A R T I C L E S
Ardo et al.
indicated commercial suppliers: dichloro(p-cymene)ruthenium(II)
a large beaker containing ice and water, which was continuously
stirred, obtaining a dark solution containing a yellowish green
precipitate. The precipitate was vacuum filtered and washed with
water several times. The yellowish powder obtained was dissolved
in aqueous potassium hydroxide. The blue-green insoluble powder
was filtered off, and the filtrate was acidified with concentrated
hydrochloric acid, forming a white precipitate, which was filtered
and washed with water, followed by diethyl ether. The white solid
product was dried under vacuum to obtain the title compound, which
was used without further purification (7.2 g, 74% yield).
t
dimer (Aldrich); 4,4′,4′′-tert-butyl-2,2′,2′′-terpyridine ( Bu
3
tpy; Al-
drich); 4,4′-di-tert-butyl-2,2′-bipyridine (dtb; Aldrich); 4,4′-dimeth-
yl-2,2′-bipyridine (Aldrich); 4,4′-dinonyl-2,2′-dipyridyl (dnb; Al-
drich); ruthenium(III) chloride hydrate (Aldrich), potassium
thiocyanate (Acros); lithium chloride (Fisher); 1-methylimidazole
(
&
Aldrich, 99%); 1-iodopropane (Aldrich, 99%); acetonitrile (Burdick
Jackson, spectrophotometric grade); toluene (OmniSolv, 99.99%);
lithium perchlorate (Aldrich, 99.99%); n-tetrabutylammonium per-
chlorate (TBAP; Fluka, >99.9%); n-tetrabutylammonium chloride
26
(
(
TBACl; Sigma Aldrich, 98%); n-tetrabutylammonium iodide
TBAI; Aldrich, >99% or Fluka, >98%); phenothiazine (PTZ;
4,4′-Diethyl ester-2,2′-bipyridine (deeb). To 36 mL of thionyl
chloride (SOCl ) at room temperature was added dcb (7.2 g, 29.5
2
Aldrich, >98%); magnesium(II) perchlorate (Aldrich, reagent grade);
copper(II) perchlorate hexahydrate (Alfa Aesar, reagent grade);
silver nitrate (Bioanalytical Scientific Instruments, Inc.); guanidine
thiocyanate (Sigma, >99%); hydrochloric acid (Fisher Scientific,
mmol). The mixture was refluxed overnight until the solution
clarified. The excess thionyl chloride was removed by rotary
evaporation yielding the acid chloride intermediate. To the solid
residue was added 200 mL of absolute ethanol (anhydrous), and
the mixture was refluxed overnight. Half of the ethanol was
removed, and the resulting precipitate was collected by vacuum
filtration. The crude product was recrystallized using absolute
3
7.2% aqueous solution); argon gas (Airgas, >99.998%); nitrogen
gas (Airgas, >99.999%); oxygen gas (Airgas, industrial grade);
titanium(IV) isopropoxide (Sigma-Aldrich, 97%); zirconium(IV)
propoxide (Aldrich, 70 wt % solution in 1-propanol); SnO
solution (Alfa Aesar, 15% in water); fluorine-doped SnO
glass (FTO; Hartford Glass Co., Inc., 2.3 mm thick, 15 Ohm/0);
2
colloidal
ethanol yielding the pure white title compound (7.0 g, 79% yield).
2
-coated
1
H NMR (300 MHz, CDCl
3
): δ 8.95 (d, J ) 1.5 Hz, 2H), 8.87 (d,
J ) 5.1 Hz, 2H), 7.92 (dd, J
1
) 5.1 Hz, J ) 1.5 Hz, 2H), 4.46 (q,
2
microscope slides (Fisher Scientific, 1 mm thick); and polished CaF
windows (International Crystal Laboratories, 2 mm thick).
2
+
J ) 7.2 Hz, 4H), 1.45 (t, J ) 7.2 Hz, 6H). EI-MS: m/z 300 [M] ,
+
+
2
55 [M - OC
2
H
5
] , 228 [M - COOC
2
H
5
] base peak, 200 [M -
Preparations. The following ligands and metal complexes were
+
COOC - C
2
H
5
2
H
5
] .
prepared by adaptation of relevant literature procedures: 4,4′-
t
[
Ru( Bu
nium(II) dimer (109 mg, 0.18 mmol) and Bu
3 3 3
C(CH ) ) -2,2′:6′,2′′-terpyridine; 145 mg, 0.36 mmol) were dis-
3
tpy)(dcb)(NCS)](PF
6
).
Dichloro(p-cymene)ruthe-
2
5
dicarboxy-2,2-bipyridine (dcb), 4,4′-diethyl ester-2,2′-bipyridine
t
3
tpy (4,4′,4′′-
2
6
27
28
(
[
deeb),
Ru(dtb)
cis-Ru(DMSO)
(deeb)](PF ) .
6 2
4
Cl
2
,
cis-Ru(dtb)
2
Cl
2
· 2H
2
O,
and
(
2
9
2
Z907 was synthesized precisely as the
solved in 50 mL of DMF. The solution was heated to 60 °C under
30,31
published one-pot procedure departing from [Ru(p-cymene)Cl
2 2
] .
argon in the dark for 4 h with constant stirring. The dcb (88 mg,
The other sensitizers employed were available from previous
0
.36 mmol) ligand was added, and the temperature was increased
to 140 °C, which was maintained for an additional 4 h. Next, an
excess amount of NH NCS (411 mg, 5.4 mmol) was added to the
reaction mixture, which was maintained at 140 °C for an additional
h. After the reaction mixture was cooled to room temperature,
most of the solvent was removed by using a rotary evaporator
connected to a vacuum pump. Saturated aqueous NH PF solution
3
2
studies: [Ru(bpy)
2
(dcb)](PF
6
)
2
,
where bpy is 2,2′-bipyridine,
33 34
[
Ru(bpy)
Os(bpy)
2
(4-CH
6 2
(deeb)](PF ) .
3
-4′-COOH-bpy)](PF
6 2
) ,
[Ru(deeb)
3
](PF
)
6 2
and
4
3
5
1
13
[
2
H NMR and C NMR spectra were
recorded on a Bruker Avance 300 (300 MHz) or Avance 400 (400
MHz) Fourier transform NMR spectrometer. MALDI-TOF mass
spectra were measured using a Bruker-Daltonics Omniflex spec-
trometer. The attenuated total reflectance (ATR) Fourier transform
infrared (FTIR) spectra of reaction products were recorded on a
Thermo Scientific Nicolet IR200 spectrophotometer.
4
4
6
was added dropwise to the DMF residue producing an insoluble
solid, which was collected on a sintered glass crucible by suction
filtration. The crude compound was dissolved in methanol contain-
ing a few drops of chloroform. This solution was passed through
a Sephadex LH-20 column using methanol as the eluent. The
2
5
4
,4′-Dicarboxy-2,2′-bipyridine (dcb). In a 500 mL round-
bottom flask equipped with a magnetic stirrer, 4,4′-dimethyl-2,2′-
bipyridine (8 g, 0.04 mol) was dissolved in 100 mL of sulfuric
acid at room temperature. The solution was cooled to 0 °C in an
ice bath, and chromium trioxide (26 g, 0.26 mol) was added in
small portions over 2 h with continuous stirring. The mixture turned
red first, then bluish green. After the addition of chromium trioxide
was complete, the mixture was heated to 75 °C and maintained at
this temperature for 4 h. Subsequently, the mixture was stirred at
room temperature for 10 h. The reaction mixture was poured into
primary band was collected and concentrated (291 mg, 85% yield).
1
H NMR (300 MHz, CHCl
3
+ CD
H), 9.10 (s, 1H), 8.88 (s, 1H), 8.32 (dd, J
H), 8.26 (s, 2H), 8.11 (s, 2H), 7.43 (d, J ) 6 Hz, 1H), 7.31 (d, J
6 Hz, 2H), 7.16 (dd, J ) 1.8 Hz, J ) 6 Hz, 2H), 7.05 (d, J )
.7 Hz, 1H), 1.60 (s, 9H), 1.29 (s, 18H). C NMR (75 MHz, CHCl
CD OD): δ 167.46, 166.81, 163.43, 161.71, 158.75, 158.46,
3
OD): δ 9.77 (d, J ) 5.7 Hz,
1
1
)
5
1
) 1.5 Hz, J ) 6 Hz,
2
1
2
13
3
+
3
1
1
3
57.39, 157.05, 153.22, 152.19, 151.30, 143.55, 141.25, 134.45,
27.03, 126.48, 125.42, 123.76, 123.71, 121.60, 120.53, 36.75,
5.92, 31.07, 30.52. MALDI-MS (TOF): m/z 805.44 (M - PF ).
6
+
-
(
(
25) Garelli, N.; Vierling, P. J. Org. Chem. 2002, 57, 3046–3051.
26) Sprintschnik, G.; Sprintschnik, H. W.; Kirsch, P. P.; Whitten, D. G.
J. Am. Chem. Soc. 2002, 99, 4947–4954.
FTIR (ATR): 2963 (s), 2874 (m), 2102 (s), 1716 (s), 1610 (s), 1541
(m), 1459 (m), 1367 (s), 1251 (s), 831 (vs).
(27) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans.
28
cis-Ru(dtb)
2
Cl
2
·2H
2
O. RuCl
3
2
·3H O (0.52 g, 2.0 mmol), dtb
1
973, 204–209.
28) Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg. Chem. 2002, 17,
334–3341.
(
4,4′-(C(CH ) ) -2,2′-bipyridine; 1.07 g, 4.0 mmol), and an excess
3 3 2
(
amount of lithium chloride (0.56 g, 13.3 mmol) were refluxed in 5
mL of DMF under argon in the dark for 6 h. After the reaction
mixture was cooled to room temperature, ∼15 mL of acetone was
added, and the resultant solution was put into the refrigerator
overnight. The mixture was filtered under vacuum to obtain a dark
green-black powder, which was washed with water and diethyl ether
3
(
(
29) Liu, F.; Meyer, G. J. Inorg. Chem. 2005, 44, 9305–9313.
30) Wang, P.; Zakeeruddin, S. M.; Moser, J. E.; Nazeeruddin, M. K.;
Sekiguchi, T.; Gr a¨ tzel, M. Nat. Mater. 2003, 2, 402–407.
31) Nazeeruddin, M. K.; Zakeeruddin, S. M.; Lagref, J. J.; Liska, P.;
Comte, P.; Barolo, C.; Viscardi, G.; Schenk, K.; Gr a¨ tzel, M. Coord.
Chem. ReV. 2004, 248, 1317–1328.
(
+
(
(
32) Morris, A. J.; Meyer, G. J. J. Phys. Chem. C 2008, 112, 18224–
(1.04 g, 70% yield). MALDI-MS (TOF): m/z 708.97 [M] , 673.47
-
+
1
8231.
[M - Cl ] .
Ru(dtb) (deeb)](PF
deaerated ethanol-water (30 mL, 1:1) were added cis-
Ru(dtb) Cl O (343 mg, 0.46 mmol) and deeb (141 mg, 0.47
2
9
33) Meyer, T. J.; Meyer, G. J.; Pfennig, B. W.; Schoonover, J. R.;
Timpson, C. J.; Wall, J. F.; Kobusch, C.; Chen, X.; Peek, B. M.
Inorg. Chem. 2002, 33, 3952–3964.
34) Gardner, J. M. Thesis, Johns Hopkins University, 2009.
35) Higgins, G. T.; Bergeron, B. V.; Hasselmann, G. M.; Farzad, F.;
Meyer, G. J. J. Phys. Chem. B 2006, 110, 2598–2605.
[
2
6
)
2
.
To a round-bottom flask containing
2
2
·2H
2
(
(
mmol). The mixture was refluxed under argon in the dark for 20 h.
The solvent was removed by rotary evaporator under vacuum. Cold
6
698 J. AM. CHEM. SOC. 9 VOL. 132, NO. 19, 2010