MIAO Shao-Bin WANG Yu-Fang DENG Dong-Sheng XU Chun-Ying LI Zhao-Hao JI Bao-Ming

?

Two Co(II) Coordination Polymers Based on 3,5-Di(4H-1,2,4-triazole-4-yl)benzoic Acid Ligand: Syntheses, Structures and Magnetic Property①

MIAO Shao-Bin WANG Yu-Fang DENG Dong-Sheng XU Chun-Ying LI Zhao-Hao JI Bao-Ming②

(471022)

Two Co(II) coordination polymers, namely [Co(L)Cl](1) and [Co(L)(CH3COO)](2), {HL = 3,5-di(4H-1,2,4-triazole-4-yl)benzoic acid}, were synthesized under hydrothermal conditions. Compound 1 crystallizes in orthorhombic system, space groupwith= 7.032(5),= 11.555(8),= 8.185(5) ?,= 665.1(7) ?3,= 2,D= 1.746 g/cm3,(000) = 350,M= 349.61,= 1.504 mm-1, the final= 0.0568 and= 0.1739 for 2312 observed reflections with> 2(). Compound 2 crystallizes in orthorhombic system, space groupwith= 7.7505(17),= 11.391(3),= 8.0298(18) ?,= 708.9(3) ?3,= 2,D= 1.748 g/cm3,(000) = 378,M= 373.20,= 1.245 mm-1, the final= 0.0350 and= 0.0873 for 5239 observed reflections with> 2(). Single-crystal X-ray analyses revealed that complexes 1 and 2 exhibit similar 2layer structures with uncoordinated carboxyl as dangling arms. The neighboring layers are further connected by these arms, leading to interest 2→ 3polythreading frameworks. Moreover, the magnetic susceptibility study indicates compound 1 exhibits antiferromagnetic behavior.

coordination polymer, 3,5-di(4H-1,2,4-triazole-4-yl)benzoic acid, crystal structure, magnetic property;

1 INTRODUCTION

Coordination polymers (CPs) or organic-inorga- nic hybrid materials, constructed by inorganic secondary building units (SBUs) and organic bridging ligands, have taken wide attention in recent years owing to their intriguing structural as well as distinctive properties such as catalytic, lumine- scence, gas adsorption, and magnetism[1–7]. The physicochemical properties of the coordination polymers are mainly determined by the structural features like porosities, dimensionalities, pore shapes, pore sizes, and surface areas[8–13]. It is well known that a reasonable selection of organic ligands may lead to desired coordination networks. The most widely used building ligands are benzenecarb- oxylic acids and N-containing heterocyclic com- pounds in the construction of CPs[14–19]. More recently, bifunctional ligands containing carboxy- late groups and nitrogen donors have attracted great interests[20–25]. As an ideal bifunctional ligand, 3,5-di(4H-1,2,4-triazole-4-yl)benzoic acid (HL) can adopt versatile coordination modes, resulting in diverse architectures. Unfortunately, only limited HL-based CPs so far have been reported[26–28]. Most of these CPs exhibit 2layer structures. Even aromatic multicarboxylic acids were used as mixed ligands. On the other hand, only a few properties have been studied about these CPs. Hence, it is still necessary to construct more CPs of HL as well as explore their novel properties. With these consi- derations in mind, we would like to report herein the syntheses and structures of two new 2Co(II) CPs based on HL, [Co(L)Cl](1) and [Co(L)(CH3COO)](2). The magnetic properties of complex 1 also have been investigated.

2 EXPERIMENTAL

All chemicals and solvents used were purchased commercially and used without further purification. HL was prepared by the literature method[27]. Elemental analyses (C, H, N) were performed with a Flash 1112 elemental analyzer. Infrared spectra for solid samples were recorded on a Nicolet Avatar- 360 FTIR spectrometer in the 400～4000 cm–1region. Powder X-ray diffraction (PXRD) data were collected on a Bruker AXS D8-Advanced X-ray powder diffractometer with Cu-radiation (= 1.5460 ?). Variable-temperature magnetic suscepti- bility was performed on a MPMSXL-7 SQUID magnetometer.

2. 1 Syntheses of compounds 1 and 2

Compound 1 A mixture of CoCl2·6H2O (0.1 mmol, 23.8 mg), HL (0.1 mmol, 25.6 mg), and H2O (10 mL) was sealed in a 25 mL Teflon-lined stainless-steel vessel. The mixture was heated at 170 ℃ for 4 days and then slowly cooled down to room temperature at a rate of 3 ℃/h. Red block crystals of 1 were obtained in 43% yield based on Co(II). Anal. Calcd. for C11H7ClCoN6O2: C, 37.79; H, 2.02; N, 24.04%. Found: C, 37.53; H, 2.08; N, 24.15%. IR (KBr, cm–1): 3012(), 2959(), 1617(), 1540(), 1312(), 1212(), 1008(), 897(), 728(), 691().

Compound 2 A mixture of Co(Ac)2·4H2O (0.1 mmol, 24.9 mg), HL (0.1 mmol, 25.6 mg), and H2O (10 mL) was sealed in a 25 mL Teflon-lined stainless-steel vessel. The mixture was heated at 120 ℃ for 3 days and then slowly cooled down to room temperature at a rate of 3 ℃/h. Red block crystals of 2 were obtained in 54% yield based on Co(II). Anal. Calcd. for C13H10CoN6O4: C, 41.84; H, 2.70; N, 22.52%. Found: C, 41.62; H, 2.77; N, 22.71%. IR (KBr, cm–1): 3091(), 3012(), 1647(), 1581(), 1311(), 1212(), 1006(), 894(), 724(), 668().

2. 2 X-ray structure determination

X-ray diffractions were collected on a Bruker SMART APEX II CCD diffractometer with a gra- phite-monochromated Moradiation (= 0.71073 ?) at room temperature. A total of 2312 reflections were collected for 1, of which 701 (int= 0.0758) independent reflections were collected at 296(2) K. A total of 5239 reflections were collected at 296(2) K for 2, of which 752 (int= 0.0626) were indepen- dent. The absorption corrections were based on multiple and symmetry-equivalent reflections in the data set using the SADABS program. The structures were solved by direct methods with SHELXS-97[29]and refined by the least-squares methods with SHELXL-97 program[30]. All non-hydrogen atoms were refined anisotropically, and the hydrogen atoms were added to their calculated positions and refined using a riding model. The selected bond lengths and bond angles are listed in Table 1.

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

Symmetry codes: #1: –+1, –+1, –+1; #2:, –+1,; #3:+1,, –+1; #4: –, –, –; #5: –,, –; #6:, –,

3 RESULTS AND DISCUSSION

3. 1 Crystal structure description

Compound 1 crystallizes in the orthorhombic system with space group. The fundamental unit of 1 contains one Co(II) ion, one L–ligand, and one coordinated Cl–ion. As shown in Fig. 1a, the Co(II) ion is six-coordinated and surrounded by four nitrogen atoms from four individual L–ligands and two Cl–ions, giving a slightly distorted octahedron geometry with Co–N bond distance of 2.115 (4) ? and the Co–Cl bond length of 2.395(4) ?. Each Cl–ion acts as a2-bridging ligand to link two Co(II) atoms to give rise to an infinite 1(CoCl)chain along theaxis. Neighboring chains are further linked by L–ligands in a4-1:1:1:1mode to furnish a 2layer structure (Fig. 1b). Interestingly, in each layer, the uncoordinated carboxyl groups of L–are all out of the layer as dangling arms (Fig. 1c), by which adjacent layers are threaded each other, leading to an unusual 2→ 3polythreading framework[31](Fig. 1d).

Fig. 1. (a) Coordination environment of Co(II) ion in 1.Symmetry codes: #1: 1 –, 1 –, 1 –; #2:, 1 –,;#3: 1 –,, 1 –; #4: 1.5 –,,;#5: 1.5 –, 2 –,;#6:, 2 –,. (b) View of the 2layer structure of 1.(c) View of the 2structure of 1 with dangling arms. (d) View of the 2→ 3polythreading frameworkof 1. All H atoms are omitted for clarity

Complex 2 has a similar 2→3polythreading framework to that of complex 1 except that CH3COO–ions instead of Cl–ions as bridging ligands to construct the 1chain. Complex 2 crystallizes in the orthorhombic space group. There exist one Co(II) ion, one L–anion, and one coordinated CH3COO–ion in the asymmetric unit (Fig. 2a). The Co(II) atom also shows a slightly distorted octahedral geometry, coordinated by four nitrogen atoms from four L–anions and two oxygen atoms from two CH3COO–ions. The bond lengths of Co–N and Co–O are 2.1314(14) and 2.0496(17) ?, respectively. The Co–N bond length is slightly longer than that in complex 1, which may be caused by the larger space steric hindrance of CH3COO–ion. In complex 2, CH3COO–ions act as a2-bridging ligand to link Co(II) atoms into 1chains, then the chains are further connected by L–ligands to furnish 2layers (Fig. 2b). The adjacent layers are threaded each other by uncoordinated carboxyl groups of L–(Fig. 2c) to give the final 2→ 3polythreading framework (Fig. 2d).

Fig. 2. (a) Coordination environment of Co(II) ion in 2.Symmetry codes: #1: –, –, –; #2: –,, –; #3:, –,; #4: 0.5 –,,;#5: 0.5 –, 1 –,;#6:, 1 –,;#7: 0.5 –, –,. (b) View of the 2layer structure of 2. (c) View of the 2structure of 2 with dangling arms. (d) View of the 2→ 3polythreading frameworkof 2. All H atoms are omitted for clarity

3. 2 Powder X-ray diffraction

Powder X-ray diffraction (PXRD) experiments at room temperature were carried out to investigate the purities of compounds 1 and 2 (Fig. 3). The main peaks observed match well with the simulated ones, indicating the phase purities of the as-synthesized samples.

Fig. 3. Simulated and experimental powder X-ray diffraction patterns of compounds 1 (a) and 2 (b)

3. 3 Magnetic property of 1

Temperature dependent magnetic measurement of 1 was measured from 1.8 to 300 K in a magnetic field of 1000 Oe (Fig. 4a). The χTvalue of 2.06 cm3×K×mol–1at room temperature is much higher than the expected spin-only value of 1.875 cm3×K×mol–1for an uncoupled Co(II) (= 3/2,= 2.0), which can be attributed to spin-orbital coupling interaction. Upon cooling, theχTvalue decreases to reach a value of about 0.13 cm3/mol K at 1.8 K, indicating an antiferromagnetic interaction between the Co(II) cations. As shown in Fig. 4b, The 1/χdata above 50 K follow the Curie-Weiss law well with the Curie constantand Weiss constantof 0.9764 cm3×K×mol-1and –59.8034 K, respectively, indicating weak antiferromagnetic interactions between the Co(II) centers[32]. Since the (CoCl)chain is the dominant magnetic unit, an infinite chain model with Eq. 1 is used to fit the experi- mental magnetic susceptibilities of 1. The best fitting parameters are= 2.17,= –6.12 cm–1,= –0.03 cm–1, and= 1.97 × 10–3. The largervalue may be caused by the orbital contributions[33]. Thevalue shows weak antiferromagnetic coupling between the intrachain neighboring Co(II) ions.

= coth[JS(S+1)/KT]-KT/JS(S+1)

Fig. 4. (a) Temperature dependence of magnetic susceptibilities in the forms ofM(○) andM(□) against T plots for

compound 1. (b) 1/χm data above 50 K following the Curie-Weiss law

4 CONCLUSION

In summary, two new Co(II) CPs based on a triazole-carboxyl-bifunctional ligand have been hydrothermally synthesized, which perform unusual 2→3polythreading frameworks. The magnetic analysis shows the antiferromagnetic interactions between the Co(II) ions in compound 1. Further studies on the design and syntheses of other transition metal ions based CPs with HL are in progress.

(1) Foo, M. L.; Matsuda, R.; Hijikata, Y.; Krishna, R.; Sato, H.; Horike, S.; Hori, A.; Duan, J.; Sato, Y.; Kubota, Y.; Takata, M.; Kitagawa, S. An adsorbate discriminatory gate effect in a flexible porous coordination polymer for selective adsorption of CO2over C2H2.. 2016, 138, 3022–3030.

(2) Kurmoo, M. Magnetic metal-organic frameworks.. 2009, 38, 1353–1379.

(3) Li, J. R.; Kuppler, R. J.; Zhou, H. C. Selective gas adsorption and separation in metal-organic frameworks.. 2009, 38, 1477–1504.

(4) Allendorf, M. D.; Bauer, C. A.; Bhakta, R. K.; Houk, R. J. T. Luminescent metal-organic frameworks.. 2009, 38, 1330–1352.

(5) Janiak, C. Engineering coordination polymers towards applications.. 2003, 14,2781–2804.

(6) Wu, C. D.; Hu, A. G.; Zhang, L.; Lin, W. B. A homochiral porous metal-organic framework for highly enantioselective heterogeneous asymmetric catalysis.. 2005, 127, 8940–8941.

(7) Wang, H. S.; Yang, F. J.; Long, Q. Q.; Huang, Z. Y.; Chen, W.; Pan, Z. Q.; Song, Y. Two unprecedented decanuclear heterometallic [Mn2IIMn6IIILn2III] (Ln = Dy, Tb) complexes displaying relaxationg of magnetization.. 2016, 45, 18221–18228.

(8) Maity, K. K.; Halder, A.; Bhattacharya, B.; Das, A.; Ghoshal, D. Selective CO2adsorption by nitro functionalized metal-organic frameworks.. 2016, 16, 1162–1167.

(9) Biswas, S.; Mondal, A. K.; Konar, S. Densely packed lanthanide cubane based 3metal-organic frameworks for efficient magnetic refrigeration and slow magnetic relaxation.. 2016, 55, 2085–2090.

(10) Gole, B.; Sanyal, U.; Banerjee, R.; Mukherjee, P. S. High loading of Pd nanoparticles by interior functionalization of MOFs for heterogeneous catalysis.. 2016, 55, 2345–2354.

(11) Foo, M. L.; Matsuda, R.; Hijikata, Y.; Krishna, R.; Sato, H.; Horike, S.; Hori, A.; Duan, J.; Sato, Y.; Kubota, Y.; Takata, M.; Kitagawa, S. An adsorbate discriminatory gate effect in a flexible porous coordination polymers for selective adsorption of CO2over C2H2.. 2016, 138, 3022–3030.

(12) Kitagawa, S.; Kitaura, R.; Noro, S. Functional porous coordination polymers.. 2004, 43, 2334–2375.

(13) Chen, Y. Z.; Chen, X. L.; Chen, Y. F.; Jia, L. H.; Zeng, M. H. Design, structure and magnetic properties of a novel one-dimensional Mn(II) coordination polymer constructed from 4-pyridyl-NH-1,2,3-triazole.. 2017, 84, 182–185.

(14) He, Y. P.; Tan, Y. X.; Zhang, J. Stable Mg-metal-organic framework (MOF) and unstable Zn-MOF based on nanosized tris((4-carboxyl)phenyldury)

amine ligand.. 2013, 13, 6–9.

(15) Banerjee, D.; Parise, J. B. Recent advances in s-block metal carboxylate networks.. 2011, 11, 4704–4720.

(16) Wan, X. Y.; Jiang, F. L.; Chen, L.; Pan, J.; Zhou, K.; Su, K. Z.; Pang, J. D.; Lyu, G. X.; Hong, M. C. Structural variability, unusual thermochromic luminescence and nitrobenzene sensing properties of five Zn(II) coordination polymers assembled from a terphenyl-hexacarboxylate ligand.2015, 17, 3829–3837.

(17) Wu, H.; Yang, J.; Su, Z. M.; Batten, S. R.; Ma, J. F. An exceptional 54-fold interpenetrated coordination polymer with 103-srs network topology.. 2011, 133, 11406–11409.

(18) Bai, S. Q.; Jiang, L.; Sun, B.; Young, D. J.; Hor, T. S. A. Five Cu(I) and Zn(II) clusters and coordination polymers of 2-pyridyl-1,2,3-triazoles: synthesis, structures and luminescence properties.2015, 17, 3305–3311.

(19) Cai, S. L.; Huang, Y.; Gao, Y.; Fan, J.; Zheng, S. R.; Zhang, W. G. Temperature/anion-dependent self-assembly of Co(II) coordination polymers based on a heterotopic imidazole-tetrazole-bifunctional ligand: structures and magnetic properties.. 2017, 84, 10–14.

(20) Cui, H. H.; Lin, C. S.; Shen, N. N.; Huang, X. Y. A novel heterometallic BaGa coordination polymer based on the bifunctional ligand 2,5-pyridine dicarboxylic acid.. 2016, 70, 86–89.

(21) Zhang, X. T.; Fan, L. M.; Fan, W. L.; Li, B.; Liu, G. Z.; Zhao, X. A series of lanthanide coordination polymers based on designed bifunctional 1,4-bis(imidazol-1-yl)terephthalic acid ligand: structural diversities, luminescence, and magnetic properties.2016, 16, 3993–4004.

(22) Yang, L. B.; Wang, H. C.; Dou, A. N.; Rong, M. Z.; Zhu, A. X.; Yang, Z. Roles of anions in the structural diversity of Cd(II) complexes based on a V-shaped triazole-carboxylate ligand: Synthesis, structure and photoluminescence properties.2016, 446, 103–110.

(23) Li, G. P.; Liu, G.; Li, Y. Z.; Hou, L.; Wang, Y. Y.; Zhu, Z. H. Uncommon pyrazoyl-carboxyl bifunctional ligand-based microporous lanthanide systems: sorption and luminescent sensing properties.. 2016, 55, 3952–3959.

(24) Yang, L. B.; Wang, H. C.; Fang, X. D.; Chen, S. J.; Xu, Q. Q.; Zhu, A. X.; Yang, Z. A series of Zn(II) and Cd(II) coordination compounds based on 4-(4H-1,2,4-triazol-4-yl)benzoic acid: synthesis, structure and photoluminescence properties.2016, 18, 130–142.

(25) Wu, M. F.; Zheng, F. K.; Wu, A. Q.; Li, Y.; Wang, M. S.; Zhou, W. W.; Chen, F.; Guo, G. C.; Huang, J. S. Hydrothermal syntheses, crystal structures and luminescent properties of zinc(II) coordination polymers constructed by bifunctional tetrazolate-5-carboxylate ligands.2010, 12, 260–269.

(26) Liu, B.; Yu, Y. H.; Jiang, W. H.; Hou, G. F.; Gao, J. S. A new luminescent complex constructed by oxomolybdate and 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid via Mo–N bonds.. 2015, 54, 12–15.

(27) Jiang, W. H.; Liu, J. L.; Niu, L. Z.; Liu, B.; Yu, Y. H.; Hou, G. F.; Ma, D. S. Constructions and properties of zinc coordination polymers based on 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid with different polycarboxylic acids as a secondary ligand.2017, 124, 191–199.

(28) Jiang, W. H.; Liu, B.; Yu, Y. H.; Hou, G. F.; Ma, D. S. Syntheses, structures and properties of two coordination polymers based on 3,5-di(4H-1,2,4-triazol-4-yl)benzoic acid with multicarboxylates as mixed ligands.2017, 129, 208–213.

(29) Sheldrick, G. M.. University of G?ttingen: Germany 1997.

(30) Sheldrick, G. M.. University of G?ttingen: Germany 1997.

(31) Liu, Y. Y.; Liu, H. Y.; Ma, J. F.; Yang, Y.; Yang, J. Syntheses, structures and photoluminescent properties of Zn(II) and Cd(II) coordination polymers with flexible tripodal triazole-containing ligands.2013, 15, 1897–1907.

(32) Xiong, L. N.; Liu, Q. Y.; Wang, Y. L. Crystal structure and magnetic properties of a two-dimensional compound {(Me2NH2)4[Co(SIP)2]·2(DMF)·3(H2O)}.. 2016, 35, 1231–1237.

(33) Wang, Y. L.; Chen, L.; Liu, C. M.; Zhang, Y. Q.; Yin, S. G.; Liu, Q. Y. Field-induced slow magnetic relaxation and gas adsorption properties of a bifunctional cobalt(II) compound.. 2015, 54, 11362–11368.

17 November 2017;

9 March 2018 (CCDC 1572243 for 1 and 1572244 for 2)

① This work was supported by the National Natural Science Foundation of China (21372112)

. Professor, majoring in material chemistry. E-mail: lyhxxjbming@126.com

10.14102/j.cnki.0254-5861.2011-1894