High molecular weight CuII coordination polymers and their characterisation by electrospray mass spectrometry (ESMS)

Article abstract of DOI:10.1002/1099-0682(200203)2002:3<573::AID-EJIC573>3.0.CO;2-R

The ligands L and ligand L* self-assemble with Cu^II in different solvents to give a mixture of coordination polymers. These artificial nanostructures have been characterised with the help of ESMS, the only analytical tool that allows their unambiguous characterisation. Kinetic and thermodynamic ESMS studies have excluded the possibility that these compounds form aggregates during the ES process.

Full text of DOI:10.1002/1099-0682(200203)2002:3<573::AID-EJIC573>3.0.CO;2-R

FULL PAPER
High Molecular Weight CuII Coordination Polymers and Their
Characterisation by Electrospray Mass Spectrometry (ESMS)
[a]
[b]
[a]
[b]
´ `
Helene Nierengarten, Javier Rojo, Emmanuelle Leize,* Jean-Marie Lehn, and
Alain Van Dorsselaer[a]
Keywords: Supramolecular chemistry / Copper / Polymers / Mass spectrometry / Self-assembly
The ligands L and ligand L* self-assemble with CuII in differ-
ent solvents to give a mixture of coordination polymers. ESMS studies have excluded the possibility that these com-
unambiguous characterisation. Kinetic and thermodynamic
These artificial nanostructures have been characterised with
the help of ESMS, the only analytical tool that allows their
pounds form aggregates during the ES process.
Introduction
perspectives are offered by the use of electrospray mass
spectrometry (ESMS)[4] for an unequivocal characteris-
The self-assembly of suitably designed organic ligands ation. ESMS has been proven to be a very useful technique
with transition-metal ions allows the generation of a wide for the characterisation of biological[5] and chemical[6] as-
range of polymetallic complexes possessing a variety of semblies. Moreover, this analytical method is particularly
well-defined architectures (racks, ladders, grids, rings, suitable for large, noncovalent species with high molecular
etc.).[1,2] These organised entities, and especially coordina- masses. Indeed, when several parameters are carefully con-
tion polymers, may present interesting physical and chem- trolled, ESMS is a mild method, which causes minimum
ical properties and are of much current interest within fragmentation and therefore allows molecular mass deter-
metallosupramolecular chemistry due to their potential ap- mination.
plications in materials science.[3] One of the challenges in
We describe here the characterisation in solution by
this field resides in the preparation of high molecular ESMS of the largest reported CuII coordination polymers
weight coordination polymers that may possess good solu- stable in solution up to a concentration of 10Ϫ4  and sol-
bilities in order to characterise their properties in solution uble in common organic solvents (acetonitrile, methanol,
as well as in the solid state. Unfortunately, an unequivocal nitromethane). In this present case, ESMS was the only
structural analysis of these metallosupramolecular com- analytical tool allowing an unambiguous characterisation.
pounds is often missing. Indeed, because of the complexity Therefore, kinetic and thermodynamic studies have been
of the NMR spectra and because of the recurrent presence undertaken in order to exclude the possibility that these co-
of paramagnetic metals, NMR spectroscopy is often unus- ordination polymers are aggregates resulting from the ES
able. In the same way, X-ray suitable crystals of sufficient process.[7]
quality are often difficult to obtain; the use of X-ray crys-
tallography is therefore limited. The other classical analyt-
ical tools able to give any information are in most cases
inconclusive with respect to the formulation (e.g., UV/Vis
absorption and emission spectroscopy, infrared, etc.).
Results and Discussion
The ligand L was synthesised following the procedure
An unambiguous characterisation is therefore highly com- outlined in Scheme 1. The self-assembly reaction to obtain
promised. Despite the problems and difficulties that often the CuII coordination polymers was carried out as follows:
occur during the development of this chemistry (especially an equimolar amount of the ligand L and Cu(CF3SO3)2
due to the increasing size of such molecules), encouraging were mixed together in anhydrous acetonitrile (ca. 10Ϫ4 ),
the mixture was stirred at room temperature for five mi-
nutes and a clear blue solution was obtained.
[a]
´
Laboratoire de Spectrometrie de Masse Bio-Organique,
´
Universite Louis Pasteur, CNRS UMR 7509, ECPM,
The analysis of this solution by ESMS immediately after
preparation has shown the presence of coordination com-
plexes of general formula [LCu(CF3SO3)2]n, Mn, in equilib-
rium in solution (Figure 1). Ions observed in the ES mass
spectrum (Mnxϩ; 1 Յ n Յ 47 and 1 Յ x Յ 4) are interpreted
25 rue Becquerel, 67087 Strasbourg cedex 2, France
Fax: (internat.) ϩ33-(0)3/9024-2781
E-mail: leize@chimie.u-strasbg.fr
[b]
´
´
Laboratoire de Chimie Supramoleculaire, ISIS, Universite
Louis Pasteur, ESA CNRS 7006,
4 rue Blaise Pascal, 67000 Strasbourg cedex, France
Eur. J. Inorg. Chem. 2002, 573Ϫ579
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
1434Ϫ1948/02/0303Ϫ0573 $ 17.50ϩ.50/0
573

H. Nierengarten, J. Rojo, E. Leize, J.-M. Lehn, A. Van Dorsselaer
FULL PAPER
mass spectra obtained were reproducible (Ϯ10%) and ident-
ical in terms of relative intensities of the different peaks
on four different instruments [Quattro II, LC-Tof, Q-Tof
(Micromass, Altrincham, UK) and ESQUIRE-LC (Bruker-
Franzen Analytik GmbH, Bremen, Germany)]. All the ions
observed were interpreted and are summarised with their
m/z values and their charge states in Table 1.
Scheme 1. i, nBuLi, THF, Ϫ78 °C; Bu3SnCl, Ϫ78 °C, 96%;
ii, nBuLi, ether, Ϫ90 °C; ClCO2Et, 47%; iii, Pd(PPh3)4, toluene,
110 °C, 50Ϫ76%
Figure 2. High resolution spectrum, obtained on an LC-Tof spec-
trometer
as the successive loss of x counter anions CF3SO3Ϫ (ϪOTf),
leading to multiply charged ions, and correspond to mo-
lecular masses up to 32901.4 Da (n ϭ 47).
These ESMS results in acetonitrile and the stoichi-
ometries determined suggest that in all complexes four ni-
The charge states of these ions were unambiguously de- trogen donor atoms coordinate one CuII. The IR analysis
termined owing to the high-resolution capability of a time showed only a slight change in the CϭO vibration fre-
of flight analyser (Figure 2). Charge states of these ions quency between the ligand and the mixture of complexes —
range from x ϭ 1ϩ to x ϭ 4ϩ. The largest polymer (n ϭ from 1686 cmϪ1 to 1679 cmϪ1 — suggesting that the car-
47) has been identified owing to its 4ϩ charged ion at bonyl group does not participate in the coordination with
m/z ϭ 8076.0 (see the ES mass spectra, Figure 1). The ES CuII. Since CuII is normally pentacoordinated, if we assume
Figure 1. ES mass spectrum (obtained on an LC-Tof spectrometer) of an equimolar mixture of L and Cu(CF3SO3)2 in anhydrous
acetonitrile at 10Ϫ4

574
Eur. J. Inorg. Chem. 2002, 573Ϫ579

High Molecular Weight CuII Coordination Polymers
FULL PAPER
Table 1. Identification of the Mn (1 Ͻ n Ͻ 47) ions detected by ESMS[a]
M1
M2
M3
M4
M5
M6
M7
M8
M9
M10
551.0 (1ϩ)
550.97
1250.9 (1ϩ) 1950.9 (1ϩ) 2650.9 (1ϩ) 3351.3 (1ϩ) 4050.9 (1ϩ) 4751.1 (1ϩ) 5451.2 (1ϩ) 6150.3 (1ϩ) 6851.9 (1ϩ)
1251.0
1951.03
2651.06
3351.09
4051.12
4751.15
5451.18
6151.21
6851.24
2650.9 (2ϩ) 3000.8 (2ϩ) 3351.3 (2ϩ)
2651.06
3001.08
3351.10
M11
M12
M13
M14
M15
M16
M17
M18
M19
M20
7550.6 (1ϩ) 8250.9 (1ϩ) 8949.8 (1ϩ) 9650.1 (1ϩ) 10353.1 (1ϩ) 11048.1 (1ϩ) 5801.1 (2ϩ) 6150.3 (2ϩ) 6500.3 (2ϩ) 6851.9 (2ϩ)
7551.27 8251.30 8951.33 9651.36 10351.39 11051.42 5801.19 6151.21 6501.22 6851.24
3700.7 (2ϩ) 4050.9 (2ϩ) 4400.4 (2ϩ) 4751.1 (2ϩ) 5100.6 (2ϩ) 5451.2 (2ϩ) 3817.5 (3ϩ) 4050.9 (3ϩ) 4284.6 (3ϩ) 4517.4 (3ϩ)
3701.91
4051.12
4401.14
4751.15
5101.16
5451.18
3817.77
4051.12
4284.46
4517.80
M21
M22
M23
M24
M25
M26
M27
M28
M29
M30
7200.0 (2ϩ) 7550.6 (2ϩ) 7901.0 (2ϩ) 8250.9 (2ϩ) 8601.1 (2ϩ) 8949.8 (2ϩ) 9300.6 (2ϩ) 9650.1 (2ϩ) 10001.9 (2ϩ) 10353.1 (2ϩ)
7201.25 7551.27 7901.28 8251.30 8601.31 8951.33 9301.34 9651.36 10001.37 10351.39
4751.1 (3ϩ) 4984.4 (3ϩ) 5217.2 (3ϩ) 5451.2 (3ϩ) 5684.2 (3ϩ) 5917.0 (3ϩ) 6150.3 (3ϩ) 6384.0 (3ϩ) 6617.9 (3ϩ) 6851.9 (3ϩ)
4751.15
4984.49
5217.83
5451.18
5684.52
5917.86
6151.21
6384.55
6617.89
6851.24
M31
M32
M33
M34
M35
M36
M37
M38
M39
M40
7084.58 (3ϩ) 7317.8 (3ϩ) 7550.6 (3ϩ) 7784.5 (3ϩ) 8017.8 (3ϩ) 8250.9 (3ϩ) 8485.5 (3ϩ) 8717.0 (3ϩ) 8949.8 (3ϩ) 6851.9 (4ϩ)
7085.0
7317.92
7551.27
7784.61
8017.95
8251.30
8484.64
8717.98
8951.33
6851.24
5276.2 (4ϩ) 5451.2 (4ϩ) 5626.2 (4ϩ) 5801.1 (4ϩ) 5976.6 (4ϩ) 6150.3 (4ϩ) 6326.6 (4ϩ) 6500.3 (4ϩ) 6676.2 (4ϩ)
5276.17
5451.18
5626.18
5801.19
5976.20
6151.21
6326.21
6501.22
6676.23
M31
M32
M33
M34
M35
M36
M37
M38
M39
M40
7084.58 (3ϩ) 7317.8 (3ϩ) 7550.6 (3ϩ) 7784.5 (3ϩ) 8017.8 (3ϩ) 8250.9 (3ϩ) 8485.5 (3ϩ) 8717.0 (3ϩ) 8949.8 (3ϩ) 6851.9 (4ϩ)
7085.0 7317.92 7551.27 7784.61 8017.95 8251.30 8484.64 8717.98 8951.33 6851.24
5276.2 (4ϩ) 5451.2 (4ϩ) 5626.2 (4ϩ) 5801.1 (4ϩ) 5976.6 (4ϩ) 6150.3 (4ϩ) 6326.6 (4ϩ) 6500.3 (4ϩ) 6676.2 (4ϩ)
5276.17
5451.18
5626.18
5801.19
5976.20
6151.21
6326.21
6501.22
6676.23
M41
M42
M43
M44
M45
M46
M47
7026.1 (4ϩ) 7200.0 (4ϩ) 7376.2 (4ϩ) 7550.6 (4ϩ) 7726.1 (4ϩ) 7901.0 (4ϩ) 8076.0 (4ϩ)
7026.24
7201.25
7376.26
7551.27
7726.27
7901.28
8076.29
[a]
Measured m/z (charge state) and calculated m/z in italics.
that four nitrogen donor atoms coordinate one CuII, the formation could be obtained on the number of molecules
fifth coordination position is probably occupied by a molec- of solvent attached to these large ions.
ule of solvent in order to complete the metal coordination
sphere. In fact an acetonitrile molecule is probably coordin-
Slow crystallisation of these oligomers was unsuccessful
and only crystals corresponding to the monomer (M1)
ated to the CuII in solution but is lost in the gas phase.
To confirm this possible coordination cell, ESMS studies structure were found. Thanks to the ESMS and IR data a
in anhydrous MeOH have been undertaken. Indeed, it has possible structure was deduced for these polymers in solu-
already been observed in the case of metallic complexes that tion (Figure 4). Obviously, a cyclic form cannot be distingu-
MeOH is a better coordinating solvent than acetonitrile in ished from a linear structure by mass measurement in our
the gas phase.[8] The ES mass spectrum (Figure 3) obtained case. However, the 1:1:1 (L:CuII:MeOH) stoichiometry ob-
in [D4]MeOH has confirmed the presence of solvent molec- tained for small oligomers (Mn, n ϭ 1 to n ϭ 5), suggests
ules attached to these high-molecular-weight complexes. the formation of cyclic compounds in solution. On the
[D4]MeOH was used in this case instead of MeOH to facil- other hand, considering the number of units, high polymers
itate the resolution of the different adducts. In these condi- (Mn, n Ͼ 5) should be present as open structures (linear
tions, for small oligomers (Mn, n ϭ 1 to n ϭ 5), the addition polymers). At both extremities the coordination sphere of
of one molecule of [D4]MeOH to each CuII atom is ob- CuII would be completed in solution by acetonitrile molec-
served from the m/z difference of 36 for singly charged ules, which are lost in the gas phase and not detected in
peaks and 18 for doubly charged peaks. Unfortunately, for the ESMS.
higher oligomers (Mn, n Ͼ 5) the ES mass spectrum is too
Considering that ESMS is the only analytical tool al-
complex at the resolution available (R ϭ 8000) and no in- lowing an unambiguous characterisation in this case, kin-
Eur. J. Inorg. Chem. 2002, 573Ϫ579
575

H. Nierengarten, J. Rojo, E. Leize, J.-M. Lehn, A. Van Dorsselaer
FULL PAPER
Figure 3. ES mass spectrum of an equimolar mixture of L and Cu(CF3SO3)2 in [D4]MeOH
way, when 5% water was added to one of these solutions,
the ES analysis after 5 minutes was unchanged. Later, peaks
corresponding to the higher oligomers progressively disap-
peared and after 24 hours only one peak corresponding to
the monomer complex (M11ϩ) was observed in the ES mass
spectrum (Figure 5a, b, c).
The observation of this progressive dissociation is the de-
finitive piece of evidence which shows that these high mo-
lecular weight coordination complexes are formed in solu-
tion and not during the ES process. Hence, the possibility
for these polymers of being artefacts of the ES process can
be definitely rejected.
Thermodynamic Studies
Attempts to isolate some of the oligomers using size ex-
clusion sephadex chromatography (by classical column or
by HPLC) were fruitless and unfortunately only the mono-
mer (M1) was obtained. This result indicates that all these
components are in equilibrium in solution. In order to de-
termine if ligand exchange took place in this high-molecu-
lar-weight system, the ligand L was first mixed with a stoi-
chiometric amount of Cu(OTf)2 in anhydrous acetonitrile
(ca. 10Ϫ4 ). Then, after stirring for 5 minutes, one equiva-
lent of the methylated ligand L* (Scheme 1) was added to
this mixture. The resulting solution was stirred for 5 mi-
nutes at room temperature and analysed immediately. The
ES mass spectrum (Figure 6) showed that all possible com-
binations of oligomers MaMb* (0 Ͻ a, b Ͻ 9) of general
formula LaLb*[Cu(CF3SO3)2]aϩb were obtained statistically
Figure 4. Possible structure of the coordination polymers [LCu-
(CF3SO3)2]n deduced from ESMS and IR data (solvent adducts are
omitted for clarity)
etic and thermodynamic studies were necessary in order to
exclude the possibility of these oligomers being artefacts re-
sulting from the ES process.
Kinetic Studies
The stability of the polymers in solution was tested dur- in solution. This observation clearly indicates that ligand
ing 40 days in several anhydrous solvents (acetonitrile, exchange occurred in solution, and confirms that these co-
nitromethane, and methanol). ES mass spectra obtained ordination polymers are in equilibrium in solution. Interest-
from the same sample immediately after mixing (5 minutes) ingly, the methylated ligand L* yielded a mixture of oligo-
and after 40 days were found to be the same, showing the mers with Cu(OTf)2 in anhydrous acetonitrile in the same
high stability of these compounds in solution. In the same manner as obtained with the ligand L.
576
Eur. J. Inorg. Chem. 2002, 573Ϫ579

High Molecular Weight CuII Coordination Polymers
FULL PAPER
To complete the study of these compounds, other ther- in solution, five solutions containing an equimolar amount
modynamic experiments were carried out. In order to ob- of Cu(OTf)2 and the ligand L in anhydrous acetonitrile at
tain more information about the stability of the complexes different concentrations (10Ϫ3, 10Ϫ4, 10Ϫ5, 10Ϫ6 and 10Ϫ7
) were analysed by ESMS. The ES mass spectra obtained
showed the presence of the oligomeric mixture for a concen-
tration down to 10Ϫ4 . For lower concentrations, these
high-molecular-weight complexes disappear and only the
monomer ion (M11ϩ) is detected, indicating that dissociation
processes occur below a concentration of 10Ϫ4  (Fig-
ure 7a, b).
Figure 5a, b, c. Kinetic study: a. in anhydrous acetonitrile after 40
days; b. in acetonitrile with 5% water after 5 min; c. in acetonitrile
with 5% water after 24 h; this study addresses the possibility that Figure 7a, b. Evaluation of the stability in solution of the coordina-
the compounds are ES process artefacts
tion polymers at different concentrations
Figure 6. ES mass spectrum of an equimolar mixture of L and Cu(CF3SO3)2 with one equivalent of L* in anhydrous acetonitrile at 10Ϫ4 
Eur. J. Inorg. Chem. 2002, 573Ϫ579 577

H. Nierengarten, J. Rojo, E. Leize, J.-M. Lehn, A. Van Dorsselaer
FULL PAPER
Conclusion
Synthesis of the Ligands L and L*: The ligands were prepared as
shown in Scheme 1. The stannylation of 2-bromopyridine (3) with
butyllithium and tributylstannyl chloride gave 2-tributylstannylpyr-
idine (4).[9] The ketone 6 was prepared from 2,6-dibromopyridine
(5) by monolithiation and reaction with ethylchloroformate as pre-
viously described.[10] The cross coupling reaction between 4 and 6
or 8 and 6 in the presence of Pd(PPh3)4 yielded ligand 1 (L) or
ligand 2 (L*) which were completely characterised.
We have shown that ligand L and Cu(CF3SO3)2 in a 1:1
ratio in anhydrous solvents generate a mixture of high mo-
lecular weight coordination polymers of general formula
[LCu(CF3SO3)2]n by self-assembly. The largest oligomer cle-
arly identified contains 47 units and weighs 32901.4 Da.
The structure (cyclic for small oligomers and linear for the
highest one) has been deduced from the IR and the ESMS
data.
The kinetic decomplexation observed in the presence of
5% water shows that these self-assembled polymeric species
are formed in solution and are not artefacts due to the ES
process. To complete this study, ESMS thermodynamic ex-
periments have been carried out and have demonstrated
that these oligomers are in equilibrium in solution, are
stable over time and can be observed down to a concentra-
tion of 10Ϫ4 .
2-Tributylstannylpyridine (4): A 1.6  solution of n-butyllithium in
hexane (39.2 mL, 0.062 mol) was slowly added to a solution of 2-
bromopyridine (3; 6 mL, 0.062 mol) in THF (120 mL) cooled to
Ϫ78 °C under argon. After 30 min, Bu3SnCl (16.8 mL, 0.062 mol)
was added to give a dark solution which was stirred at Ϫ78 °C
for one more hour. The solution was allowed to warm to room
temperature and a saturated aqueous solution of NH4Cl (60 mL)
was added. The aqueous phase was extracted with ether (3 ϫ 100
mL) and the combined organic layers were washed with brine (100
mL) and dried (Na2SO4). The solvent was removed under reduced
pressure to give a yellow oil. The crude product was purified by
chromatography on alumina (EtOAc/hexane 1:20) to obtain a pale
yellow oil (22.1 g, 96%).[9] 1H NMR: δ ϭ 8.73 (ddd, J ϭ 4.9, 1.9,
1.0 Hz, 1 H, H6), 7.48 (dt, J ϭ 7.4, 1.8 Hz, 1 H, H5), 7.39 (dt, J ϭ
7.4, 1.6 Hz, 1 H, H3), 7.10 (ddd, J ϭ 6.9, 4.9, 1.7 Hz, 1 H, H4),
1.70Ϫ1.05 (m, 18 H, CH2), 0.85 (t, 9 H, J ϭ 7.3 Hz, CH3).
ESMS may therefore be regarded as an extremely valu-
able tool to prove the existence of very large polynuclear
transition metal complexes in solution, and encouraging
perspectives are offered for the characterisation of species
of nanometric dimensions.
Bis(6-bromo-2-pyridyl)ketone (6): 1.1 Equiv. of n-butyllithium in
hexane (29 mL, 0.046 mol) was added dropwise under argon to a
solution of 2,6-dibromopyridine (5; 10 g, 0.042 mol) in diethyl ether
(200 mL) cooled to Ϫ90 °C. After stirring vigorously for 20 min,
a solution of ethyl chloroformate (2.02 mL, 0.021 mol) in diethyl
ether (50 mL) was added. The deep blue solution was stirred for
one hour and warmed to Ϫ40 °C for 30 min. Then, the reaction
was quenched successively with methanol (50 mL) and water (50
mL). The organic phase was removed under vacuum and the aque-
ous layer was extracted with chloroform (3 ϫ 50 mL). The com-
bined organic layers were dried (Na2SO4) and the solvent was re-
moved under low pressure. The residue was purified by flash chro-
matography on silica gel using EtOAc/hexane (1:6) as eluent to give
a white solid (3.4 g, 47%). M.p. 159Ϫ160 °C (ref.[10] 155Ϫ156.5 °C).
1H NMR: δ ϭ 8.08 (dd, J ϭ 7.1, 1.4 Hz, 2 H, H3), 7.76 (dd, J ϭ
8.0, 7.2 Hz, 2 H, H4), 7.69 (dd, J ϭ 8.0, 1.5 Hz, 2 H, H5). 13C
NMR: δ ϭ 189.5, 154.0, 141.5, 138.9, 131.4, 124.3.
Experimental Section
Materials: Unless otherwise noted, 1H NMR spectra were meas-
ured at 200 MHz with a Bruker AC 200 spectrometer in CDCl3
and referenced to the residual solvent peak. Melting points were
obtained with a digital Thomas Hoover (Electrotherma) apparatus.
Infrared absorption spectra were recorded on a PerkinϪElmer 1600
series FTIR spectrometer in KBr, and electronic absorption spectra
on a Cary 219 spectrometer in CHCl3 with λmax in nm and ε (ϫ
104) in Ϫ1 cmϪ1. Fast atom bombardment mass spectrometry
(FAB-MS) was performed on a ZAB-HF VG spectrometer with m-
nitrobenzyl alcohol as the matrix. Spectroscopic studies were per-
formed in spectroscopic-grade solvents. All solvents were reagent-
grade and used without further purification. The CuII triflate was
purchased from Fluka (Buchs, Switzerland).
2-Tributylstannyl-4-picoline (8): 1 Equiv. of a 1.6  solution of n-
butyllithium in hexane (18.15 mL, 29.066 mmol) was added at Ϫ78
ESMS: Positive ES mass spectra were mainly obtained on an ES
triple quadrupole mass spectrometer Quattro II with an m/z range
extended to 8000 (Micromass, Altrincham, UK). The electrospray
source was heated to 70 °C. The sampling cone voltage (Vc) was
set to 70 V and the skimmer Lens Offset to 0 V to allow the trans-
mission of ions with m/z Ͼ 4000 without fragmentation processes.
Sample solutions were introduced into the mass spectrometer
source with a syringe pump (Harvard type 55 1111: Harvard Ap-
paratus Inc., South Natick, MA, USA) with a flow rate of 5
µL·minϪ1. Calibration was performed using protonated horse my-
oglobin. Scanning was performed from m/z ϭ 500 to 8000 in 20 s,
and several scans were summed to obtain the final spectrum. ES
mass spectra at higher resolution were obtained on an LC-Tof mass
spectrometer (Micromass, Altrincham, UK).
°C under argon to
a solution of 2-bromopicoline (7; 5 g,
29.066 mmol) in tetrahydrofuran (100 mL). After 30 min, Bu3SnCl
(7.9 mL, 29.066 mmol) was added and the reaction was monitored
by TLC. The reaction was allowed to rise to room temperature and
after 30 min a saturated aqueous solution of NH4Cl was added
(100 mL). The organic layer was separated and the aqueous layer
was extracted with diethyl ether (3 ϫ 100 mL). The combined or-
ganic layers were dried (Na2SO4) and the solvent was removed un-
der low pressure. The residue was purified by chromatography on
alumina using EtOAc/hexane (1:20) as eluent to obtain a pale yel-
1
low oil (11.1 g, 78%). B.p. 144 °C (0.6 Torr). H NMR: δ ϭ 8.58
(d, J ϭ 5.0 Hz, 1 H, H6), 7.22 (s, 1 H, H3), 6.94 (d, J ϭ 5.0 Hz, 1
H, H5), 2.32 (s, 3 H, CH3), 1.70Ϫ1.05 (m, 18 H, CH2), 0.85 (t, J ϭ
7.2 Hz, 9 H, CH3). 13C NMR: δ ϭ 173.1, 150.2, 143.9, 133.4, 123.0,
29.1, 27.3, 13.7, 9.7, 8.7. EI-MS: m/z (%) ϭ 383 (5) [M ϩ 1], 326
(85) [M Ϫ Bu], 268 (45) [M Ϫ 2Bu], 212 (100) [M Ϫ 3Bu].
Samples for ESMS were prepared by mixing the corresponding li-
gand and Cu(CF3SO3)2 in a 1:1 ratio to achieve a concentration of
10Ϫ3, 10Ϫ4, 10Ϫ5, 10Ϫ6 or 10Ϫ7  in anhydrous acetonitrile and
a concentration of 10Ϫ4  in [D4]MeOH. After stirring at room
temperature for 1 min, the clear blue solution was analysed directly L [Bis(2,2Ј-bipyrid-6Ј-yl)ketone]: Toluene (20 mL) was added to a
by ESMS.
578
mixture of compound 4 (2.15 g, 5.84 mmol), the dibromo com-
Eur. J. Inorg. Chem. 2002, 573Ϫ579

High Molecular Weight CuII Coordination Polymers
FULL PAPER
cular Chemistry (Eds.: J. L. Atwood, J. E. D. Davies, D. D.
MacNicol, F. Vögtle and J.-M. Lehn), Pergamon, Oxford,
1996.
pound 6 (0.50 g, 1.46 mmol) and tetrakis(triphenylphosphane)pal-
ladium (0.34 g, 20% mol) and the resulting mixture was stirred at
110 °C under argon for 24 hours. The toluene was then evaporated
and the residue was chromatographed on silica gel eluting with
acetone/hexane (2:5). The pale yellow solid was triturated with hex-
ane to afford a white solid (0.38 g, 77%). M.p. 171Ϫ172 °C. 1H
NMR: δ ϭ 8.68 (m, 2 H, H3), 8.66 (dd, J ϭ 7.8, 1.3 Hz, 2 H, H3Ј),
8.33 (dt, J ϭ 7.9, 1.0 Hz, 2 H, H6), 8.16 (dd, J ϭ 7.6, 1.3 Hz, 2 H,
H5Ј), 8.04 (t, J ϭ 7.7 Hz, 2 H, H4Ј), 7.70 (dt, J ϭ 7.7, 1.8 Hz, 2 H,
H5), 7.30 (ddd, J ϭ 7.5, 4.8, 1.2 Hz, 2 H, H4). 13C NMR: δ ϭ
192.8, 144.4 (2C), 153.7, 149.1, 137.3, 136.9, 125.0, 124.0, 123.4,
121.4. FAB-MS: m/z (%) ϭ 339.1 (100) [M ϩ 1], 155 (7) [M Ϫ 183
(bipy)]. C21H14N4O (338.4): calcd. C 74.53, H 4.17, N 16.57; found
[2] [2a]
J.-M. Lehn, Angew. Chem. 1990, 102, 1347; Angew. Chem.
Int. Ed. Engl. 1990, 29, 1304Ϫ1319. [2b] E. C. Constable, Tetra-
[2c]
hedron 1992, 48, 10013Ϫ10069.
P. Baxter, J.-M. Lehn, A.
Decian, J. Fischer, Angew. Chem. 1993, 105, 92Ϫ96; Angew.
[2d]
Chem. Int. Ed. Engl. 1993, 32, 69Ϫ71.
J. Rojo, J.-M. Lehn,
G. Baum, D. Fenske, O. Waldmann, P. Müller, Eur. J. Inorg.
[2e]
Chem. 1999, 517Ϫ522.
A. M. Garcia, F. J. Romero-Sal-
guero, D. M. Bassani, J.-M. Lehn, G. Baum, D. Fenske, Chem.
A. M. Garcia, D. M. Bassani,
J.-M. Lehn, G. Baum, D. Fenske, Chem. Eur. J. 1999, 5,
[2f]
Eur. J. 1999, 5, 1803Ϫ1808.
1234Ϫ1238.
[3] [3a]
P. Losier, M. J. Zaworotko, Angew. Chem. Int. Ed. Engl.
˜
C 74.45, H 4.41, N 16.68. IR (KBr): ν ϭ 1686, 1581, 1430, 1320,
[3b]
1996, 35, 2779Ϫ2781.
U. Velten, M. Rehahn, Chem. Com-
1258, 1097, 992, 752, 667 cmϪ1. UV/Vis: λ (εmax) ϭ 230 (1.0),
[3c]
mun. 1996, 2639Ϫ2641.
R. Knapp, A. Schott, M. Rehahn,
Macromolecules 1996, 29, 478Ϫ480. [3d] S. R. Batten, P. jansen,
279 (0.9).
B. Moubaraki, K. S. Murray, R. Robson, Chem. Commun.
[3e]
L* [Bis(2,2Ј-bipyrid-4-methyl-6Ј-yl)ketone]: Toluene (5 mL) was ad-
ded to a mixture of compound 8 (0.17 g, 0.442 mmol), dibromo
compound 6 (0.063 g, 0.184 mmol) and tetrakis(triphenylphos-
phane)palladium (0.043 g, 20% mol) and the resulting mixture was
stirred at 110 °C under argon for 17 hours. The toluene was then
evaporated and the residue was chromatographed on silica gel elut-
ing with acetone/hexane (2:5). The pale yellow solid was triturated
with hexane to afford a white solid (0.040 g, 59%). M.p. 149Ϫ150
°C. 1H NMR: δ ϭ 8.64 (dd, J ϭ 1.2, 7.8 Hz, 2 H), 8.54 (d, J ϭ
4.7 Hz, 2 H), 8.20Ϫ8.15 (m, 4 H), 8.03 (t, J ϭ 7.8 Hz, 2 H), 7.12
(dq, J ϭ 0.6, 6.1 Hz, 2 H), 2.25 (s, 3 H). FAB-MS: m/z (%)ϭ 367.1
(100) [M ϩ 1]. C23H18N4O (366.4): calcd. C 75.39, H 4.95, N 15.29;
found C 74.3, H 4.95, N 15.5.
1998, 439Ϫ441.
F. P. Gabba¨ı, A. Schier, J. Riede, Angew.
[3f]
Chem. Int. Ed. 1998, 37, 622Ϫ624.
S.-M. Kuang, Z.-Z.
Zhang, Q.-G. Wang, T. C. W. Mark, Chem. Commun. 1998,
[3g]
581Ϫ583.
K. N. Power, T. L. Hennigar, M. J. Zaworotko,
[3h]
Chem. Commun. 1998, 595Ϫ597.
C. Kaes, M. W. Hosseini,
C. E. F. Rickard, B. W. Skelton, A. H. White, Angew. Chem.
Int. Ed. 1998, 37, 920Ϫ922.
[4] [4a]
M. Yamashita, J. B. Fenn, J. Phys. Chem. 1984, 88,
4451Ϫ4459. [4b] M. Yamashita, J. B. Fenn, J. Phys. Chem. 1984,
88, 4671Ϫ4675.
[5a] J. A. Loo, Mass Spectrom. Rev. 1997, 16, 1Ϫ23.
N. Pot-
[5]
[5b]
ier, P. Barth, D. Tritsch, J. F. Biellmann, A. Van Dorsselaer,
Eur. J. Biochem. 1997, 243, 274Ϫ282. [5c] H. Rogniaux, A. Van
Dorsselaer, P. Barth, J. F. Biellmann, J. Barbanton, M. van
Zandt, B. Chevrier, E. Howard, A. Mitschler, N. Potier, L.
Urzhumtseva, D. Moras, A. Podjarny, J. Am. Soc. Mass Spec-
trom. 1999, 10, 635Ϫ647.
Synthesis of the CuII Coordination Polymers: The CuII coordination
polymers were obtained by mixing the ligand L or L* and CuII
triflate [Cu(CF3SO3)2] in a 1:1 ratio in anhydrous acetonitrile or in
[D4]MeOH. The resulting clear blue solution was stirred at room
temperature for 1 min.
[6] [6a]
E. Leize, A. Van Dorsselaer, R. Krämer, J.-M. Lehn, J.
Chem. Soc., Chem. Commun. 1993, 990Ϫ993. [6b] K. C. Russel,
E. Leize, A. Van Dorsselaer, J.-M. Lehn, Angew. Chem. Int.
Ed. Engl. 1994, 34, 209Ϫ213. [6c] C. Garcia, J. Guyot, G. Jemi-
net, E. Leize, H. Nierengarten, A. Van Dorsselaer, Tetrahedron
[6d]
Lett. 1999, 40, 4997Ϫ5000.
E. Leize, A. Jaffrezic, A. Van
[6e]
Dorsselaer, J. of Mass Spectrometry 1996, 31, 537Ϫ544.
C.
Acknowledgments
Piguet, G. Bernardinelli, G. Hopfgartner, Chem. Rev. 1997,
H. N., E. L. and A. V. D. thank the TMR-Project EU Nr.
ERBFMRXCT980226 on Nanometer Size Metallic Complexes for
the financial support of the ESMS work. H. N. thanks the Labora-
toire P. Fabre for financial support. J. R. thanks the French
Government for a postdoctoral fellowship. Finally, the authors
thank Dr. N. Potier for the LC-Tof analysis.
97, 2005Ϫ2062.
[7]
[8]
P. Kebarle, L. Tang, Anal. Chem. 1993, 65, 972AϪ986A.
F. M. Romero, R. Ziessel, A. Dupont-Gervais, A. Van Dorsse-
laer, Chem. Commun. 1996, 551Ϫ553.
C. Bolm, M. Ewald, M. Felder, G. Schingloff, Chem. Ber. 1992,
125, 1169Ϫ1173.
[9]
[10]
J. E. Parks, B. E. Wagner, R. H. Holm, J. Organomet. Chem.
1973, 56, 53Ϫ69.
[1] [1a]
J.-M. Lehn, Supramolecular Chemistry: Concepts and Per-
Received August 24, 2001
spectives, VCH, Weinheim, 1995. [1b] Comprehensive Supramole-
[I01328]
Eur. J. Inorg. Chem. 2002, 573Ϫ579
579