methoxy), 3.64-3.79 (m, 4H, piperazine), 2.80-2.96 (m, 4H, piperazine), 2.20 (s, 6H, methyl),
1.80 (s, 6H, methyl). 13C NMR (300 MHz, CDCl3; δ (ppm)): 207.4 (C-1), 50.2 (C-2), 46.0 (C-3),
144.6 (C-4), 114.5 (C-5), 118.9 (C-6), 154.5 (C-7), 55.6 (C-8), 165.9, 166.4 (C-1',1"), 124.6,
125.7 (C-2',2"), 135.0, 135.2 (C-3',3"), 128.5, 128.8 (C-4',4"), 126.2, 126.5 (C-5',5"), 150.2,
151.4 (C-6',6"), 25.3, 29.2 (C-7',7"). UV-vis; λ (nm): 273, 505, 570. IR(stretch) (υ cm-1):
1489(C−N, m), 1224(C-NC2, m), 1018(C–S, s). Anal. Calcd for C40H39N6ORuS2BF4 (%): C,
55.11; H, 4.51; N, 9.64. Found: C, 55.5; H, 4.6; N, 9.62.
Complex 2 was prepared using the same methodology as described for 1 using
cis-[Ru(DMP)2Cl2](0.419 g, 0.712 mmol), sodium salt of 4-(3-methoxyphenyl)piperazine-1-
carbodithioate (0.212 g, 0.73 mmol) and excess NaBF4 (yield: 0.45 g, 72 %). (MW = 871.78),
m.p. 239-240 °C. 1H NMR (300 MHz, CDCl3; δ (ppm)): 8.25-8.29 (dd, 3H, DMP), 8.15 (d, 1H,
J = 8.1, DMP), 7.89-7.92 (m, 4H, DMP), 7.50-7.73 (m, 4H, DMP), 7.16 (t, 1H, J = 8.4,
dtc-aromatic), 6.41-6.48 (m, 2H, dtc-aromatic), 6.35 (t, 1H, J = 2.4, dtc-aromatic), 3.77 (s, 3H,
methoxy), 3.66-3.82 (m, 4H, piperazine), 2.90-3.00 (m, 4H, piperazine), 2.21 (s, 6H, methyl),
1.73 (s, 6H, methyl). 13C NMR (300 MHz, CDCl3; δ (ppm)): 207.5 (C-1), 48.5 (C-2), 45.7(C-3),
151.6 (C-4), 103.0 (C-5), 160.6 (C-6), 105.3 (C-7), 130.0 (C-8), 109.2 (C-9), 55.3 (C-10), 166.0,
166.4 (C-1',1"), 124.6, 125.7 (C-2',2"), 134.9, 135.2 (C-3',3"), 128.5, 128.8 (C-4',4"), 126.2,
126.4 (C-5',5"), 150.2,151.4 (C-6',6"), 25.2, 29.2 (C-7',7"). UV-vis; λ (nm): 272, 505, 570.
IR(stretch) (υ cm-1): 1490(C–N, m), 1233(C-NC2, m), 1020(C–S, s). Anal. Calcd for
C40H39N6ORuS2BF4 (%): C, 55.11; H, 4.51; N, 9.64. Found: C, 55.2; H, 4.56; N, 9.67.
2.3. DNA interaction
The binding affinity with calf thymus DNA was determined by UV-visible absorption
spectroscopy in EtOH at room temperature. After recording UV-visible spectra of freshly
prepared DNA solution, absorbance (A) at 260 nm was divided with ε = 6600 M-1 cm-1, to
determine its concentration and the stock solution was stored at 4 °C. The ratio of A at 260 and
280 nm was more than 1.8, confirming protein free nature of DNA [18]. The absorption spectra
of both metal complexes were recorded between 200-800 nm. DNA-metal complex interaction
was studied by changes of A with addition of increasing concentrations of DNA [3.00-7.75 µM
(1), 2.75-10.10 µM (2)] against a constant concentration of ruthenium metal complex [17 µM (1)
and 20 µM (2)].
4