical and electrochemical sensors based on the ruthenium polypyridyl complexes have been rapidly developed for the detection of anions and transition metal cations, , but the development of highly sensitive and selective multifunctional sensors for both cations and anions still faces a great challenge …”