English

• 1. INTRODUCTION

  Coordination polymers (CPs), also known as metal-organic frameworks (MOFs), have received considerable attention in the past 30 years due to their many potential applications in the fields of catalysis, chemical sensing, gas storage and separation, and derived functional materials^[1-4]. Through precise regulation of ligands and proper selection of metal ions, CPs with different structures can be synthesized under suitable conditions through coordination bonds. Furthermore, many weak interactions such as π-π stacking interaction and hydrogen bonds have been proven to play a very important role in the self-assembly of CPs^[5]. However, up to now precise design and synthesis of CPs with specific structures and desirable properties remain a great challenge^[6-8].

  So far, many studies have been carried out to construct CPs with isophthalic acid and its derivatives as ligands^[9-12]. The ligands are characterized by their 120° angle between the two carboxylate functional groups and ideal for building either zero-dimensional (0D) metal-organic polyhedra or infinite poly-dimensional CPs. For example, a truncated cuboctahedron constructed from 12 {Cu₂(CO₂)₄} paddle-wheel units was prepared by the reaction of Cu²⁺ and isophthalic ligand^[9]. The work of our group also revealed that pentacarboxylic ligands based on isophthalic acid unit can be used to construct a series of 3D CPs, some of which can be used as highly selective and sensitive luminescent probes to detect nitroaromatics^[10-12]. However, to the best of our knowledge, the assembly behavior of isophthalic ligands containing imidazole functional groups has not been reported.

  In this paper, a new ligand, 5-(6-(1H-imidazol-1-yl)-1, 3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl) isophthalic acid (H₂^ImNIPA), was synthesized by introducing both imidazole and isophthalic units into the 1, 8-naphthalimide skeleton (Scheme 1). It should be noted that the existence of naphthalene ring can not only increase the possibility of π-π weak interaction due to its large conjugate plane, but also affect the luminescence property of the ligand itself or the subsequent CPs^[13]. Two new 2D CPs with both (6, 3) honeycomb-type topology net based on the ligand, [Zn(^ImNIPA)(DMSO)]_n (1) and [Cd(^ImNIPA)(DMSO)]_n (2) (DMSO = dimethyl-sulfoxide), were prepared. Details of structures and properties are presented.

  Scheme 1

  

  Scheme 1.  Synthetic procedure of H₂^ImNIPA

  DownLoad: Full-Size Img PowerPoint

  2. EXPERIMENTAL

  2.1 Materials and methods

  Solvents and reagents were commercially available and used without further purified. The IR spectra were recorded (400~4000 cm^-1) from a Nicolet-20DXB spectrometer using KBr pellets. Thermogravimetric analyses (TGAs) were carried out on a TA-Q50 thermogravimetric analyzer under N₂ atmosphere at the heating rate of 10 ℃/min. Elemental analyses (C, H, and N) were performed on a Vario EL III elemental analyzer. Powder X-ray diffraction patterns (PXRD) data were collected on a D/MAX-2400 X-ray Diffractometer with Cu-Kα radiation (λ = 1.54060 Å) at the scan rate of 5 °/min. NMR spectra were recorded at ambient temperature on a Bruker Avance II 500M spectrometer. The luminescence spectra were collected on a Hitachi F-7000 FL spectrophotometer.

  2.2 Synthesis of ^ImNA

  ^ImNA (6-(1H-imidazol-1-yl)-1H, 3H-benzo[de]-isochromene-1, 3-dione) was obtained according to previous work with some modifications^[14]. A mixture of 4-chloro-1, 8-naphthalic anhydride (11.6 g, 5 mmol), imidazole (5 g, 7.4 mmol), KCl (1 g, 1.4 mmol) and Na₂CO₃ (2 g, 1.9 mmol) in 45 mL DMF was heated at 150 ^oC for 2.5 h, then the mixture was cooled to room temperature. 90 mL ethanol was added into the above mixture and the solid was filtrated. The solid was ultrasonically washed with 10 mL H₂O for 2 times. Finally the crystalline product ^ImNA was obtained by recrystallization from ethanol. Yield: 54%. Anal. Calcd. (%) for C₁₅H₈N₂O₃: C, 64.64; H, 3.07; N, 9.83. Found (%): C, 64.71; H, 3.02; N, 9.89. NMR (500 MHz, DMSO-d₆): δH 8.63 (t, J = 7.5 Hz, 2H), 8.21 (d, J = 10.0 Hz, 1H), 8.03~7.95 (m, 2H), 7.77 (d, J = 2.2 Hz, 2H), 7.30 (s, 1H).

  2.2 Synthesis of H₂^ImNIPA

  A mixture of ^ImNA (2.64 g, 1 mmol), 5-aminoisophthalic acid (1.81 g, 1 mmol) in 35 mL acetic acid was heated at 130 ^oC for 4 h, then the mixture was cooled to room temperature and filtrated. The obtained solid was ultrasonically washed with 30 mL ethanol for 2 times to obtain the target ligand H₂^ImNIPA. Yield: 54%. Anal. Calcd. (%) for C₂₃H₁₃N₃O₆: C, 64.64; H, 3.07; N, 9.83. Found (%): C, 64.71; H, 3.02; N, 9.89. ¹H NMR (500 MHz, DMSO-d₆) δ 13.47 (s, 2H), 8.61 (t, J = 8.0 Hz, 2H), 8.57 (s, 1H), 8.28 (s, 2H), 8.21 (s, 1H), 8.17 (d, J = 8.5 Hz, 1H), 7.99 (dd, J = 14.4, 7.5 Hz, 2H), 7.79 (s, 1H), 7.31 (s, 1H).

  2.3 Synthesis of [Zn(^ImNIPA)(DMSO)]_n (1)

  A mixture of Zn(NO₃)₂∙6H₂O (18 mg, 0.06 mmol), H₂^ImNIPA (8.5 mg, 0.02 mmol), DMSO (3 mL), H₂O (0.6 mL) and ethanol (0.75 mL) was sealed in a scintillation vial and heated to 85 ^oC for 24 h, and then cooled to room temperature. Colorless rhombus-shaped crystals of 1 were obtained (yield 51%, based on H₂^ImNIPA). Anal. Calcd. (%) for C₂₅H₁₇N₃O₇SZn: C, 52.78; H, 3.01; N, 7.39%. Found (%): C, 52.83; H, 3.09; N, 7.32%. IR (KBr pellet, cm^-1): v (C–H) 3121 (m); v (C=O) 1710 (s); v (C=N) 1671 (s); v (C=C) 1610 (m), 1556 (s), 1506 (m), 1491 (w); v_as/v_s(COO^-) 1591 (w), 1445 (m); v (C–N) 1369 (s); δ(C–H) 778 (s).

  2.4 Synthesis of [Cd(^ImNIPA)(DMSO)]_n (2)

  A mixture of Cd(NO₃)₂∙4H₂O (18.5 mg, 0.06 mmol), H₂^ImNIPA (8.5 mg, 0.02 mmol), DMSO (3.5 mL), H₂O (0.6 mL) and N, N-dimethylformamide (DMF, 1.5 mL) was sealed in a scintillation vial and heated to 85 ^oC for 20 h, and then cooled to room temperature. Colorless rhombus-shaped crystals were obtained (yield 58%, based on H₂^ImNIPA). Anal. Calcd. (%) for C₂₅H₁₇CdN₃O₇S: C, 48.75; H, 2.78; N, 6.82%. Found (%): C, 48.69; H, 2.83; N, 6.77%. IR (KBr pellet, cm^-1): v(C–H) 3122 (m); v(C=O) 1711(s); v(C=N) 1670 (s); v(C=C) 1611 (m), 1557 (s), 1506 (m), 1491 (w); v_as/v_s(COO^-) 1591 (w), 1446 (m); v(C–N) 1370 (s); δ(C–H) 778 (s).

  2.5 Structure determination

  Single crystals of 1 and 2 were mounted on glass fibers and intensity data were measured at 296(2) K on a Bruker SMART APEX II CCD area detector system. Data were corrected for absorption effects using the multi-scan technique (SADABS). Structure was solved and refined using the SHELXL-2014/7 software package^[15]. All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were included in the structural model as fixed atoms (using idealized sp²-hybridized geometry and C–H bond lengths of 0.95 Å) "riding" on their respective carbon atoms. Details of X-ray experiment and crystal data are summarized in Table 1. Selected bond lengths and bond angles are listed in Table 2 and 3.

  Table 1

  

  Table 1.  Crystal Data Collection and Structure Refinement Parameters for the Compounds

  DownLoad: CSV

  	1	2
  Empirical formula	C25H17N3O7SZn	C25H17CdN3O7S
  Formula weight	568.84	615.88
  Crystal system	Monoclinic	Monoclinic
  Space group	P21/n	P21/n
  Unit cell dimensions
  a (Å)	9.6312(9)	9.6510(3)
  b (Å)	18.8280(14)	17.0673(4)
  c (Å)	12.9317(12)	14.0936(4)
  α (°)	90	90
  β (°)	91.175(5)	93.411(2)
  γ (°)	90	90
  V (Å3)/Z	2344.5(4) /4	2317.34(11) /4
  μ (mm-1)	1.190	1.087
  Dc (g/cm3)	1.612	1.765
  θ range for data collection (°)	1.911~24.999	1.876~24.998
  F(000)	1160	1232
  Measured reflections	8693	8937
  Independent reflections	4101	4050
  Observed reflections (I > 2σ(I))	2127	3012
  Rint	0.0690	0.0455
  Parameters refined	344	334
  Goodness of fit on F2	1.001	1.071
  Ra/Rwb	0.0692/0.1394	0.0489/0.0712
  Max/mean shift in the final cycle	0.000/0.000	0.000/0.000
  aR = ∑(||Fo| – |Fc||)/∑|Fo|, bRw = {∑w[(Fo2 – Fc2)2]/∑w[(Fo2)2]}1/2, w = 1/[σ2(Fo2) + (aP)2 + bP], P = (Fo2 + 2Fc2)/3 1, a = 0.0983, b = 0.0000; 2, a = 0.0658, b = 0.8994

  Table 2

  

  Table 2.  Selected Bond Lengths (Å) and Bond Angles (°) for 1

  DownLoad: CSV

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Zn(1)–N(3)	2.005(6)		Zn(1)–O(2A)	1.913(5)		Zn(1)–O(4B)	1.953(5)
  Zn(1)–O(7)	2.015(5)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(2A)–Zn(1)–O(4B)	115.4(2)		O(4B)–Zn(1)–N(3)	103.1(2)		O(4B)–Zn(1)–O(7)	116.0(2)
  O(2A)–Zn(1)–N(3)	126.9(3)		O(2A)–Zn(1)–O(7)	102.0(2)		N(3)–Zn(1)–O(7)	91.8(3)
  Symmetry transformation: A: x+1, y, z+1; B: x+3/2, –y+1/2, z+1/2

  Table 3

  

  Table 3.  Selected Bond Lengths (Å) and Bond Angles (°) for 2

  DownLoad: CSV

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Cd(1)–N(3)	2.214(5)		Cd(1)–O(7)	2.279(4)		Cd(1)–O(2A)	2.373(4)
  Cd(1)–O(4B)	2.217(4)		Cd(1)–O(1A)	2.344(4)		Cd(1)–O(3B)	2.612(4)
  Angle	(°)		Angle	(°)		Angle	(°)
  N(3)–Cd(1)–O(4B)	134.78(17)		O(7)–Cd(1)–O(1A)	84.97(15)		N(3)–Cd(1)–O(3B)	84.03(16)
  N(3)–Cd(1)–O(7)	83.44(17)		N(3)–Cd(1)–O(2A)	100.80(16)		O(4B)–Cd(1)–O(3B)	53.33(13)
  O(4B)–Cd(1)–O(7)	103.11(15)		O(4B)–Cd(1)–O(2A)	109.50(15)		O(7)–Cd(1)–O(3B)	119.05(14)
  N(3)–Cd(1)–O(1A)	137.39(17)		O(7)–Cd(1)–O(2A)	126.62(14)		O(1A)–Cd(1)–O(3B)	136.52(14)
  O(4B)–Cd(1)–O(1A)	87.80(15)		O(1A)–Cd(1)–O(2A)	56.13(13)		O(2A)–Cd(1)–O(3B)	114.30(13)
  Symmetry transformation: A: x–1, y, z–1; B: x–1.5, –y+0.5, z–0.5

  3. RESULTS AND DISCUSSION

  3.1 Crystal structure of 1

  Compound 1 crystallizes in the monoclinic P2₁/n space group with the asymmetric unit comprised of one crystallographically independent Zn^II ion, one ^ImNIPA^2- ligand and one coordinated DMSO molecule. As shown in Fig. 1a, each Zn^II ion is four-coordinated and displays a distorted tetrahedral geometry consisting of one N atom from the imidazole group and three O atoms, two of which are from two ^ImNIPA^2- ligands and the other one from a DMSO molecule. The Zn–O bond lengths range from 1.924(8) to 2.001(8) Å and the Zn–N bond length is 2.013(9) Å, which are all close to the values found in other reported Zn^II complexes^{[16, 17]}.

  Figure 1

  

  Figure 1.  Structure of 1. (a) Coordination environment of the Zn^II atom. Symmetry codes: A: x+1, y, z+1; B: x+3/2, –y+1/2, z+1/2. (b) 2D layer structure viewed along the b direction. (c) Topology of the 2D net. (d) Packing diagram viewed along the a direction. DMSO molecules are omitted for clarity. π-π interaction is represented as green dotted line

  DownLoad: Full-Size Img PowerPoint

  Each ligand is coordinated to three Zn ions and bears a μ₃-κ_O¹: κ_O¹: κ_N¹ coordination mode (Scheme 2). The ligand is severely distorted. 69.82° and 72.39° dihedral angles are observed between the naphthalene and benzene rings and the naphthalene and imidazole rings of the ligand, respectively.

  Scheme 2

  

  Scheme 2.  Two coordination modes of the ligands in the two compounds

  DownLoad: Full-Size Img PowerPoint

  Both the inorganic and organic nodes can be treated as 3-connected nodes, and the combination of them leads to a neutral 2D layer featuring a 3-connected net with (6, 3) honeycomb-type topology (Fig. 1b and 1c). The layers are packed along the b direction and the coordinated DMSO molecules are hung on the layer surface. Inside the layer, the nearest Zn···Zn separation is 9.84 Å (bridged by the carboxylate group). Due to the torsion of the ligand, the 2D net shows a wave-like structure motif. The neighboring layers are packed in such a close mode that offset face-to-face π-π interactions are formed between neighboring naphthalene rings from two layers with the ring-ring separation of 3.66 Å (Fig. 1d). Such strong π-π interactions connect the 2D coordination layers into a 3D supramolecular network.

  3.2 Crystal structure of 2

  2 also bears a 2D structure but based on 6-coordinated Cd²⁺ ions connected by the ^ImNIPA^2- ligands. As shown in Fig. 2a, each Cd^II ion displays a distorted {NO₅} triangular prism geometry with one N atom from the imidazole group of one ^ImNIPA^2- ligand, four O atoms from two ^ImNIPA^2- ligands, and one O atom from a DMSO molecule. The Cd–O lengths and O–Cd–O angles range from 2.217(4) to 2.612(4) Å and 53.33(13) to 136.52(14)°, respectively. In contrast, the Cd–N bond length is 2.214(5) Å and the N–Cd–O angles fall in the range of 83.44(17)~134.78(17)°. As shown in Scheme 2, each Cd^II atom is connected to three different ^ImNIPA^2- ligands and exhibits a μ₃-κ_O²: κ_O²: κ_N¹ coordination mode.

  Figure 2

  

  Figure 2.  Structure of 2. (a) Coordination environment of the Cd^II ions. Symmetry codes: A: x–1, y, z–1; B: x–1.5, –y+0.5, z–0.5; (b) 2D layer structure viewed along the b direction. (c) Packing diagram viewed along the a direction. DMSO molecules are omitted for clarity. π-π interaction is represented as green dotted line

  DownLoad: Full-Size Img PowerPoint

  Similar to that in 1, both inorganic and organic nodes feature 3-connection motif and the resulted network bears a 2D (6, 3) honeycomb-type topology. The layers are extended along the ac plane (Fig. 2b). π-π interaction also plays an important role in stabilizing the structure of 2. Offset face-to-face π-π interaction between the naphthalene rings from two neighboring layers is observed. The corresponding ring-ring separation is 4.04 Å (Fig. 2c).

  3.3 Characterization of the compounds

  The phase purity of 1 and 2 was confirmed by powder X-ray diffraction (PXRD) at room temperature (Fig. 3). The peak positions of 1 and 2 are highly consistent with their corresponding simulated patterns, fully demonstrating the purity of their crystalline phases.

  Figure 3

  

  Figure 3.  PXRD patterns of 1 and 2

  DownLoad: Full-Size Img PowerPoint

  The thermogravimetric analysis (TGA) was carried out to investigate the thermal stability of the two compounds (Fig. 4). The results reveal that 1 and 2 are stable below 314 ^oC. Above this temperature, the material shows a striking weight loss, indicating complete decomposition of the compounds.

  Figure 4

  

  Figure 4.  TGA curves of 1 and 2

  DownLoad: Full-Size Img PowerPoint

  The luminescence properties of 1, 2 and ligand H₂^ImNIPA were investigated in the solid state at room temperature (Fig. 5). 1 exhibits a maximum emission peak at 432 nm upon excitation at 365 nm, and in the same condition the maximum emission peak at 435 nm is observed for 2. In contrast, H₂^ImNIPA bears maximum peak around 452 nm, which is redshift about 20 nm in comparison to those of 1 and 2. This shift of the emission peak may be ascribed to the combination effects of the coordination interactions of ^ImNIPA^2- to metal ions and the deprotonation of H₂^ImNIPA ligand^[12].

  Figure 5

  

  Figure 5.  Luminescence emission spectra of 1, 2 and H₂^ImNIPA under the excitation of 365 nm

  DownLoad: Full-Size Img PowerPoint

  4. CONCLUSION

  In summary, two novel coordination polymers based on a new ligand containing both imidazole and isophthalic units were synthesized under solvothermal conditions and characterized detailedly. Both compounds have 2D layer structures that feature (6, 3) honeycomb-type topology. In addition, the 2D layers are further extended into 3D supramolecular frameworks via π-π stacking interactions between the naphthalene rings from the adjacent 2D layers. The thermal-stability and luminescence properties of the compounds were studied. This work provides a good example for the design and synthesis of new CPs based on imidazolato/isophthalato functionalized ligand.

  
  
• 1. [1]

     Sagara, Y.; Yamane, S.; Mitani, M.; Weder, C.; Kato, T. Mechanoresponsive luminescent molecular assemblies: an emerging class of materials. Adv. Mater. 2016, 28, 1073–1095. doi: 10.1002/adma.201502589

  2. [2]

     Zhao, H.; Ni, J.; Zhang, J. J.; Liu, S. Q.; Sun, Y. J.; Zhou, H.; Li, Y. Q.; Duan, C. Y. A trichromatic MOF composite for multidimensional ratiometric luminescent sensing. Chem. Sci. 2018, 9, 2918–2926. doi: 10.1039/C8SC00021B

  3. [3]

     Zhang, J. J.; Wojtas, L.; Larsen, R. W.; Eddaoudi, M.; Zaworotko, M. J. Temperature and concentration control over interpenetration in a polymorphic metal-organic material. J. Am. Chem. Soc. 2009, 131, 17040–17041. doi: 10.1021/ja906911q

  4. [4]

     Xia, Z. Q.; He, C.; Wang, X. G.; Duan, C. Y. Modifying electron transfer between photoredox and organocatalytic units via framework interpenetration for β-carbonyl functionalization. Nat. Commun. 2017, 8, 361. doi: 10.1038/s41467-017-00416-8

  5. [5]

     Liu, S. Q.; Li, X. J.; Di, L.; Ding, B. J.; Zhang, J. J. Interesting weak interactions in three silver coordination polymers based on tetrafluoro benzenedicarboxylate and benzonitrile ligands. Chin. J. Struct. Chem. 2013, 32, 969–974.

  6. [6]

     Li, Z. Y.; Zhang, J. J.; Liu, S. Q.; Zhang, H.; Sun, Y. J.; Liu, X. Y.; Zhai, B. Heterometallic hexanuclear [Ln₄Cr₂] cluster-based three-dimensional sulfate frameworks as a magnetic refrigerant and single molecular magnet. Cryst. Growth Des. 2018, 18, 7335–7342. doi: 10.1021/acs.cgd.8b00966

  7. [7]

     Wang, X. Y.; Li, G. T.; Sun, D. Y.; Zhang, Y.; Liu, D. X.; Xu, Z. L. A new luminescent Cd(II) coordination polymer constructed with 2-(carboxymethoxy)benzoic acid. Chin. J. Struct. Chem. 2018, 37, 1939–1944.

  8. [8]

     Feng, X.; Guo, N.; Chen, H. P.; Wang, H. L.; Yue, L. Y.; Chen, X.; Ng, S. W.; Liu, X. F.; Ma, L. F.; Wang, L. Y. A series of anionic host coordination polymers based on azoxybenzene carboxylate: structures, luminescence and magnetic properties. Dalton Trans. 2017, 46, 14192–14200. doi: 10.1039/C7DT02974H

  9. [9]

     Eddaoudi, M.; Kim, J.; Wachter, J. B.; Chae, H. K.; O'Keeffe, M.; Yaghi, O. M. Porous metal organic polyhedra: 25 Å cuboctahedron constructed from 12 Cu₂(CO₂)₄ paddle-wheel building blocks. J. Am. Chem. Soc. 2001, 123, 4368–4369. doi: 10.1021/ja0104352

  10. [10]

      Dai, Y.; Zhang, J. J.; Liu, S. Q.; Zhou, H.; Sun, Y. J.; Pan, Y. Z.; Ni, J.; Yang, J. S. A trichromatic and white-light-emitting MOF composite for multi-dimensional and multi-response ratiometric luminescent sensing. Chem. -Eur. J. 2018, 24, 9555–9564. doi: 10.1002/chem.201801686

  11. [11]

      Dai, Y.; Zhou, H.; Song, X. D.; Zhang, J. J.; Hao, C.; Di, L.; Wang, Y. X.; Ni, J.; Wang, H. L. Two (5, 5)-connected isomeric frameworks as highly selective and sensitive photoluminescent probes of nitroaromatics. CrystEngComm. 2017, 19, 2786–2794. doi: 10.1039/C7CE00236J

  12. [12]

      Di, L.; Zhang, J. J.; Liu, S. Q.; Ni, J.; Zhou, H.; Sun, Y. J. Two dynamic, ABW-type metal organic frameworks built of pentacarboxylate and Zn²⁺ as photoluminescent probes of nitroaromatics. Cryst. Growth Des. 2016, 16, 4539–4546. doi: 10.1021/acs.cgd.6b00656

  13. [13]

      Reger, D. L.; Leitner, A. P.; Smith, M. D. Supramolecular metal-organic frameworks of s- and f‑block metals: impact of 1, 8-naphthalimide functional group. Cryst. Growth Des. 2016, 16, 527–536. doi: 10.1021/acs.cgd.5b01575

  14. [14]

      Peters, A. T.; Bide, M. J. Amino derivatives of 1, 8-naphthalic anhydride and derived dyes for synthetic-polymer fibers. Dyes Pigm. 1985, 6, 349–375. doi: 10.1016/0143-7208(85)85005-1

  15. [15]

      Sheldrick, G. M. SHELXL-2014/7: Program for the Solution of Crystal Structures. University of Göttingen, Göttingen 2014.

  16. [16]

      Yang, J. S.; Zhu, J.; Liu, R. B.; Hu, T.; Chang, Z. D.; Meng, C. G.; Zhang, J. J. Syntheses and characterization of four 2D metal-organic networks based on rigid imidazolate/carboxylate functionalized ligand-effect of the torsion of the ligands on crystal structures and properties. Inorg. Chim. Acta 2013, 394, 117–126. doi: 10.1016/j.ica.2012.07.031

  17. [17]

      Shi, Y.; Liu, X.; Shan, Y. Y.; Zhang, X.; Kong, W. B.; Lu, Y. N.; Tan, Z. D.; Li, X. L. Naked-eye repeatable off-on-off and on-off-on switching luminescence of copper(I)-1H-imidazo[4, 5-f][1, 10]phenanthroline complexes with reversible acid-base responses. Dalton Trans. 2019, 48, 2430–2441. doi: 10.1039/C8DT04538K

• 

  Scheme 1  Synthetic procedure of H₂^ImNIPA

  下载: 全尺寸图片 幻灯片
  

  Figure 1  Structure of 1. (a) Coordination environment of the Zn^II atom. Symmetry codes: A: x+1, y, z+1; B: x+3/2, –y+1/2, z+1/2. (b) 2D layer structure viewed along the b direction. (c) Topology of the 2D net. (d) Packing diagram viewed along the a direction. DMSO molecules are omitted for clarity. π-π interaction is represented as green dotted line

  下载: 全尺寸图片 幻灯片
  

  Scheme 2  Two coordination modes of the ligands in the two compounds

  下载: 全尺寸图片 幻灯片
  

  Figure 2  Structure of 2. (a) Coordination environment of the Cd^II ions. Symmetry codes: A: x–1, y, z–1; B: x–1.5, –y+0.5, z–0.5; (b) 2D layer structure viewed along the b direction. (c) Packing diagram viewed along the a direction. DMSO molecules are omitted for clarity. π-π interaction is represented as green dotted line

  下载: 全尺寸图片 幻灯片
  

  Figure 3  PXRD patterns of 1 and 2

  下载: 全尺寸图片 幻灯片
  

  Figure 4  TGA curves of 1 and 2

  下载: 全尺寸图片 幻灯片
  

  Figure 5  Luminescence emission spectra of 1, 2 and H₂^ImNIPA under the excitation of 365 nm

  下载: 全尺寸图片 幻灯片

  Table 1.  Crystal Data Collection and Structure Refinement Parameters for the Compounds

  	1	2
  Empirical formula	C25H17N3O7SZn	C25H17CdN3O7S
  Formula weight	568.84	615.88
  Crystal system	Monoclinic	Monoclinic
  Space group	P21/n	P21/n
  Unit cell dimensions
  a (Å)	9.6312(9)	9.6510(3)
  b (Å)	18.8280(14)	17.0673(4)
  c (Å)	12.9317(12)	14.0936(4)
  α (°)	90	90
  β (°)	91.175(5)	93.411(2)
  γ (°)	90	90
  V (Å3)/Z	2344.5(4) /4	2317.34(11) /4
  μ (mm-1)	1.190	1.087
  Dc (g/cm3)	1.612	1.765
  θ range for data collection (°)	1.911~24.999	1.876~24.998
  F(000)	1160	1232
  Measured reflections	8693	8937
  Independent reflections	4101	4050
  Observed reflections (I > 2σ(I))	2127	3012
  Rint	0.0690	0.0455
  Parameters refined	344	334
  Goodness of fit on F2	1.001	1.071
  Ra/Rwb	0.0692/0.1394	0.0489/0.0712
  Max/mean shift in the final cycle	0.000/0.000	0.000/0.000
  aR = ∑(||Fo| – |Fc||)/∑|Fo|, bRw = {∑w[(Fo2 – Fc2)2]/∑w[(Fo2)2]}1/2, w = 1/[σ2(Fo2) + (aP)2 + bP], P = (Fo2 + 2Fc2)/3 1, a = 0.0983, b = 0.0000; 2, a = 0.0658, b = 0.8994

  下载: 导出CSV

  Table 2.  Selected Bond Lengths (Å) and Bond Angles (°) for 1

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Zn(1)–N(3)	2.005(6)		Zn(1)–O(2A)	1.913(5)		Zn(1)–O(4B)	1.953(5)
  Zn(1)–O(7)	2.015(5)
  Angle	(°)		Angle	(°)		Angle	(°)
  O(2A)–Zn(1)–O(4B)	115.4(2)		O(4B)–Zn(1)–N(3)	103.1(2)		O(4B)–Zn(1)–O(7)	116.0(2)
  O(2A)–Zn(1)–N(3)	126.9(3)		O(2A)–Zn(1)–O(7)	102.0(2)		N(3)–Zn(1)–O(7)	91.8(3)
  Symmetry transformation: A: x+1, y, z+1; B: x+3/2, –y+1/2, z+1/2

  下载: 导出CSV

  Table 3.  Selected Bond Lengths (Å) and Bond Angles (°) for 2

  Bond	Dist.		Bond	Dist.		Bond	Dist.
  Cd(1)–N(3)	2.214(5)		Cd(1)–O(7)	2.279(4)		Cd(1)–O(2A)	2.373(4)
  Cd(1)–O(4B)	2.217(4)		Cd(1)–O(1A)	2.344(4)		Cd(1)–O(3B)	2.612(4)
  Angle	(°)		Angle	(°)		Angle	(°)
  N(3)–Cd(1)–O(4B)	134.78(17)		O(7)–Cd(1)–O(1A)	84.97(15)		N(3)–Cd(1)–O(3B)	84.03(16)
  N(3)–Cd(1)–O(7)	83.44(17)		N(3)–Cd(1)–O(2A)	100.80(16)		O(4B)–Cd(1)–O(3B)	53.33(13)
  O(4B)–Cd(1)–O(7)	103.11(15)		O(4B)–Cd(1)–O(2A)	109.50(15)		O(7)–Cd(1)–O(3B)	119.05(14)
  N(3)–Cd(1)–O(1A)	137.39(17)		O(7)–Cd(1)–O(2A)	126.62(14)		O(1A)–Cd(1)–O(3B)	136.52(14)
  O(4B)–Cd(1)–O(1A)	87.80(15)		O(1A)–Cd(1)–O(2A)	56.13(13)		O(2A)–Cd(1)–O(3B)	114.30(13)
  Symmetry transformation: A: x–1, y, z–1; B: x–1.5, –y+0.5, z–0.5

  下载: 导出CSV
•