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A highly rare (3,4,5,6)-connected metal–organic framework containing three distinct Co2 secondary building units
Inorganic Chemistry Communications 13 (2010) 671–675
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Inorganic Chemistry Communications j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / i n o c h e
A highly rare (3,4,5,6)-connected metal–organic framework containing three distinct Co2 secondary building units Feng Luo ⁎, Yang Ning, Xiao-lan Tong, Ming-biao Luo College of Biology, Chemistry and Material Science, East China Institute of Technology, Fuzhou (344000), Jiangxi, China
a r t i c l e
i n f o
Article history: Received 14 January 2010 Accepted 2 March 2010 Available online 15 March 2010 Keywords: MOF Multi-nodal framework Porous materials Phase transition
a b s t r a c t Via solvothermal reaction of CoCl2 with H3BTC (1,3,5-benzenetricarboxylic acid) in DMF–C2H5OH, a new metal–organic framework (MOF) was isolated. The single crystal X-ray diffraction suggests that the asymmetric unit contains six crystallography-independent Co(II) ions and four deprotonated BTC3− ligands, and the overall structure of it is a 3D microporous framework with three-dimensional intersecting channel. Further topological analysis reveals a highly rare (3, 4, 5, 6)-connected net. © 2010 Elsevier B.V. All rights reserved.
The design and preparation of coordination polymers has developed rapidly in recent years [1]. Work along this line is mainly motivated by their intriguing molecular topologies [2] and crystal packing motifs, along with their potential applications in many fields [3]. Especially in the realm of metal–organic frameworks (MOFs), the classification and nomenclature launched by Wells [4,5] and O'Keeffe [6,7] are becoming increasingly important issues as more and more examples of 3D nets are obtained, or deliberately synthesized. In light of their reviews [4–7], most of MOFs can be classified to be, a) uninodal frameworks that contain one kind of vertex and one kind of edge, or b) binodal frameworks built on two kinds of vertex and one kind of edge. The current-developed uninodal MOFs contain the 3-connected SrSi2 (or ThSi2), 4-connected diamond (or CdSO4, NbO, Quartz, SrAl2, PtS), 5-connected BN, 6-connected pcu, 8-connected bcu, as well as 12connected fcu matrix [4–9]. For binodal system, most of reports feature (3, 4)-, (3, 6)-, or (4, 6)-connected nets, [6,7,10–13] and several cases are (3, 5)-, (3, 8)-, (3, 9)-, (4, 8)-, (4, 12)-, (4, 10)-, or (6, 8)-connected nets [6,7,14–20]. Recently, several multi-nodal frameworks such as trinodal MOFs are also obtained and topologically characterized [21–23]. However, to our best of knowledge, there is still not a precedent where the nodes afford more than three kinds of connectivity, so far. Thereby, the topic of multi-nodal MOFs is still a big challenge. In literature, H3BTC (1,3,5-benzenetricarboxylic acid) ligand was extensively employed to generate topological architecture or microporous MOFs [24–29]. In our previous studies, [30–33] we also found that the combination of H3BTC and d-block metal ions
⁎ Corresponding author. Tel./fax: +86 794 8258320. E-mail address: [email protected] (F. Luo). 1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2010.03.016
(such as Cu(II), Co(II), Zn(II)) is a good approach for the preparation of binodal net, where BTC3− and metal ions (or Secondary Building Units, SBUs) usually afford three and four (or six) connectivity, respectively. Herein, we report another MOF, [H2N(CH3)2]4[Co10(BTC)8(DMF)4(μ-C2H5OH)2 (μ-H2O)2] ⊃ (solvents) (denoted as 1 ⊃ (solvents), HN(CH3)2 = dimethylamide, BTC = 1,3,5benzenetricarboxylate) that is obtained by solvothermal reaction of H3BTC and Co(II) ions in DMF–C2H5OH. The structure of it is a multinodal (3, 4, 5, 6)-connected net. The detailed experiment, structure, and property studies are listed below. Via solvothermal synthesis (160 °C) in DMF–C2H5OH (5:1), the self-assembly of CoCl2 and H3BTC in the ratio of 1.5:1 yields polymer 1 ⊃ (solvents). The purple crystals of it are not air-stable and quickly lose the crystal transparence, when it is removed from the mother liquor. Based on the consideration of single crystal X-ray diffraction data, elemental analysis (EA) of the opaque phase (exp. C/39.95, H/ 3.97, N/4.26) suggests the possible chemical formula of [H2N(CH3)2]4 [Co10(BTC)8(DMF)4(μ1-C2H5OH)2(μ1-H2O)2] ⊃ (DMF)1.5(C2H5OH)1.5 (H2O)2 (denoted as 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2, calc. C/40.54, H/ 4.06, N/4.34). If emerging 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2 in DMF or DMF–C2H5OH for 4 weeks, it returns to crystal 1 ⊃ (solvents), clearly indicating that the spontaneous loss of DMF solvent molecules is responsible for the formation of 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2. The [H2N(CH3)2]+ cations are derived from the hydrolyzed DMF molecules [34]. The single crystal X-ray diffraction at 113 K gives the orthorhombic, Ccca space group for 1 ⊃ (solvents), where the solvent molecules and [H2N(CH3)2]+ cations cannot be accurately determined, because of the badly disordered structure of them that are further treated by the Platon Squeeze program. [11] Thereafter, the following structure analysis is based on ‘1-squeeze.cif’ file. In the asymmetry unit of
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Fig. 1. Along b direction, perspective of the framework of 1 ⊃ (solvents) that contains four kinds of meshes marked by A, B, C, D. The colored bigger balls are the coordinated H2O, C2H5OH, and DMF molecules (O/red, C/green, and N/blue). Schematic description of the (3, 4, 5, 6)-connected topology framework of 1 ⊃ (solvents), and its SBUs. The arrow denotes the location of each node. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 2. The left, view of the 3D framework of 1 ⊃ (solvents) with three-dimensional intersecting channel (colored by gray and blue) and isolated one-dimensional honeycomb-like channel; the right, view of the three-dimensional intersecting channel (colored by gray and blue) with isolated one-dimensional honeycomb-like channel. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
F. Luo et al. / Inorganic Chemistry Communications 13 (2010) 671–675
1 ⊃ (solvents), there are five Co(II) ions and four completely deprotonated BTC3− ligands; thereby, based on the considerations of charge balance, the presence of [H2N(CH3)2]+ counterions are suggested. Co1, Co2, Co4, and Co6 atoms hold the position occupation of 1.0, while Co3 and Co5 take the position occupation of 0.5. Co1 and Co3 atoms are six-coordinated by six BTC3− oxygens to form octahedral geometry, whereas the octahedral geometry of Co2, Co4, Co6 is completed by BTC3− oxygens plus terminal solvent ligands (such as DMF for Co2, DMF and H2O for Co6, as well as C2H5OH for Co4). Only Co5 adopts CoO4 tetrahedral geometry completed by four BTC3− oxygens. The Co–O bond lengths vary from 1.958 to 2.362 Ǻ, comparable with that observed in other Co-based compounds [34].
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Co1, Co2, and Co4, and Co6 are bridged by two BTC carboxyl groups and one carboxylate oxygen atoms to give rise to the Co2(CO2)5 and Co2(CO2)4 secondary building units (SBUs), where the Co…Co distance and Co–O–Co angle are 3.433 Ǻ/106.43° for Co1–Co2 and 3.334 Ǻ/104.44° for Co4–Co6. Similarly, Co3 and Co5 are associated together by two BTC carboxyl groups to create Co2(CO2)6 SBU with the Co…Co distance of 4.045 Ǻ. The BTC ligands adopt the μ4:ŋ1:ŋ1:ŋ1:ŋ1: ŋ1:ŋ0, μ5:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1:ŋ2, and μ5:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1 coordinated modes. For polymer 1 ⊃ (solvents), one outstanding structure feature is the rarely three-dimensional intersecting channel. As shown in Fig. 1, along b direction, 1 ⊃ (solvents) shows four kinds of channels, A, B, C, and D, occupied by solvent molecules and [H2N(CH3)2]+ counterions.
Fig. 3. Schematic description of the connectivities and geometry for BTC3− organic spacers and Co2 SBUs: the four topologically different BTC3− ligands are distinguished by four distinct colors. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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The solvent-accessible volume estimated by Platon program is 15667.7 Ǻ3, equal to 48.8% of the cell volume, indicating potential porous framework of it [35]. With the consideration of the atom radius, the smallest channel, D, owns the aperture of ca. 2.0 Ǻ, while the rhombic channel, A, and the honeycomb-like channels, B and C, provide the dimension of ca. 6.7 × 6.8, 6.3 × 5.1, 3.8 × 2.2 Ǻ2, respectively. Notably, as shown in Fig. 2, except that channel, B, is onedimensional, channels, A, C, and D, intersect together, leading to the three-dimensional intersecting channel. In literature, porous MOFs owning one-dimensional channels are often encountered [36,37]. However, to our best of knowledge, the case featuring threedimensional intersecting channel is still less developed. Another outstanding structure feature of 1 ⊃ (solvents) is the multi-nodal topological framework. The better insight of it can be achieved by topology analysis. General speaking, this framework is composed of Co2 SBUs and BTC3− spacers. From a topological point of view, the 3D matrix of it is quite complicated, as there are three distinct Co2 SBUs and the linking fashion between BTC3− spacers and Co2 SBUs for each BTC3− spacer is also different. Thus, in order to distinguish the difference, the four BTC3− spacers are defined as BTC(I), BTC(II), BTC(III), and BTC(IV), while Co4–Co6, Co1–Co2, and Co3–Co5 pairs are viewed to be SBU(I), SBU(II), and SBU(III). As illustrated in Fig. 3, the connectivity of SBUs is interpreted as below: SBU(I) connects to one BTC(II), one BTC(III), and two BTC(IV) to give four connectivities with tetrahedral geometry; SBU(II) is surrounded by two BTC(I), two BTC(II), and one BTC(IV), providing five connectivities with trigonal bipyramidal geometry; and SBU(III) ligates two BTC(I) and four BTC(III) to afford six connectivities with octahedral geometry. In literature, only the square, tetrahedral, and octahedral geometries for Co2 SBUs have been developed [30–33]. Thereby, the present case should be the first one that contains fiveconnected Co2 SBU with trigonal bipyramidal geometry. The 3connected BTC3− spacers hold four distinct connecting fashions: BTC(I) links to one SBU(II) and two SBU(III); BTC(II) connects to one SBU(I) and two SBU(III); BTC(III) is associated by one SBU(I) and two SBU(II); and BTC(IV) ligates two SBU(I) and one SBU(III). As a result, the connectivity analysis suggests the (3, 4, 5, 6)-connected net and further topology analysis by Topos program gives (63) 2 (4·6·8) 2 (4·62 )2 (4·62 ) 2 (4·63·82)2(4·64·85)2(42·68·84·10) topology notation, [38,39] where two 3-connected BTC3− ligands has the same short Schäfli symbol of 4·62, but different long vertex symbol of 4·6·6 and 4·63·63, respectively. As discussed above, it is believed that the present (3, 4, 5, 6)-connected net is the first multi-nodal net where the nodes show more than three kinds of connectivities.
Fig. 4. The TGA plot of 1 ⊃ (DMF)1.5(C2H5OH)nH2O)2.
The purple crystals of 1 ⊃ (solvents) are air-sensitive and quickly lose the crystal transparence, when it is removed from the mother liquor. The thermogravimetric analysis of the resulted opaque phase, 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2 shows that, at 30–85 °C, the first weight loss of 6.7% corresponds to the release of free solvent molecules (calc. 7.0%), then the removal of coordinated solvent molecules (H2O, C2H5OH, and DMF) is about 80–295 °C (found: 12.6%, calc. 13.6%), afterwards, the loss of [H2N(CH3)2]+ counterions causes the chemical decomposition of this anionic framework (Fig. 4). In conclusion, via solvothermal reaction of CoCl2 with H3BTC in DMF–C2H5OH, we isolated a novel MOF that bears two highlighted properties, viz. rarely three-dimensional intersecting channel with isolated one-dimensional channels, and multi-nodal (3, 4, 5, 6)connected framework that presents the first multi-nodal net with the node showing more than three kinds of connectivities. Acknowledgment This work was supported by the Start-up Fund of the East China Institute of Technology. Appendix A. Supplementary data X-ray crystallographic file in CIF format, detailed experiments, and X-ray structural studies are contained. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j. inoche.2010.03.016. References [1] O.M. Yaghi, C.E. Davis, G.M. Li, H. Li, J. Am. Chem. Soc. 119 (1997) 2861. [2] M.J. Zaworotko, Angew. Chem. Int. Ed. 39 (2000) 3052. [3] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O'Keeffe, O.M. Yaghi, Science 295 (2002) 469. [4] A.F. Wells, Three-Dimensional Nets and Polyhedra, Wiley-Interscience, New York, 1977. [5] A.F. Wells, Acta Crystallogr. A: Found. Crystallogr. A 42 (1986) 133. [6] M. O'Keeffe, B.G. Hyde, Crystal Structures, I, Patterns and Symmetry, Mineralogical Society of America, Washington, DC, 1996. [7] M. O'Keeffe, M. Eddaoudi, H. Li, T. Reineke, O.M. Yaghi, J. Solid State Chem. 152 (2000) 3. [8] J.J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem. Int. Ed. 40 (2001) 2113. [9] T.T. Luo, H.L. Tsai, S.L. Yang, Y.H. Liu, R.D. Yadav, C.C. Su, C.H. Ueng, L.G. Lin, K.L. Lu, Angew. Chem., Int. Ed. 44 (2005) 6063. [10] O. Delgado-Friedrichs, M. O'Keeffe, O.M. Yaghi, Acta Cryst. A62 (2006) 350. [11] O. Delgado-Friedrichs, M. O'Keeffe, Acta Cryst. A61 (2005) 358. [12] D.N. Dybtsev, H. Chun, K. Kim, Chem. Commun. (2004) 1594. [13] D.-R. Xiao, E.-B. Wang, H.-Y. An, Y.-G. Li, Z.-M. Su, C.-Y. Sun, Chem. Eur. J. 12 (2006) 6528. [14] S.-Z. Zhan, D. Li, X.-P. Zhou, X.-H. Zhou, Inorg. Chem. 45 (2006) 9163. [15] R.-Q. Zou, R.-Q. Zhong, M. Du, T. Kiyobayashia, Q. Xu, Chem. Commun. (2007) 2467. [16] S.Q. Ma, H.-C. Zhou, J. Am. Chem. Soc. 128 (2006) 11734. [17] M. Dincã, J.R. Long, J. Am. Chem. Soc. 127 (2005) 9376. [18] X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, Y.-G. Li, L. Xu, Angew. Chem. Int. Ed. 45 (2006) 7411. [19] Y.-Q. Lan, X.-L. Wang, S.-L. Li, Z.-M. Su, K.-Z. Shao, E.-B. Wang, Chem. Commun. (2007) 4863. [20] X.L. Wang, G.C. Liu, J.X. Zhang, Y.Q. Chen, H.Y. Lin, W.Y. Zheng, Dalton Trans. (2009) 7347. [21] Y.-J. Shi, X.-T. Chen, Y.-Z. Li, Z.L. Xue, X.-Z. You, New J. Chem. 26 (2002) 1711. [22] Q. Fang, G. Zhu, M. Xue, Z. Wang, J. Sun, S. Qiu, Cryst. Growth Des. 8 (2008) 319. [23] F.P. Huang, J.L. Tian, D.D. Li, G.J. Chen, W. Gu, S.P. Yan, X. Liu, D.Z. Liao, P. Cheng, Cryst. Eng. Comm. 12 (2010) 395. [24] C. Livage, N. Guillou, J. Marrot, G. Ferey, Chem. Mater. 13 (2001) 4387. [25] L.H. Xie, S.X. Liu, B. Gao, C.D. Zhang, C.Y. Sun, D.H. Li, Z.M. Su, Chem. Commun. (2005) 2402. [26] Z.-Z. Lin, F.-L. Jiang, L. Chen, C.-Y. Yue, D.-Q. Yuan, A.-J. Lan, M.-C. Hong, Cryst. Growth Des. 7 (2007) 1712. [27] D.T. de Lill, C.L. Cahill, Chem. Commun. (2006) 4946. [28] Q. Fang, G. Zhu, M. Xue, J. Sun, F. Sun, S. Qiu, Inorg. Chem. 45 (2006) 3582. [29] J.H. He, Y.T. Zhang, Q.H. Pan, J.H. Yu, H. Ding, R.R. Xu, Microporous Mesoporous Mater. 90 (2006) 145. [30] F. Luo, J.-M. Zheng, S.R. Batten, Chem. Commun. (2007) 3744. [31] F. Luo, Y.-X. Che, J.-M. Zheng, Inorg. Chem. Commun. 9 (2006) 1045. [32] F. Luo, Y.-X. Che, J.-M. Zheng, Inorg. Eur. J. Inorg. Chem. (2007) 3906. [33] F. Luo, Y.-X. Che, J.-M. Zheng, Cryst. Growth Des. 8 (2008) 176.
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Contents lists available at ScienceDirect
Inorganic Chemistry Communications j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / i n o c h e
A highly rare (3,4,5,6)-connected metal–organic framework containing three distinct Co2 secondary building units Feng Luo ⁎, Yang Ning, Xiao-lan Tong, Ming-biao Luo College of Biology, Chemistry and Material Science, East China Institute of Technology, Fuzhou (344000), Jiangxi, China
a r t i c l e
i n f o
Article history: Received 14 January 2010 Accepted 2 March 2010 Available online 15 March 2010 Keywords: MOF Multi-nodal framework Porous materials Phase transition
a b s t r a c t Via solvothermal reaction of CoCl2 with H3BTC (1,3,5-benzenetricarboxylic acid) in DMF–C2H5OH, a new metal–organic framework (MOF) was isolated. The single crystal X-ray diffraction suggests that the asymmetric unit contains six crystallography-independent Co(II) ions and four deprotonated BTC3− ligands, and the overall structure of it is a 3D microporous framework with three-dimensional intersecting channel. Further topological analysis reveals a highly rare (3, 4, 5, 6)-connected net. © 2010 Elsevier B.V. All rights reserved.
The design and preparation of coordination polymers has developed rapidly in recent years [1]. Work along this line is mainly motivated by their intriguing molecular topologies [2] and crystal packing motifs, along with their potential applications in many fields [3]. Especially in the realm of metal–organic frameworks (MOFs), the classification and nomenclature launched by Wells [4,5] and O'Keeffe [6,7] are becoming increasingly important issues as more and more examples of 3D nets are obtained, or deliberately synthesized. In light of their reviews [4–7], most of MOFs can be classified to be, a) uninodal frameworks that contain one kind of vertex and one kind of edge, or b) binodal frameworks built on two kinds of vertex and one kind of edge. The current-developed uninodal MOFs contain the 3-connected SrSi2 (or ThSi2), 4-connected diamond (or CdSO4, NbO, Quartz, SrAl2, PtS), 5-connected BN, 6-connected pcu, 8-connected bcu, as well as 12connected fcu matrix [4–9]. For binodal system, most of reports feature (3, 4)-, (3, 6)-, or (4, 6)-connected nets, [6,7,10–13] and several cases are (3, 5)-, (3, 8)-, (3, 9)-, (4, 8)-, (4, 12)-, (4, 10)-, or (6, 8)-connected nets [6,7,14–20]. Recently, several multi-nodal frameworks such as trinodal MOFs are also obtained and topologically characterized [21–23]. However, to our best of knowledge, there is still not a precedent where the nodes afford more than three kinds of connectivity, so far. Thereby, the topic of multi-nodal MOFs is still a big challenge. In literature, H3BTC (1,3,5-benzenetricarboxylic acid) ligand was extensively employed to generate topological architecture or microporous MOFs [24–29]. In our previous studies, [30–33] we also found that the combination of H3BTC and d-block metal ions
⁎ Corresponding author. Tel./fax: +86 794 8258320. E-mail address: [email protected] (F. Luo). 1387-7003/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2010.03.016
(such as Cu(II), Co(II), Zn(II)) is a good approach for the preparation of binodal net, where BTC3− and metal ions (or Secondary Building Units, SBUs) usually afford three and four (or six) connectivity, respectively. Herein, we report another MOF, [H2N(CH3)2]4[Co10(BTC)8(DMF)4(μ-C2H5OH)2 (μ-H2O)2] ⊃ (solvents) (denoted as 1 ⊃ (solvents), HN(CH3)2 = dimethylamide, BTC = 1,3,5benzenetricarboxylate) that is obtained by solvothermal reaction of H3BTC and Co(II) ions in DMF–C2H5OH. The structure of it is a multinodal (3, 4, 5, 6)-connected net. The detailed experiment, structure, and property studies are listed below. Via solvothermal synthesis (160 °C) in DMF–C2H5OH (5:1), the self-assembly of CoCl2 and H3BTC in the ratio of 1.5:1 yields polymer 1 ⊃ (solvents). The purple crystals of it are not air-stable and quickly lose the crystal transparence, when it is removed from the mother liquor. Based on the consideration of single crystal X-ray diffraction data, elemental analysis (EA) of the opaque phase (exp. C/39.95, H/ 3.97, N/4.26) suggests the possible chemical formula of [H2N(CH3)2]4 [Co10(BTC)8(DMF)4(μ1-C2H5OH)2(μ1-H2O)2] ⊃ (DMF)1.5(C2H5OH)1.5 (H2O)2 (denoted as 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2, calc. C/40.54, H/ 4.06, N/4.34). If emerging 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2 in DMF or DMF–C2H5OH for 4 weeks, it returns to crystal 1 ⊃ (solvents), clearly indicating that the spontaneous loss of DMF solvent molecules is responsible for the formation of 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2. The [H2N(CH3)2]+ cations are derived from the hydrolyzed DMF molecules [34]. The single crystal X-ray diffraction at 113 K gives the orthorhombic, Ccca space group for 1 ⊃ (solvents), where the solvent molecules and [H2N(CH3)2]+ cations cannot be accurately determined, because of the badly disordered structure of them that are further treated by the Platon Squeeze program. [11] Thereafter, the following structure analysis is based on ‘1-squeeze.cif’ file. In the asymmetry unit of
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Fig. 1. Along b direction, perspective of the framework of 1 ⊃ (solvents) that contains four kinds of meshes marked by A, B, C, D. The colored bigger balls are the coordinated H2O, C2H5OH, and DMF molecules (O/red, C/green, and N/blue). Schematic description of the (3, 4, 5, 6)-connected topology framework of 1 ⊃ (solvents), and its SBUs. The arrow denotes the location of each node. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
Fig. 2. The left, view of the 3D framework of 1 ⊃ (solvents) with three-dimensional intersecting channel (colored by gray and blue) and isolated one-dimensional honeycomb-like channel; the right, view of the three-dimensional intersecting channel (colored by gray and blue) with isolated one-dimensional honeycomb-like channel. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
F. Luo et al. / Inorganic Chemistry Communications 13 (2010) 671–675
1 ⊃ (solvents), there are five Co(II) ions and four completely deprotonated BTC3− ligands; thereby, based on the considerations of charge balance, the presence of [H2N(CH3)2]+ counterions are suggested. Co1, Co2, Co4, and Co6 atoms hold the position occupation of 1.0, while Co3 and Co5 take the position occupation of 0.5. Co1 and Co3 atoms are six-coordinated by six BTC3− oxygens to form octahedral geometry, whereas the octahedral geometry of Co2, Co4, Co6 is completed by BTC3− oxygens plus terminal solvent ligands (such as DMF for Co2, DMF and H2O for Co6, as well as C2H5OH for Co4). Only Co5 adopts CoO4 tetrahedral geometry completed by four BTC3− oxygens. The Co–O bond lengths vary from 1.958 to 2.362 Ǻ, comparable with that observed in other Co-based compounds [34].
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Co1, Co2, and Co4, and Co6 are bridged by two BTC carboxyl groups and one carboxylate oxygen atoms to give rise to the Co2(CO2)5 and Co2(CO2)4 secondary building units (SBUs), where the Co…Co distance and Co–O–Co angle are 3.433 Ǻ/106.43° for Co1–Co2 and 3.334 Ǻ/104.44° for Co4–Co6. Similarly, Co3 and Co5 are associated together by two BTC carboxyl groups to create Co2(CO2)6 SBU with the Co…Co distance of 4.045 Ǻ. The BTC ligands adopt the μ4:ŋ1:ŋ1:ŋ1:ŋ1: ŋ1:ŋ0, μ5:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1:ŋ2, and μ5:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1:ŋ1 coordinated modes. For polymer 1 ⊃ (solvents), one outstanding structure feature is the rarely three-dimensional intersecting channel. As shown in Fig. 1, along b direction, 1 ⊃ (solvents) shows four kinds of channels, A, B, C, and D, occupied by solvent molecules and [H2N(CH3)2]+ counterions.
Fig. 3. Schematic description of the connectivities and geometry for BTC3− organic spacers and Co2 SBUs: the four topologically different BTC3− ligands are distinguished by four distinct colors. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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The solvent-accessible volume estimated by Platon program is 15667.7 Ǻ3, equal to 48.8% of the cell volume, indicating potential porous framework of it [35]. With the consideration of the atom radius, the smallest channel, D, owns the aperture of ca. 2.0 Ǻ, while the rhombic channel, A, and the honeycomb-like channels, B and C, provide the dimension of ca. 6.7 × 6.8, 6.3 × 5.1, 3.8 × 2.2 Ǻ2, respectively. Notably, as shown in Fig. 2, except that channel, B, is onedimensional, channels, A, C, and D, intersect together, leading to the three-dimensional intersecting channel. In literature, porous MOFs owning one-dimensional channels are often encountered [36,37]. However, to our best of knowledge, the case featuring threedimensional intersecting channel is still less developed. Another outstanding structure feature of 1 ⊃ (solvents) is the multi-nodal topological framework. The better insight of it can be achieved by topology analysis. General speaking, this framework is composed of Co2 SBUs and BTC3− spacers. From a topological point of view, the 3D matrix of it is quite complicated, as there are three distinct Co2 SBUs and the linking fashion between BTC3− spacers and Co2 SBUs for each BTC3− spacer is also different. Thus, in order to distinguish the difference, the four BTC3− spacers are defined as BTC(I), BTC(II), BTC(III), and BTC(IV), while Co4–Co6, Co1–Co2, and Co3–Co5 pairs are viewed to be SBU(I), SBU(II), and SBU(III). As illustrated in Fig. 3, the connectivity of SBUs is interpreted as below: SBU(I) connects to one BTC(II), one BTC(III), and two BTC(IV) to give four connectivities with tetrahedral geometry; SBU(II) is surrounded by two BTC(I), two BTC(II), and one BTC(IV), providing five connectivities with trigonal bipyramidal geometry; and SBU(III) ligates two BTC(I) and four BTC(III) to afford six connectivities with octahedral geometry. In literature, only the square, tetrahedral, and octahedral geometries for Co2 SBUs have been developed [30–33]. Thereby, the present case should be the first one that contains fiveconnected Co2 SBU with trigonal bipyramidal geometry. The 3connected BTC3− spacers hold four distinct connecting fashions: BTC(I) links to one SBU(II) and two SBU(III); BTC(II) connects to one SBU(I) and two SBU(III); BTC(III) is associated by one SBU(I) and two SBU(II); and BTC(IV) ligates two SBU(I) and one SBU(III). As a result, the connectivity analysis suggests the (3, 4, 5, 6)-connected net and further topology analysis by Topos program gives (63) 2 (4·6·8) 2 (4·62 )2 (4·62 ) 2 (4·63·82)2(4·64·85)2(42·68·84·10) topology notation, [38,39] where two 3-connected BTC3− ligands has the same short Schäfli symbol of 4·62, but different long vertex symbol of 4·6·6 and 4·63·63, respectively. As discussed above, it is believed that the present (3, 4, 5, 6)-connected net is the first multi-nodal net where the nodes show more than three kinds of connectivities.
Fig. 4. The TGA plot of 1 ⊃ (DMF)1.5(C2H5OH)nH2O)2.
The purple crystals of 1 ⊃ (solvents) are air-sensitive and quickly lose the crystal transparence, when it is removed from the mother liquor. The thermogravimetric analysis of the resulted opaque phase, 1 ⊃ (DMF)1.5(C2H5OH)(H2O)2 shows that, at 30–85 °C, the first weight loss of 6.7% corresponds to the release of free solvent molecules (calc. 7.0%), then the removal of coordinated solvent molecules (H2O, C2H5OH, and DMF) is about 80–295 °C (found: 12.6%, calc. 13.6%), afterwards, the loss of [H2N(CH3)2]+ counterions causes the chemical decomposition of this anionic framework (Fig. 4). In conclusion, via solvothermal reaction of CoCl2 with H3BTC in DMF–C2H5OH, we isolated a novel MOF that bears two highlighted properties, viz. rarely three-dimensional intersecting channel with isolated one-dimensional channels, and multi-nodal (3, 4, 5, 6)connected framework that presents the first multi-nodal net with the node showing more than three kinds of connectivities. Acknowledgment This work was supported by the Start-up Fund of the East China Institute of Technology. Appendix A. Supplementary data X-ray crystallographic file in CIF format, detailed experiments, and X-ray structural studies are contained. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j. inoche.2010.03.016. References [1] O.M. Yaghi, C.E. Davis, G.M. Li, H. Li, J. Am. Chem. Soc. 119 (1997) 2861. [2] M.J. Zaworotko, Angew. Chem. Int. Ed. 39 (2000) 3052. [3] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O'Keeffe, O.M. Yaghi, Science 295 (2002) 469. [4] A.F. Wells, Three-Dimensional Nets and Polyhedra, Wiley-Interscience, New York, 1977. [5] A.F. Wells, Acta Crystallogr. A: Found. Crystallogr. A 42 (1986) 133. [6] M. O'Keeffe, B.G. Hyde, Crystal Structures, I, Patterns and Symmetry, Mineralogical Society of America, Washington, DC, 1996. [7] M. O'Keeffe, M. Eddaoudi, H. Li, T. Reineke, O.M. Yaghi, J. Solid State Chem. 152 (2000) 3. [8] J.J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem. Int. Ed. 40 (2001) 2113. [9] T.T. Luo, H.L. Tsai, S.L. Yang, Y.H. Liu, R.D. Yadav, C.C. Su, C.H. Ueng, L.G. Lin, K.L. Lu, Angew. Chem., Int. Ed. 44 (2005) 6063. [10] O. Delgado-Friedrichs, M. O'Keeffe, O.M. Yaghi, Acta Cryst. A62 (2006) 350. [11] O. Delgado-Friedrichs, M. O'Keeffe, Acta Cryst. A61 (2005) 358. [12] D.N. Dybtsev, H. Chun, K. Kim, Chem. Commun. (2004) 1594. [13] D.-R. Xiao, E.-B. Wang, H.-Y. An, Y.-G. Li, Z.-M. Su, C.-Y. Sun, Chem. Eur. J. 12 (2006) 6528. [14] S.-Z. Zhan, D. Li, X.-P. Zhou, X.-H. Zhou, Inorg. Chem. 45 (2006) 9163. [15] R.-Q. Zou, R.-Q. Zhong, M. Du, T. Kiyobayashia, Q. Xu, Chem. Commun. (2007) 2467. [16] S.Q. Ma, H.-C. Zhou, J. Am. Chem. Soc. 128 (2006) 11734. [17] M. Dincã, J.R. Long, J. Am. Chem. Soc. 127 (2005) 9376. [18] X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, Y.-G. Li, L. Xu, Angew. Chem. Int. Ed. 45 (2006) 7411. [19] Y.-Q. Lan, X.-L. Wang, S.-L. Li, Z.-M. Su, K.-Z. Shao, E.-B. Wang, Chem. Commun. (2007) 4863. [20] X.L. Wang, G.C. Liu, J.X. Zhang, Y.Q. Chen, H.Y. Lin, W.Y. Zheng, Dalton Trans. (2009) 7347. [21] Y.-J. Shi, X.-T. Chen, Y.-Z. Li, Z.L. Xue, X.-Z. You, New J. Chem. 26 (2002) 1711. [22] Q. Fang, G. Zhu, M. Xue, Z. Wang, J. Sun, S. Qiu, Cryst. Growth Des. 8 (2008) 319. [23] F.P. Huang, J.L. Tian, D.D. Li, G.J. Chen, W. Gu, S.P. Yan, X. Liu, D.Z. Liao, P. Cheng, Cryst. Eng. Comm. 12 (2010) 395. [24] C. Livage, N. Guillou, J. Marrot, G. Ferey, Chem. Mater. 13 (2001) 4387. [25] L.H. Xie, S.X. Liu, B. Gao, C.D. Zhang, C.Y. Sun, D.H. Li, Z.M. Su, Chem. Commun. (2005) 2402. [26] Z.-Z. Lin, F.-L. Jiang, L. Chen, C.-Y. Yue, D.-Q. Yuan, A.-J. Lan, M.-C. Hong, Cryst. Growth Des. 7 (2007) 1712. [27] D.T. de Lill, C.L. Cahill, Chem. Commun. (2006) 4946. [28] Q. Fang, G. Zhu, M. Xue, J. Sun, F. Sun, S. Qiu, Inorg. Chem. 45 (2006) 3582. [29] J.H. He, Y.T. Zhang, Q.H. Pan, J.H. Yu, H. Ding, R.R. Xu, Microporous Mesoporous Mater. 90 (2006) 145. [30] F. Luo, J.-M. Zheng, S.R. Batten, Chem. Commun. (2007) 3744. [31] F. Luo, Y.-X. Che, J.-M. Zheng, Inorg. Chem. Commun. 9 (2006) 1045. [32] F. Luo, Y.-X. Che, J.-M. Zheng, Inorg. Eur. J. Inorg. Chem. (2007) 3906. [33] F. Luo, Y.-X. Che, J.-M. Zheng, Cryst. Growth Des. 8 (2008) 176.
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