Ϫ1
dioxane containing 4% v/v water. Selenium oxide (7.5 g, 68
mmol) was added, the mixture heated to reflux for 2 h and then
filtered through Celite while hot. 4,7-Diformyl-1,10-phen-
anthroline was separated from the cold filtrate as yellow crystals
2 cm with the samples in compressed KBr pellets. UV-vis
spectra were measured with a Shimadzu UV3101PC spec-
Ϫ5
trometer. An aqueous stock solution (3 × 10 M) was pre-
pared, containing 0.1 M NaClO , and the initial pH was
4
(
2.2 g, 65%) and recrystallized from tetrahydrofuran. The
adjusted to 10.4 by adding 0.1 M NaOH solution. The pH
dependent UV-vis spectra were measured 5 min after the add-
3
dialdehyde (0.5 g, 2.0 mmol) in 10 cm of 70% nitric acid was
heated under reflux for 3 h, then poured onto ice, and the pre-
cipitated solid (0.23 g, 43%) recrystallized from methanol
(
6
ition of HClO to a solution.
4
Corrected emission spectra were obtained using a Hitachi
Co. F-4500 spectrophotometer. Spectra at 77 K were measured
in 4:1 (v/v) ethanol–methanol glasses immersed in liquid N2.
All solutions were prepared to give approximate concentration
Found: C, 62.57; H, 2.97; N, 10.36. Calc. for C H NO : C,
7 4 2
2.69; H, 3.01; N, 10.44%).
Ϫ5
cis-Dichlorobis(4,7-dicarboxy-1,10-phenanthroline)ruthen-
ium(II) 1. RuCl ؒ3H O (52 mg) was dissolved in DMF under Ar.
of 1 × 10 M. All samples for emission measurements were
purged with nitrogen stream. The emission lifetimes were
measured by exciting samples with a 5 ns laser pulse at 500 nm
from an optical parametric oscillator (Sirelite OPO) pumped
at 355 nm by a Nd:YAG laser (Continum Surelite II). The
emission decay was followed on a photomultiplier tube
(Hamamatsu R928).
A BAS-100 electrochemical analyzer (Bioanalytical Systems)
was used to perform cyclic voltammetry. A conventional three
electrodes system was used for the electrochemical measure-
ment with a platinum wire as a counter electrode, a carbon and
platinum disk (1.5 mm diameter embedded in Teflon) as a work-
3
2
To this was added compound I as a solid (103 mg). The mixture
was refluxed with vigorous stirring, in the dark and an argon
atmosphere. After refluxing for 3 h the reaction mixture was
allowed to cool to room temperature and filtered. DMF was
removed in vacuo. The resulting solid was washed with acetone–
diethyl ether (1:4) and the solid stirred in 2 M HCl aqueous
solution for 2 h and filtered through a membrane filter. After
drying, complex 1 (120 mg, 86%) was obtained (Found: C,
4
7.29; H, 2.24; N, 7.87. Calc. for C H Cl N O Ru: C, 47.47;
28 16 2 4 8
H, 2.28; N, 7.91%).
ing electrode and Ag–AgCl (saturated aqueous KCl) or Ag–
ϩ
Ag (AgNO 0.1 M, tetrabutylammonium perchlorate 0.1 M in
cis-Dicyanobis(4,7-dicarboxy-1,10-phenanthroline)ruthen-
ium(II) 2. A mixture of KCN (183 mg) and complex 1 (100 mg)
in 3:1 (v/v) DMF–water was heated to reflux under Ar for 5 h.
The solution changed from violet to orange. Then the reaction
mixture was allowed to cool and filtered. The filtrate was evap-
orated to dryness and the resulting solid dissolved in water at
pH 10. After addition of dilute HClO an orange solid was
isolated at pH 2–3, washed with water, ethanol, and anhydrous
diethyl ether, and dried in air for 1 day. The compound 2
3
acetonitrile) in contact with a KCl salt bridge as reference. Elec-
trode potential values were corrected to the SCE. Scan rates
Ϫ1
were 10–400 mV s . The cyclic voltammetry in water was
carried out in 0.1 M NaClO aqueous solution at pH 3.5. Dry
4
organic solvents (water < 0.005%) were used as received (Wako
Chem.). NBu ClO and NaClO were purchased from Fluka
4
4
4
4
Corp. and Aldrich Corp., respectively.
Photoelectrochemical measurements were performed in a
two-electrode sandwich cell configuration as previously
(
69 mg, 70%) was obtained as an orange solid (Found: C, 50.63;
2
,10,12
reported.
The geometric surface area and thickness of the
H, 2.51; N, 11.28. Calc. for C H N O RuؒH O: C, 50.92; H,
2
30
16
6
8
2
2
semiconductor film were 0.44 cm and 10 µm, respectively. A
solution of complex 4 was prepared in 1:1 (v/v) acetonitrile–
tert-butyl alcohol at a concentration of 5 × 10 M. The
.56; N, 11.80%).
Ϫ4
cis-Bis(4,7-dicarboxy-1,10-phenanthroline)dithiocyanato
3
electrolyte solution was composed of 0.5 mM 1,2-dimethyl-3-
ruthenium(II) 3. NH NCS (500 mg) was dissolved in 5 cm of
water. To this solution 30 cm of DMF were added under Ar
followed by 200 mg of complex 1 as a solid. The mixture was
refluxed in the dark for 5 h, allowed to cool and then filtered
through a membrane filter. DMF and water were removed by
4
3
propylimidazolium iodide, 20 mM I , 0.5 M 4-tert-butylpyr-
2
idine, 40 mM LiI in methoxyacetonitrile. The amount of
adsorbed ruthenium complex was determined by desorbing it
from a TiO film into a 0.01 M NaOH 1:1 (v/v) ethanol–water
2
solution and measuring its absorption spectrum.
rotary evaporation. To the resulting viscous liquid were added
1
3
0 cm of 0.05 M NaOH aqueous solution to give a dark
purple-red homogeneous solution. This was filtered through a
Results and discussion
NMR spectroscopy
membrane filter and the pH lowered to 3.5 with 0.5 M HNO to
3
give a dense precipitate. The mixture was placed in a refriger-
ator for 12 hours. After allowing it to reach room temper-
ature the solid was collected on a membrane filter by suction
The notation for the aromatic protons of cis-bis(4,7-dicarboxy-
1,10-phenanthroline)dithiocyanato ruthenium() 3 and of cis-
bis(4,4Ј-dicarboxy-2,2Ј-bipyridine)dithiocyanato ruthenium()
5 is shown below. The primes are for protons of the pyridine ring
3
filtration, washed (3 × 20 cm ) with water (pH 3.5), and air
dried. Purple solid complex 3 (198 mg, 85%) was obtained
1
(
Found: C, 47.01; H, 2.15; N, 10.64. Calc. for C H N O RuS :
not trans to SCN. The H NMR spectral data for 4,7-dicarboxy-
30
16
6
8
2
C, 47.81; H, 2.14; N, 11.15%).
1,10-phenanthroline I, cis-dichlorobis(4,7-dicarboxy-1,10-
phananthroline)ruthenium() 1, cis-dicyanobis(4,7-dicarboxy-
1,10-phenanthroline)ruthenium() 2, 3, 4,4Ј-dicarboxy-2,2Ј-
Bis(tetrabutylammonium)
cis-bis(1,10-phenanthroline-4,7-
dicarboxylate)dithiocyanato ruthenate(II) 4. 100 mg of complex
3
were dissolved in 10 ml of a 10% NBu OH aqueous solution.
4
This solution was adjusted to pH 4 by the addition of 0.1 M
nitric acid and kept in a refrigerator. The flask was allowed to
warm to room temperature, and the precipitate was collected on
a membrane filter. The yield of compound 4: 70 mg (47%).
Measurements
1
H NMR spectra were recorded by a Varian 300BB spec-
trometer. The ratio of tetrabutylammonium cation to the
ruthenate anion was estimated from an integration of proton
peaks. IR spectra measurements were performed using a
JASCO Co. FTIR 5300 spectrophotometer at a resolution of
2
818
J. Chem. Soc., Dalton Trans., 2000, 2817–2822