Synthesis, Crystal Structure, and Magnetic Properties of a Coordination Polymer [{KMn4(IDC)3(prz)}· 3H2O]n with 1D Channels.
A 3D coordination polymer with 1D hexagonal channels of [KMn4(IDC)3(prz)· 3H2O]n (1) (H3IDC = imidazole-4,5-dicarboxylic acid, prz = piperazine) was hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic with four independent Mn(II) atoms. The IDC3 − anions alternately bridge the Mn(2) and Mn(4) cations to form a 1D infinite linear chain, which is connected by the Mn(1) and Mn(3) through IDC3 − ligands to generate a concertina sheet. The sheets are further interlinked by IDC3 − ligands to form 3D frameworks with 1D hexagonal channels (7.251 × 8.677 Å), which is occupied by water molecules and K+ ions. Magnetic susceptibility measurements of 1 exhibit antiferromagnetic interactions between the nearest Mn(II) atoms.
Keywords: imidazole-4,5-dicarboxylic acid; porous; channel; magnetism
INTRODUCTION
In recent years, much attention has focused on the design and synthesis of nanoporous metal-organic hybrid materials with channels or cavities, owing to their potential applications in ion exchange,[[1]] gas separation,[[2]] catalysis,[[3]] and magnetic[[4]] aspects. However, the synthesis of such functional porous networks is often unsuccessful, because of the formation of an interpenetrating structure, which provides only small-sized channels or none at all.[[5]] In order to solve it, two methods were used, the first, using metal clusters as motifs and the second using plane ligands with multi-coordinated sites.
The combination of metal ions and bridging ligands containing different dicarboxylates or rigid and flexible pillars (pyridyl containing) or both can allow the formation of coordination networks possessing permanent porosity and high thermal stability. Many multi-carboxylate or heterocylic carboxylic acids are used for formation of coordination networks possessing permanent porosity and high thermal stability, because of the diversity of the binding modes with metal atoms.[[6]]
In addition to transition metal ions, alkali cations are intriguing because of their various coordination modes, low polarizability, and unique affinity for basic molecules ranging from a strong base, NH3, to a weak one, acetone. For instance, alkali cations in zeolites are well known to be catalytic sites for hydrocarbon transformation and also serve as guest recognition sites in biological systems.[[7]]
From this viewpoint, we designed and synthesized a heterometallic PCP containing transition metal ions as connectors of a framework and alkali metal ions as affinity sites in the pores.
Herein, we report the synthesis, crystal structure, and magnetic properties of one 3D open framework with imidazole-4,5dicarboxylic acid (H3IDC) and piperzine: [{KMn4(IDC)3(prz)}· 3H2O]n (1) (H3IDC = imidazole-4,5-dicarboxylic acid, prz = piperazine). Magnetic susceptibility measurements of 1 exhibit antiferromagnetic interactions between the Mn(II) ions.
EXPERIMENTAL
Materials
All chemicals and solvents were of A.R. grade and used without further purification. Carbon, hydrogen, and nitrogen were determined using an Elementar Vario EL elemental analyzer (Elementar, Germany). IR spectra were recorded using KBr pellets and a Bruker EQUINOX 55 spectrometer (SHIMADZU, Japan). Thermogravimetric analysis (TG) data were collected on a Netzsch TG-209 instrument (NETZSCH, Germany) with a heating rate of 10°C/min. The variation temperature X-ray powder diffraction (XRPD) measurements were recorded on a RIGAKU D/MAX 2200 VPC diffractometer (RIGAKU, Japan). Magnetic susceptibility data were collected in the 2–300 K temperature range with a Quantum Design SQUID Magnetometer MPMS XL-7 (Quantum Design, USA) and a field of 0.1 T. A correction was made for the diamagnetic contribution prior to data analysis.
Synthesis of Compound 1
[KMn 4 (IDC) 3 (prz)· 3H 2 O] n (1)
A mixture of MnSO4· 2H2O (0.281 g, 1.5 mmol), H3IDC (0.156 g, 1.0 mmol), KOH (0.196 g, 3.5 mmol), prz (0.098 g, 0.5 mmol), and H2O (7 mL) was sealed in a 25-mL Teflon-lined stainless steel vessel and heated at 180°C for 2 days, followed by cooling to room temperature at a rate of 10°C/h. Pale yellow rhombohedral crystals of 1 were isolated and washed with distilled water (yield 0.225 g, 70%). Elemental Anal. Calcd. for C19H19N8O15Mn4K (1· 3H2O) (F.W.): C 26.59 (26.65), H 2.23 (2.46), N 13.06 (12.80)%. IR (KBr, cm− 1): νOH 3400, νNH 3224, νas(CO2) 1573 and 1519, νs(CO2) 1471 and 1381.
Crystal Structure Determination
Single-crystal data for 1 were collected at 273(2) K on a Bruker Smart 1000 CCD diffractometer (Bruker, Germany) with Mo Kα radiation (λ = 0.71073 Å). All empirical absorption corrections were applied using the SADABS program.[[8]] The structure was solved using direct method, which yielded the positions of all nonhydrogen atoms. These were refined first isotropically and then anisotropically. All the hydrogen atoms (except the ones bound to water molecules) were placed in calculated positions with fixed isotropic thermal parameters and included in structure factor calculations in the final stage of full-matrix least-squares refinement. The hydrogen atoms of coordinated water molecules in 1 were located in the difference Fourier map and refined isotropically. All calculations were performed using the SHELXTL-97 system of computer programs.[[9]] The crystallographic data are summarized in Table 1. The selected bond lengths and angles are listed in Table 2.
TABLE 1 Crystal data for
| Formula | C19H19KMn4N8O15 |
| M (g mol− 1) | 858.28 |
| Crystal system | Monoclinic |
| Space group | Cc |
| a (Å) | 15.867(4) |
| b (Å) | 12.834(3) |
| c (Å) | 14.794(3) |
| α (°) | 90.0 |
| β (°) | 116.818(5) |
| γ (°) | 90.0 |
| V (Å3) | 2688.4(11) |
| Z | 4 |
| Dcalc | 2.120 |
| Crystal size (mm3) | 0.42 × 0.21 × 0.18 |
| F(000) | 1712 |
| μ (Mo-Kα)/mm− 1 | 2.084 |
| θ (°) | 2.23 to 27.03 |
| Reflections collected | 4395 |
| Independent reflections(I ≥ 2σ (I)) | 3049 |
| Limiting indices | −20 ≤ h ≤ 19, −4 ≤ k ≤ 16, |
| −18 ≤ l ≤ 18 |
| Parameters | 404 |
| Absolute parameter | 0.01(2) |
| Δ (ρ) (e· Å− 3 −) | 0.818, −0.482 |
| Goodness-of-fit | 1.029 |
| R | 0.0412 (0.0820) |
| wR | 0.0612 (0.0899) |
| CCDC No. | 688710 |
| . |
TABLE 2 Selected bond distances (Å) and bond angles (°) for
| Mn(1)-O(1) | 2.234(5) | Mn(1)-O(10) | 2.106(5) | Mn(1)-O(11) | 2.184(4) |
| Mn(1)-N(2) | 2.199(6) | Mn(1)-N(3) | 2.188(6) | Mn(2)-O(8) | 2.215(5) |
| Mn(2)-O(9) | 2.241(5) | Mn(2)-O(12)#4 | 2.076(5) | Mn(2)-N(6) | 2.158(5) |
| Mn(2)-N(7) | 2.119(7) | Mn(3)-O(1)#2 | 2.222(4) | Mn(3)-O(4)#5 | 2.221(5) |
| Mn(3)-O(5) | 2.163(5) | Mn(3)-O(7) | 2.211(5) | Mn(3)-N(1)#6 | 2.267(6) |
| Mn(3)-N(4)#5 | 2.177(6) | Mn(4)-O(2) | 2.186(5) | Mn(4)-O(3) | 2.108(5) |
| Mn(4)-O(6) | 2.243(5) | Mn(4)-O(12)#7 | 2.263(5) | Mn(4)-N(5) | 2.170(6) |
| Mn(4)-N(8)#7 | 2.165(7) | O(10)-Mn(1)-O(11) | 87.84(19) | O(10)-Mn(1)-N(3) | 109.9(2) |
| O(11)-Mn(1)-N(3) | 90.32(19) | O(10)-Mn(1)-N(2) | 147.9(2) | O(11)-Mn(1)-N(2) | 94.1(2) |
| N(3)-Mn(1)-N(2) | 102.1(2) | O(10)-Mn(1)-O(1) | 92.98(19) | O(11)-Mn(1)-O(1) | 162.74(17) |
| N(3)-Mn(1)-O(1) | 73.18(19) | N(2)-Mn(1)-O(1) | 94.3(2) | O(12)#4-Mn(2)-N(7) | 129.8(2) |
| O(12)#4-Mn(2)-N(6) | 134.0(2) | N(7)-Mn(2)-N(6) | 95.9(2) | O(12)#4-Mn(2)-O(8) | 89.52(19) |
| N(7)-Mn(2)-O(8) | 113.0(2) | N(6)-Mn(2)-O(8) | 73.92(19) | O(12)#4-Mn(2)-O(9) | 99.34(19) |
| N(7)-Mn(2)-O(9) | 75.5(2) | N(6)-Mn(2)-O(9) | 86.5(2) | O(8)-Mn(2)-O(9) | 159.10(18) |
| O(5)-Mn(3)-N(4)#5 | 93.7(2) | O(5)-Mn(3)-O(7) | 84.41(19) | N(4)#5-Mn(3)-O(7) | 170.12(19) |
| O(5)-Mn(3)-O(4)#5 | 96.35(19) | N(4)#5-Mn(3)-O(4)#5 | 74.61(19) | O(7)-Mn(3)-O(4)#5 | 95.93(17) |
| O(5)-Mn(3)-O(1)#2 | 84.26(18) | N(4)#5-Mn(3)-O(1)#2 | 107.92(19) | O(7)-Mn(3)-O(1)#2 | 81.58(17) |
| O(4)#5-Mn(3)-O(1)#2 | 177.37(18) | O(5)-Mn(3)-N(1)#6 | 165.16(19) | N(4)#5-Mn(3)-N(1)#6 | 99.6(2) |
| O(7)-Mn(3)-N(1)#6 | 83.6(2) | O(4)#5-Mn(3)-N(1)#6 | 93.6(2) | O(1)#2-Mn(3)-N(1)#6 | 85.3(2) |
| O(3)-Mn(4)-N(8)#7 | 158.04(19) | O(3)-Mn(4)-N(5) | 111.2(2) | N(8)#7-Mn(4)-N(5) | 89.1(2) |
| O(3)-Mn(4)-O(2) | 87.4(2) | N(8)#7-Mn(4)-O(2) | 100.7(2) | N(5)-Mn(4)-O(2) | 91.3(2) |
| O(3)-Mn(4)-O(6) | 87.42(19) | N(8)#7-Mn(4)-O(6) | 90.6(2) | N(5)-Mn(4)-O(6) | 73.95(19) |
| O(2)-Mn(4)-O(6) | 161.33(18) | O(3)-Mn(4)-O(12)#7 | 86.88(18) | N(8)#7-Mn(4)-O(12)#7 | 73.0(2) |
| N(5)-Mn(4)-O(12)#7 | 161.9(2) | O(2)-Mn(4)-O(12)#7 | 89.53(18) | O(6)-Mn(4)-O(12)#7 | 108.08(17) |
| Symmetry transformations used to generate equivalent atoms: #2: x + 1/2, y + 1/2, z; #4: x + 1/2, −y + 1/2, z + 1/2; #5: x + 1/2, −y + 3/2, z + 1/2; #6: x + 1, −y + 1, z + 1/2; #7: x, −y + 1, z + 1/2. |
RESULTS AND DISCUSSION
Synthesis and Characterization of Compound 1
Compound 1 was obtained by hydrothermal reactions of MnSO4· 2H2O, H3IDC, KOH, prz, and H2O in a molar ratio of 3:2:7:1:1100 with medium yields. The pH values of the solution before and after reaction are ca. 9 and 8, respectively. Slightly excessive or less KOH wound cause failure. The reaction route as follows:
Graph
Crystal Structure of Compound 1
X-ray crystallography reveals that compound 1 crystallizes in monoclinic with four independent Mn(II) atoms. As shown in Fig. 1, both Mn(1) and Mn(2) atoms are five-coordinated to form less common square pyramidal geometry,[[10]] Mn(1)N2O3 and Mn(2)N2O3. In the Mn(1)N2O3 moiety the five donors are one N atom of the prz, one N atom of an imidazole ring, and three O atoms of two individual IDC3 −. The Mn(1)–O and Mn(1)–N distances are 2.106(5)–2.234(5) and 2.188(6)–2.199(6) Å, respectively. In the Mn(2)N2O3 moiety the five donors are from three individual IDC3 −. The Mn(2)–O and Mn(2)–N distances are 2.076(5)–2.241(5) and 2.119(7)–2.158(5) Å, respectively. However, both Mn(3) and Mn(4) atoms are six-coordinated to form octahedral Mn(3)N2O4 and Mn(4)N2O4. In the Mn(3)N2O4 moiety the six donors are one N atom of the prz, one N atom of an imidazole ring, and four O atoms of three individual IDC3 −. The Mn(3)–O and Mn(3)–N distances are 2.163(5)–2.222(4) and 2.177(6)–2.267(6) Å, respectively. In the Mn(4)N2O4 moiety the six donors are from three individual IDC3 −. The Mn(4)–O and Mn(4)–N distances are 2.108(5)–2.263(5) and 2.165(7)–2.170(6) Å, respectively. IDC3 − anions take three coordination fashion: μ4-IDC3 −, μ5-IDC3 −, and μ6-IDC3 − (Scheme 1). Piperazine takes bridging fashion (Mn(1) and Mn(3)).
Graph: FIG. 1 The coordination environments of Mn2 +, μ4-IDC3 −, μ5-IDC3 −,μ6-IDC3 −, K+, and prz in 1. Hydrogen atoms and water molecules are omitted for clarity (symmetry code: (ii) x + 1/2, y + 1/2, z; (iii) x − 1/2, y − 1/2, z; (viii) x − 1, −y + 1, z − 1/2; (viiii) x − 1/2, −y + 3/2, z − 1/2; (vv) x, −y + 1, z − 1/2; (vvii) x − 1/2, −y + 1/2, z − 1/2).
Graph: SCH. 1 The coordination fashion of IDC3 − anions in compound 1.
The IDC3 − anions alternately bridge the Mn(2) and Mn(4) cations to form a 1D infinite linear chain (Fig. 2), which is connected by the Mn(1) and Mn(3) through IDC3 − ligands to generate a concertina sheet (Fig. 3). These sheets are further interlinked by IDC3 − ligands to form 3D frameworks with 1D hexagonal channels (7.251 × 8.677 Å) along the c axis (Fig. 4), which is occupied by water molecules and K+ ions.
Graph: FIG. 2 The IDC3 − anions alternately bridge the Mn(2) and Mn(4) cations to form a 1D infinite linear chain. Hydrogen atoms, K+ ions, and water molecules are omitted for clarity.
Graph: FIG. 3 1D infinite linear chains are connected by the Mn(1) and Mn(3) through IDC3 − ligands to generate a concertina sheet. Hydrogen atoms, K+ ions, and water molecules are omitted for clarity.
Graph: FIG. 4 View of the three-dimensional metal-organic framework of 1 along the b axis. Water molecules and hydrogen atoms have been omitted for clarity.
X-ray Powder Diffraction and Thermal Analysis
In order to examine the thermal stability of the porous networks, thermal gravimetric (TG) analyses and measurements of the XRPD patterns were carried out. The XRPD patterns in Fig. 5 show that the frameworks of 1 are stable below 400°C, which is according with the results of the TG analyses (Fig. 6).
Graph: FIG. 5 The XRPD patterns of 1 at different temperatures; the simulated patterns are generated from single-crystal diffraction data.
Graph: FIG. 6 The TGA curve for compound 1.
Magnetic Properties
The temperature-dependent magnetic properties of 1 are shown in Fig. 7 in the forms of χMT and 1/χM vs. T curves. The χMT value at room temperature, 17.2 cm3 mol− 1 K (11.7 μB), is close to the value of 17.5 cm3 mol− 1 K (11.8 μB) expected for magnetically four isolated high-spin Mn(II) (SMn = 5/2, g = 2.0). Upon cooling, the value of χMT decreases monotonically, attaining a value of 1.27 cm3 mol− 1 K at 2 K. Between 2 and 300 K, the magnetic susceptibilities can be fitted to the Curie-Weiss law,χM = CM/(T − Θ), with CM = 18.5 cm3 mol− 1, Θ = −22.6 K. These results indicate weak antiferromagnetic interactions between the neighboring Mn(II) ions.
Graph: FIG. 7 Temperature dependence of χ MT (O) and 1/χ M(ϒ)vs. T for 1. The black line shows the Curie-Weiss fitting.
SUPPLEMENTARY MATERIAL
Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Center, CCDC No. 688710. A copy of this information may be obtained free of charge from the Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-336-033; email: deposit@ccdc.cam.ac.uk; or http://www.ccdc.cam.ac.uk).
Acknowledgments
This work was supported by the National Science Fund for Distinguished Young Scholars of China (20625103), NSFC (20371051).
[
REFERENCES
1
Manos, M.J., Iyer, R.G., Quarez, E., Liao, J.H. and Kanatzidis, M.G.2005. Sn[Zn4Sn4S17]6 −: a robust open framework based on metal-linked penta-supertetrahedral [Zn4Sn4S17]10 − clusters with ion-exchange properties. Angew. Chem. Int. Ed., 44: 3552–3555.
2
Rowsell, J.L. C. and Yaghi, O.M.2006. Effects of functionalization, catenation, and variation of the metal oxide and organic linking units on the low-pressure hydrogen adsorption properties of metal-organic frameworks. J. Am. Chem. Soc., 128: 1304–1315.
3
Zou, R.Q., Sakurai, H. and Xu, Q.2006. Preparation, adsorption properties, and catalytic activity of 3D porous metal-organic frameworks composed of cubic building blocks and alkali-metal ions. Angew. Chem. Int. Ed., 45: 2542–2546.
4
Zhu, Y., Zhang, L., Schappacher, F.M., Pöttgen, R., Shi, J. and Kaskel, S.2008. Synthesis of magnetically separable porous carbon microspheres and their adsorption properties of phenol and nitrobenzene from aqueous solution. J. Phys. Chem. C, 112: 8623–8628.
5
Yaghi, O.M., Davis, C.E., Li, G. and Li, H.1997. Selective guest binding by tailored channels in a 3-D porous zinc(II)-benzenetricarboxylate network. J. Am. Chem. Soc., 119: 2861–2868.
6
Lu, W.G., Su, C.Y., Lu, T.B., Jiang, L. and Chen, J.M.2006. Two stable 3D metal-organic frameworks constructed by nanoscale cages via sharing the single-layer walls. J. Am. Chem. Soc., 128: 34–35.
7
Horike, S., Matsuda, R., Tanaka, D., Mizuno, M., Endo, K. and Kitagawa, S.2006. Immobilization of sodium ions on the pore surface of a porous coordination polymer. J. Am. Chem. Soc., 128: 4222–4223.
8
Sheldrick, G.M.1997. SADABS. Program for Empirical Absorption Correction of Area Detector Data, Germany: University of Göttingen.
9
Sheldrick, G.M.1997. SHELXL-97. Program for Crystal Structure Solution and Refinement, Germany: University of Göttingen.
Matsuda, R., Kitaura, R., Kitagawa, S., Kubota, Y., Kobayashi, T.C., Horike, S. and Takata, M.2004. Guest shape-responsive fitting of porous coordination polymer with shrinkable framework. J. Am. Chem. Soc., 126: 14063–14070.
]
[
Footnotes
a
R = Σ < eqid1 > |Fo| −|Fc < eqid2 > |/Σ |Fo|, wR2 = [Σ [w(Fo2− Fc2)2]/Σ w(Fo2)2]1/2; [Fo > 4α(Fo)]
b
Based on all data.
]
By Jin-Zhong Gu; Zhu-Qing Gao; Wei Dou; Wen-Guan Lu and Tong-Bu Lu
Reported by Author; Author; Author; Author; Author
