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Two new homometallic coordination polymers based on a carboxylate-functionalized salen ligand
Inorganic Chemistry Communications 55 (2015) 88–91
Contents lists available at ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
Two new homometallic coordination polymers based on a carboxylate-functionalized salen ligand Li-na Hao, Ying Lu ⁎, Zhen-Zhen He, Zhu-jun Liu, Enbo Wang ⁎ Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Renmin Street No. 5268, Changchun, Jilin 130024, PR China
a r t i c l e
i n f o
Article history: Received 2 February 2015 Received in revised form 27 February 2015 Accepted 14 March 2015 Available online 17 March 2015 Keywords: Salen-based Coordination polymer One-step synthesis Structure Fluorescent property
a b s t r a c t Two new homometallic coordination polymers 1 and 2 have been prepared by the directly one-step hydrothermal reactions of a carboxylate-functionalized salen ligand with Zn(II) and Co(II) ions, respectively. 1 exhibits a 3D open framework built by [Zn4(μ4-O)(carboxylate)8] units and double Zn-salen ligands, while 2 shows a 1D chain structure constructed by cobalt ions and the ligand derived from the hydrolysis to one C_N bond of salen ligand. The preliminary fluorescence measurements of 1–2 show the influence of structure on the property. © 2015 Elsevier B.V. All rights reserved.
Metal–organic frameworks (MOFs) have received much attention due to not only their versatile intriguing architectures and topologies tuned by metal ions and organic ligands, but also their properties for potential applications in various areas, such as catalysis, ion exchange, gas separation and storage, luminescence, magnetism and even in toxic gas removal [1]. Among the researches, design and construction of new MOFs with diverse structures have been drawing considerable attention. There is no doubt that organic ligands play a vital role in tuning the structural topology and functionality of MOFs. Salen complexes have also gained a great deal of recent interests thanks to their remarkable physical–chemical properties and biological activities, especially the extensive applications in catalytic chemistry [2]. It is not surprising that salen-based ligands have grown to be among the most widely explored ligands for coordination complexes owing to their easilyprepared, stronger nitrogen donated and modular designed. Considering the superiorities of both MOF materials and salen complexes, considerable impetus towards using salen complexes as ligands to construct MOFs has been provided [3]. Introducing functional groups such as carboxylate and pyridyl groups into the para- or meta-positions to the OH group of salen ligands [4] has been proved to be an effective strategy for constructing salen-based MOFs. A series of MOFs based on the carboxylate-functionalized salen ligand have been reported. For example, Cui et al. synthesized chiral nanoporous MOFs based on dicarboxyl-functionalized chiral Ni(salen) and Co(salen) ligands with square-planar Cd4 units [5], whereas Kitagawa et al. prepared an achiral Zn-MOF using M-salphdc (M = Cu(II), Co(II), and Ni(II); salphdc = N,N′⁎ Corresponding authors. E-mail addresses: [email protected] (Y. Lu), [email protected] (E. Wang).
http://dx.doi.org/10.1016/j.inoche.2015.03.026 1387-7003/© 2015 Elsevier B.V. All rights reserved.
phenylenebis(salicylideneimine)dicarboxylic acid) as linkers [4a]. Lin et al. reported a family of isoreticular chiral MOFs constructed from [Zn4(μ4-O)(O2CR)6] secondary building units and systematically elongated Mn-salen-derived dicarboxylic acid struts [6]. Commonly, the assembly process of salen-based MOFs contains two steps: Firstly, functionalized salen ligand coordinates to a metal center (M1) forming a metalloligand M-salen; and secondly, M-salen ligands acting as linkers react with another metal center (M2) acting as nodal units to form heterometallic MOFs. Therefore, to our knowledge, salen-based homometallic MOFs are rare [7]. Herein, we report the syntheses and characterizations of two new homometallic coordination polymers (1 and 2) that were formed directly from the one step reaction of salenderived dicarboxylate-bridging ligands (H4L) and transition metal ions (M = Co and Zn). As shown in Scheme 1, the reaction of ZnCl2 with the H4L in H2O/ MeOH at 80 °C for 72 h [8b] afforded purple block single crystals of 1. Single-crystal X-ray diffraction [9] reveals that 1 crystallizes in the Pban space group and possesses a 3D open framework based on a tetranuclear SBU. There are two distinct zinc coordination environments in 1: one (Zn1) is located in the center of the salen ligand and is coordinated in a distorted square-planar geometry with two nitrogen atoms and two oxygen atoms from the H4L ligand to form a metalloligand ZnL, while the other (Zn2) exhibits a distorted tetragonal pyramid geometry defined by one central μ4-O atom, two oxygen atoms from one bidentate carboxylate group and two oxygen atoms respectively from two monodentate carboxylate groups. Four Zn2 centers are held together by a central μ4-O atom adopting a tetrahedral geometry with Zn–O bond lengths ranging from 1.931 (9) to 1.986 (0) Å, and eight carboxylate groups from eight ZnL ligands coordinate to the four
L. Hao et al. / Inorganic Chemistry Communications 55 (2015) 88–91
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Scheme 1. Synthesis of compounds 1 and 2.
Zn2 centers to form a [Zn4(μ4-O)(carboxylate)8] SBU (Fig. 1). In 1, each antiparallel double ZnL ligands are linked to two Zn4 SBUs, and each Zn4 SBU is connected with eight ZnL ligands generating a 3D porous framework with square channels of 13.009 × 18.717 Å2 along the c-axis. Calculations using PLATON show that 1 has about 27% of the total volume available for guest inclusion. The preparation process of 2 [8c] is similar to 1 except that CoCl2·6H2O is adopted instead of ZnCl2 (Scheme 1). Detailed analysis of the single-crystal X-ray diffraction data [9] reveals that 2 adopts a 1D chain structure and crystallizes in the space group P-1. In 2, there happens the hydrolysis to one C_N bond of each H4L ligand, so that each Co(III) (calculated by bond valences) center adopts an octahedral geometry by coordinating to two pairs of N2O donor from two hydrolyzed H4Ls, which planes are perpendicular to each other (Fig. S4). Moreover, each hydrolyzed H4L ligand uses one monodentate carboxylate group to bind adjacent Co(II) center to form 1D coordination polymeric chains (Fig. 2). Two H2O molecules serve as terminal ligands to complete the octahedral coordination geometry of the Co(II) center. The hydrogen atoms linked to the amine of hydrolyzed H4L ligand in the polymeric chains are pointing outward and are well positioned to form strong hydrogen bonds with the uncoordinated deprotonated carboxylate oxygen atoms (O⋯N, 2.889 (1) Å) of adjacent chains leading to a 2D network (Fig. S5). Further, the inter π⋯π interactions between layers drive the 2D network into a 3D framework (Fig. S5). The IR spectrum of H4L (Fig. S1.1) displays a band at 1208 cm− 1 assigned to the –Ph–O asymmetric stretch vibration. In 1 (Fig. S1.2) and 2 (Fig. S1.3), this band shifts to the 1184 and 1192 cm−1 respective-
ly, indicating the participation in coordination. Besides, the red-shift Δυ (υ (C_N)–υ (C_N)) of 20 cm− 1, suggests the coordination of the azomethine group and center metals, which softens the intensity of C_N vibration. The characteristic absorption bands at 1400– 1600 cm−1 are owing to the aromatic C_C vibration. The thermal gravimetric analyses (TGAs) of 1 and 2 were performed to investigate their thermal behavior (Fig. S2). The TGA of compound 1 reveals that the lattice water molecules are lost at the temperature 35– 114 °C (obsd 13.78%, calcd 12.83%). Then the compound is stable up to 332 °C. In the temperature range of 315–480 °C, two continuous weight losses (51.19%) are observed due to the decomposition of the salen ligands, which is in agreement with the calculated value 51.34%. For 2, the first weight loss is 9.11% (calcd 8.12%) in the temperature range from 47 to 161 °C, which corresponds to the release of lattice and coordinated water molecules in the structure. Then the compound is stable up to 250 °C. At higher temperature, two continuous weight losses of about 72.16% occur from 250 to 480 °C assigned to the losses of the salen ligands (calcd 73.75%). Preliminary fluorescence of 1–2 together with H4L is measured at room temperature. As shown in Fig. 3, 1 exhibits an intense emission band at 447 nm, in the solid state upon excitation at 370 nm, along with the blue shift. That may be assigned to the π*–π or π*–n transition of intraligand because of the difficulty for Zn(II) ion (d10 configuration) to oxidize or reduce [12]. And the emission spectrum of 2 consists of a broad band with a maximum at about 556 nm (λex = 380 nm), and appears red-shifted compared to the free H4L ligand, which is presumably due to the intermolecular interactions (such as π–π stacking) between
Fig. 1. (a) View of the local connections' tetranuclear zinc units and H4L ligands. (b) Projection diagram of 1 down the c axis showing the 3D porous framework.
Fig. 2. View of the forming process of 1D chain in 2.
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L. Hao et al. / Inorganic Chemistry Communications 55 (2015) 88–91
[2]
Fig. 3. Fluorescent spectra of compounds 1, 2 and H4L in the solid state at room temperature (λex = 370, 380 and 333 nm for 1, 2 and H4L).
the molecules. Notably, compared to the free ligand H4L ligand, 1 and 2 show weakened intensity and shifted emission spectrum, proving that metal ions in the structures may change intraligand transitions. In summary, we have constructed two new coordination polymers based on dicarboxylate-functionalized salen ligand and transition metals. It is noteworthy that both the compounds are prepared by one-step synthesis without the process of “metalloligand” (ML), which represent the rare examples of homometallic salen-based MOFs. Hence, it is believed that this will open up a promising approach to prepare new salen-based MOF materials. Besides, distinctly different fluorescent properties of 1–2 also provide new insights into the relationship between the structures and properties of these materials.
Acknowledgments
[3]
[4]
This work was financially supported by the National Natural Science Foundation of China (No. 20901015), the Science and Technology Development Project Foundation of Jilin Province (No. 20130101006JC), and the National Grand Fundamental Research 973 Program of China (2010CB635114).
Appendix A. Supplementary material CCDC 1046124 and 1046122 contain the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam. ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version at http://dx.doi.org/10.1016/j. inoche.2015.03.026.
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Cui, Enantioselective recognition and separation by a homochiral porous lamellar solid based on unsymmetrical schiff base metal complexes, Chem. Eur. J. 15 (2009) 6428–6434; (b) Y.W. Peng, C.F. Zhu, Y. Cui, Synthesis, structure and property of one porous Zn(salen)-based metal–metallosalen framework, Sci. China Chem. 57 (2014) 107–113. (a) Synthesis of H4L: 3-formyl-4-hydroxybenzoic acid was obtained by the Reimer– Tiemann reaction [10a] of 4-hydroxybenzoic acid with chloroform. A solution of trans-1,2-diaminocyclohexane (0.228 g, 2 mmol) in 10 mL of ethanol was added dropwise to a solution of (0.665 g, 4 mmol) 4-formyl 3-hydroxybenzoic acid in 20 mL ethanol. The reaction mixture was stirred for 2 hours at 60 °C. The yellow solid was filtered and washed with 10 mL cold ethanol and dried in vacuo. (b) Synthesis of 1: A solution of ZnCl2 (100 mg, 0.73 mmol) in H2O (10 mL) was added dropwise to the H4L (100 mg, 0.24 mmol) in MeOH (15 mL). Subsequently [(C4H9)4N]H[PW11Cu(H2O)O39] (100 mg, 0.033 mmol) [10b] was added and the resulting mixture was stirred for 10 min in air. The mixture was adjusted the pH
L. Hao et al. / Inorganic Chemistry Communications 55 (2015) 88–91 to 8.8 with ammonium hydroxide, then transferred to and sealed in 15 mL Teflonlined reactors, heated in an oven to 80 °C for 72 h. The resulting purple block crystals were washed with MeOH, filtered, and dried in air (yield 0.01 g, ca. 10% based on H4L). Anal.Calcd (%): C, 41.84; H, 4.28; N, 4.44; Zn, 20.72; Cl, 1.41. Found (%): C, 41.75; H, 4.32; N, 4.47; Zn, 20.63; Cl, 1.50. (c) Synthesis of 2: The preparation process of 2 was similar to 1 except that CoCl2·6H2O (123 mg, 0.5 mmol) was adopted instead of ZnCl2. Brown block crystals of 2 were obtained after washed with MeOH, filtered, and dried in air (yield 0.02 g, ca. 20 %, based on H4L). Anal.Calcd (%): C, 50.53; H, 6.02; N, 8.42; Co, 13.29. Found (%): C, 50.33; H, 6.28; N, 8.38; Co, 13.35. [9] X-ray diffraction data were collected with a Bruker AXS SMART 1K CCD diffractometer, using graphite-monochromated Mo-KR radiation at ambient temperature. Data collection and reduction were performed using the SMART and SAINT software [11a]. A multi-scan absorption correction was applied using the SADABS program [11b]. The structure was solved by direct methods and refined by full-matrix least squares on F2 using the SHELXTL program package [11c]. Crystallographic data for compound 1: C88H108ClN8O43Zn8, Fw = 2524.15, Orthorhombic, Space group Pban with a = 24.673(3) Å, b = 24.911(3) Å, c = 9.3725(12) Å, V = 5760.6(12) Å3, Z = 2, F(000) = 2486, GOF = 1.053, R1 = 0.0993, and wR2 = 0.2664 [I ≥ 2 σ(I)]. Crystallographic data for compound 2: C56H80Co3N8O18, Fw = 1253.97, Triclinic,
91
Space group P1 with a = 10.046(3) Å, b = 12.364(4) Å, c = 13.715(4) Å, α = 79.292(4)°, β = 71.928(4)°, γ = 80.862(4)°, V = 1581.9(8) Å 3 , Z = 2, F(000) = 653, GOF = 1.066, R1 = 0.0602, and wR2 = 0.1234 [I ≥ 2 σ (I)]. [10] (a) H. Wynberc, Some observations on the mechanism of the Reimer–Tiemann reaction, J. Am. Chem. Soc. 76 (1954) 4998–4999; (b) C.M. Tourné, G.F. Tourné, Triheteropolyanins containing copper(II), manganese(II) or manganese(III), J. Inorg. Nucl. Chem. 732 (1970) 3875–3890. [11] (a) G.M. Sheldrick, SADABS Program for Scaling and Correction of Area Detector Data, University of Göttingen, Göttingen, Germany, 1996; (b) Bruker, APEXII Software, Version 6.3.1, Bruker AXS Inc., Madison, Wisconsin, USA, 2004; (c) G.M. Sheldrick, SHELXL-97, Program for X-ray Crystal Structure Refinement, University of Göttingen, Göttingen, Germany, 1997. [12] (a) T.L. Hu, R.Q. Zou, J.R. Li, X.H. Bu, d10 Metal complexes assembled from isomeric benzenedicarboxylates and 3-(2-pyridyl)pyrazole showing 1D chain structures: syntheses, structures and luminescent properties, Dalton Trans. 1302–1311 (2008); (b) Y. Ma, X. Tang, W. Yin, B. Wu, F. Xue, R. Yuan, S. Roy, Zinc and cadmium 2pyrazinephosphonates: syntheses, structures and luminescent properties, Dalton Trans. (41) (2012) 2340–2345.
Contents lists available at ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
Two new homometallic coordination polymers based on a carboxylate-functionalized salen ligand Li-na Hao, Ying Lu ⁎, Zhen-Zhen He, Zhu-jun Liu, Enbo Wang ⁎ Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Renmin Street No. 5268, Changchun, Jilin 130024, PR China
a r t i c l e
i n f o
Article history: Received 2 February 2015 Received in revised form 27 February 2015 Accepted 14 March 2015 Available online 17 March 2015 Keywords: Salen-based Coordination polymer One-step synthesis Structure Fluorescent property
a b s t r a c t Two new homometallic coordination polymers 1 and 2 have been prepared by the directly one-step hydrothermal reactions of a carboxylate-functionalized salen ligand with Zn(II) and Co(II) ions, respectively. 1 exhibits a 3D open framework built by [Zn4(μ4-O)(carboxylate)8] units and double Zn-salen ligands, while 2 shows a 1D chain structure constructed by cobalt ions and the ligand derived from the hydrolysis to one C_N bond of salen ligand. The preliminary fluorescence measurements of 1–2 show the influence of structure on the property. © 2015 Elsevier B.V. All rights reserved.
Metal–organic frameworks (MOFs) have received much attention due to not only their versatile intriguing architectures and topologies tuned by metal ions and organic ligands, but also their properties for potential applications in various areas, such as catalysis, ion exchange, gas separation and storage, luminescence, magnetism and even in toxic gas removal [1]. Among the researches, design and construction of new MOFs with diverse structures have been drawing considerable attention. There is no doubt that organic ligands play a vital role in tuning the structural topology and functionality of MOFs. Salen complexes have also gained a great deal of recent interests thanks to their remarkable physical–chemical properties and biological activities, especially the extensive applications in catalytic chemistry [2]. It is not surprising that salen-based ligands have grown to be among the most widely explored ligands for coordination complexes owing to their easilyprepared, stronger nitrogen donated and modular designed. Considering the superiorities of both MOF materials and salen complexes, considerable impetus towards using salen complexes as ligands to construct MOFs has been provided [3]. Introducing functional groups such as carboxylate and pyridyl groups into the para- or meta-positions to the OH group of salen ligands [4] has been proved to be an effective strategy for constructing salen-based MOFs. A series of MOFs based on the carboxylate-functionalized salen ligand have been reported. For example, Cui et al. synthesized chiral nanoporous MOFs based on dicarboxyl-functionalized chiral Ni(salen) and Co(salen) ligands with square-planar Cd4 units [5], whereas Kitagawa et al. prepared an achiral Zn-MOF using M-salphdc (M = Cu(II), Co(II), and Ni(II); salphdc = N,N′⁎ Corresponding authors. E-mail addresses: [email protected] (Y. Lu), [email protected] (E. Wang).
http://dx.doi.org/10.1016/j.inoche.2015.03.026 1387-7003/© 2015 Elsevier B.V. All rights reserved.
phenylenebis(salicylideneimine)dicarboxylic acid) as linkers [4a]. Lin et al. reported a family of isoreticular chiral MOFs constructed from [Zn4(μ4-O)(O2CR)6] secondary building units and systematically elongated Mn-salen-derived dicarboxylic acid struts [6]. Commonly, the assembly process of salen-based MOFs contains two steps: Firstly, functionalized salen ligand coordinates to a metal center (M1) forming a metalloligand M-salen; and secondly, M-salen ligands acting as linkers react with another metal center (M2) acting as nodal units to form heterometallic MOFs. Therefore, to our knowledge, salen-based homometallic MOFs are rare [7]. Herein, we report the syntheses and characterizations of two new homometallic coordination polymers (1 and 2) that were formed directly from the one step reaction of salenderived dicarboxylate-bridging ligands (H4L) and transition metal ions (M = Co and Zn). As shown in Scheme 1, the reaction of ZnCl2 with the H4L in H2O/ MeOH at 80 °C for 72 h [8b] afforded purple block single crystals of 1. Single-crystal X-ray diffraction [9] reveals that 1 crystallizes in the Pban space group and possesses a 3D open framework based on a tetranuclear SBU. There are two distinct zinc coordination environments in 1: one (Zn1) is located in the center of the salen ligand and is coordinated in a distorted square-planar geometry with two nitrogen atoms and two oxygen atoms from the H4L ligand to form a metalloligand ZnL, while the other (Zn2) exhibits a distorted tetragonal pyramid geometry defined by one central μ4-O atom, two oxygen atoms from one bidentate carboxylate group and two oxygen atoms respectively from two monodentate carboxylate groups. Four Zn2 centers are held together by a central μ4-O atom adopting a tetrahedral geometry with Zn–O bond lengths ranging from 1.931 (9) to 1.986 (0) Å, and eight carboxylate groups from eight ZnL ligands coordinate to the four
L. Hao et al. / Inorganic Chemistry Communications 55 (2015) 88–91
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Scheme 1. Synthesis of compounds 1 and 2.
Zn2 centers to form a [Zn4(μ4-O)(carboxylate)8] SBU (Fig. 1). In 1, each antiparallel double ZnL ligands are linked to two Zn4 SBUs, and each Zn4 SBU is connected with eight ZnL ligands generating a 3D porous framework with square channels of 13.009 × 18.717 Å2 along the c-axis. Calculations using PLATON show that 1 has about 27% of the total volume available for guest inclusion. The preparation process of 2 [8c] is similar to 1 except that CoCl2·6H2O is adopted instead of ZnCl2 (Scheme 1). Detailed analysis of the single-crystal X-ray diffraction data [9] reveals that 2 adopts a 1D chain structure and crystallizes in the space group P-1. In 2, there happens the hydrolysis to one C_N bond of each H4L ligand, so that each Co(III) (calculated by bond valences) center adopts an octahedral geometry by coordinating to two pairs of N2O donor from two hydrolyzed H4Ls, which planes are perpendicular to each other (Fig. S4). Moreover, each hydrolyzed H4L ligand uses one monodentate carboxylate group to bind adjacent Co(II) center to form 1D coordination polymeric chains (Fig. 2). Two H2O molecules serve as terminal ligands to complete the octahedral coordination geometry of the Co(II) center. The hydrogen atoms linked to the amine of hydrolyzed H4L ligand in the polymeric chains are pointing outward and are well positioned to form strong hydrogen bonds with the uncoordinated deprotonated carboxylate oxygen atoms (O⋯N, 2.889 (1) Å) of adjacent chains leading to a 2D network (Fig. S5). Further, the inter π⋯π interactions between layers drive the 2D network into a 3D framework (Fig. S5). The IR spectrum of H4L (Fig. S1.1) displays a band at 1208 cm− 1 assigned to the –Ph–O asymmetric stretch vibration. In 1 (Fig. S1.2) and 2 (Fig. S1.3), this band shifts to the 1184 and 1192 cm−1 respective-
ly, indicating the participation in coordination. Besides, the red-shift Δυ (υ (C_N)–υ (C_N)) of 20 cm− 1, suggests the coordination of the azomethine group and center metals, which softens the intensity of C_N vibration. The characteristic absorption bands at 1400– 1600 cm−1 are owing to the aromatic C_C vibration. The thermal gravimetric analyses (TGAs) of 1 and 2 were performed to investigate their thermal behavior (Fig. S2). The TGA of compound 1 reveals that the lattice water molecules are lost at the temperature 35– 114 °C (obsd 13.78%, calcd 12.83%). Then the compound is stable up to 332 °C. In the temperature range of 315–480 °C, two continuous weight losses (51.19%) are observed due to the decomposition of the salen ligands, which is in agreement with the calculated value 51.34%. For 2, the first weight loss is 9.11% (calcd 8.12%) in the temperature range from 47 to 161 °C, which corresponds to the release of lattice and coordinated water molecules in the structure. Then the compound is stable up to 250 °C. At higher temperature, two continuous weight losses of about 72.16% occur from 250 to 480 °C assigned to the losses of the salen ligands (calcd 73.75%). Preliminary fluorescence of 1–2 together with H4L is measured at room temperature. As shown in Fig. 3, 1 exhibits an intense emission band at 447 nm, in the solid state upon excitation at 370 nm, along with the blue shift. That may be assigned to the π*–π or π*–n transition of intraligand because of the difficulty for Zn(II) ion (d10 configuration) to oxidize or reduce [12]. And the emission spectrum of 2 consists of a broad band with a maximum at about 556 nm (λex = 380 nm), and appears red-shifted compared to the free H4L ligand, which is presumably due to the intermolecular interactions (such as π–π stacking) between
Fig. 1. (a) View of the local connections' tetranuclear zinc units and H4L ligands. (b) Projection diagram of 1 down the c axis showing the 3D porous framework.
Fig. 2. View of the forming process of 1D chain in 2.
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[2]
Fig. 3. Fluorescent spectra of compounds 1, 2 and H4L in the solid state at room temperature (λex = 370, 380 and 333 nm for 1, 2 and H4L).
the molecules. Notably, compared to the free ligand H4L ligand, 1 and 2 show weakened intensity and shifted emission spectrum, proving that metal ions in the structures may change intraligand transitions. In summary, we have constructed two new coordination polymers based on dicarboxylate-functionalized salen ligand and transition metals. It is noteworthy that both the compounds are prepared by one-step synthesis without the process of “metalloligand” (ML), which represent the rare examples of homometallic salen-based MOFs. Hence, it is believed that this will open up a promising approach to prepare new salen-based MOF materials. Besides, distinctly different fluorescent properties of 1–2 also provide new insights into the relationship between the structures and properties of these materials.
Acknowledgments
[3]
[4]
This work was financially supported by the National Natural Science Foundation of China (No. 20901015), the Science and Technology Development Project Foundation of Jilin Province (No. 20130101006JC), and the National Grand Fundamental Research 973 Program of China (2010CB635114).
Appendix A. Supplementary material CCDC 1046124 and 1046122 contain the supplementary crystallographic data for 1 and 2. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam. ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version at http://dx.doi.org/10.1016/j. inoche.2015.03.026.
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Cui, Enantioselective recognition and separation by a homochiral porous lamellar solid based on unsymmetrical schiff base metal complexes, Chem. Eur. J. 15 (2009) 6428–6434; (b) Y.W. Peng, C.F. Zhu, Y. Cui, Synthesis, structure and property of one porous Zn(salen)-based metal–metallosalen framework, Sci. China Chem. 57 (2014) 107–113. (a) Synthesis of H4L: 3-formyl-4-hydroxybenzoic acid was obtained by the Reimer– Tiemann reaction [10a] of 4-hydroxybenzoic acid with chloroform. A solution of trans-1,2-diaminocyclohexane (0.228 g, 2 mmol) in 10 mL of ethanol was added dropwise to a solution of (0.665 g, 4 mmol) 4-formyl 3-hydroxybenzoic acid in 20 mL ethanol. The reaction mixture was stirred for 2 hours at 60 °C. The yellow solid was filtered and washed with 10 mL cold ethanol and dried in vacuo. (b) Synthesis of 1: A solution of ZnCl2 (100 mg, 0.73 mmol) in H2O (10 mL) was added dropwise to the H4L (100 mg, 0.24 mmol) in MeOH (15 mL). Subsequently [(C4H9)4N]H[PW11Cu(H2O)O39] (100 mg, 0.033 mmol) [10b] was added and the resulting mixture was stirred for 10 min in air. The mixture was adjusted the pH
L. Hao et al. / Inorganic Chemistry Communications 55 (2015) 88–91 to 8.8 with ammonium hydroxide, then transferred to and sealed in 15 mL Teflonlined reactors, heated in an oven to 80 °C for 72 h. The resulting purple block crystals were washed with MeOH, filtered, and dried in air (yield 0.01 g, ca. 10% based on H4L). Anal.Calcd (%): C, 41.84; H, 4.28; N, 4.44; Zn, 20.72; Cl, 1.41. Found (%): C, 41.75; H, 4.32; N, 4.47; Zn, 20.63; Cl, 1.50. (c) Synthesis of 2: The preparation process of 2 was similar to 1 except that CoCl2·6H2O (123 mg, 0.5 mmol) was adopted instead of ZnCl2. Brown block crystals of 2 were obtained after washed with MeOH, filtered, and dried in air (yield 0.02 g, ca. 20 %, based on H4L). Anal.Calcd (%): C, 50.53; H, 6.02; N, 8.42; Co, 13.29. Found (%): C, 50.33; H, 6.28; N, 8.38; Co, 13.35. [9] X-ray diffraction data were collected with a Bruker AXS SMART 1K CCD diffractometer, using graphite-monochromated Mo-KR radiation at ambient temperature. Data collection and reduction were performed using the SMART and SAINT software [11a]. A multi-scan absorption correction was applied using the SADABS program [11b]. The structure was solved by direct methods and refined by full-matrix least squares on F2 using the SHELXTL program package [11c]. Crystallographic data for compound 1: C88H108ClN8O43Zn8, Fw = 2524.15, Orthorhombic, Space group Pban with a = 24.673(3) Å, b = 24.911(3) Å, c = 9.3725(12) Å, V = 5760.6(12) Å3, Z = 2, F(000) = 2486, GOF = 1.053, R1 = 0.0993, and wR2 = 0.2664 [I ≥ 2 σ(I)]. Crystallographic data for compound 2: C56H80Co3N8O18, Fw = 1253.97, Triclinic,
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Space group P1 with a = 10.046(3) Å, b = 12.364(4) Å, c = 13.715(4) Å, α = 79.292(4)°, β = 71.928(4)°, γ = 80.862(4)°, V = 1581.9(8) Å 3 , Z = 2, F(000) = 653, GOF = 1.066, R1 = 0.0602, and wR2 = 0.1234 [I ≥ 2 σ (I)]. [10] (a) H. Wynberc, Some observations on the mechanism of the Reimer–Tiemann reaction, J. Am. Chem. Soc. 76 (1954) 4998–4999; (b) C.M. Tourné, G.F. Tourné, Triheteropolyanins containing copper(II), manganese(II) or manganese(III), J. Inorg. Nucl. Chem. 732 (1970) 3875–3890. [11] (a) G.M. Sheldrick, SADABS Program for Scaling and Correction of Area Detector Data, University of Göttingen, Göttingen, Germany, 1996; (b) Bruker, APEXII Software, Version 6.3.1, Bruker AXS Inc., Madison, Wisconsin, USA, 2004; (c) G.M. Sheldrick, SHELXL-97, Program for X-ray Crystal Structure Refinement, University of Göttingen, Göttingen, Germany, 1997. [12] (a) T.L. Hu, R.Q. Zou, J.R. Li, X.H. Bu, d10 Metal complexes assembled from isomeric benzenedicarboxylates and 3-(2-pyridyl)pyrazole showing 1D chain structures: syntheses, structures and luminescent properties, Dalton Trans. 1302–1311 (2008); (b) Y. Ma, X. Tang, W. Yin, B. Wu, F. Xue, R. Yuan, S. Roy, Zinc and cadmium 2pyrazinephosphonates: syntheses, structures and luminescent properties, Dalton Trans. (41) (2012) 2340–2345.