Synthesis of soluble bis-terpyridine ligands bearing ethynylene- phenylene spacers

Article abstract of DOI:10.1021/jo9919355

Soluble and rigid terpyridine-based ditopic ligands bearing one to five phenylene/ethynylene modules have been synthesized by way of a stepwise procedure. Each module is attached to the terpyridine unit via an ethynylene fragment and functionalized at the

Full text of DOI:10.1021/jo9919355

3126
J . Org. Chem. 2000, 65, 3126-3134
Syn th esis of Solu ble Bis-ter p yr id in e Liga n d s Bea r in g
Eth yn ylen e-P h en ylen e Sp a cer s
Abderrahim Khatyr and Raymond Ziessel*
Laboratoire de Chimie, d’Electronique et de Photonique Mole´culaires, Associe´ au CNRS ESA-7008,
Ecole de Chimie, Mate´riaux, Polyme`res de Strasbourg (ECPM), 25 rue Becquerel,
67087 Strasbourg Cedex 02, France
Received December 17, 1999
Soluble and rigid terpyridine-based ditopic ligands bearing one to five phenylene/ethynylene modules
have been synthesized by way of a stepwise procedure. Each module is attached to the terpyridine
unit via an ethynylene fragment and functionalized at the 4-position with an additional ethynylene
connector and in the 2,5-positions with two flexible dodecyloxy chains. The synthetic protocol is
based on sequential Pd(0)-catalyzed cross-coupling reactions between a terpyridine subunit grafted
with the necessary diethynyl/phenyl or ethynylphenyl/bromide appendage. For ditopic ligands
displaying an even number of phenyl/ethynylene modules, the final step involves a single cross-
coupling reaction between 4′-ethynylene-2,2′:6′,6′′-terpyridine and the appropriate bromo derivative.
In the case of the ligands having an odd number of phenylene/ethynylene fragments, a double
cross-coupling reaction between an extended dibromopolyphenylene intermediate and 4′-ethynylene-
2,2′:6′,6′′-terpyridine or 1-(4′-ethynylene-2,2′:6′,2′′-terpyridine)-4-ethynylene-2,5-didodecyloxy-
benzene is required. For ligands I-V, optimal preparative conditions were found with [Pd0(PPh3)4]
(6 mol %) in n-propylamine at 70 °C. Oxidative dimerization of the 1-(4′-ethynylene-2,2′:6′,2′′-
terpyridine)-4-ethynylene-2,5-didodecyloxybenzene derivative in the presence of cupric salts and
oxygen gives the corresponding homoditopic ligand II2 bearing a central diphenyldiacetylene spacer.
Spectroscopic data for the new oligomers are discussed in terms of the extent of π-electron
conjugation. Upon increasing the number of phenylene/ethynylene modules, there is a progressive
lowering in energy of absorption and fluorescence transitions.
In tr od u ction
polyenes,13,14 polyalkynes,15-19 polyphenylenes,20-22 poly-
phenyl/alkyne,23,24 or polythiophenes25,26 units.
The design of multicomponent molecules of precise
length and shape has attracted much interest due to their
potential use as building blocks for construction of
nanoarchitectures, such as molecular wires or molecular-
scale electronic devices.1,2 An important, but as yet
unresolved, issue concerns how best to interlock the
various components (chromophores, conductor, electronic
relays...) into ordered arrays that allow controlled trans-
fer of stored information along the molecular axis.
Particularly attractive are molecular-based systems where
photoinduced energy- or electron-transfer processes can
be realized over large distances and in preferred direc-
tions.3 Earlier work has shown that the nature of the
spacer separating photoactive terminals plays a crucial
role in the efficiency and mechanism of information
transfer. Various types of connecting bridge have been
explored, including cyanides,4 DNA,5,6 polypeptides,7,8
aliphatic chains,9-11 p-phenylenevinylene oligomers,12
In particular, we note that extremely fast electron
exchange has been observed to take place along poly-
alkynylene bridges, with the rate of transfer being almost
insensitive to the length of the connector.27 Recent results
have also shown that the electronic conductivity of
polyalkynes can be modulated by inserting aromatic units
into the carbon chain.28 These various experiments infer
that preorganized modules bearing central acetylene
(11) Klan, P.; Wagner, P. J . J . Am. Chem. Soc. 1998, 120, 2198.
(12) Davis, W. B.; Svec, W. A.; Ratner, M. A., Wasielewski, M. R.
Nature 1998, 396, 60.
(13) Effenberger, F.; Wolf, H. C. New J . Chem. 1991, 15, 117.
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D. F. J . Am. Chem. Soc. 1996, 118, 3996.
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40, 72.
(17) Tzalis, D.; Tor, Y. Chem. Commun. 1996, 1043. Tzalis, D.; Tor,
Y. J . Am. Chem. Soc. 1997, 119, 852. Connors, P. J ., J r.; Tzalis, D.;
Dunnick, A. L.; Tor, Y. Inorg. Chem. 1998, 37, 1121.
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J . 1997, 3, 1105.
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Zanello, P.; Fabrizi de Biani, F. Eur. J . Inorg. Chem. 1999, 1.
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Coudret, C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L.
Chem. Rev. 1994, 94, 993.
(1) Harriman, A.; Ziessel, R. Chem. Commun. 1996, 1707.
(2) Seminario, J . M.; Tour, J . M. In Molecular Electronics-Science
and Technology; Aviran, A., Ratner, M., Eds.; New York Academy of
Science, New York, 1998; p 69.
(3) Balzani, V.; Scandola, F. Supramolecular Chemistry: Concepts
and Perspectives; Horwood: Chichester, UK, 1991.
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Chem. Soc. 1990, 112, 7099 and references therein.
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J . Am. Chem. Soc. 1999, 121, 4207.
(5) Dandliker, P. J .; Holmlin, R. E.; Barton, J . K. Science 1997, 275,
1465. Kelley, S. O.; J ackson, N. M.; Hill, M. G.; Barton, J . K. Angew.
Chem., Int. Ed. 1999, 38, 941 and references therein.
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62, 1388. Huang, S.; Tour, J . M. Tetrahedron Lett. 1999, 40, 3347.
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(10) Paddon-Row: M. N. Acc. Chem. Res. 1994, 27, 18.
10.1021/jo9919355 CCC: $19.00 © 2000 American Chemical Society
Published on Web 04/22/2000

Synthesis of Soluble Bis-terpyridine Ligands
J . Org. Chem., Vol. 65, No. 10, 2000 3127
Sch em e 1a
a
Key: (i) CCl4, Br2 (4 equiv), 80 °C, 10 h, 97%; (ii) HCtC(CH3)2OH (2 equiv), nPrNH2, [Pd0(PPh3)4] (6 mol %), 60 °C, 20 h, 86%; (iii)
NaOH (excess), toluene, 100 °C, 24 h; 81%; (iv) NaOH (excess), benzene, 70 °C, 22 h, 69%.
bonds might be suitable for building macroscopic elec-
tronic devices. The realization that pulsed illumination
provides a rapid and easy way to trigger such devices
has ensured study of many different chromophores, such
as porphyrinic arrays,29-31 polypyridine complexes,32 and
numerous organic molecules.33 More recently, attention
has focused on oligopyridines that are readily function-
alized with alkyne groups under mild conditions and in
good yield.34 Despite the synthetic versatility and diver-
sity of these ligands, there are important drawbacks
associated with the use of alkynylated polycyclic aromatic
hydrocarbons. In particular, the solubility of the resultant
ligands decreases significantly as more acetylene groups
are added, thereby hindering construction of molecules
of nanometric dimension.35
A plausible way to extend the molecular length of such
wires without introducing undue solubility problems is
to make use of 1,4-disubstituted phenylene fragments
bearing solubilizing groups in the 2,5-positions.22,36,37 We
now present a detailed description of the preparation of
back-to-back terpyridine-based ligands of nanometric
dimension which are suitable for the chelation of lumi-
nophoric metal centers. The synthesis of these rationally
designed ditopic ligands requires an iterative strategy
based on palladium-promoted cross-coupling reactions to
extend the central spacer framework outward from the
1,4-diethynylene-2,5-didodecyloxybenzene core. This study
complements an earlier preliminary report of the syn-
thesis of these ligands.37
Resu lts a n d Discu ssion
A synthetic strategy was developed for the synthesis
of a set of linear terpyridine-based ditopic ligands retain-
ing identical chelating functions but of varying molecular
length. The adopted procedure utilizes key intermediates
1-8, each of which is readily prepared by palladium-
mediated coupling chemistry.38,39 Precursor 1 is synthe-
sized by reaction of the corresponding dibromo derivative
with propargylic alcohol (Scheme 1). Complete deprotec-
tion, performed in refluxing toluene under basic condi-
tions, affords the bis-terminal alkyne 2 in good yield.
Selective monodeprotection, giving access to 3 in 81%
yield, was achieved by refluxing in benzene under basic
conditions for relatively short reaction times. Owing to
the poor solubility of the mineral base in aromatic
solvents, it is surmised that these deprotection reactions
are essentially heterogeneous. Cross-coupling of 2 with
1,4-dibromo-2,5-(didodecyloxy)benzene forms the pivotal
intermediate 4 (Scheme 2) in modest yield. The limited
efficiency of this reaction is attributed to the presence of
two reactive aryl bromide functions, which lead to
competitive polymerization steps. In developing this
procedure, a set of general conditions has been identified,
and the main points are gathered in Table 1. The isolated
yield of 4 increases significantly with (i) increasing
(28) Hissler, M.; El-ghayoury, A.; Harriman, A.; Ziessel, R. Angew.
Chem., Int. Ed. 1998, 37, 1717.
(29) Osuka, A.; Maruyama, K.; Mataga, N.; Asahi, T.; Yamazaki,
I.; Tamai, N. J . Am. Chem. Soc. 1990, 112, 4958.
(30) Li, F.; Yang, S. Ik.; Ciringh, Y.; Seth, J .; Martin, C. H.; Singh,
D. L.; Kim, D.; Birge, R. R.; Bocian, D. F.; Holten, D.; Lindsey, J . S. J .
Am. Chem. Soc. 1998, 120, 10001.
(31) Harriman, A.; Hissler, M.; Trompette, O.; Ziessel, R. J . Am.
Chem. Soc. 1999, 121, 2516.
(32) Ziessel, R. J . Chem. Educ. 1997, 74, 673 and references therein.
(33) Kumar, C. V.; Tolossa, L. M. J . Phtochem. Photobiol. A: Chem.
1994, 78, 63. Zeng, H.-H.; Wang, K.-M.; Li, D.; Yu, R.-Q. Talanta 1994,
41, 969. Mohr, G. J .; Lehmann, F.; Grummt, U.-W.; Spichiger-Keller,
U. E. Anal. Chem. Acta 1997, 344, 215 and references therein.
(34) Ziessel, R.; Suffert, J .; Youinou, M.-T. J . Org. Chem. 1996, 61,
6535.
(35) Grosshenny, V.; Romero, F. M.; Ziessel, R. J . Org. Chem. 1997,
62, 1491.
(36) Huang, S.; Tour, J . M. J . Am. Chem. Soc. 1999, 121, 4908.
(37) Khatyr, A.; Ziessel, R. Tetrahedron Lett. 1999, 40, 5515.
(38) Heck, R. F. Org. React. 1981, 27, 345.
(39) Weijin, T.; Nesbitt, S.; Heck, R. F. J . Org. Chem. 1990, 55, 63.

3128 J . Org. Chem., Vol. 65, No. 10, 2000
Khatyr and Ziessel
Sch em e 2a
a
Key: (i) nPrNH2, [Pd0(PPh3)4] (6 mol %), 70 °C, 48 h, 81%.
Sch em e 3a
a
i
Key: (i) PrNH, benzene, [Pd0(PPh3)4] (6 mol %), 60 °C, 40 h, 70%; (ii) NaOH (excess), benzene, 80 °C, 36 h, 70%; (iii) 1,4-dibromo-
2,5-(dodecyloxy)benzene, nPrNH2, [Pd0(PPh3)4] (6 mol %), 70 °C, 4 days, 62%.
Ta ble 1. P a lla d iu m -Ca ta lyzed Syn th esis of Dibr om o
Der iva tive 4a
Similarly, reaction of 6 with the extended dibromo
derivative 4 favors preparation of intermediate 8 in 47%
yield (Scheme 4), while inescapable cross-coupling be-
tween 8 and 6 affords ligand V as a side-product (15%).
The importance of a careful choice of the experimental
conditions for controlling the iterative divergent/conver-
gent synthetic approach of similar adducts, possessing
dual potentiality to undergo further reactivity, has been
observed previously.40
ratio of equivalent
dibromo
cmpd/derivative 2
volume of
reaction
time (days)
isolated
yields (%)
nPrNH2 (mL)
2.4
2.4
2.5
3.0
3.0
3.0
30
20
15
15
15
10
3
3
3
2
3
3
14
31
50
81
73
68
In fact, the rigid ditopic ligands were readily prepared
by a Pd(0)-promoted reaction using the appropriate
precursors by way of a single cross-coupling step for the
ligands bearing an even number of phenylene/ethynylene
modules and through a double cross-coupling step for
ligand build with an odd number of modules. Thus, ligand
I was obtained by reacting 2 equiv of terpy-OTf with the
diethynylene-derivative 2, whereas ligand II1 was pre-
pared under stoichiometric conditions from intermediate
7 and 4′-ethynylene-2,2′:6′,6′′-terpyridine (Scheme 5).
Furthermore, ligand III was synthesized by the reaction
of 2 equiv of 4′-ethynylene-2,2′:6′,6′′-terpyridine with the
extended dibromo derivative 4 while ligand IV was
obtained under similar experimental conditions from
intermediate 7 and 4′-ethynylene-2,2′:6′,6′′-terpyridine
(Scheme 6). Finally, V was obtained from 2 equiv of
intermediate 6 and the dibromo derivative 4. Application
a
At 70 °C using 6 mol % in palladium.
concentration of reactants and (ii) increasing ratio of
dibromo versus diethynylene derivative. In this latter
case, shorter reaction times are possible and the optimal
yield reaches about 80%.
Access to the family of rigid ligands bearing an even
number of phenylene/ethynylene modules requires the
terpyridine-based precursors 6, 7, and 8. The key species
6 was prepared in 49% overall yield by a cross-coupling
reaction between 3 and 4′-[[(trifluoromethyl)sulfonyl]-
oxy]-2,2′:6′,2′′-terpyridine (terpy-OTf) in the presence of
catalytic amounts of a palladium(0) complex, followed by
deprotection under basic conditions. Further reaction of
6 with 1,4-dibromo-2,5-(dodecyloxy)benzene under simi-
lar conditions affords intermediate 7 in 62% yield (Scheme
3). Here, the side product assigned as ligand III (16%)
results from parasitic cross-coupling between 7 and
residual 6. Despite varying the experimental conditions,
this side reaction could not been prevented entirely.
(40) Ley, K. D.; Li, Y.; J ohnson, J . V.; Powell, D. H.; Schanze, K. S.
Chem. Commun. 1999, 1749.

Synthesis of Soluble Bis-terpyridine Ligands
J . Org. Chem., Vol. 65, No. 10, 2000 3129
Sch em e 4a
a
Key: (i) nPrNH2, [Pd0(PPh3)4] (6 mol %), 70 °C, 4 days, 47%.
Sch em e 5a
a
i
Key: (i) Pr2NH, benzene, [Pd0(PPh3)4] (6 mol %), 60 °C, 3 days, 80%; (ii) nPrNH2, [Pd0(PPh3)4] (6 mol %), 60 °C, 3 days, 70%; (iii)
CuCl (0.5 equiv), TMEDA (0.5 equiv), acetonitrile, O2, rt, 5 days, 74%.

3130 J . Org. Chem., Vol. 65, No. 10, 2000
Khatyr and Ziessel
Sch em e 6a
a
Key: (i) nPrNH2, [Pd0(PPh3)4] (6 mol %), 70 °C, 2-5 days, 55% for III, 27% for IV, 57% for V.
of these coupling reactions is straightforward and gives
the required ditopic ligand in acceptable yield (Scheme
6).
framework. Nonetheless, the 13C NMR spectra are more
useful with respect to identification of the final struc-
tures. The region between δ ) 93 and 90.5 ppm, being
typical of acetylenic signals, clearly points to the number
of triple bonds. Upon systematically increasing the
number of ethynylene/phenylene modules there is the
expected increase in the number of ethynylene carbon
signals. There is no significant shielding [with the
exception of ligand II2] of these peaks, as previously
observed with diethynyleneated or triethynyleneated
compounds.34 As might be expected, the sp-hybridized C
atoms tend to give signals lying at very similar chemical
shifts as the chain grows longer but the expected number
of signals is always reflected in the spectrum. The FT-
IR spectra remain similar throughout the series, with the
most pronounced bands occurring at ν ≈ 3000, 1650-
1100, and between 850 and 620 cm-1. The spectrum is
dominated by vibrations associated with the aromatic
rings, but the acetylene stretching vibration, although
rather weak, can be resolved and at about 2200 cm-1 in
each case.
An important question relating to these ditopic ligands
concerns the extent of electronic communication along
the molecular axis. In part, this point can be addressed
using UV-visible absorption spectroscopy, and the main
findings are collected in Figures 1 and 2. It is seen that
the lowest energy absorption transition is shifted pro-
gressively toward lower energy as the number of repeat
units increases. Thus, ligand 5 with a total of 78
conjugated π-electron units exhibits the most pronounced
red-shift absorption maximum (Figure 1). The shift of λ
Oxidative homocoupling of monosubstituted ethyn-
ylene derivatives with cupric salts in oxygenated solu-
tions is usually efficacious.41 In the case of compound 6,
oxidative dimerization with CuCl proceeded smoothly to
give the desired product in excellent yield. This reaction
is best performed in the presence of a bidentate ligand,
such as N,N,N′,N′-tetramethylethylenediamine, and oxy-
gen at room temperature.42 The final product, ligand II2,
carries a central butadiyne diphenyl spacer subunit
(Scheme 5).
The pure ligands and intermediates are soluble in most
chlorinated solvents and are isolated as pale-yellow to
deep-yellow powders. Characterization has been made by
NMR, mass spectrometry, UV-vis spectroscopy, and FT-
IR and elemental analysis. All data are consistent with
the assigned structures, and in particular, the observed
carbon and proton chemical shifts and vibrational stretch-
ing frequencies are in good agreement with those re-
ported for other ethynylated derivatives.35,43,44 The 1H
NMR spectrum recorded for each ligand clearly indicates
the absence of any overlap between those signals belong-
ing to the terpyridine fragments and orther aromatic
protons, thereby clarifying the nature of the molecular
(41) Eglinton, G.; McCrae, W. Adv. Org. Chem. 1963, 4, 225.
(42) Hay, A. S. J . Org. Chem. 1960, 25, 1275; 1962, 27, 3320.
(43) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N.
Synthesis 1980, 627.
(44) Austin, W. B.; Bilow, N.; Kelleghan, W. J .; Lau, K. S. Y. J . Org.
Chem. 1981, 46, 2280.
drops from an initial step of ∆λabs ) 25 ( 2 nm (I f II1or 2
)

Synthesis of Soluble Bis-terpyridine Ligands
J . Org. Chem., Vol. 65, No. 10, 2000 3131
in emission maximum tends toward a plateau for the
longer molecules (Figure 2). Thus, there is a weak
decrease of λem from ∆λem ) 16 ( 2 nm (I f II1or 2) to
∆λem ) 8 ( 2 nm (III f IV) and ∆λem ) 3 ( 2 nm (IV f
V). It is also noteworthy that the fluorescence quantum
yields are relatively high and quite insensitive to the
molecular length [φ ) 25.3% for I; φ ) 30.1% for II1; φ )
42.2% for II2; φ ) 38.5% for III; φ ) 30.1% for IV; φ )
29.2% for V, in argon-degassed dichloromethane solutions
with an excitation wavelength at 383 nm for I and at
402 nm for the orther ligands]. The highest value is found
for ligand II2, which has the highest oscillator strength
for the corresponding absorption transition. In fact, the
ratio of molar extinction coefficients measured for ligand
II2 and II1 (75 800 versus 58 300 M-1cm-1) reflects the
relative fluorescence yields. More importantly, the fluo-
rescence spectrum shows poor mirror symmetry with the
lowest energy absorption transition, and in fact, the
absorption and fluorescence spectra look quite different.
This is also partially confirmed by excitation spectra
carried out under similar experimental conditions.
Whereas the fluorescence band can safely be attribute
to a π,π* state, it follows that the absorption transition
is not due to the same state. Either the absorption
transition is belonging to a higher lying π,π* state or to
a state of different character, e.g., a CT state. Either way,
the lowest energy singlet state S0 f S1 (the one seen in
fluorescence) must be hidden beneath the more intense
S0 f S2 band.46
F igu r e 1. UV-vis absorption spectra measured in dichloro-
methane (2 × 10-5 M) at room temperature for various ligands
I-V.
The limiting effect observed on the decrease in λ shifts
for the increasing number of phenyl/ethynyl modules may
be inferred to the fact that the number of conjugated
units might be limited to the first phenylene/acetylene
moieties, whereas vibration of the molecular framework
and rotation about the sp-sp2 linkage drastically reduce
delocalization. Alternatively, it is to be expected that
charge is mainly localized at each adjoining unit, and the
small but significant effects observed with increasing
number of n are a result of minor disturbances which
perturb the localized system. It is anticipated that
complexation of each terpyridine to a transition metal
will be a possible way of increasing electronic delocal-
ization by indirect lowering of the LUMO-orbital in these
oligomeric frameworks.28,47
In summary, we have presented a logical synthetic
protocol for the synthesis of soluble back-to-back ter-
pyridine-based ditopic ligands. At each stage of the
procedure, key intermediates were prepared by either a
selective or a complete deprotection reaction. One set of
reaction conditions based on Pd(O)-catalyzed Sonogashira
cross-coupling reactions48 is suitable for the entire itera-
tive synthetic sequence. For each phenylene/ethynylene
increment a small bathochromic shift in absorption and
emission maxima is observed. This effect is attenuated
by increasing the length of the spacer. All ligands exhibit
a high fluorescence quantum yield when excited in the
less energetic absorption band. The ready availability of
the reagents, the overall simplicity of the procedure, the
use of mild reaction conditions, and the resonable yields
obtained suggest that this methodology will be useful for
F igu r e 2. Normalized fluorescence emission spectra mea-
sured in degassed dichloromethane (ca. 1.2 10-6 M) at room
temperature for various ligands I-V (excitation wavelength
at 383 nm for I and 402 nm for the other ligands). Emission
wavelengths are as follows: 434 nm for I; 451 nm for II1; 450
nm for II2; 461 nm for III; 469 nm for IV; 472 nm for V.
to ∆λabs ) 13 ( 2 nm (II1 f II2) and to ∆λabs ) 9 ( 2 nm
(IV f V). Ligand I shows a pronounced long-wavelength
absorption tail that is not obvious for the other com-
pounds. This tail might be due to overlap of π-orbitals of
the phenylene and acetylene units that is hidden by more
intense absorption bands for the other compounds. The
presence of a triplet excited state is excluded by the fact
that no change in the steady-state emission was observed
when the emission spectra of I were carried out with an
oxygen-degassed solution in dichloromethane at room
temperature.45 The broad and structureless absorption
bands exhibited by these linear ditopic ligands are
reminescent of charge-transfer (CT) transitions, and it
is noteworthy that the compounds contain an electron
donor (i.e., the 2,5-dialkoxybenzene unit) and an electron
acceptor (i.e., the terminal terpyridine unit). The appar-
ent Stokes’ shift (range of 51 to 39 nm) is too large for a
π,π* state but quite normal for a CT state.
The ditopic ligands fluoresce quite strongly in dichlo-
romethane solution, with the peak of the fluorescence
band shifting toward lower energy with increasing num-
ber of repeat units in the bridge. Again, the relative shift
(46) Birks, J . B. In Photophysics of Aromatic Molecules; Wiley-
Interscience: New York, 1970.
(47) Ziessel, R. J . Incl. Phenom. Macro. Chem. 1999, 35, 369.
(48) Sonogashira, K. In Comprehensive Organic Synthesis; Trost,
B. M., Fleming, L., Paquette, L. A., Eds.; Pergamon Press: Oxford,
1990; Vol. 3, pp 545-547.
(45) Kaiwar, S. P.; Vodacek, A.; Blough, N. V.; Pilato, R. S. J . Am.
Chem. Soc. 1997, 119, 3311. Pilato, R. S.; Van Houten, K. A. In
Multimetalliv and Macromolecular Inorganic Photochemistry; Rama-
murthy, V., Schanze, K. S., Eds.; Marcel Dekker: New York, 1999;
Vol. 4, pp 185-214.

3132 J . Org. Chem., Vol. 65, No. 10, 2000
Khatyr and Ziessel
Con d ition 4a . To a stirred solution of the protected ethynyl
derivative in benzene was added excess NaOH, and the
mixture was heated at 70 °C. When the monodeprotected
derivative was the major product (determined by TLC), the
reaction was quenched with water and a saturated solution
of NH4Cl. The product was extracted with dichloromethane,
and the organic layers were dried over MgSO4. The solvent
was then evaporated and the compound purified by flash
chromatography on silica gel, eluting with dichloromethane
with a gradient of methanol.
the preparation of other polytopic ligands. The chemical
and photostability of these rigid-rod conjugated oligomers
make them very attractive for the construction of lumi-
nophoric d-block metal complexes where they could act
as molecular wires.
Exp er im en ta l Section
Gen er a l Meth od s. The 200.1 (1H) and 50.3 MHz (13C) NMR
spectra were recorded at room temperature, unless otherwise
specified, using perdeuterated solvent as internal standard:
δ (H) in ppm relative to residual protiated solvent in CDCl3
(7.26); δ (C) in ppm relative to the solvent in CDCl3 (77.0), all
carbon signals were detected as singlets. Melting points were
obtained on a Bu¨chi 535 capillary melting point apparatus in
open-ended capillaries and are uncorrected. FT-IR spectra
measured in KBr pellets. UV-vis spectra were measured in
CH2Cl2 at room temperature. Luminescence experiments were
performed in dilute (ca. 1.2 10-6 M) dichloromethane solutions
at room temperature. Luminescence maxima reported are
uncorrected for photomultiplier response. Luminescence quan-
tum yields were measured following the optical dilution
method,49 with [Ru(bpy)3]2+ in degassed acetonitrile with as
the standard with a quantum yield of φ ) 0.016.50 Fast-atom
bombardement (FAB, positive mode) mass spectra were ob-
tained using m-nitrobenzyl alcohol (m-NBA) as matrix.
Ma ter ia ls. n-Propylamine and 2-methyl-3-butyn-2-ol were
purchased from ACROS; CuCl was purchased from Aldrich
Chemical Co.; N,N,N′,N′-tetramethylethylenediamine (TME-
DA) was purchased from Fluka; 1,4-dibromo-2,5-(dodecyloxy)-
benzene,51 4′-[[(trifuoromethyl)sulfonyl]oxy]-2,2′:6′,6′′-terpyri-
dine,52 and 4′-ethynyl-2,2′:6′,6′′-terpyridine,53 [Pd0(PPh3)4]54
were prepared and purified according to literature procedures.
Diisopropylamine and acetonitrile were dried over suitable
reagents and freshly distilled under argon before use. All
reactions were carried out under dry argon by using Schlenk
tube techniques.
Gen er a l P r oced u r e for th e P r ep a r a tion of th e Ar yl-
acetylen es an d P olytopic Ligan ds. Con dition 1. A Schlenk
flask equipped with a septum, a Teflon-coated magnetic
stirring bar, and an argon inlet was charged with the bromo
and ethynyl derivatives in argon-degassed n-propylamine, and
finally [Pd0(PPh3)4] (6 mol %) was added as a solid. After
heating at 60-70 °C and complete consumption of the starting
material (determined by TLC), the solvent was evaporated,
and the residue was purified by chromatography on alumina
for terpyridine derivatives or silica gel for the benzene deriva-
tives, using dichloromethane with a gradient of methanol or
ethyl acetate as the mobile phase.
Con d ition 2. A Schlenk flask was charged with the triflate
and ethynyl derivatives in argon-degassed benzene, then [Pd0-
(PPh3)4] (6 mol %) was added as a solid and followed by argon-
degassed diisopropylamine. The yellow solution was heated
at 70 °C. After complete consumption of the starting material,
the solvent was evaporated and the product was purified by
chromatography on alumina eluting with dichloromethane.
Con d ition 3. To a deep-green oxygen-degassed solution of
CuCl and N,N,N′,N′-tetramethylethylenediamine (TMEDA) in
acetonitrile, the ethynyl derivative was added and the solution
stirred at room temperature. During the course of the reaction,
periodic oxygenation of the solution, with a gentle flow of pure
molecular oxygen, was carried out, and a white precipitate was
formed. After 5 days, an aqueous solution (5 mL) of KCN (0.1
mmol) was added and the solvent was evaporated. The residue
was extracted with dichloromethane (3 × 50 mL), and the
product was purified by chromatography on alumina with
dichloromethane as the mobile phase.
Con d ition 4b. Similar to 4a but using refluxing toluene.
Syn th esis of Liga n d P r ecu r sor s. 1,4-(2-Meth yl-3-bu t-
yn -2-ol)-2,5-d id od ecyloxyben zen e (1). The compound was
prepared according to experimental conditions 1, from 0.250
g (0.41 mmol) of 1,4-dibromo-2,5-(dodecyloxy)benzene, 20 mL
of n-propylamine, 0.080 mL (0.83 mmol) of 2-methyl-3-butyn-
2-ol, and 0.029 g (0,02 mmol) of [Pd(PPh3)4]. The reaction
mixture was heated during 20 h at 60 °C. Purification was
performed by flash chromatography on silica gel with CH2Cl2/
CH3OH (0 to 10%) as eluant and afforded 0.218 g of 1 (86%):
mp 93-4 °C; 1H NMR (CDCl3) δ 0.88 (t, J ) 6.4 Hz, CH3, 6H),
1.27 (m, CH2, 36H), 1.62 (s, CH3, 12H), 1.78 (m, CH2, 4H), 2.10
(s, OH, 2H), 3.93 (t, J ) 6.4 Hz, OCH2, 4H), 6.85 (s, Ph, 2H);
13C NMR (CDCl3) δ 14.1, 22.7, 26.0, 29.3, 29.4, 29.6, 31.4, 31.9,
65.6, 69.4, (78.4, 99.1, CtC), 113.3, 116.9, 153.5; FT-IR (KBr,
cm-1) 2921 (s), 2853 (s), (2227 (w, CtC), 1400 (s), 1220 (s);
UV-vis (CH2Cl2): λ nm (ꢀ, M-1 cm-1) 246 (1600), 281 (10 600),
335 (11 000); FAB+ m/z (nature of the peak, relative intensity)
611 ([M + H]+, 100), 551 ([M - C(CH3)2OH]+, 20). Anal. Calcd
for C40H66O4: C, 78.64; H, 10.89. Found: C, 78.52; H, 10.69.
1,4-Dieth yn yl-2,5-d id od ecyloxyben zen e (2). The com-
pound was prepared according to experimental conditions 4b,
from 1 0.100 g (0.16 mmol), 1 g of NaOH (excess), and 20 mL
of toluene. The reaction mixture was heated during 24 h at
100 °C. Purification was performed by flash chromatography
on silica gel with CH2Cl2 as eluant and afforded 0.066 g of 2
1
(81%): mp 81-2 °C; H NMR (CDCl3) δ 0.88 (t, J ) 6.4 Hz,
CH3, 6H), 1.27 (m, CH2, 36H), 1.80 (m, CH2, 4H), 3.33 (s, Ct
CH, 2H), 3.97 (t, J ) 6.6 Hz, OCH2, 4H), 6.95 (s, Ph, 2H); 13
C
NMR (CDCl3) δ 14.1, 22.7, 25.9, 29.1, 29.4, 29.6, 31.4, 31.9,
69.6, (79.8, 82.4, CtC), 113.2, 117.7, 153.9; FT-IR (KBr, cm-1
)
3282 (s), 2921 (s), 2847 (s), (2107 (w, CtC), 1957 (w), 1501
(s), 1465 (s), 1384 (s), 1211 (s), 1112 (m), 1030 (s); UV-vis (CH2-
Cl2) λ nm (ꢀ, M-1 cm-1) 233 (20 900), 262 (14 800), 271 (23 500),
337 (6800); FAB+ m/z (nature of the peak, relative intensity)
495 ([M + H]+, 100), 309 ([M - OC12H25]+, 15). Anal. Calcd
for C34H52O2: C, 82.53; H, 11.00. Found: C, 82.53; H, 10.67.
1-(2-Meth yl-3-bu tyn -2-ol)-4-eth yn yl-2,5-d id od ecyloxy-
ben zen e (3). The compound was prepared according to
experimental conditions 4a, from 1 0.100 g (0.16 mmol), 1 g of
NaOH (excess), and 20 mL of benzene. The mixture was heated
during 22 h at 70 °C. Purification was preformed by flash
chromatography on silica gel with CH2Cl2/MeOH (95/5) as
eluant and afforded 0.017 g of 3 (69%): mp 71-2 °C; 1H NMR
(CDCl3) δ 0.88 (t, J ) 6.2 Hz, CH3, 6H), 1.26 (m, CH2, 36H),
1.63 (s, CH3, 6H), 1.79 (m, CH2, 4H), 2.31 (s, OH, 1H), 3.31 (s,
CtCH, 1H), 3.95 (td, J ) 6.2, 12.1 Hz, OCH2, 4H), 6.87 (s,
Ph, 1H), 6.92 (s, Ph, 1H); 13C{1H} NMR (CDCl3) δ 14.1, 22.7,
25.9, 26.0, 29.1, 29.3, 29.6, 31.4, 31.9, 46.4, 57.8, 65.7, 69.5,
69.6, (78.3, 79.9, 82.1, 99.3, CtC), 112.6, 114.1, 117.1, 117.7,
153.4, 154.1; FT-IR (KBr, cm-1) 3425 (w), 3270 (s), 2923 (s),
2852 (s), 1502 (s), 1467 (m), 1391 (s), 1274 (m), 1220 (s), 1160
(m), 1020 (m), 960 (w); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1
)
242 (8500), 266 (19 600), 275 (28 100), 337 (12 600); FAB+ m/z
(nature of the peak, relative intensity) 553 ([M + H]+, 100),
493 ([M - C(CH3)2OH]+, 15). Anal. Calcd for C37H60O3: C,
80.38; H, 10.94. Found: C, 80.53; H, 10.52.
1,4-[1-Br om o-2,5-(d od ecyloxy)b en zen e)-4-ylet h yn yl]-
2,5-d id od ecyloxyben zen e (4). The compound was prepared
according to experimental conditions 1, from 0.034 g (0.068
mmol) of 1,4-diethynyl-2,5-(dodecyloxy)benzene 2, 15 mL of
n-propylamine, 0.100 g (0.165 mmol) of 1,4-dibromo-2,5-
(dodecyloxy)benzene, and 0.012 g (0.01 mmol) of [Pd(PPh3)4].
The reaction mixture was heated during 3 days at 70 °C.
Purification was performed by flash chromatography on silica
(49) Demas, J . N.; Crosby, G. A. J . Phys. Chem. 1971, 75, 991.
(50) Nakamaru, K. Bull. Chem. Soc. J pn. 1982, 55, 2697.
(51) Bao, Z.; Chen, Y.; Cai, R.; Yu, L. Macromolecules 1993, 26, 5281.
(52) Potts, K. T.; Konwar, D. J . Org. Chem. 1991, 56, 4815.
(53) Grosshenny, V.; Ziessel, R. J . Organomet. Chem. 1993, 453, 19.
(54) Coulson, D. R. Inorg. Synth. 1972, 13, 121.

Synthesis of Soluble Bis-terpyridine Ligands
J . Org. Chem., Vol. 65, No. 10, 2000 3133
gel with hexane/CH2Cl2 (70/30) as eluant and afforded 7 0.052
g (50%): mp 82-3 °C; 1H NMR (CDCl3) δ 0.89 (m, CH3, 18H),
1.28 (m, CH2, 108H), 1.87 (m, CH2, 12H), 3.98 (m, OCH2, 12H),
6.98 (s, Ph, 2H), 7.00 (s, Ph, 2H), 7.10 (s, Ph, 2H); 13C NMR
(CDCl3) δ 14.1, 22.7, 26.0, 29.4, 31.9, 69.7, 70.0, (90.6, 90.9,
CtC), 113.3, 114.3, 117.3, 117.7, 118.3, 153.5, 154.1; FT-IR
(KBr, cm-1) 2923 (s), 2851 (s), 1465 (s), 1217 (s); UV-vis (CH2-
Cl2) λ nm (ꢀ, M-1 cm-1) 252 (5800), 304 (25 400), 340 (20 000),
385 (43 600); FAB+ m/z (nature of the peak, relative intensity)
1541 ([M + H]+, 100), 1461 ([M - Br]+, 25), 1462 ([M - Br +
H]+, 15). Anal. Calcd for C94H156O6Br2: C, 73.22; H, 10.20.
Found: C, 73.01; H, 9.87.
149.1, 153.4, 153.5, 153.9, 155.4, 155.7; FT-IR (KBr, cm-1) 2925
(s), 2855 (s), 2208 (m, CtC), 1274 (s), 1213 (s), 1110 (s); UV-
vis (CH2Cl2): λ nm (ꢀ, M-1 cm-1) 244 (37 600), 255 (43 900),
299 (71 300), 385 (72 100); FAB+ m/z (nature of the peak,
relative intensity) 1250 ([M + H]+, 100), 1251 ([M + 2H]+, 74),
1168 ([M - Br]+, 65), 936 ([M - Br-terpy]+, 12). Anal. Calcd
for C79H114N3O4Br: C, 75.93; H, 9.19; N, 3.36. Found: C, 75.82;
H, 8.95; N, 3.25.
1-(2,2′:6′,2′′-Ter p yr id in e-4′-ylet h yn yl)-4-[1-yl-et h yn yl-
-2,5-d i(d od e cyloxy)b e n ze n e -4-[1-yl-e t h yn yl-2,5-d id o-
d ecyloxy)-4-(1-yl-et h yn yl-2,5-d id od ecyloxy)b en zen e-4-
br om o)]]-2,5-d id od ecyloxy)ben zen e (8). This compound
was prepared according to experimental conditions 1, from
0.036 g (0.02 mmol) of 4, 15 mL of n-propylamine, 0.017 g (0.04
mmol) of 6, and 0.002 g (0.002 mmol) of [Pd(PPh3)4]. The
reaction mixture was heated during 4 days at 70 °C. Purifica-
tion was performed by chromatography on alumina with CH 2-
Cl2 as eluant and afforded 0.024 g of 8 (47%): mp 120-1 C;
1H NMR (CDCl3) δ 0.88 (m, CH3, 24H), 1.26 (m, CH2, 144H),
1.88 (m, CH2, 16H), 4.02 (m, OCH2, 16H), 7.01 (m, Ph, 8H),
7.36 (ddd, J ) 7.6, 5.9, 1.2 Hz, 2H), 7.87 (td, J ) 7.6, 1.2 Hz,
2H), 8.59 (s, 2H), 8.65 (d, J ) 8.0 Hz, 2H), 8.73 (m, 2H); 13C
NMR (CDCl3) δ 14.3, 22.8, 23.5, 24.3, 25.0, 26.1, 26.3, 29.5,
29.6, 29.8, 32.1, 68.8, 69.8, 70.0, (89.7, 90.0, 90.8, 91.5, 91.7,
91.8, 92.1, 92.9, CtC), 113.2, 114.1, 114.2, 114.3, 114.5, 114.6,
114.7, 115.4, 116.7, 117.4, 117.5, 117.6, 118.6, 121.3, 122.9,
124.0, 133.7, 137.0, 149.3, 153.0, 153.7, 154.1, 155.6, 155.9;
FT-IR (KBr, cm-1) 2959 (s), 2924 (s), 2854 (s), 2209 (w, CtC),
1-(2-Meth yl-3-bu tyn -2-ol)-4-(2,2′:6′,2′′-ter p yr id in e-4-yl-
eth yn yl)-2,5-d id od ecyloxyben zen e (5). This compound was
prepared according to experimental conditions 2, from 0.200
g (0.36 mmol) of 1-(2-methyl-3-butyn-2-ol)-4-ethynyl-2,5-di-
dodecyloxybenzene 3, 0.381 g (0.44 mmol) of 4′-[[(trifuoro-
methyl)sulfonyl]oxy]-2,2′:6′,6′′-terpyridine, 20 mL of benzene,
0.025 g (0.022 mmol) of [Pd(PPh3)4], and 3.5 mL of diisopro-
pylamine. The reaction mixture was heated at 60 °C during
40 h. Purification was performed by chromatography on
alumina with CH2Cl2 as eluant and afforded 0.197 g of 5
(70%): mp 72-3 °C; 1H NMR (CDCl3) δ 0.87 (m, CH3, 6H),
1.27 (m, CH2, 36H), 1.63 (s, CH3, 6H), 1.83 (m, CH2, 4H), 2.39
(s, OH, 1H), 3.99 (td, J ) 6.2, 1.2 Hz, OCH2, 4H), 6.86 (s, Ph,
1H), 6.92 (s, Ph, 1H), 7.34 (ddd, J ) 7.4, 5.8, 1.0 Hz, 2H), 7.86
(td, J ) 7.8, 1.8 Hz, 2H), 8.59 (s, 2H), 8.64 (d, J ) 8.8 Hz, 2H),
8.72 (m, 2H); 13C NMR (CDCl3) δ 14.0, 22.6, 25.9, 26.1, 29.3,
29.4, 29.6, 31.4, 31.8, 65.5, 69.4, 69.6, (78.3, 90.4, 92.5, 99.7,
CtC), 112.9, 114.3, 117.1, 121.1, 122.7, 123.8, 128.3, 128.5,
131.9, 132.1, 133.4, 136.7, 149.0, 153.4, 153.7, 155.4, 155.6;
FT-IR (KBr, cm-1) 2924 (s), 2854 (s), 2214 (w, CtC), 1467 (s),
1264 (s), 1099 (s), 1025 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1
)
298 (24 900), 322 (22 100), 400 (37 700); FAB+ m/z (nature of
the peak, relative intensity) 2186 ([M]+, 98), 2187 ([M + H]+,
100), 2105 ([M - Br]+, 20), 1873 ([M - Br-terpy]+, <5). Anal.
Calcd for C143H218N3O8Br: C, 78.53; H, 10.05; N, 1.92. Found:
C, 78.39; H, 9.80; N, 1.89.
1390 (s), 1214 (s), 1111 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1
)
245 (16 600), 252 (22 500), 287 (30 100), 311 (14 800), 364
(13 600); FAB+ m/z (nature of the peak, relative intensity) 784
([M + H]+, 100), 724 ([M - C(CH3)2OH]+, 50), 492 ([M -
C(CH3)2OH-terpy]+, 10). Anal. Calcd for C52H69N3O3: C, 79.65;
H, 8.87; N, 5.36. Found: C, 79.56; H, 8.81; N, 5.30.
Syn th esis of Rigid Rod lik e Liga n d s. Liga n d I. This
compound was prepared according to experimental conditions
2, from 0.648 g (0.13 mmol) of 1,4-diethynyl-2,5-didodecyloxy-
benzene 2, 0.100 g (0.26 mmol) of 4′-[[(trifuoromethyl) sulfonyl]-
oxy]-2,2′:6′,6′′-terpyridine, 12 mL of benzene, 0.009 g (0.016
mmol) of [Pd(PPh3)4], and 3 mL of diisopropylamine. The
reaction mixture was heated at 60 °C during 3 days. Purifica-
tion was performed by chromatography on alumina with CH 2-
Cl2 as eluant and afforded 0.100 g (80%) of ligand I: mp 167-8
°C; 1H NMR (CDCl3) δ 0.85 (t, J ) 6.5 Hz, CH3, 6H), 1.27 (m,
CH2, 36H), 1.93 (m, CH2, 4H), 4.10 (t, J ) 6.5 Hz, OCH2, 4H),
7.09 (s, Ph, 2H), 7.36 (ddd, J ) 7.5, 5.9, 1.1 Hz, 4H), 7.88 (td,
J ) 7.9, 1.9 Hz, 4H), 8.60 (s, 4H), 8.61 (d, J ) 8.9 Hz, 4H),
8.73 (m, 4H); 13C NMR (CDCl3) δ 14.1, 22.6, 26.1, 29.4, 29.6,
31.9, 69.8, (90.4, 93.1, CtC), 114.0, 117.4, 121.1, 122.8, 123.9,
133.4, 136.7, 149.1, 153.8, 155.5, 155.7; FT-IR (KBr, cm-1) 2922
(s), 2852 (s), 2212 (m, CtC), 1575 (s), 1466 (s), 1389 (s), 1212
(s); UV-vis (CH2Cl2): λ nm (ꢀ, M-1 cm-1) 244 (45 200), 286
(46 400), 314 (39 700), 327 (37 900), 383 (29 600); FAB+ m/z
(nature of the peak, relative intensity) 958.0 ([M + H]+, 100),
789 ([M - C12H25 + H]+, 6), 647 ([M - terpy-py]+, 13), 619
([M - 2C12H25]+, 58). Anal. Calcd for C64H72N6O2: C, 80.30;
H, 7.58; N, 8.78. Found: C, 80.05; H, 7.29; N, 8.43.
Liga n d II1. This ligand was prepared according to experi-
mental conditions 1, from 0.071 g (0.06 mmol) of 7, 20 mL of
n-propylamine, 0.018 g (0.07 mmol) of 4′-ethynyl-2,2′:6′,6′′-
terpyridine, and 0.005 g (0.004 mmol) of [Pd(PPh3)4]. The
reaction mixture was heated for 3 days at 60 °C. Purification
was performed by chromatography on alumina with CH2Cl2
as eluant and afforded 0.072 g of liagnd II1 (70%): mp 172-3
°C; 1H NMR (CDCl3) δ 0.88 (m, CH3, 12H), 1.26 (m, CH2, 72H),
1.90 (m, CH2, 8H), 4.06 (m, OCH2, 8H), 7.05 (m, Ph, 4H), 7.36
(ddd, J ) 7.5, 5.9, 1.1 Hz, 4H), 7.88 (td, J ) 7.9, 1.9 Hz, 4H),
8.61 (s, 4H), 8.65 (d, J ) 8.9 Hz, 4H), 8.73 (m, 4H); 13C NMR
(CDCl3) δ 14.2, 22.8, 26.1, 26.3, 29.5, 29.8, 32.0, 32.1, 69.9,
(90.7, 91.9, 92.9, CtC), 113.3, 115.3, 117.3, 117.6, 121.3, 122.9,
124.0, 133.7, 137.0, 149.3, 153.6, 154.0, 155.6, 155.9; FT-IR
(KBr, cm-1) 2925 (s), 2854 (s), 2205 (m, CtC), 1576 (s), 1463
(s), 1215 (s), 1107 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1) 284
(54 600), 323 (44 000), 408 (58 300); FAB+ m/z (nature of the
peak, relative intensity) 1426 ([M]+, 100), 1340 ([M - C6H13
1-(2,2′:6′,2′′-Ter p yr id in e-4-yleth yn yl)-4-eth yn yl-2,5-d i-
d od ecyloxyben zen e (6). This compound was prepared ac-
cording to experimental conditions 4a, from 5 0.150 g (0.19
mmol), 1 g of NaOH (excess), and 30 mL of benzene. The
reaction mixture was heated during 36 h at 80 °C. Purification
was performed by chromatography on alumina with CH2Cl2
as eluant and affored 0.096 g of 6 (70%): mp 68-9 °C; 1H NMR
(CDCl3) δ 0.89 (m, CH3, 6H), 1.28 (m, CH2, 36H), 1.85 (m, CH2,
4H), 3.38 (s, CtCH, 1H), 4.07 (td, J ) 6.2, 1.2 Hz, OCH2, 4H),
6.95 (s, Ph, 1H), 7.05 (s, Ph, 1H), 7.35 (ddd, J ) 7.5, 6.0, 1.1
Hz, 2H), 7.87 (td, J ) 7.5, 1.1 Hz, 2H), 8.60 (s, 2H), 8.64 (d, J
) 8.8 Hz, 2H), 8.73 (m, 2H); 13C NMR (CDCl3) δ 14.0, 22.6,
25.9, 26.1, 29.1, 29.3, 29.4, 29.6, 31.8, 69.5, 69.7, (79.9, 82.6,
90.2, 92.8, CtC), 113.5, 113.7, 117.1, 117.8, 121.0, 122.7, 123.8,
133.3, 136.7, 149.0, 153.7, 154.0, 155.4, 155.6; FT-IR (KBr,
cm-1) 2925 (s), 2851 (s), 2208 (m, CtC), 1576 (s), 1469 (s), 1391
(s), 1217 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1) 245 (27 600),
252 (29 800), 287 (61 200), 309 (48 400), 361 (29 600); FAB+
m/z (nature of the peak, relative intensity) 726 ([M + H]+, 100),
493 ([M - terpy]+, 15). Anal. Calcd for C49H63N3O2: C, 81.06;
H, 8.75; N, 5.79. Found: C, 80.82; H, 8.53; N, 5.45.
1-(4′-Eth yn yl-2,2′:6′,2′′-ter p yr id in e)-4-[1-br om o-2,5-(d o-
d ecyloxy)ben zen e-4-yleth yn yl]-2,5-d id od ecyloxyben zen e
(7). This compound was prepared according to experimental
conditions 1 from 0.150 g (0.21 mmol) of 6, 0.150 (0.25 mmol)
of 1,4-dibromo-2,5-(dodecyloxy)benzene, 0.015 g (0.013 mmol)
of [Pd(PPh3)4], and 30 mL of n-propylamine. The reaction
mixture was heated during 4 days at 70 °C. Purification was
performed by chromatography on alumina with CH2Cl2 as
eluant and afforded 0.162 g of 7 (62%): mp 84-5 °C; 1H NMR
(CDCl3) δ 0.87 (m, CH3, 12H), 1.25 (m, CH2, 72H), 1.88 (m,
CH2, 8H), 4.02 (m, OCH2, 8H), 7.00 (s, Ph, 2H), 7.03 (s, Ph,
1H), 7.06 (s, Ph, 1H), 7.36 (ddd, J ) 7.6, 5.9, 1.2 Hz, 2H), 7.87
(td, J ) 7.6, 1.2 Hz, 2H), 8.59 (s, 2H), 8.65 (d, J ) 8.0 Hz, 2H),
8.73 (m, 2H); 13C NMR (CDCl3) δ 14.0, 22.6, 26.0, 26.1, 29.3,
29.4, 29.6, 31.9, 69.7, (90.6, 91.5, 91.9, 92.8, CtC), 113.1, 114.3,
117.1, 115.2, 117.3, 117.4, 121.1, 122.7, 123.9, 133.5, 136.8,

3134 J . Org. Chem., Vol. 65, No. 10, 2000
Khatyr and Ziessel
+ H]+, 27). Anal. Calcd for C96H124N6O4: C, 80.86; H, 8.76; N,
5.89. Found: C, 80.53; H, 0.8.47; N, 5.72.
Cl2/CH3CO2C2H5 (0-10%) as eluant and afforded 0.016 g of
IV (72%): mp 155-6 °C; 1H NMR (CDCl3) δ 0.88 (m, CH3,
24H), 1.26 (m, CH2, 144H), 1.90 (m, CH2, 16H), 4.06 (m, OCH2,
16H), 7.05 (m, Ph, 8H), 7.36 (ddd, J ) 7.5, 5.9, 1.1 Hz, 4H),
7.88 (td, J ) 7.9, 1.9 Hz, 4H), 8.61 (s, 4H), 8.65 (d, J ) 8.9 Hz,
4H), 8.73 (m, 4H); 13C NMR (CDCl3) δ 14.1, 22.7, 26.1, 26.2,
27.1, 29.4, 29.5, 29.7, 32.0, 69.7, (90.7, 91.5, 91.7, 92.0, 92.8,
CtC), 113.1, 114.3, 114.5, 115.3, 117.3, 117.5, 121.2, 122.8,
124.0, 133.7, 136.9, 149.2, 153.4, 153.5, 153.6, 154.0, 155.5,
155.8; FT-IR (KBr, cm-1) 3417 (s), 2924 (s), 2854 (s), 2208 (w,
Liga n d II2. This compound was prepared according to
experiemental conditions 3, from 0.030 g (0.04 mmol) of 6, 10
mL of acetonitrile, 0.002 g (0.02 mmol) of CuCl, and 0.003 mL
(0.02 mmol) of TMEDA. The reaction mixture was stirred
under O2 at room temperature for 5 days. Purification was
performed by chromatography on alumina with CH2Cl2 as
1
eluant to give 0.022 g of ligand II2 (74%): mp 102-3 °C; H
NMR (CDCl3) δ 0.88 (m, CH3, 12H), 1.27 (m, CH2, 72H), 1.89
(m, CH2, 8H), 4.05 (t, J ) 5.8 Hz, OCH2, 8H), 7.03 (s, Ph, 2H),
7.05 (s, Ph, 2H), 7.35 (ddd, J ) 7.7, 5.9, 1.1 Hz, 4H), 7.89 (td,
J ) 7.7, 1.9 Hz, 4H), 8.59 (s, 4H), 8.61 (d, J ) 8.0 Hz, 4H),
8.73 (m, 4H); 13C NMR (CDCl3) δ 14.1, 22.7, 26.0, 26.2, 29.2,
29.4, 29.7, 31.9, 69.8, (79.6, 90.3, 91.9, 93.4, CtC), 113.5, 114.3,
117.3, 117.8, 121.2, 122.8, 124.0, 133.4, 136.8, 140.5, 149.2,
153.8, 155.0, 155.5, 155.8; FT-IR (KBr, cm-1) 2923 (s), 2852
(s), 2210 (w, CtC), 1577 (s), 1389 (s), 1215 (s); UV-vis (CH2-
Cl2) λ nm (ꢀ, M-1 cm-1) 245 (31 700), 250 (31 800), 299 (52 800),
322 (54 400), 406 (75 800); FAB+ m/z (nature of the peak,
relative intensity) 1450 ([M]+, 24), 1112 ([M - 2C12H25 + H]+,
7), 958 ([M - 2 C12H25 - 2py + 3H]+, 100). Anal. Calcd for
CtC), 1627 (s), 1108 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1 cm-1
)
286 (31 400), 321 (24 900), 424 (45 200); FAB+ m/z (nature of
the peak, relative intensity) 2363 ([M + H]+,100), 2177 ([M -
OC12H25 + H]+, 30), 1992 ([M - 2OC12H25 + H]+, 15). Anal.
Calcd for C160H228N6O8: C, 81.31; H, 9.72; N, 3.56. Found: C,
81.02; H, 9.52; N, 3.22.
Liga n d V. This ligand was prepared following experimental
conditions 1, from 0.050 g (0.03 mmol) of 4, 20 mL of
n-propylamine, 0.047 g (0.06 mmol) of 6, and 0.005 g (0.004
mmol) of [Pd(PPh3)4]. The reaction mixture was heated during
5 days at 70 °C. Purification was performed by chromatogra-
phy on alumina using CH2Cl2/CH3CO2C2H5 (0-20%) as eluant
and afforded 0.064 g of V (70%): mp 142-3 °C; 1H NMR
(CDCl3) δ 0.87 (m, CH3, 30H), 1.26 (m, CH2, 180H), 1.89 (m,
CH2, 20H), 4.07 (m, OCH2, 20H), 7.04 (m, Ph, 10H), 7.38 (ddd,
J ) 7.5, 5.9, 1.1 Hz, 4H), 7.88 (td, J ) 7.5, 1.9 Hz, 4H), 8.59
(s, 4H), 8.61 (d, J ) 8.0 Hz, 4H), 8.73 (m, 4H); 13C NMR (CDCl3)
δ 14.1, 22.7, 23.0, 23.8, 26.0, 26.2, 28.9, 29.4, 29.5, 29.7, 30.4,
31.9, 38.7, 68.1, 69.7, (90.7, 91.4, 91.6, 92.0, 92.8, 93.5, CtC),
113.1, 117.3, 121.2, 122.8, 123.9, 127.6, 128.3, 128.6, 130.8,
132.0, 132.2, 133.6, 136.8, 149.2, 153.6, 154.0, 155.5, 155.8;
FT-IR (KBr, cm-1) 3472 (s), 3416 (s), 2924 (s), 2853 (s), (2207
(w), CtC), 1216 (s), 1107 (s); UV-vis (CH2Cl2) λ nm (ꢀ, M-1
cm-1) 245 (25 900), 252 (26 200), 285 (27 900), 321 (28 000),
433 (43 700); FAB+ m/z (nature of the peak, relative intensity)
2831.8 ([M + H]+, 100), 2645.8 ([M - OC12H25 + H]+, 20),
C
98H124N6O4: C, 81.17; H, 8.62; N, 5.80. Found: C, 81.07; H,
8.52; N, 5.64.
Liga n d III. This ligand was prepared according to experi-
mental conditions 1, from 0.036 g (0.02 mmol) of 4, 15 mL of
n-propylamine, 0.014 g (0.06 mmol) of 4′-ethynyl-2,2′:6′,6′′-
terpyridine, and 0.004 g (0.003 mmol) of [Pd(PPh3)4]. The
reaction mixture was heated during 5 days at 70 °C. Purifica-
tion was performed by chromatography on alumina with CH 2-
Cl2 as eluant to give 0.030 g of ligand III (68%): mp 182-3
°C; 1H NMR (CDCl3) δ 0.84 (m, CH3, 18H), 1.26 (m, CH2,
108H), 1.90 (m, CH2, 12H), 4.05 (m, OCH2, 12H), 6.98 (s, Ph,
2H), 7.00 (s, Ph, 2H), 7.07 (s, Ph, 2H), 7.36 (ddd, J ) 7.5, 5.9,
1.1 Hz, 4H), 7.88 (td, J ) 7.9, 1.9 Hz, 4H), 8.61 (s, 4H), 8.65
(d, J ) 8.9 Hz, 4H), 8.73 (m, 4H); 13C NMR (CDCl3) δ 14.1,
22.7, 26.1, 26.2, 29.4, 29.5, 29.7, 32.0, 69.8, (90.7, 91.5, 92.0,
92.8, CtC), 113.1, 114.4, 115.3, 117.2, 117.5, 121.2, 122.8,
123.9, 133.6, 136.8, 149.2, 153.5, 153.6, 154.0, 155.5, 155.8;
FT-IR (KBr, cm-1) 2924 (s), 2854 (s), (2207 (m), CtC), 1589
(s), 1464 (s), 1432 (s), 1391 (s), 1108 (s); UV-vis (CH2Cl2) λ
nm (ꢀ, M-1 cm-1) 245 (27 500), 251 (28 400), 268 (34 800), 322
(27 000), 419 (45 000); FAB+ m/z (nature of the peak, relative
intensity) 1895 ([M + H]+, 100). Anal. Calcd for C128H176N6O6:
C, 81.14; H, 9.36; N, 4.44. Found: C, 80.82; H, 9.13; N, 4.29.
Liga n d IV. This ligand was prepared according experimen-
tal conditions 1, from 0.020 g (0.01 mmol) of 8, 15 mL of
n-propylamine, 0.003 g (0.01 mmol) of 4′-ethynyl-2,2′:6′,6′′-
terpyridine, and 0.001 g (0.001 mmol) of [Pd(PPh3)4]. The
reaction mixture was heated during 2 days at 70 °C. Purifica-
tion was performed by chromatography on alumina using CH2-
2459.8 ([M - 2OC12H25 + H]+, 10). Anal. Calcd for C192H280
-
N6O10: C, 81.42; H, 9.96; N, 2.97. Found: C, 81.18; H, 9.72;
N, 2.82.
Ack n ow led gm en t. We warmly thank Professor
Anthony Harriman for a critical reading of the manu-
script and Dr. Lo¨ıc Charbonnie`re for his suggestion
concerning the effect of molecular oxygen on a potential
triplet state and for helpful discussions. The present
work was supported by the Centre National de la
Recherche Scientifique and by the Engineer School of
Chemistry in Strasbourg (ECPM).
J O9919355