Synthesis and Characterization of Three-Dimensional 3d-3d and 3d-4f Heterometallic Coordination Polymers with High Thermal Stability Peng Ren, Wei Shi, and Peng Cheng*
CRYSTAL GROWTH & DESIGN 2008 VOL. 8, NO. 4 1097–1099
Department of Chemistry, Nankai UniVersity, Tianjin 300071, P. R. China ReceiVed August 6, 2007; ReVised Manuscript ReceiVed January 21, 2008
ABSTRACT: Using 1,2-bis(4-pyridyl)ethane (bpe) and benzene-1,3-biscarboxylic acid (H2bba) as ligands, two novel heterometallic threedimensional coordination polymers {[Zn3Mn1.5(bpe)(bba)4(Hbba)] · bpe}n (Mn-Zn) and {[Zn2Pr(bpe)(bba)3(Hbba)] · H2O}n (Pr-Zn) were isolated under hydrothermal conditions. Both complexes are constructed via 3d-3d and 3d-4f clusters as secondary building units, respectively, which represent the first template synthesis for 3D heterometallic MOFs. Metal-directed supramolecular self-assembly1 has produced fascinating results in the crystal design and engineering of various topologies with interesting properties, such as enantioselective separation and catalysis,2 molecular magnets,3 hydrogen-storage materials,4 and multifunctional molecules.5 Considerable research effort has been devoted to design and synthesis of novel metal-organic frameworks (MOFs). For example, large inorganic anions can be employed as templates to build novel microporous MOFs whereas the host segments should be changed into metal ions, organic linkers and/or cationic metal-organic complexes during the assembly.6 On the other hand, the syntheses of 3D MOFs have so far been exclusively centered on monometallic 3D coordination polymers,7 whereas the chemistry as well as the synthetic strategy toward heterometallic coordination polymers has received less attention. In our previous studies8 and other relevant correlative research,9 a series of 3D heterometallic 3d-4f MOFs were synthesized without templates. To continue our research, organic molecule 1,2-bis(4pyridyl)ethane (bpe) was employed in the hydrothermal synthesis, and we successfully isolated three-dimensional 3d-3d and 3d-4f coordination polymers based on benzene-1,3-biscarboxylate acid (H2bba). (Mn-Zn) and {[Zn3Mn1.5(bpe)(bba)4(Hbba)] · bpe}n {[Zn2Pr(bpe)(bba)3(Hbba)] · H2O}n (Pr-Zn) were obtained under hydrothermal conditions,10 which were structurally characterized by X-ray single-crystal diffraction.11 The first unique structural feature of Mn-Zn is that trinuclear Zn-Mn-Zn and hexanuclear Zn-Mn-Zn-Zn-Mn-Zn clusters act as secondary building units (SBUs). As shown in Figure 1, four carboxylates of different bba as bridged ligands link one Mn and two Zn ions. One nitrogen atom of bpe and oxygen atoms of bba complete the five and four-coordinated spheres of the terminal Zn(II) ions for trinuclear and hexanuclear clusters, respectively. All Mn ions in these clusters are coordinated via six O atoms with the Mn-O bond lengths range from 2.13(4) to 2.22(4) Å. Considering the 3D MOF without bpe, we give a 3D open network with two kinds of channels along the a direction (Figure 1c). Both trinuclear and hexanuclear SBUs acting as nodes linked via bba construct grids with the dimensions of 15.2 × 10.1 Å2 and 24.1 × 15.6 Å2 (based on the Mn · · · Mn distance), respectively. The bpe molecules occupy the channels of 3D MOF as free ligands in large channels and coordinated with Zn in small channels (Figure 1d). To the best of our knowledge, Mn-Zn is the first example of 3D 3d-3d heterometallic MOFs based on organic templates. Using this synthesis strategy, we want to know whether 3d-4f 3D MOFs could be constructed. Taking Pr(OH)3 instead of MnCl2 * Corresponding author. E-mail:
[email protected].
in the same synthesis condition, 3D heterometallic MOF Pr-Zn is isolated. Different from Mn-Zn, the SBUs of this compound (Pr-Zn) is trinuclear Zn-Pr-Zn clusters, linked by six carboxylates. These clusters are further linked by bba to form a 3D network with two kinds of channels. One is occupied by bba ligands and water molecules, whereas the other is occupied by two bpe molecules in a cross mode (Figure 2). Thermogravimeric analysis (Figure 3) of the polycrystalline samples showed no decomposition of the coordination frameworks until ca. 420 and 413 °C for Mn-Zn and Pr-Zn, respectively, showing that both coordination polymers have high thermal stability. The slight weight loss of 1.8% for Pr-Zn above 165 °C corresponds to the loss of one lattice–water molecules (calculated 1.6%). Though the removal temperature of free bpe in air is below 300 °C, the uncoordinated and coordinated bpe in MOFs of both compounds prevent from oxidation below 400 °C, implying that microporous MOFs can storage organic molecules in higher temperature. A variedtemperature PXRD of Pr-Zn was performed. The result exhibits that the departure of the guest water molecules does not lead to any phase transformation and the coordination network of Pr-Zn nearly remains the same (see the Supporting Information, Figure S1). We further performed the following experiments: (i) dehydration: the crystal sample of Pr-Zn was heated at 200 °C until the full weight loss of water molecules and the IR peak at 3419 cm-1 disappeared, which shows that the dehydration was completed; (ii) rehydration: the dehydrated samples were exposed to water vapor for about 24 h, and then IR and TGA measurements were performed (IR appears 3419 cm-1 band, TGA weight loss is similar with the original Pr-Zn, which suggested that the rehydration had been completed. We can conclude that Pr-Zn has potential use as microporous materials. Informative magnetic susceptibility measurements of Mn-Zn have been performed on a Quantum Design MPMS-5S superconducting quantum interference device (SQUID) magnetometer in the 2–300 K temperature range. The diamagnetic correction was evaluated by using Pascal’s constants. The room temperature µeff value of 7.31 µB is slightly larger than the value of 7.25 µB, that is, the spin-only value expected for Mn1.5Zn3 units with isotropic g ) 2.0. As the temperature decreases, the value of µeff increases to 7.54 µB at 80 K, implying weak ferromagnetic interactions. Below this temperature it decreases to the minimum of 6.87 µB at 2 K. The Curie–Weiss fit gives a C value of 6.48 emu K mol-1 and a θ value of 0.32 K (in the temperature range 2–300 K), confirming very weak ferromagnetic interactions in Mn-Zn. Considering the structural features, the distances between neighbor Mn atoms are larger than 10 Å, and the exchange interaction can thus be expected to be weak.
10.1021/cg700740m CCC: $40.75 2008 American Chemical Society Published on Web 03/05/2008
1098 Crystal Growth & Design, Vol. 8, No. 4, 2008
Communications
Figure 1. (a) Trinuclear Zn-Mn-Zn and (b) hexanuclear Zn-Mn-Zn-Zn-Mn-Zn clusters as secondary building units and the 3D MOFs (c) without and (d) with bpe in Mn-Zn. Yellow, C; blue, N; red, O; purple, Mn; green, Zn.
Figure 2. 3D Pr-Zn MOFs: (a) polyhedral representation, (b) wire model. Yellow, C; blue, N; red, O; purple, Pr; green, Zn.
Figure 3. TGA curves of both complexes.
In summary, two novel 3D 3d-3d and 3d--4f microporous MOFs with high thermal stability were synthesized, which first provides a synthesis strategy for building of 3D heterometallic MOFs by organic templates. Further studies for constructing novel 3D heterometallic MOFs are underway in order to give potential useful materials.
Figure 4. Pots of µeff and χM-1 vs T of Mn-Zn; the solid line is the best fitting by Curie–Weiss law.
Acknowledgment. This work was supported by the National Natural Science Foundation of China (Grants 20631030 and 20425103), the State Key Project of Fundamental Research of MOST (Grants 2007CB815305 and 2007AA05Z109), and the “100 Projects” of Creative Research for Undergraduates of Nankai University.
Communications
Crystal Growth & Design, Vol. 8, No. 4, 2008 1099
Supporting Information Available: X-ray crystallographic files in CIF format for Mn-Zn andPr-Zn. Simulated and a varied-temperature powder XRD patterns for Pr-Zn (PDF).This material is available free of charge via the Internet at http://pubs.acs.org.
References (1) (a) Moulton, B.; Zaworotko, M. J. Chem. ReV. 2001, 101, 1629. (b) Evans, O. R.; Lin, W. B. Acc. Chem. Res. 2002, 35, 511. (2) (a) Dincá, M.; Long, J. R. J. Am. Chem. Soc. 2005, 127, 9376. (b) Barbour, L. J. Chem. Commun. 2006, 1163. (c) Bradshaw, D.; Prior, T. J.; Cussen, E. J.; Claridge, J. B.; Rosseinsky, M. J. J. Am. Chem. Soc. 2004, 126, 6106. (3) (a) Coronado, E.; Galan-Ma’scaro’s, J. R.; Go’mez-Garci’a, C. J.; Laukhin, V. Nature 2000, 408, 447. (b) Kahn, O. Molecular Magnetism; VCH: Weinheim, Germany, 1993. (4) (a) Eddaoudi, M.; Kim, J.; Rosi, N.; Vodak, D.; Wachter, J.; O’Keeffe, M.; Yaghi, O. M. Science 2002, 295, 469. (b) Dinca, M.; Dailly, A.; Liu, Y.; Brown, C. M.; Neumann, D. A.; Long, J. R. J. Am. Chem. Soc. 2006, 128, 16876. (5) (a) Sato, O. Acc. Chem. Res. 2003, 36, 692. (b) Maspoch, D.; RuizMolina, D.; Veciana, J J. Mater. Chem. 2004, 2713. (c) Kurmoo, M.; Kumagai, H.; Chapman, K. W.; Kepert, C. J. Chem. Commun. 2005, 3012. (d) Imai, H.; Inoue, K.; Kikuchi, K.; Yoshida, Y.; Ito, M.; Sunahara, T.; Onaka, S. Angew. Chem., Int. Ed. 2004, 43, 5618. (e) Gao, E. Q.; Yue, Y. F.; Bai, S. Q.; He, Z.; Yan, C.-H. J. Am. Chem. Soc. 2004, 126, 1419. (6) (a) Bunzli, J. C. G.; Piguet, C. Chem. ReV. 2002, 102, 1897. (b) Muller, A.; Beugholt, C.; Bogge, H.; Schmidtmann, M. Inorg. Chem. 2002, 39, 3112. (7) (a) Matsuda, R.; Kitaura, R.; Kitagawa, S.; Kubota, Y.; Belosludov, R. V.; Kobayashi, T. C.; Sakamoto, H.; Chiba, T.; Takata, M.; Kawazoe, Y.; Mita, Y. Nature 2005, 436, 238. (b) Ferey, G.; MellotDraznieks, C.; Serre, C.; Millange, F. Acc. Chem. Res. 2005, 38, 217. (c) Ockwig, N. W.; Delgado-Friedrichs, O.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2005, 38, 176. and reference therein. (8) (a) Zhao, B.; Cheng, P.; Chen, X. Y.; Cheng, C.; Shi, W.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. J. Am. Chem. Soc. 2004, 126, 3012. (b) Zhao, B.; Chen, X. Y.; Cheng, P.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H. J. Am. Chem. Soc. 2004, 126, 15394. (c) Zhai, B.; Yi, L.; Wang, H.-S.; Zhao, B.; Cheng, P.; Liao, D.-Z.; Yan, S.-P. Inorg. Chem. 2006, 45, 8471. (d) Wang, Y.; Cheng, P.; Chen, J.; Liao, D.-Z.; Yan, S.-P. Inorg. Chem. 2007, 46, 4530. (f) Zhao, B.; Cheng, P.; Dai, Y.; Cheng, C.; Liao, D. Z.; Yan, S. P.; Jiang, Z. H.; Wang, G. L. Angew. Chem., Int. Ed. 2003, 42, 934.
(9) (a) Wang, F. Q.; Zheng, X. J.; Wan, Y. H.; Sun, C. Y.; Wang, Z. M.; Wang, K. Z.; Jin, L. P. Inorg. Chem. 2007, 46, 2956. (b) Wu, G.; Hewitt, I. J.; Mameri, S.; Lan, Y. H.; Clerac, R.; Anson, C. E.; Qiu, S. L.; Powell, A. K. Inorg. Chem. 2007, 46, 7229. (c) Aronica, C.; chastanet, G.; Pilet, G.; Guennic, B. L.; Robert, V.; Wernsdorfer, W.; Luneau, D. Inorg. Chem. 2007, 46, 6108. (d) Luo, F.; Batten, S. R.; Che, Y. X.; Zheng, J. M. Chem.sEur. J. 2007, 13, 4948. (e) Mereacre, V. M.; Ako, A. M.; Clerac, R.; Wernsdorfer, W.; Filoti, G.; Bartolome, J.; Anson, C. E.; Powell, A. K. J. Am. Chem. Soc. 2007, 129, 9248. (g) Plecnik, C. E.; Liu, S.; Shore, S. G. Acc. Chem. Res. 2003, 36, 499. (10) Synthesis of Mn-Zn. Mn-Zn was obtained by mixing ligand H2bba (1.0 mmol, 0.166 g), bpe (0.5 mmol, 0.092 g), MnCl2 (0.5 mmol, 0.117 g), Zn(NO3)2 (0.5 mmol, 0.149 g), and 10 mL of H2O in a Teflon-lined vessel (25 mL) and then heating at 180 °C for three days. After being cooled freely to room temperature, single crystals suitable for X-ray diffraction were isolated from the resulting solution with a yield of 65%. Elemental anal. Calcd for Mn-Zn: C, 51.71; H, 3.19; N, 3.77. Found: C, 51.89; H, 3.23; N, 3.66. ICP, Mn:Zn ) 1:2. IR, 3417 (vs), 2031 (w), 1558 (vs), 1518 (s), 1431 (w), 1337 (w), 1124 (w), 781 (w), 621 (w) cm-1. Synthesis of Pr-Zn. Pr-Zn was obtained by a method similar to that of Mn-Zn by using Pr(OH)3 (0.4 mmol, 0.0768 g) replacing MnCl2 with a yield of 60%. Elemental anal. Calcd for Pr-Zn: C, 46.71; H, 2.76; N, 2.48. Found: C, 46.72; H, 2.80; N, 2.38. IR, 3419 (vs), 2032 (w), 1557 (s), 1518 (vs), 1415 (s), 1337 (w), 1124 (w), 782 (w), 621 (w) cm-1. (11) Crystal data: for Mn-Zn, triclinic, P1j, a ) 10.426(2) Å, b ) 14.962(3) Å, c ) 21.102(4) Å, R ) 100.01(3)°, β ) 93.54(3)°, γ ) 106.90(3)°, V ) 3079.6(10) Å3, Z ) 2, F(000) ) 1509, GOF ) 1.047, R1 ) 0.0687, wR2 ) 0.1487 [I > 2σ(I)]; for Pr-Zn, monoclinic, P2(1)/c, a ) 10.4903(13) Å, b ) 18.331(2) Å, c ) 22.282(3) Å, β ) 92.231(2)°, V ) 4281.5(9) Å3, Z ) 4, F(000) ) 2256, GOF ) 1.003, R1 ) 0.0393, wR2 ) 0.0729 [I > 2σ(I)]. Structural measurements were both performed on a Bruker SMART 1000 CCD diffractometer equipped with graphite-monochromated Mo KR radiation with radiation wavelength 0.71073 Å by using the ω-φ scan technique. The structures were solved by direct methods and refined with the fullmatrix least-squares technique using the SHELXS-97 and SHELXL97 programs.12 (12) (a) Sheldrick, G. M., SHELXS-97, Program for X-ray Crystal structure Solution; Göttingen University: Göttingen, Germany, 1997. (b) Sheldrick, G. M., SHELXL-97, Program for X-ray Crystal Structure Refinement; Göttingen UniversityGöttingen, Germany, 1997.
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