Synthesis, characterization and DNA binding and cleavage properties of ruthenium(II) complexes with various polypyridyls

Figures & data

Scheme 1.  The synthesis of the Ru^II complexes (1, R = Br; 2, R = F; 3, R = OCH₃).

Table 1.  Electronic spectral data for the ruthenium(II) complexes.

Complexes	λmax/nm (ϵ/dm^3 mol^−1 cm^−1)
	π → π*	MLCT
1	285.5 (46,900), 308 (48,900)	490.5 (20,050)
2	282.5 (66,400), 310 (59,650)	488.5 (24,400)
3	282.5 (43,600), 308 (56,550)	492.0 (22,350)

Figure 1.  Electronic absorption spectra of (A) [Ru^II(4-bptpy)(dmphen)Cl]ClO₄, (B) [Ru^II(4-fptpy)(dmphen)Cl]ClO₄ and (C) [Ru^II(4-mptpy)(dmphen)Cl]ClO₄ with increasing amount of DNA in phosphate buffer (Na₂HPO₄/NaH₂PO₄, pH 7.2). [Complex] = 20 µM, [DNA] = 0–16.6 µM with incubation period of 15 min at 37°C. Plots of [DNA]/(ϵ_a− ϵ_f) versus [DNA] for the titration of DNA with Ru^II complexes.

Table 2.  Electronic absorption data upon addition of Herring Sperm DNA.

Complex	λmax (nm)			Hypochromism H^a (%)	Binding constant Kb (M^−1)
	Free	Bound	Δλ
1	490.5	503.5	13	23.9	6.32 × 10^5
2	488.5	488.5	0	5.6	6.57 × 10^3
3	492.0	494.0	2	13.3	1.85 × 10^4

^aH% = 100 × (A_free − A_bound)/A_free.

Figure 2.  Effect on relative viscosity of DNA under the influence of increasing amount of ethidium bromide and complexes at 27 ± 0.1°C in phosphate buffer (Na₂HPO₄/NaH₂PO₄, pH 7.2).

Figure 3.  Agarose gel (1%) of pUC19 (100 µg/mL) incubated for 2 h at 37°C in TE buffer (pH 8) with increasing concentrations of the [Ru^II(4-bptpy)(dmphen)Cl]ClO₄. Lane 1, DNA control; lane 2, RuCl₃ (100 µM); lanes 3–8, [Ru^II(4-bptpy)(dmphen)Cl]ClO₄ complex: 25, 75, 125, 200, 300 and 400 µM, respectively.

Figure 4.  The percentage of SC, OC and L forms of DNA produced by various concentration of [Ru^II(4-bptpy)(dmphen)Cl]ClO₄ complex.

Figure 5.  Agarose gel (1%) of pUC19 (100 µg/mL) at 37°C in TE buffer (pH 8) with 200 µM [Ru^II(4-bptpy)(dmphen)Cl]ClO₄ complex for increasing reaction time. Lane 1, DNA control; lanes 2–8: 15, 30, 60, 90, 120, 180 and 240 min, respectively.

Figure 6.  The percentage of SC, OC and L forms of DNA produced by 200 µM of [Ru^II(4-bptpy)(dmphen)Cl]ClO₄ complex at different time.

Figure 7.  Agarose gel (1%) of pUC19 (100 µg/mL) at 37°C in TE buffer (pH 8) with 200 µM compounds incubated for 4 h. Lane 1, DNA control; lane 2, RuCl₃; lane 3, [Ru^II(4-bptpy)(dmphen)Cl]ClO₄; lane 4, [Ru^II(4-fptpy)(dmphen)Cl]ClO₄; lane 5, [Ru^II(4-mptpy)(dmphen)Cl]ClO₄.