Construction of MetalâOrganic Frameworks Based on Two Neutral

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Construction of Metal–Organic Frameworks Based on Two Neutral Tetradentate Ligands Ling Qin, Jinsong Hu, Mingdao Zhang, Yizhi Li, and Hegen Zheng Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/cg300803n • Publication Date (Web): 22 Aug 2012 Downloaded from http://pubs.acs.org on August 23, 2012

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Crystal Growth & Design

Construction of Metal–Organic Frameworks Based on Two Neutral Tetradentate Ligands

Ling Qin, Jinsong Hu, Mingdao Zhang, Yizhi Li, and Hegen Zheng∗

State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.

ABSTRACT: The solvothermal reaction of two new neutral tetradentate ligands with different bivalent metal salts gave seven metal-organic frameworks (MOFs): [Co2(L1) (trans-chdc)2]·5H2O (1), [Zn2(L1)(trans-chdc)(NO2)2]·DMF (2), [Cd2(L1)(transchdc)2]·4H2O

(3),

[Zn2(L1)(1,4-bdc)2]·(H2O)3

(4),

[Cd2(L1)(1,4-

bdc)2]·DMF·(Solvent)x (5), [Co(L2) (trans-chdc)(H2O)]·1.5H2O (6), [Co(L2) (1,4-bdc) (H2O)] · 2H2O (7), (L1 = 1,1'-oxybis[3,5-diimidazole]-benzene, L2 = 1,1'-oxybis[3,5dipyridine]-benzene, trans-chdc = trans-1,4-cyclohexanedicarboxylic acid, 1,4-bdc = 1,4-benzenedicarboxylate). These MOFs were prepared to examine the effects of the core metal ion, or organic ligand on the topology and interpenetration form. The results show that imidazole ligand can rotate easily to coordinate to metal ions, while pyridine ligand exhibits the weaker coordinative abilities, which may influence the self-assembly. Compounds 1, 3, and 5 are three-dimensional (3D) frameworks with 2fold interpenetrated forms, whereas complex 4 shows 3-fold interpenetrated structures. Interestingly, compound 2 exhibits a 4-fold interpenetration. Compound 6 features a 2D polymeric layer structure which exhibits a rare 2-fold interpenetrating 3D hms array if H-bonds are taken into account. For compound 7, the dinuclear cobalt secondary building unit (SBU) assembles with mixed-ligands, L2 and 1,4-bdc, to

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construst a 3D α-Po structure.

Introduction The design and synthesis of solid-state compounds known as metal-organic frameworks (MOFs) is at the forefront of modern materials chemistry. In the past decade, these matierials have garnered an interesting field of chemistry for their intriguing structures and potential applications in catalysis, and optical, magnetic, solvatochromic, and porous materials. 1Interpenetration has long been considered a major impediment in the achievement of stable and porous crystalline structures. While, recent report shows that the existence of interpenetration is not necessarily negative, interpenetrating MOFs, as potential candidates for functional materials,

2

have attracted considerable interest. Yaghi and co-workers have gave some detail discussions on the relationship between porosity and interpenetration of open frameworks.2e They gave a plot of n (degree of interpenetration) as a function of d (diameter of the SBUs) and l (length of linkers) and their relationship to the free volume. The rapid growth in this area provides a large number of interpenetrating architectures with interesting topology and various degrees of interpenetration, which is helpful to interpret the law of self-assembly. 3 It is undoubted that a mixed-ligand is a good choice for the construction of new frameworks. However, it is accompanied with even more uncertain elements. Thus the prediction of mixed-ligand architectures is a challenging scientific endeavour.4 Besides, syntheses of new nitrogen-containing ligands are long-standing fascination of chemists, and so far, a great number of bidentate or tridentate nitrogen-containing ligands have been reported, but the study of polydentate nitrogen-containing ligands is still less developed.5 Unlike bipyridine ligands, which tend to function as spacers


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between framework nodes and thus play little or no roles in the framework topological type, tetradentate ligands can serve as 4-connected nodes, leading to novel 4-connected topologies.

Scheme 1. Two neutral tetradentate N-containing ligands and carboxylate co-ligands

To test the use of the larger size ligands to give new architectures, we designed and synthesized two tetradentate ligands to get seven MOFs, that is [Co2(L1) (transchdc)2]·5H2O chdc)2]·4H2O

(1), (3),

[Zn2(L1)(trans-chdc)(NO2)2]·DMF [Zn2(L1)(1,4-bdc)2]·(H2O)3

(2),

[Cd2(L1)(trans-

(4),

[Cd2(L1)(1,4-

bdc)2]·DMF·(Solvent)x (5), [Co(L2) (trans-chdc)(H2O)]·1.5H2O (6), [Co(L2) (1,4bdc) (H2O)] · 2H2O (7). Different carboxylate co-ligands were carefully and purposefully selected to adjust the connectivity and final crystal structure.

Experimental Section Materials and Methods. All chemicals and solvents used in the syntheses were of reagent grade and were used without further purification. trans-chdc, and 1,4-bdc were used as commercially available. L1 and L2 ligands were prepared on the basis



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of Ullman reaction and palladium-catalyzed cross-coupling reactions, respectively.6 The IR absorption spectra of these complexes were recorded in the range of 400 – 4000 cm-1 by means of a Nicolet (Impact 410) spectrometer with KBr pellets. C, H and N elemental analyses were carried out with a Perkin Elmer 240C elemental analyzer. Powder X-ray diffraction (PXRD) measurements were performed on a Bruker D8 Advance X-ray diffractometer using Cu-Kα radiation (1.5418 Å), and the X-ray tube was operated at 40 kV and 40 mA. Thermogravimetric analysis (TGA) was performed on a Perkin Elmer thermogravimetric analyzer Pyris 1 TGA from 298 K up to 1023 K with a heating rate of 20 K⋅min-1 under N2 atmosphere. Solid-state UV-vis diffuse reflectance spectra was obtained at room temperature using Shimadzu UV-3600 double monochromator spectrophotometer, and BaSO4 was used as a 100% reflectance standard for all materials. Luminescent spectra were recorded with a SHIMAZU VF-320 X-ray fluorescence spectrophotometer at room temperature.

Syntheses of the compounds Synthesis of complex [Co2(L1) (trans-chdc)2]·5H2O (1): A mixture DMF/H2O containing the L1 (43.4 mg, 1 mmol), trans-chdc (34.4 mg, 2 mmol) and Co(NO3)2·6H2O (58.2 mg, 2 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The large quantities of pink-block crystals were obtained and crystals were filtered off, washed with quantities of distilled water, and dried under ambient conditions. Yield of the reaction was ca. 70 % based on L1 ligand. Elemental analysis calcd. for Co2C40H48N8O14 (1): C, 48.89; H, 4.92; N, 11.40, Found: C, 48.94; H, 4.92; N, 11.58. The IR spectrum of the 1 is shown in the Supporting Information (Figure S1). Synthesis of complex [Zn2(L1)(trans-chdc)(NO2)2]·DMF (2): A mixture


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DMF/H2O containing the L1 (43.4 mg, 1 mmol), trans-chdc (17.2 mg, 1 mmol) and Zn(NO3)2·6H2O (59.4 mg, 2 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The large quantities of colourless - prismatic crystals were obtained and crystals were filtered off, washed with quantities of distilled water, and dried under ambient conditions. Yield of the reaction was ca. 55 % based on L1 ligand. Elemental analysis calcd. for Zn2C35H38N11O12 (2): C, 44.93; H, 4.09; N, 16.47, Found: C, 44.91; H, 4.17; N, 16.37. The IR spectrum of the 2 is shown in the Supporting Information (Figure S2). Synthesis of complex [Cd2(L1)(trans-chdc)2]·4H2O (3): A mixture DMF/H2O containing the L1 (43.4 mg, 1 mmol), trans-chdc (34.4 mg, 2 mmol) and Cd(NO3)2·6H2O (60.2 mg, 2 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The large quantities of colourless-block crystals were obtained and crystals were filtered off, washed with quantities of distilled water, and dried under ambient conditions. Yield of the reaction was ca. 78 % based on L1 ligand. Elemental analysis calcd. for Cd2C40H46N8O13 (3): C, 44.83; H, 4.33; N, 10.46, Found: C, 44.94; H, 4.43; N, 10.66. The IR spectrum of the 3 is shown in the Supporting Information (Figure S3). Synthesis of complex [Zn2(L1)(1,4-bdc)2]·(H2O)3 (4): A mixture DMF/H2O containing the L1 (43.4 mg, 1 mmol), 1,4-bdc (33.2 mg, 2 mmol) and Zn(NO3)2·6H2O (59.4 mg, 2 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The large quantities of colourless-block crystals were obtained and crystals were filtered off, washed with quantities of DMF and distilled water, and dried under ambient conditions. Yield of the reaction was ca. 54 % based on L1 ligand. Elemental analysis calcd. for



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Zn2C40H26N8O9 (4): C, 50.71; H, 3.40; N, 11.83, Found: C, 50.73; H, 3.38; N, 11.80. The IR spectrum of 4 is shown in the Supporting Information (Figure S4). Synthesis of complex [Cd2(L1)(1,4-bdc)2]·DMF·(Solvent)x (5): A mixture DMF/H2O containing the L1 (43.4 mg, 1 mmol), 1,4-bdc (33.2 mg, 2 mmol) and Cd(NO3)2·6H2O

(60.2 mg, 2 mmol) were mixed in a Teflon vessel within the

autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. A few of colourless-block crystals were obtained. Synthesis of complex [Co(L2) (trans-chdc)(H2O)]·1.5H2O (6): A mixture DMF/H2O containing the L2 (47.8 mg, 1 mmol), Co(NO3)2·6H2O (29.1 mg, 1 mmol) and trans-chdc (17.2 mg, 1 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The crystals were obtained. The large quantities of purple-block crystals were obtained and crystals were filtered off, washed with quantities of distilled water, and dried under ambient conditions. Yield of the reaction was ca. 55% based on L2 ligand. Elemental analysis calcd. for Co2C80H74N8O15 (6): C, 63.83; H, 4.95; N, 7.44, Found: C, 63.79; H, 5.01; N, 7.48. The IR spectrum of 6 is shown in the Supporting Information (Figure S5). Synthesis of complex [Co(L2) (1,4-bdc) (H2O)] · 2H2O (7): A mixture DMF/H2O containing the L2 (47.8 mg, 1 mmol), Co(NO3)2·6H2O (29.1 mg, 1 mmol) and 1,4-bdc (16.6 mg, 1 mmol) were mixed in a Teflon vessel within the autoclave. The vessel was heated at 95 °C for 72 h and then cooled to room temperature. The crystals were obtained. The large quantities of purple-block crystals were obtained and crystals were filtered off, washed with quantities of distilled water, and dried under ambient conditions. Yield of the reaction was ca. 67% based on L2 ligand. Elemental analysis calcd. for CoC40H32N4O8 (7): C, 63.58; H, 4.27; N, 7.41, Found: C, 63.61; H, 4.23; N, 7.45. The IR spectrum of 7 is shown in the Supporting Information (Figure S6).


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X-ray Crystallography. Crystallographic data of 1-7 were collected on a Bruker Apex Smart CCD diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) using the ω-scan technique. The intensity data were integrated by using the SAINT program.7 An empirical absorption correction was applied using the SADABS program.8 The structures were solved by direct method and the nonhydrogen atoms were located from the trial structures and then refined anisotropically with SHELXTL using full-matrix least-squares procedures based on F2 values. The positions of the non-hydrogen atoms were refined with anisotropic displacement factors. The hydrogen atoms were positioned geometrically by using a riding model. The distribution of peaks in the channels of 4 and 5 were chemically featureless to refine using conventional discrete-atom models. To resolve these issues, the contribution of the electron density by the remaining water molecule was removed by the SQUEEZE routine in PLATON. The crystallographic data for 1-7 are summarized in Table 2 CCDC 861390 – 861394 for 1 – 5, 865913 – 865914 for 6 – 7. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

Results and Discussion Crystal Structures of [Co2(L1)(trans-chdc)2]·5H2O (1) and [Cd2(L1)(transchdc)2]·4H2O (3). Crystal engineering based on predesigned organic linkers and metal centers with specific coordination geometries is an important approach in the preparation of coordination materials.

9

Based on these previous reports, we give

some research. Firstly, the combination of L1, trans-chdc with Co(NO3)2·6H2O or Cd(NO3)2·6H2O led to the formation of similar structures, 1 and 3, respectively. The space groups are P2/c for 1 and P2/n for 3 (different directions of slip plane), respectively (Figure 1a and Figure 1b). The imidazole groups of L1 ligand link four



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Co ions to form an undulating 2D layered network (Figure 1c), and the layer links another 2D sheet via the trans-chdc ligand to generate a 3D framework. A better insight into the nature of this intricate framework is provided by a TOPOS analysis software,10 reducing multidimensional structures to simple nodes and connection nets. The metal cations and the L1 ligands can be regarded as a 4-connected node. Therefore, the whole structure can thus be represented as a 4-c net qtz topology (with the Schläfli symbol {64.82}). The framework 1 occupies 85.4 % of the total crystal volume caculated by Platon;

11

the remaining space is occupied by the water

molecules. The potential voids are large enough to be filled via mutual interpenetration of an independent equivalent framework, generating a 2-fold interpenetrating architecture (Figure 2). Further analysis of interpenetration, according to a recent classification,12 reveals that it belongs to Class IIa.

(a)

(b)

(c)


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Figure 1. (a) X-ray structure of 1 (hydrogen atoms and solvated water molecules are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = -x, y, 1/2 + z; #2 = 2 - x, y, 3/2 - z; #3 = 1 - x, -1 + y, 3/2 - z; #4 = 1 + x, -1 + y, z. (b) Coordination environment of the Cd (II) ions in 3 (hydrogen atoms and uncoordinated water molecules are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = 1/2 - x, -1 + y, 1/2 - z; #2 = 1 + x, -1 + y, z; #3 = 5/2 - x, y, 1/2 - z; #4 = 3/2 - x, y, 3/2 z. (c) A view of the 2D sheet by L1 ligands and Co(II) ions.

Figure 2. Schematic view of two interpenetrating framework with qtz topology.

Crystal Structure of [Zn2(L1) (trans-chdc)(NO2)2]·DMF (2). Note that the Zn (II) and Co (II) MOFs are generally isostructural in the previous reports.13 It was



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expected that, when using the Zn(NO3)2·6H2O or Co(NO3)2·6H2O, the similar structure would be accessible. However, compound 2 crystallizes in a monoclinic form with a space group C2/c and exhibits a fascinating 3D polymeric architecture consisting of four equivalent interpenetrating net with dmd topology. Unlike compounds 1 and 3, one coordinated trans-chdc of 1 or 3 is replaced by coordinated nitrate anion in 2

14

(Figure 3a). The imidazole groups of L1 ligand link four Zn ions

to form chains (Figure 3b), and then the chains form a 3D framework via the transchdc ligands. The potential guest accessible area, in compound 2, is about 19.1% of unit cell volume and the channels are occupied by DMF molecules. According to Blatov's classification, the interpenetration can be classified as type Class Ib, Z = 4[2*2] (Zt=4(2*2); Zn=1) (the two identical interpenetrated nets are generated by translations and the translating vectors are [1/2,1/2,0] (11.76A), [1/2,-1/2,0] (11.76 Å), [0,0,1] (14.86 Å)). Similarly, every Zn2+ ion and L1 ligands can be considered as three and four connected nodes, respectively. Furthermore, they link each other to form a {4.102}2{42.104} dmd net (Figure 3c).

(a)

(b)


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(c)

Figure 3. (a) Coordination environment of the Zn (II) ions in 2. (hydrogen atoms are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = x - 1/2, 1/2 - y, z – 1/2. (b) Views of the 1D chain by L1 ligands and Zn ions. (c) Schematic view of four interpenetrating framework with dmd topology.

Crystal Structures of [Zn2(L1)(1,4-bdc)2]·(H2O)3 (4) and [Cd2(L1)(1,4bdc)2]·DMF·(Solvent)x (5). Although the co-ligand was different, complex 5 is isostructural to 3 (The space group, cell parameters, and topology are identical to those of 3). Such isostructurality between these two different ligands is also present in the other 3D structures.15 Due to the poor reproducibility of 5, the character and property are not described in detail. Complex 4 crystallizes in a triclinic system with a 1

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space group P . As shown in Figure 4a, the framework of 4 consists of two different Zn2+ ions, one L1 ligand together with two 1,4-bdc2- anions. Zn1 cation is fivecoordinated while Zn2 cation is four-coordinated. Zn1 is coordinated by three carboxylate oxygen atoms from two different 1,4-bdc ligands, two N atoms from two L1 ligands, the τ trigonality factor is 0.068, showing a distorted square pyramidal coordination geometry 16. Zn2 is tetrahedrally coordinated by two carboxylate oxygen atoms from two different 1, 4-bdc ligands, two N atoms from L1 ligands. The L1 ligand link four Zn ions to form a 1D ladder-chain (Figure 4b), and the 1, 4-bdc



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ligands link the 1D chain with different propagating direction to form a 3D framework. The desolvated framework shows 24.3% void space to the total crystal volume, as calculated by PLATON. The channels are occupied by water molecules. The potential voids are large enough to be filled via mutual interpenetration of two independent equivalent frameworks, generating a 3-fold interpenetrating 3D architecture (Figure 4c). The interpenetration can be classified as type Class Ia, Z = 3 (Zt=3; Zn=1) (the identical interpenetrated nets are generated by translation and the translating vector is [1,0,0] (9.13 Å). It also can easily be observed to maintain the theory that translational interpenetration (Class I) favours higher degrees of interpenetration. To better understand the nature of this intricate framework, topology analysis is provided: the Zn cations and L1 ligands can be regarded as 4-connected nodes. Therefore, the whole structure can thus be represented as a 4-c net topology (with the Schläfli symbol {4.52.6.72} {4.52.62.7}{5.64.8}). (a)

(b)


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(c)

Figure 4. (a) Coordination environment of the Zn (II) ions in 4 (hydrogen atoms and sovent molecules are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = -1 + x, y, -1 + z; #2 = -1 + x, -1 + y, z; #3 = 1 - x, 1 - y, 1 - z. (b) Views of the 1D ladder-chain by L1 ligands and Zn ions. (c) Schematic view of three interpenetrating framework.

Crystal Structures of [Co(L2) (trans-chdc)(H2O)] ·1.5H2O (6) and [Co(L2) (1,4-bdc) (H2O)] · 2H2O (7). We considered changing the coordinated imidazole groups into the pyridine ligands to demonstrate that the effect of the different N-donor ligands in constructing the topology of MOFs. Therefore, L2 ligand was explored, and the complementary frameworks 6 and 7 were synthesized and characterized. Interestingly, only two nitrogen atoms of the L2 ligands in both compounds are involved in coordination. The deduced reason is that N-donor of pyridine exhibit weaker coordinative abilities because the electron densities on their nitrogen sites are comparatively lower than that of imidazole groups. As is shown in Figure 5a, the L2 ligands and trans-chdc anions both act as bidentate ligands assembling with Co(NO3)2 to a 2D framework (Figure 5b). Similar with the previously reported structure,17 all the wavy (4,4) 2D layers are stacked in an offset ABAB manner and the uncoordinated N atoms go through another set of 2D layer to form a mutual



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polythreading structure. When considering the H-bonds interaction (O1w-H1w2···N2), one of the uncoordinated N atoms of the A layer penetrates the B layer to connect the next A layers, thus forming a rare binodal 3,5-coordinated 3D architecture with a {63}{69.8} hms topology.18a One feature of this net is that it is a self-dual net, 18b so it is easy to form a 2-fold interpenetrating framework (Figure 5c). (a)

(b)

(c)

Figure 5. (a) The coordination environment of the Co (II) ions in 6. (hydrogen atoms and solvated water molecules are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = -1 + x, y, z; #2 = x, y, 1 + z. (b) A view of the 2D layer by L2 ligands, trans-chdc, and Co ions. (c) Schematic view of two interpenetrating framework with hms topology.

However, Compound 7 is a 3D network composed of layers which is bridged by


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the [Co2(CO2)4] SBUs and 1, 4-bdc ligands, and with L2 molecules between layers. The use of secondary building unit (SBU) instead of single metal ion at the network vertex is powerful in directing the final framework topology and structure.19 Compound 7 crystallizes in monoclinic crystal system of P21/c. The asymmetric unit contains one Co(II) cation, one L2 ligand, one deprotonated 1, 4-bdc ligand, one coordinated water and two free water molecules (Figure 6a). From a topological perspective, the SBU [Cd2(CO2)4] acts as a 6-connected node, and complex 7 represents {412.63} α-Po pcu topology by using both ligands as linkers (Figure 6b).

(a)

(b)

Figure 6. (a) The coordination environment of the Co (II) ions in 7 (hydrogen atoms and solvated water molecules are omitted for clarity, 30% ellipsoid probability), symmetry codes: #1 = -1 + x, y, 1 + z; #2 = x, 1.5 - y, 0.5 + z; #3 = - x, 0.5 + y, 1.5 - z. (b) Schematic view of α-Po topology. The effect of organic ligand: Design and syntheses of the metal-organic coordination compounds (Scheme 2), several factors should always be taken into consideration, such as the coordination properties of the metal ions, the organic ligands. Small changes in one or more can have a signaficant influence on the final strutures. In generally, the effect of the metal ion on MOF structure was found to be attributed to the coordination environment. However, based on the above study, the



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effect of organic ligand mainly reflected in the coordinative abilities and the rotation flexibility and conformations of L1 and L2. The N-donor of pyridine exhibits weaker coordinative ability, which may cause the pyridine groups of L2 ligand partly involved in coordination. Furthermore, the rotation flexibility and conformations of L1 and L2 play an important role in the formation of the compounds. The flexible Ndonor ligands adopt the conformations that hold four imidazole or pyridyl groups in a distorted tetrahedral orientation. Similar with previous reports 20, the distortion can be assessed by comparing the N–Ocore–N angles defined by the central oxygen atom and the coordinated nitrogen atoms of the imidazole or pyridyl groups. These angles show that ligands deviate significantly from tetrahedral geometry, as shown in Table S1. By comparison, we found that the imidazolate N-donor ligands are more inclined to rotate to coordinate to metal ions, which may cause a subtle influence on molecular self-assembly and topology and interpenetrating architectures. Therefore, Compounds 1-7 have various structure, the results showed that the different structures are evidently affected by the configuration of tetradentate ligands. The N– Ocore–N angles in compounds 1, 3, and 5 are approximative, therefore, they display common 2-fold interpenetration forms, however, compounds 2 and 4, with different configurations, show 4 and 3-fold interpenetration, respectively. Compared with imidazole ligands, L2 ligands with desired geometry and unconducive to rotate, have been more inclined to get specifically designed topologies.


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Scheme 2. Summary of all the structures UV-Visible Spectra. UV/Vis spectra of all Co compounds are in agreement with the coordination environment determined by X-ray single-crystal structure analysis. As can be seen in the UV-vis absorbance spectra in the Supporting Information (Figure S7), the UV-vis diffuse reflectance spectra showed similar absorption bands in the UV region, which corresponded to intraligand n→π* and π →π* transitions. In the visible region, we observe additional peaks at 480 nm [4T1g(F) → 4T2g(F)] [4T1g(F) → 4

T1g(P)] of octahedral CoII ions with a shoulder at 580 nm assigned to the [4A2g(F) →

4

T2g(P)] transition of tetrahedral CoII ions for 1.

21

For compounds 6 and 7, CoII ions

are both six-coordinated, so we observe two additional peaks at 470nm [4T1g(F) → 4

T2g(F)] with a shoulder at 550 nm [4T1g(F) → 4T1g(P)] and 730 nm assigned to the

4

T1g(F) → 4A2g(F) transitions.

Luminescent Properties and PXRD analyses: The coordination polymers with d10 metal centers have been investigated for fluorescence properties with potential applications in photochemistry, chemical sensors, and light-emitting diodes.22 The photoluminescence spectra of complexes 2-4, and the ligands were examined in the



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Page 18 of 25

solid state at room temperature (Table 1 and Figure S8). Emissions of the ligands were observed with wavelengths at 393 nm in L1 (λex= 356 nm), 420 nm (λex= 360 nm) in L2, 399 nm (λex= 346 nm) in 1, 4-bdc, which all could be attributed to the π*– π transitions. The emission peaks at 397 nm in 2 (λex= 340 nm), 380 nm in 3 (λex= 325 nm), and 413 nm in 4 (λex= 333 nm). All complexes are similar to that of the ligands, assigned to the intraligand fluorescent emissions.

23

Phase purity of the bulk

materials was confirmed by the comparison of their powder diffraction (PXRD) patterns with those calculated from single-crystal X-ray diffraction studies (Figures S9-S14).

Table 1. Luminescence data for organic ligands and coordination polymers in the solid state. Compound

λex[nm]

λem[nm]

Ligand

λex [nm]

λem[nm]

2

340

397

L1

356

393

3

325

380

1, 4-bdc

346

399

4

333

413

Thermal gravimetric analysis: Plots of thermal gravimetric analyses (TGA) of 1 - 4, 6 - 7 are shown in Figure S15. For complex 1, a weight loss is observed from 30 to 140°C which is attributed to the loss of the five lattice water molecules, with a weight loss of 8.54% (calcd 9.16%), then the ligands are removed from the complex. The TGA curve of 2 indicates that there is an initial weight loss of approximately 7.74% between 20 and 100 °C, corresponding to the loss of the guests (7.80% calcd for DMF molecule per unit formula). After the coordinated nitrate anions are gradually removed in the temperature range of 100-380 °C (calcd 9.83; found: 10.24%), then the decomposition of the ligands begins. The TGA curve of 3 is similar to 1, the H2O


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molecules are gradually removed at 50 °C (calcd 6.72; found: 6.20%), followed by a stable stage. The whole framework begins to collapse at about 250 °C. For Complex 4, a weight loss of 6.34% (calcd 5.70%) is observed from 20 to 80°C attributed to the loss of the three lattice water molecules, which were removed by the SQUEEZE routine in PLATON. Further weight loss indicates the decomposition of coordination framework from 170°C. The TGA curve of 6 is a 5.98% (calcd 6.01%) weight loss of two solvent and three coordinated water molecules from 70 to 110 °C, and the framework is collapsed. The TGA curve of 7 is similar to 6, the H2O molecules are gradually removed in the temperature range of 30–170°C (calcd 7.15; found: 7.62%). Then the whole framework begins to collapse.

Conclusion In summary, seven new coordination polymers with various architectures, based on two new neutral tetradentate ligands, have been prepared systematically to examine the effects of the core metal ion, and organic ligand on the topology of the assembly network. The effect of the metal ion on MOF structure was generally found to be attributed to the coordination environment, thereby permitting the synthesis of isostruture Co/Cd networks. Subsequent works will be focused on the structures and properties of a series of coordination compounds constructed by the two tetradentate ligands and other co-ligands. Work is also underway to determine the effects of temperature, solvent, and other effects on the composition and structure of the supramolecular assemblies.

■ASSOCIATED CONTENT Supporting Information Crystallographic data in CIF format, selected bond lengths and angles, and patterns of



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photochemistry, TGA, IR and PXRD. This information is available free of charge via the Internet at http://pubs.acs.org.

■AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] (H. Z.). Fax: 86-25-83314502. Nanjing University

■ ACKNOWLEDGMENTS This work was supported by grants from the Natural Science Foundation of China (Nos. 91022011; 20971065; 21021062), National Basic Research Program of China (2010CB923303; 2007CB925103).

References (1) (a) Ma, L.; Abney, C.; Lin, W. Chem. Soc. Rev. 2009, 38, 1248. (b) Yao, X. Q. ; Pan, Z. R. ; Hu, J. S. ; Li, Y. Z. ; Guo, Z. J. ; Zheng, H. G. Chem. Commun. 2011, 47, 10049. (c) Kurmoo, M.; Chem. Soc. Rev. 2009, 38, 1353. (d) Lu, Z. Z.; Zhang, R.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G. J. Am. Chem. Soc. 2011, 133, 4172. (e) Li, J. R.; Ma, Y. ; McCarthy, M. C. ; Sculley, J.; Yu, J.; Jeong, H. K.; Balbuena, P. B.; Zhou, H. C. Coord. Chem. Rev. 2011, 255, 1791. (2) (a) Duan, J.; Bai, J.; Zheng, B.; Li, Y.; Ren, W. Chem. Commun., 2011, 47, 2556. (b) Maji, T. K.; Matsuda, R.; Kitagawa, S. Naturematerials 2007, 142. (c) Yaghi, O. M. Naturematerials 2007, 92. (d) Galet, A.; Niel, V.; Munoz, M. C.; Real, J. J. Am. Chem. Soc. 2003, 125, 14224. (e) Reineke, T. M.; Eddaoudi, M.; Moler, D.; O'Keeffe, M.; Yaghi, O. M. J. Am. Chem. Soc. 2000, 122, 4843. (3) (a) Zhang, J.; Wojtas, L.; Larsen, R. W.; Eddaoudi, M.; Zaworotko, M. J. J. Am. Chem. Soc. 2009, 131, 17040. (b) Duan, J.; Bai, J.; Zheng, B.; Li, Y.; Ren, W.


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Chem. Commun. 2011, 2556. (c) Lankshear, M. D.; Beer, P. D. Acc. Chem. Res. 2007, 40, 657. (d) Zaman, M. B.; Smith, M. D.; Loye, H. C. Chem. Commun. 2001, 2256. (4) (a) Gadzikwa, T.; Zeng, B. S.; Hupp, J. T.; Nguyen, S. T. Chem. Commun. 2008, 3672. (b) Du, M.; Jiang, X. J.; Zhao, X. J. Inorg. Chem. 2007, 46, 3984. (5) (a) Hu, J. S.; Qin, L.; Zhang, M. D.; Yao, X. Q.; Li, Y. Z.; Guo, Z. J.; Zheng, H. G.; Xue, Z. L. Chem. Commun. 2012, 48, 681. (b) Metrangolo, P.; Meyer, F.; Pilati, T.; Proserpio, D. M.; Resnati, G. Chem. Eur. J. 2007, 13, 5765. (c) Natarajan, R.; Savitha, G.; Dominiak, P.; Wozniak, K.; Moorthy, J. N. Angew. Chem., Int. Ed. 2005, 44, 2115. (6) (a) Cho, J.; Hollis, T. K.; Valente, E. J.; Trate, J. M. J. Organomet. Chem. 2011, 696, 373. (b) Alam, M. A.; Tsuda, A.; Sei, Y.; Yamaguchi, K.; Aida, T. Tetrahedron 2008, 64, 8264. (7) SAINT, Version 6.02a; Bruker AXS Inc.: Madison, W1, 2002. (8) Sheldrick, G. M. SADABS, Program for Bruker Area Detector Absorption Correction, University of Göttingen, Göttingen, Germany, 1997. (9) (a) Chen, X. D.; Wan, C. Q.; Sung, H. H. Y.; Williams, I. D.; Mak, T. C. W. Chem. Eur. J. 2009, 15, 6518. (b) Henke, S.; Schmid, R.; Grunwaldt, J. D.; Fischer, R. A. Chem. Eur. J. 2010, 16, 14296. (c) Wang, J.; Lin, Z. J.; Ou, Y. C.; Shen, Y.; Herchel, R.; Tong, M. L. Chem. Eur. J. 2008, 14, 7218. (10) Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. J. Appl. Crystallogr. 2000, 33, 1193. (11) Platon Program: Spek, A. L. Acta Cryst. Sect. A. 1990, 46, 194. (12) (a) Blatov, V. A.; Carlucci, L.; Ciani, G.; Proserpio, D. M. CrystEngCom., 2004, 6, 377. (b) Baburin, I. A.; Blatov, V. A.; Carlucci, L.; Ciani, G.; Proserpio, D. M. CrystEngComm. 2008, 10, 1822. (c) Batten, S. R.; Robson, R. Angew. Chem., Int.



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Ed. 1998, 37, 1460. (d) Batten, S. R. CrystEngComm. 2001, 18, 1. (e) Carlucci, L. Ciani, G.; Proserpio, D. M. Coord. Chem. Rev. 2003, 246, 247. (13) Sun, D. F.; Ma, S. Q.; Ke, Y. X.; Petersen, T. M.; Zhou, H. C. Chem. Commun. 2005, 2663. (14) Zhao, Q. H.; Wang, Q. H.; Fang, R. B. Transition Met. Chem. 2004, 29, 144. (15) Medishetty, R.; Koh, L. L.; Kole, G. K.; Vittal, J. J. Angew. Chem., Int. Ed., 2011, 50, 10949. (16) Addison, A. A. W.; Rao, T. N.; Reedjik, J. ; Verschoor, G. C. J. J. Chem. Soc., Dalton Trans. 1984, 1349. (17) Qin, C.; Wang, X.; Carlucci, L.; Tong, M. L.; Wang, E. B.; Hu, C.; Xu, L. Chem. Commun. 2004, 1876. (18) (a) Zhang, H. X.; Wang, F.; Kang, Y.; Zhang, J. Inorg. Chem. Commun. 2010,13, 1429. (b) O’Keeffe, M. Aust. J. Chem. 1992, 45, 1489. (19) Eddaoudi, M.; Moler, D. B.; Li, H.; Chen, B.; Reineke, T. M.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2001, 34, 319. (b) Ockwig, N. W.; DelgadoFriedrichs, O.; O’Keeffe, M.; Yaghi, O. M. Acc. Chem. Res. 2005, 38, 176. (20) (a) Ryan, P. E.; Lescop, C.; Lalibertéé, D.; Hamilton, T.; Maris, T.; Wuest, J. D. Inorg. Chem. 2009, 48, 2793. (b) Zhang, Q.; Bu, X.; Lin, Z.; Wu, T.; Feng, P. Inorg. Chem. 2008, 47, 9724. (21) (a) Tonigold, M.; Lu, Y.; Mavrandonakis, A.; Puls, A.; Staudt, R.; Möllmer, J.; Sauer, J.; Volkmer, D. Chem. Eur. J. 2011, 17, 8671. (b) Sarma, D.; Ramanujachary, K. V.; Lofland, S. E.; Magdaleno, T.; Natarajan, S. Inorg. Chem. 2009, 48, 11660. (c) Figgis, B. N. In Comprehensive Coordination Chemistry; Wilkinson, G., Ed.; Pergamon: New York, 1987; Vol. 1, p259. (22) Allendorf, M. D.; Bauer, C. A.; Bhakta, R. K.; Houk, R. J. T. Chem. Soc. Rev. 2009, 38, 1330.


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(23) Lakowicz, J. R.; Principles of Fluorescence Spectroscopy; Plenum Press: New York, 1983. (b) Lentijo, S.; Miguel, J. A.; Espinet, P. Inorg. Chem. 2010, 49, 9169.



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For Table of Contents Use Only

Construction of Metal–Organic Frameworks Based on Two Neutral Tetradentate Ligands

Ling Qin, Jinsong Hu, Mingdao Zhang, Yizhi Li, and Hegen Zheng

It is interesting that the ligands show different geometries and connectivities as linkers in construsting MOFs. These MOFs exhibit different interpenetration forms and photochemical properties.


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Table 2. Crystal data and structural refinements parameters of complexes 1-7 Complex

1

2

3

4[a]

5[a]

6

7

Empirical formula

Co2C40H 48N 8O14

Zn2C35H38N11O 12

Cd2C40H 46N8O13

Zn2C40H 26N8O9

Cd 2C42H31N9O 10

Co2C80H 74 N8O 15

CoC40H32 N4O8

Mr

982.72

935.50

1071.65

893.43

1046.56

1505.33

755.63

Crystal system

monoclinic

monoclinic

monoclinic

triclinic

monoclinic

triclinic

monoclinic

Space group

P2/c

C2/c

P2/n

a (Å)

9.2407(14)

18.1006(11)

9.2708(9)

b (Å)

15.876(2)

15.2455(10)

16.9735(17)

13.201(3)

17.032(3)

13.0533(18)

21.024(3)

c (Å)

15.9418(18)

14.9908(9)

15.3137(15)

19.206(4)

14.414(2)

13.0557(18)

11.6070(15)

α (°)

90.00

90.00

90.00

90.00

86.458(2)

90.00

β (°)

110.773(7)

107.700(10)

103.345(2)

98.302(4)

90.697(3)

87.243(2)

94.390(2)

γ (°)

90.00

90.00

90.00

100.789(4)

90.00

79.259(2)

90.00

V (Å3)

2186.7(5)

3940.9(4)

2344.7(4)

2249.6(8)

2453.5(6)

1801.6(4)

3451.7(8)

P2/n

P 9.134(2)

9.9944(15)

90.00

1

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


P 10.7882(15)

P21/c 14.1863(18)

Z

2

4

2

2

2

1

4

ρcaled (g cm-3)

1.493

1.577

1.518

1.319

1.417

1.387

1.454

µ (mm 1)

0.834

1.294

0.975

1.124

0.926

0.535

0.560

λ(Å)

0.71073

0.71073

0.71073

0.71073

0.71073

0.71073

0.71073

T (K)

293(2)

296(2)

293(2)

291(2)

296(2)

296(2)

293(2)

GOF(F2)

1.031

1.032

0.970

1.061

1.051

1.060

1.097 0.0513

[b]

R1[I>2σ(I)]

0.0593

0.0462

0.0493

0.0718

0.0498

0.0342

wR2[I>2σ(I)][c]

0.1667

0.1310

0.1364

0.1973

0.1741

0.0883

0.1609

R1(all data)[b]

0.0755

0.0608

0.0646

0.1012

0.0554

0.0380

0.0594

wR2(all data)[c]

0.1759

0.1411

0.1430

0.2424

0.1831

0.0902

0.1660

[a] The residual electron densities were flattened by using the SQUEEZE option of PLATON. [b] “R1” =Σ||Fo|-|Fc||/|Σ|Fo|. [c] “wR2” ={Σ[w(Fo2-Fc2)2]/Σ[w(Fo2)2]}1/2; where w=1/[σ2(Fo2)+(aP)2+bP],P=(Fo2+2Fc2)/3.


Construction of MetalâOrganic Frameworks Based on Two Neutral

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