Three Two-Folded Interpenetrating 3D Metal–Organic Frameworks

ARTICLE pubs.acs.org/crystal

Three Two-Folded Interpenetrating 3D Metal
Organic Frameworks Consisting of Dinuclear Metal Units: Syntheses, Structures, and Magnetic Properties Xiaoju Li,*,†,‡ Yuanzhu Cai,† Zhenlan Fang,‡ Lijian Wu,† Bin Wei,† and Shen Lin*,† †

Fujian Key Laboratory of Polymer Materials, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, People's Republic of China ‡ State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, People's Republic of China

bS Supporting Information ABSTRACT: Three two-folded interpenetrating 3D coordination polymers, [M(ip-OH)(Bimb)0.5]n [where M = Ni(II) (1), Co(II) (2), or Cu(II) (3); H2ip-OH = 5-hydroxylisophthalic acid; and Bimb =1,4-bis(imidazol-10 -yl)butane], were synthesized by hydrothermal reactions of H2ip-OH, Bimb, and MCl2 in the presence of base. Single-crystal X-ray diffraction studies reveal that 1
3 consist of dinuclear metal units, which are bridged by ip-OH to form [M(ip-OH)]n layers and are further pillared by Bimb to generate 3D α-Po networks. Bimb adopts a gauche
antigauche conformation. Both the large void in the 3D network and the hydrogen bonds between hydroxyl of ip-OH and one carboxylate oxygen atom from the other network result in the formation of two-folded interpenetrating architectures. The secondary building units in 1
3 are well separated by ipOH and Bimb. The magnetic data of 1
3 were fitted to the dimeric modes; fitting results indicate antiferromagnetic exchange between metal centers in the dinuclear metal units.

’ INTRODUCTION Great progrss has been made in the rational design and synthesis of metal
organic frameworks (MOFs) containing paramagnetic and diamagnetic centers, which have intriguing structural topologies and potential application as magnetic materials.1
3 Current efforts are devoted to the development of synthetic routes for assemblying well-characterized di- or polynuclear metal clusters into the extended coordination networks, in which metal clusters as secondary building units (SBUs) are held together by multidentate bridging ligands with specific coordination groups and suitable spacers.4
8 The coordination groups in the bridging ligands are capable of forming SBUs and transmitting magnetic interactions, while the spacers can separate SBUs to reduce magnetic coupling among the adjacent SBUs. In this respect, rigid di- or polycarboxylate ligands have been extensively employed in the construction of MOFs based on carboxylate-bridged SBUs.6
8 For example, various predictable porous MOFs based on tetracarboxylate-bridged dimetallic paddlewheel SBUs have been generated in which the positive charge from the metal ions is compensated by carboxylate groups; this mitigates the counterion effect in the selfassembly process.6 However, the carboxylate group possesses various coordination modes, allowing for the formation of diverse carboxylate
metal clusters and transmission of magnetic coupling in different degrees. Moreover, the size, shape, length, and conformation of the spacers in the carboxylate ligands also r 2011 American Chemical Society

affect the mediation of magnetic coupling and construction of MOFs.8,9 These factors complicate the magnetic exchange and structural prediction of final products. Thus, the design of MOFs based on bi- or polynuclear metal units with predictable magnetic properties is still a challenge in the fields of molecular magnetism and crystal engineering. One of our approaches for preparing the extended MOFs is the incorporation of nitrogen-containing bridging ligands with long spacers into the metal
carboxylate system.10,11 The basic synthetic aim is to further minimize intercluster magnetic exchange and to elongate SBUs into higher-dimensional networks. In comparison with rigid nitrogen-containing ligands with a single conformation (such as 4,4-bipyridine),12 the flexible ligands may adopt several conformations to satisfy coordination geometries of metal ions; this may result in new SBUs and generate interpenetrating MOFs with novel structures and properties.13,14 In this context, imidazolyl ligands are promising building units owing to their simple synthetic procedures and strong coordination ability with transition metal ions. In our previous study, we have reported Co(II) and Cu(II) complexes from 1,2-bis(imidazol-10 -yl)ethane (Bime) and 5-hydroxylisophthalic acid (H2ip-OH). Both complexes possess well-isolated Received: June 9, 2011 Revised: August 12, 2011 Published: September 02, 2011 4517

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Table 1. Crystal Data and Structural Refinement Results in Complexes 1
3 1

’ EXPERIMENTAL SECTION Materials and General Methods. Bimb was synthesized accord-

C13H11NiN2O5 C13H11CoN2O5 C13H11CuN2O5

formula weight crystal system

333.95 monoclinic

334.17 monoclinic

338.78 monoclinic

space group

P2(1)/n

P2(1)/n

P2(1)/n

a(Å)

8.238

8.232(3)

8.053

b(Å)

15.232

15.432(6)

15.850

c(Å)

10.754

10.804(4)

10.762

β (deg)

97.902(4)

98.440(7)

99.610(4)

V (Å3)

1336.7(1)

1357.7(9)

1354.4

Z Fcalcd (g/cm3)

4 1.659

4 1.635

4 1.661

μ (mm
1)

1.475

1.287

1.636

F(000)

684

680

688

reflns collected

7981

10 322

10 335

unique reflns

2362

3103

3093

Rint

0.0231

0.0351

0.0371

parameters

190

190

198

GOF R1 [I > 2σ(I)]a

1.045 0.0321

1.050 0.0423

1.078 0.0361

wR2 (all data)b

0.0744

ΔFmax, ΔFmin [e/Å3] 0.751,
0.684 a

3

0.0933

0.0973

0.939,
0.906

0.654,
0.405

R1 = ∑ Fo|
|Fc /∑|Fo|. b wR2 = {∑[w(Fo2
Fc2)2/∑[w(Fo2)2]]1/2. )

ing to the reported literature procedure.15 Other chemicals were obtained from commercial sources and were used without further purification. IR spectra (KBr pellets) were recorded on a Magna 750 Fourier transform infrared (FT-IR) spectrophotometer in the range 400
4000 cm
1. C, H, and N elemental analyses were determined on an EA1110 CHNS-0 CE element analyzer. Powder X-ray diffraction data were recorded on a PANaytical X’pert pro X-ray diffractometer with graphite-monochromatized Cu Kα radiation (λ = 1.542 Å). Thermal stability studies were carried out on a Netschz STA 449C thermoanalyzer under N2 (30
1200 °C range) at a heating rate of 10 °C/min. Polycrystalline magnetic susceptibility data were collected on a Quantum Design MPMS model 6000 magnetometer in the temperature range 2
300 K. Synthesis of [Ni(ip-OH)(Bimb)0.5]n (1). A mixture of NiCl2 3 6 H2O (60.0 mg, 0.25 mmol), H2ip-OH (45.5 mg, 0.25 mmol), Bimb (47.6 mg, 0.25 mmol), NaOCH3 (27.0 mg, 0.5 mmol), and deionized water (10 mL) was placed in a Parr Teflon-lined stainless steel vessel (20 mL) and was stirred at room temperature for 5 h. The mixture was then heated at 160 °C for 48 h, followed by slow cooling to room temperature at a rate of 6 °C/h. Green block crystals of 1 were collected, washed with H2O, and air-dried. Yield 43.4 mg, 53% based on NiCl2 3 6H2O. IR (KBr, cm
1) 3291 (m), 3137 (vw), 1801 (vw), 1613 (w), 1565 (s), 1543 (w), 1523 (vw), 1492 (w), 1455 (w), 1417 (m), 1391 (s), 1295 (vw), 1282 (s), 1235 (vw), 1216 (w), 1104 (s), 1033 (w), 1001 (w), 976 (m), 955 (w), 897 (w), 838 (m), 807 (w), 781 (m), 735 (m), 678 (m), 654 (w), 494 (w). Anal. Calcd for C13H11NiN2O5 (333.95): C, 46.71; H, 3.29; N, 8.38. Found: C, 47.16; H, 3.52; N, 8.19. Synthesis of [Co(ip-OH)(Bimb)0.5]n (2). A mixture of CoCl2 3 6 H2O (60.0 mg, 0.25 mmol), H2ip-OH (45.5 mg, 0.25 mmol), Bimb (47.6 mg, 0.25 mmol), NaOCH3 (14.0 mg, 0.25 mmol), and deionized water (12 mL) was placed in a Parr Teflon-lined stainless steel vessel (20 mL) and was stirred at room temperature for 5 h. The mixture was then heated at 160 °C for 48 h, followed by slow cooling to room temperature at a rate of 6 °C/h. Pink block crystals of 2 were collected, washed with H2O, and air-dried. Yield 51.7 mg, 62% based on CoCl2 3 6H2O. IR (KBr, cm
1) 3293 (m), 3136 (vw), 2947 (vw), 1803 (vw), 1618 (w), 1567(s), 1541 (w), 1496 (w), 1454 (w), 1417 (m), 1392 (s), 1294 (vw), 1280 (m), 1237 (vw), 1128 (vw), 1217(w), 1105 (s), 1034 (w), 1001 (w), 976 (m), 955 (w), 897 (w), 835 (m), 802 (w), 777 (m), 735 (m), 677 (m), 652 (w), 494 (w). Anal. Calcd for C13H11CoN2O5 (334.17): C, 46.68; H, 3.29; N, 8.38. Found: C, 46.87; H, 3.42; N, 8.03. Synthesis of [Cu(ip-OH)(Bimb)0.5]n (3). A mixture of CuCl2 3 2 H2O (42.6 mg, 0.25 mmol), H2ip-OH (36.4 mg, 0.20 mmol), Bimb

2

formula

)

metal
carboxylate chains and interesting magnetic behaviors.10c As a continuation of our efforts in the construction of magnetic MOFs from rigid carboxylate ligands and flexile imidazoyl ligands, we are interested in more flexible 1,4-bis(imidazol-10 -yl)butane (Bimb). The more flexible nature of the butyl spacer between imidazolyl rings may allow it to freely bend and rotate when Bimb coordinates to metal centers, which may result in distinct structural topologies.11,15 Moreover, as the length of the spacer increases, intriguing interpenetration may be adopted by nature in order to avoid the formation of large open channels or cavities. Herein, we report the syntheses, structures, and magnetic properties of three 3D coordination polymers, [M(ip-OH)(Bimb)0.5]n [where M = Ni(II) (1), Co(II) (2), or Cu(II) (3)]. The three complexes are two-folded interpenetrating 3D networks with dinuclear metal units as nodes and organic ligands as spacers. Magnetic measurements show that they possess antiferromagnetic properties.

ARTICLE

(38.0 mg, 0.20 mmol), NaOH (1 M, 1 drop), and deionized water (12 mL) was placed in a Parr Teflon-lined stainless steel vessel (20 mL) and was stirred at room temperature for 5 h. The mixture was then heated at 160 °C for 48 h, followed by slow cooling to room temperature at a rate of 6 °C/h. Blue block crystals of 3 were collected, washed with H2O, and air-dried. Yield 34.5 mg, 51% based on Bimb. IR (KBr, cm
1) 3298 (m), 3137 (vw), 2946 (vw), 1801 (vw), 1622 (m), 1580 (s), 1530 (m), 1490 (m), 1447 (w), 1419 (s), 1396 (s), 1350 (vw), 1296 (vw), 1277 (s), 1235 (vw), 1216 (w), 1127 (vw), 1111 (s), 1094 (vw), 1036 (w), 1000 (w), 977 (m), 953 (w), 895 (w), 831 (w), 796 (m), 781 (m), 730 (m), 653 (m), 629 (w), 567 (w), 475 (w). Anal. Calcd for C13H11CuN2O5 (338.78): C, 46.05; H, 3.25; N, 8.26. Found: C, 46.26; H, 3.32; N, 8.39. X-ray Crystallography. Single crystals of complexes 1
3 were mounted on a glass fiber for X-ray diffraction analysis. Data sets were collected on a Rigaku AFC7R with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) from a rotating anode generator at 293 K. Intensities were corrected for LP factors and empirical absorption by the ψ scan technique. The structures were solved by direct methods and refined on F2 with full-matrix least-squares techniques by use of Siemens SHELXTL version 5 package of crystallographic software.16 All nonhydrogen atoms were refined anistropically. The positions of H atoms were generated geometrically (C
H bond fixed at 0.96 Å), assigned isotropic thermal parameters, and allowed to ride on their parent carbon atoms before the final cycle of refinement. Crystal data as well as details of data collection and refinement for complexes 1
3 are summarized in Table 1. Selected bond distances and bond angles are given in Table 2.

’ RESULTS AND DISCUSSION Synthesis. It is well-known that the key to designing magnetic MOFs is the judicious selection of bridging organic ligands that can mediate magnetic coupling and construct novel structures. V-shaped 1,3-benzenedicarboxylate and its derivatives are promising organic 4518

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Table 2. Selected Bond Lengths and Angles in Complexes 1
3a Ni(1)
N(2)

Complex 1 1.980(2) Ni(1)
O(5)

2.027(2)

Ni(1)
O(4)b

2.010(2)

Ni(1)
O(2)c

2.090(2)

Ni(1)
O(3)d

2.129(2)

Ni(1)
O(3)c

2.326(2)

Ni(1)
Ni(1)b

2.7257(6)

N(2)
Ni(1)
O(5) O(2)c
Ni(1)
O(3)c

95.72(8) 59.49(6)

O(4)b
Ni(1)
O(5) N(2)
Ni(1)
O(2)c

166.62(7) 101.69(8)

N(2)
Ni(1)
O(4)b

95.89(8)

O(4)b
Ni(1)
O(2)c

96.16(7)

c

87.96(7)

O(2)c
Ni(1)
O(3)d

163.89(7)

N(2)
Ni(1)
O(3)d

94.05(8)

N(2)
Ni(1)
O(3)c

161.16(8)

O(4)b
Ni(1)
O(3)d

85.54(7)

O(4)b
Ni(1)
O(3)c

87.55(7)

O(5)
Ni(1)
O(3)d

87.04(7)

O(5)
Ni(1)
O(3)c

83.54(7)

O(3)d
Ni(1)
O(3)c

104.70(6)

Co(1)
O(5)

Complex 2 2.002(2) Co(1)
O(3)e

Co(1)
N(2)

2.023(2)

Co(1)
Co(1)f

2.910(1)

Co(1)
O(4)f

2.024(2)

Co(1)
O(2)e

2.100(2)

Co(1)
O(3)g

2.325(2)

Co(1)
Co(1)f

2.910(1)

O(5)
Co(1)
N(2) O(5)
Co(1)
O(4)f

96.77(9) 160.14(8)

O(2)e
Co(1)
O(3)e N(2)
Co(1)
O(4)f

58.60(7) 96.08(9)

O(5)
Co(1)
O(2)e

100.99(8)

O(4)f
Co(1)
O(3)g

82.62(8)

e

105.10(9)

O(2)e
Co(1)
O(3)g

161.44(7)

O(4)f
Co(1)
O(2)e

90.17(8)

O(5)
Co(1)
O(3)e

88.04(7)

O(5)
Co(1)
O(3)g

81.70(8)

N(2)
Co(1)
O(3)e

163.67(8)

N(2)
Co(1)
O(3)g

92.70(9)

O(4)f
Co(1)
O(3)e

83.82(7)

O(3)g
Co(1)
O(3)e

103.44(6)

O(5)
Ni(1)
O(2)

N(2)
Co(1)
O(2)

2.373(2)

Cu(1)
O(4)h

Complex 3 1.9432(17) Cu(1)
O(5)

1.9666(17)

Cu(1)
N(2)

1.953(2)

Cu(1)
O(2)i

2.4174(18)

Cu(1)
O(3)i

2.0222(17)

Cu(1)
Cu(1)h

2.8158(6)

O(4)
Cu(1)
N(2)

93.94(8)

O(4)h
Cu(1)
O(5)

160.74(7)

N(2)
Cu(1)
O(5) O(4)h
Cu(1)
O(3)i

92.79(8) 93.00(7)

O(4)h
Cu(1)
O(2)i O(5)
Cu(1)
O(2)i

107.84(7) 88.65(7)

N(2)
Cu(1)
O(3)i

158.91(8)

O(3)i
Cu(1)
O(2)i

58.75(6)

87.09(7)

N(2)
Cu(1)
O(2)i

100.16(8)

h

O(5)
Cu(1)
O(3)

i

a

Bond lengths are given in angstroms; bond angles are given in degrees. Symmetry transformations were used to generate equivalent atoms as noted. b Symmetry transformation (
x,
y + 1,
z + 1). c Symmetry transformation (x
1/2,
y + 3/2, z
1/2). d Symmetry transformation (
x + 1/2, y
1/2,
z + 3/2). e Symmetry transformation (
x + 1/2, y + 1/2,
z + 5/2). f Symmetry transformation (
x,
y,
z + 2). g Symmetry transformation (x
1/2,
y
1/2, z
1/2). h Symmetry transformation (
x,
y + 1,
z + 1). i Symmetry transformation (x
1/2,
y + 3/2, z
1/2).

ligands for the construction of the fascinating MOFs.4a,b,8 A variety of discrete 1D, 2D, and 3D MOFs were generated with 1,3benzenedicarboxylates as ligands, and the steric and electronic effects of 5-positioned substituents of the ligands on structures and properties of MOFs were explored.8b,11 In these ligands, we are interested in H2ip-OH. Its two carboxylate groups may coordinate to metal ions, generating charge-neutral network, and its hydroxyl is usually not involved in coordination but can serve as a hydrogenbonding donor to form strong supramolecualr interactions, which results in the further stabilization of MOFs and potential formation of predictable interpenetrating structures.9d,10c,10e On the other

Figure 1. Dinuclear metal unit and perspective view of coordination environments in 1.

Scheme 1. Coordination Modes of ip-OH and Bimb in 1
3

hand, the coordination geometry and radius of metal ions may produce distinct structural topologies, even under the same reaction conditions. Thus, the preferential conformation of flexible ligands is displayed to meet the coordination geometry of metal ions or clusters; this may contribute to an understanding of the assembly and recognition processes.13,14 Interestingly, the hydrothermal reactions of H2ip-OH, Bimb, and MCl2 [M = Ni(II) (1), Co(II) (2), or Cu(II) (3)] produced two-folded interpenetrating 3D coordination polymers, in which Bimb bridges two dinuclear secondary building units (SBUs) in a gauche
antigauche conformation. The SBUs are well separated by ip-OH and Bimb. Description of Crystal Structures. [M(ip-OH)(Bimb)0.5 ]n [M = Ni(II) (1) and Co(II) (2)]. Single-crystal X-ray diffraction analysis revealed that complexes 1 and 2 are isomorphous and crystallize in the monoclinic space group P2(1)/n. They are two-folded interpenetrating 3D coordination networks consisting of dimetal(II)
tetracarboxylate units bridged by ip-OH and Bimb. Herein, we describe only the structure of 1 as an example. As shown in Figure 1, each dinuclear unit in 1 has a crystallographic inversion center at the center of the Ni
Ni(1A) cores. The two Ni(II) are bridged equivalently by two μ2,η2-carboxylates and two μ2-chelating/bridging carboxylates from four different ip-OH, 4519

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Scheme 2. Three Types of Carboxylate-Bridged Dinuclear Metal Units

Figure 3. View of 3D framework in 1.

Figure 2. View of 2D layer of [Ni(ip-OH)]n in 1.

forming an unusual [Ni2(O2C)4] unit (Scheme 2b), To our knowledge, it is unprecedented in the coordination complexes from dicarboxylate ligands, and it is comparable with the analogous paddle-wheel SBUs (Scheme 2a).6 The Ni 3 3 3 Ni distance in the dinuclear unit is 2.7257(6) Å. Each Ni(II) is in a distorted octahedral geometry and is coordinated by five carboxylate oxygen atoms from four ip-OH and one imidazolyl nitrogen atom. The equatorial plane is defined by one nitrogen atom from Bimb, two chelating carboxylate oxygen atoms and one μ-oxygen atom from different μ2-chelating/bridging carboxylate groups. The Ni(II) is approximately coplanar with the mean plane of the four equatorial atoms with a deviation of 0.0424 Å. Two oxygen atoms from different μ2,η2-carboxylate groups occupy the axial positions with the O(4A)
Ni(1)
O(5) bond angle being 166.62(7)°. The axial Ni
O(4A) and Ni
O(5) bond distances are 2.010(2) and 2.027(2) Å, respectively, which are shorter than the equatorial Ni
O bond distances [2.090(2)
2.326(2) Å]. ip-OH serves as a bridge of four Ni(II) through its μ2,η2-carboxylate and μ2-chelating/ bridging carboxylate (Scheme 1a); the two carboxylates are slightly twisted with respect to the central phenyl ring with the dihedral angles between them being 2.6° and 11.4°, respectively. As expected, its hydroxyl is not involved in coordination with metal ions but serves as a hydrogen-bonded donor to form a strong hydrogen bond with one adjacent carboxylate oxygen atom [O(1)
H(1A) 3 3 3 O2i 2.826(3) Å, symmetry code (i) x + 1/2,
y + 3/2, z
1/2]. ip-OH interconnects two SBUs into a 2D layer containing rhombic cavities (Figure 2). Bimb possesses central symmetry and exhibits a gauche
antigauche conformation (Scheme 1c), the plane of N(CH2)4N spacer is steeply inclined

Figure 4. A large cavity in 1, which is further stretched into a two-folded interpenetrating 3D network.

to the plane of the imidazolyl ring by 77.1°. Bimb bridges two adjacent layers to afford a 3D open framework containing large cavities with dimensions of about 8.864  8.864  12.416 Å3 based on the shortest Ni(II) 3 3 3 Ni(II) separation (Figure 3). However, because of the absence of larger guest molecules to fill the large void space in the 3D network, instead of forming an open microporous structure, a two-folded interpenetrating framework is generated (Figure 4). The hydrogen bonds between ip-OH hydroxyl and a carboxylate oxygen atom from the other 3D network further consolidate the architecture. If the dinuclear SBU is considered as a node, it is interconnected with six identical SBUs through four ip-OH and two Bimb to generate a 6-connected α-Po topology (Figures 5 and 6). [Cu(ip-OH)(Bimb)0.5]n (3). Complex 3 also crystallizes in the monoclinic space group P2(1)/n and has a two-folded interpenetrating 3D coordination network consisting of dimetal(II)
tetracarboxylate units bridged by ip-OH and Bimb, but its SBUs are much different from that in 1 and 2 as well as the paddlewheel SBUs (Scheme 2c). As shown in Figure 7, two equivalent Cu(II) are bridged by two μ2,η2-carboxylates from 4520

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Figure 5. Each dinuclear metal center unit can be considered as a node, connected to six others through four ip-OH and two Bimb ligands to generate an extended 3D network.

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Figure 7. Dinuclear metal unit and perspective view of coordination environments in 3.

Figure 8. View of 3D network pillared by Bimb along b axis in 3.

Figure 6. Two-folded interpenetrating α-Po topology in 1.

different ip-OH. The Cu 3 3 3 Cu distance in the SBU is 2.8158(6) Å. Each Cu(II) is in a distorted triagonal bipyramidal geometry and is coordinated by one chelating carboxylate group, two μ2,η2-carboxylate oxygen atoms from different ip-OH, and one imidazolyl nitrogen atom from Bimb, in which two chelating carboxylate oxygen atoms and an imidazolyl nitrogen atom comprise the equatorial plane. Two oxygen atoms from different μ2,η2-carboxylate occupy the axial positions with O(4A)
Cu(1)
O(5) bond angle being 160.74(7)°. ip-OH serves as a bridge of three Cu(II) through its μ2,η2-carboxylate and chelating carboxylate groups (Scheme 1b), which is much different from that in complexes 1 and 2. The twisting angles between two carboxylate and the central phenyl ring in ip-OH are 20.0° and 13.8°, respectively. Consequently, the dinuclear Cu(II) unit is connected by ip-OH to generate a 2D layer. The exo-bidentate Bimb adopts a gauche
antigauche conformation and serves as a flexible pillar through trans-coordination to SBUs of different [Cu(ip-OH)]n layers. It further links 2D layers into a 3D network (Figure 8). The large void in the network and hydrogen bonds between ip-OH hydroxyl and carboxylate oxygen from different

Figure 9. Two-folded interpenetrating framework in 3.

3D networks [O(1)
H(1A) 3 3 3 O2i 2.756(3) Å, symmetry code (i) x + 1/2,
y + 3/2, z
1/2] result in the formation of a twofolded interpenetrating framework (Figure 9), which is similar to that in 1 and 2. 4521

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Figure 10. Temperature dependence of χm
1 and χmT in 1. Solid lines represent the best theoretical fits.

Figure 11. Temperature dependence of χm
1 and χmT in 2. Solid lines represent the best theoretical fits.

Thermogravimetric Analysis. The thermal stabilities of complexes 1
3 were investigated on crystalline samples under nitrogen atmosphere. As shown in Figure S1 in Supporting Information, the thermogravimetric analysis (TGA) curves of complexes 1
3 show that there is no chemical decomposition up to 385, 360, and 275 °C, respectively; subsequent significant weight losses occur after the onset temperature. It is obvious that the thermal stability of 3 is lower than that of 1 and 2. X-ray Powder Diffraction. In order to check the purity of complexes 1
3, the original samples of the three complexes are measured by X-ray powder diffraction (XRPD) at room temperature. As shown in Figures S2
S4 in Supporting Information, the peak positions of experimental patterns are in good agreement with the simulated ones, which clearly indicates the good purity of the complexes. Magnetic Properties of Complexes 1
3. The magnetic susceptibilities of complexes 1
3 were measured in 2
300 K temperature range at an applied field of 1000 Oe. The plots of χm
1 and χmT versus T in 1 are shown in Figure 10. At 300 K, χmT is 1.16 cm3 3 K 3 mol
1 (3.04μB) for Ni(II), which is in agreement with the reported value for Ni(II) complexes in a distorted octahedral coordination geometry.17 χmT decreases smoothly when the temperature is reduced, which is indicative of an antiferromagnetic interaction between the local spin triplet states of the octahedral Ni(II). The χm
1 versus T plot above 25 K obeys the Curie
Weiss law, χm = C/(T
θ), with a Weiss constant θ =
22.46 K and a Curie constant C = 1.26 cm3 3 K 3 mol
1. The negative θ further confirms antiferromagnetic coupling. In complex 1, the Ni(II) 3 3 3 Ni(II) distance in the dinuclear unit is 2.7256(6) Å; the nearest Ni(II) 3 3 3 Ni(II) separations between the adjacent SBUs bridged by ip-OH and Bimb are 8.864 and 12.416 Å, respectively; and the nearest Ni(II) 3 3 3 Ni(II) separation between the adjacent interpenetrating 3D networks is 6.290 Å. This shows that the efficient magnetic superexchange pathway mainly results from the dinuclear metal units, which confirms that SBUs in 1 are well isolated by ip-OH and Bimb. Thus, the magnetic data were analyzed through the expression for a dinuclear Ni(II) system (S1 = S2 = 1) derived from the isotropic spin Hamiltonian H =
J∑S1S2 with the influence of collaboration of zero-field splitting and the interaction between adjacent dinuclear units not considered. This model turned out to be satisfactory in this case, and we obtained the best-fit parameters J/k =
21.87 ( 0.06 and g = 2.22 ( 0.00 cm
1 and the agreement factor R = 4  10
5, where

R = [(χm)obsd
(χm)calcd]2/ [(χm)obsd]2 . The negative J values are consistent with the occurrence of antiferromagnetic coupling between the Ni(II) ions. The plots of χm
1 and χmT versus T in complex 2 are shown in Figure 11. The χmT value at 298 K of 3.42 cm3 3 K 3 mol
1 (5.23 μB) is significantly greater than the spin-only value (3.87μB; μso = [4S(S + 1)]1/2; S = 3/2) for a high-spin Co(II) center, while it agrees with the values [5.20μB; μls = [L(L + 1) + 4S(S + 1)]1/2; L = 3, S = 3/2] observed for high-spin Co(II) complexes in an octahedral surrounding with a significant firstorder orbital contribution to the magnetic moment.18 The value of χmT decreases smoothly until ∼100 K and then goes down quickly to a minimum value of 0.75 cm3 3 K 3 mol
1 at 2 K, probably due to an overall antiferromagnetic coupling or the contribution of orbital momentum in complex 2. The temperature dependence of magnetic susceptibilities above 2 K follows the Curie
Weiss law, χm = C/(T
θ), with a Weiss constant θ =
15.30 K and a Curie constant C = 3.48 cm3 3 K 3 mol
1. The Co(II) 3 3 3 Co(II) distance in the dinuclear SBU is 2.9102(8) Å, and the smallest Co(II) 3 3 3 Co(II) separations between the adjacent SBUs bridged by ip-OH and Bimb as well as between the adjacent interpenetrating 3D networks are 8.833, 12.464, and 6.141 Å, respectively. Therefore, the efficient magnetic superexchange pathway is mainly inside the dinuclear unit. The data are fitted to a Lines’ model by use of MagSaki(A) Software.19 The best fit of the data gives J =
1.01 cm
1, λ =
98 cm
1, orbitalreduction factor k = 0.84, axial splitting parameter Δ = 345.7 cm
1, temperature-independent paramagnetism TIP = 1.8  10
3 cm3 3 mol
1, and agreement factor R = 2.2  10
3. The fitting result of a small negative value for J indicates that complex 2 has very weak antiferromagnetic interaction between the nearest Co(II) ions. The fitting result is comparable with those reported for other coupled Co(II) dimers.20 As shown in Figure 12, the value of χmT at 300 K in complex 3 is 0.35 cm3 3 K 3 mol
1 (μeff = 1.67μB), which is lower than the expected spin-only value of 0.375 cm3 3 K 3 mol
1 (μeff = 1.73μB) for a CuII ion (S = 1/2 and g = 2.0), indicating that 3 is antiferromagnetically coupled. Above 60 K, the plot of χm
1 versus T obeys the Curie
Weiss law, χm = C/(T
θ), with a Curie constant C = 0.41 cm3 3 K 3 mol
1 and a Weiss constant θ =
39.38 K, which also implies that the magnetic exchange in 3 is antiferromagnetic. The Cu(II) 3 3 3 Cu(II) distance in the dinuclear SBU is 2.8158(6) Å, and the smallest intercluster Cu(II) 3 3 3 Cu(II) separations bridged by ip-OH and Bimb are 4522

dx.doi.org/10.1021/cg200730k |Cryst. Growth Des. 2011, 11, 4517–4524

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ARTICLE

’ AUTHOR INFORMATION Corresponding Author

*E-mail [email protected] (X.L.) or [email protected] (S.L.).

Figure 12. Temperature dependence of χm
1 and χmT in 3. Solid lines represent the best theoretical fits.

8.967 and 12.542 Å, respectively, which are shorter than that in 1 and 2, while the smallest intercluster between the adjacent interpenetrating 3D networks of 5.914 Å is longer than that in 1 and 2. The susceptibility data are fitted by use of the Bleaney
Bowers dimer equation,21 and neglecting the interaction between adjacent dinuclear units. This model turned out to be in agreement with this case, and a fitting obtained by above equation gave J/k =
37.88 ( 0.32 cm
1, g = 2.03 ( 0.01, and R = Σ[(χcalcd
χexptl)/χexptl]2 = 4.05  10
5. The negative value of J/k suggests antiferromagnetic coupling in 3.

’ CONCLUSIONS Three two-folded interpenetrating 3D MOFs based on binuclear SBUs have been synthesized from rigid dicarboxylate (ip-OH) and flexible bis(imidazolyl) (Bimb) ligands. ip-OH links SBUs into a 2D charge-neutral layer, which is further extended into a 3D network through Bimb trans-coordinating to SBUs of the adjacent layers. The hydrogen bonds between hydroxyl and carboxylate oxygen atom of different ip-OH contribute to the formation of two-folded interpenetrating structures and the further stabilization of MOFs. Bimb exhibits a gauche
antigauche conformation to meet the requirement of SBU coordination geometry. Interestingly, the Ni(II) and Co(II) dimetal(II)
tetracarboxylate SBUs in 1 and 2 are unprecedented in coordination complexes from dicarboxylate ligands, while dicopper(II)
tetracarboxylate SBU in 3 is much different from that in 1 and 2, owing to the difference in coordination geometry of metal ions, resulting in lower thermal stability. The SBUs in 1
3 are well separated by ip-OH and Bimb, which simplifies the magnetic exchange of metal ions and the magnetic prediction of final complexes. In summary, this research demonstrates that magnetic MOFs based on dinuclear units can be constructed from rigid dicarboxylate ligands and flexible bis(imidazolyl) ligands, this may widen the approach toward the design and synthesis of novel MOFs and magnetic materials. ’ ASSOCIATED CONTENT

bS

Supporting Information. X-ray crystallographic files (CIF); four figures showing TGA curves and experimental and simulated X-ray powder diffraction patterns for complexes 1
3 (PDF). This material is available free of charge via the Internet at http://pubs.acs.org. Crystallographic data for 1
3 have been deposited in the Cambridge Crystallographic Data Centre with CCDC numbers 798092, 798093, and 798094.

’ ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (21001025), the Natural Science Foundation of Fujian Province (2010J05017, 2008I0013), State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences (20100016), and Extra-curricular Science and Technology Project of Fujian Normal University (BKL2010-035). ’ REFERENCES (1) (a) Kahn, O. Adv. Inorg. Chem. 1995, 43, 179. (b) Gutschke, S. O. H.; Price, D. J.; Powell, A. K.; Wood, P. T. Angew. Chem., Int. Ed. 1999, 38, 1088. (c) Gao, E. Q.; Bai, S. Q.; Wang, Z. M.; Yan, C. H. J. Am. Chem. Soc. 2003, 125, 4984. (d) Cheng, X. N.; Zhang, W. X.; Chen, X. M. J. Am. Chem. Soc. 2007, 129, 15738. (e) Wang, X. Y.; Wang, Z. M.; Gao, S. Chem. Commun. 2008, 281. (2) (a) Albores, P.; Rentschler, E. Dalton Trans. 2009, 2609. (b) Mondal, K. C.; Kostakis, G. E.; Lan, Y. H.; Anson, C. E.; Powell, A. K. Inorg. Chem. 2009, 48, 9205. (c) Jia, H. P.; Li, W.; Ju, Z. F.; Zhang, J. Chem. Commun. 2008, 371. (d) Li, J. R.; Yu, Q.; Tao, Y.; Bu, X. H.; Ribas, J.; Batten, S. R. Chem. Commun. 2007, 2290. (e) Escuer, A.; Aromi, G. Eur. J. Inorg. Chem. 2006, 4721. (3) (a) Hao, X.; Wei, Y.; Zhang, S. Chem. Commun. 2000, 2271. (b) Okada, K.; Nagao, O.; Mori, H.; Kozaki, M.; Shiomi, D.; Sato, K.; Takui, T.; Kitagawa, Y.; Yamaguchi, K. Inorg. Chem. 2003, 42, 3221. (c) Wang, R.; Gao, E.; Hong, M.; Gao, S.; Luo, J.; Lin, Z.; Han, L.; Cao, R. Inorg. Chem. 2003, 42, 5486. (d) Ma, Y.; Cheng, A. L.; Gao, E. Q. Cryst. Growth Des. 2010, 10, 2832. (e) Cheng, A. L.; Ma, Y.; Gao, E. Q. CrystEngComm 2011, 13, 2721. (4) (a) Nouar, F.; Eubank, J. F.; Bousquet, T.; Wojtas, L.; Zaworotko, M. J.; Eddaoudi, M. J. Am. Chem. Soc. 2008, 130, 1833. (b) Furukawa, H.; Kim, J.; Ockwig, N. W.; O’Keeffe, M.; Yaghi, O. M. J. Am. Chem. Soc. 2008, 130, 11650. (c) Li, Z. G.; Wang, G. H.; Jia, H. Q.; Hu, N. H.; Xu, J. W.; Batten, S. R. CrystEngComm 2008, 10, 983. (d) Konar, S.; Mukherjee, P. S.; Zangrando, E.; Lloret, F.; Chaudhuri, N. R. Angew. Chem., Int. Ed. 2002, 41, 1561. (e) Gutschke, S. O. H.; Price, D. J.; Powell, A. K.; Wood, P. T. Eur. J. Inorg. Chem. 2001, 2739. (5) (a) Fabelo, O.; Pasan, J.; Lloret, F.; Julve, M.; Ruiz-Perez, C. Inorg. Chem. 2008, 47, 3568. (b) Suarez-Varela, J.; Sakiyama, H.; Cano, J.; Colacio, E. Dalton Trans. 2007, 249. (c) Rueff, J. M.; Pillet, S.; Claiser, N.; Bonaventure, G.; Souhassou, M.; Rabu, P. Eur. J. Inorg. Chem. 2002, 895. (d) Livage, C.; Egger, C.; Ferey, G. Chem. Mater. 1999, 11, 1546. (e) DeMunno, G.; Poerio, T.; Julve, M.; Lloret, F.; Viau, G. New J. Chem. 1998, 22, 299. (6) (a) Mereacre, V. M.; Ako, A. M.; Clerac, R.; Wernsdorfer, W.; Filoti, G.; Bartolome, J.; Anson, C. E.; Powell, A. K. J. Am. Chem. Soc. 2007, 129, 9248. (b) Mishra, A.; Tasiopoulos, A. J.; Wernsdorfer, W.; Moushi, E. E.; Moulton, B.; Zaworotko, M. J.; Abboud, K. A.; Christou, G. Inorg. Chem. 2008, 47, 4832. (c) Mereacre, V.; Ako, A. M.; Clerac, R.; Wernsdorfer, W.; Hewitt, I. J.; Anson, C. E.; Powell, A. K. Chem.—Eur. J. 2008, 14, 3577. (7) (a) Kitaura, R.; Seki, K.; Akiyama, G.; Kitagawa, S. Angew. Chem., Int. Ed. 2003, 42, 428. (b) Rather, B.; Zaworotko, M. J. Chem. Commun. 2003, 830. (c) Chun, H.; Dybtsev, D. N.; Kim, H.; Kim, K. Chem.—Eur. J. 2005, 11, 3521. (d) Ma, B. Q.; Mulfort, K. L.; Hupp, J. T. Inorg. Chem. 2005, 44, 4912. (e) Cho, S. H.; Ma, B. Q.; Nguyen, S. T.; Hupp, J. T.; Albrecht-Schmitt, T. E. Chem. Commun. 2006, 2563. (8) (a) García-Couceiro, U.; Castillo, O.; Cepeda, J.; Lanchas, M.; Luque, A.; Perez-Ya nez, S.; Roman, P.; Vallejo-Sanchez, D. Inorg. Chem. 2010, 49, 11346. (b) Yue, Q.; Yan, L.; Zhang, J. Y.; Gao, E. Q. Inorg. 4523

dx.doi.org/10.1021/cg200730k |Cryst. Growth Des. 2011, 11, 4517–4524

Crystal Growth & Design

ARTICLE

Chem. 2010, 49, 8647. (c) Yue, Q.; Sun, Q.; Cheng, A. L.; Gao, E. Q. Cryst. Growth Des. 2010, 10, 44. (d) Ma, L. F.; Wang, L. Y.; Wang, Y. Y.; Batten, S. R.; Wang, J. G. Inorg. Chem. 2009, 48, 915. (e) Zeng, M. H.; Hu, S.; Chen, Q.; Xie, G.; Shuai, Q.; Gao, S. L.; Tang, L. Y. Inorg. Chem. 2009, 48, 7070. (9) (a) Tian, H.; Jia, Q. X.; Gao, E. Q.; Wang, Q. L. Chem. Commun. 2010, 5349. (b) Zhuang, W. J.; Sun, H. L.; Xu, H. B.; Wang, Z. M.; Gao, S.; Jin, L. P. Chem. Commun. 2010, 4339. (c) Ma, Q.; Zhu, M. L.; Lu, L. P.; Feng, S. S.; Wang, T. W. Dalton Trans. 2010, 5877. (d) Feller, R. K.; Cheetham, A. K. Dalton Trans. 2008, 2034. (e) Rao, C. N. R.; Natarajan, S.; Vaidhyanathan, R. Angew. Chem., Int. Ed. 2004, 43, 1466. (f) Wang, R. H.; Hong, M. C.; Luo, J. H.; Cao, R.; Weng, J. B. Chem. Commun. 2003, 1018. (10) (a) Li, X. J.; Weng, X. L.; Tang, R. J.; Lin, Y. M.; Ke, Z. L.; Zhou, W. B.; Cao, R. Cryst. Growth Des. 2010, 10, 3228. (b) Li, X. J.; Cao, R.; Guo, Z. G.; Li, Y. F.; Zhu, X. D. Polyhedron 2007, 26, 3911. (c) Li, X. J.; Wang, X. Y.; Gao, S.; Cao, R. Inorg. Chem. 2006, 45, 1508. (d) Li, X. J.; Cao, R.; Guo, Z. G.; Bi, W. H.; Yuan, D. Q. Inorg. Chem. Commun. 2006, 9551. (e) Li, X. J.; Cao, R.; Sun, D. F.; Bi, W. H.; Wang, Y. Q.; Li, X.; Hong, M. C. Cryst. Growth Des. 2004, 4, 775. (11) Li, X. J.; Cao, R.; Bi, W. H.; Wang, Y. Q.; Wang, Y. L.; Li, X.; Guo, Z. G. Cryst. Growth Des. 2005, 5, 1651. (12) (a) Fukushima, T.; Horike, S.; Inubushi, Y.; Nakagawa, K.; Kubota, Y.; Takata, M.; Kitagawa, S. Angew. Chem., Int. Ed. 2010, 49, 4820. (b) He, H.; Dai, F.; Xie, A.; Tong, X.; Sun, D. CrystEngComm 2008, 10, 1429. (c) Mukhopadhyay, S.; Chatterjee, P. B.; Mandal, D.; Mostafa, G.; Caneschi, A.; Slageren, J.; Weakley, T. J. R.; Chaudhury, M. Inorg. Chem. 2004, 43, 3413. (13) (a) He, H.; Collins, D.; Dai, F.; Zhao, X.; Zhang, G.; Ma, H.; Sun, D. Cryst. Growth Des. 2010, 10, 895. (b) Liu, G. X; Huang, Y. Q.; Chu, Q.; Okamura, T.; Sun, W. Y.; Liang, H.; Ueyama, N. Cryst. Growth Des. 2008, 8, 3233. (c) Wang, R. H.; Zhou, Y. F.; Sun, Y. Q.; Yuan, D. Q.; Han, L.; Lou, B. Y.; Wu, B. L.; Hong, M. C. Cryst. Growth Des. 2005, 5, 251. (d) Dey, S. K.; Bag, B.; Abdul-Malik, K. M.; Salah-El-Fallah, M.; Ribas, J.; Mitra, S. Inorg. Chem. 2003, 42, 4029. (14) (a) Chen, P. K.; Batten, S. R.; Qi, Y.; Zheng, J. M. Cryst. Growth Des. 2009, 9, 2756. (b) Qi, Y.; Luo, F.; Batten, S. R.; Che, Y. X.; Zheng, J. M. Cryst. Growth Des. 2008, 8, 2806. (c) Jin, S. W.; Wang, D. Q.; Chen, W. Z. Inorg. Chem. Commun. 2007, 10, 685. (d) Ma, L. F.; Meng, Q. L.; Wang, L. Y.; Liang, F. P. Inorg. Chim. Acta 2010, 363, 4127. (e) Cui, G. H.; Li, J. R.; Tian, J. L.; Bu, X. H.; Batten, S. R. Cryst. Growth Des. 2005, 5, 1775. (f) Ma, J. F.; Yang, J.; Zheng, G. L.; Li, L.; Liu, J. F. Inorg. Chem. 2003, 42, 7531. (15) Bentiss, F.; Lagrenee, M. J. Heterocycl. Chem. 1999, 36, 1029. (16) SHELXTL Version 5 Reference Manual; Science Energy & Automation Inc.: Madison, WI, 1994. (17) (a) Ginsberg, A. P.; Martin, R. L.; Brookes, R. W.; Sherwood, R. C. Inorg. Chem. 1972, 11, 2884. (b) Roth, A.; Buchhoz, A.; Rudolph, M.; Schuetze, E.; Kothe, E.; Plass, W. Chem.—Eur. J. 2008, 14, 1571. (18) (a) Lu, J. Y.; Lawandy, M. A.; Li, J.; Yuen, T.; Lin, C. L. Inorg. Chem. 1999, 38, 2695. (b) Zheng, L. M.; Fang, X.; Li, K. H.; Song, H. H.; Xin, X. Q.; Fun, H. K.; Chinnakali, K.; Razak, I. A. Dalton Trans. 1999, 2311. (c) Garcia-Couceiro, U.; Castillo, O.; Luque, A.; Beobide, G.; Roman, P. Inorg. Chim. Acta 2004, 357, 339. (19) (a) Lines, M. E. J. Chem. Phys. 1971, 55, 2977. (b) Munno, G. D.; Julve, M.; Lloret, F.; Fausb, J.; Caneschi, A. J. Chem. Soc., Dalton Trans. 1994, 1175. (c) Lin, S. Y.; Xu, G. F.; Zhao, L.; Tang, J. K.; Liu, G. X. Z. Anorg. Allg. Chem. 2011, 637, 720. (d) Sakiyama, H. J. Chem. Software 2001, 7, 171. (20) (a) Sakiyama, H.; Ito, R.; Kumagai, H.; Inoue, K.; Sakamoto, M.; Nishida, Y.; Yamasaki, M. Eur. J. Inorg. Chem. 2001, 2705. (b) Hossain, M. J.; Yamasaki, M.; Mikuriya, M.; Kuribayashi, A.; Sakiyama, H. Inorg. Chem. 2002, 41, 4058. (21) Bleaney, B.; Bowers, K. D. Proc. R. Soc. London, Ser. A 1952, 214, 451.

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