Synthesis of highly charged ruthenium(II)-quaterpyridinium complexes: A bottom-up approach to monodisperse nanostructures

Article abstract of DOI:10.1055/s-2007-965901

Tris-homoleptic ruthenium(II)-quaterpyridine and -quaterpyridinium complexes, possessing geometric dimensions in the nanoscale, have been synthesized. The diameters range from 1.82 to 4.55 nm according to molecular modeling. The new complexes are highly charged (either +8 or +14) and luminescent and represent examples for the 'bottom-up' approach to monodisperse nanostructures. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-965901

PAPER
505
Synthesis of Highly Charged Ruthenium(II)–Quaterpyridinium Complexes:
A Bottom-Up Approach to Monodisperse Nanostructures
plexe sn Shi, Megh Raj Pokhrel, Stefan H. Bossmann*a
a
a,b
R
A
uthenium(II)–Qu
i
aterpyr
b
idinium
C
om
i
a
Kansas State University, Department of Chemistry, 111 Willard Hall, Manhattan, KS 66506-3701, USA
Fax +1(785)5326666; E-mail: sbossman@ksu.edu
b
Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal
E-mail: meghrajpokhrel2000@yahoo.com
Received 6 September 2006
terial porin channels. Furthermore, we were aiming at un-
usually high charges for ruthenium(II)–polypyridine
complexes since it can be expected that the binding of the
desired ruthenium(II)–quaterpyridinium complexes with-
Abstract: Tris-homoleptic ruthenium(II)–quaterpyridine and
–
quaterpyridinium complexes, possessing geometric dimensions in
the nanoscale, have been synthesized. The diameters range from
.82 to 4.55 nm according to molecular modeling. The new com-
1
2
0
plexes are highly charged (either +8 or +14) and luminescent and in the model porin MspA from M. smegmatis is aided by
represent examples for the ‘bottom-up’ approach to monodisperse the presence of up to 14 positive charges. Additionally,
nanostructures.
possible applications of ruthenium(II)–quaterpyridinium
Key words: 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine, ruthenium(II)–quater- complexes in the field of artificial photosynthesis will also
pyridine, ruthenium(II)–quaterpyridinium complexes, high-pressure-
assisted synthesis, photosensitizer
profit from highly charged (nano-sized) sensitizer-relay
assemblies.
17
A completely novel application for nano-sized rutheni-
um(II) complexes, representing completely monodisperse
The d block metal–4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine and
nanoparticles possessing D symmetry, is their use as cal-
1
3
-
quarterpyridinium complexes, which are also referred to
ibration materials in atomic force microscopy (AFM) ex-
periments. Due to the size of the AFM tip, this technique
exhibits a strong tendency to generate images of nano-
structures that are larger than the investigated original
sample.21 In this case, the use of precision materials for
calibration can help to eliminate this systematic error.
as 2,2¢:4,4¢¢:4¢,4¢¢¢-quaterpyridyl or tetrapyridine and tet-
1
,2
rapyridinium complexes, have gained importance dur-
ing the last two decades in several research domains: (a)
in fundamental research in inorganic chemistry as extend-
ed ligand of various d block metal cations, such as
3
3–14
15,16
iron(II), ruthenium(II),
osmium(II),
rhenium(I),
1
6
Two strategies exist for the synthesis of ruthenium(II)–
quaterpyridinium complexes: strategy A, synthesis of a
ruthenium(II)–tris(quaterpyridine) that possesses six ter-
tiary aromatic pyridine moieties, followed by quaterniza-
palladium(II), and platinum(II); (b) as redox catalysts
and electron carriers (relays) at composite electrodes;
c) as components in supramolecular assemblies;
d) as in situ luminescence sensors of pH and DNA
4,9,11
7
,11,12,14,16
(
(
8
2
5
tion of the non-ruthenium(II)-bound sp nitrogens
intercalators (with the prospect of photodynamic thera-
(Scheme 1);1 or strategy B, selective quaternization of
,17
py); and (e) advanced nonlinear optical materials.3
,13
the two terminal pyridine rings of 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-
Ruthenium(II)–quaterpyridinium complexes were suc-
cessfully employed as sensitizer-relay assemblies for the
1
photocatalytic reduction of water to dihydrogen and car-
N
N
bon dioxide to methane and other volatile hydrocarbons.17
N
N
Most recently, ruthenium(II)–quaterpyridinium complex-
es have proved to be prospective channel blockers of my-
cobacterial porins (model bacterium: Mycobacterium
Ru(DMSO)4Cl2
N
N
1
8
N
N
/ 3
smegmatis).
Ru2+
Here, we describe the synthesis of tris-homoleptic ruthe-
nium(II)–quaterpyridinium complexes. Since all tris-ho-
R
R
moleptic ruthenium(II) complexes principally exhibit D
+
N
+
3
N
1
9
symmetry, which can be slightly distorted when intricate
2
ligand systems are employed, The size (diameter) of the
R
X
desired ruthenium(II)–quaterpyridinium complexes
should range from ca. 2–5 nm in order to block mycobac-
N
N
/
3
Ru2+
SYNTHESIS 2007, No. 4, pp 0505–0514
x
x
.
x
x
.2
0
0
7
Advanced online publication: 22.01.2007
DOI: 10.1055/s-2007-965901; Art ID: M05806SS
Georg Thieme Verlag Stuttgart · New York
Scheme 1 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-Quaterpyridine complexation of ruthe-
nium(II), followed by quaternization (strategy A)
©

5
06
A. Shi et al.
PAPER
2
2
25
quaterpyridine, followed by the synthesis of the rutheni- 4-(2-chloropyridin-4-yl)pyridine and reductive coupling
um(II)–tris(quaterpyridinium) complex (Scheme 2). to give 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine (1).
The quaternization of the two external pyridine moieties Pathway A involves lithium diisopropylamide mediated
1
,26,27
of 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine (strategy B) works es- coupling of 4,4¢-bipyridine (Scheme 3);
pecially well, if methylation of the external pyridine sys- mechanism of this reaction remains unclear. Pathway B,
tems is performed. However, as indicated by preliminary involves heating and oxidative coupling of a mixture of
the general
experiments in our research group, the selectivity was less 4,4¢-bipyridine and palladium on carbon catalyst
(Scheme 4).1
3,22
than desired when larger substituents were selected.
R
+
N
R
N
N
N
+
N
N
N
LDA
THF
2
R
X
N
N
N
N
N
N
N
1
Scheme 3 Synthesis of 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine from 4,4¢-
bipyridine employing lithium diisopropylamide as coupling reagent
R
R
+
N
+
N
N
N
N
Ru(DMSO)4Cl2
Pd/C
2
N
N
/
3
N
N
Ru2+
N
1
Scheme 2 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-Quaterpyridine quaternization of ruthe-
nium(II), followed by complexation (strategy B)
Scheme 4 Synthesis of 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine from 4,4¢-
bipyridine on the surface of palladium(0) on carbon
Therefore, the work described here has been performed
according to strategy A: The syntheses of
Pathway C utilizes the tetrakis(triphenylphosphine)nick-
el(0) mediated reductive coupling of 4-(2-chloropyridin-
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine from 4,4¢-bipyridine and
4
-yl)pyridine (2) to give 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine
then of tris(4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine-N¢,N¢¢)ruthe-
nium(II) dichloride [Ru(qpy) ]Cl were optimized. Since
(
1) (Scheme 5). Examples of the successful application of
3
2
these symmetric coupling reactions of two halogenated
tris-homoleptic ruthenium(II)–quaterpyridinium com-
plexes featuring bulky groups were the desired group of
target molecules, a facile synthetic method had to be de-
veloped because thermal activation proved to be insuffi-
cient. We applied high pressure and moderate temperature
in order to achieve superior results. These experiments
aromatic systems are provided.2
8–30
N
N
N
Ni(PPh3)4
2
were guided by the simple paradigm that S 2 reactions
N
profit from high-pressure conditions due to a decrease in
their activation energy. The latter is caused by a dimin-
N
N
N
Cl
2
3
2
1
ished entropic effect at high pressure. Although organic
chemistry at high pressure has been available for many
Scheme 5 Synthesis of 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine from
2
4
years, its distinct advantages are still not widely recog- 4-(2-chloropyridin-4-yl)pyridine employing tetrakis(triphenylphos-
nized and/or utilized. It is hoped that this report will pro- phine)nickel(0) as coupling agent
vide further evidence for its usefulness as well as its easy
and safe application in an organic laboratory.
A thorough comparison of the three approaches yielded
the following yields: pathway A: 14%, which was lower
than previous results;2 pathway B: 36%, in agreement
with the previously optimized procedure;13 and C: 14%.
The latter result is predominantly caused by the low yields
obtained in the two-stage synthesis of 4-(2-chloropyridin-
First we examined the optimization of the synthesis of
5,26
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine (1). According to litera-
ture studies, there are three straightforward pathways to
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine. All three syntheses start
from 4,4¢-bipyridine. Pathways A and B lead to
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine (1) in higher yields, be-
4
2
5
4
-yl)pyridine (2). The tetrakis(triphenylphosphine)nick-
el(0) mediated reductive coupling reaction has a yield of
9%, which is typical for this coupling reaction of non-
sterically hindered electron-poor aromatic systems.
4
cause they can be completed in one stage; pathway C
comprises of three stages: the formation of the pyridinium
N-oxide, reaction with phosphorus oxychloride to give a
7
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

PAPER
Ruthenium(II)–Quaterpyridinium Complexes
507
In order to improve pathway B, we introduced a dipolar might be hindered due to competing coordination of the
aprotic solvent (DMF) to the catalytic dehydrogenation external pyridine moieties.
and coupling reaction of 4,4¢-bipyridine at palladium
Finally we optimized of the size of the ruthenium(II)–
(
10% on carbon). The presence of a solvent permits better
quaterpyridinium complexes possessing the charges +8
and +14. The optimization of the structure of the complex-
es structures was performed employing a modified MM2
control of the heat exchange during the reaction and facil-
itates the desorption of the reaction product from the pal-
3
1
ladium surface. After refluxing the mixture (at 154 °C,
2
force field. The requirements of the ruthenium(II) com-
1
3
instead of 250 °C ) for 48 hours, typical yields ranged
from 40–44%. This represents a considerable improve-
ment compared to the yield of 36%, which was obtained
without the use of a solvent. Note that the influence of ox-
ygen (air) on the coupling reaction was negligible. Anoth-
er interesting finding is that when ethylene glycol was
used as solvent, 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quaterpyridine could
only be isolated in 2–3% yield.
plexes were: (a) Tris-homoleptic structures [(slightly dis-
torted) D symmetries], which would permit the existence
3
of 8 or 14 positive charges per molecule. (b) Diameters
ranging from approximately 2 to 4.5 nm. (c) Flexible
bonds, which allow a certain amount of motion of the
complexes’ substituents with respect to each other. This
requirement is especially important for the use of these ru-
thenium(II) complexes as mycobacterial channel block-
of ers. (d) The synthesis should start from Ru(qpy)32 . (e)
Finally, the synthesis of the substituents themselves
+
Next
we
optimized
of
the
synthesis
tris(4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine-N¢,N¢¢)ruthenium(II)
dichloride [Ru(qpy) ]Cl (3) (Scheme 6). As we intended should be possible in a straightforward manner. The dia-
3
2
to add rather large and positively charged groups by quat- meters of the target complexes, obtained from the MM2
2
ernization of the sp nitrogens of the pyridine moieties in calculation and optimization, are summarized in Table 1.
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine, the optimization of the
w-Bromo-N-(1-methylpyridinium-4-yl)alkanamide io-
dides 9–12 were synthesized by a one-pot method
2+
synthesis of Ru(qpy) was the next logical step.
3
Refluxing 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine (1) and the (Scheme 7). The reaction of w-bromoalkanoic acids (C1–
mixture of ruthenium(II) complexes commonly abbreviat- C4) with 4-aminopyridine in dimethyl sulfoxide at 60 °C
3
2
ed as [Ru(DMSO) ]Cl for 14 hours gave 3 in only 33% using the well-established N,N¢-dicyclohexylcarbodi-
4
2
1
,26
33,34
yield after workup and subsequent recrystallization.
imide/N-hydroxysuccinimide system
yielded w-bro-
Our procedure follows the synthesis by Dürr and Thiery mo-N-(pyridin-4-yl)alkanamides 5–8, which were
closely, but avoids the filtration of the reaction mixture. methylated employing iodomethane in situ. This one-pot
Instead, the solvent is removed under high vacuum and reaction led to the desired products 9–12, which were used
the inevitable bis-complex [Ru(qpy) ]Cl 3 is removed by to assemble our highly charged (14+) target ruthenium(II)
2
2
filtration using Sephadex G25 as the stationary phase. complexes.
These minor changes resulted in a remarkable increase in
Ruthenium(II)–tris(4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine)
yield, typically, 85 ±5% have been obtained.
complexes [Ru(QP-R) ]Cl and [Ru(QP-R) ]Cl were
3
8
3
14
Naturally, we also tried to improve the yield of 3 even fur- synthesized by high-pressure synthesis, which yielded ex-
ther by employing high-pressure reaction conditions up to cellent results (Scheme 8). Reacting the w-bromoalkanoic
6
9 bar (1000 psi), but this failed. According to our find- acids (C1–C4) with [Ru(qpy) ]Cl 3 in methanol at 80 °C/
3 2
ings, heat is a far more important factor than pressure in 69 bar gave the ruthenium(II)–quaterpyridinium com-
overcoming the kinetic barrier for the formation of this plexes 13–16 in near quantitative yields. It is noteworthy
particular tris-homoleptic ruthenium(II) complex. This that there was no NMR or UV/Vis spectroscopical evi-
behavior is somewhat surprising since is not likely that dence for the occurrence of incomplete quaternization re-
significant steric hindrance would be found in this case. actions or dihalobis(quaterpyridinium)ruthenium(II)
4
+ 1,19,26
However, the formation of the tris-homoleptic complex complexes [Ru(QP-R) X ] .
2
2
N
N
N
N
N
N
Ru2+
N
N
N
N
Ru(DMSO)4Cl2
N
N
+
2 Cl–
3
N
N
HO
OH
N
N
1
3
Scheme 6 Synthesis of tris(4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine-N¢,N¢¢)ruthenium(II) dichloride [Ru(qpy) ]Cl
3
2
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

5
08
A. Shi et al.
PAPER
Table 1 Target Ruthenium(II)–Tris(quaterpyridinium) Complexes from MM2 Calculations
R
R
+
N+
N
R =
Me
4
N
N
O
O
+
+
Ru2+
(H2C)n
R
N
N
N
N
R
OH
13–16
N
N
(H2C)n
+
N
N
H
+N
N +
R
R
1
7–20
Compound
Complex, sum formula
n
–
R
–
Diameter (nm)
3
Ru(qpy)32+
1.82
2.11
2.43
2.92
2.99
3.18
3.76
3.89
4.09
4.55
C H Cl N Ru
6
0
42
2
12
4
Ru(QP-Me)38+
–
1
2
3
4
1
2
3
4
Me
C H Cl N Ru
6
6
60
8
12
1
1
1
1
1
1
1
2
3
4
5
6
7
8
9
0
Ru(QP-C1)38+
CH CO H
2
2
C H Cl N O Ru
7
2
60
8
12 12
Ru(QP-C2)38+
(CH ) CO H
2 2 2
C H Cl N O Ru
7
8
72
8
12 12
Ru(QP-C3)38+
(CH ) CO H
2 3 2
C H Cl N O Ru
8
4
84
8
12 12
Ru(QP-C4)38+
(CH ) CO H
2 4 2
C H Cl N O Ru
9
0
96
8
12 12
1
4+
+
Ru(QP-C -py)
CH CO(4-py Me)
1
3
2
C108H102Cl N O Ru
14
24
6
1
4+
+
Ru(QP-C -py)
(CH ) CO(4-py Me)
2
3
2 2
C114H114Cl N O Ru
14
24
6
1
4+
+
Ru(QP-C -py)
(CH ) CO(4-py Me)
3
3
2 3
C120H126Cl N O Ru
14
24
6
1
4+
+
Ru(QP-C -py)
(CH ) CO(4-py Me)
4
3
2 4
C126H138Cl N O Ru
14
24
6
The synthesis of the highly charged (+14), nanometer-
sized ruthenium(II)–tris(quaterpyridinium) complexes
17–20 was carried out at room temperature under high
pressure (Scheme 9). Again, yields very close to 100%
were reached.
O
Br (H2C)n
OH
N
O
+
DCC, NHS
DMSO
Br (H2C)n
HN
N
H2N
In Table 2, the some important photophysical parameters
of the newly synthesized highly charged ruthenium(II)
complexes are summarized. The occurrence of distinct
5–8
O
3
MLCT transitions in the visible range of the UV/Vis
MeI, DMSO Br (H2C)n
+
NMe I–
spectrum can be regarded as proof of the existence of a
ligand field around the ruthenium(II) center cation, which
HN
possesses D symmetry, as it is typical for all tris-homo-
9
–12
3
1
9
leptic ruthenium(II) complexes. In agreement with the
Scheme 7 N,N¢-Dicyclohexylcarbodiimide/N-hydroxysuccinimide
mediated amide formation and in situ methylation
19
paradigms developed by Balzani and co-workers and the
literature available on ruthenium(II)–quaterpyridinium
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

PAPER
Ruthenium(II)–Quaterpyridinium Complexes
509
N
N
O
N
N
1
. Br
(H2C)n
MeOH, 69 bar, 80 °C, 12 h
OH
Ru2+
N
N
N
N
2
. Dowex 50, 1 M HCl
N
N
OH
HO
O
(
CH2)n
+N
(CH2)n
N
N
O
N +
4
O
N
N
OH
+
+
N
Ru2+
(H2C)n
N
N
N
(CH2)n
O
N
N
OH
+
8 Cl–
+
+
N
N
OH
(H2C)n
(H2C)n
OH
O
O
1
3–16
Scheme 8 High-pressure synthesis of ruthenium(II)–quaterpyridinium complexes
complexes,1–16 a distinct red shift is observed for all com- ligand and replacement of the coordination sites at ruthe-
plexes 13–20. nium(II) by two chlorides.
3
The luminescence occurring from the MLCT states is ba- (b) The second pathway consists of the loss of all six sub-
2+
3
thochromically shifted as well, compared to Ru(bpy) in stituents formerly bound to the external nitrogen atoms of
1
9
H O (l
= 613 nm ).
the ruthenium(II)–quaterpyridinium complexes, thus re-
2
max,em
2
+
generating the starting complex Ru(qpy)3 . The signal
All the tris-homoleptic ruthenium complexes were ana-
lyzed using a Bruker Esquire 3000 liquid chromatography
electrospray quadrupole ion trap instrument (Table 3) and
the compounds were fully characterized by IR and H and By applying high pressure in key synthetic steps, tris-
C NMR (Table 4). As it becomes apparent from Table 3, homoleptic ruthenium(II)–quarterpyridinium complexes
+
[
C H N Ru] (m/z = 1032.2) is strongly indicative of
60 42 12
this behavior.
1
1
3
we succeeded in the destructionless ionization and detec- possessing geometric dimensions on the nano scale have
tion of the tris-homoleptic complexes 3, 4, and 13–16. The been synthesized. Due to their size, high charges (+8 or
complexes show various amounts (0, 1, 2) of complexing +14), and luminescent properties, these compounds will
chlorines. For the higher-charged (+14) ruthenium(II) be tested for various applications in the near future.
complexes 17–20, we were unable to obtain MS signals Among other applications, they will serve as mycobacte-
corresponding to the tris-homoleptic structures. Instead, rial channel blockers and monodisperse ‘bottom-up’
we observed two characteristic signals, indicating the ex- nanostructures for protein-binding experiments. Based on
istence of two pathways during electrospray MS ioniza- the properties of ruthenium(II)–tris(dimethylquaterpyri-
tion and detection:
a) For all four complexes, masses corresponding to the
bis-heteroleptic complexes [Ru(QP-C -py) Cl ] were
dinium) octachloride 4, we expect that the new complexes
will feature suitable photoelectrochemical properties for
solar energy conversion experiments as well.
(
n
2
2
found, demonstrating the occurrence of the loss of one
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

5
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A. Shi et al.
PAPER
N
N
I–
O
1.
Br
(H2C)n
+
9–12
N
N
H
mnMeOH, 69 bar, 25 °C, 12 h
N
N
2. Dowex 50, 2 M HCl
Ru2+
+
N
N
N
N
N
N
N
NH
+
N
NH
O
O
(
CH2)n
(CH2)n
N
N
+
N +
N
4
N +
O
N
N
NH
+
+
N
Ru2+
(H2C)n
N
N
N
(CH2)n
O
N
N
NH
+
14 Cl–
+N
+N
N+
H
N
(
H2C)n
(H2C)n
+
N
NH
O
O
N+
1
7–20
Scheme 9 High-pressure synthesis of highly charged ruthenium(II)–quaterpyridinium complexes
Table 2 MLCT Typical for Tris-hololeptic Ruthenium Complex with D Structure and Emission
3
–1
–1
Compound
Absorption lmax (nm) [log e (M cm )]
Fluorescence lmax,em (nm)
P–P*
d–P*
3MLCT
3MLCT
3a
4a
247 [5.12]
254 [4.77]
257 [4.84]
258 [5.04]
248 [4.85]
257 [5.03]
248 [5.01]
253 [5.03]
250 [5.00]
252 [4.98]
307 [4.98]
319 [4.08]
323 [4.41]
316 [4.48]
309 [4.59]
306 [4.55]
317 [4.61]
311 [4.63]
315 [4.48]
314 [4.58]
474 [4.53]
487 [4.20]
491 [4.23]
490 [4.27]
479 [4.21]
481 [4.19]
490 [4.14]
492 [4.04]
490 [4.22]
491 [4.60]
638
668
662
669
663
659
664
667
661
671
1
1
1
1
1
1
1
3
4
5
6
7
8
9
0
2
a
Data are in agreement with literature values.1
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Ruthenium(II)–Quaterpyridinium Complexes
511
Table 3 MS Data of the Ruthenium(II)–Tris(quaterpyridinium) Complexes
Compound
Complex sum formula
ES-MS [identified ion]
Calcd
Found
1032.3
3
4
Ru(qpy)32+
1032.3
+
C H Cl N Ru
[C H N Ru]
6
0
42
2
12
60 42 12
Ru(QP-Me)38+
1192.4
1192.4
+
C H Cl N Ru
[C H Cl N Ru]
6
6
60
8
12
60 42 2 12
1
1
1
1
1
1
1
2
3
4
5
6
7
8
9
0
Ru(QP-C1)38+
1379.3
1379.3
+
C H Cl N O Ru
[C H ClN O Ru]
7
2
60
8
12 12
72 60 12 12
Ru(QP-C2)38+
1540.4
1540.4
+
C H Cl N O Ru
[C H Cl N O Ru]
7
8
72
8
12 12
78 72 2 12 12
Ru(QP-C3)38+
1589.5
1589.5
+
C H Cl N O Ru
[C H ClN O Ru]
8
4
84
8
12 12
84 84 12 12
Ru(QP-C4)38+
1673.6
1673.6
+
C H Cl N O Ru
[C H Cl N O Ru]
9
0
96
8
12 12
90 96 8 12 12
1
4+
Ru(QP-C -py)
1392.4
1392.4, 1032.3
1448.5, 1032.3
1505.6, 1032.3
1560.6, 1032.3
1
3
+
+
+
+
C108H102Cl N O Ru
[C H Cl N O Ru]
14
24
6
72 68 2 16 4
1
4+
Ru(QP-C -py)
1448.5
2
3
C114H114Cl N O Ru
[C H Cl N O Ru]
14
24
6
80 84 2 16 4
1
4+
Ru(QP-C -py)
1505.6
3
3
C120H126Cl N O Ru
[C H Cl N O Ru]
14
24
6
80 84 2 16 4
1
4+
Ru(QP-C -py)
1560.6
4
3
C126H138Cl N O Ru
[C H Cl N O Ru]
14
24
6
84 92 2 16 4
Table 4 Characterization of the Optimized Compounds 3, 4, and 13–20
Producta FT-IR (KBr) (cm–1)
1
H NMR (400 MHz, CDCl ) d, J (Hz)
3
13
C NMR (400 MHz, CDCl ) d (Hz)
3
3
3
3340, 2940, 2810, 2750, 9.51 (d, J = 4, 6 H), 8.857 (d, J = 6, 6 H), 8.84 (d, J = 5, 6 H), 157.31, 150.765, 146.11, 142.42, 125.35,
2
1
610, 2410, 2390, 1550, 8.08 (dd, J = 7, 12 H), 8.03 (d, J = 6, 12 H)
115, 1030
121.62
4
3
9.25 (d, J = 8, 6 H), 8.93 (d, J = 7, 6 H), 8.87 (s, J = 7, 6 H), 158.82, 150.86, 147.23, 146.43, 136.23,
.20 (d, J = 9, 12 H), 8.08 (d, J = 8, 12 H), 4.44 (s, 18 H) 125.68, 121.86, 63.42
8
1
1
1
1
3340, 2945, 2810, 2755, 10.01 (s, 6 H), 9.28 (d, J = 7, 12 H), 9.09 (d, J = 8, 6 H), 9.00 174.12, 157.37, 152.86, 149.50, 146.87,
610, 2410, 2390, 1550, (d, J = 6, 6 H), 8.25 (d, J = 7, 12 H), 8.13 (s, J = 6, 6 H), 4.04 146.36, 126.86, 126.00, 125.91, 59.49
115, 1030 (s, J = 4, 12 H)
2
1
4
5
6
3340, 2945, 2810, 2755, 9.87 (s, 6 H), 9.41 (d, J = 8, 12 H), 9.07 (d, J = 6, 6 H), 8.93 171.59,157.34,152.97,150.27,148.99,14
610, 2410, 2390, 1550, (d, J = 6, 6 H), 8.23 (d, J = 8, 12 H), 8.08 (s, J = 6, 6 H), 4.91 6.15,129.28, 126.48, 125.95, 56.43,
115, 1030 (t, J = 8, 12 H), 2.08 (t, J = 4, 12 H) 34.49
2
1
3340, 2945, 2810, 2755, 9.80 (s, 6 H), 9.28 (d, J = 6, 6 H), 9.13 (d, J = 8, 12 H), 8.70 175.22,157.27,152.65,148.22,145.61,14
610, 2410, 2390, 1550, (d, J = 7, 12 H), 8.19 (d, J = 8, 12 H), 4.25 (t, d J = 7, 12 H), 4.20, 126.25,124.54,123.56,68.29,27.44,
115, 1030 3.38 (m, J = 10, 12 H), 2.08 (t, J = 7, 12 H) 21.76
2
1
3340, 2945, 2810, 2755, 9.60 (s, J = 8, 6 H) 9.00 (s, J = 6, 6 H) 8.90 (d, J = 9, 12 H), 174.02, 154.00, 152.34, 149.86, 145.52,
2
1
610, 2410, 2390, 1550, 8.21 (d, J = 8, 12 H), 8.07 (d, J = 8, 12 H), 4.75 (t, J = 7, 12 143.34, 126.12, 125.50, 122.13, 6103,
115, 1030
H), 3.38 (m, J = 10, 12 H), 2.31 (m, J = 9, 12 H), 2.08 (t,
J = 7, 12 H)
33.31, 30.84, 21.15
1
7
3345, 2940, 2810, 2750, 9.32 (d, J = 7, 6 H), 9.06 (d, J = 6, 6 H), 8.88 (d, J = 6, 6 H), 174.02, 154.00, 152.34, 149.86, 145.52,
2
1
610, 2410, 2395, 1550, 8.43 (d, J = 5, 6 H), 8.21 (d, J = 5, 6 H), 8.10 (d, J = 5, 12 H), 143.34, 126.12, 125.50, 122.13, 61.03,
115, 1030 8.03 (d, J = 6, 12 H), 7.18 (d, J = 6, 6 H), 7.00 (d, J = 6, 6 H), 33.31, 30.84, 21.15
.80 (d, J = 4, 6 H, NH), 4.42 (s, 12 H), 3.94 (s, 18 H)
6
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

5
12
A. Shi et al.
PAPER
Table 4 Characterization of the Optimized Compounds 3, 4, and 13–20 (continued)
Producta FT-IR (KBr) (cm–1)
1
H NMR (400 MHz, CDCl ) d, J (Hz)
3
13
C NMR (400 MHz, CDCl ) d (Hz)
3
3
1
8
3345, 2940, 2810, 2750, 9.48 (s, 6 H), 9.25 (d, J = 8, 6 H), 8.87 (d, J = 8, 6 H), 8.16
180.12, 159.80, 157.60, 146.70, 143.70,
139.90, 125.55, 121.87, 109.18, 108.74,
48.78, 44.20
2
1
610, 2410, 2395, 1550, (m, J = 4, 24 H), 8.07 (m, J = 4, 24 H), 6.77 (d, J = 6, 6 H,
115, 1030 NH), 3.93 (s, 12 H), 3.85 (s, 18 H), 2.89 (s, 12 H)
1
9
3345, 2940, 2810, 2750, 9.28 (d, J = 7, 6 H), 9.04 (d, J = 6, 6 H), 8.89 (d, J = 6, 6 H), 179.82, 158.64, 155.98, 150.64, 143.23,
2
1
610, 2410, 2395, 1550, 8.41 (d, J = 7, 6 H), 8.24 (d, J = 6, 6 H), 8.11 (d, J = 6, 12 H), 139.94, 125.44, 121.75, 109.21, 109.03,
115, 1030 8.02 (d, J = 6, 12 H), 7.14 (d, J = 6, 6 H), 6.95 (d, J = 7, 6 H), 108.77, 47.90, 44.50, 34.21
6
2
.80 (d, J = 6, 6 H, NH), 3.94 (t, J = 4, 12 H), 3.84 (s, 18 H),
.86 (t, J = 4, 12 H), 2.32 (t, J = 4, 12 H)
2
0
3345, 2940, 2810, 2750, 9.50 (s, 6 H), 9.27 (d, J = 7, 6 H), 9.01 (d, J = 7, 6 H), 8.15
179.40, 159.31, 151.63, 150.20, 145.90,
135.70, 122.06, 119.18, 104.20, 108.75,
2
1
610, 2410, 2395, 1550, (m, J = 4, 24 H), 8.04 (m, J = 4, 24 H), 6.77 (d, J = 5, 6 H,
115, 1030
NH), 4.43 (s, 12 H), 3.84 (s, 18 H), 2.87 (s, 12 H), 2.71 (s, 12 58.86, 48.20, 30.30, 28.88
H), 2.06 (s, 12 H)
a
Satisfactory microanalyses obtained: C ±0.04, H ±0.03, N ±0.05.
Solvents (ACS grade) and inorganic chemicals were purchased
from Aldrich and Acros Organics. DMF was further purified by
4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-Quarterpyridine (1); Procedure B
4,4¢-Bipyridine (5.0 g, 0.032 mol) were dissolved in DMF (70 mL)
and Pd/C (0.70 g) were added to the soln. The mixture was stirred
under reflux for 48 h. The solvent was removed and the residue was
azeotropic distillation of DMF–toluene–H O (85:10:5), anhydrous
2
and amine-free DMF was collected when reaching 152 °C at the
top of a 20-cm vigreux column. All other chemicals and chromatog-
raphy materials were either purchased from Aldrich, or Acros Or-
dissolved in CHCl (50 mL), then the catalyst was filtered off. A
3
bright yellow soln was obtained. CHCl was distilled under vacu-
3
ganics and used without further purification. H O was of bidistilled
um, and the residue was recrystallized three times (acetone) to ob-
tain a bright yellow product; yield: 2.2 g (44%); mp 336 °C.
2
quality. Compound 2 was prepared by following a published proce-
dure.25 All high-pressure reactions were performed in a Parr reactor
(
50 mL volume). All vacuum distillations were performed using a
4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-Quarterpyridine (1); Procedure C
Büchi rotavap equipped with a solvent recovery system and pres-
sure control. Further instrumentation: 400 MHz NMR (Varian), FT-
IR (Nicolet 870), MS: Bruker Esquire 3000, Melting point appara-
tus (Fisher), Carlo Erba Strumentatione (CHN).
Soln I: Ph P (3.05 g, 0.0115 mol) and NiCl ·6 H O (0.70 g, 0.0029
3
2
2
mol) were dissolved in anhyd DMF (30 mL). The mixture was
stirred intensely for 30 min under N at 50 °C. A dark blue color
2
emerged. Elemental Zn (0.20 g, 0.0031 mol) was added in one por-
tion. The soln immediately became brownish and after an additional
Compounds 4, 13–20 underwent decomposition when heated above
3
0 min it became dark green.
3
50 °C without melting. Compounds 9–12 melted partially under
decomposition in the temperature interval between 140 °C and
50 °C. Compounds 1, 9–12 gave satisfactory microanalyses:
C ±0.04, H ±0.03, N ±0.05.
Soln II: 4-(2-chloropyridin-4-yl)pyridine (2, 1.11 g, 0.0058 mol)
was dissolved in anhyd DMF (10 mL) and purged with N for 20
min.
1
2
Soln II was added dropwise to soln I over 10 min. The reaction tem-
perature increased to 60 °C and was then kept at that temperature
for 3 h. A dark brownish color indicated the end of the reductive
coupling reaction. The mixture was cooled to r.t. and aq 35% NH3
4
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-Quarterpyridine (1); Procedure A
,4¢-Bipyridine (10.7 g, 0.0685 mol) was dissolved in anhyd THF (3
L) under a N atmosphere. The soln was cooled to –58 °C (CO /
EtOH bath). Then, freshly prepared LDA soln [i-Pr NH (15.0 g,
0
2
2
2
(
100 mL) was added. The aqueous soln was then extracted with
.148 mol), anhyd Et O (250 mL) and 1.6 M BuLi in hexane (86
2
CH Cl (10 × 20 mL). CH Cl was removed under normal pressure
2
2
2
2
mL, 0.138 mol) under N ] was added dropwise. The mixture was
2
and then DMF under high vacuum. After DMF was completely re-
kept at –58 °C during the whole addition process, which took ap-
prox. 30 min. The mixture was then allowed to warm up to r.t. It de-
veloped a slight red color. After stirring for 30 min at r.t., the slight
N overpressure was removed and the mixture refluxed allowing
contact with air through the reflux condenser. A color change to
deep purple was observed. After 3 h of reflux, the soln was allowed
moved, Ph P was separated using column chromatography (silica
3
gel, CH Cl , R = 0.96). The product was obtained by increasing the
2
2
f
polarity of the mobile phase (CH Cl –MeOH, 95:5, R = 0.32);
2
2
f
2
yield: 0.71 g (79%).
Tris(4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridine-N¢,N¢¢)ruthenium(II)
Dichloride (3)
to cool down to r.t. H O (200 mL) was added and the organic phase
was separated and collected; the aqueous soln was extracted with
2
RuCl (0.20 g, 0.0010 mol) was dissolved in DMSO (10 mL) and
3
CH Cl (5 × 50 mL). The combined organic phases were dried
2
2
refluxed under argon until the color of the soln turned to yellow. Af-
ter cooling to r.t., ethylene glycol (30 mL) and 4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-
quarterpyridine (1, 1.2 g, 0.038 mol) were added. The mixture was
refluxed under argon for 12 h. A dark red soln was obtained. The
solvent was removed under high vacuum during 24 h. The dark red
residue was dissolved in hot water (50 mL) and then allowed to cool
to r.t. The soln was extracted CH Cl (3 × 50 mL). The aqueous
(Na SO ). After removal of the solvents under vacuum, a red oily
2 4
residue was obtained. The product was purified by column chroma-
tography (neutral alumina, CH H –MeOH, 97:3; R = 0.35). The
product was further purified by recrystallization (acetone) to give a
bright yellow solid; yield: 1.5 g (14%); mp 336 °C.
2
2
f
–
1
FT-IR (KBr): 3050, 1570, 1520, 800 cm .
2
2
1
3
phases were collected and the solvent was removed. The dark phas-
es were dissolved in EtOH–H O (90:10) and then purified by col-
H NMR (400 MHz, CDCl ): d = 8.88 (dd, J = 1 Hz, 2 H,), 8.77 (m,
J = 1 Hz, 4 H), 8.73 (dd, J = 1.4 Hz, 2 H), 7.92 (dd, J = 2.8 Hz, 4
3
3
3
3
2
3
umn chromatography (Sephadex G25). The complex was collected
as bright red fraction, whereas the formed byproducts remaining on
the column were clearly discernible by their violet colors. EtOH–
H), 7.83 (dd, J = 2.4 Hz, 2 H).
1
3
C NMR (400 MHz, CDCl ): d = 150.74, 150.64, 122.11, 121.50,
3
1
21.38, 118.11.
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

PAPER
Ruthenium(II)–Quaterpyridinium Complexes
513
H O was removed under vacuum and the complex was refluxed in
2
cal procedure gave a crude dark brown product that was recrystal-
acetone (30 mL) for 1 h and then filtered while still hot. After drying
under high vacuum for 24 h, red crystals were obtained and dried to
give a red product; yield: 0.96 g (85%).
lized twice (EtOH, ~15 mL) to give 12; yield: 0.35 g (87%).
1
H NMR (400 MHz, CDCl ): d = 8.11 (dd, J = 4 Hz, 2 H), 8.03 (d,
3
J = 4 Hz, 2 H), 6.81 (d, J = 6 Hz, 1 H), 3.85 (s, 2 H), 3.37 (s, 3 H),
2
.59 (m, 2 H), 2.31 (m, 2 H), 1.68 (m, 2 H).
Tris(N,N¢¢¢-dimethyl-4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridin-N,N¢¢¢-di-
ium-N¢,N¢¢)ruthenium(II) Octachloride [Ru(QP-Me) ]Cl (4)
1
3
C NMR (400 MHz, CDCl ): d = 173.01, 168.01, 146.95, 107.60,
3
3
8
4
8.02, 35.15, 33.02, 31.70, 24.11.
Ru(qpy) Cl (3, 0.11 g, 0.1 mmol) was dissolved in DMF (50 mL)
3
2
at r.t. and MeI (0.50 mL) was added to the soln. The mixture was
Tris[N,N¢¢¢-bis(carboxymethyl)-4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyri-
din-N,N¢¢¢-diium-N¢,N¢¢]ruthenium(II) Octachloride [Ru(QP-
C ) ]Cl (13); Typical Procedure
then stirred under N (69 bar) at 80 °C for 24 h. It was then allowed
2
to cool to r.t., the solvent was removed under vacuum and the dark
red residue was washed with acetone (3 × 20 mL). The product
1 3
8
A mixture of complex 3 (0.11 g, 0.1 mmol) and 2-bromoacetic acid
[
Ru(QP-Me) ]Cl I was dried under vacuum; yield: 0.18 g (92%).
3 2 6
(
0.20 g, 0.0014 mol) in MeOH (50 mL) was stirred under N (69
2
The complex was dissolved in hot H O (20 mL) and adsorbed on a
2
bar) at 80 °C for 12 h. The mixture was allowed to cool to r.t. and
the solvent was removed under vacuum. The dark red residue was
washed with acetone (3 × 20 mL) and dried under high vacuum to
give [Ru(QP-C ) ]Br Cl ; yield: 0.19 g (97%).
chromatography column [Dowex-50, 15 g, preconditioned with aq
1
M HCl (20 mL) and flushed with H O (40 mL)]. [Ru(QP-Me) ]Cl
2
3
8
was obtained using 1 M HCl as mobile phase. The H O–HCl was
2
1
3
6
2
removed under high vacuum to give the product 4 as red crystals;
yield: 0.13 g (99%).
The ion exchange (bromide for chloride) was achieved by using
Dowex-50 as ion exchanger, as described in the procedure for 4.
Also here, the yield was very close to quantitative (99%).
2
-Bromo-N-(1-methylpyridinium-4-yl)acetamide Iodide (9);
Typical Procedure
A mixture of 2-bromoacetic acid (0.14 g, 0.001 mol), DCC (0.23 g,
Tris[N,N¢¢¢-bis(2-carboxyethyl)-4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyri-
din-N,N¢¢¢-diium-N¢,N¢¢]ruthenium(II) Octachloride [Ru(QP-
0
.0012 mol), and NHS (catalytic amount) in DMSO (10 mL) was
C ) ]Cl (14)
stirred at 60 °C for 2 h, the soln turned to yellow. After cooling to
r.t., a white precipitate (DCU) was filtered off and a yellow soln was
obtained, to which 4-aminopyridine (0.10 g, 0.001 mol) was added
at once. The soln was stirred at 80 °C for 6 h and its color turned
dark brown. This soln, which contained 5 in 95% yield by H NMR
was directly reacted with MeI (0.30 mL). The mixture was stirred at
2 3
8
Following the typical procedure for 13, using 3-bromopropionic
acid (0.22 g, 0.0014 mol) and washing the dark red residue with ac-
etone (3 × 20 mL), gave [Ru(QP-C ) ]Br Cl ; yield 0.21 g (98.5%),
2
3
6
2
1
which was converted into 14 as given in the typical procedure in al-
most quantitative yield.
8
0 °C for 2 h and the solvent was removed under high vacuum to
Tris[N,N¢¢¢-bis(3-carboxypropyl)-4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyri-
din-N,N¢¢¢-diium-N¢,N¢¢]ruthenium(II) Octachloride [Ru(QP-
C ) ]Cl (15)
give a crude dark brown product. This was recrystallized twice
(MeOH, ca. 10 mL) to give 9; yield: 0.29 g (82%).
1
3 3
8
H NMR (400 MHz, CDCl ): d = 8.11 (dd, J = 4 Hz, 2 H), 8.03 (d,
3
Following the typical procedure for 13, using 4-bromobutanoic acid
0.24 g, 0.0014 mol) and washing the dark red residue with acetone–
J = 4 Hz, 2 H), 6.81 (d, J = 6 Hz, 1 H), 3.85 (m, 2 H), 3.36 (s, 3 H).
(
1
3
C NMR (400 MHz, CDCl ): d = 168.23, 168.02, 146.94, 107.65,
MeOH (90:10, 3 × 20 mL) gave [Ru(QP-C ) ]Br Cl ; yield: 0.21 g
3
3 3
6
2
4
8.04, 28.41.
(97.5%) which was converted into 15 as given in the typical proce-
dure in almost quantitative yield.
3
-Bromo-N-(1-methylpyridinium-4-yl)propanamide Iodide
(
10)
Tris[N,N¢¢¢-bis(4-carboxybutyl)-4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyri-
din-N,N¢¢¢-diium-N¢,N¢¢]ruthenium(II) Octachloride [Ru(QP-
C ) ]Cl (16)
Following the typical procedure for 9, a soln of 6 was obtained in
1
9
2% yield ( H NMR). Direct reaction with MeI following the typi-
4
3
8
cal procedure gave a crude dark brown product that was recrystal-
lized twice (MeOH–EtOH, 1:1, ~10 mL) to give 10; yield: 0.27 g
Following the typical procedure for 13, using 5-bromopentanoic
acid (0.26 g, 0.0014 mol) in MeOH (50 mL) and washing the dark
red residue with acetone–MeOH (90:10, 3 × 20 mL) gave [Ru(QP-
(
75%).
1
C ) ]Br Cl ; yield: 0.21 g (96.2%), which was converted into 16 as
4 3 6 2
H NMR (400 MHz, CDCl ): d = 8.11 (dd, J = 4 Hz, 2 H), 8.01 (d,
3
given in the typical procedure in almost quantitative yield.
J = 4 Hz, 2 H), 6.80 (d, J = 6 Hz, 1 H), 3.86 (s, 2 H), 3.34 (m, 3 H),
2
.30 (t, J = 3 Hz, 2 H).
Tris(N,N¢¢¢-bis{[(1-methylpyridinium-4-yl)carbonyl]methyl}-
4,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridin-N,N¢¢¢-diium-N¢,N¢¢}rutheni-
um(II) Tetradecachloride [Ru(QP-C -py) ]Cl (17); Typical
1
3
C NMR (400 MHz, CDCl ): d = 173.71, 168.02, 146.94, 107.63,
8.01, 37.70, 28.40.
3
4
1
3
14
Procedure
4
-Bromo-N-(1-methylpyridinium-4-yl)butanamide Iodide (11)
A mixture of complex 3 (0.11 g, 0.1 mmol) and compound 9 (0.40
g, 0.0011 mol) in MeOH (50 mL) was stirred under N (69 bar) at
Following the typical procedure for 9, a soln of 7 was obtained in
9
cal procedure gave a crude dark brown product that was recrystal-
lized twice (EtOH, ~8 mL) to give 11; yield: 0.35 g (91%).
2
1
4% yield ( H NMR). Direct reaction with MeI following the typi-
2
5 °C for 12 h. The solvent was removed under vacuum. The dark
red residue was washed with hot acetone (3 × 20 mL) and dried un-
der high vacuum to give [Ru(QP-C -py) ]Cl Br I ; yield: 0.30 g
(93%). Anion exchange was performed as described in the proce-
dure for 4 giving 17 in almost quantitative yield using 2 M HCl as
mobile phase.
1
3
2
6 6
1
H NMR (400 MHz, CDCl ): d = 8.11 (dd, J = 4 Hz, 2 H), 8.01 (d,
3
J = 4 Hz, 2 H), 6.80 (d, J = 6 Hz, 1 H), 3.86 (s, 2 H), 3.15 (m, 3 H),
2
.59 (t, J = 3 Hz, 2 H), 2.32 (m, 2 H).
1
3
C NMR (400 MHz, CDCl ): d = 173.01, 168.01, 146.95, 107.60,
3
Tris(N,N¢¢¢-bis{2-[(1-methylpyridinium-4-yl)carbonyl]ethyl}-
4
8.03, 34.50, 32.72, 28.51.
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridin-N,N¢¢¢-diium-N¢,N¢¢}rutheni-
um(II) Tetradecachloride [Ru(QP-C -py) ]Cl (18)
2
3
14
5
-Bromo-N-(1-methylpyridinium-4-yl)pentanamide Iodide (12)
Following the typical procedure for 17, using 10 (0.42 g, 0.0011
Following the typical procedure for 9, a soln of 8 was obtained in
8
mol), gave [Ru(QP-C -py) ]Cl Br I ; yield: 0.31 g (93%), which
1
2
3
2
6 6
3% yield ( H NMR). Direct reaction with MeI following the typi-
Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York

5
14
A. Shi et al.
PAPER
was converted into 18 as given in the typical procedure in almost
quantitative yield.
(11) Loiseau, F.; Passalacqua, R.; Campagna, S.; Polson, M. I. J.;
Fang, Y.-Q.; Hanan, G. S. Photochem. Photobiol. Sci. 2002,
1, 982.
Tris(N,N¢¢¢-bis{3-[(1-methylpyridinium-4-yl)carbonyl]propyl}-
(12) Chichak, K.; Jacquemard, U.; Branda, N. R. Eur. J. Inorg.
Chem. 2002, 2, 357.
(13) Coe, B. J.; Harris, J. A.; Jones, L. A.; Brunschwig, B. S.;
Song, K. C.; Koen; Garin, J.; Orduna, J.; Coles, S. J.;
Hursthouse, M. B. J. Am. Chem. Soc. 2005, 127, 4845.
(14) de Wolf, P.; Waywell, P.; Hanson, M.; Heath, S. L.; Meijer,
A. J. H. M.; Teat, S. J.; Thomas, J. A. Chem. Eur. J. 2006,
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridin-N,N¢¢¢-diium-N¢,N¢¢}rutheni-
um(II) Tetradecachloride [Ru(QP-C -py) ]Cl (19)
3
3
14
Following the typical procedure for 17, using 11 (0.43 g, 0.0011
mol), gave [Ru(QP-C -py) ]Cl Br I ; yield: 0.31 g (91%), which
3
3
2
6 6
was converted into 19 as given in the typical procedure in almost
quantitative yield.
12, 2188.
Tris(N,N¢¢¢-bis{4-[(1-methylpyridinium-4-yl)carbonyl]butyl}-
(15) Forster, R. J.; Keyes, T. E.; Majda, M. J. Phys. Chem. B
2000, 104, 4425.
(16) de Wolf, P.; Heath, S. L.; Thomas, J. A. Inorg. Chim. Acta
2003, 355, 280.
4
,4¢:2¢,2¢¢:4¢¢,4¢¢¢-quarterpyridin-N,N¢¢¢-diium-N¢,N¢¢}rutheni-
um(II) Tetradecachloride [Ru(QP-C -py) ]Cl (20)
4
3
14
Following the typical procedure for 17, using 12 (0.44 g, 0.0011
mol), gave [Ru(QP-C -py) ]Cl Br I ; yield: 0.32 g (94%), which
was converted into 19 as given in the typical procedure in almost
quantitative yield.
(17) Dürr, H.; Bossmann, S.; Kilburg, H.; Trierweiler, H.-P.;
Schwarz, R. In Supramolecular Sensitizers and Sensitizer/
Relay/Assemblies. A Novel Approach to Electron Transfer
Reactions; Schneider, H. J.; Dürr, H., Eds.; VCH:
Weinheim, 1991, 453–475.
4
3
2
6 6
Acknowledgment
(
18) Bossmann, S. H.; Janik, K.; Pokhrel, M. R.; Niederweis, M.
In Experimental Strategies Towards the Use of the Porin
MspA as a Nanotemplate and for Biosensors; Levy, I.;
Shoseyov, O., Eds.; The Humana Press Inc.: Totowa, NJ,
Financial support from Kansas State University, Kansas NSF-
EPSCoR (First Award #4166) and the Terry C. Johnson Center for
Basic Cancer Research (Innovative Cancer Research Grant) is
gratefully acknowledged. The authors thank Prof. Dr. John Tomich
for the use of the Bruker Esquire 3000 liquid chromatography elec-
trospray quadrupole ion trap instrument of the Biochemistry Core
Facility at KSU. The authors also thank Prof. Dr. Dan Higgins for
the use of a Fluoromax-2 fluorometer and an Agilent UV/Vis spec-
trometer.
2
007, in print.
(
(
(
19) Juris, A.; Balzani, V.; Barigelletti, F.; Campagna, S.; Belser,
P.; Von Zelewsky, A. Coord. Chem. Rev. 1988, 84, 85.
20) Faller, M.; Niederweis, M.; Schulz, G. E. Science 2004, 303,
1189.
21) Samori, P.; Francke, V.; Mangel, T.; Mullen, K.; Rabe, J. P.
Opt. Mater. 1998, 9, 390.
(
(
22) Morgan, R. J.; Baker, A. D. J. Org. Chem. 1990, 55, 1986.
23) Shorter, J. In Organic Reaction Mechanisms, 1985; Knipe,
A. C.; Watts, W. E., Eds.; John Wiley & Sons: Chichester,
1987, 299.
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Synthesis 2007, No. 4, 505–514 © Thieme Stuttgart · New York