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New lanthanide based coordination polymers with high potential porosity
Journal of Alloys and Compounds 451 (2008) 377–383
New lanthanide based coordination polymers with high potential porosity N. Kerbellec a , C. Daiguebonne a,∗ , K. Bernot a , O. Guillou a , X. Le Guillou b a
Sciences Chimiques de Rennes, Equipe “Mat´eriaux Inorganiques: Chimie Douce et R´eactivit´e” UMR CNRS-INSA 6226, INSA, 20 Avenue des buttes de C¨oesmes, 35043 Rennes, France b IRISA, 263 Avenue du g´ en´eral Leclerc, 35042 Rennes, France Available online 19 April 2007
Abstract Reaction in an aqueous gel medium between a lanthanide ion and the sodium salt of the naphthalene-tetra-carboxylic acid can lead to coordination polymers. We report here the synthesis, the crystal structure and the calculated porosity of the first two new coordination polymers, namely Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O and Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O. The first compound crystallizes in the triclinic system, ˚ b = 12.0131(3) A, ˚ c = 16.4256(4) A, ˚ α = 107.8706(9)◦ , β = 97.0735(9)◦ , γ = 93.4771(15)◦ and Z = 2. space group P 1¯ (no. 2) with a = 6.4456(1) A, The crystal structure can be described as wavy planes strongly connected to each other by hydrogen bonds. This pseudo 3D crystal structure presents very large rectangular channels filled by crystallization water molecules. The second compound crystallizes in the monoclinic system, ˚ b = 29.2288(2) A, ˚ c = 10.8795(1) A, ˚ β = 92.1767(3)◦ and Z = 4. Its crystal structure is 3D and space group P21 /c (no. 14) with a = 9.8442(1) A, presents some large channels with rectangular sections. These channels are full of crystallization water molecules. In both cases, the crystallization water molecules have been formally removed and the porosity has been calculated using Connolly’s algorithm. Both present a rather high potential porosity. © 2007 Elsevier B.V. All rights reserved. Keywords: Rare earth alloys and compounds; Inorganic materials; Crystal growth; Crystal structure
1. Introduction For a few years, lanthanide-based coordination polymers have deserved a special attention due to their ability to combine specific physical properties and original crystal structures. There is currently a renewed interest in that field because of the nano-technologies emergence. Actually the design of nanoporous open frameworks is a factor of this revival [1–4] because these compounds are anticipated to exhibit good efficiency as far as size selective separation, catalysis and gas storage are concerned [5,6]. These potential applications require materials that do not decompose or collapse upon the removal of the guest molecules. Such materials can be obtained by using aromatic poly-carboxylate ligands. Several lanthanide-based coordination polymers involving benzene-poly-carboxylate ligand have already been described [7–11] but potentially porous materials are rather uncommon [12]. In order to increase the
∗
Corresponding author. E-mail address: [email protected] (C. Daiguebonne).
0925-8388/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2007.04.199
intermetallic distances in these materials we have undertaken the study of naphthalene-poly-carboxylate based coordination polymers [13]. The two new lanthanide-containing coordination reported below are part of this study. Both have been obtained by reacting in aqueous gel media a lanthanide chloride with the sodium salt of naphthalene-tetra-carboxylic acid (1,4,5,8-naphtalenetetracarboxylic acid) (see Scheme 1) hereafter symbolized by ntcH4 . To the best of our knowledge these two compounds are the first lanthanide based coordination polymers involving this ligand reported so far. We describe here their synthesis, their crystal structures and their estimated porosities. 2. Experimental 2.1. Synthesis 1,4,5,8-Naphtalene-tetra-carboxylic acid (ntcH4 ) was purchased from Accros Organics and used without further purification. Tetra-sodium naphtalenetetra-carboxylate salt is prepared by addition of four equivalents of sodium hydroxide to a suspension of naphtalene-tetra-carboxylic acid in de-ionized water until complete dissolution of naphtalene-tetra-carboxylic acid. Then,
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Table 1 Crystal and final structure refinement data pounds Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O
for
comand
Chemical formula
Scheme 1. ntc4− ligand. the solution is evaporated to dryness. The residue is put in suspension in ethanol, stirred and refluxed during 1 h. After filtration and drying in a desiccator, a white powder of tetra-sodium naphtalene-tetra-carboxylate is obtained. Anal. C14 H10 O8 Na4 (MW = 392 g mol−1 ) Calcd (found): C 42.8% (42.9%); H 1.0% (1.1%); O 32.7% (32.5%); Na 23.5% (23.5%). Lanthanide oxides are purchased from Aldrich and used without further purification. Both lanthanide chloride are obtained by reaction of hydrochloric acid with the corresponding lanthanide oxide. An amount of the lanthanide oxide is put in suspension in water at 50–60 ◦ C with a magnetic stirring and hydrochloric acid is added until complete dissolution of powder. Then, the solution is evaporated to dryness and the residue is dissolved in ethanol. After precipitation
System ˚ a (A) ˚ b (A) ˚ c (A) α (◦ ) β (◦ ) γ (◦ ) ˚ 3) V (A Z Formula weight (g mol−1 ) Space group (No.) Dcalcd (g cm−3 ) μ (mm−1 ) R RW
C14 H31 O21 Gd
C21 H28 O23 Er2
Triclinic 6.4456(1) 12.0131(3) 16.4256(4) 107.8706(9) 97.0735(9) 93.4771(15) 1194.74(52) 2 692.64 P 1¯ (no. 2) 1.850 2.872 3.44% 10.83%
Monoclinic 9.8442(1) 29.2288(2) 10.8795(1) – 92.1767(3) – 3128.14(6) 4 982.96 P21 /c (no. 14) 2.040 5.421 3.49% 9.53%
by addition of ether and filtration, the powder is collected, dried and stored in a desiccator. Coordination polymers were obtained by slow diffusion of de-ionized aqueous solutions of a lanthanide chloride and naphtalene-tetra-carboxylate sodium salt, through an agarose gel bridge in a U-shaped tube. Agarose was purchased
Fig. 1. Perspective view along the a-axis of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O. Crystallization water molecules have been omitted and coordination polyhedron of Gd(III) ions have been drawn.
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Fig. 2. Projection view of an extended asymmetric unit along with numbering scheme for compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O. Crystallization water molecules have been omitted for clarity.
Fig. 3. Porosity profile of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O.
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from Accros Organics and gelified according established procedures [14,15]. The gadolinium based polymer is obtained in a 0.4% agarose gel while the erbium one is obtained in a 0.5% agarose gel. After a month, colorless single crystals were obtained in both cases. C14 H31 O21 Gd (MW = 692 g mol−1 ) Anal. Calcd (found): C 24.3% (24.1%); H 4.5% (4.3%); O 48.5% (48.8%); Gd 22.7% (22.8%). C21 H28 O23 Er2 (MW = 982 g mol−1 ) Anal. Calcd (found): C 25.7% (25.4%); H 2.8% (2.7%); O 37.5% (37.4%); Er 34.0% (34.0%). The same IR spectrum is observed for both compounds. It clearly shows vibration bands characteristic of the –(O–C–O)– groups around 1560 and 1490 cm−1 confirming the presence of carboxylate groups.
2.2. X-ray crystallographic study Both crystals have been sealed in glass capillaries for X-ray single crystal data collection in order to avoid potential dehydration. Single crystals were mounted on a Nonius KappaCCD diffractometer with Mo K␣ radiation ˚ The crystal data collection were performed at room tempera(λ = 0.71073 A). ture. A crystal-to-detector distance of 25.0 mm was used and data collection strategy (determination and optimization of the detector and goniometer positions) was performed with the help of the COLLECT program [16] to measure Bragg reflections of the unique volume in reciprocal space. Unique reflections were indexed, Lorentz-polarization corrected and then integrated by the DENZO program of the KappaCCD software package [17]. Absorption corrections were performed using the facilities [18–22] included in the WinGX program suite [23]. Structure determinations were performed with the solving program SIR97 [24] that revealed all the non-hydrogen atoms. All non-hydrogen atoms were refined anisotropically using the SHELXL program [25–27]. Hydrogen atoms bound to the organic ligand were localized at ideal positions. Hydrogen atoms of water molecules have not been localized. Crystal and final structure refinement data of the two compounds are listed in Table 1. Full details of the X-ray structure determination of both compounds have been deposited with the Cambridge Crystallographic Data Center, under the depository numbers CCDC-605893 and CCDC-605892, respectively, and can be obtained, free of charge, at http://www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 IEZ, UK; fax: (internat.) +44 1223/336-033; E-mail: [email protected]].
3. Results and discussion 3.1. Crystal structure description of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O The crystal structure can be described as wavy planes spreading in the (a, −c) plane (see Fig. 1). The Gd(III) ion is coordinated by four oxygen atoms from coordination water molecules and five oxygen atoms from three different carboxylato groups, thus forming a distorded tricapped trigonal prism. There are two crystallographically independent ligand (see Fig. 2). One is binding only two Gd(III) ions via two bidentate carboxylate groups. Its two remaining carboxylate groups are protonated and do not coordinate any metallic ion. The second ligand has its four carboxylate functions bound to four different Gd(III) ions. Two out of the four are bidentate while the last two are monodentate. The wavy planes are strongly bound to each other by strong hydrogen bonds leading to a pseudo 3D molecular network. This molecular framework exhibits large channel with rectangular cross-section spreading along the a-axis (see Fig. 1). These channels are filled by crystallization water molecules.
Fig. 4. Projection view along the a-axis of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O. The coordination polyhedron of the Er(III) ions have been drawn.
In this crystal structure, the smallest intermetallic distances ˚ along the a-axis and in the molecular planes are roughly 6.44 A ˚ in the other directions. The shortest lie in the range of 10–12 A ˚ interplanes Gd–Gd distances lie between 6 and 7 A. As far as metallic centers are concerned, the channels’ section can be described as an almost perfect rectangle. The longest sides ˚ long and the smallest sides 11.8 A ˚ long. are roughly 16.5 A 3.2. Estimated porosity of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O This compound has been obtained only in gel medium and until now, despite great synthetic efforts, it has not been possible to obtain it as a microcrystalline powder. Therefore, since no measurement of its porosity was possible, we have estimated it by a computational method. We have formally partially dehydrate the compound: the crystallization water molecules (easy to remove experimentally) are formally removed while the coordination water molecules (strongly bounded to the metal ions) are not. This computational method based on Connolly’s algorithm [28] has already been described and successfully
N. Kerbellec et al. / Journal of Alloys and Compounds 451 (2008) 377–383
Fig. 5. Projection view of an extended asymmetric unit along with the numbering scheme for compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O.
Fig. 6. Porosity profile of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O.
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used elsewhere [29]. Thanks to it, the porosity of a partially dehydrated material can be calculated on the basis of its crystal structure. In order to compare the results of the calculations with experimental values, we have used a probe ˚ that is the usual kinetic sphere presenting a radius of 1.8 A radius of N2 [30]. With this value the potential specific accessible surface of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 is 522 m2 g−1 . Furthermore, this method allows to obtain the biggest kinetic radius a guest molecule can present for being hosted by the structure. As can be seen on the porosity profile (reported in Fig. 3), this compound is able to host molecules ˚ This is in perfect agreewith kinetic radii as big as 3.25 A. ment with what could be anticipated from the crystallographic data. 3.3. Crystal structure description of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O
4. Conclusions and outlook We have reported here the two first examples of lanthanide-based coordination polymers involving 1,4,5,8naphtalene-tetra-carboxylate as ligand. Both present rather high dimensionality. Thanks to Connolly’s approach we have also estimated their potential porosity. In both cases the obtained values are rather high. This confirms the validity of our approach. Up to now, these two compounds have been only obtained with Er3+ and Gd3+ ions, respectively. It would be very interesting to extend the families to other lanthanide ions exhibiting catalytic or optical properties. Furthermore, until now, they are not available for technical applications or even for further physical measurements because we have obtained them only as single crystal in gel media. We are currently working for obtaining them as microcrystalline powders. Acknowledgements
The second compound crystallizes in the monoclinic ˚ system, space group P21 /c (no. 14) with a = 9.8442(1) A, ◦ ˚ ˚ b = 29.2288(2) A, c = 10.8795(1) A, β = 92.1767(3) and Z = 4. Its crystal structure is 3D and presents some large channels with rectangular sections spreading along the a-axis (see Fig. 4). The channels are full of crystallization water molecules. There are two crystallographically independent Er(III) ions in this structure (see Fig. 5). The first one (Er1) is eight coordinated by two oxygen atoms from coordination water molecules and six oxygen atoms from four carboxylato groups (a bidentate one and three unidentate) from three different ligands. Its coordination polyhedron can be described as a slightly distorted tricapped trigonal prism. The second Er(III) ion (Er2) is eight-coordinated by eight oxygen atoms. Three out of them are oxygen atoms from coordination water molecules and the five others are belonging to four carboxylate groups from four different ligands (one bidentate and three monodentate). The coordination polyhedron is also best described by a distorted tricapped trigonal prism. There are two independent ligands in the crystal structure. One of them presents two bridging and two bidentate carboxylate functions while the other presents two bridging and two monodentate carboxylate functions. As far as metallic ions are concerned, the section of the channels can be described as a slightly distorted irregular hexagon. The two longest sides of this irregular hexagon are roughly ˚ long while the four shortest lie in the range of 4.9–5.5 A. ˚ 10.3 A 3.4. Estimated porosity of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O Once again we have not succeeded until now to obtain this compound as a microcrystalline powder. Therefore we have applied the same procedure as described above for estimating the potential porosity of this compound. Actually, ˚ we obtained a potenusing a probe sphere radius of 1.8 A tial specific accessible surface of 744 m2 g−1 for compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 . The porosity profile (Fig. 6) reveals that this compound is able to host molecules with kinetic ˚ radii as big as 2.25 A.
The authors thank the “R´egion Bretagne” for financial support. The Center of Crystallography of the “Universit´e de Rennes” is acknowledged for recording crystallographic data. References [1] O.M. Yaghi, H. Li, T.L. Groy, J. Am. Chem. Soc. 118 (1996) 9096–9101. [2] J.L.C. Rowsell, O.M. Yaghi, Micropor. Mesopor. Mater. 73 (2004) 3–14. [3] H.K. Chae, D.Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A.J. Matzger, M. O’Keeffe, O.M. Yaghi, Nature 427 (2004) 523–527. [4] F. Serpaggi, T. Luxbacher, A.K. Cheetham, G. Ferey, J. Solid State Chem. 145 (1999) 580–586. [5] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi, Science 295 (2002) 469–472. [6] S.S. Kaye, J.R. Long, J. Am. Chem. Soc. 127 (2005) 6506–6507. [7] O. Guillou, C. Daiguebonne, in: K.A. Gschneider, J.-C.G. B¨unzli, V.K. Pecharsky (Eds.), Handbook on the Physics and Chemistry of Rare Eaths, vol. 34, Elsevier, 2005, pp. 359–404. [8] C. Daiguebonne, Y. G´erault, O. Guillou, A. Lecerf, K. Boubekeur, P. Batail, M. Kahn, O. Kahn, J. Alloys Compd. 275–277 (1998) 50–53. [9] C. Daiguebonne, O. Guillou, K. Boubekeur, Inorg. Chim. Acta 304 (2000) 161–169. [10] A. Deluzet, O. Guillou, Acta Crystallogr. C 59 (2003) m277–m279. [11] O. Guillou, C. Daiguebonne, M. Camara, N. Kerbellec, Inorg. Chem. 45 (21) (2006) 8468–8470. [12] T. Devic, C. Serre, N. Audebrand, J. Marrot, G. F´erey, J. Am. Chem. Soc. 127 (2005) 12788–12789. [13] A. Deluzet, W. Maudez, C. Daiguebonne, O. Guillou, Crystal Growth Des. 3 (2003) 475–479. [14] H.K. Henisch, Crystal Growth in Gels, The Pennsylvania State University Press, 1970, pp. 1–196. [15] H.K. Henisch, Crystals in Gels and Liesegang Rings, Cambridge University Press, Cambridge, 1988. [16] nonius COLLECT, KappaCCD software, Delft, The Netherlands, 1998. [17] Z. Otwinowski, W. Minor, Methods Enzymol. (1997) 307–326. [18] N.W. Alcock, Cryst. Comput. (1970) 271. [19] W.R. Busing, H.A. Levy, Acta Crystallogr. 10 (1957) 180–182. [20] P. Coppens, L. Leiserowitz, D. Rabinovitch, Acta Crystallogr. 18 (1965) 1035–1038. [21] C. Katayama, Acta Crystallogr. A 42 (1986) 19–23. [22] R.H. Blessing, Acta Crystallogr. A 51 (1995) 33–38. [23] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837–838.
N. Kerbellec et al. / Journal of Alloys and Compounds 451 (2008) 377–383 [24] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr. 32 (1999) 115–119. [25] G.M. Sheldrick, T.R. Schneider, Macromol. Crystallogr. Part B (1997) 319–343. [26] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467–473.
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[27] G.M. Sheldrick, Acta Crystallogr. D 49 (1993) 18–23. [28] M.L. Connolly, Science 221 (1983) 709–713. [29] C. Daiguebonne, N. Kerbellec, K. Bernot, Y. G´erault, A. Deluzet, O. Guillou, Inorg. Chem. 45 (2006) 5399–5406. [30] N. Rosi, J. Kim, M. Eddaoudi, B. Chen, M. O’Keeffe, O.M. Yaghi, J. Am. Chem. Soc. 127 (2005) 1504–1518.
New lanthanide based coordination polymers with high potential porosity N. Kerbellec a , C. Daiguebonne a,∗ , K. Bernot a , O. Guillou a , X. Le Guillou b a
Sciences Chimiques de Rennes, Equipe “Mat´eriaux Inorganiques: Chimie Douce et R´eactivit´e” UMR CNRS-INSA 6226, INSA, 20 Avenue des buttes de C¨oesmes, 35043 Rennes, France b IRISA, 263 Avenue du g´ en´eral Leclerc, 35042 Rennes, France Available online 19 April 2007
Abstract Reaction in an aqueous gel medium between a lanthanide ion and the sodium salt of the naphthalene-tetra-carboxylic acid can lead to coordination polymers. We report here the synthesis, the crystal structure and the calculated porosity of the first two new coordination polymers, namely Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O and Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O. The first compound crystallizes in the triclinic system, ˚ b = 12.0131(3) A, ˚ c = 16.4256(4) A, ˚ α = 107.8706(9)◦ , β = 97.0735(9)◦ , γ = 93.4771(15)◦ and Z = 2. space group P 1¯ (no. 2) with a = 6.4456(1) A, The crystal structure can be described as wavy planes strongly connected to each other by hydrogen bonds. This pseudo 3D crystal structure presents very large rectangular channels filled by crystallization water molecules. The second compound crystallizes in the monoclinic system, ˚ b = 29.2288(2) A, ˚ c = 10.8795(1) A, ˚ β = 92.1767(3)◦ and Z = 4. Its crystal structure is 3D and space group P21 /c (no. 14) with a = 9.8442(1) A, presents some large channels with rectangular sections. These channels are full of crystallization water molecules. In both cases, the crystallization water molecules have been formally removed and the porosity has been calculated using Connolly’s algorithm. Both present a rather high potential porosity. © 2007 Elsevier B.V. All rights reserved. Keywords: Rare earth alloys and compounds; Inorganic materials; Crystal growth; Crystal structure
1. Introduction For a few years, lanthanide-based coordination polymers have deserved a special attention due to their ability to combine specific physical properties and original crystal structures. There is currently a renewed interest in that field because of the nano-technologies emergence. Actually the design of nanoporous open frameworks is a factor of this revival [1–4] because these compounds are anticipated to exhibit good efficiency as far as size selective separation, catalysis and gas storage are concerned [5,6]. These potential applications require materials that do not decompose or collapse upon the removal of the guest molecules. Such materials can be obtained by using aromatic poly-carboxylate ligands. Several lanthanide-based coordination polymers involving benzene-poly-carboxylate ligand have already been described [7–11] but potentially porous materials are rather uncommon [12]. In order to increase the
∗
Corresponding author. E-mail address: [email protected] (C. Daiguebonne).
0925-8388/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2007.04.199
intermetallic distances in these materials we have undertaken the study of naphthalene-poly-carboxylate based coordination polymers [13]. The two new lanthanide-containing coordination reported below are part of this study. Both have been obtained by reacting in aqueous gel media a lanthanide chloride with the sodium salt of naphthalene-tetra-carboxylic acid (1,4,5,8-naphtalenetetracarboxylic acid) (see Scheme 1) hereafter symbolized by ntcH4 . To the best of our knowledge these two compounds are the first lanthanide based coordination polymers involving this ligand reported so far. We describe here their synthesis, their crystal structures and their estimated porosities. 2. Experimental 2.1. Synthesis 1,4,5,8-Naphtalene-tetra-carboxylic acid (ntcH4 ) was purchased from Accros Organics and used without further purification. Tetra-sodium naphtalenetetra-carboxylate salt is prepared by addition of four equivalents of sodium hydroxide to a suspension of naphtalene-tetra-carboxylic acid in de-ionized water until complete dissolution of naphtalene-tetra-carboxylic acid. Then,
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Table 1 Crystal and final structure refinement data pounds Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O
for
comand
Chemical formula
Scheme 1. ntc4− ligand. the solution is evaporated to dryness. The residue is put in suspension in ethanol, stirred and refluxed during 1 h. After filtration and drying in a desiccator, a white powder of tetra-sodium naphtalene-tetra-carboxylate is obtained. Anal. C14 H10 O8 Na4 (MW = 392 g mol−1 ) Calcd (found): C 42.8% (42.9%); H 1.0% (1.1%); O 32.7% (32.5%); Na 23.5% (23.5%). Lanthanide oxides are purchased from Aldrich and used without further purification. Both lanthanide chloride are obtained by reaction of hydrochloric acid with the corresponding lanthanide oxide. An amount of the lanthanide oxide is put in suspension in water at 50–60 ◦ C with a magnetic stirring and hydrochloric acid is added until complete dissolution of powder. Then, the solution is evaporated to dryness and the residue is dissolved in ethanol. After precipitation
System ˚ a (A) ˚ b (A) ˚ c (A) α (◦ ) β (◦ ) γ (◦ ) ˚ 3) V (A Z Formula weight (g mol−1 ) Space group (No.) Dcalcd (g cm−3 ) μ (mm−1 ) R RW
C14 H31 O21 Gd
C21 H28 O23 Er2
Triclinic 6.4456(1) 12.0131(3) 16.4256(4) 107.8706(9) 97.0735(9) 93.4771(15) 1194.74(52) 2 692.64 P 1¯ (no. 2) 1.850 2.872 3.44% 10.83%
Monoclinic 9.8442(1) 29.2288(2) 10.8795(1) – 92.1767(3) – 3128.14(6) 4 982.96 P21 /c (no. 14) 2.040 5.421 3.49% 9.53%
by addition of ether and filtration, the powder is collected, dried and stored in a desiccator. Coordination polymers were obtained by slow diffusion of de-ionized aqueous solutions of a lanthanide chloride and naphtalene-tetra-carboxylate sodium salt, through an agarose gel bridge in a U-shaped tube. Agarose was purchased
Fig. 1. Perspective view along the a-axis of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O. Crystallization water molecules have been omitted and coordination polyhedron of Gd(III) ions have been drawn.
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Fig. 2. Projection view of an extended asymmetric unit along with numbering scheme for compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O. Crystallization water molecules have been omitted for clarity.
Fig. 3. Porosity profile of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O.
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from Accros Organics and gelified according established procedures [14,15]. The gadolinium based polymer is obtained in a 0.4% agarose gel while the erbium one is obtained in a 0.5% agarose gel. After a month, colorless single crystals were obtained in both cases. C14 H31 O21 Gd (MW = 692 g mol−1 ) Anal. Calcd (found): C 24.3% (24.1%); H 4.5% (4.3%); O 48.5% (48.8%); Gd 22.7% (22.8%). C21 H28 O23 Er2 (MW = 982 g mol−1 ) Anal. Calcd (found): C 25.7% (25.4%); H 2.8% (2.7%); O 37.5% (37.4%); Er 34.0% (34.0%). The same IR spectrum is observed for both compounds. It clearly shows vibration bands characteristic of the –(O–C–O)– groups around 1560 and 1490 cm−1 confirming the presence of carboxylate groups.
2.2. X-ray crystallographic study Both crystals have been sealed in glass capillaries for X-ray single crystal data collection in order to avoid potential dehydration. Single crystals were mounted on a Nonius KappaCCD diffractometer with Mo K␣ radiation ˚ The crystal data collection were performed at room tempera(λ = 0.71073 A). ture. A crystal-to-detector distance of 25.0 mm was used and data collection strategy (determination and optimization of the detector and goniometer positions) was performed with the help of the COLLECT program [16] to measure Bragg reflections of the unique volume in reciprocal space. Unique reflections were indexed, Lorentz-polarization corrected and then integrated by the DENZO program of the KappaCCD software package [17]. Absorption corrections were performed using the facilities [18–22] included in the WinGX program suite [23]. Structure determinations were performed with the solving program SIR97 [24] that revealed all the non-hydrogen atoms. All non-hydrogen atoms were refined anisotropically using the SHELXL program [25–27]. Hydrogen atoms bound to the organic ligand were localized at ideal positions. Hydrogen atoms of water molecules have not been localized. Crystal and final structure refinement data of the two compounds are listed in Table 1. Full details of the X-ray structure determination of both compounds have been deposited with the Cambridge Crystallographic Data Center, under the depository numbers CCDC-605893 and CCDC-605892, respectively, and can be obtained, free of charge, at http://www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 IEZ, UK; fax: (internat.) +44 1223/336-033; E-mail: [email protected]].
3. Results and discussion 3.1. Crystal structure description of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O The crystal structure can be described as wavy planes spreading in the (a, −c) plane (see Fig. 1). The Gd(III) ion is coordinated by four oxygen atoms from coordination water molecules and five oxygen atoms from three different carboxylato groups, thus forming a distorded tricapped trigonal prism. There are two crystallographically independent ligand (see Fig. 2). One is binding only two Gd(III) ions via two bidentate carboxylate groups. Its two remaining carboxylate groups are protonated and do not coordinate any metallic ion. The second ligand has its four carboxylate functions bound to four different Gd(III) ions. Two out of the four are bidentate while the last two are monodentate. The wavy planes are strongly bound to each other by strong hydrogen bonds leading to a pseudo 3D molecular network. This molecular framework exhibits large channel with rectangular cross-section spreading along the a-axis (see Fig. 1). These channels are filled by crystallization water molecules.
Fig. 4. Projection view along the a-axis of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O. The coordination polyhedron of the Er(III) ions have been drawn.
In this crystal structure, the smallest intermetallic distances ˚ along the a-axis and in the molecular planes are roughly 6.44 A ˚ in the other directions. The shortest lie in the range of 10–12 A ˚ interplanes Gd–Gd distances lie between 6 and 7 A. As far as metallic centers are concerned, the channels’ section can be described as an almost perfect rectangle. The longest sides ˚ long and the smallest sides 11.8 A ˚ long. are roughly 16.5 A 3.2. Estimated porosity of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 ·9H2 O This compound has been obtained only in gel medium and until now, despite great synthetic efforts, it has not been possible to obtain it as a microcrystalline powder. Therefore, since no measurement of its porosity was possible, we have estimated it by a computational method. We have formally partially dehydrate the compound: the crystallization water molecules (easy to remove experimentally) are formally removed while the coordination water molecules (strongly bounded to the metal ions) are not. This computational method based on Connolly’s algorithm [28] has already been described and successfully
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Fig. 5. Projection view of an extended asymmetric unit along with the numbering scheme for compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O.
Fig. 6. Porosity profile of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O.
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used elsewhere [29]. Thanks to it, the porosity of a partially dehydrated material can be calculated on the basis of its crystal structure. In order to compare the results of the calculations with experimental values, we have used a probe ˚ that is the usual kinetic sphere presenting a radius of 1.8 A radius of N2 [30]. With this value the potential specific accessible surface of compound Gd[(C10 H4 )(COO)3 (COOH)](H2 O)4 is 522 m2 g−1 . Furthermore, this method allows to obtain the biggest kinetic radius a guest molecule can present for being hosted by the structure. As can be seen on the porosity profile (reported in Fig. 3), this compound is able to host molecules ˚ This is in perfect agreewith kinetic radii as big as 3.25 A. ment with what could be anticipated from the crystallographic data. 3.3. Crystal structure description of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O
4. Conclusions and outlook We have reported here the two first examples of lanthanide-based coordination polymers involving 1,4,5,8naphtalene-tetra-carboxylate as ligand. Both present rather high dimensionality. Thanks to Connolly’s approach we have also estimated their potential porosity. In both cases the obtained values are rather high. This confirms the validity of our approach. Up to now, these two compounds have been only obtained with Er3+ and Gd3+ ions, respectively. It would be very interesting to extend the families to other lanthanide ions exhibiting catalytic or optical properties. Furthermore, until now, they are not available for technical applications or even for further physical measurements because we have obtained them only as single crystal in gel media. We are currently working for obtaining them as microcrystalline powders. Acknowledgements
The second compound crystallizes in the monoclinic ˚ system, space group P21 /c (no. 14) with a = 9.8442(1) A, ◦ ˚ ˚ b = 29.2288(2) A, c = 10.8795(1) A, β = 92.1767(3) and Z = 4. Its crystal structure is 3D and presents some large channels with rectangular sections spreading along the a-axis (see Fig. 4). The channels are full of crystallization water molecules. There are two crystallographically independent Er(III) ions in this structure (see Fig. 5). The first one (Er1) is eight coordinated by two oxygen atoms from coordination water molecules and six oxygen atoms from four carboxylato groups (a bidentate one and three unidentate) from three different ligands. Its coordination polyhedron can be described as a slightly distorted tricapped trigonal prism. The second Er(III) ion (Er2) is eight-coordinated by eight oxygen atoms. Three out of them are oxygen atoms from coordination water molecules and the five others are belonging to four carboxylate groups from four different ligands (one bidentate and three monodentate). The coordination polyhedron is also best described by a distorted tricapped trigonal prism. There are two independent ligands in the crystal structure. One of them presents two bridging and two bidentate carboxylate functions while the other presents two bridging and two monodentate carboxylate functions. As far as metallic ions are concerned, the section of the channels can be described as a slightly distorted irregular hexagon. The two longest sides of this irregular hexagon are roughly ˚ long while the four shortest lie in the range of 4.9–5.5 A. ˚ 10.3 A 3.4. Estimated porosity of compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 ·12H2 O Once again we have not succeeded until now to obtain this compound as a microcrystalline powder. Therefore we have applied the same procedure as described above for estimating the potential porosity of this compound. Actually, ˚ we obtained a potenusing a probe sphere radius of 1.8 A tial specific accessible surface of 744 m2 g−1 for compound Er4 [(C10 H4 )(COO)4 ]3 (H2 O)10 . The porosity profile (Fig. 6) reveals that this compound is able to host molecules with kinetic ˚ radii as big as 2.25 A.
The authors thank the “R´egion Bretagne” for financial support. The Center of Crystallography of the “Universit´e de Rennes” is acknowledged for recording crystallographic data. References [1] O.M. Yaghi, H. Li, T.L. Groy, J. Am. Chem. Soc. 118 (1996) 9096–9101. [2] J.L.C. Rowsell, O.M. Yaghi, Micropor. Mesopor. Mater. 73 (2004) 3–14. [3] H.K. Chae, D.Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A.J. Matzger, M. O’Keeffe, O.M. Yaghi, Nature 427 (2004) 523–527. [4] F. Serpaggi, T. Luxbacher, A.K. Cheetham, G. Ferey, J. Solid State Chem. 145 (1999) 580–586. [5] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi, Science 295 (2002) 469–472. [6] S.S. Kaye, J.R. Long, J. Am. Chem. Soc. 127 (2005) 6506–6507. [7] O. Guillou, C. Daiguebonne, in: K.A. Gschneider, J.-C.G. B¨unzli, V.K. Pecharsky (Eds.), Handbook on the Physics and Chemistry of Rare Eaths, vol. 34, Elsevier, 2005, pp. 359–404. [8] C. Daiguebonne, Y. G´erault, O. Guillou, A. Lecerf, K. Boubekeur, P. Batail, M. Kahn, O. Kahn, J. Alloys Compd. 275–277 (1998) 50–53. [9] C. Daiguebonne, O. Guillou, K. Boubekeur, Inorg. Chim. Acta 304 (2000) 161–169. [10] A. Deluzet, O. Guillou, Acta Crystallogr. C 59 (2003) m277–m279. [11] O. Guillou, C. Daiguebonne, M. Camara, N. Kerbellec, Inorg. Chem. 45 (21) (2006) 8468–8470. [12] T. Devic, C. Serre, N. Audebrand, J. Marrot, G. F´erey, J. Am. Chem. Soc. 127 (2005) 12788–12789. [13] A. Deluzet, W. Maudez, C. Daiguebonne, O. Guillou, Crystal Growth Des. 3 (2003) 475–479. [14] H.K. Henisch, Crystal Growth in Gels, The Pennsylvania State University Press, 1970, pp. 1–196. [15] H.K. Henisch, Crystals in Gels and Liesegang Rings, Cambridge University Press, Cambridge, 1988. [16] nonius COLLECT, KappaCCD software, Delft, The Netherlands, 1998. [17] Z. Otwinowski, W. Minor, Methods Enzymol. (1997) 307–326. [18] N.W. Alcock, Cryst. Comput. (1970) 271. [19] W.R. Busing, H.A. Levy, Acta Crystallogr. 10 (1957) 180–182. [20] P. Coppens, L. Leiserowitz, D. Rabinovitch, Acta Crystallogr. 18 (1965) 1035–1038. [21] C. Katayama, Acta Crystallogr. A 42 (1986) 19–23. [22] R.H. Blessing, Acta Crystallogr. A 51 (1995) 33–38. [23] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837–838.
N. Kerbellec et al. / Journal of Alloys and Compounds 451 (2008) 377–383 [24] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr. 32 (1999) 115–119. [25] G.M. Sheldrick, T.R. Schneider, Macromol. Crystallogr. Part B (1997) 319–343. [26] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467–473.
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[27] G.M. Sheldrick, Acta Crystallogr. D 49 (1993) 18–23. [28] M.L. Connolly, Science 221 (1983) 709–713. [29] C. Daiguebonne, N. Kerbellec, K. Bernot, Y. G´erault, A. Deluzet, O. Guillou, Inorg. Chem. 45 (2006) 5399–5406. [30] N. Rosi, J. Kim, M. Eddaoudi, B. Chen, M. O’Keeffe, O.M. Yaghi, J. Am. Chem. Soc. 127 (2005) 1504–1518.