Syntheses, Structures of A Cobalt (II) Metal-organic Framework Based on 2, 6-di (2’, 4’-dicarboxylphenyl)pyridine and 4, 4’-bis (imidazol-1-ylmethyl)biphenyl-ligands

Yenan WANG, Xiaoqing NIU, Bo LIU

Coconut Research Institute of Chinese Academy of Tropical Agricultural Sciences, Hainan Innovation Center of Academician Team, Wenchang 571339, China

Abstract [Objectives] The paper was to synthesize and describe a new 3D structure of a mew metal organic framework, and to provide new materials for the study of interdisciplinary. [Methods] A mixture of H4L=2, 6-di (2’, 4’-dicarboxylphenyl)pyridine, bimb=4, 4’-bis (imidazole-1-ylmethyl)biphenyl), Co (NO3)2·6H2O were added to the solution of DMF∶H2O=4∶2 and heated at 433 K for 4 d. [Results] Purple block crystals of the Co-compound were obtained (yield 83.6%, based on Co). [Conclusions] The crystal data are obtained as follows: C51H36Co2N7O9, Triclinic, P-1, a=9.916 (8) ?, b=15.926 (14) ?, c=15.945 (13) ?, α=113.913 (13) °, β=93.929 (9)°, γ=95.033 (3) °, V=2 278 (3)A3, Z=2, R=0.080 3 (6446), wR2=0.210 6 (10 370), T=296 K.

Key words Cobalt (II); Metal-organic framework; Crystal; Syntheses; Structure

1 Introduction

Over the past two decades, metal- organic frameworks (MOFs) as fascinating class of hybrid porous materials has become a very popular field in chemistry and molecular materials, and received extensive attention in many disciplines. They are becoming increasingly adopted in biomedicine[1-3], medicinal chemistry[4-5], and heterogeneous catalysis[6], because of their high surface area, pore volume, controllable structure, well-defined surface functionalities, and biocompatibility. However it is rare studied in the Plant Protection subject. In this paper, we synthetized a cobalt (II) metal-organic frameworks based on 2, 6-di (2’, 4’-dicarboxylphenyl)pyridine and 4, 4’-bis (imidazol-1-ylmethyl)biphenyl-ligands, as fluorescent carrier for the study of plant pathogen nucleic acid detection.

2 Materials and syntheses methods

The metal salt and the organic ligand were commercially available and used without further purification. A mixture of 2, 6-di (2’, 4’-dicarboxylphenyl)pyridine, 4, 4’-bis (imidazol-1-ylmethyl)biphenyl, Co (NO3)2·6H2O were added to the solution of DMF∶H2O=4∶2 and heated at 433 K for 4 d, then cooled to the room temperature. Finally, purple block crystals of the Co-compound were obtained (yield 83.6%, based on Co).

3 X-ray single crystal structural analysis

The diffraction data for the Co-MOF were collected on a Rigaku XtaLAB mini diffractometer with graphite mono-chromated Mo Ka radiation (λ=0.710 73?). The structure was solved by direct methods and refined based on F2by the full matrix least-squares methods using SHELXTL. Non-hydrogen atoms were refined anisotropically, and hydrogen atoms were located at their calculated positions. Hydrogen atoms were not included in the model. Data collection: 4; program (s) used to solve structure: ShelXT[7]; program (s) used to refine structure: SHELXL[8]; molecular graphics: Olex2; software used to prepare material for publication: Olex2[9].

4 Refinement

H atoms were inserted in idealized positions and refined using a riding model, with Uiso (H) values equal to 1.2 or 1.5 times the Ueq value of the atom to which it was bonded.

5 Result and analysis

Crystal data: C51H38Co2N7O9, Mr=1 010.74, Triclinic,P-1, Z=2, a=9.916 (8) ?, b=15.926 (14) ?, α=113.913 (13)°, c=15.945 (13) ?, β=93.929 (9)°, γ=95.033 (3)°, volume (?3)=2278 (3), 0.21×0.18×0.17 mm.

Data collection: Bruker SMART 1000 CCD diffractometer, 24229 Reflections collected, absorption correction: multi-scan[10], 10370 unique withI>2σ (I), Tmin=0.846, Tmax=0.874, Rint=0.097 5.

Refinement: R[reflections]=0.080 3, wR (F2)=0.210 6, R1 [I >2σ (I)]=0.080 3, R1 (all data)=0.130 5, wR2[I >2σ (I)]=0.181 5, wR2(all data)=0.210 6, S=1.043, Npar=659.

Single-crystal X-ray diffraction analysis indicated that the compound mentioned in the title crystallized in TriclinicP-1space group and featured a 3D pillar-layered framework. The asymmetric unit of the title structure consisted of two Co (II) ion, one and a half bimb and one H4L. As shown in Fig.1a, a pair of Co1 atoms were bridged by four carboxylate groups in syn-syn coordination mode to form a paddlewheel dinuclear [Co2(RCOO)4] unit with the Co1…Co1#1 (#1: -x+1, -y+1, -z) separation of 2.864 8 (23)?. Each L4-ligand coordinated with four Co (II) atoms through four different carboxylate groups, adopting μ2-η1∶η1, μ2-η1∶ η1, μ1-η0∶η1 and μ1-η1∶η1 modes coordination modes. The Co2 ion was five-coordinated with a distorted trigonal bipyramidal geometry, which was completed by three carboxylate oxygen atoms of two L4-ligands and two N atoms from two different bimb ligands. The Co-O and Co-N distances located in the ranges of 2.016 (4)-2.353 (5) and 2.022 (5)-2.052 (11)?, respectively. Every two L4-ligand joined one dinuclear [Co2(COO)4] SBUs which was linked by Co2 into 1D chain assembly structure (Fig.1b). It is remarkable that, each Co2 linked N in a bimb ligand, extending the above one-dimensional chain into a two-dimensional layered structure. Eventually, the bimb linked by Co1 connected the structure to generate a 3D pillar-layered framework (Fig.1c-1d).

Note: a. Coordination environment (hydrogen atoms were omitted for clarity, symmetry codes: # 1-x+1, -y+1, -z # 2 x, y+1, z # 3 x, y, z-1 # 6-x+2, -y+1, -z+1); b. One dimensional chain structure; c. Co2 links bimb ligand, extending the two-dimensional layered structure; d. Co1 links bimb, forming the 3D pillar-layered framework.

6 Supplementary materials

All esds (except the esd in the dihedral angle between two l.s. planes) were estimated using the full covariance matrix, distances, angles and torsion angles; correlations between esds in cell parameters were only used when they were defined by crystal symmetry. An approximate (isotropic) treatment of cell esds was used for estimating esds involving l.s. planes (Tables.1-3).

Table 1 Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (?2)

Table 2 Bond lengths [?] and angles [deg] for z.

Table 3 Atomic displacement parameters (?2)

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