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Unusual metal-organic frameworks built from 2D layers through Cl⋯Cl contacts and hydrogen bonds
Inorganic Chemistry Communications 10 (2007) 362–366 www.elsevier.com/locate/inoche
Unusual metal-organic frameworks built from 2D layers through Cl Cl contacts and hydrogen bonds Hai-Bin Zhu, Zhao-Lian Chu, Da-Hua Hu, Wei Huang, Shao-Hua Gou
*
School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China Received 29 October 2006; accepted 24 November 2006 Available online 8 December 2006
Abstract Unusual metal-organic frameworks [M(dtcp)2](SCN)2 [M = Zn, Mn; dtcp = 2,6-di(1,2,4-triazol-1-ylmethyl)-4-chlorophenol] are composed of 2D rhombus-type grid networks associated mutually by remarkable Cl Cl contacts and hydrogen bonds (C–H N and C– H S). Both thermogravimetric analysis and photoluminescence measurements are performed as well to characterize these supramolecular frameworks. Ó 2006 Elsevier B.V. All rights reserved. Keywords: MOFs; Hydrogen bond; 1, 2, 4-Triazole; Chlorine
There is continuous interest in the design of metalorganic frameworks (MOFs), which comes not only from their great potential as functional materials but also their attractive variety of structures and topologies [1,2]. Nevertheless, the precise control of the structure associated with the expected properties still remains a challenge to chemists in that the formation of MOFs is subject to various factors such as solvent systems and counterions as well as the nature of metal ions [3]. Within this realm, the rational combination of well-defined organic linkers with suitable metal ions via coordination bonds has been well established as one of the best strategies for the construction of MOFs, which permits to direct and control the outcome to some extent. However, such subtle noncovalent interactions as hydrogen bonding, aromatic stacking and diverse short contacts may modify, and even distort the predicted structures. At the same time, such weak interactions, on the other hand, provide extra opportunities to produce supramolecular architectures of the highest dimensions such as hydrogen-bonded interpenetrating networks [4].
*
Corresponding author. Tel.: +86 25 83595068; fax: +86 25 83686253. E-mail address: [email protected] (S.-H. Gou).
1387-7003/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2006.11.015
Over the past decade, organic ligands with azole units (e.g. pyrazole, imidazole, and triazole) have become a new class of supramolecular synthon of intense interest in creating plentiful appealing MOFs [5–9]. As far as we know, most of them reported to date have azole units as the exclusive functional groups, and thus a majority of noncovalent interactions involved in crystal structures hinge largely on azole-based N atoms. However, from the crystallographic point of view, it is reasonable to believe that the final assembled structure may be changed dramatically provided that different functional groups, implying distinct noncovalent interactions, are incorporated into these azole-containing ligands. In fact, a few of reports have appeared on this aspect. An earlier example was a dimeric structure with the pyrazole-containing organic ligand, dpmp (2,6-bis(pyrazol-1-ylmethyl)-4-methylphenol), wherein each phenol oxygen atom bridged two independent Zn2+ ions [10]. Moreover, we previously reported a 1D neutral chain assembled from dtmp (2, 6-di(1,2,4-triazol-1-ylmethyl)-4-methylphenol) and CuCl2, in which the noncoordinated phenol group was involved in hydrogen bonding, O–H Cl [11]. Another recent example was from the reaction of bib (2,6-di(imdazol-1-ylmethyl)4-bromophenol) with Zn(OAc)2, which generated the first example of
H.-B. Zhu et al. / Inorganic Chemistry Communications 10 (2007) 362–366
1D pseudo polyrotaxane mediated by Br Br interactions [12] (Fig. 1). As the extension of our previous study [11], a new triazole-containing organic linker, dtcp (2,6-di(1,2,4-triazol-1ylmethyl)-4-chlorophenol), has been synthesized [13], in which the chloro-group instead of methyl group is introduced by a sharp contrast with dtmp (Fig. 1). As a consequence, noncovalent interactions involving both chloroand phenol-groups can be expected in the assembly progress, which may lead to complexes with a novel structure and topology. Br N
N
N
N
N
N N
N
OH dpmp
bib Cl N
N
N
N
N
N
N N
N OH
N N
OH N dtmp
dtcp
Fig. 1. Schematic drawings of azole-containing organic ligands: dpmp, bib, dtmp and dtcp.
363
In this paper, we report unprecedented metal-organic frameworks [Zn(dtcp)2](SCN)2 (1) and [Mn(dtcp)2](SCN)2 (2), which are prepared by the reactions of dtcp with Zn(NO3)2 and MnCl2 in the presence of excess NH4SCN [14]. In particular, X-ray crystallographic analysis [15] reveals that these MOFs are built from 2D layers mediated by Cl Cl contacts and hydrogen bonds. Both compounds are isostructural with the same formula [M(dtcp)2](SCN)2, and the major difference lies in the nature of the metal ions [(1) M = Zn; (2) M = Mn]. As a result, both complexes are structurally similar to each other. The typical crystal structure of complex 1 is depicted in Fig. 2. Clearly, each Zn2+ ion in complex 1 is six-coordinated, equatorially by four dtcp ligands and axially by two SCN ions. Each ligand is bound to the metal atom in exo N atom, whereas the SCN ion acts as an N-bound monodentate ligand, which is almost linear. The Zn–N ˚ . The bond lengths are within the range of 2.13–2.18 A 2+ Zn ion sits on the crystallographic inversion center and the coordination geometry around the metal atom is a slightly distorted octahedron. As depicted in Fig. 3, each dtcp ligand in complex 1 connects two zinc atoms to build up a M4L4 metallocyclic ring in trans conformation, which differs from the cis mode for dtmp [11]. Two triazole units in each ligand with regard to the central phenyl ring make dihedral angles of 74.7o and 58.3o, respectively. In such a M4L4 metallocycle, those 1,3-alternate phenyl rings are parallel to each other, whereas 1,2-alternate ones make a dihedral angle of 56.5o. The polymeric structure of 1 consists of 2D flat
˚ ) and bond angles (°): Complex Fig. 2. Crystal structure of complex 1 drawn at 50% probability with the atom-numbering scheme. Selected bond length (A 1 Zn1–N1 2.1821(19), Zn1–N7 2.133(2), Zn1–N4 2.155(2), N1–Zn1–N7 91.50(8), N1–Zn1–N4 91.53(7), N1–Zn1–N7A 88.50(8), N4–Zn1–N7 90.82(8), N1–Zn1–N4A 88.47(7), S1–C13–N7 179.6(2); Complex 2: Mn1–N1 2.275(3), Mn1–N7 2.184(3), N1–Mn1–N7 92.15(10), N1–Mn1–N4A 87.93(9), N1– Mn1–N7C 87.85(10), N1–Mn1–N4D 92.07(9), S1–C13–N7 179.3(3).
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˚ ; complex 2: dO–N = 2.882(3) A ˚ ]. (For interpretation of Fig. 3. 2D polymeric structure of complex 1 [O–H N(dashed line): complex 1: dO–N = 2.888(3) A the references in colour in this figure legend, the reader is referred to the web version of this article.)
rhombus-type grid networks with each grid side having a ˚ . Similarly, each ligand in complex 2 links length of 13.47 A two Mn2+ ions in the trans conformation to form a M4L4 metallocyclic ring, which is further assembled into a 2D rhombus-type grid network via Mn–N coordination bonds ˚ long. Unlike the situations in and each grid side is 13.59 A dpmp and dtmp [10,11], it is worthy to note that the phenol group of dtcp ligand in these complexes is involved in the intramolecular hydrogen bond O–H N in the resulted 2D flat layer. In complexes 1 and 2, the 2D layers are organized parallel to the crystallographic a b plane with the interplanar ˚ and 5.01 A ˚ , respectively. The space distance of 4.99 A between the neighboring layers is occupied by the coordinated SCN groups. Especially, adjacent layers are arranged in an offset manner to place the metal atoms of one layer right above the centers of rhombus-type grids of the other (Fig. 4), which is comparable with the example of double
layers in Cu(II) complexes with 1,3-bis(1,2,4-triazol-1yl)propane [8]. Additionally, these 2D layers interplay weakly each other via various noncovalent interactions. For complex 1, the adjoining layers are associated together by hydrogen bond interactions (a), C1–H1 N3. In contrast, the separated layers A1–A2 (B1–B2) interact mutually via hydrogen bonds (b), C–H S, which exactly interpenetrate the void of rhombus-type grids in the intermediate layer B1 (A2). Strikingly, layers (A1–B2) with a double interplanar separation are further stabilized by remarkable Cl Cl contacts (c), which also pass through the grid cavities of the two middle layers (B1 and A2). Likewise, such noncovalent interactions as those in complex 1 are found as well in complex 2. Directional interactions between halogens, which are due to specific attractive forces [16], have been known for their wide application in systematic crystal engineering [17]. For the azole-containing organic ligand, a 1D pseudo polyrotaxane promoted A1
d M-M
a B1
a b
c
A2
dM-M
a
b
B2
M = Zn, Mn A B ˚ , symmetry code: x, 1/2 y, 1/ Fig. 4. Schematic showing noncovalent interactions between 2D flat layers. Complex 1 a: C1–H1 N3: dC1–N3 = 3.333(3) A ˚ , symmetry code: x, y, 1 + z; C12–H12 S1: dC12–S1 = 3.721(2) A ˚ , symmetry code: x, y, 1+z. c: Cl Cl 2 + z. b: C6–H6A S1: dC6–S1 = 3.739(2) A ˚ ). Complex 2 (a): C2–H2 N2: dC2–N2 = 3.370(4) A ˚ , symmetry code: x, 1/2 y, 1/2 + z; (b) C10–H10B S1: dC10– contacts (dashed lines, dCl Cl = 3.37 A ˚ ˚ S1 = 3.752(4) A, symmetry code: 1 + x, 1/2 y, 1/2 + z; (c) Cl Cl contacts (dCl Cl = 3.49 A).
H.-B. Zhu et al. / Inorganic Chemistry Communications 10 (2007) 362–366
by Br Br interactions was reported in complex [Zn2(bib)2(OAc)4] Æ 2H2O. Conversely, the bromo-group in [Zn(bib)2(H2O)2](NO3)2 Æ 2H2O and [Mn(bib)2(H2O)2](NO3)2 Æ 2H2O was involved neither in the hydrogen bonding nor in Br Br contacts [12]. To the best of our knowledge, it is the first example of MOFs with azole-containing ligands built from 2D flat layers via Cl Cl contacts. The thermal behaviors of complexes 1–2 were measured by using a TGA method under a nitrogen stream. The measurements show that complexes 1 and 2 remain stable up to 191 and 136 °C, respectively. Beyond these temperatures, the organic ligands dtcp are lost, and the complexes are decomposed. The residues at 700 °C for complexes 1 and 2 are 41.4% and 46.1%, respectively. The photoluminescence properties of complexes 1 and 2 were investigated in the solid state at ambient temperature. The measurements were carried out under the same conditions. Complex 1 exhibits luminescence with emission maximum at 468 ± 2 nm upon excitation at 397 nm, which is similar to ligand dtcp (emission maximum at 466 nm upon excitation at 397 nm). The emissions observed in complex 1 is probably from the p–p* intraligand fluorescence because of their close resemblance of the emission bands [6a]. However, no clear photoluminescence was observed for complex 2, which is possibly quenched by Mn(II) ions. In summary, we have obtained novel metal-organic frameworks constructed by 2D flat layers mediated by Cl Cl contacts and hydrogen bonds, which is primarily ascribed to the presence of chloro-group in the dtcp ligand and SCN coordinating ions. Supplementary material CCDC 625277 and 625278 contain the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/ conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2006.11.015.
[2]
[3]
[4]
[5]
[6]
[7]
[8] [9]
[10] [11] [12]
Acknowledgement [13]
The authors are grateful to the financial support by the National Natural Science Foundation of China (Projects 20271026 and 20301009). Thanks are also due to Postdoctoral Research Fund from Jiangsu Province Personnel Department (0502005B) and Postdoctoral Research Fund of China (20060390278) to Dr. Zhu. References [1] (a) W. Huang, H.B. Zhu, S.H. Gou, Coord. Chem. Rev. 250 (2006) 414;
[14]
365
(b) L. Carlucci, G. Ciani, D.M. Proserpio, Coord. Chem. Rev. 246 (2003) 247; (c) M. Eddaoudi, D.B. Moler, H.L. Li, B.L. Chen, T.M. Reineke, M. O’ Keefe, Q.M. Yaghi, Acc. Chem. Res. 34 (2001) 319; (d) S.R. Batten, Curr. Opin. Solid State Mater. Sci. 5 (2001) 107; (e) P.J. Stang, B. Olenyuk, Acc. Chem. Res. 32 (1999) 975. (a) S. Kitagawa, R. Kitaura, S.L. Noro, Angew. Chem. Int. Ed. 43 (2004) 2334; (b) C. Janiak, Dalton Trans. (2003) 2781; (c) M.J. Zaworotko, Chem. Commun. (2001) 1; (d) B.F. Hoskins, R. Robson, D.A. Slizys, J. Am. Chem. Soc. 119 (1997) 2952. (a) L. Carlucci, G. Ciani, P. Macchi, D.M. Proserpio, S. Rizaato, Chem. Eur. J. 5 (1999) 237; (b) J.S. Fleming, K.L.V. Mann, C.A. Carraz, E. Psillakis, J.C. Jeffry, J.A. McCleverty, M.D. Ward, Angew. Chem. Int. Ed. 37 (1998) 1279. (a) M. Du, X.J. Zhao, S.R. Batten, J. Ribas, Cryst. Growth Des. 5 (2005) 901; (b) S.L. Li, J.H. Shao, Y.Z. Zhao, Y.X. Wang, Chin. J. Inorg. Chem. 19 (2003) 1059; (c) Y. Diskin-Posner, G.K. Patra, I. Goldberg, Chem. Commun. (2002) 1420; (d) A.C. Benyei, P.I. Coupar, G. Ferguson, C. Glidewell, A.J. Lough, P.R. Meehan, Acta Crystallogr. Sect. C 54 (1998) 1515. (a) Y.F. Peng, H.Y. Ge, B.Z. Li, B.L. Li, Y. Zhang, Cryst. Growth Des. 6 (2006) 994; (b) B.L. Li, X. Zhu, J.H. Zhou, Y.F. Peng, Y. Zhang, Polyhedron 23 (2004) 3133; (c) J.H. Zhou, Y.F. Peng, Y.P. Zhang, B.L. Li, Y. Zhang, Inorg. Chem. Commun. 7 (2004) 1181; (d) B.L. Li, Y.F. Peng, B.Z. Li, Y. Zhang, Chem. Commun. (2005) 2333. (a) H.F. Zhu, J. Fan, T.A. Okamura, W.Y. Sun, N. Ueyama, Cryst. Growth Des. 5 (2005) 289; (b) B.L. Fei, W.Y. Sun, Y.A. Zhang, K.B. Yu, W.X. Tang, J. Chem. Soc. Dalton Trans. (2000) 2345; (c) B. Sui, J. Fan, T.A. Okamura, W.Y. Sun, N. Ueyama, New. J. Chem. 25 (2001) 1379. (a) Y. Garcia, G. Bravic, C. Gieck, D. Chasseau, W. Tremel, P. Gutlich, Inorg. Chem. 44 (2005) 9723; (b) Y. Garcia, O. Kahn, L. Rabardel, ; B. Chansou, L. Salmon, J.P. Tuchagues, Inorg. Chem. 38 (1999) 4663. G.A. Albada, R.C. Guijt, J.G. Haasnoot, M. Lutz, A.L. Spek, J. Reedijk, Eur. J. Inorg. Chem. (2000) 121. (a) B.F. Hoskins, R. Robson, D.A. Slizys, ; J. Am. Chem. Soc. 119 (1997) 2952; (b) B.F. Hoskins, R. Robson, D.A. Slizys, Angew. Chem. Int. Ed. 36 (1997) 2336. C.T. Chen, W.K. Chang, S.C. Sheu, G.H. Lee, T.I. Ho, Y.C. Lin, Y. Wang, J. Chem. Soc. Dalton Trans. (1991) 1569. H.B. Zhu, C.H. Huang, W. Huang, S.H. Gou, Inorg. Chem. Commun. 7 (2004) 1095. J. Fan, W.Y. Sun, T. Okamura, Y.Q. Zheng, B. Sui, Cryst. Growth Des. 4 (2004) 579. The ligand, dtcp, was prepared according to our formerly reported procedure [11]. Yield: 78%. IR mKBr (cm 1): 3280 m, 3132 m, 3109 m, 1509 m, 1481 m, 1133 m, 1107 m, 681 m, 653 m. 1H NMR (CDCl3 25 °C): d = 10.12 (br, 1H, OH), 8.20 (s, 2H, triazole-H), 7.95 (s, 2H, triazole-H), 7.26 (s, 2H, phenyl-H), 5.31 (s, 4H, –CH2–). Anal. Calc. for C12H11ClN6O: C, 49.58; H, 3.81; N, 28.91. Found: C, 49.51; H, 3.65; N, 28.72. [Zn(dtcp)2](SCN)2 (1). A solution of dtcp (0.2 mmol), Zn(NO3)2 (0.1 mmol) and NH4SCN (0.25 mmol) in 20 ml MeOH was refluxed for 2 h and cooled to room temperature. After filtration, the mother liquid remained at room temperature for three days to give crystals suitable for X-ray analysis. Yield: 72%. IR mKBr (cm 1): 3291 m, 3121 m, 2069 s, 1521 m, 1468 m, 1132 m, 677 m, 6445 m. 1H NMR (DMSO-d6 25°C): d = 9.76 (s, 1H, OH), 8.59 (s, 2H, triazole-H), 7.99
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(s, 2H, triazole-H), 7.04 (s, 2H, phenyl-H), 5.41 (s, 4H, –CH2–). Anal. Calc. for C26H22Cl2ZnN14O2S2: C, 40.93; H, 2.91; N, 25.70. Found: C, 40.80; H, 2.75; N, 25.52. [Mn(dtcp)2](SCN)2 (2). The complex was prepared in a similar procedure to that for complex 1. Yield: 75%. IR mKBr (cm 1): 3278 m, 3110 m, 2057 s, 1520 m, 1483 m, 1133 m, 676 m, 645 m. Anal. Calc. for C26H22Cl2MnN14O2S2: C, 41.50; H, 2.95; N, 26.06. Found: C, 41.54; H, 2.55; N, 25.22. [15] Diffraction intensities for complexes 1 and 2 were collected at 293(2) K on a Bruker SMART CCD-4K diffractometer employing graphite˚ ). The data were monochromated MoKa radiation (k = 0.71073 A collected using SMART and reduced by the program SAINT. All the structures were solved by direct methods and refined by full-matrix least squares method on F 2obs by using SHELXTL-PC software package. Non-hydrogen atoms were placed in geometrically calculated positions. Crystal data for 1: C26H22Cl2ZnN14O2S2, M = 763.01, monoclinic, space group P21/c, a = 11.5288(11), b = 13.316(1), c =
˚ , b = 100.783(1)°, V = 1556.2(3) A ˚ 3, D = 1.628 g cm 3, 10.319(1) A Z = 2, F (0 0 0) = 776. Unique data (Rint) = 2723 (0.060), GOF = 1.04, R1 = 0.0326, wR2 = 0.0889. 2: C26H22Cl2MnN14O2S2, M = 752.56, monoclinic, space group P21/c, a = 11.560(2), ˚ , b = 100.130(3)°, V = 1590.9(5) A ˚ 3, b = 13.428(2), c = 10.411(2) A 3 D = 1.571 g cm , Z = 2, F (0 0 0) = 766. Unique data (Rint) = 2789(0.040), GOF = 1.02, R1 = 0.0481, wR2 = 0.1180. [16] G.R. Desiraju, R. Parthasarathy, J. Am. Chem. Soc. 111 (1989) 8725. [17] (a) A. Matsumoto, T. Tanaka, T. Tsubouchi, K. Tashiro, S. Saragai, S. Nakamoto, J. Am. Chem. Soc. 124 (2002) 8891; (b) J.N. Moorthy, R. Natarajan, P. Mal, P. Venugopalan, J. Am. Chem. Soc. 124 (2002) 6530; (c) K. Tanaka, D. Fujimoto, A. Altreuther, T. Oeser, H. Irngartinger, F. Tode, J. Chem. Soc. Perkin Trans. 2 (2000) 2115; (d) D.S. Reddy, D.C. Craig, G.R. Desiraju, J. Am. Chem. Soc. 118 (1996) 4090.
Unusual metal-organic frameworks built from 2D layers through Cl Cl contacts and hydrogen bonds Hai-Bin Zhu, Zhao-Lian Chu, Da-Hua Hu, Wei Huang, Shao-Hua Gou
*
School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China Received 29 October 2006; accepted 24 November 2006 Available online 8 December 2006
Abstract Unusual metal-organic frameworks [M(dtcp)2](SCN)2 [M = Zn, Mn; dtcp = 2,6-di(1,2,4-triazol-1-ylmethyl)-4-chlorophenol] are composed of 2D rhombus-type grid networks associated mutually by remarkable Cl Cl contacts and hydrogen bonds (C–H N and C– H S). Both thermogravimetric analysis and photoluminescence measurements are performed as well to characterize these supramolecular frameworks. Ó 2006 Elsevier B.V. All rights reserved. Keywords: MOFs; Hydrogen bond; 1, 2, 4-Triazole; Chlorine
There is continuous interest in the design of metalorganic frameworks (MOFs), which comes not only from their great potential as functional materials but also their attractive variety of structures and topologies [1,2]. Nevertheless, the precise control of the structure associated with the expected properties still remains a challenge to chemists in that the formation of MOFs is subject to various factors such as solvent systems and counterions as well as the nature of metal ions [3]. Within this realm, the rational combination of well-defined organic linkers with suitable metal ions via coordination bonds has been well established as one of the best strategies for the construction of MOFs, which permits to direct and control the outcome to some extent. However, such subtle noncovalent interactions as hydrogen bonding, aromatic stacking and diverse short contacts may modify, and even distort the predicted structures. At the same time, such weak interactions, on the other hand, provide extra opportunities to produce supramolecular architectures of the highest dimensions such as hydrogen-bonded interpenetrating networks [4].
*
Corresponding author. Tel.: +86 25 83595068; fax: +86 25 83686253. E-mail address: [email protected] (S.-H. Gou).
1387-7003/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2006.11.015
Over the past decade, organic ligands with azole units (e.g. pyrazole, imidazole, and triazole) have become a new class of supramolecular synthon of intense interest in creating plentiful appealing MOFs [5–9]. As far as we know, most of them reported to date have azole units as the exclusive functional groups, and thus a majority of noncovalent interactions involved in crystal structures hinge largely on azole-based N atoms. However, from the crystallographic point of view, it is reasonable to believe that the final assembled structure may be changed dramatically provided that different functional groups, implying distinct noncovalent interactions, are incorporated into these azole-containing ligands. In fact, a few of reports have appeared on this aspect. An earlier example was a dimeric structure with the pyrazole-containing organic ligand, dpmp (2,6-bis(pyrazol-1-ylmethyl)-4-methylphenol), wherein each phenol oxygen atom bridged two independent Zn2+ ions [10]. Moreover, we previously reported a 1D neutral chain assembled from dtmp (2, 6-di(1,2,4-triazol-1-ylmethyl)-4-methylphenol) and CuCl2, in which the noncoordinated phenol group was involved in hydrogen bonding, O–H Cl [11]. Another recent example was from the reaction of bib (2,6-di(imdazol-1-ylmethyl)4-bromophenol) with Zn(OAc)2, which generated the first example of
H.-B. Zhu et al. / Inorganic Chemistry Communications 10 (2007) 362–366
1D pseudo polyrotaxane mediated by Br Br interactions [12] (Fig. 1). As the extension of our previous study [11], a new triazole-containing organic linker, dtcp (2,6-di(1,2,4-triazol-1ylmethyl)-4-chlorophenol), has been synthesized [13], in which the chloro-group instead of methyl group is introduced by a sharp contrast with dtmp (Fig. 1). As a consequence, noncovalent interactions involving both chloroand phenol-groups can be expected in the assembly progress, which may lead to complexes with a novel structure and topology. Br N
N
N
N
N
N N
N
OH dpmp
bib Cl N
N
N
N
N
N
N N
N OH
N N
OH N dtmp
dtcp
Fig. 1. Schematic drawings of azole-containing organic ligands: dpmp, bib, dtmp and dtcp.
363
In this paper, we report unprecedented metal-organic frameworks [Zn(dtcp)2](SCN)2 (1) and [Mn(dtcp)2](SCN)2 (2), which are prepared by the reactions of dtcp with Zn(NO3)2 and MnCl2 in the presence of excess NH4SCN [14]. In particular, X-ray crystallographic analysis [15] reveals that these MOFs are built from 2D layers mediated by Cl Cl contacts and hydrogen bonds. Both compounds are isostructural with the same formula [M(dtcp)2](SCN)2, and the major difference lies in the nature of the metal ions [(1) M = Zn; (2) M = Mn]. As a result, both complexes are structurally similar to each other. The typical crystal structure of complex 1 is depicted in Fig. 2. Clearly, each Zn2+ ion in complex 1 is six-coordinated, equatorially by four dtcp ligands and axially by two SCN ions. Each ligand is bound to the metal atom in exo N atom, whereas the SCN ion acts as an N-bound monodentate ligand, which is almost linear. The Zn–N ˚ . The bond lengths are within the range of 2.13–2.18 A 2+ Zn ion sits on the crystallographic inversion center and the coordination geometry around the metal atom is a slightly distorted octahedron. As depicted in Fig. 3, each dtcp ligand in complex 1 connects two zinc atoms to build up a M4L4 metallocyclic ring in trans conformation, which differs from the cis mode for dtmp [11]. Two triazole units in each ligand with regard to the central phenyl ring make dihedral angles of 74.7o and 58.3o, respectively. In such a M4L4 metallocycle, those 1,3-alternate phenyl rings are parallel to each other, whereas 1,2-alternate ones make a dihedral angle of 56.5o. The polymeric structure of 1 consists of 2D flat
˚ ) and bond angles (°): Complex Fig. 2. Crystal structure of complex 1 drawn at 50% probability with the atom-numbering scheme. Selected bond length (A 1 Zn1–N1 2.1821(19), Zn1–N7 2.133(2), Zn1–N4 2.155(2), N1–Zn1–N7 91.50(8), N1–Zn1–N4 91.53(7), N1–Zn1–N7A 88.50(8), N4–Zn1–N7 90.82(8), N1–Zn1–N4A 88.47(7), S1–C13–N7 179.6(2); Complex 2: Mn1–N1 2.275(3), Mn1–N7 2.184(3), N1–Mn1–N7 92.15(10), N1–Mn1–N4A 87.93(9), N1– Mn1–N7C 87.85(10), N1–Mn1–N4D 92.07(9), S1–C13–N7 179.3(3).
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˚ ; complex 2: dO–N = 2.882(3) A ˚ ]. (For interpretation of Fig. 3. 2D polymeric structure of complex 1 [O–H N(dashed line): complex 1: dO–N = 2.888(3) A the references in colour in this figure legend, the reader is referred to the web version of this article.)
rhombus-type grid networks with each grid side having a ˚ . Similarly, each ligand in complex 2 links length of 13.47 A two Mn2+ ions in the trans conformation to form a M4L4 metallocyclic ring, which is further assembled into a 2D rhombus-type grid network via Mn–N coordination bonds ˚ long. Unlike the situations in and each grid side is 13.59 A dpmp and dtmp [10,11], it is worthy to note that the phenol group of dtcp ligand in these complexes is involved in the intramolecular hydrogen bond O–H N in the resulted 2D flat layer. In complexes 1 and 2, the 2D layers are organized parallel to the crystallographic a b plane with the interplanar ˚ and 5.01 A ˚ , respectively. The space distance of 4.99 A between the neighboring layers is occupied by the coordinated SCN groups. Especially, adjacent layers are arranged in an offset manner to place the metal atoms of one layer right above the centers of rhombus-type grids of the other (Fig. 4), which is comparable with the example of double
layers in Cu(II) complexes with 1,3-bis(1,2,4-triazol-1yl)propane [8]. Additionally, these 2D layers interplay weakly each other via various noncovalent interactions. For complex 1, the adjoining layers are associated together by hydrogen bond interactions (a), C1–H1 N3. In contrast, the separated layers A1–A2 (B1–B2) interact mutually via hydrogen bonds (b), C–H S, which exactly interpenetrate the void of rhombus-type grids in the intermediate layer B1 (A2). Strikingly, layers (A1–B2) with a double interplanar separation are further stabilized by remarkable Cl Cl contacts (c), which also pass through the grid cavities of the two middle layers (B1 and A2). Likewise, such noncovalent interactions as those in complex 1 are found as well in complex 2. Directional interactions between halogens, which are due to specific attractive forces [16], have been known for their wide application in systematic crystal engineering [17]. For the azole-containing organic ligand, a 1D pseudo polyrotaxane promoted A1
d M-M
a B1
a b
c
A2
dM-M
a
b
B2
M = Zn, Mn A B ˚ , symmetry code: x, 1/2 y, 1/ Fig. 4. Schematic showing noncovalent interactions between 2D flat layers. Complex 1 a: C1–H1 N3: dC1–N3 = 3.333(3) A ˚ , symmetry code: x, y, 1 + z; C12–H12 S1: dC12–S1 = 3.721(2) A ˚ , symmetry code: x, y, 1+z. c: Cl Cl 2 + z. b: C6–H6A S1: dC6–S1 = 3.739(2) A ˚ ). Complex 2 (a): C2–H2 N2: dC2–N2 = 3.370(4) A ˚ , symmetry code: x, 1/2 y, 1/2 + z; (b) C10–H10B S1: dC10– contacts (dashed lines, dCl Cl = 3.37 A ˚ ˚ S1 = 3.752(4) A, symmetry code: 1 + x, 1/2 y, 1/2 + z; (c) Cl Cl contacts (dCl Cl = 3.49 A).
H.-B. Zhu et al. / Inorganic Chemistry Communications 10 (2007) 362–366
by Br Br interactions was reported in complex [Zn2(bib)2(OAc)4] Æ 2H2O. Conversely, the bromo-group in [Zn(bib)2(H2O)2](NO3)2 Æ 2H2O and [Mn(bib)2(H2O)2](NO3)2 Æ 2H2O was involved neither in the hydrogen bonding nor in Br Br contacts [12]. To the best of our knowledge, it is the first example of MOFs with azole-containing ligands built from 2D flat layers via Cl Cl contacts. The thermal behaviors of complexes 1–2 were measured by using a TGA method under a nitrogen stream. The measurements show that complexes 1 and 2 remain stable up to 191 and 136 °C, respectively. Beyond these temperatures, the organic ligands dtcp are lost, and the complexes are decomposed. The residues at 700 °C for complexes 1 and 2 are 41.4% and 46.1%, respectively. The photoluminescence properties of complexes 1 and 2 were investigated in the solid state at ambient temperature. The measurements were carried out under the same conditions. Complex 1 exhibits luminescence with emission maximum at 468 ± 2 nm upon excitation at 397 nm, which is similar to ligand dtcp (emission maximum at 466 nm upon excitation at 397 nm). The emissions observed in complex 1 is probably from the p–p* intraligand fluorescence because of their close resemblance of the emission bands [6a]. However, no clear photoluminescence was observed for complex 2, which is possibly quenched by Mn(II) ions. In summary, we have obtained novel metal-organic frameworks constructed by 2D flat layers mediated by Cl Cl contacts and hydrogen bonds, which is primarily ascribed to the presence of chloro-group in the dtcp ligand and SCN coordinating ions. Supplementary material CCDC 625277 and 625278 contain the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/ conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected]. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2006.11.015.
[2]
[3]
[4]
[5]
[6]
[7]
[8] [9]
[10] [11] [12]
Acknowledgement [13]
The authors are grateful to the financial support by the National Natural Science Foundation of China (Projects 20271026 and 20301009). Thanks are also due to Postdoctoral Research Fund from Jiangsu Province Personnel Department (0502005B) and Postdoctoral Research Fund of China (20060390278) to Dr. Zhu. References [1] (a) W. Huang, H.B. Zhu, S.H. Gou, Coord. Chem. Rev. 250 (2006) 414;
[14]
365
(b) L. Carlucci, G. Ciani, D.M. Proserpio, Coord. Chem. Rev. 246 (2003) 247; (c) M. Eddaoudi, D.B. Moler, H.L. Li, B.L. Chen, T.M. Reineke, M. O’ Keefe, Q.M. Yaghi, Acc. Chem. Res. 34 (2001) 319; (d) S.R. Batten, Curr. Opin. Solid State Mater. Sci. 5 (2001) 107; (e) P.J. Stang, B. Olenyuk, Acc. Chem. Res. 32 (1999) 975. (a) S. Kitagawa, R. Kitaura, S.L. Noro, Angew. Chem. Int. Ed. 43 (2004) 2334; (b) C. Janiak, Dalton Trans. (2003) 2781; (c) M.J. Zaworotko, Chem. Commun. (2001) 1; (d) B.F. Hoskins, R. Robson, D.A. Slizys, J. Am. Chem. Soc. 119 (1997) 2952. (a) L. Carlucci, G. Ciani, P. Macchi, D.M. Proserpio, S. Rizaato, Chem. Eur. J. 5 (1999) 237; (b) J.S. Fleming, K.L.V. Mann, C.A. Carraz, E. Psillakis, J.C. Jeffry, J.A. McCleverty, M.D. Ward, Angew. Chem. Int. Ed. 37 (1998) 1279. (a) M. Du, X.J. Zhao, S.R. Batten, J. Ribas, Cryst. Growth Des. 5 (2005) 901; (b) S.L. Li, J.H. Shao, Y.Z. Zhao, Y.X. Wang, Chin. J. Inorg. Chem. 19 (2003) 1059; (c) Y. Diskin-Posner, G.K. Patra, I. Goldberg, Chem. Commun. (2002) 1420; (d) A.C. Benyei, P.I. Coupar, G. Ferguson, C. Glidewell, A.J. Lough, P.R. Meehan, Acta Crystallogr. Sect. C 54 (1998) 1515. (a) Y.F. Peng, H.Y. Ge, B.Z. Li, B.L. Li, Y. Zhang, Cryst. Growth Des. 6 (2006) 994; (b) B.L. Li, X. Zhu, J.H. Zhou, Y.F. Peng, Y. Zhang, Polyhedron 23 (2004) 3133; (c) J.H. Zhou, Y.F. Peng, Y.P. Zhang, B.L. Li, Y. Zhang, Inorg. Chem. Commun. 7 (2004) 1181; (d) B.L. Li, Y.F. Peng, B.Z. Li, Y. Zhang, Chem. Commun. (2005) 2333. (a) H.F. Zhu, J. Fan, T.A. Okamura, W.Y. Sun, N. Ueyama, Cryst. Growth Des. 5 (2005) 289; (b) B.L. Fei, W.Y. Sun, Y.A. Zhang, K.B. Yu, W.X. Tang, J. Chem. Soc. Dalton Trans. (2000) 2345; (c) B. Sui, J. Fan, T.A. Okamura, W.Y. Sun, N. Ueyama, New. J. Chem. 25 (2001) 1379. (a) Y. Garcia, G. Bravic, C. Gieck, D. Chasseau, W. Tremel, P. Gutlich, Inorg. Chem. 44 (2005) 9723; (b) Y. Garcia, O. Kahn, L. Rabardel, ; B. Chansou, L. Salmon, J.P. Tuchagues, Inorg. Chem. 38 (1999) 4663. G.A. Albada, R.C. Guijt, J.G. Haasnoot, M. Lutz, A.L. Spek, J. Reedijk, Eur. J. Inorg. Chem. (2000) 121. (a) B.F. Hoskins, R. Robson, D.A. Slizys, ; J. Am. Chem. Soc. 119 (1997) 2952; (b) B.F. Hoskins, R. Robson, D.A. Slizys, Angew. Chem. Int. Ed. 36 (1997) 2336. C.T. Chen, W.K. Chang, S.C. Sheu, G.H. Lee, T.I. Ho, Y.C. Lin, Y. Wang, J. Chem. Soc. Dalton Trans. (1991) 1569. H.B. Zhu, C.H. Huang, W. Huang, S.H. Gou, Inorg. Chem. Commun. 7 (2004) 1095. J. Fan, W.Y. Sun, T. Okamura, Y.Q. Zheng, B. Sui, Cryst. Growth Des. 4 (2004) 579. The ligand, dtcp, was prepared according to our formerly reported procedure [11]. Yield: 78%. IR mKBr (cm 1): 3280 m, 3132 m, 3109 m, 1509 m, 1481 m, 1133 m, 1107 m, 681 m, 653 m. 1H NMR (CDCl3 25 °C): d = 10.12 (br, 1H, OH), 8.20 (s, 2H, triazole-H), 7.95 (s, 2H, triazole-H), 7.26 (s, 2H, phenyl-H), 5.31 (s, 4H, –CH2–). Anal. Calc. for C12H11ClN6O: C, 49.58; H, 3.81; N, 28.91. Found: C, 49.51; H, 3.65; N, 28.72. [Zn(dtcp)2](SCN)2 (1). A solution of dtcp (0.2 mmol), Zn(NO3)2 (0.1 mmol) and NH4SCN (0.25 mmol) in 20 ml MeOH was refluxed for 2 h and cooled to room temperature. After filtration, the mother liquid remained at room temperature for three days to give crystals suitable for X-ray analysis. Yield: 72%. IR mKBr (cm 1): 3291 m, 3121 m, 2069 s, 1521 m, 1468 m, 1132 m, 677 m, 6445 m. 1H NMR (DMSO-d6 25°C): d = 9.76 (s, 1H, OH), 8.59 (s, 2H, triazole-H), 7.99
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(s, 2H, triazole-H), 7.04 (s, 2H, phenyl-H), 5.41 (s, 4H, –CH2–). Anal. Calc. for C26H22Cl2ZnN14O2S2: C, 40.93; H, 2.91; N, 25.70. Found: C, 40.80; H, 2.75; N, 25.52. [Mn(dtcp)2](SCN)2 (2). The complex was prepared in a similar procedure to that for complex 1. Yield: 75%. IR mKBr (cm 1): 3278 m, 3110 m, 2057 s, 1520 m, 1483 m, 1133 m, 676 m, 645 m. Anal. Calc. for C26H22Cl2MnN14O2S2: C, 41.50; H, 2.95; N, 26.06. Found: C, 41.54; H, 2.55; N, 25.22. [15] Diffraction intensities for complexes 1 and 2 were collected at 293(2) K on a Bruker SMART CCD-4K diffractometer employing graphite˚ ). The data were monochromated MoKa radiation (k = 0.71073 A collected using SMART and reduced by the program SAINT. All the structures were solved by direct methods and refined by full-matrix least squares method on F 2obs by using SHELXTL-PC software package. Non-hydrogen atoms were placed in geometrically calculated positions. Crystal data for 1: C26H22Cl2ZnN14O2S2, M = 763.01, monoclinic, space group P21/c, a = 11.5288(11), b = 13.316(1), c =
˚ , b = 100.783(1)°, V = 1556.2(3) A ˚ 3, D = 1.628 g cm 3, 10.319(1) A Z = 2, F (0 0 0) = 776. Unique data (Rint) = 2723 (0.060), GOF = 1.04, R1 = 0.0326, wR2 = 0.0889. 2: C26H22Cl2MnN14O2S2, M = 752.56, monoclinic, space group P21/c, a = 11.560(2), ˚ , b = 100.130(3)°, V = 1590.9(5) A ˚ 3, b = 13.428(2), c = 10.411(2) A 3 D = 1.571 g cm , Z = 2, F (0 0 0) = 766. Unique data (Rint) = 2789(0.040), GOF = 1.02, R1 = 0.0481, wR2 = 0.1180. [16] G.R. Desiraju, R. Parthasarathy, J. Am. Chem. Soc. 111 (1989) 8725. [17] (a) A. Matsumoto, T. Tanaka, T. Tsubouchi, K. Tashiro, S. Saragai, S. Nakamoto, J. Am. Chem. Soc. 124 (2002) 8891; (b) J.N. Moorthy, R. Natarajan, P. Mal, P. Venugopalan, J. Am. Chem. Soc. 124 (2002) 6530; (c) K. Tanaka, D. Fujimoto, A. Altreuther, T. Oeser, H. Irngartinger, F. Tode, J. Chem. Soc. Perkin Trans. 2 (2000) 2115; (d) D.S. Reddy, D.C. Craig, G.R. Desiraju, J. Am. Chem. Soc. 118 (1996) 4090.