Two Homochiral Bimetallic Metal–Organic Frameworks Composed of

Article pubs.acs.org/crystal

Two Homochiral Bimetallic Metal−Organic Frameworks Composed of a Paramagnetic Metalloligand and Chiral Camphorates: Multifunctional Properties of Sorption, Magnetism, and Enantioselective Separation Dae Won Ryu, Woo Ram Lee, Kwang Soo Lim, Won Ju Phang, and Chang Seop Hong* Department of Chemistry, Research Institute for Natural Sciences, Korea University, Seoul 136-713, Korea S Supporting Information *

ABSTRACT: Two porous metal−organic frameworks [Co(Tt)2][Cu4(D-cam)4]·5H2O·DMF (1; Tt = tris(triazolyl)borate, D-H2cam = D-(+)-camphoric acid or (1R,3S)-1,2,2trimethyl-1,3-cyclopentanedicarboxylic acid) and [Co(Tt)2][Cu4(L-cam)4]·5H2O·2DMF (2; L-H2cam = L-(−)-camphoric acid or (1S,3R)-1,2,2-trimethyl-1,3-cyclopentanedicarboxylic acid) were prepared by mixing Cu2+, Co(Tt), and camphoric acid under solvothermal conditions. The structures of 1 and 2 reveal that the two-dimensional layers composed of chiral ligands and Cu-Cu paddlewheel units are connected through the metalloligands to form three-dimensional networks. It is noted that these solids show multifunctional properties such as gas adsorption onto the pores of the frameworks, antiferromagnetic coupling between spin carriers, and a small enantioselective separation of racemic alcohols.

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INTRODUCTION Over the past decade, metal−organic frameworks (MOFs) have attracted great attention not only because of their intriguing molecular topologies but also because of potential applications as functional materials for gas storage, molecular sensors, magnetism, luminescence, and so on.1−9 Recently, multifunctional MOFs have been a subject of intense research in materials science due to the possible creation of novel functional systems.10−16 The properties of the metal centers and linkers usually determine the function of a target material, such as its porosity and other physical properties. Among the variety of multifunctional MOFs, porous magnetic materials are a challenging subject because the materials require a combination of opposing attributes. Generally, effective magnetic coupling is highly dependent on the short bridging ligands between the spin centers, while long organic spacers are commonly used to produce MOFs with large pores.3,7,17−19 Thus, ligand design is crucial to efficiently transmit exchange interactions between the metal ions while maintaining porosity. Enantioselective separation is important in the chemical and pharmaceutical industries.20−22 Chiral MOFs are appealing because they provide stable and tunable chiral architectures. Although some homochiral MOFs have been reported in the past decade, the preparation of homochiral MOFs still remains a challenge.23−25 Currently, the effective and general method for constructing chiral MOFs uses organic enantiopure chiral ligands as building blocks.16 Specifically, the synthesis of chiral MOFs has achieved huge success by using natural organic ligands with polycarboxylate groups.26−30 © XXXX American Chemical Society

For multifunctional MOFs, it is advantageous to employ functionally different building components that provide multiple properties in a framework at once. With this strategy in mind, we chose the paramagnetic metalloligand Co(Tt)2 (Tt = tris(triazolyl)borate) and chiral camphoric acid to generate a porous magnetic MOF possessing a homochiral structure. The metalloligand Co(Tt)2 possesses exodentate sites that enable multiple coordination to thereby construct a 3D porous MOF.12,31,32 Herein, we report the syntheses, crystal structures, and physical properties of two homochiral frameworks [Co(Tt)2][Cu4(D-cam)4]·5H2O·DMF (1; D-H2cam = D(+)-camphoric acid or (1R,3S)-1,2,2-trimethyl-1,3-cyclopentanedicarboxylic acid) and [Co(Tt)2][Cu4(L-cam)4]· 5H2O·2DMF (2; L-H2cam = L-(−)-camphoric acid or (1S,3R)-1,2,2-trimethyl-1,3-cyclopentanedicarboxylic acid) (Scheme 1). It is noted that multiple functionalities of sorption, magnetism, and chiral separation coexist in a single material Scheme 1. Molecular Drawing of Chiral Camphoric Acids

Received: September 5, 2014 Revised: October 29, 2014

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Figure 1. (a) Molecular structure of [Co(Tt)2]. (b) Side view of the [Co(Tt)2][Cu2(D-cam)2]4 unit. Extended 2D layer in (c) 1 and (d) 2, showing the paddlewheel units with four connections. The dotted circles indicate the different methyl positions of the camphoric acids; the methyl group in 1 is located below the cyclopentyl ring, while the methyl group in 2 is situated above the ring. Thermo Nicolet 380 spectrometer. Thermogravimetric analyses were carried out at a ramp rate of 10 °C/min in a N2 flow using a Scinco TGA N-1000 instrument. Powder X-ray diffraction (PXRD) data were recorded using Cu Kα (λ = 1.5406 Å) radiation on a Rigaku Ultima III diffractometer with a scan rate of 2°/min and a step size of 0.02°. Circular dichroism (CD) spectra were recorded using a Jasco J-810 spectropolarimeter. Magnetic susceptibilities for 1 and 2 were carried out using a Quantum Design SQUID susceptometer. Diamagnetic corrections of all samples were estimated from Pascal’s Tables. Gas Sorption Measurements. For gas sorption, 1 and 2 were immersed in CHCl3 for 3 days to exchange the guest solvents with chloroform. After the resultant mixtures were filtered and washed with ether, desolvated samples of 1′ and 2′ were collected by heating at 100 °C under vacuum for 4 h. Gas sorption isotherms were measured using a BEL Belsorp mini II gas adsorption instrument with up to 1 atm of gas pressure. Highly pure N2 (99.999%), H2 (99.999%), and CO2 (99.999%) were used in the sorption experiments. N2 and H2 gas isotherms were measured at 77 K, and CO2 isotherms were measured at 195, 273, and 298 K. Crystallographic Structure Determination. Crystals of 1 and 2 were mounted on a cryoloop under a cooling stream of nitrogen gas. Diffraction data were collected using synchrotron radiation by a 6B MX-I ADSC Quantum-210 detector with a silicon (111) double crystal monochromator at the Pohang Accelerator Laboratory. The ADSC Quantum-210 ADX program (Ver. 1.92) was used for data collection, and HKL2000 (Ver. 0.98.699) was used for cell refinement, data reduction, and absorption corrections. The structure was solved by direct methods and refined by full-matrix least-squares analysis

because magnetic and chiral building blocks play a role in the construction of the porous framework.

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EXPERIMENTAL SECTION

Reagent. Co(Tt)2 (Tt = tris(triazolyl)borate) was prepared according to the literature procedure.33 All other chemicals and solvents used in the synthesis were of reagent grade and used as received. [Co(Tt)2][Cu4(D-cam)4]·5H2O·DMF (1). Co(Tt)2 (0.04 mmol), CuCl2·2H2O (0.16 mmol), and D-H2cam (0.16 mmol) were dissolved in 5 mL of a mixed solvent (DMF:H2O:isopropyl alcohol = 3:3:1, v/v) and stirred for 10 min. The solution was filtered and transferred to a vial. The vial was capped and placed in an oven at 100 °C for 2 days. Green crystals were obtained after filtration and dried in air. Yield: 40%. Anal. Calcd for C55H87B2CoCu4N19O22: C, 38.83; H, 5.15; N, 15.64. Found: C, 39.12; H, 4.92; N, 15.74. [Co(Tt)2][Cu4(L-cam)4]·5H2O·2DMF (2). Co(Tt)2 (0.04 mmol), CuCl2·2H2O (0.16 mmol), and L-H2cam (0.16 mmol) were dissolved in 5 mL of a mixed solvent (DMF:H2O:isopropyl alcohol = 3:3:1, v/ v). The clear mixture was stirred for 10 min, and the filtered solution was transferred to a vial. The sealed vial was placed in an oven at 100 °C for 2 days. Green crystals were filtered and dried in air to produce 2. Yield: 40%. Anal. Calcd for C58H94B2CoCu4N20O23: C, 39.03; H, 5.68; N, 15.65. Found: C, 39.26; H, 5.34; N, 15.79. Physical Measurements. Elemental analyses for C, H, and N were performed at the Elemental Analysis Service Center of Sogang University. Infrared spectra were obtained from KBr pellets with a B

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Figure 2. (a) Extended structure of 1 in the ab plane where 2D sheets are connected by [Co(Tt)2]. (b) Connolly surface of 1 with a probe radius of 1.4 Å showing the 1D channels.

to a Jahn−Teller elongation.32,34,36 A pair of Cu(II) centers is bridged by four carboxylates, forming a paddlewheel-shaped Cu2(CO2)4 cluster unit. The Cu−Cu distances within the dimeric Cu2 subunits are 2.6464(12) Å for Cu1−Cu2 and 2.6313(13) Å for Cu3−Cu4. Furthermore, each Cu2(CO2)4 paddlewheel cluster is connected to four other paddlewheel clusters by camphorates in the equatorial direction, resulting in a 2D sheet (Figure 1c). The existence of the chiral D-cam in 1 causes the methyl group to be positioned below the cyclopentyl ring, compared with L-cam in 2 where the methyl group lies above the ring (Figure 1c,d). The Co(Tt)2 metalloligand acts as a pillar to cross-link the 2D sheets into noninterpenetrating 3D architectures (Figure 2a). Notably, 1D porous channels are visible along the crystallographic c axis (Figures 2b and S1, Supporting Information). The window size of the 1D channel is approximated as 5.0 × 10.5 Å, after taking into account the van der Waals surface of the backbone. The accessible void volume per unit cell volume is calculated to be 30.8% using PLATON.37 To simplify the network structure, the midpoints of the Cu dimers and positions of the Co atoms are represented by joints, which are linked by triazoles and camphorates expressed as sticks (Figure S2, Supporting Information). From a topological analysis, 1 constitutes a 3D 2-nodal framework. The 4,6-c net with a (4-c)(6-c)2 stoichiometry forms the point symbol {32.44.54.64.7}2{32.64}, leading to a topology type of sqc124.38 Other camphorate-based chiral MOFs were also reported, which demonstrate interesting structural features.39−41 Thermal and Structural Stabilities. We recorded thermogravimetric (TG) data over a temperature range of 25−700 °C to examine the thermal stabilities of 1 and 2 (Figure S3, Supporting Information). The TG curve of 1 suggests that guest molecules (approximately 7 H2O and 1 DMF) are released from the framework in the temperature range of 30−200 °C (expt. 11.4 wt %, calcd. 11.5 wt %). To exchange the lattice solvent molecules, the as-prepared sample was soaked in chloroform for 2 days. The guest molecules in the pore were successfully replaced with chloroform, as confirmed by TG data. To obtain the desolvated sample, the CHCl3-exchanged sample was heated at 100 °C under vacuum for 3 h. Although the desolvated framework rapidly adsorbed

using anisotropic thermal parameters for non-hydrogen atoms with the SHELXTL program.35 Some carbon atoms were disordered over two sites with occupancies of 0.5 and isotropically refined. Lattice water and DMF molecules in 1 and 2 were significantly disordered and could not be modeled properly; thus, the program SQUEEZE, a part of the PLATON37 package of crystallographic software, was used to calculate the solvent disorder area and remove its contribution to the overall intensity data. All hydrogen atoms were calculated at idealized positions and refined using a riding model. Crystal data of 1(squeezed): empirical formula = C52H70B2CoCu4N18O16, Mr = 1537.97, monoclinic, space group C2, a = 26.676(5) Å, b = 18.145(4) Å, c = 18.954(4) Å, β = 118.54(3)°, V = 8059(3) Å3, Z = 4, Dcalc = 1.268 g cm−3, μ = 1.303 mm−1, Flack parameter = −0.028(15), 32 597 reflections collected, 22 650 unique (Rint = 0.0550), R1 = 0.0726, wR2 = 0.2032 [I > 2σ(I)]. Crystal data of 2(squeezed): empirical formula = C52H70B2CoCu4N18O16, Mr = 1537.97, monoclinic, space group C2, a = 26.604(5) Å, b = 18.113(4) Å, c = 18.925(4) Å, β = 118.24(3)°, V = 8034(3) Å3, Z = 4, Dcalc = 1.272 g cm−3, μ = 1.307 mm−1, Flack parameter = 0.03(2), 21 577 reflections collected, 14 012 unique (Rint = 0.0669), R1 = 0.0811, wR2 = 0.2290 [I > 2σ(I)].

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RESULTS AND DISCUSSION Description of Crystal Structures. Complexes 1 and 2 were synthesized in the same reaction conditions using D(+)-camphoric acid and L-(−)-camphoric acid, respectively. Single-crystal X-ray diffraction analysis reveals that complexes 1 and 2 crystallize in the monoclinic system with the chiral space group C2. As the overall crystal structure of 1 is similar to that of 2, we describe the detailed geometric features of 1 only. In the molecular view of 1, the metalloligand Co(Tt)2 is sandwiched between two tripodal Tt groups (Figure 1a). The Co−N distances in the octahedral environment range from 2.082(5) to 2.200(5) Å. Among the six exodentate N sites, four coordinate to the axial positions of neighboring Cu atoms (Figure 1b). The binding mode of exodentate N donors in Co(Tt)2 is similar to that in a porous Cu(Tt)2−Mn complex32 but different from those in other 3D M(Tt)-based bimetallic systems.12,31 Each Cu(II) ion adopts a square-pyramidal coordination geometry consisting of four equatorial O atoms from the four bridging carboxylates of the four independent Dcam moieties along with one apical N atom from the Co(Tt)2 ligand. The axial Cu−N(triazole) bond distances span from 2.106(6) to 2.196(6) Å, which are larger than the equatorial Cu−O lengths (1.909(5)−2.028(6) Å), which can be attributed C

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water from the atmosphere, it was stable up to 260 °C (Figure S3a). We measured PXRD data of the as-prepared, CHCl3exchanged, and desolvated samples (Figure S4, Supporting Information). All major peaks of the experimental PXRD profiles of 1 match well with the simulated pattern, indicating that the original phase is maintained during the solvation and activation processes. The temperature-dependent PXRD data of 1 show that sharp and intense peaks are retained until 250 °C, suggesting the structural stability of the 3D compound in the given temperature range (Figure S5, Supporting Information). The TG graph of 2 also reveals that the thermal stability of 1 is analogous to that of 2, which originates from the structural similarity (Figure S3b). The guest molecules (approximately 5 H2O and 2 DMF) in 2 are eliminated in the temperature range of 30−200 °C (expt. 13.1 wt %, calcd. 13.3 wt %). After desolvation, the framework of 2 remains intact, as corroborated by the PXRD data (Figure S4). Gas Sorption. N2 gas adsorption and desorption isotherms of 1 and 2 were measured at 77 K (Figure 3). The Brunauer

Supporting Information). Interestingly, a significant hysteresis is manifest in the adsorption isotherm at 195 K. The large hysteresis may pertain to the flexibility of the frameworks.18,43−45 Using the virial equation fitting parameters obtained from the adsorption data measured at 273 and 298 K, the isosteric heats of CO2 adsorption at zero coverage are estimated to be −21.5 kJ mol−1 for 1 and −24.3 kJ mol−1 for 2 (Figures S13−S16, Supporting Information), which are similar to those of other MOFs.46 Magnetic Properties. Magnetic data for 1 and 2 were collected as a function of temperature and field (Figure 4). The

Figure 4. Plot of χmT versus T for (a) 1 and (b) 2 at 1000 G. Plot of M versus H for (c) 1 and (d) 2 at 2 K.

χmT values of 1 and 2 at 300 K are 2.67 and 2.68 cm3 K mol−1, respectively, which are much smaller than the theoretical value (3.375 cm3 K mol−1) calculated from one Co(II) (SCo = 3/2) and four Cu(II) (SCu = 1/2). This feature is a combined consequence of strong antiferromagnetic interactions between Cu ions within the Cu2(CO2)4 paddlewheel cluster and the unquenched orbital angular moment of the octahedral highspin Co(II) center. The antiferromagnetic coupling in the Cu2 dimer results from the magnetic orbitals of Cu dx2−y2 that are subject to superexchange interactions through the carboxylate bridges. The gradual decrease in χmT with decreasing temperature is associated not only with the strong antiferromagnetic contribution of the Cu−Cu pair but also with the spin−orbit coupling of the Co(II) ion. Further cooling of the sample below 9 K causes the χmT value to decrease more sharply. Since, at such low temperature, the strong antiferromagnetic exchange coupling forces Cu spins in the dimeric subunit to be paired up,47 the drastic reduction in χmT can be explained by the fact that adjacent Co(II) spins below 9 K are coupled in an antiferromagnetic manner, albeit weakly. In the magnetization curves, the saturation magnetizations at 7 T amount to 1.60 Nβ for 1 and 1.62 Nβ for 2. Considering that Co(II) is saturated in the range of 2.3−2.4 Nβ,48 the observed value is much smaller than expected. This disparity verifies the existence of antiferromagnetic interactions between Co(II) ions throughout the lattice, which is also consistent with the decline of the χmT product below 9 K. Chiral Separation. The CD curve of 1 is a mirror image of that of 2, which identifies their enantiomeric nature (Figure S17, Supporting Information). To investigate the chiral separation capabilities, 1-phenylethanol was selected as an

Figure 3. (a) N2 and (b) H2 isotherms for 1′ and 2′ at 77 K.

Emmett−Teller (BET) surface areas of 1 and 2 are similar, which are estimated as 472 m2 g−1 for 1 and 488 m2 g−1 for 2 from the N2 adsorption isotherms. The H2 sorption capacities of 1 and 2 reach 103 cm3 g−1 (0.92 wt %) and 110 cm3 g−1 (0.99 wt %), respectively, at 1 bar and 77 K (Figure S6, Supporting Information). In the H2 sorption isotherms, no hysteresis upon adsorption or desorption is detected. An additional hydrogen isotherm at 87 K was collected to calculate the isosteric heat of adsorption by fitting with a virial-type equation (Figures S7 and S8, Supporting Information). The adsorption enthalpy is −9.6 kJ mol−1 for 1 and −9.9 kJ mol−1 for 2 (Figures S9 and S10, Supporting Information), which are in the range of some carboxylate-bridged MOFs.42 The CO2 adsorption isotherms of 1 and 2 were measured at different temperatures of 195, 273, and 298 K (Figures S11 and S12, D

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alities such as sorption properties, antiferromagnetic couplings, and a small enantioselective separation ability of racemic alcohols.

analyte. Compound 1′ was immersed in racemic 1-phenylethanol at room temperature for 3 days. Thereafter, the solid was filtered and washed several times with dry diethyl ether to remove any alcohols adsorbed on the solid surface. We then extracted the remaining alcohol from the pore by soaking the solid in dry MeOH for 3 days. The filtered liquid was analyzed by HPLC to inspect the released alcohol. A trace of the encapsulated 1-phenylethanol in the methanol solution was analyzed on an OD-H column with a flow rate of 0.5 mL min−1 using an eluent of 95:5 hexane:isopropanol. By this method, 1 shows a small chiral separation for 1-phenylethanol with an ee of 13.8% (Figure 5a,b). This feature should be associated with

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ASSOCIATED CONTENT

S Supporting Information *

X-ray crystallographic files in CIF format and additional experimental data for the complexes. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] (C.S.H.). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the Korea CCS R&D Center (KCRC) grant funded by the Korea government (The Ministry of Science, ICT & Future Planning (MSIP)) (NRF2014M1A8A1049253), the Basic Science Research Program (NRF-2012R1A1A2007141), and the Priority Research Centers Program (NRF20100020209). We thank Prof. C.-H. Cheon in Korea University and Dr. E. K. Koh in KBSI for allowing us to have access to HPLC and SQUID instruments, respectively.

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REFERENCES

(1) Yaghi, O. M.; O’Keeffe, M.; Ockwig, N. W.; Chae, H. K.; Eddaoudi, M.; Kim, J. Nature 2003, 423, 705. (2) Papaefstathiou, G. S.; MacGillivray, L. R. Coord. Chem. Rev. 2003, 246, 169. (3) Kitagawa, S.; Uemura, K. Chem. Soc. Rev. 2005, 34, 109. (4) Kuppler, R. J.; Timmons, D. J.; Fang, Q.-R.; Li, J.-R.; Makal, T. A.; Young, M. D.; Yuan, D.; Zhao, D.; Zhuang, W.; Zhou, H.-C. Coord. Chem. Rev. 2009, 253, 3042. (5) Stock, N.; Biswas, S. Chem. Rev. 2012, 112, 933. (6) Tan, J. C.; Cheetham, A. K. Chem. Soc. Rev. 2011, 40, 1059. (7) Dechambenoit, P.; Long, J. R. Chem. Soc. Rev. 2011, 40, 3249. (8) Cui, Y.; Yue, Y.; Qian, G.; Chen, B. Chem. Rev. 2012, 112, 1126. (9) Cook, T. R.; Zheng, Y. R.; Stang, P. J. Chem. Rev. 2013, 113, 734. (10) Kanoo, P.; Gurunatha, K. L.; Maji, T. K. J. Mater. Chem. 2010, 20, 1322. (11) Lee, J.; Farha, O. K.; Roberts, J.; Scheidt, K. A.; Nguyen, S. T.; Hupp, J. T. Chem. Soc. Rev. 2009, 38, 1450. (12) Ryu, D. W.; Lee, W. R.; Lee, J. W.; Yoon, J. H.; Kim, H. C.; Koh, E. K.; Hong, C. S. Chem. Commun. 2010, 46, 8779. (13) Agustí, G.; Ohtani, R.; Yoneda, K.; Gaspar, A. B.; Ohba, M.; Sánchez-Royo, J. F.; Muñoz, M. C.; Kitagawa, S.; Real, J. A. Angew. Chem., Int. Ed. 2009, 48, 8944. (14) Duriska, M. B.; Neville, S. M.; Lu, J.; Iremonger, S. S.; Boas, J. F.; Kepert, C. J.; Batten, S. R. Angew. Chem., Int. Ed. 2009, 48, 8919. (15) Ma, L.; Abney, C.; Lin, W. Chem. Soc. Rev. 2009, 38, 1248. (16) Qiu, S.; Zhu, G. Coord. Chem. Rev. 2009, 253, 2891. (17) Kar, P.; Haldar, R.; Gómez-García, C. J.; Ghosh, A. Inorg. Chem. 2012, 51, 4265. (18) Férey, G.; Serre, C. Chem. Soc. Rev. 2009, 38, 1380. (19) Ohba, M.; Yoneda, K.; Agusti, G.; Muñoz, M. C.; Gaspar, A. B.; Real, J. A.; Yamasaki, M.; Ando, H.; Nakao, Y.; Sakaki, S.; Kitagawa, S. Angew. Chem., Int. Ed. 2009, 48, 4767. (20) Lin, W.; Rieter, W. J.; Taylor, K. M. Angew. Chem., Int. Ed. 2009, 48, 650. (21) Rieter, W. J.; Pott, K. M.; Taylor, K. M. L.; Lin, W. J. Am. Chem. Soc. 2008, 130, 11584. (22) Wu, P.; He, C.; Wang, J.; Peng, X.; Li, X.; An, Y.; Duan, C. J. Am. Chem. Soc. 2012, 134, 14991.

Figure 5. HPLC graph for rac-1-phenylethanol (a) before and (b) after chiral separation of 1-phenylethanol by 1. HPLC data for rac-2phenyl-1-propanol (c) before and (d) after chiral separation of 2phenyl-1-propanol by 1.

the fact that the framework topology is based on the homochiral 2D layers linked by enantiopure D-camphorates. As reported in the literature,23 alcohol molecules should not couple with the frameworks, but rather be positioned in the chiral spaces of the pores, giving rise to the enantioselective separation of the probe molecule by the homochiral MOFs (Figure S18, Supporting Information). Thus, the low enantioselectivity of 1 may arise from the poor match between the chiral pore environment and the tested alcohol, although the size of the alcohol is suitable to pass through the dimensions of the pore window.23 In addition, 1-phenyl-2propanol was also measured on an OB-H column with a flow rate of 0.5 mL min−1 using an eluent of 93:7 hexane:isopropanol. However, 1-phenyl-2-propanol was not selectively separated (Figure 5c,d). It is speculated that the penetration of guest molecules along the pore is not efficient due to its size.24,28

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CONCLUSIONS Two porous frameworks, 1 and 2, were prepared by reacting the paramagnetic metalloligand Co(Tt)2 and chiral camphoric acid in the presence of Cu(II) metal ions under solvothermal conditions. In the crystal structures of 1 and 2, the twodimensional layers are constructed by chiral ligands and a Cu− Cu paddlewheel unit, leading to the formation of a threedimensional network with the assistance of metalloligand bridges. Notably, these compounds demonstrate multifunctionE

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(23) Xiang, S. C.; Zhang, Z.; Zhao, C. G.; Hong, K.; Zhao, X.; Ding, D. R.; Xie, M. H.; Wu, C. D.; Das, M. C.; Gill, R.; Thomas, K. M.; Chen, B. Nat. Commun. 2011, 2, 204. (24) Das, M. C.; Guo, Q.; He, Y.; Kim, J.; Zhao, C. G.; Hong, K.; Xiang, S.; Zhang, Z.; Thomas, K. M.; Krishna, R.; Chen, B. J. Am. Chem. Soc. 2012, 134, 8703. (25) Li, Z. J.; Yao, J.; Tao, Q.; Jiang, L.; Lu, T. B. Inorg. Chem. 2013, 52, 11694. (26) Zhang, J.; Chen, S.; Valle, H.; Wong, M.; Austria, C.; Cruz, M.; Bu, X. J. Am. Chem. Soc. 2007, 129, 14168. (27) Zhang, J.; Chen, S.; Zingiryan, A.; Bu, X. J. Am. Chem. Soc. 2008, 130, 17246. (28) Lin, L.; Yu, R.; Wu, X. Y.; Yang, W. B.; Zhang, J.; Guo, X. G.; Lin, Z. J.; Lu, C. Z. Inorg. Chem. 2014, 53, 4794. (29) Yang, P.; He, X.; Li, M.-X.; Ye, Q.; Ge, J.-Z.; Wang, Z.-X.; Zhu, S.-R.; Shao, M.; Cai, H.-L. J. Mater. Chem. 2012, 22, 2398. (30) Wang, L.; Song, T.; Huang, L.; Xu, J.; Li, C.; Ji, C.; Shan, L.; Wang, L. CrystEngComm 2011, 13, 4005. (31) Youm, K. T.; Kim, M. G.; Ko, J.; Jun, M. J. Angew. Chem. 2006, 45, 4003. (32) Ryu, D. W.; Shin, J. H.; Lim, K. S.; Lee, W. R.; Phang, W. J.; Yoon, S. W.; Suh, B. J.; Koh, E. K.; Hong, C. S. Dalton Trans. 2014, 43, 6994. (33) Janiak, C. Chem. Ber. 1994, 127, 1379. (34) Lim, J. H.; You, Y. S.; Yoo, H. S.; Yoon, J. H.; Kim, J. I.; Koh, E. K.; Hong, C. S. Inorg. Chem. 2007, 46, 10578. (35) Sheldrick, G. M. SHELXTL, version 5, Bruker AXS: Madison, Wisconsin, 1995. (36) Lim, J. H.; Kang, J. S.; Kim, H. C.; Koh, E. K.; Hong, C. S. Inorg. Chem. 2006, 45, 7821. (37) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool; Utrecht University: The Netherlands, 2005. (38) Blatov, V. A.; Shevchenko, A. P. TOPOS (Ver. 4.0); Samara State University: Samara, Russia, 2011. (39) Dang, D.-B.; An, B.; Bai, Y.; Zheng, G.-S.; Niu, J.-Y. Chem. Commun. 2013, 49, 2243. (40) Zhang, J.; Yao, Y.-G.; Bu, X. Chem. Mater. 2007, 19, 5083. (41) Zhang, J.; Bu, X. Angew. Chem., Int. Ed. 2007, 46, 6115. (42) Suh, M. P.; Park, H. J.; Prasad, T. K.; Lim, D. W. Chem. Rev. 2012, 112, 782. (43) Choi, H. S.; Suh, M. P. Angew. Chem., Int. Ed. 2009, 48, 6865. (44) Kaneko, K.; Ohba, M.; Kitagawa, S. J. Am. Chem. Soc. 2007, 129, 13706. (45) Choi, H. J.; Dincă, M.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 7848. (46) Sumida, K.; Rogow, D. L.; Mason, J. A.; McDonald, T. M.; Bloch, E. D.; Herm, Z. R.; Bae, T. H.; Long, J. R. Chem. Rev. 2012, 112, 724. (47) Figgis, B. N.; Martin, R. L. J. Chem. Soc. 1956, 3837. (48) Kurmoo, M. Chem. Soc. Rev. 2009, 38, 1353.

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