English

• 0.   Introduction

  As a type of hybrid material, coordination polymers (CPs) are constructed by alternating arrangements of organic linkers and metal clusters/ions. The rich choices both in the organic linkers and the metal clusters/ions lead to the diversity of CPs, which has attracted much attention from researchers to study CPs′ applications, such as photoluminescence property, magnetism, catalysis, adsorption, separation, and more^[1-7]. Generally speaking, the starting materials of CP synthesis are crucial for the final structure and properties. Thus, it is important to choose the organic ligands and metal ions. As we all know, organic ligands are mainly divided into rigid and flexible ones. When some simple ligands are used, especially for rigid ligands, it is easy to predict the final structure of CPs. In contrast to rigid ligands with single conformation, it is more difficult to predict the final structures of flexible ligands. Because flexible ligands can exhibit different kinds of conformation when they coordinate with metal ions^[8-11]. However, the conformation diversity of flexible ligands provides a method for preparing CPs with novel structures, especially some structures that cannot be obtained through rigid ligands^[12-14]. For example, both 3, 3′, 5, 5′-biphenyltetracarboxlic acid (H₄DPTC) and 5-(3, 5-dicarboxybenzyloxy)isophthalic acid (H₄DBIP) all can act as ligand^[15-17]. In H₄DPTC, two benzene rings are usually coplanar. Compared with H₄DPTC, when H₄DBIP was used as a ligand, two benzene rings can be coplanar or perpendicular. Thus, H₄DBIP can be a plane or tetrahedron, which leads to multiple topology structures, such as dia, flu, pts, lon, msw, and nbo.

  Because of the influence on CPs′ structures and properties, the research of inter-molecular non-covalent interactions is an important part of the crystal engineering of CPs. Inter-molecular non-covalent interactions contain many types, such as van der Waals forces, hydrogen bonding, π…π stacking interactions^[18-20]. Among them, hydrogen bonding research is most important because the force is strong and directional, which often determines the fashion of molecular structure and packing in the solid state^[21-23]. We have recently synthesized various CPs based on a series of flexible dicarboxylate ligands and have discussed inter-molecular non-covalent interactions ^[24-25]. Based on our previous works, in this article, we choose 2, 2′-(1, 2-phenylenebis(methylene))bis(sulfanediyl)dinicotinic acid (H₂L) and 1, 10-phenanthroline (phen) as ligands. Six CPs have been synthesized and their formulas are [Mn(L)(phen)(H₂O)]_n (1), [Co(L)(phen)(H₂O)]_n (2), [Cu(L)(phen)(H₂O)]_n (3), [Zn₂(L)₂(phen)₂(H₂O)]_n (4), [Zn(L)(phen)]_n (5), and [Cd(L)(phen)₂]_n (6). Single-crystal X-ray diffraction analysis revealed that the structures of 1-6 are 1D chains. Among them, 1 and 2 have the same structure from macrocycle to 1D chain. There are two conformations of L^2- ligand with syn-conformation in 1 and 2, while anti-conformation in 3-6. Hydrogen bonding interactions further connect the 1D chains to form 3D supramolecular structures. In addition, the thermal stability and photoluminescence properties were investigated.

  1.   Experimental

  1.1   Materials and methods

  The ligand H₂L was synthesized according to the reported procedure^[26-27] and other chemicals and solvents were commercially available of reagent grade. Elemental analysis for C, H, N, and S was performed on a Perkin-Elmer 240 C Elemental Analyzer. FTIR spectra were recorded in a range of 400-4 000 cm^-1 on a Nicolet IS50 FT-IR spectrophotometer using KBr pellets. At room temperature, powder X-ray diffraction (PXRD) measurements were performed on a Bruker D8 Advance X-ray diffractometer using Cu Kα radiation (λ=0.154 18 nm) with the 2θ range from 5° to 50°, in which the X-ray tube was operated at 40 kV and 40 mA. Thermogravimetric analysis (TGA) was performed on a simultaneous Netzsch STA449 F5 Jupiter thermal analyzer under N₂ with a heating rate of 10 ℃·min^-1 from 30 to 800 ℃. The photoluminescence spectrum was measured on Edinburgh FLS980 Series of fluorescence spectrometers.

  1.2   Synthesis of complexes 1-6

  1.2.1   Synthesis of complex 1

  A mixture of H₂L (20.6 mg, 0.05 mmol), phen (9.0 mg, 0.05 mmol), and MnSO₄·H₂O (16.9 mg, 0.10 mmol) in DMF/H₂O (1∶1, V/V, 10.0 mL) was sealed in a 20.0 mL bottle and heated at 90 ℃ for three days. After cooling to room temperature, yellow block-shaped crystals of complex 1 were obtained. The yield of the crystals was 51%. Anal. Calcd. for C₃₂H₂₄N₄O₅S₂Mn(%): C, 57.92; H, 3.65; N, 8.44; S, 9.66. Found(%): C, 57.67; H, 3.95; N, 8.31; S, 9.78. IR (KBr, cm^-1): 1 670 (m), 1 591 (s), 1 536 (m), 1 455 (w), 1 423 (m), 1 376 (s), 1 310 (w), 1 256 (m), 1 147 (w), 1 104 (w), 1 060 (w), 1 037 (m), 848 (m), 783 (w), 728 (s), 695 (w), 652 (w), 602(w), 553 (w) (Fig.S1, Supporting information).

  1.2.2   Synthesis of complex 2

  The synthesis of complex 2 was similar to 1 except that CoCl₂·6H₂O (16.9 mg, 0.10 mmol) was added instead of MnSO₄·H₂O. The resultant mixture was sealed in a 20.0 mL bottle and heated at 90 ℃ for three days. After cooling to room temperature, red block-shaped crystals of 2 were obtained. The yield of the crystals was 35%. Anal. Calcd. for C₃₂H₂₄N₄O₅S₂Co(%): C, 57.57; H, 3.62; N, 8.39; S, 9.60. Found(%): C, 57.72; H, 3.91; N, 8.23; S, 9.46. IR (KBr, cm^-1): 1 675 (m), 1 609 (s), 1 530 (m), 1 483 (w), 1 366 (w), 1 316 (s), 1 253 (w), 1 123 (w), 1 060 (m), 965 (m), 931 (w), 831 (w), 788 (m), 743 (w), 695 (w), 654 (m), 540 (w) (Fig.S1).

  1.2.3   Synthesis of complex 3

  The synthesis of complex 3 was similar to 1 and 2 except that metal salt was replaced with CuCl₂·2H₂O (17.0 mg, 0.10 mmol). After cooling to room temperature, blue block-shaped crystals of 3 were obtained. The yield of the crystals was 46%. Anal. Calcd. for C₃₂H₂₄N₄O₅S₂Cu(%): C, 57.17; H, 3.60; N, 8.33; S, 9.54. Found(%): C, 57.01; H, 3.95; N, 8.31; S, 9.66. IR (KBr, cm^-1): 1 678 (s), 1 596 (s), 1 510 (w), 1 460 (m), 1 429 (w), 1 362(s), 1 313 (w), 1 274 (w), 1 254 (s), 1 194 (w), 1 149 (w), 1 109 (w), 1 061 (m), 1 046 (w), 854 (s), 810 (w), 755 (m), 723 (m), 700 (w), 654 (w) (Fig.S1).

  1.2.4   Synthesis of complex 4

  The synthesis of complex 4 was similar to 1-3 except that metal salt was replaced with ZnCl₂·2H₂O (13.6 mg, 0.10 mmol). After cooling to room temperature, colorless block-shaped crystals of 4 were obtained. The yield of the crystals was 56%. Anal. Calcd. for C₆₄H₄₆N₈O₉S₄Zn₂(%): C, 57.79; H, 3.49; N, 8.42; S, 9.64. Found(%): C, 57.82; H, 3.25; N, 8.58; S, 9.45. IR (KBr, cm^-1): 1 684 (m), 1 655 (w), 1 596 (s), 1 530 (m), 1 399 (s), 1 312 (w), 1 257 (s), 1 161 (m), 1 102 (w), 1 008 (w), 880 (w), 776 (m), 696 (w), 654 (w), 621 (w), 550 (w), 504 (w) (Fig.S1).

  1.2.5   Synthesis of complex 5

  The synthesis of complex 5 was similar to 1-4 except that metal salt was replaced with ZnSO₄·7H₂O (28.7 mg, 0.10 mmol). After cooling to room temperature, colorless block-shaped crystals of 5 were obtained. Anal. Calcd. for C₃₂H₂₂N₄O₄S₂Zn(%): C, 58, 58; H, 3.38; N, 8.54; S, 9.77. Found(%): C, 58.32; H, 3.71; N, 8.78; S, 10.02. IR (KBr, cm^-1): 1 633 (m), 1 612 (s), 1 583 (m), 1 518 (w), 1 446 (w), 1 427 (w), 1 384 (s), 1 352 (m), 1 240 (w), 1 157 (w), 1 123 (w), 1 104 (w), 1 070 (m), 847 (m), 773 (s), 725 (w), 651 (w) (Fig.S1).

  1.2.6   Synthesis of complex 6

  The synthesis of complex 6 was similar to 1-5 except that metal salt was replaced with CdCl₂·2H₂O (22.8 mg, 0.10 mmol). After cooling to room temperature, colorless block-shaped crystals of 6 were obtained. The yield of the crystals was 42%. Anal. Calcd. for C₄₄H₃₀N₆O₄S₂Cd(%): C, 59.83; H, 3.42; N, 9.51; S, 7.26. Found(%): C, 58.03; H, 3.76; N, 9.12; S, 7.45. IR (KBr, cm^-1): 1 675 (w), 1 589 (m), 1 568 (s), 1 542 (m), 1 514 (w), 1 427 (w), 1 374 (s), 1 279 (w), 1 254 (w), 1 144 (w), 1 100 (w), 1 061 (m), 1 042 (w), 849 (m), 811 (s), 773 (w), 726 (s), 698 (w), 655 (w), 564 (w) (Fig.S1).

  1.3   Crystallographic data collection and refinement

  Diffraction data for complexes 1-3 and 5 were collected on a Bruker D8 VENTURE, while the data for 4 and 6 were collected on Bruker APEX-Ⅱ CCD. They were all graphite monochromated Mo Kα radiation sources (λ=0.071 073 nm) in φ-ω scan mode. Multi-scan absorption corrections of 1-6 were applied by using the program SADABS. The SAINT program was used for the integration of diffraction data and the intensity correction for Lorentz and polarization effects. By direct methods, the structures of 1-6 were solved. All non-hydrogen atoms were refined anisotropically on F² by the full-matrix least-squares technique using the SHELXL crystallographic software package. Except for water molecules, hydrogen atoms were generated geometrically and the riding model was used to refine isotropically. For the hydrogen atoms of water molecules, they were found directly. The details of the crystal parameters, data collection, and refinements are summarized in Table 1. Selected bond lengths and angles for 1-6 are listed in Table S1. The parameters of hydrogen bonds for 1-6 are listed in Table S2.

  Table 1

  

  Table 1.  Crystal data and structure refinements for complexes 1-6

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  Parameter	1	2	3	4	5	6
  Formula	C32H24N4O5S2Mn	C32H24N4O5S2Co	C32H24N4O5S2Cu	C64H46N8O9S4Zn2	C32H22N4O4S2Zn	C44H30N6O4S2Cd
  Formula weight	663.61	667.60	672.21	1 330.07	656.02	883.26
  Crystal system	Triclinic	Triclinic	Triclinic	Triclinic	Triclinic	Orthorhombic
  Space group	P1	P1	P1	P1	P1	Pna21
  a / nm	0.836 19(7)	0.854 6(3)	0.883 47(8)	1.128 42(5)	0.973 89(4)	2.917 77(11)
  b / nm	1.138 23(11)	1.128 8(3)	1.086 31(11)	1.247 33(5)	1.171 90(4)	1.174 31(6)
  c / nm	1.577 27(14)	1.554 9(4)	1.597 12(17)	2.095 95(10)	1.268 70(4)	1.077 93(4)
  α / (°)	92.305(3)	90.994(8)	87.998(4)	93.857 0(10)	80.172 0(10)
  β / (°)	95.826(2)	96.682(10)	79.674(4)	103.215(2)	89.364 0(10)
  γ / (°)	108.812(2)	108.900(9)	69.086(4)	90.488(2)	87.259 0(10)
  V / nm3	1.409 4(2)	1.407 0(6)	1.407 9(2)	2.864 6(2)	1.425 08(9)	3.693 4(3)
  Z	2	2	2	2	2	4
  Dc / (g·cm-3)	1.564	1.576	1.586	1.542	1.529	1.588
  μ / mm-1	0.668	0.810	0.976	1.052	1.055	0.760
  F(000)	682	686	690	1 364	672	1 792
  Unique reflection	6 401	6 410	6 417	10 217	6 518	7 029
  Observed reflection [I > 2σ(I)]	4 451	4 993	3 475	13 071	4 607	8 082
  Number of parameters	400	419	400	785	388	514
  GOF	1.043	1.043	1.052	0.948	1.016	1.072
  Final R indices [I > 2σ(I)]*	R1=0.061 3, wR2=0.114 5	R1=0.048 1, wR2=0.092 9	R1=0.087 5, wR2=0.187 8	R1=0.046 3, wR2=0.135 7	R1=0.049 5, wR2=0.095 5	R1=0.039 3, wR2=0.069 1
  R indices (all data)	R1=0.099 7, wR2=0.135 2	R1=0.070 8, wR2=0.105 2	R1=0.175 8, wR2=0.238 2	R1=0.063 6, wR2=0.152 8	R1=0.084 1, wR2=0.110 4	R1=0.056 4, wR2=0.076 9
  *R1=∑||Fo|-|Fc||/∑|Fo|, wR2=[∑w(Fo2-Fc2)2/∑w(Fo2)2]1/2.

  2.   Results and discussion

  2.1   Crystal structures of complexes 1-6

  2.1.1   Crystal structures of complexes 1 and 2

  Crystallographic analysis indicates that complexes 1 and 2 crystallize in the triclinic P1 space group and are isomorphic. Here the following structural description will focus on 1. In 1, the coordination number of Mn(Ⅱ) is six and the coordination geometry of Mn(Ⅱ) is a distorted octahedron. Among them, N3, N4, O1^ⅱ, and O5 form an equatorial plane, while O1^ⅰ and O4 are in the axial direction (Fig. 1a and S2a). Two Mn(Ⅱ) ions are connected by two L^2- to generate a rectangular macrocycle with a maximum separation of 1.617 nm, while the coordinated phen ligands fill in the macrocycle. At the same time, each O1 links two Mn(Ⅱ). Thus, the bridging O1 links adjacent rings into a 1D chain (Fig. 1b). Between coordinated water molecules and O3 of the carboxylate group, there are intermolecular hydrogen bonding interactions. The 1D chains are further linked together by O5—H5A…O3 hydrogen bonding interactions to form a 2D layer (Fig. 1c and S2b). The adjacent layers by the weak H-bonding C28—H28…N1 can be formed into a 3D framework (Fig. 1d).

  Figure 1

  

  Figure 1.  (a) Coordination environment of Mn(Ⅱ) in complex 1 with 50% thermal ellipsoid probability (hydrogen atoms have been omitted for clarity); (b) 1D chain in 1; (c) Hydrogen bonding interactions between two 1D chains in 1 indicated by blue dashed lines; (d) 3D framework structure of 1 based on chains with short contact indicated by dashed lines (blue: O5—H5A…O3; black: C28—H28…N1)

  Symmetry codes: ^ⅰ 1-x, 1-y, 1-z; ^ⅱ-1+x, -1+y, z.

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  2.1.2   Crystal structure of complex 3

  Crystallographic analysis indicates that the asymmetric unit of complex 3 consists of one Cu(Ⅱ) ion, one L^2- ligand, one phen ligand, and one coordinated H₂O molecule. The coordination number of Cu(Ⅱ) is five. Each Cu(Ⅱ) is coordinated by two N atoms and three O atoms with distorted square pyramidal geometry. Among them, N1 and N2 come from the phen ligand, while O1 and O4^ⅰ come from the L^2- ligand and O5 comes from coordinated H₂O molecule (Fig. 2a). Each Cu(Ⅱ) links two L^2- ligands and each L^2- ligand connects two Cu(Ⅱ). Thus, the adjacent Cu(Ⅱ) and L^2- link together to form a 1D chain (Fig. 2b). Like 1, there are also intermolecular hydrogen bonding interactions in 3. By intermolecular H-bonding interaction O5—H5A…O3, the adjacent two chains link together (Fig. 2c and Fig.S3a). Through the weak H-bonding interactions, C1—H1…O3, C8—H8…O3, C10—H10…O2 and C1—H1…O4 further link the chains to formed 2D layer (Fig.S3b). The layers can be further extended into 3D supramolecular architecture by C17—H17…N4 (Fig. 2d).

  Figure 2

  

  Figure 2.  (a) Coordination environment of Cu(Ⅱ) in complex 3 with 50% thermal ellipsoid probability (hydrogen atoms have been omitted for clarity; (b) 1D chain in 3; (c) Hydrogen bonding interactions between two chains in 3 indicated by black dashed lines; (d) 3D framework of 3 based on chains with short contact indicated by dashed lines (black: O5—H5A…O3; pink: C1—H1…O3; yellow: C8—H8…O3; bright green: C10—H10…O2; blue: C1—H1…O4; orange: C17—H17…N4)

  Symmetry code: ^ⅰ 1+x, -1+y, z.

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  2.1.3   Crystal structure of complex 4

  In complex 4, the asymmetric unit consists of two Zn(Ⅱ) ions, two L^2- ligands, two phen ligands, and one coordinated H₂O molecule. Zn1 and Zn2 have the same coordination number of five. Zn1 is coordinated with two N atoms from one phen ligand and three O atoms from two L^2- ligands, while Zn2 is coordinated with two N atoms from one phen ligand, two O atoms from two L^2- ligands and one O atom from coordinated H₂O molecule. Interestingly, Zn1 and Zn2 are linked together by L^2- ligands to form two 1D chains separately, which are further joined together by O9—H9C…O4 and O9—H9D…O2 to generate a double-chain structure (Fig. 3b). The double-chains further link together by the weak H-bonding interaction C61—H61…O8, C25—H25…O5, and C50—H50…O8 to form a 2D layer, which further joined by C9—H9A…S2 to generate a 3D framework (Fig. 3c and S4).

  Figure 3

  

  Figure 3.  (a) Coordination environment of Zn(Ⅱ) in complex 4 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chains in 4 with hydrogen bonding interactions indicated by dashed lines (red: based on Zn1; green: based on Zn2; black: O9—H9C…O4; yellow: O9—H9D…O2); (c) 3D framework of 4 based on chains with short contact indicated by dashed lines (black: O9—H9C…O4; yellow: O9—H9D…O2; pink: C61—H61…O8; bright green: C25—H25…O5; blue: C50—H50…O8; purple: C9—H9A…S2)

  Symmetry code: ^ⅰ x, -1+y, z.

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  2.1.4   Crystal structure of complex 5

  In complex 5, the coordination number of Zn(Ⅱ) is five. The coordination environment of Zn(Ⅱ) is similar to Zn1 in 4 with two N atoms from one phen ligand and three O atoms from two L^2- ligands (Fig. 4a). Thus, each Zn(Ⅱ) ion connects two L^2- ligands to form a 1D chain (Fig. 4b). Different from 1-4, no strong intermolecular H-bonding interactions exist in 5. Instead, there are weak intermolecular H-bonding interactions between adjacent 1D chains and the distance of H…A is greater than 0.25 nm (Fig. 4c and Fig.S5).

  Figure 4

  

  Figure 4.  (a) Coordination environment of Zn(Ⅱ) in complex 5 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chain in 5 (red: L^2- ligands and green: phen ligands); (c) Hydrogen bonding interactions between adjacent 1D chains in 5 indicated by black dashed lines (blue: C10—H10…O1; black: C29—H29…O4; turquoise: C16—H16…O2; yellow: C3—H3…O3)

  Symmetry code: ^ⅰ x, y, 1+z.

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  2.1.5   Crystal structure of complex 6

  Crystallographic analysis indicates that complex 6 crystallizes in the orthorhombic Pna2₁ space group. The coordination number of Cd(Ⅱ) is six. As shown in Fig. 5a, four N atoms from two phen ligands and two O atoms from two L^2- ligands coordinate with Cd(Ⅱ). Each Cd(Ⅱ) ion connects two L^2- ligands to form a 1D chain (Fig. 5b). Such as in 5, there are weak intermolecular H-bonding interactions between the adjacent chains, which are further extended into a 3D supramolecular architecture (Fig. 5c and Fig.S6).

  Figure 5

  

  Figure 5.  (a) Coordination environment of Cd(Ⅱ) in complex 6 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chain in 6 (red: L^2- ligands and green: phen ligands); (c) 3D structure of 6 with hydrogen bonds indicated by dashed lines (different colors for different chains)

  Symmetry code: ^ⅰ-0.5+x, 0.5-y, z.

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  2.2   Synthesis and comparison of the complexes

  Complexes 1-6 were synthesized and characterized based on the flexible dicarboxylate ligand L^2-. The synthetic conditions are the same except for different metal salts. Among them, 4 and 5 differ only in anions. The synthetic raw material of 1 was replaced by MnCl₂, the structure is the same. Similarly, the synthetic raw materials of 2 and 6 were replaced by corresponding sulfates, no crystals were obtained for 2 and 6. While the synthetic raw material of 3 was replaced by CuSO₄, the crystal of [Cu(phen)(H₂O)₂(SO₄)]_n was obtained and it has been reported^[28-29]. Thus, the experiment verifies that metal ions and anions affect the formation and structure of complexes.

  In complexes 1-6, each metal ion links two L^2- ligands, and each L^2- ligand links two metal ions to form 1D chains. However, the coordination modes of L^2- are different (Fig. 6). In the previous report, the coordination mode Ⅰ has been showed in DZ-2^[24]. In 1-6, three new coordination modes have been demonstrated. Among them, L^2- shows syn-conformation in coordination mode Ⅱ, while L^2- shows anti-conformation in coordination modes Ⅲ and Ⅳ. In 1 and 2, there is only coordination mode Ⅱ. In 3 and 6, there is only coordination mode Ⅲ. In 5, there is only coordination mode Ⅳ. However, there are coordination modes Ⅲ and Ⅳ in 4. From here it can be seen that the versatile conformation and coordination mode of flexible ligand lead to the structural diversity.

  Figure 6

  

  Figure 6.  Coordination modes in complexes 1-6

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  2.3   TGA and PXRD characterization

  For complexes 1-6, the thermal stability was examined by TGA in the N₂ atmosphere from 30 to 800 ℃ (Fig. 7). For 1, there was no weight loss before 160 ℃. Then there was a weight loss of 3.2% between 160 and 200 ℃, which is in accordance with the loss of the coordinated water molecules (Calcd. 2.7%). Above 270 ℃, 1 began to decompose. The TG curve of 2 was similar to 1. Between 150 and 165 ℃, there was the first weight loss of 3.2%, which is in accordance with the loss of the coordinated water molecules (Calcd. 2.7%). For 3, there was no weight loss below 230 ℃ and then there was a weight loss of 2.5% between 230 and 250 ℃, which is following the loss of the coordinated water molecules (Calcd. 2.7%). Above 250 ℃, 3 began to decompose. For 4, the weight loss of 1.5% below 150 ℃ is in accordance with the loss of the coordinated water molecules (Calcd. 1.4%). Between 150 and 300 ℃, there was no weight loss. Above 300 ℃, 4 began to decompose. For 5, no obvious weight loss was observed below 320 ℃. Above 320 ℃, 5 began to decompose. For 6, the TG curve was similar to 5, and above 270 ℃ 6 began to decompose.

  Figure 7

  

  Figure 7.  TG curves of complexes 1-6

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  To examine the phase purity of the bulk samples, PXRD patterns of complexes 1-6 were investigated at room temperature (Fig.S7). The measured PXRD patterns of synthesized samples are in good agreement with the simulated patterns, which indicate that the samples of 1-6 are pure phase.

  2.4   Photoluminescence property

  Due to the presence of π-electron-rich aromatic backbone and the essential inertness in redox of d¹⁰ transition metal ions, the photoluminescence property of CPs constructed from Zn(Ⅱ) and Cd(Ⅱ) has attracted much attention^[30-32]. The solid-state photoluminescence properties of H₂L ligand, phen ligand, and complexes 4-6 were investigated at room temperature. Excitation and emission spectra of H₂L ligand, phen ligand, and 4-6 were measured.

  In the excitation spectrum, the strongest excitation peaks were 367 nm for H₂L, 377 nm for phen, 367 nm for 4, 354 nm for 5, and 362 nm for 6 (Fig.S8). At the same time, the emission spectra of H₂L, phen, and 4-6 showed the main peaks at 418 nm for H₂L (λ_ex=367 nm), 435 nm for phen (λ_ex=377 nm), 418 nm for 4 (λ_ex=367 nm), 402 nm for 5 (λ_ex=354 nm), and 416 nm for 6 (λ_ex=362 nm), respectively (Fig. 8). Besides, there were shoulder peaks between 460 and 465 nm. Thus, the emission of 4-6 may be assigned to an intraligand π→π* electronic transition. Compared to the free ligand H₂L and phen, the emission maxima of 4-6 were a small amount of blue-shift, which could be attributed to the coordination between L^2- and metal ions.

  Figure 8

  

  Figure 8.  Emission spectra of ligand H₂L, ligand phen, and complexes 4-6 in the solid state at room temperature

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  3.   Conclusions

  In summary, six CPs [Mn(L)(phen)(H₂O)]_n (1), [Co(L)(phen)(H₂O)]_n (2), [Cu(L)(phen)(H₂O)]_n (3), [Zn₂(L)₂ (phen)₂(H₂O)]_n (4), [Zn(L)(phen)]_n (5), and [Cd(L)(phen)₂]_n (6) have been synthesized under solvothermal conditions. Crystallographic analysis indicates that the structures of 1 and 2 are 1D chains based on macrocycle and the L^2- ligands display syn-conformation. In 3-6, the structures are 1D zig-zag chains, and the L^2- ligands display anti-conformation. Solid-state photoluminescent measurements reveal that the main emission of 4-6 lies between phen and H₂L free ligands.

  
  Supporting information is available at http://www.wjhxxb.cn
  
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  Figure 1  (a) Coordination environment of Mn(Ⅱ) in complex 1 with 50% thermal ellipsoid probability (hydrogen atoms have been omitted for clarity); (b) 1D chain in 1; (c) Hydrogen bonding interactions between two 1D chains in 1 indicated by blue dashed lines; (d) 3D framework structure of 1 based on chains with short contact indicated by dashed lines (blue: O5—H5A…O3; black: C28—H28…N1)

  Symmetry codes: ^ⅰ 1-x, 1-y, 1-z; ^ⅱ-1+x, -1+y, z.

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  Figure 2  (a) Coordination environment of Cu(Ⅱ) in complex 3 with 50% thermal ellipsoid probability (hydrogen atoms have been omitted for clarity; (b) 1D chain in 3; (c) Hydrogen bonding interactions between two chains in 3 indicated by black dashed lines; (d) 3D framework of 3 based on chains with short contact indicated by dashed lines (black: O5—H5A…O3; pink: C1—H1…O3; yellow: C8—H8…O3; bright green: C10—H10…O2; blue: C1—H1…O4; orange: C17—H17…N4)

  Symmetry code: ^ⅰ 1+x, -1+y, z.

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  Figure 3  (a) Coordination environment of Zn(Ⅱ) in complex 4 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chains in 4 with hydrogen bonding interactions indicated by dashed lines (red: based on Zn1; green: based on Zn2; black: O9—H9C…O4; yellow: O9—H9D…O2); (c) 3D framework of 4 based on chains with short contact indicated by dashed lines (black: O9—H9C…O4; yellow: O9—H9D…O2; pink: C61—H61…O8; bright green: C25—H25…O5; blue: C50—H50…O8; purple: C9—H9A…S2)

  Symmetry code: ^ⅰ x, -1+y, z.

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  Figure 4  (a) Coordination environment of Zn(Ⅱ) in complex 5 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chain in 5 (red: L^2- ligands and green: phen ligands); (c) Hydrogen bonding interactions between adjacent 1D chains in 5 indicated by black dashed lines (blue: C10—H10…O1; black: C29—H29…O4; turquoise: C16—H16…O2; yellow: C3—H3…O3)

  Symmetry code: ^ⅰ x, y, 1+z.

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  Figure 5  (a) Coordination environment of Cd(Ⅱ) in complex 6 with ellipsoids drawn at 50% probability level (hydrogen atoms are omitted for clarity); (b) 1D chain in 6 (red: L^2- ligands and green: phen ligands); (c) 3D structure of 6 with hydrogen bonds indicated by dashed lines (different colors for different chains)

  Symmetry code: ^ⅰ-0.5+x, 0.5-y, z.

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  Figure 6  Coordination modes in complexes 1-6

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  Figure 7  TG curves of complexes 1-6

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  Figure 8  Emission spectra of ligand H₂L, ligand phen, and complexes 4-6 in the solid state at room temperature

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  Table 1.  Crystal data and structure refinements for complexes 1-6

  Parameter	1	2	3	4	5	6
  Formula	C32H24N4O5S2Mn	C32H24N4O5S2Co	C32H24N4O5S2Cu	C64H46N8O9S4Zn2	C32H22N4O4S2Zn	C44H30N6O4S2Cd
  Formula weight	663.61	667.60	672.21	1 330.07	656.02	883.26
  Crystal system	Triclinic	Triclinic	Triclinic	Triclinic	Triclinic	Orthorhombic
  Space group	P1	P1	P1	P1	P1	Pna21
  a / nm	0.836 19(7)	0.854 6(3)	0.883 47(8)	1.128 42(5)	0.973 89(4)	2.917 77(11)
  b / nm	1.138 23(11)	1.128 8(3)	1.086 31(11)	1.247 33(5)	1.171 90(4)	1.174 31(6)
  c / nm	1.577 27(14)	1.554 9(4)	1.597 12(17)	2.095 95(10)	1.268 70(4)	1.077 93(4)
  α / (°)	92.305(3)	90.994(8)	87.998(4)	93.857 0(10)	80.172 0(10)
  β / (°)	95.826(2)	96.682(10)	79.674(4)	103.215(2)	89.364 0(10)
  γ / (°)	108.812(2)	108.900(9)	69.086(4)	90.488(2)	87.259 0(10)
  V / nm3	1.409 4(2)	1.407 0(6)	1.407 9(2)	2.864 6(2)	1.425 08(9)	3.693 4(3)
  Z	2	2	2	2	2	4
  Dc / (g·cm-3)	1.564	1.576	1.586	1.542	1.529	1.588
  μ / mm-1	0.668	0.810	0.976	1.052	1.055	0.760
  F(000)	682	686	690	1 364	672	1 792
  Unique reflection	6 401	6 410	6 417	10 217	6 518	7 029
  Observed reflection [I > 2σ(I)]	4 451	4 993	3 475	13 071	4 607	8 082
  Number of parameters	400	419	400	785	388	514
  GOF	1.043	1.043	1.052	0.948	1.016	1.072
  Final R indices [I > 2σ(I)]*	R1=0.061 3, wR2=0.114 5	R1=0.048 1, wR2=0.092 9	R1=0.087 5, wR2=0.187 8	R1=0.046 3, wR2=0.135 7	R1=0.049 5, wR2=0.095 5	R1=0.039 3, wR2=0.069 1
  R indices (all data)	R1=0.099 7, wR2=0.135 2	R1=0.070 8, wR2=0.105 2	R1=0.175 8, wR2=0.238 2	R1=0.063 6, wR2=0.152 8	R1=0.084 1, wR2=0.110 4	R1=0.056 4, wR2=0.076 9
  *R1=∑||Fo|-|Fc||/∑|Fo|, wR2=[∑w(Fo2-Fc2)2/∑w(Fo2)2]1/2.

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