Organometallics
ARTICLE
Figure 1. Examples of ruthenium-based anticancer complexes.
layer was extracted with DCM (3 Â 15 mL). The combined organic
extracts were dried over anhydrous MgSO4 and filtered, and the solvent
was removed in vacuo. The product was purified by flash column chro-
matography with an eluent of ethyl acetate/hexane (1:10). Yield: 284.1
mg (81.2%). 1H NMR (CDCl3) δ/ppm: 2.17 (t, 2H, ÀCH2CH2CHO),
2.41À2.50 (m, 4H, dCHCH2, ÀCH2CHO), 2.53À2.56 (m, 2H, d
CH-CH2), 5.31À5.32 (m, 1H, dCH-Cquat), 5.53À5.61 (m, 2H, ÀCHd
known to be explosive under heating.) 3b (30 mg, 0.04 mmol) was
stirred with a suspension of silver oxalate (0.01 mmol) in water (12 mL)
at rt for 24 h. The crude solution was filtered through Celite and dried by
rotary evaporation. The residue was redissolved in methanol (12 mL)
and stirred with pta (13 mg, 0.08 mmol) for 2 h at rt. The reaction
mixture was concentrated, and diethyl ether was added to precipitate a
yellow solid. The precipitate was washed with diethyl ether (2Â) and
1.10 (t, 6H, ÀOCH2CH3), 3J = 7.07 Hz, 1.91À1.97 (m, 2H, PhCH2-
CH2CHÀ), 2.45 (t, 2H, PhCH2CH2CH), 3.48À3.72 (m, 4H,À
OCH2CH3), 4.13 (s, 6H, ÀPCH2NÀ), 4.52 (m, 6H, ÀNCH2NÀ), 4.72
(masked by solvent, 1H, PhCH2CH2CHÀ), 5.53 (m, 1H, Ph-Hpara),
5.83À5.90 (m, 4H, Ph-H). 31P{1H} NMR (CD3OD) δ/ppm: À31.1.
ESI-MS (m/z): 578 [M + Na]+, 1132 [2M + Na]+.
X-ray Diffraction Studies. X-ray data were collected with a Bruker
AXS SMART APEX diffractometer using MoÀKα radiation at 223(2) K
with the SMART suite of Programs.10 Data were processed and correc-
ted for Lorentz and polarization effects with SAINT,11 and for absorp-
tion effects with SADABS.12 Structural solution and refinement were
carried out with the SHELXTL suite of programs.13 The structure was
solved by direct methods to locate the heavy atoms, followed by dif-
ference maps for the light, non-hydrogen atoms. All non-hydrogen
atoms were generally given anisotropic displacement parameters in the
final model. All H atoms were put at calculated positions. A summary of
the crystallographic data is given in Table 2.
3
1
CHÀ), 9.64 (t, 1H, ÀCHO), J = 1.73 Hz. 13C{1H} NMR (CDCl3)
dried in vacuo. Yield: 35.7 mg (80.4%). H NMR (CD3OD) δ/ppm:
δ/ppm: 26.3 (ÀCH2CH2CHO), 28.6, 29.05 (dienyl-CH2À), 41.0
(ÀCH2CH2CHO), 118.7, 123.5, 123.7 (dienyl-CdCH), 132.9 (dienyl-
Cquat), 201.8 (ÀCHO).
Preparation of [η6-(3,3-Diethoxypropylbenzene)RuCl2]2
(3b). RuCl3 xH2O (58.3 mg, 0.21 mmol) and 2 (143 mg, 1.05 mmol)
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in ethanol (12 mL) was refluxed at 100 °C under a N2 atmosphere for
4 h. The reaction mixture was concentrated in vacuo, and diethyl ether
was added to yield an orange precipitate. The precipitate was washed
with diethyl ether (2Â) and dried in vacuo. Yield: 73.0 mg (90.3%). 1H
NMR (CDCl3) δ/ppm: 1.15 (t, 6H, ÀOCH2CH3) 3J = 6.99 Hz,
1.86À1.93 (m, 2H, PhCH2CH2CHÀ), 2.62 (t, 2H, PhCH2CH2CHÀ),
3.39À3.65 (m, 4H, ÀOCH2CH3), 4.47 (t, 1H, PhCH2CH2CHÀ), 3J =
5.43 Hz, 5.39 (d, 2H, Ph-Hortho), 5.56À5.60 (m, 1H, Ph-Hpara), 5.62À
5.66 (m, 2H, Ph-Hmeta); single crystals from diethyl ether into DCM
solution.
Preparation of [η6-(3,3-Dimethoxypropylbenzene)RuCl2]2
(3a). The same procedure as complex 3a was carried out using 2 (141.1
g, 1.04 mmol) and RuCl3 xH2O (41.5 mg, 0.15 mmol) in methanol,
Aquation Studies by UVÀvis Absorption Spectroscopy. A
solution of 4 (0.2 mM, 1 mL) was added to a quartz cuvette, and its UV
absorbance was measured at 1 min intervals from 280 to 580 nm. The
reaction was repeated using 150 mM NaCl and 1 mM GSH, and 5 with 1
or 10 mM GSH.
pH-Dependent Stability Studies. Complex 5 (100 mM) was
dissolved in 0.2 M phosphate buffered solutions of pH 5.8, 6.0, 7.0, and
8.0 (0.5 mL) and diluted with D2O (500 μL). The solutions were left at
rt for 48 h and analyzed by 1H NMR.
Conjugation Studies with o-Benzylhydroxylamine. Com-
plexes 4 (1.0 mg, 1.9 μmol) and 5 (1.0 mg, 1.8 μmol) in water (1 mL)
were treated with HCl (10 mM, 1 mL) for 1 h. The solution was adjusted
to pH 6.0 using a 100 mM K2CO3 solution, and o-benzylhydroxylamine
in DMF (0.33 mg, 2.7 μmol) was added to the reaction mixture. The
reaction was stirred at rt for 2 h and analyzed by ESI-MS.
Cell-Based Binding Assays. HEK cells were plated on a 96-well
microplate (Nunc) at a density of 10 000 cells per well in complete
DMEM media. After 24 h, the cells were incubated with a solution of 4 in
DMEM (1 mM, 100 μL). After incubating for 6 h, the solution was
removed and the cells washed with PBS (2 Â 100 μL). Cold ethanol
(100 μL) was added to each well, and the plate was incubated at À20 °C
for 5 min. The cells were washed with PBS (2 Â 100 μL), and HCl
solution (10 mM, 100 μL) was added to each well. The plate was incu-
bated at rt for 1 h. After washing with PBS (2 Â 100 μL), AlexaFluor488
3
yielding an orange powder. Yield: 28.1 mg (52.1%). 1H NMR (CDCl3)
δ/ppm: 1.84À1.91 (m, 2H, PhCH2CH2CHÀ), 2.60 (t, 2H, PhCH2-
CH2CHÀ), 3.27 (s, 6H, ÀOCH3), 4.34 (t, 1H, PhCH2CH2CHÀ), 5.38
(d, 2H, Ph-Hortho), 5.56À5.60 (m, 1H, Ph-Hpara), 5.63À5.64 (m, 2H,
Ph-Hmeta); single crystals from diethyl ether into DCM solution.
Preparation of [η6-(3,3-Diethoxypropylbenzene)RuCl2-
(pta)] (4). pta (16.5 mg, 0.01 mmol) was added to a solution of 3b
(40 mg, 0.05 mmol) in DCM/MeOH (1:1) and refluxed at 60 °C for
2 h. The crude reaction mixture was concentrated, and the product was
precipitated with diethyl ether. The precipitate was washed with diethyl
ether (3Â) and dried in vacuo. Yield: 53.4 mg (94.5%). 1H NMR
(CDCl3) δ/ppm: 1.18 (t, 6H, ÀOCH2CH3), 1.91À1.96 (m, 2H,
PhCH2CH2CHÀ), 2.58 (t, 2H, PhCH2CH2CH), 3.44À3.69 (m,
2H, ÀOCH2CH3), 4.35 (s, 6H, PCH2N), 4.51À4.55 (m, 7H, NCH2N,
PhCH2CH2CHÀ), 5.21À5.55 (m, 5H, Ph-H). 31P{1H} NMR (CDCl3)
δ/ppm: À33.0. ESI-MS (m/z): 559 [M + Na]+, 502 [M À Cl]+; single
crystals from diethyl ether into chloroform solution.
Preparation of [η6-(3,3-Diethoxypropylbenzene)Ru(C2O4)-
(pta)] (5). A 1 M silver nitrate solution (0.24 mL, 0.24 mmol) was
added dropwise to an aqueous solution of sodium oxalate (17 mg,
0.12 mmol) and left to stir for 10 min. The white precipitate was isolated
by centrifugation and washed with water (3 Â 1 mL). The isolated silver
oxalate was used as-is without drying. (Caution! Dry silver oxalate is
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dx.doi.org/10.1021/om200783r |Organometallics 2011, 30, 5965–5971