CREATED USING THE RSC COMMUNICATION TEMPLATE (VER. 2.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
Communication
[JOURNAL NAME HERE] | www.rsc.org/[JOURNAL]
Templating effects in uranyl–organic frameworks with cyclohexane-1,3dicarboxylate ligands†
Pierre Thuéry
5
10
Receipt/Acceptance Data [DO NOT ALTER/DELETE THIS TEXT]
Publication data [DO NOT ALTER/DELETE THIS TEXT]
DOI: 10.1039/b000000x [DO NOT ALTER/DELETE THIS TEXT]
Reaction of uranyl ions with cyclohexane-1,3-dicarboxylic acid
(H2CHDC) in the absence of templating species gives a twodimensional framework whereas, in the presence of 15-crown-5,
a one-dimensional, ladder-like assemblage is formed, with the
templating species being held by hydrogen bonding.
50
55
15
20
25
30
35
40
45
The family of cyclohexane polycarboxylic acid ligands, with two to
six carboxylic groups, has been widely investigated in coordination
chemistry, but cyclohexane-1,4-dicarboxylic and cyclohexane1,3,5-tricarboxylic acids are the most widespread members and
only a handful of crystal structures involving cyclohexane-1,3dicarboxylate as a ligand have been reported.1 One of these
complexes contains lanthanide ions,1c but none has been reported
with actinide ions and the only uranyl complex with a cyclohexane
carboxylate derivative known to date is an octanuclear cage
obtained with a monoester derivative of the cis,trans epimer of
Kemp's triacid.2 H2CHDC is nonetheless an interesting candidate
for the synthesis of uranyl–organic frameworks (UOFs),3 for which
related ligands such as benzene,4 pyridine5 or pyrazine6
polycarboxylates have been used. In particular, the aromatic
counterpart of CHDC2–, benzene-1,3-dicarboxylate, is known to
give a one-dimensional structure.4a
Two novel UOFs with CHDC2– ligands could be obtained under
hydrothermal conditions, the first, [UO2(CHDC)(H2O)] (1), from
the reaction of uranyl trifluoromethanesulfonate and H2CHDC, and
the second, [(UO2)2(CHDC)2(H2O)3]·(15-crown-5)·H2O (2) from
the reaction of uranyl nitrate and H2CHDC in the presence of LiOH
and 15-crown-5,‡ and their crystal structures were determined.§
Macrocycles such as crown ethers have previously been used as
structure-directing agents,7 but the idea here was somewhat
different since it was hoped that a lithium–crown complex would
be present, and possibly bound to the uranyl oxo group. This did
not happen since lithium is absent from the structure, but 15-crown5 is nevertheless present in 2 as a templating species.
The asymmetric unit in 1 contains one uranyl ion and one
CHDC2– ligand (Fig. 1). The uranyl ion is chelated by one
carboxylate group, with an average U–O bond length of 2.447(17)
Å, and it is also bound to two oxygen atoms from the other, non
chelating carboxylate groups pertaining to two other molecules,
with a shorter average bond length of 2.36(3) Å. An aquo ligand
completes the coordination sphere to give the common pentagonal
bipyramidal uranium environment. The cyclohexane ring is
disordered over two positions, with the carbon atom located
between the carboxylate-bearing atoms being common to both.
CEA, IRAMIS, SCM, LCCEf, F-91191 Gif-sur-Yvette, France. E-mail:
pierre.thuery@cea.fr
† CCDC reference numbers. For crystallographic data in CIF or other
electronic format see DOI:
This journal © Royal Society of Chemistry
60
65
These two positions correspond to two rings in the chair
conformation, with the two substituents in equatorial position (cis
isomer). However, mixing these two positions, which are related to
one another by a mirror plane of pseudo-symmetry, could also give
two distorted forms of the trans isomer, which would be in keeping
with the use of a mixture of the two isomers as starting material.
The two carboxylate groups make a dihedral angle of 61.8(11)°.
Fig. 1 View of complex 1. Displacement ellipsoids are drawn at the 30%
probability level. Symmetry codes: ' = 1 – x, 1 – y, –z; " = x + 1, 1.5 – y, z
+ 1/2; "' = x – 1, 1.5 – y, z – 1/2. Only one position of the disordered
atoms is represented. Selected bond lengths (Å) and angles (°): U–O1
1.744(6), U–O2 1.755(6), U–O3 2.464(6), U–O4 2.429(7), U–O5'
2.394(6), U–O6" 2.332(6), U–O7 2.404(6), O1–U–O2 177.6(3), O3–U–
O4 53.0(2), O4–U–O5' 72.0(2), O5'–U–O7 77.6(2), O7–U–O6" 81.6(2),
O6"–U–O3 75.8(2).
70
Fig. 2 The two-dimensional assemblage in 1 viewed down the c axis. The
uranium coordination polyhedra are represented and the other atoms are
shown as spheres of arbitrary radii. Hydrogen bonds are shown as dotted
lines. Hydrogen atoms are omitted. Only one position of the disordered
atoms is represented.
75
Each uranyl ion is bound to three CHDC2– molecules and each
ligand in its turn connects three cations, one in chelating bidentate
and two in monodentate (syn/anti) fashion. Such a coordination
[JOURNAL], 200X, 00, 0000 | 1
CREATED USING THE RSC COMMUNICATION TEMPLATE (VER. 2.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
Communication
80
85
90
95
www.rsc.org/[JOURNAL] | [JOURNAL NAME HERE]
mode of CHDC2– is found in some Mn(II), Cd(II) and Pb(II)
complexes, with however further bridging of two metal centres by
one or two oxygen atoms,1a,d while the doubly chelating mode (also
with extra bridging) is observed with Eu(III), Cd(II) and Pb(II).1 A
two-dimensional framework parallel to the (1 0 –2) plane is formed
in 1 (Fig. 2), which is built from a tessellation of two kinds of rings.
The smallest rings comprise two cations and two ligands, with the
cyclohexane rings directed outwards, whereas the largest are built
from four cations, two ligands with the cyclohexane rings directed
inwards and two bridging carboxylate groups. Two hydrogen bonds
between aquo ligands and carboxylate groups span the latter rings,
and other hydrogen bonds link successive layers. With a packing
index of 0.72 (estimation with PLATON8), compound 1 does not
contain channels of significant size.
The asymmetric unit in 2 contains two uranyl ions, two CHDC2–
and three aquo ligands, one 15-crown-5 and one water molecules
(Fig. 3). Atom U1 is chelated by three carboxylate groups
pertaining to three ligands, with an average U–O bond length of
2.459(16) Å and an hexagonal bipyramidal environment geometry.
Atom U2 is in a pentagonal bipyramidal environment, being bound
to two monodentate carboxylate groups from two ligands and to the
three aquo ligands, with unremarkable average bond lengths of
2.330(5) and 2.44(4) Å, respectively.
that observed in 1, make an angle of 24.9(8)°. Both ligands are in
the chair conformation.
125
130
135
100
105
110
115
120
Fig. 3 View of complex 2. Displacement ellipsoids are drawn at the 20%
probability level. Symmetry codes: ' = x + 1, y, z; " = 1 – x, 1 – y, 1 – z.
Selected bond lengths (Å) and angles (°): U1–O1 1.759(6), U1–O2
1.762(6), U1–O5 2.455(5), U1–O6 2.449(5), U1–O7' 2.480(6), U1–O8'
2.436(6), U1–O9 2.481(5), U1–O10 2.455(5), U2–O3 1.754(5), U2–O4
1.755(5), U2–O11 2.335(5), U2–O12" 2.325(5), U2–O13 2.449(5), U2–
O14 2.392(5), U2–O15 2.484(5), O1–U1–O2 179.2(3), O5–U1–O6
52.86(18), O6–U1–O9 67.23(18), O9–U1–O10 52.92(18), O10–U1–O7'
67.69(19), O7'–U1–O8' 52.8(2), O8'–U1–O5 66.67(19), O3–U2–O4
176.4(2), O11–U2–O12" 75.88(19), O12"–U2–O15 69.57(19), O15–U2–
O14 67.44(19), O14–U2–O13 72.23(18), O13–U2–O11 75.11(18).
Both the cis and trans isomers of CHDC2– are present in 2, the
former with the two carboxylate groups (O5, O6 and O7, O8) in
equatorial position and the second with these groups (O9, O10 and
O11, O12) in equatorial and axial position, respectively. The two
COO– coordination sites of the first, bis-bidentate ligand, which
connects U1 and its symmetry equivalents, are nearly coplanar,
with a dihedral angle of 2.3(11)°, while those of the second ligand,
bridging U1 and two U2 atoms with a coordination mode similar to
2 | [JOURNAL], 200X, 00, 0000
140
145
150
155
Fig. 4 View of the ladder-like assemblage in 2 viewed down the c axis,
with crown ethers omitted (top); view with the ladders end-on including
the hydrogen bonded crown ethers (bottom). The coordination polyhedra
of uranium are shown in yellow (U1) or green (U2), and the other atoms
are shown as spheres of arbitrary radii. Hydrogen bonds are shown as
dotted lines. Uncoordinated water molecules and hydrogen atoms are
omitted.
The assemblage in 2 is one-dimensional and assumes the shape
of a ladder-like ribbon running along the a axis (Fig. 4). The stiles
correspond to the rectilinear chains containing U1 atoms linked by
the ligands in the cis form and the slightly oblique rungs to the
dimers containing two U2 atoms and two trans ligands held
between two stiles by coordination of O9 and O10 to U1.
Elongated rings containing eight cations and six ligands are thus
formed, with a largest dimension of about 19 Å, but a quite
negligible width. When viewed end-on down the a axis,
neighbouring ribbons are tilted with respect to one another, the
sides of each pointing approximately towards the main axis of two
others. This arrangement alone gives a packing index of 0.47, and it
leaves large channels (about 15 × 4 Å2 in section) between the
ribbons which are occupied by the 15-crown-5 molecules, giving a
final packing index of 0.70. The crown ethers, in a quite irregular
conformation, are held by three hydrogen bonds with two aquo
ligands, all of these bonds being on the same side of the crown
ether loop. Other hydrogen bonds link ribbons to one another and
to the uncoordinated water molecules, while two intra-ribbon
hydrogen bonds are associated with each rung. This ladder-like
arrangement is quite close to that in the uranyl complex with
benzene-1,3-dicarboxylate, in which the dimers of U2 atoms are
however replaced by a single uranyl ion doubly chelated by the two
ligands in the rung.4a In this case, protonated dimethylformamide
This journal © Royal Society of Chemistry
CREATED USING THE RSC COMMUNICATION TEMPLATE (VER. 2.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
Communication
[JOURNAL NAME HERE] | www.rsc.org/[JOURNAL]
160
165
170
175
180
185
190
195
200
205
210
215
220
molecules are present in the lattice and the counterpart of complex
1, with no extra species included, has not been reported. This
similarity between these two uranyl complexes is at variance with
the different arrangements obtained with these two ligands in the
case of Eu(III).1c
Templating effects are well known in uranium inorganic
species.9 Among f-block metal–organic frameworks, they have
been investigated with lanthanides,10 but are less documented in the
case of uranyl ions.11 The structures of compounds 1 and 2
evidence the spectacular structure-directing effect of 15-crown-5 in
the uranyl/CHDC2– system, which turns a two-dimensional, gridlike architecture into a one-dimensional, ladder-like one, with
tilting between the subunits. It may be noted that structure-directing
crown ethers are often present as cation complexes,7a,b whereas 15crown-5 is uncomplexed in 2 (in spite of the presence of suitable
Li+ cations). Besides, the absence of any direct uranyl–crown ether
bonding is unsurprising, since such coordination is only observed
in the complete absence of other more strongly coordinating
species (and water).12 In this respect, crown ethers are more
suitable structure-directing agents for UOFs than, for example, 4,4'bipyridine, which may coordinate to uranyl ions3,13 (although it
may act as a structure-directing agent in lanthanide–organic
species10b as well as in some UOFs11a). It may be noted that
compound 2 comprises three coordinated and one free water
molecules, whereas 1 contains only one coordinated. This higher
water content in 2 may be promoted by the propensity of crown
ethers to accept hydrogen bonds and their resulting hydrophilic
nature.
In conclusion, this work provides the first examples of UOFs
with a ligand in the cyclohexane polycarboxylate family and also a
novel case of structure-directing effects in UOFs, effected by
neutral crown ether molecules.
225
displacement parameters. The cyclohexane ring in 1 is disordered over
two positions sharing one of the carbon atoms. The hydrogen atoms
bound to oxygen atoms were found on Fourier-difference maps and the
carbon-bound hydrogen atoms were introduced at calculated positions.
The drawings were done with SHELXTL15 and Balls & Sticks.16
1
230
2
235
3
4
240
5
245
6
250
7
255
8
9
260
Notes and references
‡ Synthesis of 1. H2CHDC (25 mg, 0.145 mmol), UO2(CF3SO3)2 (165 mg,
0.290 mmol) and demineralized water (3 mL) were placed in a 15 mL
tightly closed glass vessel and heated at 180 °C under autogenous
pressure (ca. 1.1 MPa), yielding light yellow crystals of complex 1 within
four days (35 mg, 53% yield on the basis of the acid). Anal. calcd for
C8H12O7U: C, 20.97; H, 2.64. Found: C, 20.82; H, 2.77%. The same
compound was obtained when a twofold excess of UO2SO4·3.5H2O was
used instead of uranyl triflate and a fourfold excess of NaOH was added.
Synthesis of 2. H2CHDC (17 mg, 0.099 mmol), UO2(NO3)2·6H2O (100
mg, 0.199 mmol), LiOH·H2O (9 mg, 0.214 mmol), 15-crown-5 (44 mg,
0.200 mmol) and demineralized water (2.2 mL) were placed in a 15 mL
tightly closed glass vessel and heated at 180 °C under autogenous
pressure (ca. 1.1 MPa), yielding light yellow crystals of complex 2 within
four days (14 mg, 24% yield on the basis of the acid). Anal. calcd for
C26H48O21U2: C, 26.63; H, 4.13. Found: C, 26.90; H, 4.17%.
§ Crystal data for 1: C8H12O7U, M = 458.21, monoclinic, space group
P21/c, a = 10.6261(6), b = 10.3755(4), c = 10.9553(5) Å,  = 113.786(3)°,
V = 1105.24(9) Å3, Z = 4, T = 100(2) K. Refinement of 192 parameters on
2095 independent reflections out of 31301 measured reflections (Rint =
0.046) led to R1 = 0.038, wR2 = 0.100, S = 1.007, min = –1.97, max =
1.35 e Å–3. Crystal data for 2: C26H48O21U2, M = 1172.70, monoclinic,
space group P21/c, a = 9.9445(3), b = 22.9894(9), c = 15.6684(7) Å,  =
93.096(3)°, V = 3576.9(2) Å3, Z = 4, T = 100(2) K. Refinement of 442
parameters on 6764 independent reflections out of 118808 measured
reflections (Rint = 0.028) led to R1 = 0.038, wR2 = 0.097, S = 1.077, min
= –1.44, max = 1.94 e Å–3. Data were collected on a Nonius Kappa-CCD
area-detector diffractometer and processed with HKL2000.14 Absorption
effects were corrected with SCALEPACK.14 The structures were solved
by direct methods and refined by full-matrix least-squares on F2 with
SHELXTL.15 All non-hydrogen atoms were refined with anisotropic
This journal © Royal Society of Chemistry
265
270
10
11
275
12
13
280
14
15
16
(a) A. Thirumurugan, M. B. Avinash and C. N. R. Rao, Dalton
Trans., 2006, 221; (b) K. P. Rao, A. Thirumurugan and C. N. R.
Rao, Chem.–Eur. J., 2007, 13, 3193; (c) S. Surblé, C. Serre, F.
Millange, F. Pellé and G. Férey, Solid State Sci., 2007, 9, 131; (d)
A. Thirumurugan, R. A. Sanguramath and C. N. R. Rao, Inorg.
Chem., 2008, 47, 823.
P. Thuéry, M. Nierlich, B. W. Baldwin, N. Komatsuzaki and T.
Hirose, J. Chem. Soc., Dalton Trans., 1999, 1047.
C. L. Cahill, D. T. de Lill and M. Frisch, CrystEngComm, 2007, 9,
15.
(a) J. Y. Kim, A. J. Norquist and D. O'Hare, Dalton Trans., 2003,
2813; (b) L. A. Borkowski and C. L. Cahill, Acta Crystallogr., Sect.
E, 2004, 60, m198; (c) Z. T. Yu, Z. L. Liao, Y. S. Jiang, G. H. Li
and J. S. Chen, Chem. Eur. J., 2005, 11, 2642; (d) Y. S. Jiang, Z. T.
Yu, Z. L. Liao, G. H. Li and J. S. Chen, Polyhedron, 2006, 25,
1359.
See, for example: (a) B. Masci and P. Thuéry, Polyhedron, 2005,
24, 229 and references therein; (b) J. M. Harrowfield, N. Lugan, G.
H. Shahverdizadeh, A. A. Soudi and P. Thuéry, Eur. J. Inorg.
Chem., 2006, 389; (c) Y. S. Jiang, G. H. Li, Y. Tian, Z. L. Liao and
J. S. Chen, Inorg. Chem. Commun., 2006, 9, 595; (d) M. Frisch and
C. L. Cahill, Dalton Trans., 2006, 4679.
(a) B. Masci and P. Thuéry, Cryst. Growth Des., 2008, 8, 1689; (b)
B. Masci and P. Thuéry, CrystEngComm, 2008, 10, 1082.
(a) P. A. Wright, R. E. Morris and P. S. Wheatley, Dalton Trans.,
2007, 5359; (b) E. V. Alekseev, S. V. Krivovichev and W.
Depmeier, Angew. Chem. Int. Ed., 2008, 47, 549; (c) M. S. Fonari,
V. C. Kravtsov, Y. A. Simonov, S. S. Basok, E. V. Ganin, V. O.
Gelmboldt, K. Suwinska, J. Lipkowski, O. A. Alekseeva and N. G.
Furmanova, Polyhedron, 2008, 27, 2049.
A. L. Spek, J. Appl. Cryst., 2003, 36, 7.
See, for example: (a) R. J. Francis, P. S. Halasyamani and D.
O'Hare, Chem. Mater., 1998, 10, 3131; (b) P. S. Halasyamani, R. J.
Francis, S. M. Walker and D. O'Hare, Inorg. Chem., 1999, 38, 271;
(c) S. M. Walker, P. S. Halasyamani, S. Allen and D. O'Hare, J. Am.
Chem. Soc., 1999, 121, 10513; (d) P. M. Almond, L. Deakin, A.
Mar and T. E. Albrecht-Schmitt, Inorg. Chem., 2001, 40, 886; (e) C.
L. Cahill and P. C. Burns, Inorg. Chem., 2001, 40, 1347; (f) J. A.
Danis, W. H. Runde, B. Scott, J. Fettinger and B. Eichhorn, Chem.
Commun., 2001, 2378; (g) A. J. Norquist, P. M. Thomas, M. B.
Doran and D. O'Hare, Chem. Mater., 2002, 14, 5179; (h) A. J.
Norquist, M. B. Doran, P. M. Thomas and D. O'Hare, Dalton
Trans., 2003, 1168.
(a) Z. G. Sun, Y. P. Ren, L. S. Long, R. B. Huang and L. S. Zheng,
Inorg. Chem. Commun., 2002, 5, 629; (b) D. T. de Lill, N. S.
Gunning and C. L. Cahill, Inorg. Chem., 2005, 44, 258; (c) D. T. de
Lill and C. L. Cahill, Cryst. Growth Des., 2007, 7, 2390.
(a) P. Thuéry, Inorg. Chem., 2007, 46, 2307; (b) P. Thuéry,
CrystEngComm, 2008, 10, 79.
P. Thuéry, N. Keller, M. Lance, J. D. Vigner and M. Nierlich, New
J. Chem., 1995, 19, 619.
(a) L. A. Borkowski and C. L. Cahill, Crystal Growth Des., 2006, 6,
2248; (b) P. Thuéry, Acta Crystallogr., Section C, 2007, 63, m54.
Z. Otwinowski and W. Minor, Methods Enzymol., 1997, 276, 307.
G. M. Sheldrick, Acta Crystallogr., Section A, 2008, 64, 112.
T. C. Ozawa and S. J. Kang, J. Appl. Cryst., 2004, 37, 679.
[JOURNAL], 200X, 00, 0000 | 3
CREATED USING THE RSC COMMUNICATION TEMPLATE (VER. 2.0) - SEE WWW.RSC.ORG/ELECTRONICFILES FOR DETAILS
Communication
www.rsc.org/[JOURNAL] | [JOURNAL NAME HERE]
Graphical Abstract:
285
Depending upon the presence of 15-crown-5 as a templating species, uranyl coordination by cyclohexane-1,3-dicarboxylate gives
either a two-dimensional, grid-like assemblage or a one-dimensional, ladder-like polymer with hydrogen bonded crown ether
molecules filling the channels.
4 | [JOURNAL], 200X, 00, 0000
This journal © Royal Society of Chemistry