New coordination polymer networks based on copper(II) hexafluoroacetylacetonate and pyridine containing building blocks: Synthesis and structural study

Article abstract of DOI:10.1039/b604591j

The interaction between copper(ii) hexafluoroacetylacetonate [Cu(hfacac)₂] and pyridine-containing building blocks with linear, angled and trigonal geometry (1-3) has led to isolation of different coordination polymers (A-D). These were studied

Full text of DOI:10.1039/b604591j

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PAPER
www.rsc.org/njc | New Journal of Chemistry
New coordination polymer networks based on copper(II)
hexafluoroacetylacetonate and pyridine containing building blocks:
synthesis and structural studyw
Silke Winter, Edwin Weber,* Lars Eriksson and Ingeborg Cso
¨
regh*b
a
a
b
Received (in Montpellier, France) 29th March 2006, Accepted 8th September 2006
First published as an Advance Article on the web 9th October 2006
DOI: 10.1039/b604591j
2
The interaction between copper(II) hexafluoroacetylacetonate [Cu(hfacac) ] and pyridine-
containing building blocks with linear, angled and trigonal geometry (1–3) has led to isolation of
different coordination polymers (A–D). These were studied by infrared spectroscopy and single-
crystal X-ray diffraction methods. The copper coordination geometry in the present complexes
can be described as a more or less distorted square bipyramid (or elongated octahedron). The
2
unsaturated Cu(hfacac) units are connected by the aromatic spacer ligand moieties 1–3 so as to
form polymeric frameworks, which are infinite either in one (A and D) or in two dimensions (C).
The polymeric ropes or sheets are held together in the crystals by relatively weak intermolecular
interactions, in which the protruding fluoro substituents of the metallic links play an active role.
The porous compound A was also studied with respect to sensing reactions for potential analysis
of selected volatile compounds. The screening shows interesting reactions of this coordination
polymer, indicating a reversible response of relatively small and polar analytes such as methanol,
ethanol and acetone, but not of water.
Introduction
bridged bidentate pyridyl and nitrile ligands are perhaps the
most commonly used donor groups in coordination poly-
1,8
mers.
One of the most important current developments in chemical
research involves the design and study of organic–inorganic
hybrid materials of coordination polymer type, composed of
However, a great problem connected with the design of
polymeric coordination compounds is the formation of a
1
metal ions and multifunctional organic ligands. In particular,
9
penetrated network architecture having very low porosity.
they may feature open frameworks, thus being zeolite-like but
having intrinsic advantages over conventional porous materi-
Moreover, channels that are initially filled with solvent mole-
cules usually lose their stability if the guest molecules are
10
2
als because of structural variety. The strong interest in this
removed. In order to meet these problems, a combination of
field is due to the promising applications in size- or shape-
selective catalysis, molecular electronics, optics, chemical sen-
3
sing and fuel storage. In this connection, some control over
1
the principles usually applicable to coordination polymers, on
the one hand, and those of dominantly organic crystal en-
11
gineering, on the other, has been used to evolve a promising
12
new approach. The aim is to get control of the properties of a
the topology and type of the supramolecular coordination
1
network can be achieved by suitable choice of organic ligand,
crystalline material via adaptation of the whole crystal topo-
logy. Therefore, aside from the metal coordination para-
meters, a profound understanding of the wide diversity of
noncovalent interactions in solid state materials, typical of
4
metal coordination preference, inorganic counter ion, sol-
5
6
7
vent and ligand-to-metal ratio. Nevertheless, the organic
ligand with its properties such as coordination activity, solu-
bility, geometry, length and orientation of the donor sites has
one of the key functions in designing defined network struc-
tures. Here, aside from carboxylate and imine functions,
13,14
crystal engineering, is required.
Considering this approach, in an unsaturated metal com-
plex containing a fluorinated organic ligand, the tendency of
the organic fluorine to be engaged in hydrogen bonding and
Fꢀ ꢀ ꢀF interactions is expected to be rather low, although the
background of these facts is currently very controversial and
a
Institut fu¨r Organische Chemie, TU Bergakademie Freiberg,
Leipziger Str. 29, D-09596 Freiberg/Sachsen, Germany. E-mail:
edwin.weber@chemie.tu-freiberg.de; Fax: +49 3731-39-31 70
Department of Structural Chemistry, Arrhenius Laboratory,
1
5
subject to discussion. Nevertheless, organic fluorine can play
16
a significant role in the design of solid materials, just because
b
Stockholm University, S-10691 Stockholm, Sweden. E-mail:
ics@struc.su.se; Fax: +46 8 163118
w Electronic supplementary information (ESI) available: Non-cova-
lent interactions in complex A (Table S1), geometric details of the
tris(pyridylethynyl)benzene ligand moieties in complexes C and D
(Table S2), non-covalent host–guest interactions in complex D (Table
S3), and non-covalent inter-chain connections in complex D (Table
S4). See DOI: 10.1039/b604591j
of its repulsive behaviour preventing potential penetration of a
1
7
network. Also, an electron-withdrawing fluoro substituent
on the organic ligand will alter the complex stability, which
may be a supporting effect in the formation of the coordina-
1
8
tion network, relating to the ‘directional bonding principle’
discussed in more detail later in this paper (synthesis of the
1
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Scheme 3 Synthesis of the tectonic units 1–3.
Results and discussion
Synthesis of the tectonic ligands
Syntheses of the ligands 1, 2 and 3 (Scheme 1) were performed,
1
9
using the method of Sonogashira as the key reaction step. In
this process a coupling reaction between a terminal alkyne and
a halogenated aromatic compound is effected. As applied to
the present task, cross-coupling reactions of 4-ethynylpyridine
with the corresponding aryl bromides were carried out to yield
the tectonic ligands 1–3, following described procedures for
2
1
0
21
and 3 (although the catalytic systems used were different,
and the characterization of the compounds is somewhat
Scheme 1 Tectonic coordinative spacer units 1–3.
incomplete), whereas ligand 2 is a completely new compound
(
Scheme 3). The key component 4-ethynylpyridine was pre-
pared by palladium(0) coupling of 4-bromopyridine hydro-
coordination polymers). Hence, a modular construction set for
assembly of desirable polymeric coordination frameworks has
been developed, comprising oligofunctional tectons of mono-
dentate pyridyl type as coordinative spacer units (Scheme 1)
and coordinatively unsaturated copper(II) hexafluoroacetyl-
2
chloride with 2-methyl-3-butyn-2-ol (MEBYNOL) followed
2
by abstraction of the protecting group with NaOH in toluene,
2
according to the literature.
2
acetonate [Cu(hfacac) ] as the connecting metallic link essen-
2
Synthesis of the coordination polymers
tial to the approach (Scheme 2).
The principal procedure used for the formation of the present
coordination polymers corresponds to the so-called ‘direc-
tional bonding approach’ which is a strategy adopted for the
construction of supramolecular compounds through coordi-
The synthesis and characterization of the respective com-
pounds, as well as crystal structures representative of the new
coordination polymers, are described; and properties of rever-
sible vapour sorption/desorption involving the new materials
are reported.
2
3
nation chemistry. It means that, in the first instance, a
coordinatively unsaturated metal complex is required in di-
recting the other ligands intended for coordination to the
appropriate place of the coordination sphere of the metal
ion. Hence, copper(II) hexafluoroacetylacetonate was selected
as the coordinatively unsaturated complex (Scheme 2). Here,
the metal centre is poorer in electrons than in normal copper
2
3
(II) acetylacetonate. According to a suggestion of Stang,
‘‘rigid highly directional multibranched monodentate ligands,
which bind to partially coordinatively unsaturated transition
metal complexes via dative bond interaction’’ should be used,
such as the tectons 1, 2 and 3 (Scheme 1). They are intended to
form bridges between the metal centres in order to create the
polymeric compounds. Here, it should be remarked that
compound 3 has proved to be very useful for the self-assembly
of discrete (i.e. nonpolymeric) polyhedral structures and nano-
Scheme 2 Desired configuration of the coordination environment of
the copper(II) ion. Only the active sites of the tectonic ligands in the
coordination sphere are shown.
2
4
sized supramolecular cages.
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the (CH) deformation vibration of the chelate ring. Moreover,
3
the valence vibration of the CF group is rather specifically
affected in the coordination polymers. While the band at 1229
ꢂ1
cm is shifted towards lower frequencies, the band at 1145
ꢂ1
cm remains fairly constant. The deformation vibration of
ꢂ1
the CF groups at 791 cm as well as the deformation of the
3
ꢂ1
chelate ring at 662 cm
are also shifted towards lower
. However, the
frequencies in comparison with Cu(hfacac)
2
Scheme 4 Coordination polymers (A–D) formed of 1–3 with
copper(II) hexafluoroacetylacetonate (M).
influence on the Cu–O bond attributed to the tectonic coordi-
nation could not be observed due to overlapping and low
intensity of the bands. Besides, in coordination polymer A, the
ꢂ1
shift of the (CRC) valence vibration at 2208 cm in the free
ligand 1 to 2197 cm in the polymeric complex is a
2
0
ꢂ1
For the synthesis of the different coordination polymers,
separate solutions of the two components, tectonic ligand and
copper(II) hexafluoroacetylacetonate, in chloroform were pre-
pared and combined by addition of the metal-complex solu-
tion to the solution of the ligand in a stoichiometric amount.
In the case of the coordination polymers A and B, a ratio
remarkable finding, which is an indication of the changed
molecular environment of the (CRC) bond. By way of
contrast, the spectrum of coordination polymer B does not
show an analogous shift.
Crystal structures
(
L : M) of 1 : 1 was used, and for C a ratio of 2 : 3 (Scheme 4).
The coordination polymers A, C and D (Scheme 4) have been
investigated using X-ray diffraction on single crystals. Com-
plex D proved to be a chloroform-containing solvate in a very
unstable form, since the crystals rapidly decomposed into
powder at room temperature when taken out of the solution.
Nevertheless, we managed to collect X-ray intensity data at
low temperature (183 K), and to solve the crystal structure of
this compound. Crystals of complex B were also obtained, but
their quality was not good enough for a single-crystal diffrac-
tion study.
The polymers A, B and C were obtained as microcrystalline
solids, which were characterized by IR spectroscopy and
elemental analysis.
2
Using ligand 3 and Cu(hfacac) in a 1 : 1 ratio yielded
solvated crystals of coordination polymer D, which are how-
ever unstable at room temperature when not immersed in the
mother liquor, due to solvent evaporation.
IR spectroscopic characterization
The successful complexation of the tectonic ligands 1–3 to
Fig. 1–6 illustrate the investigated crystal structures. Crystal
data and details of the X-ray data reduction and structure
refinement calculations are listed in Table 2. Selected geo-
metric features of the copper coordination polyhedra in A, C
and D are presented in Table 3, and Tables S1–S4 (ESIw) show
geometric features of ligand 3 in crystals C and D, as well as
the most noteworthy non-covalent interactions and inter-
molecular contact distances in the different species.
Cu(hfacac)
collected of all compounds involved [ligands 1–3, Cu(hfacac)
and the coordination polymers A, B and C] for comparison
Table 1). Obvious differences are shown by the bands that
2
was checked by IR spectroscopy. IR spectra were
2
(
come from the Cu(hfacac) unit. The valence vibration of the
2
ꢂ1
25
carbonyl group was assigned at 1647 cm in Cu(hfacac)2.
ꢂ1
This band is shifted by nearly 20 cm
towards higher
frequencies in the polymeric compounds, indicating stabiliza-
tion of the bond by formation of the new environment of the
complex unit. That is to say, the complexation of the pyridine-
containing ligands reduces the electronegativity of the metal
The Cu(II) centre ions in the present three complexes (i.e. A,
C and D) are all sixfold coordinated, each surrounded by four
oxygen and two nitrogen atoms. The O ligand atoms are
donated by two hexafluoroacetylacetonate (hfacac) groups,
and the N atoms are coming from the adjacent pyridyl rings,
which belong to the connecting (spacer) ligand moieties
(Scheme 2). The copper coordination geometry can be de-
scribed as a more or less distorted octahedron (or square
centre in the Cu(hfacac)
2
unit. Unfortunately, the bands in the
ꢂ1
region 1646–1599 cm of the polymeric complexes could not
be clearly identified because of superimposition of the aro-
matic (CQC) and the shifted (CQO) stretching frequencies of
the complex unit. The same shift tendency can be observed for
2
6
bipyramid). Two of the ligand oxygens and the two nitrogen
2
Table 1 Comparison between the IR data of Cu(hfacac) and the complex unit in the coordination polymers A, B and C
Specification
[Cu(hfacac)
2
]
Complex A
Complex B
Complex C
n(CQO)
1647 (1615)
1561 1535
1484–1468
1257
1671
1646–1599
1532–1512
1256
1669
1646–1613
1532–1509
1257
1671
1647–1601
1532–1513
1257
n(CQC) chelate ring + n(CQO)
d(CH) chelate ring
n(CQC) chelate ring
3
n(CF )
1345
1
1
229
145
807
676
594
1203
1151
791
662
577
1210
1150
794
662
577
1203
1148
792
662
578
d(CF
3
)
d(chelate ring)
(CF
d
s
3
)
1
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Fig. 1 Perspective view of a characteristic fragment of the polymeric
A complex. The unique atom positions, and four adjacent symmetry-
generated ones [N(1a), O(2a), O(3a) and C(7a)], are labelled. The
atomic displacement ellipsoids of the non-hydrogen atoms are drawn
at 30% probability level.
Fig. 3 Perspective view of the asymmetric unit of complex C. The
atomic displacement ellipsoids of the non-hydrogen atoms are drawn
at 30% probability level.
˚
atoms, coordinated by nearly equal bond lengths of B2 A
(
Table 3), define the approximately square planar coordina-
tion plane, whereas the two remaining O ligand atoms, linked
˚
via the longer Cu–O distances (B2.2–2.3 A), occupy the axial
positions, nearly at right angles to the equatorial plane. The
aromatic spacer ligand moieties 1–3 (Scheme 1) so as to form
various polymeric frameworks, as specified below. The short-
unsaturated Cu(hfacac)2 units are linked together by the
est Cu–Cu distances in the A, C and D crystals are 9.219(1),
˚
.856(2) and 8.544(2) A, respectively.
7
(
a) Coordination polymer A. In the orthorhombic crystal of
complex A, both the metallic Cu(hfacac) link and the tectonic
2
spacer unit 1 exhibit crystallographic symmetry. As a conse-
quence, the crystallographic asymmetric unit contains only
one half of the CuC H F O ꢀ C H N monomer (Fig. 1).
1
0
2
12
4
28 16
2
The two pyridyl ring planes of the spacer (1) (both planar to
˚
within 0.009 A) are centrosymmetrically related and co-planar,
and both are only slightly tilted (8.71) with respect to the
anthracene plane within the same ligand moiety (the 14
˚
anthracene C atoms are co-planar to within 0.035 A).
2
+
The Cu ion, located at the special position x, 1/4, 3/4, is
exactly at the centre of the coordination polyhedron due to the
crystal symmetry requirement, and out of the six coordinating
ligand atoms only three (one N and two O) have unique (i.e.
symmetry-independent) positions (Table 3). Moreover, the
two coordinating hexafluoroacetylacetonate groups are also
related by crystallographic symmetry due to the special loca-
tion of the copper ion. Each hfacac moiety creates a six-
membered chelate ring upon coordination to the metal ion
(
Scheme 2). The chelate rings are usually not entirely planar,
although the O–C–C–C–O atoms of the acetylacetonate moi-
ety are practically co-planar in most cases, in order to main-
2
+
tain the delocalization of the p-electrons. The Cu
ions,
however, may deviate more or less from the plane formed by
the five other ring atoms. This is the case in A, where the
slightly puckered chelate ring was found to adopt an envelope
Fig. 2 Crystal packing of complex A. (a) Packing excerpt showing the
infinite zigzag shaped polymeric chains. (b) Stereo packing illustration
with the copper coordination indicated by shaded polyhedra.
˚
conformation with the puckering parameters Q = 0.332 A,
2
7–29
y = 124.61, j = 179.21.
The best planes fitted to the two
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Fig. 5 Perspective view of the monomeric unit of the solvated
complex D. The non-hydrogen atomic displacement ellipsoids are
drawn at 30% probability level.
2
confirmed by calculations. Accordingly, in each unit cell a
9
3
˚
volume of 690 A (B16.6%) is accessible for possible solvent
inclusion. Inspection of non-covalent connections (Table S1)
shows that most of the shorter inter-chain distances are in the
range of common van der Waals’ contacts [B(rvdW1
+
˚
r
vdW2 + 0.2) A; rCvdW = 1.70, rFvdW = 1.47, and rHvdW
=
2
9,31
˚
.20 A],
1
thus suggesting relatively weak directional inter-
action forces in the observed Fꢀ ꢀ ꢀF, Cꢀ ꢀ ꢀF, (C–)Hꢀ ꢀ ꢀO and
1
6,32
(
C–)Hꢀ ꢀ ꢀF approaches
(Table S1).
Although the frequent occurrence of the fluoro substituents
in shorter inter-chain connections may also be a consequence
of the protruding position of the CF groups (Fig. 2), it seems
3
probable that the observed (C–)Hꢀ ꢀ ꢀF connections are weak
3
2,33
directional hydrogen bonds,
which in the absence of
stronger interaction forces might affect the realized packing
Fig. 4 Crystal packing of complex C. (a) Sheets showing infinite
pattern of fused hexagons. The coordination is indicated by shaded
polyhedra. (b) Packing illustration showing superposition of two
consecutive polymeric sheets.
3
arrangement decisively. Comparison with similar known
4
1
6
3
interactions involving CF groups supports this suggestion.
3
5
Worth noting is that according to our earlier experience, the
relatively low density and packing density may be an indica-
tion of the presence of directional intermolecular forces [such
as (C–)Hꢀ ꢀ ꢀO/F] in the crystal. However, the rigidity of the
inconveniently shaped polymeric zigzag chains and the pro-
truding stiff and bulky anthracene moieties may further en-
hance the difficulties of realizing a dense packing in crystal A
[Fig. 2(b)]. A comparison with a recently published related
chelate rings with common copper centre form a dihedral
angle of 65.7(1)1.
The N–Cu–N(#) coordination angle [where (#) means sym-
metry generated equivalent position] in the orthorhombic A
crystal is 92.9(2)1, which gives rise to a ‘cis’ orientation of the
linear bidentate tectonic ligands containing N(1) and N(1#),
respectively. As a consequence, the infinite polymeric chain
progresses in zigzag fashion, taking a sharp turn with a nearly
right angle at each metal ion centre [Fig. 2(a)].
2
0
crystal structure seems to support this latter suggestion.
Accordingly, infinite zigzag chains, similar to those of the
polymeric A compound, have been observed in a Zn-contain-
2
+
ing complex, in which the four-fold coordinated Zn ions are
0
Packing of the semi-rigid zigzag chains in the solid state
leads to an arrangement with relatively low density (Table 2)
and a low estimated value for the crystal packing index
connected by bidentate 1,4-bis(4 -pyridylethenyl)tetrafluoro-
2
0
benzene spacer moieties. Two linear aromatic ligands co-
ordinate to each Zn(NO metallic link in a ‘cis’ fashion, and
3 2
)
2
9,30
(
56.2%).
The packing illustration [Fig. 2(b)] gives an
the created zigzag chains realize a crystal packing arrangement
indication of empty voids in the crystal, which could be
which shows pronounced similarity to that of complex A.
1
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3
˚
3 795(6) A ] and lower crystal symmetry (triclinic P-1).
1
Solution of the structure of compound C revealed that the
crystallographic asymmetric unit is formed by nine Cu
(
hfacac) complex entities and six tris(pyridylethynyl)benzene
2
spacer moieties (Fig. 3). Seven unique copper centres
Cu(1)–Cu(7)] occupy general positions, whereas additional
[
2
+
four Cu ions [Cu(8)–Cu(11)] are located at special positions
(
each with 50% site occupation).
The copper coordination geometries can be described as
more or less distorted square bipyramids also in complex C
Table 3). However, only four polyhedra [around
(
Cu(8)–Cu(11)] exhibit crystallographic symmetry, whereas
those connected to the Cu(1)–Cu(7) metal ions do not. More-
over, the N–Cu–N coordination angles also differ in C from
the corresponding one in A (Table 3). Unlike the ‘cis’ orienta-
tion of the bis(pyridylethynyl)anthracene ligands in A, all
N–Cu–N coordination angles are nearly or exactly 1801 (Table
3
) in the triclinic C crystals, thus yielding a linear (‘trans’)
orientation for the two pyridylethynyl groups at each copper
centre [Fig. 3 and 4(a,b)]. The geometry of the different
2
symmetry-independent Cu(hfacac) complex units shows only
modest variation (Table 3). The two chelate ring planes, which
2+
are joined by a Cu ion in a special position, are co-planar
(
dihedral angle = 0.01) due to the crystallographic symmetry,
whereas those that are linked to a metal centre in a general
position are more or less tilted with respect to each other,
forming dihedral angles between 8.1(5) and 20.6(5)1. The
average inter-chelate tilt angle, calculated for seven indepen-
dent Cu(hfacac)
2
units without crystallographic symmetry, is
12.6[4.5]1 (with the root mean square [rms] dispersion around
the arithmetic average given in square brackets).
Comparison of the six unique tris(pyridylethynyl)benzene
moieties (A–F) in complex C indicates important variations in
their conformation. The three pyridyl rings in each tectonic
ligand, which are supposed to have free rotation around the
respective CRC–C ꢀ ꢀ ꢀN axis, form significantly different
Fig. 6 Crystal packing of the solvated complex D. (a) Packing excerpt
showing the infinite coordinatively polymerized chains possessing
laterally attached solvent molecules of chloroform (minor disorder
sites are omitted for clarity). (b) Stereo packing illustration with the
coordination indicated by shaded polyhedra.
py
py
dihedral angles with their central benzene ring plane in four
moieties, namely in B, C, E and F (the tilt angles vary between
4
.1 and 81.81; Table S2w). Hence, these four ligands exhibit
However, the Zn-containing crystal has somewhat lower
propeller-like shapes, which are however quite similar between
themselves. By contrast, in two cases, namely in the A and D
ligand entities (Fig. 3), the conformation is rather flat, since
the pyridyl rings deviate only slightly from co-planarity with
the benzene ring to which they are linked (the tilt angles vary
between 4.9 and 9.11; Table S2). In comparison, all tris
symmetry (monoclinic P2/c) and significantly higher density
ꢂ3
(
D
calc,X-ray = 1.77 g cm ) than complex A. These differences
may be attributed to the stiff protruding bulky anthracene
moieties, which are present in the aromatic spacer links in
complex A, but not in the Zn-containing one.
3
6
(b) Coordination polymer C. By analogy with structure A,
(pyridyl)triazine spacer units in the Cu-acetate complex
when the Cu(hfacac) units are linked together by the trifunc-
2
exhibit the very same flat conformation.
tional three-pronged tectonic ligand 3, such as in crystals of
the C complex, the polymeric framework is expected to be
infinite in two dimensions. In effect, diffraction studies of
crystal C indicated endless polymeric sheets, similar to those
observed earlier in a related complex compound with the
three-connecting 2,4,6-tri(4-pyridyl)-1,3,5-triazine spacer units
In the crystal of C, the three-branched tris(pyridylethynyl)-
benzene entities interlink the Cu(hfacac) complex units so as
2
to form infinite patterns of fused hexagons [Fig. 4(a)], just as in
the polymeric sheets in the related Cu-acetate complex crys-
3
6
tal. The nice, apparently orderly, hexagonal arrangements
have no crystallographic hexagonal symmetries, however.
Deviation from the ideal symmetry is more pronounced in
the case of the C complex, where the calculated distances
between copper ions with diagonal locations in the hexagons
3
6
between the copper acetate dimers. The crystal structures of
these two green Cu-complexes exhibit pronounced similarities,
but also notably differences. The methanol-solvated Cu-acet-
3
6
˚
vary between 32.3 and 37.8 A [Cu(8)–Cu(9) = 32.37(1),
ate complex has monoclinic (P2 /n) crystal symmetry with
1
3
V = 3724.5(9) A , whereas the crystallographic unit cell of
˚
Cu(3)–Cu(6) = 32.59(1), Cu(4)–Cu(7) = 34.700(6) and
˚
Cu(5)–Cu(11) = 37.77(1) A; Fig. 3]. Moreover, orientation
c
complex C proved to have considerably larger volume [V =
c
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Table 2 Summary of crystal data, experimental parameters and selected details of the refinement calculations for the complexes A, C and D
Compound
Complex A
Complex C
Complex D
a
Empirical formula (sum)
Empirical formula (moiety)
C
19
H
9
Cu0.5
F
6
NO
2
C
252
H
108Cu
9(CuC10
6(C27
9
F
108
N
18
O
36
C
38
H
18Cl
(CuC10
(C27
3 3 4
CuF12N O
a
0.5[(CuC10
H
2
F
12
O
4
) ꢀ
H
2
F
12
O
4
) ꢀ
H
2
F
12
O
4
) ꢀ
(
C
28
H
16
N
2
)]
H
15
N
3
)
H
15
N
3
) ꢀ (CHCl
3
)
a
Formula weight
Temperature/K
˚
Wavelength/A
429.04
295(2)
6587.42
293(2)
MoK /0.710 73
Triclinic
ꢀ
P1 (No. 2)
18.026(6)
29.133(5)
30.927(8)
63.44(2)
78.13(3)
72.37(3)
13 798(6)
2
978.44
183(2)
CuKa/1.541 78
Triclinic
ꢀ
P1 (No. 2)
9.9110(10)
13.066(2)
16.881(5)
97.810(10)
105.820(10)
96.430(10)
2058.1(7)
2
MoKa/0.710 73
Orthorhombic
Pnan (No. 52)
10.9340(10)
14.846(2)
25.624(4)
90.0
90.0
90.0
4159.4(9)
8
1.370
a
Crystal system
Space group (No.)
˚
a/A
˚
b/A
˚
c/A
a/1
b/1
g/1
3
˚
V/A
a
Z
ꢂ3
D
m/mm
F(000)
c
/g cm
1.586
0.821
1.579
3.433
ꢂ1
0.617
1716
6534
0.25 ꢃ 0.2 ꢃ 0.1
974
0.3 ꢃ 0.2 ꢃ 0.1
Crystal size/mm
Crystal colour
0.08 ꢃ 0.10 ꢃ 0.40
Brown
3.41 to 25.86
Green
1.95 to 26.00
Green
2.76 to 74.80
y range for data collection/1
Index ranges
0 r h r 12, 0 r k r 18,
ꢂ22 r h r 22, ꢂ35 r k r 35,
0 r h r 12, ꢂ16 r k r 16,
0
48 108
r l r 31
37 r l r 37
1009 003
49 747
ꢂ21 r l r 20
No. of reflections collected
No. of unique reflections
8885
8378
3941
0.068
Full-matrix LS on F
268
45
0.138
0.052
1745
0.853
R
Refinement method
int
0.094
Full-matrix LS on F
3454
497
0.221
0.072
14066
0.852
0.043
Full-matrix LS on F
692
59
0.179
0.063
6037
1.066
2
2
2
No. of parameters refined
No. of applied constraints
[for all F ]
[for F with F 4 4s(F)]
No. of F with F 4 4s(F)
S (Goodness-of-fit on F )
b
2
wR
R
2
1
2
Final shift/esd, mean/max
Final Drmax, Drmin/e A
0.000/0.000
+0.38, ꢂ0.24
The formula unit, formula weight and multiplicity (Z) refer to the crystallographic asymmetric unit. The weights of the F values were
0.000/0.001
1.03, ꢂ0.49
0.000/0.000
+0.61, ꢂ0.54
ꢂ3
˚
a
b
2
2
2
2
ꢂ1
2
2
calculated as >s (F ) + (c
for C, and 0.097 and 1.07 for D.
P) + c P] where P = (F + 2F )/3, and the constants c and c had the values 0.070 and 0.0 for A, 0.0868 and 0.0
1 2 o c 1 2
of the pyridyl ring planes in C also varies in a way that breaks
up the crystallographic symmetry. As a consequence, each
hexagon is without symmetry (i.e. asymmetric) in the latter
case, although the pattern has crystallographic inversion
chloroform together with one monomer unit (i.e.
CuC H F N O ꢀ CHCl ), although there are two unique
3
7
17 12
3
4
3
Cu centres [Cu(1) and Cu(2)] in the crystal, both located in
special positions with site occupation factors (sof’s) = 0.5
(Fig. 5). In spite of (C–)Hꢀ ꢀ ꢀN hydrogen bond interaction
from the chloroform guest to a pyridine nitrogen [N(3)] of the
complex framework (Table S3w), the solvent molecule as well
as the acceptor ring were found to exhibit static disorder. The
observed disorder may be indicative of relatively weak inter-
action forces between the connected proton donor and accep-
tor groups in the (C–)Hꢀ ꢀ ꢀN bonds. The mean values of five
possible interactions (cf. Table S3; with the rms dispersion
around the arithmetic average given in square brackets) are
2
+
symmetry, since four out of the eleven independent Cu ions
Cu(8)–Cu(11), Fig. 3] are located on crystal inversion centres.
On the other hand, the tri(pyridyl)triazine spacer moieties in
[
3
6
the Cu-acetate complex show identical flat conformations,
thus leading to crystallographic symmetry for the created
hexagonal rings in the complex framework. Yet, the endless
two-dimensional polymeric layers pack in the very same way
in both crystals, by being piled one upon the other, as shown in
Fig. 4(b). Inspection of the inter-layer interactions and pack-
ing forces in the C crystals yielded a great number of shorter
˚
˚
3.2[1] A for the Cꢀ ꢀ ꢀN distances, 2.3[2] A for the Hꢀ ꢀ ꢀN
contacts; and 153[10]1 for the C–Hꢀ ꢀ ꢀN angles [using calcu-
1
6,32,33
Fꢀ ꢀ ꢀF, Cꢀ ꢀ ꢀF and (C–)Hꢀ ꢀ ꢀF approaches,
in agreement
4
7
with the observations in the related A and D complexes (see
below, and in Tables S1 and S4). However, the observed
noteworthy symmetry-independent connections in C can
hardly be listed in a Table of acceptable size.
lated chloroform (C–)H disorder positions, without correc-
tion or normalization].
The C(23)–C(27) pyridine ring (3) may occur in either of two
partly overlapping disorder sites with the same probability [the
refined group sof’s are both 0.50(1)]. The unprimed and
˚
primed rings are planar to within 0.047 and 0.146 A, respec-
(c) Coordination polymer D. In crystals, grown from chloro-
form solution, solvent molecules were also found to be in-
cluded. The crystallographic asymmetric unit contains one
tively, and are tilted through 35.6(5)1 with respect to each
other. The included CHCl3 molecule, on the other hand,
1
814 | New J. Chem., 2006, 30, 1808–1819
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a 2+
Table 3 Selected geometric features of the Cu coordination polyhedra
c
Complex D
b
Compound
Selected bond lengths/A
Complex A
Complex C
˚
Cu–O (shorter)
Cu–N
Cu–O (longer)
Cu–O (shorter) (mean)
Cu–N (mean)
1.996(3)
2.008(3)
2.266(3)
Vary from 1.983(6) to 2.091(8)
Vary from 1.967(5) to 2.020(4)
Vary from 2.157(8) to 2.305(7)
2.04[3]
2.006[15]
2.25[4]
1.973(2)
1.999(3)
2.319(3)
1.981[11]
2.006[9]
2.311[11]
1.989(2)
2.012(3)
2.303(2)
Cu–O (longer) (mean)
Selected bond angles/1
N–Cu–N
O (shorter)–Cu–O
93.0(2)
86.9(2)
173.3(2)
Vary from 177.4(2) to 1797(2)
Vary from 177.1(3) to 179.7(3)
180.0
180.0
180.0
180.0
180.0
180.0
(
shorter)
O (longer)–Cu–O
longer)
(
N–Cu–N (mean)
O (shorter)–Cu–O
Vary from 175.5(3) to 179.8(3)
178.4[7]
(
shorter) (mean)
O (longer)–Cu–O
longer) (mean)
178.1[9]
(
1
77[2]
a
With esd’s in parentheses for individual values; with the root mean square (rms) dispersion around the arithmetic average given in square
b
brackets for the mean values; and without esd’s for the values constrained by the crystal symmetry requirement. Complex C contains eleven
unique Cu-coordination polyhedra, of which four exhibit crystallographic inversion symmetry and seven do not. In the calculation of the mean
values of the selected bond angles in the Table 3, the angles in only seven coordination polyhedra, which are not restricted by the crystallographic
symmetry requirements, were taken into account. The corresponding angles in the remaining four polyhedra [around the Cu(8)–Cu(11) centres] are
c
all 1801. Complex D contains two unique Cu-coordination polyhedra, both with crystallographic inversion symmetry.
occupies at least three disorder sites, of which two partly
overlap each other. The unprimed and primed chloroform
sites have comparable occupancies [sof parameters are 0.43(7)
and 0.41(6), respectively], whereas the third, double primed
site seems to be populated with much lower probability [sof =
Consequently, the organic connecting link in D behaves only
as bifunctional towards the metal ion, and the complex for-
mation reaction leads to infinite one-dimensional polymeric
chains [Fig. 6(a)], just as in complex A. The three pyridyl ring
planes of the spacer moiety form distinctly different dihedral
angles with the central benzene ring plane [78.1(1)1, 3.7(2) and
22.0(7), Table S2]. Worth noting is that, although each
pyridine ring may have free rotation around the
CRC–Cpyꢀ ꢀ ꢀNpy axis, the realized propeller-like conforma-
tion of ligand 3 in D resembles those observed for the related
B, C, E and F spacer units in complex C (see above, and
Table S2).
0
.16(5)]. Worth noting is that in the final difference electron
density (Dr) map some residual electron density (Dr
0
=
max
ꢂ3
˚
.61 e A ) was detected in the vicinity of the chloroform
disorder sites, thus indicating the approximate character of the
disorder model.
2
+
Both unique Cu ions in D were found to occupy special
positions, thus they are exactly at the centres of their respective
coordination polyhedra due to the crystal symmetry require-
ment. In addition, the hfacac groups that coordinate to the
same metal centre are also related by inversion symmetry.
Hence, the two hfacac chelate ring planes joined to the same
metal centre are co-planar in both cases. The chelate rings
linked to Cu(1) were found to be approximately planar (both
Inspection of the intermolecular or inter-chain contact
distances in the solvated D complex yielded an impressive
number of possible interactions [e.g. C–Hꢀ ꢀ ꢀN, C–Hꢀ ꢀ ꢀF,
1
4,16,32,37,38
C–Fꢀ ꢀ ꢀp, C–Clꢀ ꢀ ꢀp, pꢀ ꢀ ꢀp]
and various shorter con-
nections (Table S4w), thus indicating denser packing in D than
in A. A hypothetical packing coefficient, calculated by taking
into account only the polymeric framework of D without the
˚
to within 0.102 A), whereas the corresponding ones at Cu(2)
2
9,30
are slightly puckered (envelope shaped, with the puckering
7–29
chloroform guest, is 60.0%.
Accordingly, the infinite ropes
2
˚
parameters Q = 0.384 A, y = 123.11, and j = 168.91).
of complex D pack somewhat more efficiently than those of A.
The denser packing in D is probably a consequence of the
more convenient shape of both the organic connecting link
and the created polymeric chains, and also of the lower
symmetry of crystal D (triclinic), as compared to that of A
(orthorhombic). Moreover, chloroform molecules are in-
cluded in the holes of the complex D framework [Fig. 6(b)]
The N–Cu–N(#) coordination angles in D are different from
the corresponding one in A, but similar to those observed in
crystal C, i.e. the polymer with the same tris(pyridylethynyl)-
benzene bridging units between the metallic links [Table 3,
Fig. 6(a)].
Although the tectonic ligand 3 is provided with three pyridyl
N atoms in a trigonal arrangement, available for coordination
to metal centres, one pyridyl nitrogen of each ligand molecule
3
2
via (Cguest)Hꢀ ꢀ ꢀN
hydrogen bonds
[Cguestꢀ ꢀ ꢀN /
py
py
Hguestꢀ ꢀ ꢀN distances are between 3.04(1)–3.35(3)/2.13–2.52
py
3
2
˚
is engaged in a (C)–Hꢀ ꢀ ꢀN hydrogen bond interaction with
the included chloroform solvent in crystal D (Fig. 5, Table S3).
A, Cguest–Hꢀ ꢀ ꢀNpy angles range from 142 to 1681, Table S3]. In
addition, the CHCl
3
molecules seem to be involved also in
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the tectonic spacer units, and the number of their functional
groups, available for coordination to metal ions, are crucial
for the geometry of the polymeric frameworks. In one case (D)
organic solvent molecules of chloroform were found to be
included and to obstruct one of the coordination sites of the
trivalent tecton, thus giving rise to a cross between one-
dimensional coordination polymer and crystalline solvent
inclusion. The porous polymeric crystals, held together by
relatively weak interaction forces, proved to have a potential
2
b,3b
for inclusion formation and/or sensor behaviour.
The
results of the screening of volatile compounds confirm poten-
tial application of the coordination polymers as coating
3
9
material in QMB sensors.
Fig. 7 Sensor reaction of a polymer A-coated QMB sensor in three
cycles of adsorption and desorption, each during an exposure to
methanol.
Thus, using a combination of geometrically defined pyri-
dine-containing spacer-type organic ligands and coordina-
tively unsaturated Cu(II) hexafluoroacetylacetonate moieties,
with the fluoro substitution being determinant, yielded a
successful approach to the formation of new, porous metal–
organic hybrid structures. Future modifications of the organic
spacer unit from two- to three-dimensional construction are
expected to open a range of promising coordination lattices.
1
5a
(
C)–Clꢀ ꢀ ꢀp
interactions
with the host framework
ethynyl
˚
distances are between 3.219(6)–3.561(8) A,
[
Clꢀ ꢀ ꢀp
ethynyl
C–Clꢀ ꢀ ꢀp
angles range from 147(2) to 152.6(7)1, Table
ethynyl
S3]. In spite of these host–guest interactions, the included
solvent molecule was found to exhibit static disorder by
occurring at least at three different disorder sites (Fig. 5).
Worth mentioning is that the chloroform molecule seems to be
engaged in almost the same interaction modes with the
surrounding complex framework in all of its three disorder
sites. At the same time, the available space within each void is
obviously big enough to allow static disorder for a molecule of
Experimental
Equipment
Melting points were determined with a microscope hot plate
(
Dresden Analytik). IR spectra were recorded with a Nicolet
ꢂ1
13
H and C NMR spectra were obtained with a Bruker DPX
2
9
FT-IR spectrometer 510 in the 400–4000 cm spectral range.
1
chloroform size. According to the calculations, the solvent
3
molecules reside in voids of about 165 A each, and occupy a
˚
3
400 spectrometer with (CH ) Si as internal standard. Mass
3 4
˚
total of 330 A (B16%) of the unit cell volume, thus further
enhancing the crystal packing density. The estimated crystal
spectra were recorded with HP 59987A (ESI) and HP 5890
series II/MS (5989A and 5971, GC-MS) instruments. Elemen-
tal analyses were performed with a Heraeus CHN-O Rapid
elemental analyser.
2
9,30
packing index
is as high as 72.2%, and there is no residual
solvent accessible volume to be found in the solvated D crystal.
Sensor behaviour on a quartz micro balance (QMB)
In a first screening, the porous polymeric compound A was
studied with respect to the sensor reaction for potential
analysis of volatile compounds such as alcohols (methanol,
ethanol, n-propanol, isopropanol, n-butanol), ketones (acet-
one, butanone), esters (ethyl acetate, ethyl formate), hydro-
carbons (n-hexane, toluene, limonene) and water, respectively.
The screening shows interesting reactions of this coordination
polymer, indicating a reversible response of relatively small
and polar analytes. They include methanol (Fig. 7), ethanol
and acetone, but not water. These successful analyte molecules
are small enough for free mobility in the channels of the
network. The quality of the pore walls (hydrophobic and
hydrophilic sites) may explain the reaction of the mentioned
Materials
The solvents were of analytical grade and were used without
further purification. Reagents and materials were obtained
from commercial suppliers (Aldrich, Avocado, Fluka) and
were used without further purification. The coupling reactions
were carried out under argon and monitored by TLC (Merck,
silica gel 60 F254-coated plates). For column chromatography,
neutral alumina was used (Fluka, Brockmann activity I, pH
7
.0 ꢄ 0.5, particle size 0.05–0.15 mm).
Synthesis
9
,10-Dibromoanthracene, 1,5-dibromoanthracene and 1,3,5-
3
8
tribromobenzene. These were prepared by bromination of
4
anthracene,
analytes. The results support potential application of the
9
coordination polymer as coating material in QMB sensors.
0
3
substitution of bromine for chlorine in
1
,5-dichloroanthraquinone, followed by reduction to the 1,5-
4
substituted anthracene, and deamination of 2,4,6-tribromo-
1
Conclusion
4
aniline, respectively, according to the literature procedures.
2
In this paper we have described the synthesis, the spectro-
scopic characterization and the crystal structures of novel
coordination polymers based on pyridine-containing linear
or trigonal tectonic ligands and copper(II) hexafluoroacetyl-
acetonate. The complex compounds proved to form polymeric
ropes (A and D) or sheets (C). The structural characteristics of
4-Ethynylpyridine. This was obtained by a palladium-as-
sisted coupling reaction of 4-bromopyridine hydrochloride
2
2
with 2-methyl-3-butyn-2-ol (MEBYNOL), followed by alka-
line hydrolysis of the protecting group in 85%, according to
2
2
the literature description.
1
816 | New J. Chem., 2006, 30, 1808–1819
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2
,10-Bis[2-(4-pyridyl)ethynyl]anthracene (1) . A mixture of
0
ꢂ1
1
(4-monosubst. pyridine). H NMR
9
benzene), 820 cm
(400.1 MHz, CDCl
9
,10-dibromoanthracene (0.89 g, 2.6 mmol) and 4-ethynylpyr-
3
): d = 7.4 (m, 6 H, PyH), 7.8 (s, 3 H,
ArH), 8.6 ppm (m, 6 H, PyH). C NMR (100.6 MHz, CDCl3):
1
3
idine (0.6 g, 5.8 mmol) was dissolved in boiling triethylamine–
toluene (1 : 1, v/v, 50 ml). A stream of argon was bubbled
through the boiling solution for about 30 min in order to free it
from air. After cooling to room temperature, a catalyst mixture
composed of palladium(II) acetate (12.5 mg), triphenylpho-
sphane (37.5 mg) and copper(I) iodide (12.5 mg) was added,
and the solution was heated under reflux for 1 d. The solvent
was removed under reduced pressure, and the residue was stirred
with water for 2 h to extract the triethylammonium salt. The
solid was filtered and dried in vacuo. Recrystallization from
toluene yielded 61% (0.6 g) orange needles: mp 302–308 1C.
Anal. calcd C H N (380.4) ꢀ H O: C 84.40, H 4.55, N 7.03;
d = 88.3, 91.4 (CRC), 123.4, 125.5, 130.6, 135.2, 149.9 ppm.
MS (GC-MS): m/z (%) = 381 (100) [M ], 190 (8) [M ].
+
2+
General procedure for the synthesis of coordination polymers.
Separate chloroform solutions containing stoichiometric
amounts of ligand (1, 2 or 3) and copper(II) hexafluoroacetyl-
acetonate were prepared. The salt solution was slowly added
dropwise to the ligand solution, and the mixture was stirred
for 3 h at room temperature. The precipitate was collected by
filtration, washed with chloroform and dried.
28
16
2
2
Bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-cis-l-{9,10-bis
2-(4-pyridyl)ethynyl]-anthracene-N:N }copper(II) 1D coordina-
found C 84.12, H 4.33, N 7.15%. IR (KBr): n~ = 3070–3026
arom. CH), 2208 (CRC), 1618, 1589–1405 (Ar), 828 (4-
monosubst. pyridine), 811, 770 cm . H NMR (400.1 MHz,
0
[
(
ꢂ1
1
tion polymer (A). 89% yield of a red-brown microcrystalline
solid: mp 272 1C (dec.). Anal. calcd for C H CuF N O
4
858.1): C 53.19, H 2.11, N 3.26; found C 53.12, H 2.19, N
.38%. IR (KBr): n~ = 2197 (CRC), 1671 (CQO), 1646–1599
CQC, CQO, Ar), 1532–1512 (CH chelate ring), 1256 (CQC
3
CDCl
3
): d = 7.6 (m, 4 H, PyH), 7.7 (dd, J(H,H) = 6.7 Hz,
38 18
12
2
4
13
(
J(H,H) = 3.1 Hz, 4 H, ArH), 8.7 ppm (dd, 4 H, PyH).
NMR (100.6 MHz, CDCl ): d = 90.6, 99.1 (CRC), 118.2,
25.5, 127.0, 127.5, 131.2, 132.3, 150.1 ppm; MS (+ESI): m/z
C
3
3
(
1
+
2+
chelate ring), 1203, 1151 (CF
3
), 823 (4-monosubst. pyridine),
ꢂ1
(
%) = 381 (100) [M ], 191 (57) [M ].
7
91 (CF
3
), 662 (chelate ring), 577 cm (CF
3
, Ar).
1
,5-Bis[2-(4-pyridyl)ethynyl]anthracene (2). A mixture of 1,5-
dibromoanthracene (2.18 g, 6.5 mmol) and 4-ethynylpyridine
1.5 g, 14.5 mmol) was dissolved in boiling triethylamine–
toluene (1 : 1, v/v, 50 ml). Addition of catalyst [Pd(II) acetate:
1.3 mg, PPh : 108.8 mg and Cu(I)I: 31.3 mg], reaction
Bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-cis-l-{1,5-bis
2-(4-pyridyl)ethynyl]-anthracene-N:N }copper(II) 1D coordina-
0
[
(
tion polymer (B). 70% yield of a lemon-yellow–green micro-
crystalline solid: mp 288 1C (decomp.). Anal. calcd for
3
3
C
38
H
18CuF12
N
2
O
4
(858.1): C 53.19, H 2.11, N 3.26; found C
2.94, H 2.25 N 3.33%. IR (KBr): n~ = 2208 (CRC), 1669
CQO), 1646–1613 (CQC, CQO, Ar), 1532–1509 (CH che-
late ring), 1257 (CQC chelate ring), 1210, 1150 (CF ), 879
conditions and workup as above, except for the purification
of the product, which was performed by column chromato-
graphy (silica gel, ethyl acetate), yielded 45% (1.11 g) of a
5
(
brown-orange solid: mp 4360 1C. Anal. calcd for C28
H
16
N
2
3
(
9,10-positions of anthracene), 831 (4-monosubst. pyridine),
ꢂ1
(
380.4) ꢀ 0.5 H
2
O: C 86.35, H 4.40, N 7.19; found C 86.52, H
7
94 (CF ), 662 (chelate ring), 577 cm (CF , Ar).
3
4
.39, N 6.98%. IR (KBr): n~ = 3068–3020 (arom. CH), 2209
3
(
CRC), 1605, 1592–1415 (Ar), 879 (9,10-positions of anthra-
cene), 819 (4-monosubst. pyridine), 726 cm . H NMR (400.1
ꢂ1
1
trans-Hexakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-bis
0 00
3
{-l -(1,3,5-tris[2-(4-pyridyl)ethynyl]benzene-N:N :N )}tricopper(II)
3
MHz, CDCl ): d = 7.6 (m, 6 H, ArH, PyH), 7.9 (d, J(H,H) =
6
3
3
.7 Hz, 2 H, ArH), 8.2 (d, 2 H, J(H,H) = 8.2 Hz, ArH), 8.7
2D coordination polymer (C). 66% yield of a light green
powder: mp 270 1C (decomp.). Anal. calcd for
C H Cu F N O (1097.9): C 45.95, H 1.65, N 3.83; found
3
d, 4 H, J(H,H) = 5.1 Hz, PyH), 9 ppm (s, 2 H, ArH).
13
(
C
4
2
18
1.5 18
3
6
NMR (100.6 MHz, CDCl ): d = 92.1, 92.1 (CRC), 119.9,
3
C 46.07, H 1.74, N 3.84%. IR (KBr): n~ = 2218 (CRC), 1671
(CQO), 1647-1601 (CQC, CQO, Ar), 1532–1513 (CH chelate
ring), 1257 (CQC chelate ring), 1203, 1148 (CF ), 883 (1,3,5-
3
125.3, 125.6, 125.7, 130.5, 131.1, 131.4, 131. 7, 131.8, 150.0
+
ppm. MS (+ESI): m/z (%) = 381 (100) [M ].
trisubst. benzene), 829 (4-monosubst. pyridine), 792 (CF
ꢂ1
3
),
1
,3,5-Tris[2-(4-pyridyl)ethynyl]benzene (3). A mixture of
,3,5-tribromobenzene (1.03 g, 3.27 mmol) and 4-ethynylpyr-
idine (1.3 g, 12.6 mmol) was dissolved in boiling triethylamine
90 ml). A stream of argon was bubbled through the boiling
6
62 (chelate ring), 578 cm (CF
3
).
1
X-Ray crystallographic study
(
solution for about 30 min in order to free it from air. After
cooling to room temperature, a catalyst of tetrakis(triphenyl-
phosphine)palladium(0) (244 mg) was added, and the mixture
was refluxed for 3 d. The solvent was removed under reduced
pressure, and the residue was dissolved in dichloromethane.
The solution was washed with water (3 ꢃ 150 ml), dried
Single-crystals of the coordination polymers A and C, suitable
for diffraction studies, were obtained by slow diffusion at
room temperature between a chloroform–benzene or chloro-
form solution of 1 or 3, respectively, and a superposed layer of
an ethanol solution of copper(II) hexafluoroacetylacetonate.
The same approach was used also for obtaining crystals of the
chloroform-solvated coordination polymer D, containing li-
(
Na
tral Al
0.66 g) of white needles: mp 237 1C (decomp.). Anal. calcd
for C H N (381.3): C 85.02, H 3.96, N 11.02; found C 84.74,
2
SO
4
), and concentrated. Column chromatography (neu-
2
O
3
, dichloromethane–ethanol 1–2%) yielded 53%
gand 3 and Cu(hfacac)
2
in the ratio 1 : 1.
(
X-Ray intensity data for complexes A and C were collected
4
3
on a STOE IPDS (Imaging Plate Detection System) instru-
2
7
15
3
H 4.09, N 10.83%. IR (KBr): n~ = 3076 (arom. CH), 2217
CRC), 1597, 1539, 1491, 1408 (Ar), 882 (1,3,5-trisubst.
ment equipped with a rotating anode (MoKa radiation),
whereas a CAD-4 (Enraf Nonius) diffractometer and a
4
4
(
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ꢂ3
˚
conventional X-ray tube (CuKa radiation) were used for
coordination polymer D. The net intensities were corrected
hole (Drmin = ꢂ0.49 e A ) in the final Dr map were found to
˚
be located in the vicinity of a heavy atom [0.99 and 0.88 A
4
3,45
for Lorentz, polarization
and absorption effects. Numer-
from Cu(4), respectively].
4
6
ical absorption corrections were applied for complexes A
and C (transmission varied between 0.78 and 0.91, and 0.82
and 0.90, respectively). The crystals of the chloroform-con-
taining D polymer, however, were extremely unstable. Due to
practical problems in connection to the data collection, and
for lack of a second single crystal of acceptable quality, the
collected data had to be corrected by empirical methods (the
virtual transmission varied between 0.28 and 0.73).
Crystal data together with further details of data collection,
data reduction and refinement calculations are presented in
Table 2.z
Sensorial screening experiments
The quartz microbalance (QMB) sensors employed were
commercially available 10 MHz AT-cut quartz crystals (1.37
cm diameter) with gold electrodes (0.51 cm diameter) on both
sides, purchased from FOQ, Bad Rappenau, Germany. The
frequency of the vibrating crystal was measured with a uni-
versal frequency counter connected to a personal computer.
The frequency data were recorded every 10 s.
4
7
Programs of the SHELX-97 system were used for the
solution and refinement calculations of complexes A and D,
whereas the size of the problem connected with the structure of
4
7
complex C required special versions of the SHELXS and
4
7
SHELXL programs (see below). The non-hydrogen posi-
tions and possible disorder sites (e.g. in D) were refined
together with their anisotropic displacement parameters in
all cases. The partially occupied non-hydrogen positions in
D had to be refined with simple distance constraints in order to
get acceptable geometry for the disorder models (Table 2). The
hydrogen atoms were placed at positions calculated using
The coating material composed of A was prepared by drop
coating of a fine suspension of the coordination polymer in
acetone (generated with ultrasound) with a ml-syringe onto the
centre of the electrode of the crystal. The solvent was evapo-
rated in air, and the quartz crystal was stored in a desiccator
for 10 h.
The screening experiments with the coated quartz crystals
were carried out in a flow chamber at room temperature. In
order to adjust the baseline, the chamber was flushed with dry
air. Then, a stream of air saturated with the analyte solvent
was passed into the chamber. After 20 min duration of action,
the frequency shift was determined. For regeneration, the
quartz crystals were purged with dry air for 20 min, and
reused. For each solvent, the process was repeated three times
4
7
geometric evidence, and isotropic displacement parameters
were refined for them. The LS calculation indicated relatively
large mobility or disorder for the CF groups of the Cu(hfca-
3
ca) entities, particularly in complexes A and C with X-ray
2
data collected at room temperature. Accordingly, the calcu-
lated mean values for the Ueq (F) parameters are 0.24[9] in A,
2
.22[6] in C, but only 0.11[3] A in D (with the rms deviation
˚
0
given in square brackets). Since the assumed disorder of the
CF groups could not be resolved into distinct disorder sites in
(
Fig. 8). The measured values were adjusted to a standard
3
thickness of the sensor film corresponding to 10 kHz frequency
49
shift, allowing reasonable comparison of the data.
the present cases, soft distance constraints had to be applied in
the refinement of these groups in A and C (see below) (Table 2).
Crystals of the coordination polymer C (Scheme 4) proved
3
˚
to have a remarkably large unit cell of 13 795(6) A , containing
Acknowledgements
as much as 846 non-hydrogen atoms (Table 2), and exhibiting
ꢀ
relatively low symmetry (triclinic P1). The unique fragment of
This work was supported by the German Ministry of Educa-
tion and Research (BMBF-Project ‘‘Biomon’’ 02110120) and
the Fonds der Chemischen Industrie.
the infinite two-dimensional framework consists of altogether
nine Cu(hfcaca) entities, linked together by six tris(pyridyl-
2
ethynyl)benzene units (A–F) (Fig. 5). Seven copper centres
[
Cu(1)–Cu(7)] occupy general positions, whereas an additional
four [Cu(8)–Cu(11)] are located at special positions (each with
0% site occupation). Accordingly, in the course of the X-ray
References
1
(a) Comprehensive Supramolecular Chemistry, ed. G. Alberti and
T. Bein, Elsevier, Oxford, 1996, vol. 7; (b) C. J. Jones, Chem. Soc.
Rev., 1998, 27, 289–300; (c) R. W. Saalfrank and B. Demleitner, in
Transition Metals in Supramolecular Chemistry, ed. J. P. Sauvage,
Wiley-VCH, Weinheim, 1999, pp. 1–51; (d) P. J. Hagrman, D.
Hagrman and J. Zubieta, Angew. Chem., 1999, 111, 2798–2848;
5
structure analysis, 423 non-hydrogen atoms (9 Cu, 252 C, 36
O, 18 N and 108 F) had to be located and refined, thus creating
a problem of unusual size and complexity. The phase problem
4
8
was solved using the program SHELXD, and refinement of
2
the 3454 parameters against 49 747 Fobs values required
(
e) L. F. Lindoy, Angew. Chem., Int. Ed., 1999, 38, 2638–2684; (f)
L. F. Lindoy and I. M. Atkinson, Monographs in Supramolecular
Chemistry, Royal Society of Chemistry, Cambridge, UK, 2000,
vol. 7; (g) G. Swiegers and T. J. Malefetse, Chem. Rev., 2000, 100,
SHELXH, the large-memory version of the SHELXL-97
4
7
program. Moreover, the calculations indicated relatively
high mobility or disorder for a number of fluoro substituents
3
483–3537; (h) M. D. Ward, J. A. McCleverty and J. C. Jeffery,
Coord. Chem. Rev., 2001, 222, 251–272; (i) C. N. R. Rao, S.
Natarajan and R. Vaidhyanathan, Angew. Chem., 2004, 116,
1490–1521; (j) M. Ruben, Angew. Chem., Int. Ed., 2004, 43,
2
eq (max) = 0.38(1) A for F(58)], and also for a few carbon
˚
[
U
2
atoms [Ueq (max) = 0.22(1) A for C(3F1)]. In the final least-
˚
1
466–1496; (k) M. Ruben, J. Rojo, F. J. Romero-Salguero, L.
squares calculation, the CF
3
groups were refined with soft
H. Uppadine and J.-M. Lehn, Angew. Chem., 2004, 116,
3728–3747; (l) M. Ruben, J. Rojo, F. J. Romero-Salguero, L.
H. Uppadine and J.-M. Lehn, Angew. Chem., Int. Ed., 2004, 43,
distance constraints, whereas the six-membered aromatic rings
were held riding on their C(1)/N(1) atoms, respectively, in
order to maintain acceptable geometry for them. The (C)–H
3
644–3662.
4
7
atoms were included at idealized positions. Both the highest
ꢂ3
z CCDC reference numbers 290977–290979. For crystallographic data
˚
electron density peak (Drmax = 1.03 e A ) and the deepest
in CIF or other electronic format see DOI: 10.1039/b604591j
1
818 | New J. Chem., 2006, 30, 1808–1819
This journal is ꢁc the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006

View Article Online
2
3
(a) J. A. McCleverty, T. J. Meyer, M. Fujita, A. Powell and C. A.
Creutz, Comprehensive Coordination Chemistry, Elsevier, Oxford,
20 T. M. Fasina, J. C. Collings, D. P. Lydon, D. Albesa-Jove, A. S.
Batsanov, J. A. K. Howard, P. Nguyen, M. Bruce, A. J. Scott, W.
Clegg, S. W. Watt, C. Viney and T. B. Marder, J. Mater. Chem.,
2004, 14, 2395–2404.
21 (a) H. L. Anderson, C. J. Walter, A. Vidal-Ferran, R. A. Hay,
P. A. Lowden and J. K. M. Sanders, J. Chem. Soc., Perkin
Trans. 1, 1995, 2275–2279; (b) P. J. Stang, B. Olenyuk, D. C.
Muddiman and R. D. Smith, Organometallics, 1997, 16,
3094–3096.
22 (a) L. D. Ciana and A. Haim, J. Heterocycl. Chem., 1984,
21, 607–608; (b) J. G. Rodriguez, R. Martin-Villamil, F. H. Cano
and I. Fonseca, J. Chem. Soc., Perkin Trans. 1, 1997,
709–714.
23 S. Leininger, B. Olenyuk and P. J. Stang, Chem. Rev., 2000, 100,
853–908.
2004, vol. 7; (b) T. Hertzsch, J. Hulliger, E. Weber and P. Sozzani,
in Encyclopedia of Supramolecular Chemistry, ed. J. Atwood and
J. Steed, Marcel Dekker, New York, 2004, pp. 996–1005.
(a) P. R. Andres and U. Schubert, Adv. Mater., 2004, 16,
1043–1068; (b) S. Kitagawa, R. Kitaura and S. Noro, Angew.
Chem., 2004, 116, 2388–2430; (c) S. Kitagawa, R. Kitaura and S.
Noro, Angew. Chem., Int. Ed., 2004, 43, 2334–2375; (d) J. L. C.
Rowsell and O. M. Yaghi, Angew. Chem., 2005, 117, 4748–4758;
(
2
e) J. L. C. Rowsell and O. M. Yaghi, Angew. Chem., Int. Ed.,
005, 44, 4670–4679.
4
5
K. Biradha and M. Fujita, J. Incl. Phenom., 2001, 49, 201–208.
(a) M. A. Withersby, A. J. Blake, N. R. Champness, P. Hubber-
stey, W.-S. Li and M. Schro
421–2423; (b) M. A. Withersby, A. J. Blake, N. R. Champness,
P. Hubberstey, W.-S. Li and M. Schroder, Angew. Chem., Int. Ed.
¨
der, Angew. Chem., 1997, 109,
2
24 (a) C. J. Kuehl, T. Yamamoto, S. R. Seidel and P. J. Stang, Org.
Lett., 2002, 4, 913–915; (b) S.-S. Sun, J. A. Anspach and A. J.
Lees, Inorg. Chim. Acta, 2003, 351, 363–368; (c) M. Schweiger, T.
¨
Engl., 1997, 36, 2327–2329; (c) K. A. Hirsch, S. R. Wilson and J.
F. Moore, Inorg. Chem., 1997, 36, 2960–2969.
(a) M. A. Withersby, A. J. Blake, N. R. Champness, P. A. Cooke,
¨
Yamamoto, P. J. Stang, D. Blaser and R. Boese, J. Org. Chem.,
2005, 70, 4861–4864; (d) D. C. Caskey and J. Michl, J. Org.
Chem., 2005, 70, 5442–5448.
6
P. Hubberstey, W.-S. Li and M. Schro
259–2266; (b) S. Lee, D. M. Shin and Y. K. Chung, Chem.–Eur.
J., 2004, 10, 3158–3165.
¨
der, Inorg. Chem., 1999, 38,
2
25 (a) D. Gibson, B. F. G. Johnson and J. Lewis, J. Chem. Soc. A,
1970, 1, 367–369; (b) L. Zanotto, F. Benetollo, M. Natali, G.
Rosetto, P. Zanella, S. Kaciulis and A. Mezzi, Chem. Vap.
Deposition, 2004, 10, 207–213.
7
8
B. Moulton and M. J. Zaworotko, Chem. Rev., 2001, 101, 1629–1658.
(a) K. Biradha, Y. Hongo and M. Fujita, Angew. Chem., 2000,
1
12, 4001–4003; (b) K. Biradha, Y. Hongo and M. Fujita, Angew.
26 S. Winter, W. Seichter and E. Weber, Z. Anorg. Allg. Chem.,
2004, 630, 434–442.
27 D. Cremer and J. A. Pople, J. Am. Chem. Soc., 1975, 97,
1354–1367.
28 J. A. Boeyens, J. Cryst. Mol. Struct., 1978, 8, 317–320.
29 A. L. Spek, PLATON, A Multi Purpose Crystallographic Tool
(Version 111 203), 1980–2003.
30 A. I. Kitaigorodsky, Molecular Crystals and Molecules, Academic
Press, New York, 1973.
Chem., Int. Ed., 2000, 39, 3843–3845; (c) N. G. Pschirer, D. M.
Ciurtin, M. D. Smith, U. H. F. Bunz and H.-G. zur Loye, Angew.
Chem., 2002, 114, 603–605; (d) G. Pschirer, Angew. Chem., Int.
Ed., 2002, 41, 583–585; (e) Z. Xu, Y.-H. Kiang, S. Lee, E. B.
Lobkovsky and N. Emmott, J. Am. Chem. Soc., 2000, 122,
8376–8391; (f) G. K. Patra and I. Goldberg, J. Chem. Soc.,
Dalton Trans., 2002, 1051–1057.
(a) S. R. Batten and R. Robson, Angew. Chem., 1998, 110,
9
1558–1595; (b) S. R. Batten and R. Robson, Angew. Chem., Int.
Ed., 1998, 37, 1460–1494.
31 A. Bondi, J. Phys. Chem., 1964, 68, 441–451.
32 G. R. Desiraju and T. Steiner, The Weak Hydrogen Bond (IUCr
Monographs on Crystallography, vol. 9), Oxford University
Press, New York, 1999, pp. 202–209.
33 M. Nishio, in Encyclopedia of Supramolecular Chemistry, ed. J. L.
Atwood, J. W. Steed, Marcel Dekker, New York, 2004, pp.
1576–1585.
34 A. Schwarzer, W. Seichter, E. Weber, H. Stoeckli-Evans,
M. Losada and J. Hulliger, CrystEngComm, 2004, 6, 567–
572.
¨
35 I. Csoregh, M. Czugler and E. Weber, J. Phys. Org. Chem., 1993,
6, 171–178.
36 S. R. Batten, B. F. Hoskins, B. Moubaraki, K. S. Murray and R.
Robson, Chem. Commun., 2000, 1095–1096.
37 C. A. Hunter and J. K. M. Sanders, J. Am. Chem. Soc., 1990, 112,
5525–5534.
38 E. Choi, K. Park, C. Yang, H. Kim, J. Son, S. W. Lee,
Y. H. Lee, D. Min and Y. Kwon, Chem.–Eur. J., 2004, 10,
5535–5540.
1
0 (a) B. F. Abrahams, S. R. Batten, H. Hamit, B. F. Hoskins and R.
Robson, Chem. Commun., 1996, 1313–1314; (b) S. L. James, Chem.
Soc. Rev., 2003, 32, 276–288; (c) D. N. Dybtsev, H. Chun and K.
Kim, Angew. Chem., 2004, 116, 5143–5146; (d) D. N. Dybtsev, H.
Chun and K. Kim, Angew. Chem., Int. Ed., 2004, 43, 5033–5036.
1 (a) G. R. Desiraju, Crystal Engineering, The Design of Organic
Solids, Elsevier, Amsterdam, 1989; (b) G. R. Desiraju, Angew.
Chem., 1995, 107, 2541–2558; (c) G. R. Desiraju, Angew. Chem.,
Int. Ed. Engl., 1995, 34, 2311–2327; (d) Design of Organic Solids,
Topics in Current Chemistry, ed. E. Weber, Springer-Verlag,
Berlin-Heidelberg, 1998, vol. 198; (e) Crystal Design – Structure
and Function, Perspectives in Supramolecular Chemistry, ed. G. R.
Desiraju, Wiley, Chichester, 2003, vol. 7.
1
1
2 Molecular Self-Assembly—Organic Versus Inorganic Approaches,
Structure and Bonding, ed. M. Fujita, Springer-Verlag, Berlin–
Heidelberg, 2000, vol. 96.
1
1
3 D. Braga, L. Brammer and N. R. Champness, CrystEngComm,
2
005, 7, 1–19.
4 (a) J. D. Dunitz and A. Gavezzotti, Angew. Chem., 2005, 117,
796–1819; (b) J. D. Dunitz and A. Gavezzotti, Angew. Chem.,
39 (a) F. L. Dickert, H. Stathopulos and M. Reif, Adv. Mater., 1996,
8, 525–529; (b) K. Matsuura, K. Ariga, K. Endo, Y. Aoyama and
Y. Okahata, Chem.–Eur. J., 2000, 6, 1750–1756.
40 H. Gilman and A. H. Blatt, Organic Synthesis, Wiley, New York,
1941, vol. 1, pp. 207–208.
41 M. J. Brienne and J. Jaques, Bull. Soc. Chim. Fr., 1973,
190–197.
42 Jackson and Bentley, Am. Chem. J., 1892, 14, 335–336.
43 STOE & CIE GmbH, 1997 (publications 4805-014).
44 CAD-4 software, Version 5; Enraf Nonius, Delft, The Nether-
lands.
1
Int. Ed., 2005, 44, 1766–1787.
5 (a) J. D. Dunitz and R. Taylor, Chem.–Eur. J., 1997, 3, 89–98; (b)
M. D. Prasanna, T. N. Guru and Row, Cryst. Eng., 2000, 3,
1
1
35–154; (c) G. R. Desiraju and R. Partasarathy, J. Am. Chem.
Soc., 1989, 111, 8725–8726; (d) V. R. Thalladi, H.-C. Weiss, D.
Blaser, R. Boese, A. Nangia and G. R. Desiraju, J. Am. Chem.
¨
Soc., 1998, 120, 8702–8710; (e) A. R. Choudhury and T. N. Guru
Row, Cryst. Growth Des., 2004, 4, 47–52.
1
1
6 K. Reichenba
¨
cher, H. I. Su
¨
ss and J. Hulliger, Chem. Soc. Rev.,
45 A. L. Spek, HELENA, Program for Data Reduction, Utrecht
University, The Netherlands, 2003.
46 STOE & CIE GmbH, X-shape and X-red programs, 1997.
47 G. M. Sheldrick, SHELXS–97 and SHELXL–97, University of
2005, 34, 22–30.
7 (a) M. Fujita, S. Nagao, M. Iida, K. Ogata and K. Ogura, J. Am.
Chem. Soc., 1993, 115, 1574–1576; (b) K. Kasai, M. Aoyagi and M.
Fujita, J. Am. Chem. Soc., 2000, 122, 2140–2141; (c) K. Reich-
¨
enbacher, H. I. Suss, H. Stoeckli-Evans, S. Bracco, P. Sozzani, E.
Weber and J. Hulliger, New J. Chem., 2004, 28, 393–397.
8 (a) B. J. Holliday and C. A. Mirkin, Angew. Chem., 2001, 113,
2076–2098; (b) B. J. Holliday and C. A. Mirkin, Angew. Chem.,
Int. Ed., 2001, 40, 2022–2043.
9 (a) K. Sonogashira, Y. Tohda and N. Hagihara, Tetrahedron
Lett., 1975, 16, 4467–4470; (b) S. Takahashi, Y. Kuroyama, K.
Sonogashira and N. Hagihara, Synthesis, 1980, 627–630.
Go
48 G. M. Sheldrick, SHELXD, University of Go
2002.
¨
ttingen, Germany, 1997.
¨
¨
ttingen, Germany,
1
49 (a) U. Schramm, C. E. O. Roesky, S. Winter, T. Rechenbach,
P. Boeker, P. Schulze Lammers, E. Weber and J. Bargon,
Sens. Actuators, B, 1999, 57, 233–237; (b) T. Rechenbach,
U. Schramm, P. Boeker, G. Horner, C. E. O. Roesky,
J. Trepte, S. Winter, R. Pollex, J. Bargon, E. Weber and P.
Schulze Lammers, Sens. Actuators, B, 1999, 57, 255–260.
1
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