- Email: [email protected]
A (3, 4, 10)-connected 3D sandwich-type metal-organic framework with trinuclear zinc(II) cluster and two kinds of discrete zinc(II) ions
Inorganic Chemistry Communications 14 (2011) 1876–1879
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A (3, 4, 10)-connected 3D sandwich-type metal-organic framework with trinuclear zinc(II) cluster and two kinds of discrete zinc(II) ions Sheng-Qi Guo, Dan Tian, Xiang Zheng, Hong Zhang ⁎ Institute of Polyoxometalate Chemistry, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024, PR China
a r t i c l e
i n f o
Article history: Received 19 June 2011 Accepted 17 August 2011 Available online 13 September 2011 Keywords: Crystal structure Biphenyl-2,5,2',5'-tetracarboxylic acid Topology Photoluminescent
a b s t r a c t A new 3D sandwich-type MOF named [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) (H4bptc = biphenyl2,5,2',5'-tetracarboxylic acid) was obtained by solvothermal reaction, which represents a rare trinodal (3, 4, 10)-connected topology network. Moreover, the thermal stability, UV–vis absorption spectra and photoluminescent properties of 1 have been investigated as well. © 2011 Elsevier B.V. All rights reserved.
Much interest has been directed toward the research of novel materials based on metal-organic frameworks (MOFs), which is driven not only by their exploitable applications as functional materials in many fields but also by their novel topologies [1]. Net topology plays an important role of synthesis and analysis MOFs, which has been the subject of many investigations, with fundamental contributions by A.F. Wells, J.V. Smith and M. O'Keeffe [2]. Consequently, various uninodal network topologies have been realized, such as 4-connected dia, 6-connected pcu, 8connected bcu and even higher-connected nets. On the other hand, some metal-organic frameworks exhibit interesting nets containing more than one type of node, for example, binodal anatase, boracite, PtS, rutile and twisted boracite [3]; trinodal (3, 3, 5)-, (3, 4, 4)- and (3, 4, 5)connected nets, etc. [4]. Compared to these commonly encountered mixed-connected topologies, the development of higher connectivity nets is still in its early stages. In the past few years, Lu's and Su's groups reported a few cases of binodal high-connected topologies in succession, examples of (3, 12), (4, 8), (4, 10) and (6, 8)-connected nets [5]. However, there is a disappointing lack of investigation on trinodal high-connected topologies. We are interested in this area and try our best to explore this field. Recently, polynuclear metal clusters with more coordination sites are effectively used as nodes for the constructions of higher-connected topologies due to their large surface areas which are beneficial to accommodate the steric demands of organic linkers [6]. Borrowing ideas from polycarboxylate-metal coordination chemistry [7], adjacent “dense” carboxyl groups reacting with metal ions can form various coordination modes and have the high potential to generate novel
⁎ Corresponding author. Tel.: + 86 431 85099370; fax: + 86 431 85099372. E-mail address: [email protected] (H. Zhang). 1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2011.08.027
metal cluster, which all favor to produce MOFs with fascinating and novel topologies. So we choose biphenyl-2,5,2',5'-tetracarboxylic acid (H4bptc) ligand to prepare the complex. Fortunately, a new 3D coordination polymer [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) (H4bptc = biphenyl-2,5,2',5'-tetracarboxylic acid) is successfully isolated by solvothermal method [8]. Complex 1 represents an interesting sandwich framework with a rare (3, 4, 10)-connected topology. Single crystal X-ray diffraction analysis shows [9] that 1 crystallizes in monoclinic space group C2/c. The structure contains four crystallographically independent Zn(II) ions. As shown in Fig. 1a, Zn1 atom is ligated to four carboxylate oxygen atoms from three different bptc 4− ligands, and exists in a distorted tetrahedral environment. Zn2 atom adopts an octahedral geometry which is completed by six carboxylate oxygen atoms from four different bptc4− ligands. Both Zn3 and Zn4 atoms are five-coordinated surrounded by three carboxylate oxygen atoms from three different bptc 4− ligands and two coordinated water molecules, but exhibit different coordination geometries. Zn3 atom is in a trigonal-bipyramid geometry (τ = 0.640) and Zn4 atom exhibits a distorted square-pyramidal geometry (τ =0.488). The Zn–O bond lengths are in the range of 1.938(2) to 2.2577(18) Å. Interestingly, each Zn2 atom is bridged to two neighboring Zn4 atoms by two –O–C–O– bridges and four μ2-Ocarboxyl atoms to afford a {Zn}3 cluster with a Zn2···Zn4 distance of 3.228 Å. The {Zn}3 clusters are further connected through the bptc4− ligands, Zn1 and Zn3 atoms to form a 3D network. To the best of our knowledge, the simultaneous presence of polynuclear metal cluster and two kinds of discrete metal ions in metal organic framework is rather rare [10]. It is worth noting that bptc 4− ligands show two types of coordination modes (Fig. 1b) in complex 1. The μ7-bridged ligand (Mode I) links two {Zn}3 clusters, two Zn3 atoms and one Zn1 atom. Both carboxylic groups of the Mode I ligand exhibit μ2-η 1:η 1 bridging
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
1877
Fig. 1. (a) Coordination environments of the Zn(II) ions in 1. Hydrogen atoms are omitted for clarity. Symmetry codes: A, −x, 1− y, −z; B, ½− x, 1/2− y, −z; C, −1/2 +x, 1/2 −y, −1/2 +z; D, −x, y, −1/2 −z; E, 1/2− x, 1/2+ y, 1/2− z; F, x, 1− y, 1/2+ z; G, x, 1 − y, −1/2+ z; H, 1− x, y, 1/2− z. (b) The coordination modes of two types of bptc4− ligands in 1.
coordination mode, 2-, 2′-carboxylic groups are in syn-anti conformation, while 5-, 5′-carboxylic groups are in syn-syn conformation. The μ6-bridged ligand (Mode II) connects two Zn3 atoms, one {Zn}3
Fig. 2. Perspective views of (a) the 3-connected Zn3 atom, (b) the 4-connected Zn1 atom and (c) the 10-connected {Zn}3 cluster in 1.
cluster and one Zn1 atom, and 2-, 5-, 2′-, 5′-carboxylic groups of the Mode II ligand exhibit μ3-η1:η2, μ1-η 1:η 0, μ2-η 2:η 0, μ1-η1:η 0 coordination modes, respectively. As a result, each {Zn}3 cluster is surrounded by ten discrete Zn atoms (four Zn1 atoms and six Zn3 atoms), which can be simplified as a 10-connected node (Fig. 2c). Similarly, each Zn1 atom connects four {Zn}3 clusters, and Zn3 atom connects three, respectively, which serve as 4- and 3-connected nodes (Fig. 2b, a). The overall structure of 1 is a 3D (3, 4, 10)-connected framework with the Schläfli symbol of (42·6)2(44·62)(4 16·622·86·10) (Fig. 3d). Offering further insight into the nature of this intricate architecture, each {Zn}3 cluster links four neighboring Zn1 atoms to form a 2D layer (Fig. 3a), which can be described as a 44·62 net (Fig. 3c) in the bc plane. Adjacent 2D layers are further pillared by the Zn3 atoms to furnish a 3D polymer with an extremely ordered sandwich-type framework (Fig. 3b). So the topological net of 1 is changed from 4-connected 44·62 net to a rare trinodal (3, 4, 10)-connected net (Fig. 3d). Among the nets based on polynuclear metal cluster, one trinodal (3, 4, 10)-connected net named [Cd3(L)2(BTA)2(H2O)2]·3H2O [11] (L = 1,2,4,5-tetrakis (imidazol-1-ylmethyl)benzene; H3BTA = 1,3,5-benzenetriacetic acid) with the Schläfli symbol of (42·6)2(44·62)(4 16·622·87) has been reported. By contrast, both of two networks view trinuclear metal cluster as the 10-connected node, but two kinds of multidentate ligands were considered as two low-connected nodes in the reported one. Furthermore, although two topologies have similar symbol and three kinds of nodes in the same proportion relationship, we locate a longer 10member loop in complex 1, which is not observed in the reported one. Therefore, the net in 1 represents not only an inimitable sandwichtype structure but also a unique (3, 4, 10) topology.
1878
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
Fig. 3. (a) Polyhedral view of 2D layer formed by {Zn}3 clusters, Zn1 atoms and bptc4− ligands. (b) Polyhedral view of 3D framework of 1 along the b axis. (c) Schematic description of the 2D 44·62 net of 1. (d) Schematic representation of the trinodal (3, 4, 10)-connected 3D network with (42·6)2(44·62)(416·622·86·10) topology for 1.
In the IR spectrum of the pure complex 1 (Supplementary Fig. S1), the absorption bands resulting from the skeletal vibrations of the aromatic ring are observed in the 1400–1600 cm− 1 region. Complex 1 shows the absorption νas(COO) bands at 1595 cm− 1 and νs(COO) bands at 1381 cm− 1, respectively. In comparison to the free H4bptc organic ligand (Fig. S2), the disappearance of a band at 1689 cm− 1 for 1 is indicative of the full deprotonation of H4bptc. These results are also confirmed by single-crystal structure analysis. The peaks at 3861–3421 cm− 1 for the spectra of 1 can be attributed to the O–H stretch of lattice and coordinated water molecules. The solid-state UV–vis spectra at room temperature of complex 1 is displayed in Fig. S3, complex 1 exhibits strong absorption band at
Fig. 4. The emission spectra of 1 (the excitation wavelength were 277 and 350 nm, respectively) and free H4bptc ligand at room temperature.
248 nm with a weak broad band at 462 nm, tentatively arising from intraligand charge transfer transitions. The photoluminescent properties of the free H4bptc ligand and complex 1 at room temperature are depicted in Fig. 4. The H4bptc ligand displays emission peak at 439 nm upon excitation at 377 nm. Excitation spectrum of complex 1 shows two obvious peaks at 277 and 350 nm (Fig. S4), which yield the emission peaks at 389 and 454 nm, respectively. Since it is difficult to oxidize or reduce the Zn(II) cation due to its d 10 configuration [12], the observed emission for 1 is neither metal-to-ligand charge transfer (MLCT) nor ligand-tometal charge transfer (LMCT). It is probably due to the intraligand (π–π*) fluorescent emissions [13]. Comparing with the free H4bptc ligand, the significantly shifted emission maxima for 1 should be assigned to the deprotonation of the H4bptc ligand and the influence of the coordination of the ligand to metal ions [14]. Thermogravimetric (TG) analysis (Fig. S5) of complex 1 is carried out from room temperature to 800 °C under a nitrogen atmosphere so as to check its thermal stability. The TGA curve of 1 shows two successive steps in the decomposition process. The first step is the loss of the guest ethanol, guest water and coordinated water molecules from 45 to 120 °C (found: 18.57%; calcd: 18.35%). The residual framework starts to decompose at 340 °C and decomposes completely at about 560 °C. The remaining residue is presumed to be ZnO (found: 28.15%; calcd: 29.07%). In summary, we have successfully demonstrated a sandwich framework with (3, 4, 10)-connected topology, in which {Zn}3 cluster is viewed as 10-connected node, while Zn3 and Zn1 atoms are viewed as 3- and 4-connected nodes. The intrinsic value of the present research lies in use of multidentate ligand to induce metal ions into polynuclear metal cluster. Hence, it is believed that this study will lead to the discovery of a large variety of new trinodal highconnected topological structures and types in the near future.
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
Acknowledgment This work was supported by the NSF of China (21071027, 20771023), the China High-Tech Development 863 Program (2007AA03Z218) and Analysis and Testing Foundation of Northeast Normal University.
[7]
Appendix A. Supplementary data CCDC- 800276 contains the supplementary crystallographic data for 1. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/conts/ retrieving.html. Supplementary data to this article can be found online at doi:10. 1016/j.inoche.2011.08.027.
[8]
References [1] (a) O.R. Evans, W.B. Lin, Crystal Engineering of NLO Materials Based on MetalOrganic Coordination Networks, Accounts of Chemical Research 35 (2002) 511–522; (b) S.C. Xiang, X.T. Wu, J.J. Zhang, R.B. Fu, S.M. Hu, X.D. Zhang, A 3D Canted Antiferromagnetic Porous Metal-Organic Framework with Anatase Topology through Assembly of an Analogue of Polyoxometalate, Journal of the American Chemical Society 127 (2005) 16352–16353; (c) S.R. Batten, R. Robson, Interpenetrating Nets: Ordered, Periodic Entanglement, Angewandte Chemie, International Edition 37 (1998) 1460–1494. [2] (a) L.-F. Ma, L.-Y. Wang, M. Du, S.R. Batten, Unprecedented 4- and 6-Connected 2D Coordination Networks Based on 44-Subnet Tectons, Showing Unusual Supramolecular Motifs of Rotaxane and Helix, Inorganic Chemistry 49 (2010) 365–367; (b) J.V. Smith, Topochemistry of Zeolites and Related Materials. 1. Topology and Geometry, Chemical Reviews 88 (1988) 149–182. [3] (a) N.W. Ockwig, O. Delgado-Friedrichs, M. O'Keefee, O.M. Yaghi, Reticular Chemistry: Occurrence and Taxonomy of Nets and Grammar for the Design of Frameworks, Accounts of Chemical Research 38 (2005) 176–182; (b) B.F. Abrahams, S.R. Batten, H. Hamit, B.F. Hoskins, R. Robson, A Cubic (3,4)Connected Net with Large Cavities in Solvated [Cu3(tpt)4](ClO4)3 (tpt = 2,4,6-Tri(4-pyridyl)-1,3,5-triazine), Angewandte Chemie, International Edition 35 (1996) 1690–1692; (c) S.R. Batten, B.F. Hoskins, R. Robson, 3D Knitting patterns. Two independent, interpenetrating rutile-related infinite frameworks in the structure of Zn[C (CN)3]2, Journal of the Chemical Society, Chemical Communications (1991) 445–447. [4] (a) L.-P. Zhang, J.-F. Ma, J. Yang, Y.-Y. Pang, J.-C. Ma, Series of 2D and 3D Coordination Polymers Based on 1,2,3,4-Benzenetetracarboxylate and N-Donor Ligands: Synthesis, Topological Structures, and Photoluminescent Properties, Inorganic Chemistry 49 (2010) 1535–1550; (b) H.-Y. Bai, J.-F. Ma, J. Yang, L.-P. Zhang, J.-C. Ma, Y.-Y. Liu, Eight TwoDimensional and Three-Dimensional Metal-Organic Frameworks Based on a Flexible Tetrakis(imidazole) Ligand: Synthesis, Topological Structures, and Photoluminescent Properties, Crystal Growth and Design 10 (2010) 1946–1959; (c) Y.-R. Liu, L. Li, T. Yang, X.-W. Yua, C.-Y. Su, Dehydration and rehydration behavior of a trinodal topological 3-D framework of Cd(II) benzimidazole-5,6dicarboxylate, CrystEngComm 11 (2009) 2712–2718. [5] (a) Y.-Q. Lan, X.-L. Wang, S.-L. Li, Z.-M. Su, K.-Z. Shao, E.-B. Wang, An unprecedented (6,8)-connected self-penetrating network based on two distinct zinc clusters, Chemical Communications (2007) 4863–4865; (b) Q.-G. Zhai, C.-Z. Lu, X.-Y. Wu, S.R. Batten, Coligand Modulated Six-, Eight-, and Ten-Connected Zn/Cd-1,2,4-Triazolate Frameworks Based on Mono-, Bi-, Tri-, Penta-, and Heptanuclear Cluster Units, Crystal Growth and Design 7 (2007) 2332–2342; (c) Y.-Q. Lan, S.-L. Li, K.-Z. Shao, X.-L. Wang, D.-Y. Du, Z.-M. Su, D.-J. Wang, A (3,12)-Connected 3D Metal-Organic Framework Based on Nanosized Octanuclear Zinc Clusters, Crystal Growth and Design 8 (2008) 3490–3492. [6] (a) X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, Y.-G. Li, L. Xu, Self-Assembly of Nanometer-Scale [Cu24I10L12]14+ Cages and Ball-Shaped Keggin Clusters into a (4,12)-Connected 3D Framework with Photoluminescent and Electrochemical Properties, Angewandte Chemie, International Edition 45 (2006) 7411–7414;
[9]
[10]
[11]
[12]
[13]
[14]
1879
(b) X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, L. Xu, S.R. Batten, An unprecedented eight-connected self-penetrating network based on pentanuclear zinc cluster building blocks, Chemical Communications (2005) 4789–4791. (a) H. Furukawa, J. Kim, K.E. Plass, O.M. Yaghi, Crystal Structure, Dissolution, and Deposition of a 5nm Functionalized Metal Organic Great Rhombicuboctahedron, Journal of the American Chemical Society 128 (2006) 8398–8399; (b) R. Sun, S.N. Wang, H. Xing, J.F. Bai, Y.Z. Li, Y. Pan, X.Z. You, Unprecedented 4264 Topological 2-D Rare-Earth Coordination Polymers from a Flexible Tripodal Acid with Additional Amide Groups, Inorganic Chemistry 46 (2007) 8451–8453; (c) J. Wang, Z.J. Lin, Y.C. Ou, N.L. Yang, Y.H. Zhang, M.L. Tong, Hydrothermal Synthesis, Structures, and Photoluminescent Properties of Benzenepentacarboxylate Bridged Networks Incorporating Zinc(II)−Hydroxide Clusters or Zinc(II)−Carboxylate Layers, Inorganic Chemistry 47 (2008) 190–199. [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) : A mixture of Zn(NO3)2·6H2O (0.059 g, 0.2 mmol) and H4bptc (0.033 g, 0.1 mmol) in water-ethanol (2:1 v/v). It was then sealed in a 25 mL Teflon reactor and heated at 120 °C for 72 h. After the sample was cooled to room temperature at a rate 5 °C h− 1, colourless block crystals were obtained. Yield: 64% based on Zn(II) salt. Anal. calcd for C26H27O19Zn3 (%): C, 37.16; H, 3.22. Found: C, 37.01; H, 3.41. IR (KBr, cm− 1): 3421(w), 1593(m), 1487(m), 1382(m), 1287(s), 1199(s), 1157(m), 1090(m), 1039(m), 834(s), 771(s), 713(m), 526(w). UV–vis (λmax, nm): 248, 462 (solid). Crystal data for 1: monoclinic, C2/n, a = 22.9839(9) Å, b = 10.6211(4) Å, c = 27.5720(14) Å, β = 114.2760(10)° V = 6135.6(5) Å3, Z = 8, R(int) = 0.0371, R1 = 0.0306, wR2 = 0.0724, GOF = 1.019. The X-ray intensity data for 1 were collected on a Bruker SMART APEX CCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 273(2)K. The crystal structure was solved by means of Direct Methods and refined employing full-matrix least squares on F2 (SHELXTL-97). All non-hydrogen atoms were refined anisotropically, the hydrogen atoms of organic ligands were located by geometrically. The hydrogen atoms of water molecules were located by finding difference Fourier maps. Crystal data and details of the structure determination for complex 1 are listed in Table S1 and selected bond lengths and angles are listed in the Table S2.Crystal data for 1: monoclinic, C2/ n, a = 22.9839(9) Å, b = 10.6211(4) Å, c = 27.5720(14) Å, β = 114.2760(10)° V = 6135.6(5) Å3, Z = 8, R(int) = 0.0371, R1 = 0.0306, wR2 = 0.0724, GOF = 1.019. The X-ray intensity data for 1 were collected on a Bruker SMART APEX CCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 273(2)K. The crystal structure was solved by means of Direct Methods and refined employing full-matrix least squares on F2 (SHELXTL-97). All non-hydrogen atoms were refined anisotropically, the hydrogen atoms of organic ligands were located by geometrically. The hydrogen atoms of water molecules were located by finding difference Fourier maps. Crystal data and details of the structure determination for complex 1 are listed in Table S1 and selected bond lengths and angles are listed in the Table S2. S.Q. Zang, Y. Su, Y.-Z. Li, J.G. Lin, X.Y. Duan, Q.J. Meng, S. Gao, Four 2D metal–organic networks incorporating Cd-cluster SUBs: hydrothermal synthesis, structures and photoluminescent properties, CrystEngComm 11 (2009) 122–129. Q. Hua, Y. Zhao, G.-C. Xu, M.-S. Chen, Z. Su, K. Cai, W.-Y. Sun, Synthesis, Structures, and Properties of Zinc(II) and Cadmium(II) Complexes with 1,2,4,5-Tetrakis (imidazol-1-ylmethyl)benzene and Multicarboxylate Ligands, Crystal Growth and Design 10 (2010) 2553–2562. D. Tian, Y. Pang, Y.-H. Zhou, L. Guan, H. Zhang, A series of complexes based on biphenyl-2,5,2’,5’-tetracarboxylic acid: syntheses, crystal structures, luminescent and magnetic properties, CrystEngComm 13 (2011) 957–966. (a) X.J. Ke, D.S. Li, J. Zhao, C.X. Meng, X.N. Zhang, Q.F. He, C. Li, Y.Y. Wang, In situ attained CdII-coordination polymer with (3,4,9)-connected topology based on trinuclear CdII clusters, Inorganic Chemistry Communications 13 (2010) 484–487; (b) L.F. Ma, L.Y. Wang, J.L. Hu, Y.Y. Wang, G.P. Yang, Syntheses, Structures, and Photoluminescence of a Series of d10 Coordination Polymers with R-Isophthalate (R = −OH, −CH3, and −C(CH3)3), Crystal Growth and Design 9 (2009) 5334–5342; (c) D.S. Li, M.L. Zhang, J. Zhao, D.J. Wang, P. Zhang, N. Wang, Y.Y. Wang, A novel 3D CdII-coordination framework with helical units in a mixed flexible ligand system: Encapsulating right-handed helical water chains, Inorganic Chemistry Communications 12 (2009) 1027–1030. (a) T.L. Hu, R.Q. Zou, J.R. Li, X.H. Bu, d10 Metal complexes assembled from isomeric benzenedicarboxylates and 3-(2-pyridyl)pyrazole showing 1D chain structures: syntheses, structures and luminescent properties, Dalton Transactions (2008) 1302–1311; (b) X.F. Zhu, H. Zhang, Y.H. Luo, Y. Pang, D. Tian, A novel eight-connected metal–organic replica of CsCl based on heptanuclear zinc clusters, Inorganic Chemistry Communications 14 (2011) 562–565.
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A (3, 4, 10)-connected 3D sandwich-type metal-organic framework with trinuclear zinc(II) cluster and two kinds of discrete zinc(II) ions Sheng-Qi Guo, Dan Tian, Xiang Zheng, Hong Zhang ⁎ Institute of Polyoxometalate Chemistry, Department of Chemistry, Northeast Normal University, Changchun, Jilin 130024, PR China
a r t i c l e
i n f o
Article history: Received 19 June 2011 Accepted 17 August 2011 Available online 13 September 2011 Keywords: Crystal structure Biphenyl-2,5,2',5'-tetracarboxylic acid Topology Photoluminescent
a b s t r a c t A new 3D sandwich-type MOF named [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) (H4bptc = biphenyl2,5,2',5'-tetracarboxylic acid) was obtained by solvothermal reaction, which represents a rare trinodal (3, 4, 10)-connected topology network. Moreover, the thermal stability, UV–vis absorption spectra and photoluminescent properties of 1 have been investigated as well. © 2011 Elsevier B.V. All rights reserved.
Much interest has been directed toward the research of novel materials based on metal-organic frameworks (MOFs), which is driven not only by their exploitable applications as functional materials in many fields but also by their novel topologies [1]. Net topology plays an important role of synthesis and analysis MOFs, which has been the subject of many investigations, with fundamental contributions by A.F. Wells, J.V. Smith and M. O'Keeffe [2]. Consequently, various uninodal network topologies have been realized, such as 4-connected dia, 6-connected pcu, 8connected bcu and even higher-connected nets. On the other hand, some metal-organic frameworks exhibit interesting nets containing more than one type of node, for example, binodal anatase, boracite, PtS, rutile and twisted boracite [3]; trinodal (3, 3, 5)-, (3, 4, 4)- and (3, 4, 5)connected nets, etc. [4]. Compared to these commonly encountered mixed-connected topologies, the development of higher connectivity nets is still in its early stages. In the past few years, Lu's and Su's groups reported a few cases of binodal high-connected topologies in succession, examples of (3, 12), (4, 8), (4, 10) and (6, 8)-connected nets [5]. However, there is a disappointing lack of investigation on trinodal high-connected topologies. We are interested in this area and try our best to explore this field. Recently, polynuclear metal clusters with more coordination sites are effectively used as nodes for the constructions of higher-connected topologies due to their large surface areas which are beneficial to accommodate the steric demands of organic linkers [6]. Borrowing ideas from polycarboxylate-metal coordination chemistry [7], adjacent “dense” carboxyl groups reacting with metal ions can form various coordination modes and have the high potential to generate novel
⁎ Corresponding author. Tel.: + 86 431 85099370; fax: + 86 431 85099372. E-mail address: [email protected] (H. Zhang). 1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2011.08.027
metal cluster, which all favor to produce MOFs with fascinating and novel topologies. So we choose biphenyl-2,5,2',5'-tetracarboxylic acid (H4bptc) ligand to prepare the complex. Fortunately, a new 3D coordination polymer [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) (H4bptc = biphenyl-2,5,2',5'-tetracarboxylic acid) is successfully isolated by solvothermal method [8]. Complex 1 represents an interesting sandwich framework with a rare (3, 4, 10)-connected topology. Single crystal X-ray diffraction analysis shows [9] that 1 crystallizes in monoclinic space group C2/c. The structure contains four crystallographically independent Zn(II) ions. As shown in Fig. 1a, Zn1 atom is ligated to four carboxylate oxygen atoms from three different bptc 4− ligands, and exists in a distorted tetrahedral environment. Zn2 atom adopts an octahedral geometry which is completed by six carboxylate oxygen atoms from four different bptc4− ligands. Both Zn3 and Zn4 atoms are five-coordinated surrounded by three carboxylate oxygen atoms from three different bptc 4− ligands and two coordinated water molecules, but exhibit different coordination geometries. Zn3 atom is in a trigonal-bipyramid geometry (τ = 0.640) and Zn4 atom exhibits a distorted square-pyramidal geometry (τ =0.488). The Zn–O bond lengths are in the range of 1.938(2) to 2.2577(18) Å. Interestingly, each Zn2 atom is bridged to two neighboring Zn4 atoms by two –O–C–O– bridges and four μ2-Ocarboxyl atoms to afford a {Zn}3 cluster with a Zn2···Zn4 distance of 3.228 Å. The {Zn}3 clusters are further connected through the bptc4− ligands, Zn1 and Zn3 atoms to form a 3D network. To the best of our knowledge, the simultaneous presence of polynuclear metal cluster and two kinds of discrete metal ions in metal organic framework is rather rare [10]. It is worth noting that bptc 4− ligands show two types of coordination modes (Fig. 1b) in complex 1. The μ7-bridged ligand (Mode I) links two {Zn}3 clusters, two Zn3 atoms and one Zn1 atom. Both carboxylic groups of the Mode I ligand exhibit μ2-η 1:η 1 bridging
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
1877
Fig. 1. (a) Coordination environments of the Zn(II) ions in 1. Hydrogen atoms are omitted for clarity. Symmetry codes: A, −x, 1− y, −z; B, ½− x, 1/2− y, −z; C, −1/2 +x, 1/2 −y, −1/2 +z; D, −x, y, −1/2 −z; E, 1/2− x, 1/2+ y, 1/2− z; F, x, 1− y, 1/2+ z; G, x, 1 − y, −1/2+ z; H, 1− x, y, 1/2− z. (b) The coordination modes of two types of bptc4− ligands in 1.
coordination mode, 2-, 2′-carboxylic groups are in syn-anti conformation, while 5-, 5′-carboxylic groups are in syn-syn conformation. The μ6-bridged ligand (Mode II) connects two Zn3 atoms, one {Zn}3
Fig. 2. Perspective views of (a) the 3-connected Zn3 atom, (b) the 4-connected Zn1 atom and (c) the 10-connected {Zn}3 cluster in 1.
cluster and one Zn1 atom, and 2-, 5-, 2′-, 5′-carboxylic groups of the Mode II ligand exhibit μ3-η1:η2, μ1-η 1:η 0, μ2-η 2:η 0, μ1-η1:η 0 coordination modes, respectively. As a result, each {Zn}3 cluster is surrounded by ten discrete Zn atoms (four Zn1 atoms and six Zn3 atoms), which can be simplified as a 10-connected node (Fig. 2c). Similarly, each Zn1 atom connects four {Zn}3 clusters, and Zn3 atom connects three, respectively, which serve as 4- and 3-connected nodes (Fig. 2b, a). The overall structure of 1 is a 3D (3, 4, 10)-connected framework with the Schläfli symbol of (42·6)2(44·62)(4 16·622·86·10) (Fig. 3d). Offering further insight into the nature of this intricate architecture, each {Zn}3 cluster links four neighboring Zn1 atoms to form a 2D layer (Fig. 3a), which can be described as a 44·62 net (Fig. 3c) in the bc plane. Adjacent 2D layers are further pillared by the Zn3 atoms to furnish a 3D polymer with an extremely ordered sandwich-type framework (Fig. 3b). So the topological net of 1 is changed from 4-connected 44·62 net to a rare trinodal (3, 4, 10)-connected net (Fig. 3d). Among the nets based on polynuclear metal cluster, one trinodal (3, 4, 10)-connected net named [Cd3(L)2(BTA)2(H2O)2]·3H2O [11] (L = 1,2,4,5-tetrakis (imidazol-1-ylmethyl)benzene; H3BTA = 1,3,5-benzenetriacetic acid) with the Schläfli symbol of (42·6)2(44·62)(4 16·622·87) has been reported. By contrast, both of two networks view trinuclear metal cluster as the 10-connected node, but two kinds of multidentate ligands were considered as two low-connected nodes in the reported one. Furthermore, although two topologies have similar symbol and three kinds of nodes in the same proportion relationship, we locate a longer 10member loop in complex 1, which is not observed in the reported one. Therefore, the net in 1 represents not only an inimitable sandwichtype structure but also a unique (3, 4, 10) topology.
1878
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
Fig. 3. (a) Polyhedral view of 2D layer formed by {Zn}3 clusters, Zn1 atoms and bptc4− ligands. (b) Polyhedral view of 3D framework of 1 along the b axis. (c) Schematic description of the 2D 44·62 net of 1. (d) Schematic representation of the trinodal (3, 4, 10)-connected 3D network with (42·6)2(44·62)(416·622·86·10) topology for 1.
In the IR spectrum of the pure complex 1 (Supplementary Fig. S1), the absorption bands resulting from the skeletal vibrations of the aromatic ring are observed in the 1400–1600 cm− 1 region. Complex 1 shows the absorption νas(COO) bands at 1595 cm− 1 and νs(COO) bands at 1381 cm− 1, respectively. In comparison to the free H4bptc organic ligand (Fig. S2), the disappearance of a band at 1689 cm− 1 for 1 is indicative of the full deprotonation of H4bptc. These results are also confirmed by single-crystal structure analysis. The peaks at 3861–3421 cm− 1 for the spectra of 1 can be attributed to the O–H stretch of lattice and coordinated water molecules. The solid-state UV–vis spectra at room temperature of complex 1 is displayed in Fig. S3, complex 1 exhibits strong absorption band at
Fig. 4. The emission spectra of 1 (the excitation wavelength were 277 and 350 nm, respectively) and free H4bptc ligand at room temperature.
248 nm with a weak broad band at 462 nm, tentatively arising from intraligand charge transfer transitions. The photoluminescent properties of the free H4bptc ligand and complex 1 at room temperature are depicted in Fig. 4. The H4bptc ligand displays emission peak at 439 nm upon excitation at 377 nm. Excitation spectrum of complex 1 shows two obvious peaks at 277 and 350 nm (Fig. S4), which yield the emission peaks at 389 and 454 nm, respectively. Since it is difficult to oxidize or reduce the Zn(II) cation due to its d 10 configuration [12], the observed emission for 1 is neither metal-to-ligand charge transfer (MLCT) nor ligand-tometal charge transfer (LMCT). It is probably due to the intraligand (π–π*) fluorescent emissions [13]. Comparing with the free H4bptc ligand, the significantly shifted emission maxima for 1 should be assigned to the deprotonation of the H4bptc ligand and the influence of the coordination of the ligand to metal ions [14]. Thermogravimetric (TG) analysis (Fig. S5) of complex 1 is carried out from room temperature to 800 °C under a nitrogen atmosphere so as to check its thermal stability. The TGA curve of 1 shows two successive steps in the decomposition process. The first step is the loss of the guest ethanol, guest water and coordinated water molecules from 45 to 120 °C (found: 18.57%; calcd: 18.35%). The residual framework starts to decompose at 340 °C and decomposes completely at about 560 °C. The remaining residue is presumed to be ZnO (found: 28.15%; calcd: 29.07%). In summary, we have successfully demonstrated a sandwich framework with (3, 4, 10)-connected topology, in which {Zn}3 cluster is viewed as 10-connected node, while Zn3 and Zn1 atoms are viewed as 3- and 4-connected nodes. The intrinsic value of the present research lies in use of multidentate ligand to induce metal ions into polynuclear metal cluster. Hence, it is believed that this study will lead to the discovery of a large variety of new trinodal highconnected topological structures and types in the near future.
S.-Q. Guo et al. / Inorganic Chemistry Communications 14 (2011) 1876–1879
Acknowledgment This work was supported by the NSF of China (21071027, 20771023), the China High-Tech Development 863 Program (2007AA03Z218) and Analysis and Testing Foundation of Northeast Normal University.
[7]
Appendix A. Supplementary data CCDC- 800276 contains the supplementary crystallographic data for 1. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/conts/ retrieving.html. Supplementary data to this article can be found online at doi:10. 1016/j.inoche.2011.08.027.
[8]
References [1] (a) O.R. Evans, W.B. Lin, Crystal Engineering of NLO Materials Based on MetalOrganic Coordination Networks, Accounts of Chemical Research 35 (2002) 511–522; (b) S.C. Xiang, X.T. Wu, J.J. Zhang, R.B. Fu, S.M. Hu, X.D. Zhang, A 3D Canted Antiferromagnetic Porous Metal-Organic Framework with Anatase Topology through Assembly of an Analogue of Polyoxometalate, Journal of the American Chemical Society 127 (2005) 16352–16353; (c) S.R. Batten, R. Robson, Interpenetrating Nets: Ordered, Periodic Entanglement, Angewandte Chemie, International Edition 37 (1998) 1460–1494. [2] (a) L.-F. Ma, L.-Y. Wang, M. Du, S.R. Batten, Unprecedented 4- and 6-Connected 2D Coordination Networks Based on 44-Subnet Tectons, Showing Unusual Supramolecular Motifs of Rotaxane and Helix, Inorganic Chemistry 49 (2010) 365–367; (b) J.V. Smith, Topochemistry of Zeolites and Related Materials. 1. Topology and Geometry, Chemical Reviews 88 (1988) 149–182. [3] (a) N.W. Ockwig, O. Delgado-Friedrichs, M. O'Keefee, O.M. Yaghi, Reticular Chemistry: Occurrence and Taxonomy of Nets and Grammar for the Design of Frameworks, Accounts of Chemical Research 38 (2005) 176–182; (b) B.F. Abrahams, S.R. Batten, H. Hamit, B.F. Hoskins, R. Robson, A Cubic (3,4)Connected Net with Large Cavities in Solvated [Cu3(tpt)4](ClO4)3 (tpt = 2,4,6-Tri(4-pyridyl)-1,3,5-triazine), Angewandte Chemie, International Edition 35 (1996) 1690–1692; (c) S.R. Batten, B.F. Hoskins, R. Robson, 3D Knitting patterns. Two independent, interpenetrating rutile-related infinite frameworks in the structure of Zn[C (CN)3]2, Journal of the Chemical Society, Chemical Communications (1991) 445–447. [4] (a) L.-P. Zhang, J.-F. Ma, J. Yang, Y.-Y. Pang, J.-C. Ma, Series of 2D and 3D Coordination Polymers Based on 1,2,3,4-Benzenetetracarboxylate and N-Donor Ligands: Synthesis, Topological Structures, and Photoluminescent Properties, Inorganic Chemistry 49 (2010) 1535–1550; (b) H.-Y. Bai, J.-F. Ma, J. Yang, L.-P. Zhang, J.-C. Ma, Y.-Y. Liu, Eight TwoDimensional and Three-Dimensional Metal-Organic Frameworks Based on a Flexible Tetrakis(imidazole) Ligand: Synthesis, Topological Structures, and Photoluminescent Properties, Crystal Growth and Design 10 (2010) 1946–1959; (c) Y.-R. Liu, L. Li, T. Yang, X.-W. Yua, C.-Y. Su, Dehydration and rehydration behavior of a trinodal topological 3-D framework of Cd(II) benzimidazole-5,6dicarboxylate, CrystEngComm 11 (2009) 2712–2718. [5] (a) Y.-Q. Lan, X.-L. Wang, S.-L. Li, Z.-M. Su, K.-Z. Shao, E.-B. Wang, An unprecedented (6,8)-connected self-penetrating network based on two distinct zinc clusters, Chemical Communications (2007) 4863–4865; (b) Q.-G. Zhai, C.-Z. Lu, X.-Y. Wu, S.R. Batten, Coligand Modulated Six-, Eight-, and Ten-Connected Zn/Cd-1,2,4-Triazolate Frameworks Based on Mono-, Bi-, Tri-, Penta-, and Heptanuclear Cluster Units, Crystal Growth and Design 7 (2007) 2332–2342; (c) Y.-Q. Lan, S.-L. Li, K.-Z. Shao, X.-L. Wang, D.-Y. Du, Z.-M. Su, D.-J. Wang, A (3,12)-Connected 3D Metal-Organic Framework Based on Nanosized Octanuclear Zinc Clusters, Crystal Growth and Design 8 (2008) 3490–3492. [6] (a) X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, Y.-G. Li, L. Xu, Self-Assembly of Nanometer-Scale [Cu24I10L12]14+ Cages and Ball-Shaped Keggin Clusters into a (4,12)-Connected 3D Framework with Photoluminescent and Electrochemical Properties, Angewandte Chemie, International Edition 45 (2006) 7411–7414;
[9]
[10]
[11]
[12]
[13]
[14]
1879
(b) X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, L. Xu, S.R. Batten, An unprecedented eight-connected self-penetrating network based on pentanuclear zinc cluster building blocks, Chemical Communications (2005) 4789–4791. (a) H. Furukawa, J. Kim, K.E. Plass, O.M. Yaghi, Crystal Structure, Dissolution, and Deposition of a 5nm Functionalized Metal Organic Great Rhombicuboctahedron, Journal of the American Chemical Society 128 (2006) 8398–8399; (b) R. Sun, S.N. Wang, H. Xing, J.F. Bai, Y.Z. Li, Y. Pan, X.Z. You, Unprecedented 4264 Topological 2-D Rare-Earth Coordination Polymers from a Flexible Tripodal Acid with Additional Amide Groups, Inorganic Chemistry 46 (2007) 8451–8453; (c) J. Wang, Z.J. Lin, Y.C. Ou, N.L. Yang, Y.H. Zhang, M.L. Tong, Hydrothermal Synthesis, Structures, and Photoluminescent Properties of Benzenepentacarboxylate Bridged Networks Incorporating Zinc(II)−Hydroxide Clusters or Zinc(II)−Carboxylate Layers, Inorganic Chemistry 47 (2008) 190–199. [Zn3(bptc)1.5(H2O)4]·C2H5OH·2H2O (1) : A mixture of Zn(NO3)2·6H2O (0.059 g, 0.2 mmol) and H4bptc (0.033 g, 0.1 mmol) in water-ethanol (2:1 v/v). It was then sealed in a 25 mL Teflon reactor and heated at 120 °C for 72 h. After the sample was cooled to room temperature at a rate 5 °C h− 1, colourless block crystals were obtained. Yield: 64% based on Zn(II) salt. Anal. calcd for C26H27O19Zn3 (%): C, 37.16; H, 3.22. Found: C, 37.01; H, 3.41. IR (KBr, cm− 1): 3421(w), 1593(m), 1487(m), 1382(m), 1287(s), 1199(s), 1157(m), 1090(m), 1039(m), 834(s), 771(s), 713(m), 526(w). UV–vis (λmax, nm): 248, 462 (solid). Crystal data for 1: monoclinic, C2/n, a = 22.9839(9) Å, b = 10.6211(4) Å, c = 27.5720(14) Å, β = 114.2760(10)° V = 6135.6(5) Å3, Z = 8, R(int) = 0.0371, R1 = 0.0306, wR2 = 0.0724, GOF = 1.019. The X-ray intensity data for 1 were collected on a Bruker SMART APEX CCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 273(2)K. The crystal structure was solved by means of Direct Methods and refined employing full-matrix least squares on F2 (SHELXTL-97). All non-hydrogen atoms were refined anisotropically, the hydrogen atoms of organic ligands were located by geometrically. The hydrogen atoms of water molecules were located by finding difference Fourier maps. Crystal data and details of the structure determination for complex 1 are listed in Table S1 and selected bond lengths and angles are listed in the Table S2.Crystal data for 1: monoclinic, C2/ n, a = 22.9839(9) Å, b = 10.6211(4) Å, c = 27.5720(14) Å, β = 114.2760(10)° V = 6135.6(5) Å3, Z = 8, R(int) = 0.0371, R1 = 0.0306, wR2 = 0.0724, GOF = 1.019. The X-ray intensity data for 1 were collected on a Bruker SMART APEX CCD diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 273(2)K. The crystal structure was solved by means of Direct Methods and refined employing full-matrix least squares on F2 (SHELXTL-97). All non-hydrogen atoms were refined anisotropically, the hydrogen atoms of organic ligands were located by geometrically. The hydrogen atoms of water molecules were located by finding difference Fourier maps. Crystal data and details of the structure determination for complex 1 are listed in Table S1 and selected bond lengths and angles are listed in the Table S2. S.Q. Zang, Y. Su, Y.-Z. Li, J.G. Lin, X.Y. Duan, Q.J. Meng, S. Gao, Four 2D metal–organic networks incorporating Cd-cluster SUBs: hydrothermal synthesis, structures and photoluminescent properties, CrystEngComm 11 (2009) 122–129. Q. Hua, Y. Zhao, G.-C. Xu, M.-S. Chen, Z. Su, K. Cai, W.-Y. Sun, Synthesis, Structures, and Properties of Zinc(II) and Cadmium(II) Complexes with 1,2,4,5-Tetrakis (imidazol-1-ylmethyl)benzene and Multicarboxylate Ligands, Crystal Growth and Design 10 (2010) 2553–2562. D. Tian, Y. Pang, Y.-H. Zhou, L. Guan, H. Zhang, A series of complexes based on biphenyl-2,5,2’,5’-tetracarboxylic acid: syntheses, crystal structures, luminescent and magnetic properties, CrystEngComm 13 (2011) 957–966. (a) X.J. Ke, D.S. Li, J. Zhao, C.X. Meng, X.N. Zhang, Q.F. He, C. Li, Y.Y. Wang, In situ attained CdII-coordination polymer with (3,4,9)-connected topology based on trinuclear CdII clusters, Inorganic Chemistry Communications 13 (2010) 484–487; (b) L.F. Ma, L.Y. Wang, J.L. Hu, Y.Y. Wang, G.P. Yang, Syntheses, Structures, and Photoluminescence of a Series of d10 Coordination Polymers with R-Isophthalate (R = −OH, −CH3, and −C(CH3)3), Crystal Growth and Design 9 (2009) 5334–5342; (c) D.S. Li, M.L. Zhang, J. Zhao, D.J. Wang, P. Zhang, N. Wang, Y.Y. Wang, A novel 3D CdII-coordination framework with helical units in a mixed flexible ligand system: Encapsulating right-handed helical water chains, Inorganic Chemistry Communications 12 (2009) 1027–1030. (a) T.L. Hu, R.Q. Zou, J.R. Li, X.H. Bu, d10 Metal complexes assembled from isomeric benzenedicarboxylates and 3-(2-pyridyl)pyrazole showing 1D chain structures: syntheses, structures and luminescent properties, Dalton Transactions (2008) 1302–1311; (b) X.F. Zhu, H. Zhang, Y.H. Luo, Y. Pang, D. Tian, A novel eight-connected metal–organic replica of CsCl based on heptanuclear zinc clusters, Inorganic Chemistry Communications 14 (2011) 562–565.