English

• 0.   Introduction

  1, 3, 4-Oxadiazole and its derivatives are important compounds, which have gained considerable attentions in recent years. 1, 3, 4-Oxadiazole compounds play a significant role in medicine and pesticides. Some 1, 3, 4-oxadiazole derivatives have important physiolo-gical activities^[1-5], such as analgesic^[6], antibacterial^[7], anticancer^[8], anti-inflammatory^[9] and insecticides^[10]. The 1, 3, 4-oxadiazole ring can be introduced into organic compounds to synthesize special materials, such as electron transporting materials^[11], corrosion inhibitors of metals^[12-14] and stabilizers for polymer^[15].

  1, 3, 4-Oxadiazole rings have π-electron conju-gated planar structures. The nitrogen and oxygen atoms on the oxadiazole rings have strong electron donation capacities, which can coordinate to transition metal ions and form stable complexes^[16-19]. Some metal complexes of 1, 3, 4-oxadiazole derivatives exhibit good biological activities^[20-22]. Khler and Rentschler reported the first 1, 3, 4-oxadiazole based dinuclear iron(Ⅱ) complex showing spin crossover behavior in 2016^[23]. Although some metal complexes with substituted l, 3, 4-oxadiazole have been reported, the metal complexes with 2-methyl-5-(2-pyridyl)-1, 3, 4-oxadiazole have not been reported so far. Here we reported two metal complexes [Cu₂L₂(μ-Cl)₂Cl₂] (1) and [CdL₂(NO₃)₂] (2), where L=2-methyl-5-(2-pyridyl)-1, 3, 4-oxadiazole. The crystal structure, spectral properties and thermal stability are studied.

  1.   Experimental

  1.1   Materials and measurements

  All chemicals were analytical grade and used without further purification. The C, H, N elemental analyses were performed on a Perkin-Elmer240. Melting points were determined on an X4 digital microscopic melting point apparatus and uncorrected. The UV-Vis spectra were recorded on an UV-6000PC UV-Vis absorption spectrophotometer. The IR spectra were recorded from 400 to 4 000 cm^-1 using KBr pellets on an IR prestige-21 Shimadzu infrared spectrophotometer. Fluorescence spectral data were obtained on a F-2700FL spectrophotometer. ¹H NMR spectra were recorded on a Bruker Avance300 spectrometer at ambient temperature in CDCl₃ using TMS as an internal standard. Single crystal data were collected on a Bruker SMART APEX Ⅱ CCD single crystal X-ray diffractometer. Thermogravimetric analysis (TGA) was performed on a NETZSCH STA49F3 thermal analyzer in nitrogen atmosphere at the heating rate of 10 K·min^-1.

  1.2   Synthesis of 2-methyl-5-(2-pyridyl)-1, 3, 4-oxadiazole (L)^[24]

  The 2, 5-disubstituted 1, 3, 4-oxadiazole are prep-ared from diacylhydrazines using p-toluenesulfonyl chloride or benzenesulfonyl chloride as dehydrating reagents. N-acetyl-N′-(2-picolinoyl)hydrazine (5.37 g, 30 mmol), p-toluenesulfonyl chloride (8.6 g, 45 mmol) and triethylamine (12.5 mL, 60 mmol) were added to acetonitrile (150 mL). The mixture was stirred for 5 h at room temperature, and then refluxed for 10 h at 90℃. Then the solvent was evaporated. The residue was dissolved in 10% NaOH solution (100 mL) and extracted with CHCl₃ (3×80 mL). The organic phase was dried over MgSO₄ and concentrated. Recrystalliza-tion from ethyl acetate gave a colorless crystals (4.13 g, Yield: 85.6%), m.p. 96~97 ℃. Anal. Calcd. For C₈H₇N₃O(%): C 59.62, H 4.38, N 26.07; Found(%): C 59.45, H 4.27, N 25.93. ¹H NMR (CDCl3): δ 2.704 (s, 3H), 7.470~8.792 (m, 4H). ¹³C NMR (CDCl₃): δ 164.729, 164.023, 150.127, 143.462, 137.307, 125.754, 122.869, 11.168. IR (KBr, cm^-1): 3 062, 3 000, 2 930, 1 578, 1 553, 1 454, 1 358, 1 254, 1 152, 1 103, 1 047, 1 034, 971, 955, 798, 749, 709. UV-Vis (λ_max/nm): 240, 276.

  1.3   Synthesis of complex 1

  0.170 Grams of CuCl₂·2H₂O (1 mmol) was added to a warm solution of L (0.322 g, 2 mmol) in 30 mL acetonitrile. The solution turned green and a preci-pitation formed. The solution gradually became clear after 4 mL of distilled water was added, filtered, and the filtrate was left to stand at room temperature for slowly evaporating. Several days later green crystals were collected (0.236 g, Yield: 48.0%), and a single crystal suitable for X-ray was picked. Anal. Calcd. For C₁₆H₁₄Cl₄Cu₂N6O₂(%): C 32.50, H 2.39, N 14.22; Found(%): C 32.38, H 2.33, N14.07. IR (KBr, cm^-1): 3 074, 3 019, 2 965, 1 600, 1 575, 1 560, 1 488, 1 411, 1 248, 1 161, 1 097, 1 057, 1 046, 1 027, 940, 922, 788, 757, 740, 707. UV-Vis (λ_max/nm): 240, 275.

  1.4   Synthesis of complex 2

  0.231 g of Cd(NO₃)₂·4H₂O (0.75 mmol) was added to a warm solution of L (0.242 g, 1.5 mmol) in 20 mL acetonitrile. A colorless mixture was formed and filtered. The filtrate was left to stand at room tempera-ture for slowly evaporating. Several days later colorless crystals were obtained (0.199 g, Yield: 42.0%). A single crystal suitable for X-ray was picked. Anal. Calcd. for C₁₆H₁₄CdN₈O₈(%): C 34.39, H 2.53, N 20.05; Found(%): C 34.27, H 2.44, N 19.87. IR (KBr, cm^-1): 3 072, 2 940, 1 583, 1 567, 1 555, 1 492, 1 433, 1 421, 1 398, 1 378, 1 289, 1 160, 1 135, 1 098, 1 047, 1 034, 1 011, 948, 920, 818, 803, 754, 735, 707. UV-Vis (λ/nm): 240, 276.

  1.5   Crystal structure determination

  Well-shaped single crystals of L, 1 and 2 were picked for X-ray diffraction studies. The data were collected at 296(2) K on a Bruker SMART APEX Ⅱ CCD X-ray diffractometer with a detector distance of 5 cm and frame exposure time of 10s using graphite-monochromated Mo Kα (λ=0.071 073 nm) radiation. The structures were solved by direct methods and refined on F² by full-matrix least squares procedures using SHELXTL software^[25]. All non-hydrogen atoms were anisotropically refined, and all hydrogen atoms on carbon atoms were generated geometrically and allowed to ride on the parent atoms, but not refined. Crystal data and structure refinement for L, 1 and 2 are listed in Table 1. Selected bond lengths and angles for L, 1 and 2 are listed in Table 2. The molecular graphics were prepared by using the DIAMOND 3.1 program.

  Table 1

  

  Table 1.  Crystal data and structure refinement for L, 1 and 2

  下载: 导出CSV

  Compound	L	1	2
  Formula	C8H7N3O	C8H7Cl2CuN3O	C8H7Cd0.5O4
  Formula weight	161.17	295.61	279.38
  Crystal system	Monoclinic	Triclinic	Monoclinic
  Space group	P21/c	P1	C2/c
  a/nm	0.786 3(8)	0.826 4(5)	1.090 0(3)
  b/nm	1.069 6(11)	0.851 7(5)	1.384 4(4)
  c/nm	0.938 9(10)	0.901 1(8)	1.362 3(4)
  α/(°)		109.627(8)
  β/(°)	99.344(13)	113.387(8)	99.090(4)
  γ/(°)		99.513(6)
  (V/nm3	0.779 1(14)	0.514 6(6)	2.029 9(11)
  Z	4	2	8
  Dc/(g·cm3)	1.374	1.908	1.828
  θ range/(°)	2.63-26.00	2.71-25.50	2.40-25.79
  μ/mm-1	0.096	2.613	1.141
  F(000)	336	294	1112
  Rint	0.027 9	0.021 9	0.033 3
  Reflection collected	5 584	3 752	7 223
  Independent reflection	1 506	1 881	1 933
  Observed reflection	1 188	1 771	1 682
  Data, restrain, parameter	1 506, 0, 111	1 881, 0, 138	1 933, 2, 151
  Goodness-of-fit on F2	1.050	1.091	1.108
  R1, wR2 [I > 2σ(I)]	0.038 2, 0.100 4	0.023 0, 0.062 5	0.028 0, 0.060 8
  R1, wR2 (all data)	0.049 3, 0.107 1	0.024 5, 0.063 1	0.034 6, 0.062 6
  (Δρ)max, (Δρ)min/(e·nm-3)	183, -107	337, -313	361, -320

  Table 2

  

  Table 2.  Selected bond lengths (nm) and bond angles (°) for L, 1 and 2

  下载: 导出CSV

  L
  C2-N1	0.128 26(19)	C3-O1	0.135 68(18)	N1-N2	0.140 7(2)
  C2-O1	0.136 59(17)	C3-N2	0.128 9(2)
  N1-C2-O1	112.36(14)	C3-O1-C2	102.77(11)	C3-N2-N1	106.30(10)
  N2-C3-O1	112.32(11)	C2-N1-N2	106.25(12)
  1
  Cu1-Cl1	0.272 52(13)	Cu1-Cl2	0.223 29(16)	Cu1-N3	0.210 2(3)
  Cu1-C11ⅰ	0.226 86(10)	Cu1-N2	0.202 5(2)
  N2-Cu1-N3	79.18(10)	N3-Cu1-Cl2	166.14(6)	Cl2-Cu1-Cl1	101.89(4)
  N2-Cu1-Cl2	93.43(9)	N3-Cu1-C11ⅰ	91.19(8)	Cl1-Cu1-Cl1ⅰ	90.89(5)
  N2-Cu1-C11ⅰ	168.72(6)	N3-Cu1-Cl1	90.50(6)
  N2-Cu1-Cl1	95.00(7)	Cl2-Cu1-Cl1ⅰ	94.76(7)
  2
  Cd1-N2	0.248 9(2)	Cd1-02	0.245 4(2)	Cd1-O3	0.247 9(2)
  Cd1-N3	0.238 9(2)
  N3ⅰ-Cd1-N3	113.98(12)	N3-Cd1-N2	68.93(8)	O2ⅰ-Cd1-N2ⅰ	154.16(7)
  N3-Cd1-O2ⅰ	104.18(8)	N2ⅰ-Cd1-N2	130.77(11)	O2ⅰ-Cd1-O2	80.72(10)
  N3-Cd1-O2	125.82(7)	O2-Cd1-N2ⅰ	74.61(7)
  N3-Cd1-N2ⅰ	84.59(8)	O2-Cd1-N2	154.16(8)
  Symmetry codes: ⅰ2-x, 1-y, 1-z for 1; ⅰ2-x, y, 3/2-z for 2.

  CCDC: 1851091, L; 1851090, 1; 1851089, 2.

  2.   Results and discussion

  2.1   Crystal structural analyses

  2.1.1   Crystal structure of L

  X-ray diffraction structure analysis reveals that L crystallizes in monoclinic system with space group P2₁/c. The oxadiazole ring and pyridyl ring of L are close to coplanar. The dihedral angle between them is 10.66°. In the crystals there is a non-classical hydrogen bond interactions of C1-H1A…N2^ⅰ, and a weak face-to-face π…π interaction exists between the 1, 3, 4-oxadiazole ring and pyridyl ring (Table 3 and Fig. 1). All these interactions link the L molecules into a two-dimensional network structure.

  Table 3

  

  Table 3.  Hydrogen bond and π…π interactions for align="left"

  下载: 导出CSV

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C1-H1A …N2ⅰ	0.095 94	0.255 21	0.349 7(4)	168.40
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg1…Cg2ⅱ			3.891(4)	10.66
  Cg1: O1, C2, N1, N2, C3; Cg2: N3, C4, C5, C6, C7, C8; Symmetry codes: ⅰ2-x, -1/2+y, 1/2-z; ⅱ1-x, 2-y, -z.

  Figure 1

  

  Figure 1.  (a) Structure of L with atomic labeling; (b) 2D structure of L linked by hydrogen bond and π…π interactions

  Symmetry codes: ^ⅰ2-x, -1/2+y, 1/2-z; ^ⅱ1-x, 2-y, -z; ^ⅲ2-x, 1/2+y, 1/2-z

  下载: 全尺寸图片 幻灯片

  2.1.2   Crystal structure of 1

  Complex 1 is a double-bridged binuclear Cu(Ⅱ) complex (Fig. 2) crystallizing in triclinic system with space group P1. Two copper(Ⅱ) ions are bridged by two Cl atoms (Cl1 and Cl1^ⅰ). The N2, N3, Cl1^ⅰ and Cl2 atoms are close to coplanar around the Cu1(Ⅱ) ion. The Cl1 atom sits at the side of the plane making the center Cu1(Ⅱ) ion form a distorted tetragonal geometry [CuCl₃N₂]. The bond lengths of Cu1-N2, Cu1-N3, Cu1-Cl1 and Cu1-Cl2 are 0.202 5(2), 0.210 2(3), 0.272 52(13) and 0.223 29(16) nm, respectively. The bond lengths of Cu-N are within the normal ranges observed for distorted tetragonal Cu(Ⅱ) complex or trigonal bipyramid Cu(Ⅱ) complexes^[26].

  Figure 2

  

  Figure 2.  (a) Structure of 1 with atomic labeling; (b) 2D structure of 1 through the hydrogen bond interactions; (c) 3D structure of 1 linked by hydrogen bond and π…π interactions

  Symmetry codes: ^ⅰ2-x, 1-y, 1-z; ^ⅱ2-x, 1-y, -z; ^ⅲ-1+x, -1+y, -1+z

  下载: 全尺寸图片 幻灯片

  In complex 1, there are three non-classical intermolecular hydrogen bonding interactions: C5-H5…Cl1^ⅰ, C7-H7…Cl2^ⅲ and C8-H8…Cl1^ⅱ. All these intermolecular hydrogen bonding interactions link complex 1 molecules into a two-dimensional network structure (Table 4 and Fig. 2). A face-to-face π…π interaction exists between the 1, 3, 4-oxadiazole and pyridyl rings with a centroid-centroid distance of 0.387 4(4) nm (Table 4). Another face-to-face π…π interaction is found between the pyridyl rings with a centroid-centroid distance of 0.362 9(4) nm. Complex 1 molecules are linked into a layered three-dimensional networks through these π…π interactions (Fig. 2).

  Table 4

  

  Table 4.  Hydrogen bond and π…π interactions for 1

  下载: 导出CSV

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C8-H8…C11ⅰ	0.093 05	0.268 37	0.324 2(4)	119.30
  C5-H5…C11ⅱ	0.092 97	0.270 21	0.352 8(4)	148.46
  C7-H7…C12ⅲ	0.092 95	0.273 53	0.365 5(5)	170.21
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg3…Cgⅱ			0.3874(4)	2.41
  Cg4…Cg4ⅳ			0.3629(4)	0.00
  Cg3: O1, C2, N1, N2, C3; Cg4: N3, C4, C5, C6, C7, C8; Symmetry codes: ⅰ2-x, 1-y, 1-z; ⅱ2-x, 1-y, -z; ⅲ-1+x, -1+y, -1+z; ⅳ1-x, 1-y, -z.

  2.1.3   Crystal structure of 2

  Complex 2 crystallizes in monoclinic system with space group C2/c. The center Cd1(Ⅱ) ion are coordinated by two molecules of L and two nitrate ions. Four coordinated nitrogen atoms (N2, N2^ⅰ, N3, N3^ⅰ) and two oxygen atoms (O2, O2^ⅰ) make the center Cd1(Ⅱ) ion form a distorted octahedral geometry [CdN₄O₂] (Fig. 3). The bond lengths of Cd1-N2, Cd1-N3 and Cd1-O2 are 0.248 9(2), 0.238 9(2) and 0.245 4(2), respectively. The Cd-N bond lengths are within the normal ranges observed for the 1, 3, 4-oxadiazole based Cd(Ⅱ) complex^[17].

  Figure 3

  

  Figure 3.  (a) Structure of 2 with atomic labeling; (b) Hydrogen bond and π…π interactions in 2; (c) 3D structure of 2

  Symmetry codes: ^ⅰ2-x, y, 3/2-z; ^ⅱ3/2-x, 1/2+y, 3/2-z; ^ⅲ-1/2+x, 1/2-y, -1/2+z; ^ⅳ5/2-x, 1/2-y, 1-z

  下载: 全尺寸图片 幻灯片

  In complex 2, there are three non-classical intermolecular hydrogen bonding interactions: C1-H1C…O2^ⅱ, C5-H5…O2^ⅲ and C7-H7…O3^ⅳ (Table 5 and Fig. 3). In addition, the pyridyl rings involve a face-to-face π…π interaction with a centroid-centroid distance of 0.391 01(19) nm. All these interactions link the complex 2 molecules into a three-dimensional network structure.

  Table 5

  

  Table 5.  Hydrogen bond and π…π interactions for 2

  下载: 导出CSV

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C1-H1C…O2ⅱ	0.096 05	0.255 58	0.342 2(5)	150.02
  C5-H5…O2ⅲ	0.093 07	0.241 18	0.330 8(4)	161.60
  C7-H7…O3ⅳ	0.092 97	0.250 81	0.339 8(4)	160.46
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg2…Cg2ⅴ			0.391 1(2)	0.02
  Cg2: N3, C4, C5, C6, C7, C8; Symmetry codes:ⅱ3/2-x, 1/2+y, 3/2-z; ⅲ-1/2+x, 1/2-y, -1/2+z; ⅳ5/2-x, 1/2-y, 1-z; ⅴ2-x, 1-y, 1-z.

  2.2   Spectral characterization

  In the IR spectrum of L (Fig. 4), the bands of 1 578, 1 553 and 1 454 cm^-1 are attributed to the aromatic rings stretching vibrations of pyridine and 1, 3, 4-oxadiazole. As the nitrogen atoms coordinate to the central Cu(Ⅱ) or Cd(Ⅱ) ions in complexes 1 and 2, the corresponding absorption bands are blue-shifted. In the spectra of 1 and 2, absorption bands at 1 600 cm^-1 (or 1 583 cm^-1), 1 575 cm^-1 (or 1 567 cm^-1) and 1 488 cm^-1 (or 1 492 cm^-1) are observed, which are assigned to the aromatic rings stretching vibrations. This indicates that the Cu1(Ⅱ) and Cd1(Ⅱ) ions are coordinated by nitrogen atoms from oxadiazole and pyridine rings. In complex 2, the bands of 1 289 cm^-1 are attributed to NO₃^-.

  Figure 4

  

  Figure 4.  IR spectra of L, 1 and 2

  下载: 全尺寸图片 幻灯片

  The UV-Vis spectra of L is given in Fig. 5(a). Maximum absorption peak appears at 240 and 276 nm, which are attributed to the π-π^* and n-π^* transitions, respectively. The fluorescence property of L has been examined in ethanol solution at room temperature. The fluorescence spectrum is shown in Fig. 5(b), which shows L is fluorescent. Maximum emission peak and excitation wavelength is 403 and 250 nm, respectively, which is attributed to π-π^* electronic transition^[27].

  Figure 5

  

  Figure 5.  IR, UV-Vis and fluorescence spectra of L

  下载: 全尺寸图片 幻灯片

  In the UV-Vis spectra of 1 and 2, the maximum absorption peak of 1 appears at 240.04 nm and 275.09 nm, and those for 2 appear at 240.13 nm and 276.05 nm. This is attributed to π-π^* and n-π^* transitions. The fluorescence properties of complexes 1 and 2 have been examined in methanol solution at room temperature, but no fluorescence properties were observed.

  2.3   Thermal gravimetric analysis

  Thermal gravimetric analyses (TGA) of complexes 1 and 2 were accomplished in nitrogen atmosphere with the heating rate of 10 K·min^-1. The TGA curves of complexes 1 and 2 are presented in Fig. 6. When the temperature is below 95 ℃, complex 1 is stable. Complex 1 decomposed gradually with the temperature raised between 95 and 800 ℃. Total weight loss was close to 71.00% at 800 ℃. The final residue is CuO (Calcd. 26.9%). Complex 2 is stable below 150 ℃. Complex 2 decomposed sharply with the temperature raised between 200 and 300 ℃. When the temperature reached to 650 ℃, total weight loss is close to 80.97% (Calcd. 77.02%).

  Figure 6

  

  Figure 6.  TGA curves for complexes 1 and 2

  下载: 全尺寸图片 幻灯片

  3.   Conclusions

  Ligand L, complexes 1 and 2 were synthesized and characterized. The free ligand L exhibits fluorescence. Complex 1 is a double-bridged binuclear Cu(Ⅱ) complex. Two copper(Ⅱ) ions are bridged by two Cl atoms, and the central copper(Ⅱ) ions have distorted tetragonal geometries [CuCl₃N₂]. In complex 2, the central Cd(Ⅱ) ion have a distorted octahedral geometry [CdN₄O₂].

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

• 1. [1]

     Holla B S, Gonsalves R, Shenoy S. Eur. J. Med. Chem., 2000, 35:267-271 doi: 10.1016/S0223-5234(00)00154-9

  2. [2]

     Boström J, Hogner A, Llinas A, et al. J. Med. Chem., 2012, 55:1817-1830 doi: 10.1021/jm2013248

  3. [3]

     Ishii M, Jorge S D, de Oliveira A A, et al. Bioorg. Med. Chem., 2011, 19:6292-6301 doi: 10.1016/j.bmc.2011.09.009

  4. [4]

     Bhandari S V, Parikh J K, Bothara K G, et al. J. Enzyme Inhib. Med. Chem., 2010, 25:520-530 doi: 10.3109/14756360903357585

  5. [5]

     刘建超, 王卫东, 贺红武.有机化学, 2014, 34(7):1447-1457 http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yjhx201407023LIU Jian-Chao, WANG Wei-Dong, HE Hong-Wu. Chinese J. Org. Chem., 2014, 34(7):1447-1457 http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yjhx201407023

  6. [6]

     Banerjee A G, Das N, Shengule S A, et al. Eur. J. Med. Chem., 2015, 101:81-95 doi: 10.1016/j.ejmech.2015.06.020

  7. [7]

     Ilango K, Valentina P, Kumar G, et al. Med. Chem., 2015, 11:753-763 doi: 10.2174/1573406411666150519112037

  8. [8]

     Verma G, Chashoo G, Ali A, et al. Bioorg. Chem., 2018, 77:106-124 doi: 10.1016/j.bioorg.2018.01.007

  9. [9]

     Dewangan, D, Verma V S, Nakhate K T, et al. Med. Chem. Res., 2016, 25:2143-2154 doi: 10.1007/s00044-016-1641-8

  10. [10]

      Wang B L, ZhuH W, Ma Y, et al. J. Agric. Food. Chem., 2013, 61:5483-5493 doi: 10.1021/jf4012467

  11. [11]

      Adachi C, Tokito S, Tsutsui T, et al. Jpn. J. Appl. Phys., 1988, 28:L269-L271

  12. [12]

      Bouanis M, Tourabi M, Nyassi A, et al. Appl. Surf. Sci., 2016, 389:952-966 doi: 10.1016/j.apsusc.2016.07.115

  13. [13]

      Gurudatt D M, Mohana K N. Ind. Eng. Chem. Res., 2014, 53:2092-2105 doi: 10.1021/ie402042d

  14. [14]

      Raj X J, Rajendran N. Prot. Met. Phys. Chem. Surf., 2013, 49:763-775 doi: 10.1134/S2070205113060257

  15. [15]

      Mohamed N A. Polym. Degrad. Stab., 2017, 146:42-45 doi: 10.1016/j.polymdegradstab.2017.09.017

  16. [16]

      Shavaleev N M, Scopelliti R, Gratzel M, et al. Inorg. Chim. Acta, 2013, 394:295-299 doi: 10.1016/j.ica.2012.07.026

  17. [17]

      Bharty M K, Bharti A, Dani R K, et al. J. Mol. Struct., 2012, 1011:34-31 doi: 10.1016/j.molstruc.2011.12.015

  18. [18]

      Slyvka Y, Goreshnik E, Veryasov G, et al. Polyhedron, 2017, 133:319-326 doi: 10.1016/j.poly.2017.05.052

  19. [19]

      Bharty M K, Dani R K, Nath P, et al. Polyhedron, 2015, 98:84-95 doi: 10.1016/j.poly.2015.05.045

  20. [20]

      Garcia A, Machado R C, Grazul R M, et al. J. Biol. Inorg. Chem., 2016, 21:275-292 doi: 10.1007/s00775-016-1338-y

  21. [21]

      Chaves J D S, Tunes L G, Franco C H D J, et al. Eur. J. Med. Chem., 2017, 127:727-739 doi: 10.1016/j.ejmech.2016.10.052

  22. [22]

      Gallego B, Kaluderovic M R, Kommera H, et al. Invest. New Drugs, 2011, 29:932-944 doi: 10.1007/s10637-010-9449-8

  23. [23]

      Köhler C, Rentschler E. Eur. J. Inorg. Chem., 2016, 13-14:1955-1960 doi: 10.1002/ejic.201501278/pdf

  24. [24]

      James C A, Poirier B, Grise C, et al. Tetrahedron Lett., 2006, 47:511-514 doi: 10.1016/j.tetlet.2005.11.057

  25. [25]

      Sheldrick G M. Acta Crystallogr. Sect. A, 2008, A64:112-122

  26. [26]

      Li Y, Zhang C G, Cai L Y. J. Coord. Chem., 2013, 66:3100-3112 doi: 10.1080/00958972.2013.826350

  27. [27]

      盛俊峰, 王宁, 蔡良英, 等.无机化学学报, 2015, 31(2):405-412 http://qikan.cqvip.com/article/detail.aspx?id=663728357SHENG Jun-Feng, WANG Ning, CAI Liang-Ying, et al. Chinese J. Inorg. Chem., 2015, 31(2):405-412 http://qikan.cqvip.com/article/detail.aspx?id=663728357

• 

  Figure 1  (a) Structure of L with atomic labeling; (b) 2D structure of L linked by hydrogen bond and π…π interactions

  Symmetry codes: ^ⅰ2-x, -1/2+y, 1/2-z; ^ⅱ1-x, 2-y, -z; ^ⅲ2-x, 1/2+y, 1/2-z

  下载: 全尺寸图片 幻灯片
  

  Figure 2  (a) Structure of 1 with atomic labeling; (b) 2D structure of 1 through the hydrogen bond interactions; (c) 3D structure of 1 linked by hydrogen bond and π…π interactions

  Symmetry codes: ^ⅰ2-x, 1-y, 1-z; ^ⅱ2-x, 1-y, -z; ^ⅲ-1+x, -1+y, -1+z

  下载: 全尺寸图片 幻灯片
  

  Figure 3  (a) Structure of 2 with atomic labeling; (b) Hydrogen bond and π…π interactions in 2; (c) 3D structure of 2

  Symmetry codes: ^ⅰ2-x, y, 3/2-z; ^ⅱ3/2-x, 1/2+y, 3/2-z; ^ⅲ-1/2+x, 1/2-y, -1/2+z; ^ⅳ5/2-x, 1/2-y, 1-z

  下载: 全尺寸图片 幻灯片
  

  Figure 4  IR spectra of L, 1 and 2

  下载: 全尺寸图片 幻灯片
  

  Figure 5  IR, UV-Vis and fluorescence spectra of L

  下载: 全尺寸图片 幻灯片
  

  Figure 6  TGA curves for complexes 1 and 2

  下载: 全尺寸图片 幻灯片

  Table 1.  Crystal data and structure refinement for L, 1 and 2

  Compound	L	1	2
  Formula	C8H7N3O	C8H7Cl2CuN3O	C8H7Cd0.5O4
  Formula weight	161.17	295.61	279.38
  Crystal system	Monoclinic	Triclinic	Monoclinic
  Space group	P21/c	P1	C2/c
  a/nm	0.786 3(8)	0.826 4(5)	1.090 0(3)
  b/nm	1.069 6(11)	0.851 7(5)	1.384 4(4)
  c/nm	0.938 9(10)	0.901 1(8)	1.362 3(4)
  α/(°)		109.627(8)
  β/(°)	99.344(13)	113.387(8)	99.090(4)
  γ/(°)		99.513(6)
  (V/nm3	0.779 1(14)	0.514 6(6)	2.029 9(11)
  Z	4	2	8
  Dc/(g·cm3)	1.374	1.908	1.828
  θ range/(°)	2.63-26.00	2.71-25.50	2.40-25.79
  μ/mm-1	0.096	2.613	1.141
  F(000)	336	294	1112
  Rint	0.027 9	0.021 9	0.033 3
  Reflection collected	5 584	3 752	7 223
  Independent reflection	1 506	1 881	1 933
  Observed reflection	1 188	1 771	1 682
  Data, restrain, parameter	1 506, 0, 111	1 881, 0, 138	1 933, 2, 151
  Goodness-of-fit on F2	1.050	1.091	1.108
  R1, wR2 [I > 2σ(I)]	0.038 2, 0.100 4	0.023 0, 0.062 5	0.028 0, 0.060 8
  R1, wR2 (all data)	0.049 3, 0.107 1	0.024 5, 0.063 1	0.034 6, 0.062 6
  (Δρ)max, (Δρ)min/(e·nm-3)	183, -107	337, -313	361, -320

  下载: 导出CSV

  Table 2.  Selected bond lengths (nm) and bond angles (°) for L, 1 and 2

  L
  C2-N1	0.128 26(19)	C3-O1	0.135 68(18)	N1-N2	0.140 7(2)
  C2-O1	0.136 59(17)	C3-N2	0.128 9(2)
  N1-C2-O1	112.36(14)	C3-O1-C2	102.77(11)	C3-N2-N1	106.30(10)
  N2-C3-O1	112.32(11)	C2-N1-N2	106.25(12)
  1
  Cu1-Cl1	0.272 52(13)	Cu1-Cl2	0.223 29(16)	Cu1-N3	0.210 2(3)
  Cu1-C11ⅰ	0.226 86(10)	Cu1-N2	0.202 5(2)
  N2-Cu1-N3	79.18(10)	N3-Cu1-Cl2	166.14(6)	Cl2-Cu1-Cl1	101.89(4)
  N2-Cu1-Cl2	93.43(9)	N3-Cu1-C11ⅰ	91.19(8)	Cl1-Cu1-Cl1ⅰ	90.89(5)
  N2-Cu1-C11ⅰ	168.72(6)	N3-Cu1-Cl1	90.50(6)
  N2-Cu1-Cl1	95.00(7)	Cl2-Cu1-Cl1ⅰ	94.76(7)
  2
  Cd1-N2	0.248 9(2)	Cd1-02	0.245 4(2)	Cd1-O3	0.247 9(2)
  Cd1-N3	0.238 9(2)
  N3ⅰ-Cd1-N3	113.98(12)	N3-Cd1-N2	68.93(8)	O2ⅰ-Cd1-N2ⅰ	154.16(7)
  N3-Cd1-O2ⅰ	104.18(8)	N2ⅰ-Cd1-N2	130.77(11)	O2ⅰ-Cd1-O2	80.72(10)
  N3-Cd1-O2	125.82(7)	O2-Cd1-N2ⅰ	74.61(7)
  N3-Cd1-N2ⅰ	84.59(8)	O2-Cd1-N2	154.16(8)
  Symmetry codes: ⅰ2-x, 1-y, 1-z for 1; ⅰ2-x, y, 3/2-z for 2.

  下载: 导出CSV

  Table 3.  Hydrogen bond and π…π interactions for align="left"

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C1-H1A …N2ⅰ	0.095 94	0.255 21	0.349 7(4)	168.40
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg1…Cg2ⅱ			3.891(4)	10.66
  Cg1: O1, C2, N1, N2, C3; Cg2: N3, C4, C5, C6, C7, C8; Symmetry codes: ⅰ2-x, -1/2+y, 1/2-z; ⅱ1-x, 2-y, -z.

  下载: 导出CSV

  Table 4.  Hydrogen bond and π…π interactions for 1

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C8-H8…C11ⅰ	0.093 05	0.268 37	0.324 2(4)	119.30
  C5-H5…C11ⅱ	0.092 97	0.270 21	0.352 8(4)	148.46
  C7-H7…C12ⅲ	0.092 95	0.273 53	0.365 5(5)	170.21
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg3…Cgⅱ			0.3874(4)	2.41
  Cg4…Cg4ⅳ			0.3629(4)	0.00
  Cg3: O1, C2, N1, N2, C3; Cg4: N3, C4, C5, C6, C7, C8; Symmetry codes: ⅰ2-x, 1-y, 1-z; ⅱ2-x, 1-y, -z; ⅲ-1+x, -1+y, -1+z; ⅳ1-x, 1-y, -z.

  下载: 导出CSV

  Table 5.  Hydrogen bond and π…π interactions for 2

  D-H…A	d(D-H)/nm	d(H…A)/nm	d(D…A)/nm	∠DHA/(°)
  C1-H1C…O2ⅱ	0.096 05	0.255 58	0.342 2(5)	150.02
  C5-H5…O2ⅲ	0.093 07	0.241 18	0.330 8(4)	161.60
  C7-H7…O3ⅳ	0.092 97	0.250 81	0.339 8(4)	160.46
  			d(Cg-Cg)/nm	Dihedral angle/(°)
  Cg2…Cg2ⅴ			0.391 1(2)	0.02
  Cg2: N3, C4, C5, C6, C7, C8; Symmetry codes:ⅱ3/2-x, 1/2+y, 3/2-z; ⅲ-1/2+x, 1/2-y, -1/2+z; ⅳ5/2-x, 1/2-y, 1-z; ⅴ2-x, 1-y, 1-z.

  下载: 导出CSV
•