Chiral bipyridine and terpyridine ligands grafted with L-tyrosine fragments

Article abstract of DOI:10.1055/s-2001-16766

The synthesis of stable terpyridine and bipyridine frames substituted with L-tyrosine fragments is reported. These highly functionalized compounds have been prepared from the corresponding iodo, and ethynyl substituted analogs by a reaction catalyzed by l

Full text of DOI:10.1055/s-2001-16766

PAPER
1665
Chiral Bipyridine and Terpyridine Ligands Grafted with L-Tyrosine
Fragments
C
hira
l
Bipyridine
a
b
nd
T
erpyrid
d
ine
L
igands errahim Khatyr, Raymond Ziessel*
Laboratoire de Chimie, d'Electronique et de Photonique Moléculaires, Associé au CNRS ESA-7008, Ecole de Chimie, Matériaux, Poly-
mères de Strasbourg (ECPM), 25 rue Becquerel, 67087 Strasbourg Cedex 02, France
Fax +33(3)90242689; E-mail: ziessel@chimie.u-strasbg.fr
Received 26 April 2001; revised 16 May 2001
hν'
Abstract: The synthesis of stable terpyridine and bipyridine frames
substituted with L-tyrosine fragments is reported. These highly
functionalized compounds have been prepared from the corre-
sponding iodo, and ethynyl substituted analogs by a reaction cata-
lyzed by low valent palladium(0), itself generated in situ from
palladium(II) and CuI. A tertiary amine is required to quench the na-
scent acid. Complexation of the chelating part of the molecule with
ruthenium(II) metal afforded redox and photoactive complexes.
With the terpy-Ru complex carrying a genuine tyrosine fragment an
efficient quenching reaction (kq = 2.2 109 s–1) due to electron
transfer is observed in DMF and in the presence of K2CO3. The
blank experiment performed under the same conditions with the ty-
rosine-protected benzoyl ester proved that this process is inhibited.
The synthetic methods reported herein provide a practical method-
ology to the rational design of transition metal complexes bearing
different kinds of bioactive functionalities.
Bio-
fragment
Photosensitizer
Wire
hν
Figure Schematic representation of a luminescent label with three
components: (i) a signal-generating subunit, (ii) a spacer based on wi-
res and, (iii) an anchor group from a bioactive fragment
The choice of tyrosine (TyrZ) as chiral fragment reflected
the thinking that it would act as an electron donor as re-
ported.8 In particular, in Photosystem II (PS II, a large
membrane-bounded protein complex), light energy drives
the electron transfer from water to carbon dioxide and
many cofactors including tyrosine radical intermediates
are involved. It is commonly accepted that a tetranuclear
manganese complex is associated with the PS II core and
promotes catalytic water oxidation to molecular oxygen.
During this complicate and multistep process, the primary
electron donor, a chlorophyll called P680, is excited by
light and an electron is transferred to primary electron ac-
ceptors such as pheophytin and quinones. The oxidized
Key words: bipyridine, terpyridine, palladium, alkyne, tyrosine,
electron transfer
Derivatized oligopyridine frameworks provide a versatile
platform for creating preorganized and multifunctional
ligands.1–3 This includes 2,2’:6’,2’’-terpyridine (terpy)
and 2,2'-bipyridine (bipy) chelates which have high ab-
sorptiions in the near UV based on - * transitions. A
wide range of these structurally defined -electronic and
conjugated systems have been studied and surmised to be
good candidates for electronic and optoelectronic devic-
es.4 Along these lines, we have been engaged in the syn-
thesis of preorganized ligands bearing multiple
coordination sites connected by acetylenic linkages.5
Their related complexes of RuII, OsII, ZnII, FeII provide an
unique opportunity to study vectorial energy and/or elec-
tron transfer along the main molecular axis.6 Furthermore,
by careful tailoring of the ligand it was possible to recog-
nize and detect adventitious cations.7 In continuation of
our investigations on the electronic properties of new con-
jugated systems, we have now designed a hybrid system
in which an alkyne substituted chromophore (luminescent
label) is connected to a biomolecule (tyrosine fragment)
with the goal of creating luminescent biological labels
able to be intercalated in oligonucleotides (Figure).
+
P680 retrieves an electron from the TyrZ residue which
then forms a neutral radical as shown in the equation be-
low. Similar radicals are involved in enzymes, e.g. Galac-
tose Oxidase9 and a plethora of model systems have
appeared past in the literature.10 Mimicking electron
transfer reactions of naturally occurring proteins and en-
zymes has attracted a lot of attention.11
+
TyrZ + P680
Tyrz + P680 + H+
Combination of chromophoric ruthenium fragments con-
nected to tyrosine subunits via efficient electronic conduit
such as acetylenic junction is a promising starting point
for the further development of advanced models for the
water-oxidizing complex in PS II, as well as to perfect ar-
tificial water oxidation catalysts. We wish to describe
herein novel molecules bearing a chelating fragment (bpy
or terpy) connected via an ethynyl sp-bridge to an optical-
ly pure tyrosyl moiety.
The starting material used in this protocol is the esterified
analog to 3-iodo-L-tyrosine which was prepared in meth-
anol in the presence of an excess thionyl chloride as
shown in Scheme 1.
Synthesis 2001, No. 11, 28 08 2001. Article Identifier:
1437-210X,E;2001,0,11,1665,1670,ftx,en;Z04501SS.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881
During this first step, the chloride salt 2 is formed from 1
in excellent yield.12 It was soon established that the trans-
formation of 2 to the corresponding amide required spe-

1666
A. Khatyr, R. Ziessel
PAPER
OH
OH
I
I
(i)
COOCH3
COOH
H3N
Cl
H2N
H
H
2
1
O
(ii)
(iii)
OH
NH
O
I
I
O
COOCH3
O
COOCH3
H
NH
H
3
4
(v)
(iv)
(iv)
N
N
N
O
N
N
N
OH
O
OH
N
N
O
O
COOCH3
O
COOCH3
COOCH3
NH
NH
H
NH
H
H
7
6
5
Scheme 1 (i) SOCl2, MeOH, 70 °C, 92%; (ii) benzoyl chloride (2 equiv), Et3N (6 equiv) 45 °C, 73%; (iii) benzoyl chloride (1 equiv), Et3N
(2 equiv), 45 °C, 92%; (iv) 4'-terpyOTf, Pd(PPh3)2Cl2 (6 mol%), CuI (6 mol%), THF, i-Pr2NH, r.t., 49% for 7 and 42% for 5; (v) 5-ethynyl-
2,2'-bipyridine, Pd(PPh3)2Cl2 (6 mol%), CuI (6 mol%), THF, i-Pr2NH, r.t., 57%
cial reaction conditions and the formation of the amide/ have been made in the amidation of the amine function of
ester species 3 was prone to low yield in the presence of L-tyrosine.12
an excess benzoyl chloride and triethylamine (Table 1).
The molecules bearing a chelating fragment (bipy or
Compound 4 bearing two esters and one amide functions terpy) connected via an ethynyl sp-bridge to the optically
is obtained with an isolated yield of 73% in the presence pure L-tyrosyl moiety were constructed by cross-coupling
of two equivalents of benzoyl chloride and six equivalents the mono-protected compound 3 with either 5-ethynyl-
of base. The optimal conditions for the preparation of 3 2,2’-bipyridine13 or 4’-ethynyl-2,2’:6’,2’’-terpyridine5
(89% isolated yield) requires one equivalent of benzoyl (Scheme 1). The diprotected compound 4 was also pre-
chloride and two equivalents of base. All intermediate sit- pared in good yield applying the same protocol and will
uations provide a mixture of both compounds (Table 1). serve as an important test complex in subsequent photo-
Compounds 3 ([ ]D +11) and 4 ([ ]D +17) compared to the induced electron transfer studies. The low valent palladi-
starting material 2 ([ ]D –6) generate a positive Cotton ef- um(0) required for these cross-coupling reactions was
fect which is responsible for the signal inversion and an generated in-situ from Pd(PPh3)2Cl2 and CuI in the pres-
increase of the rotatory power. Analogous observations ence of a large excess of i-Pr2NH which quenched the na-
scent acid.14
Complexation of the terpy-based ligands 5 and 7 was in-
sured by reaction with [Ru(terpy)(S)3]2+ (S = DMSO or
Table 1 Selected Experimental Data Concerning the Synthesis of
Compounds 3 and 4a
methanol) obtained by silver dehalogenation of
Ru(terpy)(DMSO)Cl215 in methanol. Complexation of the
2 (mol C6H5COCl Et3N
Reaction
Time (h)
Isolated Yield
(%) of 3 and 4
bipy fragment in 6 is straightforward and was carried out
by reaction with Ru(bipy)2Cl2·2H2O16 in ethanol
(Scheme 2). The three ruthenium(II) complexes 8–10 dis-
play well defined - * absorption bands due to the bipy or
terpy moieties in the UV part of the absorption spectra and
intense metal-to-ligand-charge-transfer (MLCT) absorp-
tion bands with maxima at 492 nm and 452 nm respective-
ly for the terpy and bipy complexes. Furthermore all
complexes are reversibly oxidized to ruthenium(III)
around 1.27 V versus the saturated calomel reference
equiv)
(mol
(mol
equiv)
equiv)
1
1
1
1
1
4
4
2
6
4.5
6
31 (3), 22 (4)
12 (3), 45 (4)
89 (3)
1.5
1
20
8
2
73 (4)
a In CH2Cl2 at r.t.
Synthesis 2001, No. 11, 1665–1670 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Chiral Bipyridine and Terpyridine Ligands
2 +
1667
N
OR
N
OR
N
(i), (ii)
N
N
N
Ru
-
2 PF6
O
O
N
N
COOCH3
N
COOCH3
NH
NH
H
H
8
R = H
R = COPh
5
R = H
R = COPh
9
7
2 +
N
N
N
N
Ru
OH
OH
-
2 PF6
N
N
N
(iii)
N
O
O
COOCH3
H
COOCH3
NH
NH
H
6
10
Scheme 2 (i) AgBF4 (2 equiv.), Ru(terpy)(DMSO)Cl2, MeOH, 80 °C; (ii) MeOH, 80 °C, 69% for 8 and 58% for 9; (iii) Ru(bipy)2Cl2 2H2O,
EtOH, 80 °C, 58%
electrode, while successive and reversible reduction of the the electroactive domain (until +1.50 V).17 It is presumed
terpy’s occurred at ca –1.20 V and ca –1.54 V and at – that this oxidation is kinetically inhibited under the used
1.20, –1.50 and –1.72 V for the 'Ru(bipy)3' complex 10. experimental conditions.
No apparent oxidation of the phenol group is found within
Scheme 3 Schematic representation of: (a) the photoinduced electron transfer in compound 8 under basic conditions; (b) the photoexcitation
of compound 9 under similar conditions, light is emitted during the relaxation process
Synthesis 2001, No. 11, 1665–1670 ISSN 0039-7881 © Thieme Stuttgart · New York

1668
A. Khatyr, R. Ziessel
PAPER
Table 2 Selected Spectroscopic and Redox Data for the Ruthenium(II) Complexesa
Compound
abs (nm)
T (ns)
E
Ox (V)
ERed (V)
em
Lum
(10–3)
( M–1cm–1)
(nm)
[Ru(terpy)2]2+
474 (15300)
492 (28800)
492 (24400)
450 (14600)
454 (10900)
650
660
660
627
635
0.6
112
<0.1
2.8
2.5
62
1.27 (1e–)
1.25 (1e–)
1.27 (1e–)
1.30 (1e–)
1.29 (1e–)
–1.27 (1e–), –1.51 (1e–)
–1.19 (1e–), –1.54 (1e–)
–1.20 (1e–), –1.51 (1e–)
8
9
110
[Ru(bipy)3]2+
980
–1.25 (1e–), –1.52 (1e–), –1.79 (1e–)
–1.20 (1e–), –1.50 (1e–), –1.72 (1e–)
10
1100
70
a In argon degassed acetonitrile, abs for the metal-ligand-charge-transfer absorption band, em for the emission maximum, T for the triplet
lifetime, Lum for the emission quantum yield, EOx for the oxidation potential, ERed for the sucessive reduction potentials quoted versus the sat-
urated calomel electrode using ferrocene as internal reference E0 Fc/Fc+ = +0.39 V. The number of exchanged electrons is given in parentheses
and tetrabutylammonium hexafluorophosphate is used as supporting electrolyte.
Preliminary photophysical results showed that these new
r.t., Et2O (20 mL) was added, the resultant precipitate collected by
complexes are highly emissive in solution and at room
temperature, with triplet excited state lifetimes about 180
times longer for complexes 8 and 9 compared to
[Ru(terpy)2]2+. As expected a weaker effect is observed
for complex 10 when compared to [Ru(bipy)3]2+. Selected
data are gathered in Table 2. Interestingly, in the presence
of K2CO3 in DMF at room temperature, the lifetime of
complex 8 drops dramatically short ( = 0.37 ns), indicat-
ing that the triplet excited state is quenched by electron
transfer with a estimated rate of 2.2 109 s–1 (Scheme 3).
Back electron transfer to regenerate the ground state is
certainly fast due to a large driving force and prevents the
observation of the tyrosine radical by transcient absorp-
tion spectroscopy. Hence related complex 9 in which the
phenolate is not available due to the protection with the
benzoyl fragment, the quenching process is not observed.
Work is in progress in order to have a deeper insight into
this interesting conjugated system.
filtration, washed with Et2O (2 10 mL) and dried under high vac-
uum; yield: 1.08 g (92%); mp 211–212 °C; [ ]D – 6 (c = 5 g/L in
CH2Cl2).
1H NMR (D2O + t-BuOH): = 3.22 (m, CH2, 2 H), 3.89 (s, OCH3,
3
3
3 H), 4.40 (t, JH-H = 6.8 Hz, CH, 1 H), 6.98 (d, JH-H = 8.4 Hz, 1
Harom), 7.20 (dd, 3JH-H = 8.4 Hz, 4JH-H = 2.2 Hz, 1 Harom), 7.72 (d, 4JH-
H = 2.2 Hz, 1 Harom).
13C{1H} NMR (D2O + t-BuOH): = 31.1, 50.4, 50.9, 80.8, 112.4,
124.4, 127.7, 136.9, 151.8, 166.8.
FT-IR (KBr): = 3274 (s), 2991 (s), 2951 (s), 2879 (s), 2699 (m),
1742 (s), 1603 (m), 1579 (m), 1505 (s), 1444 (m), 1416 (s), 1347
(m), 1284 (s), 1248 (s), 1217 (s), 1141 (m), 821 cm–1 (m).
UV-Vis (H2O): max ( , M–1 cm–1) = 283 nm (2,300).
MS (FAB+): m/z (nature of peak, relative intensity) = 322 ([M –
Cl]+, 100).
Anal. Calcd for C10H13ClINO3 (357.6): C, 33.59; H, 3.66; N, 3.92.
Found: C, 33.23; H, 3.44; N, 3.65.
N-Benzoyl-3-Iodo-L-tyrosine Methyl Ester (3)
In summary, we have developed a practical method for the
synthesis of L-tyrosine-substituted terpyridines and bipy-
ridine, which avoid the drawbacks proned by more con-
ventional methods. It is worth noting that Sonogashira
To a suspension of 2 (0.20 g, 0.56 mmol) in CH2Cl2 (20 mL) was
added Et3N (0.156 mL, 1.12 mmol). After dissolution (0.5 h), ben-
zoyl chloride (0.065 mL, 0.56 mmol) was added and the mixture
was stirred at r.t. for 20 h. Purification was performed by chroma-
coupling reaction tolerate the presence of phenol, ester tography on alumina eluting with CH2Cl2–MeOH (0% to 2%). The
analytically pure white compound was obtained after recrystalliza-
tion from CH2Cl2–hexane affording 219 mg of 3 (92%); mp 123–
124 °C; [ ]D + 11 (c = 5 g/L in CH2Cl2).
and amide functions without perturbing significantly the
course of the palladium-promoted catalytic reaction. In
turn, these ligands are versatile targets for the construction
of redox and photoactive complexes. This is of particular
importance in that it represents a facile route to the prepa-
ration of chiral luminophoric fragments. The ready avail-
1H NMR (CDCl3): = 3.12 (m, CH2, 2 H), 3.76 (s, OCH3, 3 H), 5.01
(m, CH, 1 H), 5.65 (s, 1 H), 6.75 (d, 3JH-H = 7.3 Hz, 1 H), 6.84 (m,
2 H), 7.45 (m, 4 H), 7.71 (d, 3JH-H = 6.95 Hz, 2 H).
13C{1H} NMR (CDCl3): = 36.4, 52.6, 53.7, 84.9, 115.2, 127.0,
ability of the reagents, the overall simplicity of the
128.6, 129.2, 130.6, 132.0, 133.4, 139.3, 154.8, 167.4, 172.0.
procedure, the use of mild reaction conditions, and the
FT-IR (KBr): = 3425 (s), 2945 (m), 2356 (w), 1738 (s), 1641 (s),
reasonable yields obtained suggest that this methodology
1603 (w), 1575 (w), 1535 (s), 1487 (m), 1416 (m), 1290 (m), 1219
is an useful entry for the preparation of hybrid molecules
(s), 1024 (w), 714 cm-1 (m).
bearing a bioactive fragment.18,19
UV-Vis (CH2Cl2): max ( , M–1 cm–1) = 281 (2,800), 289 nm (2,500).
MS (FAB+): m/z (nature of peak, relative intensity) = 426 ([M + H]+,
100), 367 ([M – CO2CH3 + H]+, 30).
3-Iodo-L-tyrosine Methyl Ester Hydrochloride (2)
To a stirred solution of 1 (1g, 3.26 mmol) in anhyd MeOH (25 mL)
at 0 °C was added dropwise SOCl2 (3 mL, 41.13 mmol) over 0.5 h
and the mixture was heated for 3 h at 70 °C. After cooling down to
Anal. Calcd for C17H16INO4 (425.2): C, 48.02; H, 3.79; N, 3.29.
Found: C, 47.89; H, 3.57; N, 2.99.
Synthesis 2001, No. 11, 1665–1670 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Chiral Bipyridine and Terpyridine Ligands
1669
N,O-Dibenzoyl-3-Iodo-L-tyrosine Methyl Ester (4)
This compound was prepared by following the procedure described
above for 3 using 2 (200 mg, 0.56 mmol) in CH2Cl2 (40 mL), Et3N
(0.468 mL, 3.356 mmol) and benzoyl chloride (0.064 mL, 0.56
mmol). The mixture was stirred at r.t. for 8 h. Purification was per-
formed by chromatography on alumina eluting with CH2Cl2 to af-
ford 216 mg of 4 (73%); mp 203–204 °C; [ ]D +17 (5 g/L in
CH2Cl2).
1H NMR (CDCl3): = 3.28 (m, CH2, 2 H), 3.81 (s, OCH3, 3 H), 5.11
(m, CH, 1 H), 6.71 (d, 3JH-H = 6.9 Hz, 1 H), 7.20 (m, 2 H), 7.52 (m,
5 H), 7.69 (m, 4 H), 8.26 (m, 2 H).
na with CH2Cl2–MeOH (0% to 3%) as eluent to afford 58 mg of 6
(57%); mp 218–219 °C; [ ]D + 37 (c = 5 g/L in CH2Cl2).
1H NMR (CDCl3): = 3.38 (m, CH2, 2 H), 3.79 (s, OCH3, 3 H), 5.12
(m, CH, 1 H), 6.61 (d, 3JH-H = 7.3 Hz, 1 H), 7.08 (m, 3 H), 7.47 (m,
4 H), 7.80 (m, 4 H), 8.22 (dd, 3JH-H = 8.5 Hz, 4JH-H = 2.2 Hz, 1 H),
8.47 (td, 3JH-H = 8.5 Hz, 4JH-H = 2.2 Hz, 2 H), 8.71 (d, 3JH-H = 8.4 Hz,
1 H), 9.15 (m, 1 H).
FT-IR (KBr): = 3280 (s), 3047 (s), 2947 (s), 2915 (s), 2365 (w),
1748 (s), 1649 (s), 1579 (m), 1536 (s), 1459 (m), 1434 (m), 1260
(m), 1230 (s), 1009 (m), 795 cm–1 (m).
UV-Vis (MeCN): max ( , M–1 cm–1) = 336 nm (22,700).
13C{1H} NMR (CDCl3): = 36.8, 52.6, 53.5, 90.4, 123.0, 127.0,
128.6, 128.7, 129.0, 130.3, 130.4, 131.9, 133.7, 133.9, 135.7, 140.2,
150.5, 164.2, 167.0, 171.7.
MS (FAB+): m/z (nature of peak, relative intensity) = 478 ([M + H]+,
100), 419 ([M – CO2CH3 + H]+, 50).
Anal. Calcd for C29H23N3O4 (477.5): C, 72.94; H, 4.85; N, 8.80.
Found: C, 72.62; H, 4.59; N, 8.65.
FT-IR (KBr): = 3328 (s), 2944 (m), 2362 (w), 1733 (s), 1638 (s),
1602 (w), 1578 (w), 1527 (s), 1487 (m), 1449 (m), 1373 (m), 1320
(m), 1260 (s), 1203 (s), 1160 (m), 1081 (m), 705 cm–1 (m).
UV-Vis (CH2Cl2): max ( , M–1 cm–1) = 269 nm (3,500).
Ligand 7
This ligand was prepared according to the general procedure, start-
ing from a solution of 4 (100 mg, 0.189 mmol) in THF (8 mL),
4’-ethynyl-2,2’:6’,2’’-terpyridine (58 mg, 0.227 mmol),
Pd(PPh3)2Cl2 (8 mg, 0.011 mmol), CuI (2 mg, 0.011 mmol) and di-
isopropylamine (2 mL). Purification was performed by chromatog-
raphy on alumina with CH2Cl2–MeOH (0% to 10%) as eluent to
give 61 mg of 7 (49%); mp 232–233 °C; [ ]D + 49 (c = 5 g/L in
CH2Cl2).
MS (FAB+): m/z (nature of peak, relative intensity) = 530 ([M + H]+,
100), 426 ([M – PhCO + 2 H]+, 20), 320 ([M – 2 PhCO + H]+, 5).
Anal. Calcd for C24H20INO5 (529.3): C, 54.46; H, 3.82; N, 2.65.
Found: C, 54.15; H, 3.62; N, 2.47.
Ligands 5–7; General Procedure
A Schlenk flask was charged stepwise with derivatives 3 or 4 and
4’-ethynyl-2,2’:6’,2’’terpyridine or 5-ethynyl-2,2’-bipyridine in ar-
gon degassed THF, then with Pd(PPh3)2Cl2 (6 mol%) and CuI (6
mol%) and finally argon degassed diisopropylamine was added.
The mixture was stirred for 3 d at r.t. After consumption of the start-
ing material (followed by TLC), the solvent was evaporated and the
residue was purified by chromatography on alumina using CH2Cl2
with a gradient of MeOH.
1H NMR (CDCl3): = 3.23 (m, CH2, 2 H), 3.82 (s, OCH3, 3 H), 5.11
(m, CH, 1 H), 6.64 (d, 3JH-H = 6.7 Hz, 1 H), 6.92 (d, 3JH-H = 8.3 Hz,
1 H), 7.11 (d, 3JH-H = 8.5 Hz, 1 H), 7.23 (d, 4JH-H = 2.0 Hz, 1 H), 7.41
(m, 10 H), 7.78 (dd, 3JH-H = 7.8 Hz, 4JH-H = 1.7 Hz, 2 H), 7.87 (td,
3JH-H = 7.8 Hz, 4JH-H = 1.7 Hz, 2 H), 8.53 (s, 2 H), 8.60 (d, 3JH-H
=
7.8 Hz, 2 H), 8.73 (m, 2 H).
FT-IR (KBr): = 3272 (m), 3058 (w), 2954 (m), 2923 (s), 2851 (m),
2211 (w), 1739 (s), 1637 (m), 1576 (s), 1488 (m), 1465 (s), 1391 (s),
1262 (s), 1215, (m), 1177 (m), 891 (w), 792 cm–1 (s).
Ligand 5
This ligand was prepared according to the general procedure, start-
ing from a solution of 3 (110 mg, 0.258 mmol) in THF (10 mL), 4’-
ethynyl-2,2’:6’,2’’-terpyridine (80 mg, 0.310 mmol), Pd(PPh3)2Cl2
(10 mg, 0.014 mmol), CuI (3 mg, 0.016 mmol) and diisopropy-
lamine (3 mL). Purification was performed by chromatography on
alumina with CH2Cl2–MeOH (0% to 4%) as eluent and afforded 60
mg of 5 (42%); mp 224–225 °C; [ ]D + 41 (5 g/L in CH2Cl2).
1H NMR (CDCl3): = 3.37 (m, CH2, 2 H), 3.79 (s, OCH3, 3 H), 5.12
(m, CH, 1 H), 6.72 (d, 3JH-H = 7.8 Hz, 1 H), 7.11 (d, 3JH-H = 8.4 Hz,
1 H), 7.41 (m, 8 H), 7.74 (dd, 3JH-H = 8.0 Hz, 4JH-H = 1.8 Hz, 2 H),
7.86 (td, 3JH-H = 8.0 Hz, 4JH-H = 1.8 Hz, 2 H), 8.62 (dd, 3JH-H = 8.0
Hz, 4JH-H = 0.7 Hz, 2 H), 8.73 (m, 2 H), 8.83 (m, 2 H).
UV-Vis (MeCN):
(37,400).
( , M–1 cm–1) = 288 (55,900), 311 nm
max
MS (FAB+): m/z (nature of peak, relative intensity) = 659 ([M + H]+,
100), 600 ([M – CO2CH3 + H]+, 30), 495 ([M – CO2CH3 – PhCO +
H]+, 10).
Anal. Calcd for C41H30N4O5 (658.7): C, 74.76; H, 4.59; N, 8.51.
Found: C, 74.63; H, 4.42; N, 8.39.
Ruthenium Complexes 8–10; General Procedures
Experimental Condition 1: A stirred solution of Ru(terpy)(DM-
SO)Cl2 (1 equiv) and AgBF4 (2 equiv) in argon degassed MeOH
was heated at 80 °C for 8 h. After cooling to r.t., the deep-red solu-
tion was filtered over cotton-wool and transferred via cannula to a
suspension of the terpy-ligands (1 equiv) in MeOH (3 mL) and the
solution was heated at 80 °C for 2 d. After complete consumption
of the starting material, a solution of KPF6 (5 equiv) in H2O (10 mL)
was added, the organic solvent was than removed under vacuum
and the precipitate was purified by chromatography on alumina
eluting with CH2Cl2 using a gradient of MeOH (0% to 5%). The
pure red-orange compounds were obtained by recrystallization from
CH2Cl2–hexane.
FT-IR (KBr): = 3261 (m), 3057 (m), 2951 (m), 2923 (m), 2854
(m), 1737 (s), 1644 (s), 1608 (s), 1581 (s), 1540 (s), 1466 (s), 1438
(m), 1400 (s), 1347 (w), 1262 (m), 1229 (m), 1121 cm–1 (w).
UV-Vis (MeCN):
(27,900).
( , M–1 cm–1) = 286 (28,200), 317 nm
max
MS (FAB+): m/z (nature of peak, relative intensity) = 555 ([M + H]+,
100), 496 ([M –CO2CH3 + H]+, 20).
Anal. Calcd for C34H26N4O4 (554.6): C, 73.63; H, 4.73; N, 10.10.
Found: C, 73.43; H, 4.42; N, 9.72.
Experimental Condition 2: A stirred solution of Ru(bpy)2Cl2 H2O
(1 equiv) in MeOH and the bipy ligand was heated at 80 °C for 16
h. The pure complex was obtained as described above for com-
pound 1.
Ligand 6
This ligand was prepared according to the general procedure, start-
ing from a solution of 3 (90 mg, 0.212 mmol) in THF (7 mL),
5-ethynyl-2,2’-bipyridine (46 mg, 0.255 mmol), Pd(PPh3)2Cl2 (9
mg, 0.012 mmol), CuI (2.3 mg, 0.012 mmol) and diisopropylamine
(1.5 mL). Purification was performed by chromatography on alumi-
Ruthenium Complex 8
Prepared according to experimental conditions 1, starting from
Ru(terpy)(DMSO)Cl2 (35 mg, 0.07 mmol), AgBF4 (28 mg, 0.14
Synthesis 2001, No. 11, 1665–1670 ISSN 0039-7881 © Thieme Stuttgart · New York

1670
A. Khatyr, R. Ziessel
PAPER
mmol), of 5 (0.040 g, 0.07 mmol) and MeOH (20 mL) to give 59 mg
of 8 (69%).
1H NMR (acetone-d6): = 3.42 (m, CH2, 2 H), 3.75 (s, OCH3, 3 H),
5.03 (m, CH, 1 H), 7.29– 7.58 (m, 8 H), 7.68– 7.90 (m, 8 H), 8.04–
8.19 (m, 6 H), 8.60 (t, 3JH–H = 8.2 Hz, 1 H), 8.83 (d, 3JH-H = 7.5 Hz,
2 H), 9.07 (m, 4 H), 9.52 (s, 2 H).
Acknowledgement
We thank the Engineer School of Chemistry (ECPM) for partial fi-
nancial support and the CNRS for continuous support. We express
our sincere appreciation to Professor Anthony Harriman for the
measurements of the optical properties of all luminescent com-
pounds.
FT-IR (KBr) 3070 (m), 2958 (w), 1738 (s), 1652 (s), 1613 (s), 1580
(m), 1541 (s), 1486 (m), 1464 (m), 1450 (s), 1431 (s), 1401 (m),
1389 (s), 1357 (m), 1287 (m), 1267 (m), 1246 (m), 1205 (m), 1135
cm–1 (w).
UV-Vis (MeCN): max ( , M–1 cm–1) = 272 (40,200), 308 (63,600),
492 nm (28,800).
References
(1) Munakata, M.; Wu, L. P.; Kuroda-Sowa, T. Adv. Inorg.
Chem. 1999, 46, 173.
(2) Ziessel, R. Synthesis 1999, 1839.
(3) Thummel, R. P.; Chamchoumis, C. M. Adv. Nitrogen
Heterocycl. 2000, 4, 107.
MS (FAB+): m/z (nature of peak, relative intensity) = 1033 ([M –
PF6]+, 16), 889 ([M – 2 PF6 + H]+, 100), 696 ([M – CH(NH-
COPh)(CO2CH3) – 2 PF6]+, 50).
(4) (a) Reed, M. A.; Zhou, C.; Muller, C. J.; Burgin, T. P.; Tour,
J. M. Science 1997, 278, 252. (b) Collier, C. P.; Wong, E.
W.; Belohradsky, M.; Raymo, F. M.; Stoddart, J. F.; Kuekes,
P. J.; Williams, R. S.; Heath, J. R. Science 1999, 285, 391.
(c) Collier, C. P.; Mattersteig, G.; Wong, E. W.; Luo, Y.;
Kristen, K.; Sampaio, J.; Raymo, F. M.; Stoddart, J. F.;
Heath, J. R. Science 2000, 289, 1172. (d) Gittins, D.;
Bethell, D.; Schiffrin, D. J.; Nichols, R. J. Nature 2000, 408,
67.
(5) Ziessel, R.; Suffert, J.; Youinou, M.-T. J. Org. Chem. 1996,
61, 6535.
(6) (a) Ziessel, R. J. Chem. Educ. 1997, 74, 673. (b) Harriman,
A.; Ziessel, R. Coord. Chem. Rev. 1998, 171, 331; and
references cited therein.
Anal. Calcd for C49H37F12N7O4P2Ru (1177.9): C, 49.92; H, 3.16; N,
8.32. Found: C, 49.74; H, 3.15; N, 8.00.
Ruthenium Complex 9
Prepared according to experimental condition 1, starting from
Ru(terpy)(DMSO)Cl2 (18 mg, 0.04 mmol), AgBF4 (15 mg, 0.08
mmol), 7 (25 mg, 0.04 mmol) and MeOH (15 mL) to give 28 mg of
9 (58%).
1H NMR (acetone-d6): = 3.43 (m, CH2, 2 H), 3.74 (s, OCH3, 3 H),
5.02 (m, CH, 1 H), 7.28– 7.56 (m, 10 H), 7.67– 7.90 (m, 10 H),
8.03– 8.22 (m, 6 H), 8.59 (t, 3JH-H = 8.1 Hz, 1 H), 8.83 (d, 3JH-H = 8.3
Hz, 2 H), 9.07 (t, 3JH-H = 8.1 Hz, 4 H), 9.53 (s, 2 H).
(7) Hissler, M.; El-ghayoury, A.; Harriman, A.; Ziessel, R.
Angew. Chem. Int. Ed. Engl. 1998, 37, 1717.
(8) Barber, J.; Andersson, B. Nature 1994, 370, 31; and
references cited therein.
(9) Whittaker, J. W. In Metal Ions in Biological Systems, Vol.
30; Sigel H., Sigel A. Marcel Dekker: New York, 1994, 315–
360.
(10) (a) Marko, I. E.; Giles, P. R.; Tsukazaki, M.; Brown, S. M.;
Urch, C. J. Nature 1996, 274, 2044. (b) Chaudhuri, P.;
Hess, M.; Flörke, U.; Wieghardt, K. Angew. Chem. Int. Ed.
Engl. 1998, 37, 2217. (c) Chaudhuri, P.; Hess, M.;
Weyhermüller, T.; Wieghardt, K. Angew. Chem. Int. Ed.
1999, 38, 1095.
(11) Magnuson, A.; Berglund, H.; Korall, P.; Hammarström, L.;
Akermark, B.; Styring, S.; Sun, L. J. Am. Chem. Soc. 1997,
119, 10720.
FT-IR (KBr): = 2955 (m), 2924 (s), 2854 (m), 1738 (s), 1652 (m),
1601 (s), 1579 (m), 1533 (s), 1484 (m), 1449 (s), 1385 (s), 1287 (m),
1266 (m), 1247 (s), 1196 (m), 1020 (w), 842 cm–1 (s).
UV-Vis (MeCN): max ( , M–1 cm–1) = 272 (39,000), 308 (57,200),
492 nm (24,400).
MS (FAB+): m/z (nature of peak, relative intensity) = 1138 ([M –
PF6]+, 100), 1079 ([M – CO2CH3 – PF6]+, 60), 993 ([M – 2PF6]+,
10), 974 ([M – CO2CH3 – PhCO – PF6]+, 30).
Anal. Calcd for C56H41F12N7P2O5Ru CH3CN (1324.1): C, 52.61; H,
3.35; N, 8.46. Found: C, 52.74; H, 3.49; N, 8.63.
Ruthenium Complex 10
Prepared according to experimental conditions 2, starting from
Ru(bpy)2Cl2 2H2O (22 mg (0.04 mmol)), 6 (20 mg, 0.04 mmol) and
MeOH (20 mL), to give 26 mg of 10 (58%).
1H NMR (acetone-d6): = 3.34 (m, CH2, 2 H), 3.69 (s, OCH3, 3 H),
4.95 (m, CH, 1 H), 7.38– 7.95 (m, 14 H), 8.07– 8.39 (m, 12 H), 8.58
(t, 3JH-H = 7.5 Hz, 1 H), 8.84 (m, 6 H).
(12) Jung, M. E.; Rohloff, J. C. J. Org. Chem. 1985, 50, 4909.
(13) Grosshenny, V.; Romero, F. M.; Ziessel, R. J. Org. Chem.
1997, 62, 1491.
(14) Sonogashira, K. In Comprehensive Organic Synthesis, Vol.
3; Trost B. M., Fleming L., Paquette L. A. Pergamon Press:
Oxford, 1990, 545–547.
FT-IR (KBr): = 2951 (w), 1741 (s), 1648 (s), 1602 (s), 1529 (m),
1444 (s), 1441 (s), 1245 (m), 1216 (m), 1035 (w), 843 cm–1 (s).
UV-Vis (MeCN): max ( , M–1 cm–1) = 286 (64,000), 333 (22,200),
365 (33,000), 454 nm (10,900).
MS (FAB+): m/z (nature of peak, relative intensity) = 1035 ([M –
PF6 – H]+, 35), 930 ([M – PhCO – PF6]+, 100), 890 ([M – 2PF6 –
H]+, 14), 831 ([M – CO2CH3 – 2PF6 – H]+, 6).
(15) Grosshenny, V.; Ziessel, R. J. Organomet. Chem. 1993, 453,
C19.
(16) Sprintschnik, G.; Sprintschnik, H. W.; Kirsch, P. P.;
Whitten, D. J. Am. Chem. Soc. 1977, 99, 4847.
(17) Harriman, A. J. Phys. Chem. 1987, 91, 6104.
(18) Khatyr, A.; Ziessel, R. Org. Lett. 2001, 3, 1857.
(19) Mayer, A.; Neuenhofer, S. Angew. Chem. Int. Ed. Engl.
1994, 33, 1044.
Anal. Calcd for C49H39N7O4RuP2F12 (1180.9): C, 49.84; H, 3.33; N,
8.30. Found: C, 49.71; H, 3.12; N, 8.19.
Synthesis 2001, No. 11, 1665–1670 ISSN 0039-7881 © Thieme Stuttgart · New York