English

• 0.   Introduction

  Metal-organic frameworks (MOFs) not only show exquisite microstructures and topology diversity^[1-3] but also have many potential applications in gas storage and separation, catalysis, luminescence sensing, drug delivery, etc^[4-7]. Given these favorable characteristics, syntheses of MOFs have become a research hotspot in the fields of inorganic chemistry and materials science. Because MOFs are constructed by metal ions/clusters and organic ligands^[8], the inherent properties of carefully designed/selected metal ions and organic ligands can endow MOFs with some unique functions^[9-11]. For example, the photoluminescent properties of MOFs can be adjusted by changing the metal centers and ligands in the hybrid system^[12].

  However, the final structures of MOFs are affected by many reaction factors, such as solvent system, ligand structure, temperature, pH, and metal ions species. Therefore, it is difficult to synthesize MOFs with excellent structure^[13]. Fortunately, organic ligands play a key role in the process of synthesizing MOFs. Among a variety of organic ligands, aromatic polycarboxylic acid and nitrogen heterocyclic ligands have a strong coordination ability with metal ions^[14-15]. So, it is a good choice to obtain target MOFs by using different nitrogen heterocyclic derivatives and aromatic carboxylic acids as ligands.

  As one of the aromatic carboxylic acids, 2, 5-dimethoxyterephthalic acid (H₂DTA) is an effective linker for its own advantages: (1) two rigid carboxylate groups indicate rich coordination sites; (2) two methoxy groups as electron-donating groups can increase the nucleophilicity of ligand^[16-17]. Based on aforementioned search backgrounds, H₂DTA was selected to help midazole derivatives 1, 2, 4, 5-tetra(1H-imidazol-1-yl)benzene (1, 2, 4, 5-TIB), 1, 4-bis(4-methyl-1H-imidazol-1-yl) benzene (1, 4-BMIB) and 1, 4-bis(4-methyl-1H-imidazol-1-yl)naphthalene (1, 4-BMIN) to assemble with Zn(Ⅱ) to build MOFs (Scheme 1). As a result, three 3D (three-dimensional) MOFs, namely {[Zn(DTA)(1, 2, 4, 5-TIB)_0.5]·1.5H₂O}_n (1), [Zn(DTA)(1, 4-BMIB)_0.5(H₂O)]_n (2), and {[Zn(DTA) (1, 4-BMIN)] ·H₂O}_n (3), were prepared under solvothermal condition. Herein, their syntheses, structures, and fluorescence properties are reported.

  Scheme 1

  

  Scheme 1.  Structures of H₂DTA, 1, 3, 4, 5-TIB, 1, 4-BMIB, and 1, 4-BMIN

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  1.   Experimental

  1.1   Reagents and instruments

  All chemicals were commercially available and used without further purification. Powder X-ray diffraction (PXRD) patterns were performed on a Rigaku MiniFlex 600 diffractometer (Voltage: 40 kV, Current: 15 mA, Cu Kα radiation, λ=0.154 060 nm) in a range of 5.00° to 50.00°. Thermogravimetric analyses (TGA) data were collected by a NETSCHZ STA-F3 thermoanalyzer from room temperature to 800 ℃, respectively. IR spectra were measured as KBr pellets from 400 to 4 000 cm^-1 on a Tianjin Gangdong 7600 FT-IR spectrometer.

  1.2   Synthesis of MOF 1

  Zn(BF₄)₂·6H₂O (36 mg, 0.15 mmol), H₂DTA (22 mg, 0.10 mmol), and 1, 2, 4, 5-TIB (34 mg, 0.10 mmol) were dissolved in a mixed solvent of H₂O (4 mL) and N, N-dimethylformamide (1 mL). Then, the resulting solution was stirred for 30 min and put into a 20 mL glass vial, and heated at 80 ℃ for 3 d. The colorless block crystals were obtained and washed with ethanol and dried in the air with a yield of 35% (based on H₂DTA). Anal. Calcd. for C₁₉H₁₈N₄O_7.5Zn(%): C, 46.79; H, 3.72; N, 11.49. Found(%): C, 45.83; H, 3.58; N, 11.62. IR (KBr pellet, cm^-1): 3 408m, 3 107w, 3 017w, 1 592s, 1 530s, 1 488s, 1 460m, 1 403m, 1 257m, 1 348s, 1 232m, 1 208s, 1 068m, 1 034m, 985w, 935w, 859w, 817w, 796w, 761w, 650w, 629w, 530w.

  1.3   Synthesis of MOF 2

  Zn(NO₃)₂·6H₂O (45 mg, 0.15 mmol), H₂DTA (22 mg, 0.10 mmol), and 1, 4-BMIB (23 mg, 0.10 mmol) were placed in a 5 mL mixed solvent of N, N-diethylformamide (DEF) and H₂O (4∶1, V/V) and stirred for 10 min. Then, the resulting solution was heated at 100 ℃ for 3 d. The colorless block crystals of 2 were obtained with a yield of 53% (based on H₂DTA). Anal. Calcd. for C₁₇H₁₇N₂O₇Zn(%): C, 47.85; H, 4.02; N, 6.57. Found (%): C, 47.36; H, 3.91; N, 6.74. IR (solid KBr pellet, cm^-1): 3 491m, 3 129w, 2 947w, 1 586s, 1 522m, 1 494m, 1 439m, 1 411s, 1 348s, 1 285m, 1 243m, 1 208s, 1 135w, 1 027m, 887w, 845w, 748w, 650w, 552w.

  1.4   Synthesis of MOF 3

  Zn(NO₃)₂·6H₂O (45 mg, 0.15 mmol), H₂DTA (22 mg, 0.10 mmol), and 1, 4-BMIN (28 mg, 0.10 mmol) were placed in a 4 mL mixed solvent of DEF, H₂O, and methanol (2∶1∶1, V/V) and stirred for 30 min. The final suspending solution was put into a 20 mL glass vial and heated at 100 ℃ for 3 d. The colorless block crystals of 3 were obtained with a yield of 61% (based on H2DTA). Anal. Calcd. for C₂₈H₂₆N₄O₇Zn(%): C, 56.44; H, 4.40; N, 9.40. Found(%): C, 57.56; H, 4.23; N, 9.45. IR (solid KBr pellet, cm^-1): 3 477w, 3 101w, 2 954w, 2 921w, 2 836w, 1 600s, 1 502w, 1 439m, 1 389m, 1 341m, 1 278s, 1 208s, 1 174w, 1 124w, 1 027m, 935w, 845w, 775m, 754m, 664w, 636w, 440w.

  1.5   Determination of the structure

  The data of three single crystals with dimensions of 0.2 mm×0.1 mm×0.1 mm (1), 0.20 mm× 0.20 mm× 0.20 mm (2), and 0.30 mm×0. 2 mm×0.20 mm (3) were obtained on a Rigaku 003 CCD diffractometer with a Mo Kα radiation (λ =0.071 073 nm) at room temperature, respectively. Their structures were solved via the SHELXT-2014 program and refined by SHELXL-2017 on Olex2-1.2 software^[18-19]. All non-hydrogen atoms were refined anisotropically. The H atoms from C atoms were positioned geometrically and disposed of by using a riding model, and the H atoms from H₂O moieties were located by difference maps and constrained to ride on their parent O atoms. The crystal data and refinement parameters for 1, 2, and 3 are summarized in Table 1, and some selected bond lengths and angles are listed in Table S1 (Supporting information).

  Table 1

  

  Table 1.  Crystallographic data and refinement parameters for MOFs 1-3

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  Parameter	1	2	3
  Empirical formula	C19H15N4O6Zn·1.5H2O	C17H17N2O7Zn	C28H24N4O6Zn·H2O
  Formula weight	487.75	426.69	595.92
  Crystal system	Monoclinic	Monoclinic	Monoclinic
  Space group	P21/n	P21/n	P21/c
  a/nm	1.187 94(5)	1.026 42(9)	1.198 15(6)
  b/nm	1.180 15(4)	1.753 97(12)	1.630 54(11)
  c/nm	1.499 29(5)	1.045 28(10)	1.414 81(8)
  β/(°)	90.311(3)	111.330(11)	100.294(5)
  Volume/nm3	2.101 89(13)	1.752 9(3)	2.719 5(3)
  Temperature/K	295.2	295.2	295.2
  Z	4	4	4
  Dc/(g·cm-3)	1.570	1.617	1.411
  μ/mm-1	1.211	1.445	0.952
  F(000)	940.0	876.0	1192.0
  θmin, θmax/(°)	3.655, 30.333	4.066, 30.420	3.676, 30.297
  Limiting indices	-16≤h≤16, -16≤k≤16, -21≤l≤20	-14≤h≤14, -24≤k≤24, -14≤l≤13	-16 ≤ h ≤ 16, -22 ≤ k ≤ 20, -19 ≤ l ≤ 19
  Reflection collected, unique	44 158, 5 888	19 114, 4 786	34 674, 7 368
  Data, restraint, parameter	5 888, 6, 273	4 786, 2, 255	7 368, 15, 374
  Goodness-of-fit on F2	0.984	1.034	1.000
  Final R indices [I>2σ(I)]	R1=0.039 3, wR2=0.103 1	R1=0.042 5, wR2=0.105 2	R1=0.051 2, wR2=0.123 2
  Final R indices (all data)	R1=0.054 4, wR2=0.108 4	R1=0.058 7, wR2=0.112 9	R1=0.067 8, wR2=0.131 1
  (Δρ)max, (Δρ)min/(e·nm-3)	670, -460	700, -620	1 110, -570

  CCDC: 2129603, 1; 2129604, 2; 2129604, 3.

  2.   Results and discussion

  2.1   Crystal structure of 1

  Single-crystal X-ray diffraction reveals that complex 1 crystallizes in the monoclinic system with the P2₁/n space group. The asymmetric unit of 1 contains one Zn(Ⅱ) ion, one DTA^2- ion, and half a 1, 2, 4, 5-TIB molecule. Additionally, some disordered guest molecules in the asymmetric unit could not be further identified, so their reflection data have to be subtracted from the corresponding single crystal structure by the SQUEEZE method^[20]. Even so, one and a half guest water molecules should exist in the asymmetric unit according to SQUEEZE information, elemental analysis result, and thermogravimetric data. The Zn(Ⅱ) ion center adopts a slightly distorted tetrahedral configuration to coordinate with two carboxyl oxygen atoms from two DTA^2- ions and two nitrogen atoms from two imidazole groups of 1, 2, 4, 5-TIB molecules (Fig. 1a). If only 1, 2, 4, 5-TIB molecules and Zn(Ⅱ) ions are considered, 1, 2, 4, 5-TIB molecules and Zn(Ⅱ) ion centers build a 2D layer parallel to the crystallographic bc plane (Fig. 1b). Zn(Ⅱ) ion centers are further connected by DTA2- ions, forming a classical pillared-layer framework (Fig. 1c). In the framework, the Zn(Ⅱ) center acts as a four-connected node, while the DTA^2- and 1, 2, 4, 5-TIB ligands are only simple connectors. Therefore, the whole framework can be considered as a four-connected net with a point symbol of (6².8⁴) from a topology view (Fig. 1d)^[21].

  Figure 1

  

  Figure 1.  Crystal structure of 1: (a) coordination environment of Zn(Ⅱ); (b) perspective of 2D 1, 2, 4, 5-TIB-Zn(Ⅱ) layer parallel to the bc plane; (c) 3D pillared-layer framework; (d) 4-connected net

  Ellipsoid probability level: 50%; Symmetry codes: a: 0.5+x, 0.5-y, -0.5+z; b: -0.5+x, 1.5-y, -0.5+z; c: 1-x, 2-y, 1-z

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  2.2   Crystal structure of 2

  Complex ₂ also belongs to the monoclinic space group P2₁/n. The asymmetric unit is comprised of a Zn(Ⅱ) ion, a DTA^2- anion, half a 1, 4-BMIB molecule, and a lattice water molecule. It′s important to note that two carboxyl groups from DTA^2- indicate different coor-dination modes, where one carboxyl group is connected by a Zn(Ⅱ) ion and another carboxyl group is connected by two Zn(Ⅱ) ions. Hence, DTA^2- is a μ₃-linker connected by three Zn(Ⅱ) ions. For such coordination mode in DTA^2-, a binuclear Zn (Zn1, Zn1a) unit Zn₂(CO₂)4 is formed (Fig. 2a). In the unit Zn2(CO₂)₄, Zn(Ⅱ) adopts a five-coordinate geometry of distorted trigonal bipyramid to coordinate with three carboxyl O atoms, an imidazole N atom, and a water molecule. Each Zn₂(CO₂)₄ unit is connected by four DTA^2- ions, resulting in a 2D Zn-DTA layer parallel to the crystallographic ab plane (Fig. 2b). 2D Zn-DTA layers are further connected together by 1, 4-BMIB ligands to form a 3D framework (Fig. 2c). Difference from 1, 2, 4, 5-TIB, 1, 4-BMIB is a slim ligand with low coordination numbers. For this reason, structural interpenetration is difficult to avoid. In fact, the 3D framework of complex 2 is a 2-fold interpenetration structure (Fig. 2d). In complex 2, each Zn₂(CO₂)₄ unit acts as a six-connected node, while DTA^2- and 1, 4-BMIB ligands are simple linkers. Therefore, the whole framework of complex 2 is a six-connected pcu -type net with a point symbol of (4¹².6³) (Fig.S4)^[22].

  Figure 2

  

  Figure 2.  Crystal structure of 2: (a) coordination environment of binuclear unit Zn₂(CO₂)₄; (b) perspective of 2D Zn-DTA layer parallel to ab plane; (c) 3D framework constructed by Zn-DTA layers and 1, 4-BMIB ligands; (d) 2-fold-interpenetrating structure

  Ellipsoid probability level: 50%; Symmetry codes: a: 1-x, 1-y, -z; b: 1.5-x, 0.5+y, 0.5-z; c: 0.5+x, 1.5-y, 0.5+z; d: -x, 1-y, 1-z; e: 1.5-x, -0.5+y, 0.5-z; f: -0.5+x, 1.5-y, -0.5+z

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  2.3   Crystal structure of 3

  Complex 3 crystallizes in the monoclinic system with space group P2₁/c. The corresponding asymmetric unit is composed of one Zn²⁺ ion, two-half DTA^2- ions, and one 1, 4-BMIN molecule. Some disordered guest molecules also exist in complex 3, which also have been disposed of by the SQUEEZE method^[21]. Based on the SQUEEZE information, elemental analysis result, and thermogravimetric data, each asymmetric unit in complex 3 should contain a disordered guest water molecule. Just as Zn(Ⅱ) ion in complex 1, the Zn(Ⅱ) ion is still a slightly distorted {ZnO₂N₂} tetrahedral sphere, surrounded by two carboxylate O atoms from two DTA^2- anions and two N atoms from two 1, 4-BMIN molecules (Fig. 3a). DTA^2- and 1, 4-BMIN ligands connect the Zn(Ⅱ) ion centers together to obtain a 3D framework (Fig. 3b), which is a triple-interleaved dia-type network with a point symbol of (6⁶) (Fig. 3c and 3d)^[22].

  Figure 3

  

  Figure 3.  Crystal structure of 3: (a) coordination environment of Zn(Ⅱ); (b) 3D framework; (c) 3-fold-interpenetrating structure; (d) 4-connected dia net

  Ellipsoid probability level: 50%; Symmetry codes: a: 1+x, 1.5-y, 0.5+z; b: -x, 1-y, 1-z; c: 1-x, 1-y, -z

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  2.4   PXRD patterns and TGA

  The PXRD of 1-3 was performed at room temperature to check their phase purity. As shown in Fig. 4a, the test PXRD patterns match well with the simulated ones, indicating the phase purity of complexes 1, 2, and 3 (Fig. 4a). To further investigate their thermal stabilities, the TGA experiments for 1-3 were carried out from room temperature to 800 ℃ under a nitrogen atmosphere (Fig. 4b). The TGA curve of 1 indicated the first weight loss of 6.0% from room temperature to 110 ℃, which should be attributed to the release of one and a half disorder water molecules in each asymmetric unit (Calcd. 5.6%). After 300 ℃, rapid weight loss continued until the end of the experiment. Complex 2 indicated an about 4.5% weight loss from the beginning to 120 ℃, which mainly corresponds to the loss of coordination water molecules (Calcd. 4.2%). The curve between 120 and 379 ℃ was almost a straight line, revealing that complex 2 is very stable in this temperature range. After 379 ℃, the TGA curve droped sharply until the end of the experiment. Complex 3 displayed a 3.1% weight loss before 120 ℃, confirming that each asymmetric unit contains a guest water molecule (Calcd. 3.0%). As the temperature further increased, the framework began to collapse from 320 ℃.

  Figure 4

  

  Figure 4.  PXRD patterns (a) and TGA curves (b) of complexes 1-3

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  2.5   UV-Vis and luminescent properties

  The solid UV-Vis absorption spectra of complexes 1-3 are shown in Fig. 5a. In the UV region between 200 and 400 nm, all complexes had two maximum absorption peaks at 260 and 325 nm, respectively. These characteristic absorption peaks should be attributed to the π-π* transition between the ligands and metal ions^[23].

  Figure 5

  

  Figure 5.  Solid UV-Vis absorption spectra of complexes 1-3 (a) and fluorescent emission spectra (b) of 1-3 and H₂DTA

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  Considering d¹⁰ metal inorganic-organic hybrid coordination polymers with excellent luminescent properties, their fluorescence tests were performed (Fig. 5b). Under the excitation light with a wavelength of 275 nm, H₂DTA had a maximum emission peak at 410 nm. In contrast, the emission bands of the three complexes were stronger than that of the ligand, and the maximum emission peaks for complexes 1-3 were 398 nm (λ_ex=340 nm), 385 nm (λ_ex=328 nm), and 393 nm (λ_ex=281 nm), respectively. Compared to the emission peak of H₂DTA, all complexes had a blue shift phenomenon, which may be caused by the intraligand (n-π* or π-π*) transition. The enhanced luminescence of complexes 1-3 should be attributed to the combination of the ligand and the metal center, reducing the energy loss caused by non-radiation attenuation^[24].

  3.   Conclusions

  In summary, different imidazole derivatives as linkers were introduced to assemble with Zn(Ⅱ) ions to obtain three 3D MOFs. Complexes 1, 2, and 3 are a four-connected net, a six-connected pcu-type net with a 2-fold interpenetration structure, and a triple-interleaved dia-type network, respectively. The rigid imidazole derivatives play a key role in constructing complexes with different structures. Moreover, compared with the fluorescence of H₂DTA, the fluorescence of the three complexes was enhanced and the blue shift occurred.

  Supporting information is available at http://www.wjhxxb.cn

  
  
• 1. [1]

     Zhan D Y, Saeed A, Li Z X, Wang C M, Yu Z W, Wang J F, Zhao N J, Xu W H, Liu J H. Highly Fluorescent Scandium-Tetracarboxylate Frameworks: Selective Detection of Nitro-Aromatic Compounds, Sensing Mechanism, and Their Application[J]. Dalton Trans., 2020, 49(48):  17737-17744. doi: 10.1039/D0DT03781H

  2. [2]

     Gao M L, Cao X M, Zhang Y Y, Qi M H, Wang S M, Liu L, Han Z B. A Bifunctional Luminescent Europium-Organic Framework for Highly Selective Sensing of Nitrobenzene and 4-Aminophenol[J]. RSC Adv., 2017, 7(71):  45029-45033. doi: 10.1039/C7RA08885J

  3. [3]

     Hu Z C, Pramanik S, Tan K, Zheng C, Liu W, Zhang X, Chabal Y J, Li J. Selective, Sensitive, and Reversible Detection of Vapor-Phase High Explosives via Two-Dimensional Mapping: A New Strategy for MOF Based Sensors[J]. Cryst Growth Des., 2013, 13(10):  4204-4207. doi: 10.1021/cg4012185

  4. [4]

     Kaur R, Paul A, Deep A. Highly Sensitive Chemosensing of Trinitrotoluene with Europium Organic Framework/Gold Nanoparticle Composite[J]. Inorg. Chem. Commun., 2014, 43:  118-120. doi: 10.1016/j.inoche.2014.02.025

  5. [5]

     Roales J, Moscoso F G, Gámez F, Lopes-Costa T, Sousaraei A, Casado S, Castro-Smirnov J R, Cabanillas-Gonzalez J, Almeida J, Queirós C, Cunha-Silva L, Silva A M G, Pedrosa J M. Preparation of Luminescent Metal-Organic Framework Films by Soft-Imprinting for 2, 4-Dinitrotoluene Sensing[J]. Materials, 2017, 10(9):  992. doi: 10.3390/ma10090992

  6. [6]

     Wu Y, Li Y L, Wu X R, Luo M M, Zou L K, Xu Q X, Cai S G. An Uncommon 3D (3, 8)-Connected Metal-Organic Framework: Luminescence Sensing and Photocatalytic Properties[J]. J. Solid State Chem., 2018, 262:  256-263. doi: 10.1016/j.jssc.2018.03.031

  7. [7]

     Du Z Q, Li Y P, Wang X X, Wang J, Zhai Q G. Enhanced Electrochemical Performance of Li-Co-BTC Ternary Metal-Organic Frameworks as Cathode Materials for Lithium-Ion Batteries[J]. Dalton Trans., 2019, 48(6):  2013-2018. doi: 10.1039/C8DT04863K

  8. [8]

     Qu X L, Gui D, Zheng X L, Li R, Han H L, Li X, Li P Z. A Cd-Based Metal-Organic Framework as a Luminance Sensor to Nitrobenzene and Tb(Ⅲ) Ion[J]. Dalton Trans., 2016, 45(16):  6983-6989. doi: 10.1039/C6DT00162A

  9. [9]

     Sowmehesaraee M S, Ranjbar M, Abedi M, Mozaffari S A. Fabrication of Lead Iodide Perovskite Solar Cells by Incorporating Zirconium, Indium and Zinc Metal-Organic Frameworks[J]. Sol. Energy, 2021, 214:  138-148. doi: 10.1016/j.solener.2020.12.001

  10. [10]

      Goswami R, Seal N, Dash S R, Tyagi A, Neogi S. Devising Chemically Robust and Cationic Ni(Ⅱ)-MOF with Nitrogen-Rich Micropores for Moisture-Tolerant CO₂ Capture: Highly Regenerative and Ultrafast Colorimetric Sensor for TNP and Multiple Oxo-Anions in Water with Theoretical Revelation[J]. ACS Appl. Mater. Interfaces, 2019, 11(43):  40134-40150. doi: 10.1021/acsami.9b15179

  11. [11]

      Mohanty A, Singh U P, Butcher R J, Das N, Roy P. Synthesis of Fluorescent MOFs: Live-Cell Imaging and Sensing of a Herbicide[J]. CrystEngComm, 2020, 22(26):  4468-4477. doi: 10.1039/D0CE00490A

  12. [12]

      Shi Z Q, Ji N N, Hu H L. Luminescent Triphenylamine-Based Metal-Organic Frameworks: Recent Advances in Nitroaromatics Detection[J]. Dalton Trans., 2020, 49(37):  12929-12939. doi: 10.1039/D0DT02213F

  13. [13]

      Gheorghe A, Imaz I, Vlugt J I V D, Maspoch D, Tanase S. Tuning the Supramolecular Isomerism of MOF-74 by Controlling the Synthesis Conditions[J]. Dalton Trans., 2019, 48(27):  10043-10050. doi: 10.1039/C9DT01572H

  14. [14]

      Li J, Zhao Z X, Liu T, Gong Z F, Jin Y H, Sun L B, Qi M. Cu(Ⅱ)-Based Coordination Polymers: Protective Effect on Suppurative Lymphadenitis by Regulating miR-155 and miR -34a Expression in the Lymph Node Cells[J]. J. Coord. Chem., 2021, 74(9):  1673-1682.

  15. [15]

      Wang Y, Zeng H M, Mao W T, Wang X J, Jiang Z G, Zhan C H, Feng Y L. The Synthesis and Photoluminescence of Three Porous Metal-Organic Frameworks[J]. Inorg. Chem. Commun., 2021, 129:  108613. doi: 10.1016/j.inoche.2021.108613

  16. [16]

      Böhle T, Eissmann F, Weber E, Mertens F O R L. Poly[(μ₄-2, 5-dimethoxybenzene-1, 4-dicarboxylato)manganese(Ⅱ)] and Its Zinc(Ⅱ) Analogue: Three-Dimensional Coordination Polymers Containing Unusually Coordinated Metal Centres[J]. Acta Crystallogr. Sect. C, 2011, C67:  5-8.

  17. [17]

      Guo Z G, Reddy M V, Goh B M, San A K P, Bao Q, Loh K P. Electrochemical Performance of Graphene and Copper Oxide Composites Synthesized from a Metal-Organic Framework (Cu-MOF)[J]. RSC Adv., 2013, 3(41):  19051-19056. doi: 10.1039/c3ra43308k

  18. [18]

      Dolomanov O V, Bourhis L J, Gildea R J, Howard J A K, Puschmann H. OLEX2: A Complete Structure Solution, Refinement and Analysis Program[J]. J. Appl. Crystallogr., 2009, 42:  339-341. doi: 10.1107/S0021889808042726

  19. [19]

      Sheldrick G M. Crystal Structure Refinement with SHELXL[J]. Acta Crystallogr. Sect. C, 2015, C71:  3-8.

  20. [20]

      Spek A L. PLATON SQUEEZE: A Tool for the Calculation of the Disordered Solvent Contribution to the Calculated Structure Factors[J]. Acta Crystallogr. Sect. C, 2015, C71:  9-18.

  21. [21]

      Aexandrov E V, Blatov V A, Kochetkov A V, Proserpio D M. Underlying Nets in Three-Periodic Coordination Polymers: Topology, Taxonomy and Prediction from a Computer-Aided Analysis of the Cambridge Structural Database[J]. CrystEngComm, 2011, 13(12):  3947-3958. doi: 10.1039/c0ce00636j

  22. [22]

      Cui Y, Yue Y, Qian G, Cheng B L. Luminescent Functional Metal-Organic Frameworks[J]. Chem. Rev., 2012, 112(2):  1126-1162. doi: 10.1021/cr200101d

  23. [23]

      唐龙, 付宇豪, 王一彤, 王欢欢, 王记江, 侯向阳, 王潇. 利用2, 2'-氧基双(苯甲酸)和含N配体构筑的三个配合物的合成、结构与荧光性能[J]. 无机化学学报, 2020,36,(8): 1550-1556. TANG L, FU Y H, WANG Y T, WANG H H, WANG J J, HOU X Y, WANG X. Three Complexes Constructed Using 2, 2′ -Oxybis(benzoic acid) and N-Donor Ligands: Syntheses, Structures and Fluorescent Properties[J]. Chinese J. Inorg. Chem., 2020, 36(8):  1550-1556.

  24. [24]

      黎彧, 曾福燃, 周峰, 李善吉. 由醚氧桥联羧酸配体构筑的铜(Ⅱ)、锌(Ⅱ)和锰(Ⅱ)配位聚合物的合成、晶体结构、荧光及光催化性质[J]. 无机化学学报, 2020,36,(11): 2124-2134. doi: 10.11862/CJIC.2020.243LI Y, ZENG F R, ZHOU F, LI S J. Syntheses, Crystal Structures, Luminescence and Photocatalytic Activity of Cu(Ⅱ), Zn(Ⅱ) and Mn(Ⅱ) Coordination Polymers Based on Ether-Bridged Carboxylic Acids[J]. Chinese J. Inorg. Chem., 2020, 36(11):  2124-2134. doi: 10.11862/CJIC.2020.243

• 

  Scheme 1  Structures of H₂DTA, 1, 3, 4, 5-TIB, 1, 4-BMIB, and 1, 4-BMIN

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  Figure 1  Crystal structure of 1: (a) coordination environment of Zn(Ⅱ); (b) perspective of 2D 1, 2, 4, 5-TIB-Zn(Ⅱ) layer parallel to the bc plane; (c) 3D pillared-layer framework; (d) 4-connected net

  Ellipsoid probability level: 50%; Symmetry codes: a: 0.5+x, 0.5-y, -0.5+z; b: -0.5+x, 1.5-y, -0.5+z; c: 1-x, 2-y, 1-z

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  Figure 2  Crystal structure of 2: (a) coordination environment of binuclear unit Zn₂(CO₂)₄; (b) perspective of 2D Zn-DTA layer parallel to ab plane; (c) 3D framework constructed by Zn-DTA layers and 1, 4-BMIB ligands; (d) 2-fold-interpenetrating structure

  Ellipsoid probability level: 50%; Symmetry codes: a: 1-x, 1-y, -z; b: 1.5-x, 0.5+y, 0.5-z; c: 0.5+x, 1.5-y, 0.5+z; d: -x, 1-y, 1-z; e: 1.5-x, -0.5+y, 0.5-z; f: -0.5+x, 1.5-y, -0.5+z

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  Figure 3  Crystal structure of 3: (a) coordination environment of Zn(Ⅱ); (b) 3D framework; (c) 3-fold-interpenetrating structure; (d) 4-connected dia net

  Ellipsoid probability level: 50%; Symmetry codes: a: 1+x, 1.5-y, 0.5+z; b: -x, 1-y, 1-z; c: 1-x, 1-y, -z

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  Figure 4  PXRD patterns (a) and TGA curves (b) of complexes 1-3

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  Figure 5  Solid UV-Vis absorption spectra of complexes 1-3 (a) and fluorescent emission spectra (b) of 1-3 and H₂DTA

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  Table 1.  Crystallographic data and refinement parameters for MOFs 1-3

  Parameter	1	2	3
  Empirical formula	C19H15N4O6Zn·1.5H2O	C17H17N2O7Zn	C28H24N4O6Zn·H2O
  Formula weight	487.75	426.69	595.92
  Crystal system	Monoclinic	Monoclinic	Monoclinic
  Space group	P21/n	P21/n	P21/c
  a/nm	1.187 94(5)	1.026 42(9)	1.198 15(6)
  b/nm	1.180 15(4)	1.753 97(12)	1.630 54(11)
  c/nm	1.499 29(5)	1.045 28(10)	1.414 81(8)
  β/(°)	90.311(3)	111.330(11)	100.294(5)
  Volume/nm3	2.101 89(13)	1.752 9(3)	2.719 5(3)
  Temperature/K	295.2	295.2	295.2
  Z	4	4	4
  Dc/(g·cm-3)	1.570	1.617	1.411
  μ/mm-1	1.211	1.445	0.952
  F(000)	940.0	876.0	1192.0
  θmin, θmax/(°)	3.655, 30.333	4.066, 30.420	3.676, 30.297
  Limiting indices	-16≤h≤16, -16≤k≤16, -21≤l≤20	-14≤h≤14, -24≤k≤24, -14≤l≤13	-16 ≤ h ≤ 16, -22 ≤ k ≤ 20, -19 ≤ l ≤ 19
  Reflection collected, unique	44 158, 5 888	19 114, 4 786	34 674, 7 368
  Data, restraint, parameter	5 888, 6, 273	4 786, 2, 255	7 368, 15, 374
  Goodness-of-fit on F2	0.984	1.034	1.000
  Final R indices [I>2σ(I)]	R1=0.039 3, wR2=0.103 1	R1=0.042 5, wR2=0.105 2	R1=0.051 2, wR2=0.123 2
  Final R indices (all data)	R1=0.054 4, wR2=0.108 4	R1=0.058 7, wR2=0.112 9	R1=0.067 8, wR2=0.131 1
  (Δρ)max, (Δρ)min/(e·nm-3)	670, -460	700, -620	1 110, -570

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