Synthesis, structure, and characterization of a new thorium-organic framework material, Th3F5[(C10H 14)(CH2CO2)2]3(NO 3)

Article abstract of DOI:10.1039/b812629a

A new three-dimensional cubic thorium-organic framework material, Th ₃F₅[(C₁₀H₁₄)(CH₂CO ₂)₂]₃(NO₃) has been synthesized under mild hydrothermal reaction conditions using Th(NO₃) ₄?6H₂O, 1,3-adamantanediacetic acid, and aqueous HF as reagents.

Full text of DOI:10.1039/b812629a

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Synthesis, structure, and characterization of a new thorium–organic
framework material, Th F [(C H )(CH CO ) ] (NO )†
3
5
10 14
2
2 2 3
3
a
b
Kang Min Ok and Dermot O’Hare*
Received 23rd July 2008, Accepted 28th August 2008
First published as an Advance Article on the web 17th September 2008
DOI: 10.1039/b812629a
A new three-dimensional cubic thorium–organic framework
fluoride material, Th
3
F
5
[(C10
H
14)(CH
2
CO
2
)
2
]
3
(NO ), which we
3
material, Th
sized under mild hydrothermal reaction conditions using
Th(NO O, 1,3-adamantanediacetic acid, and aqueous
3
F
5
[(C10
H
14)(CH
2
CO
2
)
2
]
3
(NO
3
) has been synthe-
denote TOF-3 (thorium organic framework-3).
TOF-3 has been prepared hydrothermally by using
Th(NO O, 1,3-adamantanediacetic acid, aqueous HF, N,N-
·6H
dimethylformamide (DMF), and deionized water in a Teflon
)
4
2
3
)
4
·6H
2
3
HF as reagents.
◦
26
lined 23 mL autoclave at 140 C for 24 h. The powder X-ray
diffraction pattern of the bulk sample was in good agreement with
Owing to a great deal of technologically important applications
in gas storage, selective catalysis, sensors, separation, and ion-
exchange, recently a huge number of three-dimensional metal–
27
the calculated pattern from the single-crystal structure. TOF-3
¯
crystallizes in a cubic space group Pa3 (No. 205) that reveals a new
1–7
three-dimensional thorium–organic framework structure contain-
organic compounds have been studied and reported. Although
still a number of unsolved issues such as a thermal stability
of frameworks, an easiness of exchanging or removing guest
molecules, and a proper control of the pore size are remaining,
there are no questions that metal–organic framework materials
are one of the best candidates to reveal the above mentioned
exceptional characteristics. Until now, most of the reported metal–
organic compounds have been prepared by using main group or
transition metal elements containing tetrahedral, square pyra-
midal, or octahedral coordination geometries around the metal
ing ThO
Fig. 1).
4
5
F polyhedra and 1,3-adamantanediacetate linkers (see
8–12
centres.
Recently, however, a growing number of lanthanide-
based metal–organic framework materials have been reported
13–17
as well.
Many researchers have also tried to control the
topologies and the pore sizes of the metal–organic framework
18–20
materials by introducing a variety of organic linkers.
With these
ideas in mind, we have been trying to combine both structurally
diverse metal cations and organic linkers to obtain new metal–
organic compounds with unique topologies. Among them, we
have introduced a thorium metal, since it can create a completely
new class of materials by adopting high coordination numbers of
seven, eight, and nine. The actinide-based framework materials
have been reported to have possible applications in nuclear waste
storage and nanotechnology, and there are currently few exam-
ples of metal–organic framework solids incorporating actinide
Fig. 1 ORTEP (50% probability ellipsoids) drawing of Th
3 5
F [(C10H14)-
(
CH CO (NO ). Hydrogen atoms have been removed for clarity.
2
2
)
2
]
3
3
21,22
elements.
We have recently reported a few new thorium–organic
The unique thorium atom possesses a nine-coordinate en-
vironment with four oxygen and five fluorine atoms. As can
be seen in Fig. 2, six ThO units are connected through F
23–25
framework materials synthesized by hydrothermal reactions.
Herein, we report the phase-pure synthesis, crystal structure,
and characterization of a new three-dimensional thorium–organic
4
F
5
atoms forming a thorium hexamer. In the thorium hexamer, three
thorium centres share one fluorine atoms to give an interesting
octahedral cluster. The octahedral clusters are further linked by
the 1,3-adamantanediacetate ligands through oxygen atoms.
Interestingly, one end of the bidentate acetate in the 1,3-
adamantanediacetate ligands ligates two thorium cations in the
cluster, while the other end stretches its long arm outward radially
from the centre (see Fig. 3). Finally, the other ends of the organic
linkers coordinate to two thorium cations in other octahedral
thorium clusters to produce a three-dimensional thorium–organic
a
Department of Chemistry, Chung-Ang University, Seoul, 155-756, Republic
of Korea. E-mail: kmok@cau.ac.kr; Fax: +82 2 825 4736; Tel: +82 2 820
5
197
b
Chemistry Research Laboratory, University of Oxford, Oxford, UK
OX1 3TA. E-mail: dermot.ohare@chem.ox.ac.uk; Fax: +44 1865 285131;
Tel: +44 1865 285130
†
Electronic supplementary information (ESI) available: Experimental and
calculated powder X-ray diffraction patterns, thermogravimetric analysis
diagram, and IR spectrum for Th CO (NO ). CCDC
3
F
5
[(C10
H
14)(CH
2
2
)
2
]
3
3
4
+
framework structure (see Fig. 4). The bond distances for Th –
reference number 695985. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/b812629a
4
+
O and Th –F in the ThO
4
5
F polyhedra range from 2.386(7)
5
560 | Dalton Trans., 2008, 5560–5562
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Fig.
4
3 5
Polyhedra and ball-and-stick diagram of Th F [(C10H14)-
(
CH
2
CO
2
)
2
]
3
(NO ). Note each octahedral cluster is inter-connected by
3
1
,3-adamantanediacetate ligands to form a three-dimensional thorium–or-
Fig. 2 Ball-and-stick diagram of the octahedral thorium hexamer cluster
consisting of ThO polyhedra in Th CO (NO ).
ganic framework structure.
4
F
5
3
F
5
[(C10
H
14)(CH
2
2
)
2
]
3
3
Note three thorium cations share one fluorine to form an octahedral
geometry.
carboxylate ligands could be easily assigned. Besides, subsequent
refinement with oxygen atoms for the fluorine positions results
in slightly worse final R values, which confirms our model.
The carboxylate groups of the 1,3-adamantanediacetate linkers
are bound to two different thorium cations through oxygen
atoms. The C(12)–O(1) and C(12)–O(2) lengths are 1.272(11)
˚
and 1.259(12) A, respectively. The C(14)–O(3) and C(14)–O(4)
˚
distances are 1.295(12) and 1.223(12) A, respectively, reflecting
the differences in coordination of the each oxide ligand.
The connectivity between octahedral hexamer clusters and
1
,3-adamantanediacetate linkers creates a cationic framework
containing a cavity, in which the charge balance is retained by
the residing nitrate anions. The shortest oxygen–fluorine contact
˚
between the octahedral thorium clusters are about 3.01 A taking
30
into account atomic radii from Shannon. However, the amount
of calculated void space using the CALC SOLV command in
PLATON resulted in 4.3% including nitrate anions. If the non-
31
-
framework anion NO
3
is removed, the calculated void space is
only 10.0%, which might be due to the crowded occupation of the
bulky 1,3-adamantanediacetate linkers.
The thermal behavior of TOF-3 was investigated using ther-
mogravimetric analysis. TOF-3 shows an initial weight loss of
3 5 2 2 2 3 3
Fig. 3 Wire model for the centre of Th F [(C10H14)(CH CO ) ] (NO ).
◦
5.00% between 115 and 365 C that might be attributed to the loss
Note one end of the bidentate acetate in the 1,3-adamantanediacetate
ligand is connected to two thorium cations in the cluster, while the other
end stretches outward from the centre.
of the nitrate and one fluorine from the material (calcd 4.93%).
Further work will be performed by variable temperature XRD
measurements to monitor structure as a function of temperature.
Organic 1,3-adamantanediacetate linkers are lost by further heat-
˚
˚
to 2.438(7) A and from 2.418(7) to 2.634(7) A, respectively.
28,29
◦
Bond valence calculations
the Th cation. The Th(1)–F(1)–Th(1¢) and Th(1)–F(2)–Th(1¢)
bond angles are 113.5(3) and 113.4(3)–114.4(3) , respectively. The
nearest Th–Th neighbor distances in the octahedral clusters are
resulted in a value of 3.81 for
ing to 800 C. Powder XRD measurement on the calcined material
4
+
32
revealed that TOF-3 decomposed to ThOF
2
,
which is also a
◦
◦
further good indicator of the presence of fluorine in the structure.
The infrared spectrum of TOF-3 revealed Th–O and Th–F
-
1
-1
˚
4
.0657(8) and 4.0713(8) A. The assignment of fluoride anions was
stretches at ca. 532–594 cm and at ca. 524 cm , respectively. The
CH vibrations of 1,3-adamantanediacetate group are observed
based upon bond lengths and types, which is consistent with values
2
20,21
-1
-
previously reported.
The coordinated oxygen atoms from the
around 2840–2927 cm . Vibrations attributable to the COO and
This journal is © The Royal Society of Chemistry 2008
Dalton Trans., 2008, 5560–5562 | 5561

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-
1
N=O were observed at about 1360–1570 and 1342–1523 cm ,
15 P. Mahata and S. Natarajan, Inorg. Chem., 2007, 46, 1250.
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6 T. Devic, O. David, M. Valls, M. Jerome, C. Francois and G. F e´ rey,
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33,34
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1
7 D. T. de Lill and C. L. Cahill, Cryst. Growth Des., 2007, 7, 2390.
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thorium–organic framework material by using hydrothermal
reactions with 1,3-adamantanediacetic acid as a linker. The new
compound has been also characterized by bond valence cal-
culation, infrared spectroscopy, and thermogravimetric analysis.
Additional experiments using different organic linkers to make
various frameworks are ongoing and will be reported shortly.
9 T. E. Gier and G. D. Stucky, Nature, 1991, 349, 508.
Acknowledgements
We thank the EPSRC for support.
1
0
.00 mmol), N,N-dimethylformamide (0.25 mL), aqueous HF (40%,
Notes and references
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1
2
3
4
5
6
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2
27 Crystal data: C42
H F NO15Th , crystal size 0.08 ¥ 0.08 ¥ 0.08 mm,
54 5 3
¯
˚
˚
3
space group Pa3 (No. 205) with a = b = c = 21.247(3) A, V = 9592(2) A ,
-1
◦
˚
4
Z = 8, rcalc = 2.221 g cm , 2qmax = 54.96 , l = 0.71073 A, T = 150.0(2)
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562 | Dalton Trans., 2008, 5560–5562
This journal is © The Royal Society of Chemistry 2008