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Synthesis, structure, and adsorption properties of a three-dimensional porous yttrium–organic coordination network
Microporous and Mesoporous Materials 98 (2007) 16–20 www.elsevier.com/locate/micromeso
Synthesis, structure, and adsorption properties of a three-dimensional porous yttrium–organic coordination network Jinxi Chen, Zhenxia Chen, Ting Yu, Linhong Weng, Bo Tu, Dongyuan Zhao
*
Molecular Catalysis and Innovative Materials Laboratory, Department of Chemistry, Advanced Materials Laboratory, Fudan University, Shanghai 200433, PR China Received 18 May 2006; received in revised form 11 August 2006; accepted 17 August 2006 Available online 26 September 2006
Abstract Deprotonation of 4,4 0 -biphenyldicarboxylic acid (H2BPDC) with triethylamine followed by the copolymerization with Y(III) in N,Ndimethylformamide (DMF) at room temperature yields a new three-dimensional (3-D) porous metal–organic coordination network, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1). Compound 1 (C24.50H19N1.50O9Y) crystallizes in the triclinic P-1 space group ˚ , a = 111.058 (5), b = 90.187 (5), c = 94.318 (5), V = 1520.9 (7) A ˚ 3, and Z = 2). X(a = 8.220 (2), b = 13.998 (4), c = 14.212 (4) A ˚ along ray crystallography reveals that 1 consists of a 3-D framework contained open 1-D channels with the dimension of 5 · 10 A the crystallographic a axis. The adsorption measurements show that compound 1 can adsorb N2, Ar and CO2 into its pores. The adsorption isotherms for MeOH and H2O were also measured. 2006 Elsevier Inc. All rights reserved. Keywords: Metal–organic coordination networks; Yttrium; Carboxylate ligands; Adsorption
1. Introduction The construction of porous metal–organic coordination networks (MOCNs) through crystal engineering has attracted much interest because of their unusual topologies and potential applications in gas adsorption [1–3], size and shape selective separation [4,5], and heterogeneous catalysis [6–8]. This class of materials can be easily obtained through self-assembly of a potentially multifunctional ligand with a metal ion that has more than one vacant or labile site. In principle, through the wide choice of metals, and the infinite choice and design of ligands, a broad range of magnetic, electrical, optical, and catalytic properties might be rationally incorporated into such materials. Seeing about a rich variety of MOCNs, transition metal elements are usually preferred over rare earth elements for the construction of MOCNs since the rare earth metals have
*
Corresponding author. Tel.: +86 21 65642036; fax: +86 21 65641740. E-mail address: [email protected] (D. Zhao).
1387-1811/$ - see front matter 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2006.08.015
high and variable coordination numbers and flexible coordination geometries. While this flexibility would make obstacles to the design of MOCNs, and also lead to exotic molecular architectures. Recently, a few lanthanide carboxylate coordination networks which endow unique magnetic and fluorescence properties have been reported [9–11]. However, until now, the yttrium–organic coordination networks are rare although yttrium is widely used in fluorescence, laser crystals, and superconductive materials [12]. In this work, we used 4,4 0 -biphenyldicarboxylic acid (H2BPDC), an extended analogue of 1,4-benzenedicarboxylic acid (H2BDC), and Y(III), one of the smallest rare earth ions to construct a new 3-D open MOCN under ambient condition. The interest of yttrium lies in facile construction of its unusual clusters [13]. Combining the larger size of BPDC as compared to that of BDC with abundant yttrium clusters may result in coordination networks with large cavity dimensions. The 3-D porous MOCN, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1) reported herein possesses 1-D open pore channels with the size of ˚ along the crystallographic a axis. It shows a 5 · 10 A
J. Chen et al. / Microporous and Mesoporous Materials 98 (2007) 16–20
microporosity with the adsorption of N2, Ar, CO2, H2O, and methanol.
17
Table 1 Crystal data and structure refinement for compound 1 1
2. Experiment section 2.1. Preparation of [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1) The compound 1 was prepared by liquid–liquid diffusion at room temperature. In a typical reaction, 4,4 0 -biphenyldicarboxylic acid (H2BPDC; 0.049 g, 0.2 mmol) (Aldrich) and Y(NO3)3 Æ 6H2O (0.084 g, 0.2 mmol) was dissolved in DMF (15 ml). Then a solution of triethylamine (0.2 ml) and DMF (2 ml) was allowed to diffuse slowly into the above mixture. After 2 weeks, colourless transparent crystals were obtained. Yield: 81%. C24.50H19N1.50O9Y (M = 567.32); C 51.26 (Calcd. 51.57); H 3.43 (3.86); N 3.68 (3.92)%. FT-IR (KBr pellet, cm1) 3355s, 3130s, 2454br, 1911br, 1665s, 1582s, 1520s, 1414s, 1241s, 1082m, 954s, 831s, 775s, 753s, 621w, 534m, 423w, 407m. 2.2. Characterization The CHN elemental microanalysis data were obtained using a Vario EL elemental analyzer. Infrared (IR) sample was prepared as KBr pellets, and spectra were obtained in the 4000–400 cm1 range using a Nicolet Avatar 360 FTIR spectrometer. X-ray powder diffraction (XRPD) data were collected on a Bruker D8 diffractometer with Cu Ka ˚ ). A Perkin–Elmer TGA7 thermoradiation (k = 1.5418 A gravimetric analyzer was used to obtain TGA curve in air with a heating rate of 5 C/min. The adsorption isotherms of nitrogen at 77 K, argon at 77 K, carbon dioxide at 195 K, and H2O and MeOH at room temperature were measured with BELSORP18 volumetric adsorption equipment from Bel Japan, Inc. 2.3. X-ray crystallographic measurements Single crystal (0.2 · 0.3 · 0.3 mm3) X-ray diffraction data were recorded on a Bruker SMART-APEX diffractometer equipped with a CCD detector with Mo Ka ˚ ). The raw data frames were interadiation (k = 0.71073 A grated into SHELX-format reflection files and corrected for Lorentz and polarization effects using the SAINT program and for absorption using the SADABS program [14]. Structure solution and full-matrix least-squares refinement based on F2 were performed with the SHELXS-97 and SHELXL-97 program packages [15], respectively. All non-hydrogen atoms except those from guest molecules were refined anisotropically and hydrogen P atoms were located and refined isotropically. Final R = kFojFck/ P P 2 P 2 1=2 wðF 2o Þ , with jFoj, and wRðF 2 Þ ¼ ½ wðF 2o F 2c Þ = 2 2 2 w ¼ 1=½r ðF o Þ þ ðaP Þ þ bP [where P ¼ ðMaxðF 2o ; 0Þþ 2F 2c Þ=3Þ. Details on crystal data and intensity data were given in Table 1. The selected bond distances and bond
Empirical formula Formula weight Crystal size Temperature Wavelength Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) U (A Z D (calcd) (Mg m3) l (mm1) F(0 0 0) h range for data collection Limiting indices
C24.5H19N1.5O9Y 567.32 0.2 · 0.3 · 0.3 mm 298(2) K 0.71073 A Triclinic P-1 8.220(2) 13.998(4) 14.212(4) 111.058(5) 90.187(5) 94.318(5) 1520.9(7) 2 1.239 1.961 575 2.83–27.16 10 6 h 6 10, 17 6 k 6 17, 9 6 l 6 18 7669/6464 [R(int) = 0.0577] 95.6%
Reflections collected/unique Completeness to theta = 25.01 Refinement method Full-matrix least-squares on F2 Data/restraints/parameters 6464/0/321 Goodness-of-fit on F2 0.954 Final R indices [I > 2r(I)] R1,a = 0.0743, wRb2 ¼ 0:1354 R indices (all data) R1,a = 0.1863, wRb2 ¼ 0:1542 ˚ 3 Largest diff. peak and hole 0.912 and 0.419 e · A P P P P a R = kFojFck/ jFoj. wRðF 2 Þ ¼ ½ wðF 2o F 2c Þ2 = wðF 2o Þ2 1=2 . 2 w ¼ 1=½r2 ðF 2o Þ þ ð0:0150P Þ þ 0:00P ], where P ¼ ðMaxðF 2o ; 0Þ þ 2F 2c Þ=3 for 1.
angles were shown in Table 2. CCDC-196816 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge at http:// www.ccdc.cam.ac.uk/conts/retrieving.html. Table 2 ˚ ) and angles () for compound 1 Selected bond lengths (A Y(1)–O(8) Y(1)–O(6)#1 Y(1)–O(2) Y(1)–O(7) Y(1)–O(6)#2 O(8)–Y(1)–O(6)#1 O(8)–Y(1)–O(2) O(6)#1–Y(1)–O(2) O(8)–Y(1)–O(7) O(6)#1–Y(1)–O(7) O(2)–Y(1)–O(7) O(8)–Y(1)–O(5)#2 O(6)#1–Y(1)–O(5)#2 O(2)–Y(1)–O(5)#2 O(7)–Y(1)–O(5)#2 O(8)–Y(1)–O(3) O(6)#1–Y(1)–O(3) O(2)–Y(1)–O(3) O(7)–Y(1)–O(3)
2.250(6) 2.262(6) 2.331(5) 2.359(5) 2.888(5) 153.9(2) 132.0(2) 73.5(2) 80.0(2) 80.75(19) 139.05(18) 77.0(2) 116.4(2) 84.0(2) 79.54(19) 85.88(19) 92.53(18) 84.58(19) 128.47(19)
Y(1)–O(5)#2 Y(1)–O(3) Y(1)–O(4) Y(1)–O(1) O(5)#2–Y(1)–O(3) O(8)–Y(1)–O(4) O(6)#1–Y(1)–O(4) O(2)–Y(1)–O(4) O(7)–Y(1)–O(4) O(5)#2–Y(1)–O(4) O(3)–Y(1)–O(4) O(8)–Y(1)–O(1) O(6)#1–Y(1)–O(1) O(2)–Y(1)–O(1) O(7)–Y(1)–O(1) O(5)#2–Y(1)–O(1) O(3)–Y(1)–O(1) O(4)–Y(1)–O(1)
2.375(5) 2.381(5) 2.462(5) 2.524(6) 144.2(2) 76.7(2) 81.32(19) 130.29(18) 74.40(17) 145.61(19) 54.11(18) 78.7(2) 125.42(19) 53.71(18) 149.24(17) 74.26(19) 71.61(19) 121.15(18)
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y + 1, z + 2; #2 x 1, y 1, z.
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3. Results and discussion 3.1. IR spectra and TG analysis The general features of the FT-IR spectra for compound 1 showing strong characteristic absorptions near 1582, 1520, and 1414 cm1 for the carboxyl groups and intense water O–H stretching vibrations (broad near 3355 cm1). The absence of a band in the region 1690–1730 cm1 (the O–H vibrations of COOH groups) suggests the complete deprotonation of carboxyl groups in compound 1. Under air environment, thermogravimetric analysis (TGA) performed on compound 1 showed a gradual weight loss of 27.79 wt% in the range of 60–120 C, which corresponds to the loss of H2O and DMF. It is slightly higher than calculated value (calcd. 24.06 wt%), which is probably due to adsorbed water molecules. The compound is compositionally stable to 350 C based on TGA measurements. At about 350 C, complete oxidation of the framework begins. A total weight loss of ca. 62% (calcd. 60.2%) shows that compound 1 is finally transformed to Y2O3.
for a tridentate carboxylate coordination. Moreover, the angles formed at the yttrium atom by the chelate rings are quite small [O1–Y1–O2, 53.77(17); O3–Y1–O4, 53.96(18); O5a–Y1–O6a, 48.88(17)]. Two inversionrelated Y atoms (Y1, Y1a) are interlinked together through two l2 bridging oxygen atoms from two carboxylate groups (Fig. 2). The Y2 unit acted as a node is connected to four adjacent nodes through six BPDC ligands to form an infinite 2-D (4,4 0 )-net with rhomboidal openings and parallel to the bc(yz) plane. Although the positions of the water hydrogen atoms could not be located, the O O sep˚ suggests the presence of hydrogen-bondaration of 2.71 A ing between the coordinated water and neighboring carboxylate. Numerous BPDC-bridged 2-D nets are further propped up by hydrogen-bond interaction along a axis direction, to afford an infinite 3-D Y-BPDC open framework (Fig. 3) where terminal DMF ligands protrude into the cavities. The apparent pore size for this kind of
3.2. X-ray single-crystal structure of compound 1 X-ray single-crystal diffraction measurements reveal that compound 1 crystallizes in the triclinic space group P-1. In the structure, yttrium ion dimers are interlinked together by BPDC ligands with two different carboxylate coordination modes, to yield 1-D channels where water and DMF molecules accommodate. As shown in Fig. 1, the Y1 center in compound 1 is nine-coordinated by one DMF molecule (O8), one water molecule (O7) and seven oxygen atoms from four BPDC carboxylic groups. Three carboxylate groups chelate the Y1 through O1, O2, O3, O4, O5a and O6a; while one other carboxylate group shares one bridging oxygen atom, O6b. The O–Y bond distances are in ˚ . It is worthy to menthe range from 2.250 (6) to 2.888 (5) A ˚ ] is considtion here that Y1-O6b bond distance [2.888(5) A ˚ erably longer than that of Y1-O6a [2.259(6) A]. It is typical
Fig. 1. ORTEP view of coordination environment of compound 1.
Fig. 2. The dimeric Y2 in [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n.
˚ ) along the crystallographic a Fig. 3. View of the 1-D channels (5 · 10 A axis in compound 1 (light green, yttrium; red, oxygen; blue, nitrogen; grey, carbon; white, hydrogen). (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)
J. Chen et al. / Microporous and Mesoporous Materials 98 (2007) 16–20 50
40 Amount cm3 [STP]g-1
channels, as measured with the distances between the adjacent Y dimer nodes and taking into account the van der Waal’s radii of those wall atoms, is approximately ˚ . Although the effective pore size is significantly 5 · 10 A diminished by the protruding DMF molecules, there is still sufficient void for DMF and water residence. The effective free volume of 1 is calculated by PLATON analysis [16] as ˚ 3 out being 12.4% (0.10 ml/g) of the crystal volume (188.7 A 3 ˚ of the 1520.9 A unit cell volume). When removing DMF and H2O molecules, its effective free volume is 33.6% ˚ 3 out of the (0.27 ml/g) of the crystal volume (510.8 A 3 ˚ 1520.9 A unit cell volume).
19
30
20
Argon 77 K Carbon dioxide 195 K Nitrogen 77 K
10
3.3. Adsorption properties of compound 1 0
0
0.2
0.4
0.6
0.8
P/P0
Fig. 5. Isotherm curves for the adsorption of N2 and Ar at 77 K, and CO2 at 195 K on compound 1.
The adsorption isotherms for MeOH and H2O were also measured. As shown in Fig. 6, type I isotherm curves are observed, which clearly indicate that compound 1 has a microporosity. It also suggests that adsorbates can move freely into the channels and that the framework retains its rigidity throughout the process. The maximum amounts of compound 1 adsorbed are 62 ml g1 for MeOH and 92 ml g1 for H2O at P/P0 = 0.9, which are equivalent to the adsorption of about 1.6MeOH and 2.4H2O per formula unit. In summary, an 3-D MOCN contained rare earth metal yttrium, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n has been prepared by liquid–liquid diffusion at room temper˚ dimension open ature. The compound contains 5 · 10 A 1-D channels along the crystallographic a axis. The compound can adsorb N2, Ar, CO2, H2O, and MeOH in the pores.
Intensity
To confirm the permanent porosity of compound 1, gas adsorption measurements were carried out by using CO2, Ar, and N2, whose kinetic diameters are known to be 3.3, ˚ , respectively [17]. Before the measurements, 3.4, and 3.64 A the sample 1 was soaked in CH2Cl2 for three days and then heated at 100 C for 12 h to remove the guest solvent molecules. X-ray powder diffraction demonstrated that the framework structure of 1 was retained upon the removal of the guest solvent molecules (Fig. 4). The adsorption measurements show that compound 1 can adsorb N2 and Ar in the pores at 77 K and also CO2 at 195 K. The sorption of N2, Ar, and CO2 revealed a type I typical isotherm for microporous materials (Fig. 5). The maximum amounts of compound 1 adsorbed are 39 cm3 g1 for N2, 43 cm3 g1 for Ar, and 40 cm3 g1 for CO2 as measured at P/P0 = 0.9. The Langmuir surface area of compound 1 are calculated to be 134, 125, and 157 m2 g1 based on the N2, Ar, and CO2 sorption studies, which are in good agreement with each other. It clearly indicates that compound 1 shows non-selectivities toward N2, Ar, and CO2.
10
20
2θ
30
40
50
Fig. 4. XRPD patterns of compound 1 before (green line) and after (red line) the removal of guest molecules. (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 6. Isotherm curves for the adsorption of MeOH and H2O at 298 K on compound 1.
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J. Chen et al. / Microporous and Mesoporous Materials 98 (2007) 16–20
Acknowledgments We are grateful for the financial support from National Nature Science Foundation of China (20233030, 20521140450 and 20421303) and Shanghai Postdoc. Foundation. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.micromeso.2006.08.015. References [1] A.C. Sudik, A.R. Millward, N.W. Ockwig, A.P. Cote, J. Kim, O.M. Yaghi, J. Am. Chem. Soc. 127 (2005) 7110. [2] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.V. Belosludov, T.C. Kobayashi, H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436 (2005) 238. [3] E.W. Bittner, B.C. Bockrath, W. Lin, Angew. Chem. Int. Ed. 44 (2005) 72.
[4] B. Chen, C. Liang, J. Yang, D.S. Contreras, Y.L. Clancy, E.B. Lobkovsky, O.M. Yaghi, S. Dai, Angew. Chem. Int. Ed. 45 (2006) 1390. [5] L. Pan, D.H. Olson, L.R. Ciemnolonski, R. Heddy, J. Li, Angew. Chem. Int. Ed. 45 (2006) 616. [6] C.-D. Wu, A. Hu, L. Zhang, W. Lin, J. Am. Chem. Soc. 127 (2005) 8940. [7] O. Ohmori, M. Fujita, Chem. Commun. (2004) 1586. [8] R.-Q. Zou, H. Sakurai, Q. Xu, Angew. Chem. Int. Ed. 45 (2006) 2542. [9] T.M. Reineke, M. Eddaoudi, M. O’Keffee, O.M. Yaghi, Angew. Chem. Int. Ed. 38 (1999) 2590. [10] B. Zhao, P. Cheng, Y. Dai, C. Cheng, D.-Z. Liao, S.-P. Yan, Z.-H. Jiang, G.-L. Wang, Angew. Chem. Int. Ed. 42 (2003) 934. [11] Y.-Q. Sun, J. Zhang, Y.-M. Chen, G.-Y. Yang, Angew. Chem. Int. Ed. 44 (2005) 5814. [12] F. Millange, C. Serre, J. Marrot, N. Gardant, F. Pelle, G. Ferey, J. Mater. Chem. 14 (2004) 642. [13] M. Knickelbein, J. Chem. Phys. 102 (1995) 1. [14] SADABS: Area-Detector Absorption Correction, Simens Industrial Automation, Inc., Madison, WI, 1996. [15] G.M. Sheldrick, SHELXS-97 and SHELXL-97, Program for X-ray Crystal Structure Solution and Refinement, Gottingen University, Germany, 1997. [16] A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7. [17] D.N. Dybtsev, H. Chun, S.-H. Yoon, D. Kim, K. Kim, J. Am. Chem. Soc. 126 (2004) 32.
Synthesis, structure, and adsorption properties of a three-dimensional porous yttrium–organic coordination network Jinxi Chen, Zhenxia Chen, Ting Yu, Linhong Weng, Bo Tu, Dongyuan Zhao
*
Molecular Catalysis and Innovative Materials Laboratory, Department of Chemistry, Advanced Materials Laboratory, Fudan University, Shanghai 200433, PR China Received 18 May 2006; received in revised form 11 August 2006; accepted 17 August 2006 Available online 26 September 2006
Abstract Deprotonation of 4,4 0 -biphenyldicarboxylic acid (H2BPDC) with triethylamine followed by the copolymerization with Y(III) in N,Ndimethylformamide (DMF) at room temperature yields a new three-dimensional (3-D) porous metal–organic coordination network, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1). Compound 1 (C24.50H19N1.50O9Y) crystallizes in the triclinic P-1 space group ˚ , a = 111.058 (5), b = 90.187 (5), c = 94.318 (5), V = 1520.9 (7) A ˚ 3, and Z = 2). X(a = 8.220 (2), b = 13.998 (4), c = 14.212 (4) A ˚ along ray crystallography reveals that 1 consists of a 3-D framework contained open 1-D channels with the dimension of 5 · 10 A the crystallographic a axis. The adsorption measurements show that compound 1 can adsorb N2, Ar and CO2 into its pores. The adsorption isotherms for MeOH and H2O were also measured. 2006 Elsevier Inc. All rights reserved. Keywords: Metal–organic coordination networks; Yttrium; Carboxylate ligands; Adsorption
1. Introduction The construction of porous metal–organic coordination networks (MOCNs) through crystal engineering has attracted much interest because of their unusual topologies and potential applications in gas adsorption [1–3], size and shape selective separation [4,5], and heterogeneous catalysis [6–8]. This class of materials can be easily obtained through self-assembly of a potentially multifunctional ligand with a metal ion that has more than one vacant or labile site. In principle, through the wide choice of metals, and the infinite choice and design of ligands, a broad range of magnetic, electrical, optical, and catalytic properties might be rationally incorporated into such materials. Seeing about a rich variety of MOCNs, transition metal elements are usually preferred over rare earth elements for the construction of MOCNs since the rare earth metals have
*
Corresponding author. Tel.: +86 21 65642036; fax: +86 21 65641740. E-mail address: [email protected] (D. Zhao).
1387-1811/$ - see front matter 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2006.08.015
high and variable coordination numbers and flexible coordination geometries. While this flexibility would make obstacles to the design of MOCNs, and also lead to exotic molecular architectures. Recently, a few lanthanide carboxylate coordination networks which endow unique magnetic and fluorescence properties have been reported [9–11]. However, until now, the yttrium–organic coordination networks are rare although yttrium is widely used in fluorescence, laser crystals, and superconductive materials [12]. In this work, we used 4,4 0 -biphenyldicarboxylic acid (H2BPDC), an extended analogue of 1,4-benzenedicarboxylic acid (H2BDC), and Y(III), one of the smallest rare earth ions to construct a new 3-D open MOCN under ambient condition. The interest of yttrium lies in facile construction of its unusual clusters [13]. Combining the larger size of BPDC as compared to that of BDC with abundant yttrium clusters may result in coordination networks with large cavity dimensions. The 3-D porous MOCN, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1) reported herein possesses 1-D open pore channels with the size of ˚ along the crystallographic a axis. It shows a 5 · 10 A
J. Chen et al. / Microporous and Mesoporous Materials 98 (2007) 16–20
microporosity with the adsorption of N2, Ar, CO2, H2O, and methanol.
17
Table 1 Crystal data and structure refinement for compound 1 1
2. Experiment section 2.1. Preparation of [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n (1) The compound 1 was prepared by liquid–liquid diffusion at room temperature. In a typical reaction, 4,4 0 -biphenyldicarboxylic acid (H2BPDC; 0.049 g, 0.2 mmol) (Aldrich) and Y(NO3)3 Æ 6H2O (0.084 g, 0.2 mmol) was dissolved in DMF (15 ml). Then a solution of triethylamine (0.2 ml) and DMF (2 ml) was allowed to diffuse slowly into the above mixture. After 2 weeks, colourless transparent crystals were obtained. Yield: 81%. C24.50H19N1.50O9Y (M = 567.32); C 51.26 (Calcd. 51.57); H 3.43 (3.86); N 3.68 (3.92)%. FT-IR (KBr pellet, cm1) 3355s, 3130s, 2454br, 1911br, 1665s, 1582s, 1520s, 1414s, 1241s, 1082m, 954s, 831s, 775s, 753s, 621w, 534m, 423w, 407m. 2.2. Characterization The CHN elemental microanalysis data were obtained using a Vario EL elemental analyzer. Infrared (IR) sample was prepared as KBr pellets, and spectra were obtained in the 4000–400 cm1 range using a Nicolet Avatar 360 FTIR spectrometer. X-ray powder diffraction (XRPD) data were collected on a Bruker D8 diffractometer with Cu Ka ˚ ). A Perkin–Elmer TGA7 thermoradiation (k = 1.5418 A gravimetric analyzer was used to obtain TGA curve in air with a heating rate of 5 C/min. The adsorption isotherms of nitrogen at 77 K, argon at 77 K, carbon dioxide at 195 K, and H2O and MeOH at room temperature were measured with BELSORP18 volumetric adsorption equipment from Bel Japan, Inc. 2.3. X-ray crystallographic measurements Single crystal (0.2 · 0.3 · 0.3 mm3) X-ray diffraction data were recorded on a Bruker SMART-APEX diffractometer equipped with a CCD detector with Mo Ka ˚ ). The raw data frames were interadiation (k = 0.71073 A grated into SHELX-format reflection files and corrected for Lorentz and polarization effects using the SAINT program and for absorption using the SADABS program [14]. Structure solution and full-matrix least-squares refinement based on F2 were performed with the SHELXS-97 and SHELXL-97 program packages [15], respectively. All non-hydrogen atoms except those from guest molecules were refined anisotropically and hydrogen P atoms were located and refined isotropically. Final R = kFojFck/ P P 2 P 2 1=2 wðF 2o Þ , with jFoj, and wRðF 2 Þ ¼ ½ wðF 2o F 2c Þ = 2 2 2 w ¼ 1=½r ðF o Þ þ ðaP Þ þ bP [where P ¼ ðMaxðF 2o ; 0Þþ 2F 2c Þ=3Þ. Details on crystal data and intensity data were given in Table 1. The selected bond distances and bond
Empirical formula Formula weight Crystal size Temperature Wavelength Crystal system Space group ˚) a (A ˚) b (A ˚) c (A a () b () c () ˚ 3) U (A Z D (calcd) (Mg m3) l (mm1) F(0 0 0) h range for data collection Limiting indices
C24.5H19N1.5O9Y 567.32 0.2 · 0.3 · 0.3 mm 298(2) K 0.71073 A Triclinic P-1 8.220(2) 13.998(4) 14.212(4) 111.058(5) 90.187(5) 94.318(5) 1520.9(7) 2 1.239 1.961 575 2.83–27.16 10 6 h 6 10, 17 6 k 6 17, 9 6 l 6 18 7669/6464 [R(int) = 0.0577] 95.6%
Reflections collected/unique Completeness to theta = 25.01 Refinement method Full-matrix least-squares on F2 Data/restraints/parameters 6464/0/321 Goodness-of-fit on F2 0.954 Final R indices [I > 2r(I)] R1,a = 0.0743, wRb2 ¼ 0:1354 R indices (all data) R1,a = 0.1863, wRb2 ¼ 0:1542 ˚ 3 Largest diff. peak and hole 0.912 and 0.419 e · A P P P P a R = kFojFck/ jFoj. wRðF 2 Þ ¼ ½ wðF 2o F 2c Þ2 = wðF 2o Þ2 1=2 . 2 w ¼ 1=½r2 ðF 2o Þ þ ð0:0150P Þ þ 0:00P ], where P ¼ ðMaxðF 2o ; 0Þ þ 2F 2c Þ=3 for 1.
angles were shown in Table 2. CCDC-196816 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge at http:// www.ccdc.cam.ac.uk/conts/retrieving.html. Table 2 ˚ ) and angles () for compound 1 Selected bond lengths (A Y(1)–O(8) Y(1)–O(6)#1 Y(1)–O(2) Y(1)–O(7) Y(1)–O(6)#2 O(8)–Y(1)–O(6)#1 O(8)–Y(1)–O(2) O(6)#1–Y(1)–O(2) O(8)–Y(1)–O(7) O(6)#1–Y(1)–O(7) O(2)–Y(1)–O(7) O(8)–Y(1)–O(5)#2 O(6)#1–Y(1)–O(5)#2 O(2)–Y(1)–O(5)#2 O(7)–Y(1)–O(5)#2 O(8)–Y(1)–O(3) O(6)#1–Y(1)–O(3) O(2)–Y(1)–O(3) O(7)–Y(1)–O(3)
2.250(6) 2.262(6) 2.331(5) 2.359(5) 2.888(5) 153.9(2) 132.0(2) 73.5(2) 80.0(2) 80.75(19) 139.05(18) 77.0(2) 116.4(2) 84.0(2) 79.54(19) 85.88(19) 92.53(18) 84.58(19) 128.47(19)
Y(1)–O(5)#2 Y(1)–O(3) Y(1)–O(4) Y(1)–O(1) O(5)#2–Y(1)–O(3) O(8)–Y(1)–O(4) O(6)#1–Y(1)–O(4) O(2)–Y(1)–O(4) O(7)–Y(1)–O(4) O(5)#2–Y(1)–O(4) O(3)–Y(1)–O(4) O(8)–Y(1)–O(1) O(6)#1–Y(1)–O(1) O(2)–Y(1)–O(1) O(7)–Y(1)–O(1) O(5)#2–Y(1)–O(1) O(3)–Y(1)–O(1) O(4)–Y(1)–O(1)
2.375(5) 2.381(5) 2.462(5) 2.524(6) 144.2(2) 76.7(2) 81.32(19) 130.29(18) 74.40(17) 145.61(19) 54.11(18) 78.7(2) 125.42(19) 53.71(18) 149.24(17) 74.26(19) 71.61(19) 121.15(18)
Symmetry transformations used to generate equivalent atoms: #1 x + 1, y + 1, z + 2; #2 x 1, y 1, z.
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3. Results and discussion 3.1. IR spectra and TG analysis The general features of the FT-IR spectra for compound 1 showing strong characteristic absorptions near 1582, 1520, and 1414 cm1 for the carboxyl groups and intense water O–H stretching vibrations (broad near 3355 cm1). The absence of a band in the region 1690–1730 cm1 (the O–H vibrations of COOH groups) suggests the complete deprotonation of carboxyl groups in compound 1. Under air environment, thermogravimetric analysis (TGA) performed on compound 1 showed a gradual weight loss of 27.79 wt% in the range of 60–120 C, which corresponds to the loss of H2O and DMF. It is slightly higher than calculated value (calcd. 24.06 wt%), which is probably due to adsorbed water molecules. The compound is compositionally stable to 350 C based on TGA measurements. At about 350 C, complete oxidation of the framework begins. A total weight loss of ca. 62% (calcd. 60.2%) shows that compound 1 is finally transformed to Y2O3.
for a tridentate carboxylate coordination. Moreover, the angles formed at the yttrium atom by the chelate rings are quite small [O1–Y1–O2, 53.77(17); O3–Y1–O4, 53.96(18); O5a–Y1–O6a, 48.88(17)]. Two inversionrelated Y atoms (Y1, Y1a) are interlinked together through two l2 bridging oxygen atoms from two carboxylate groups (Fig. 2). The Y2 unit acted as a node is connected to four adjacent nodes through six BPDC ligands to form an infinite 2-D (4,4 0 )-net with rhomboidal openings and parallel to the bc(yz) plane. Although the positions of the water hydrogen atoms could not be located, the O O sep˚ suggests the presence of hydrogen-bondaration of 2.71 A ing between the coordinated water and neighboring carboxylate. Numerous BPDC-bridged 2-D nets are further propped up by hydrogen-bond interaction along a axis direction, to afford an infinite 3-D Y-BPDC open framework (Fig. 3) where terminal DMF ligands protrude into the cavities. The apparent pore size for this kind of
3.2. X-ray single-crystal structure of compound 1 X-ray single-crystal diffraction measurements reveal that compound 1 crystallizes in the triclinic space group P-1. In the structure, yttrium ion dimers are interlinked together by BPDC ligands with two different carboxylate coordination modes, to yield 1-D channels where water and DMF molecules accommodate. As shown in Fig. 1, the Y1 center in compound 1 is nine-coordinated by one DMF molecule (O8), one water molecule (O7) and seven oxygen atoms from four BPDC carboxylic groups. Three carboxylate groups chelate the Y1 through O1, O2, O3, O4, O5a and O6a; while one other carboxylate group shares one bridging oxygen atom, O6b. The O–Y bond distances are in ˚ . It is worthy to menthe range from 2.250 (6) to 2.888 (5) A ˚ ] is considtion here that Y1-O6b bond distance [2.888(5) A ˚ erably longer than that of Y1-O6a [2.259(6) A]. It is typical
Fig. 1. ORTEP view of coordination environment of compound 1.
Fig. 2. The dimeric Y2 in [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n.
˚ ) along the crystallographic a Fig. 3. View of the 1-D channels (5 · 10 A axis in compound 1 (light green, yttrium; red, oxygen; blue, nitrogen; grey, carbon; white, hydrogen). (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)
J. Chen et al. / Microporous and Mesoporous Materials 98 (2007) 16–20 50
40 Amount cm3 [STP]g-1
channels, as measured with the distances between the adjacent Y dimer nodes and taking into account the van der Waal’s radii of those wall atoms, is approximately ˚ . Although the effective pore size is significantly 5 · 10 A diminished by the protruding DMF molecules, there is still sufficient void for DMF and water residence. The effective free volume of 1 is calculated by PLATON analysis [16] as ˚ 3 out being 12.4% (0.10 ml/g) of the crystal volume (188.7 A 3 ˚ of the 1520.9 A unit cell volume). When removing DMF and H2O molecules, its effective free volume is 33.6% ˚ 3 out of the (0.27 ml/g) of the crystal volume (510.8 A 3 ˚ 1520.9 A unit cell volume).
19
30
20
Argon 77 K Carbon dioxide 195 K Nitrogen 77 K
10
3.3. Adsorption properties of compound 1 0
0
0.2
0.4
0.6
0.8
P/P0
Fig. 5. Isotherm curves for the adsorption of N2 and Ar at 77 K, and CO2 at 195 K on compound 1.
The adsorption isotherms for MeOH and H2O were also measured. As shown in Fig. 6, type I isotherm curves are observed, which clearly indicate that compound 1 has a microporosity. It also suggests that adsorbates can move freely into the channels and that the framework retains its rigidity throughout the process. The maximum amounts of compound 1 adsorbed are 62 ml g1 for MeOH and 92 ml g1 for H2O at P/P0 = 0.9, which are equivalent to the adsorption of about 1.6MeOH and 2.4H2O per formula unit. In summary, an 3-D MOCN contained rare earth metal yttrium, [Y2(BPDC)3(DMF)2(H2O)2]n Æ (DMF)n Æ (H2O)n has been prepared by liquid–liquid diffusion at room temper˚ dimension open ature. The compound contains 5 · 10 A 1-D channels along the crystallographic a axis. The compound can adsorb N2, Ar, CO2, H2O, and MeOH in the pores.
Intensity
To confirm the permanent porosity of compound 1, gas adsorption measurements were carried out by using CO2, Ar, and N2, whose kinetic diameters are known to be 3.3, ˚ , respectively [17]. Before the measurements, 3.4, and 3.64 A the sample 1 was soaked in CH2Cl2 for three days and then heated at 100 C for 12 h to remove the guest solvent molecules. X-ray powder diffraction demonstrated that the framework structure of 1 was retained upon the removal of the guest solvent molecules (Fig. 4). The adsorption measurements show that compound 1 can adsorb N2 and Ar in the pores at 77 K and also CO2 at 195 K. The sorption of N2, Ar, and CO2 revealed a type I typical isotherm for microporous materials (Fig. 5). The maximum amounts of compound 1 adsorbed are 39 cm3 g1 for N2, 43 cm3 g1 for Ar, and 40 cm3 g1 for CO2 as measured at P/P0 = 0.9. The Langmuir surface area of compound 1 are calculated to be 134, 125, and 157 m2 g1 based on the N2, Ar, and CO2 sorption studies, which are in good agreement with each other. It clearly indicates that compound 1 shows non-selectivities toward N2, Ar, and CO2.
10
20
2θ
30
40
50
Fig. 4. XRPD patterns of compound 1 before (green line) and after (red line) the removal of guest molecules. (For interpretation of the references in colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 6. Isotherm curves for the adsorption of MeOH and H2O at 298 K on compound 1.
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Acknowledgments We are grateful for the financial support from National Nature Science Foundation of China (20233030, 20521140450 and 20421303) and Shanghai Postdoc. Foundation. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/ j.micromeso.2006.08.015. References [1] A.C. Sudik, A.R. Millward, N.W. Ockwig, A.P. Cote, J. Kim, O.M. Yaghi, J. Am. Chem. Soc. 127 (2005) 7110. [2] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.V. Belosludov, T.C. Kobayashi, H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436 (2005) 238. [3] E.W. Bittner, B.C. Bockrath, W. Lin, Angew. Chem. Int. Ed. 44 (2005) 72.
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