научная статья по теме HYDROTHERMAL SYNTHESIS, CRYSTAL STRUCTURE OF TWO NEW COORDINATION POLYMER {[NI2(IMAZAMETH)2(4,4’-BIPY)] · (CLO4) · CH2OH · H2O}N AND [CU2(PDA)1.5(2,2-BIPY)2](H2O)5(NO3) Химия

КООРДИНАЦИОННАЯ ХИМИЯ, 2013, том 39, № 6, с. 348-355

УДК 541.49

HYDROTHERMAL SYNTHESIS, CRYSTAL STRUCTURE OF TWO NEW COORDINATION POLYMER {[Ni2(Imazameth)2(4,4'-Bipy)] • (ClO4) • CH2OH • H2O}n

AND [Cu2(PDA)1.5(2,2-Bipy)2](H2O)5(NO3)

© 2013 Z. Zhang and X. H. Yin*

College of Chemistry and Ecological Engineering, Guangxi University for Nationalities, Nanning, 530006 P.R. China

*E-mail: yxhphd@163.com Received September 9, 2011

Two new metal—organic coordination polymers framework formulated as [Cu2(PDA)i 5(2,2'-Bipy)2](H2O)5(NO3) (I) and {[Ni2(Imazameth)2(4,4'-Bipy)] • (ClO4) • CH2OH ■ H2O}n (II), where H2PDA = 1,4-phenylenedi-acetic acid, 2,2'-Bipy = 2,2'-bipyridine, Imazameth = (+/-)2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid, 4,4'-Bipy = 4,4'-bipyridine, have been prepared and characterized by spectral method (IR), elemental analysis and single crystal X-ray diffraction techniques. Complex I consists of one-dimensional ladder-like chains featuring binuclear unit in which the two Cu2+ ions have different coordination geometry: one is five-coordinated, the other is six-coordinated. Complex II is a new two-dimensional copper complex with the peculiarity of having the 4,4'-Bipy ligand and Imazameth ligand acting as bridge to form planar network polymer. Both I and II exist abundant hydrogen bonds. It is result in the formation of a supermolecular crystal, in which they seem to be effective in the stabilization of the structure.

DOI: 10.7868/S0132344X13050113

INTRODUCTION

The self-assembled construction of coordination polymers is of current interest in the field of supramo-lecular chemistry and crystal engineering, due to their intriguing network topologies and potential applications in functional materials, such as gas storage, selective catalysis, molecular separation and magnetism [1—5]. Construction of coordination polymers using metal ions and rigid organic ligands characterized a fruitful subclass of materials applicable in both the academic and business areas. As far as we know, selecting appropriate ligands is the most effective strategy in obtaining coordination polymers. As bridging ligands, carboxylates, especially multi-carboxylates, are of immense interest in the construction of polymeric coordination architectures not only because the fact that these polymers have a wide range of structural diversities and potential applications as porous materials and magnetic materials, but also because the multi-carbox-ylates are capable of functioning as hydrogen bond donors and/or acceptors [6]. 1,4-Phenylenediacetic acid (H2PDA) is a typical dicarboxylate. It has two flexible acetates, resulting in trans- and cis-configuration [7].

Much effort has been devoted to the synthesis [8, 9], crystal structure [10, 12] and catalysis [13, 14] of the compounds containing imidazolidinone during the last few years. One of them is (+/-)-2-(4,5-Dihydro-4-me-thyl-4-(1-methylethyl)-5-oxo-1H-Imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid (Imazameth), which

provides with efficient metal-chelating ability. The Imazameth contains a pyridine carboxylic acid and an imidazole ring, which are well-known versatile ligands. The pyridine carboxylic acid and its anion have been extensively used in the design of coordination compounds, due to a variety of its bonding ability and exhibiting strong hydrogen bonds [15, 17]. Imida-zole ring, which is one of the polydentate amine ligands, generally coordinates to metal ions using the N atoms as donors. Hydrogen bonding can play an important role in the stabilization of supramolecular systems both in solution and in the solid state; sometimes metal ions in such structure can also act as glues in holding the water cluster.

The reaction of H2PDA, 2.2'-Bipy with Cu(NO3)2 • 3H2O was carried out under open-air mild reaction conditions to obtain I. And the reaction of Imazameth, 4,4'-Bipy with Ni(ClO4)2 • 6H2O was carried out under hydrothermal conditions to obtain II. In this work, we reports synthesis, crystal structure, spectral analysis (IR), elemental analysis, thermal gravimetric analysis (TG).

EXPERIMENTAL

Materials and methods. All reagents and solvents employed were commercially available and used as received without further purication. Elemental analysis for C, H, and N was carried out on a PerkinElmer

2400 II elemental analyzer. The FT-IR spectrum was obtained on a PE Spectrum One FT-IR Spectrometer Fourier transform infrared spectroscopy in the 4000— 400 cm-1 regions, using KBr pellets. PerkinElmer Diamond TG/DTA thermal analyzer was used to record simultaneous TG curves in the static air atmosphere at a heating rate of 10 K min-1 in the temperature range 0-800°C using platinum crucibles.

Synthesis of complex I. H2PDA (0.09705 g, 0.5 mmol) and 2,2'-Bipy (0.07807 g, 0.5 mmol) were dissolved in the mixture of 15 mL N,N-dimethylformamide and 10 mL H2O. Then an aqueous solution of sodium hydroxide was added dropwise with stirring to adjust the pH value of the solution being 6. At last, 10 mL aqueous solution of Cu(NO3)2 • 3H2O (0.1206 g, 0.5 mmol) was input. The mixture was kept stirring for 6 h at 70°C and then filtered. The filtrate was kept at room temperature and a few days later X-ray quality blue block single crystals were obtained. The crystals were isolated, washed with ethanol and dried at room temperature. The yield was 70% based on Cu).

For C^H^N^^C^

anal.calcd., %: C, 47.78; H, 4.35; N, 7.96. Found, %: C, 47.71; H, 4.37; N, 7.93.

IR spectrum (v, cm-1): 3480 br, 3076 w, 1601 s, 1519 m, 1500 m, 1471 m, 1454 m, 1390 s, 1149 w, 1097 s, 851 m, 772 m, 736 m, 619 w.

Synthesis of complex II. A solution of Imazameth (0.3912 g, 1.5 mmol) in 10 mL ethanol was added dropwise with stirring at room temperature to a solution of Ni(ClO4)2 • 6H2O (0.1328 g, 0.5 mmol) in 5 mL water. The mixture was stirred at room temperature until it was homogeneous, and then added to a solution of 4,4'-Bipy (0.1608 g, 1 mmol) in 5 mL ethanol. Then the mixture was sealed in a 25 mL Teflon-lined stainless reactor, kept under autogenous pressure at 100°C for 48 h, and then slowly cooled to room temperature at a rate of 5°C per hour. After several days, green block crystals suitable for X-ray diffraction were separated and washed with distill water and dried at ambient temperature. The yield was 65% based on Ni.

For C21H30N4O10aNi

anal. calcd., %: C, 42.56; H, 5.10; N, 9.45. Found, %: C, 42.49; H, 5.06; N, 9.47.

IR spectrum (v, cm-1): 3392 m, 3063 w, 2973 m, 1755 s, 1608 m, 1526 v.s, 1481 s, 1107 s, 815 w, 622 w.

X-ray structure determination. Crystallographic data of complexes I and II were collected on a Bruker SMART CCD area detector at 298 K using graphite mono-chromated Mo^a radiation (X = 0.71073 A). Empirical absorption corrections were applied using the SADABS program [18]. The structure was solved by the direct method and refined by full-matrix least

squares on F2 using the SHELXTL program [19]. All non-hydrogen atoms were refined anisotronically. A summary of the crystallographic data and structure refinement of complexes I and II are shown in Table 1, selected bond lengths and angles are listed in Table 2 and hydrogen bonging geometry are given in Table 3.

Supplementary material has been deposited with the Cambridge Crystallographic Data Center (no. 1.822338 (I), no. 2.824696 II); deposit@ccdc.cam.ac.uk or http:// www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

The X-ray crystal structure determination of complex I reveals that the asymmetric unit contains two kinds of metal environments (Fig. 1). Cu(1) ion is five-coordinated by two nitrogen atoms N(1), N(2) from one chelating 2,2'-Bipy ligand and three oxygen atoms O(1), O(3), O(5) from three PDA ions. Cu2+ ion is six-coordinated by two nitrogen atoms N(3), N(4) from one chelating 2,2'-Bipy ligand and four oxygen atoms O(1), O(2), O(3), O(6) from three PDA ions. The Cu-N bond distances change from 1.966(4) to 2.004(3) A, which is in agreement with those found in the previously published literatures [20-22]. All of the Cu-O bond lengths are in the normal range, except for Cu(1)-O(1) 2.310(2) A and Cu(2)-O(3)#1 2.342(2) A (symmetry codes: #1 x - 1, y, z), which may rise from the Jahn-Teller effect [22].

In complex I, PDA ions display trans-configuration and adopt two kinds of coordination modes which play different roles in the formation of the coordination polymers. The first type is that two oxygen atoms of one carboxyl group chelating coordinate with one metal ion, but one oxygen atom of the two coordinates with another metal ion too; in the other carboxyl group, one oxygen atom coordinates with two metal ions, but the other oxygen atom is free. The other type is each PDA anion acts as a bridge and coordinates to Cu2+ ions with all four oxygen atoms. As shown in Fig. 2, the PDA anions adopting the a coordination mode connect Cu2+ ions into one-dimensional chains, and the PDA anions adopting the coordination mode connect two chains together forming a one-dimensional infinite ladder-like chain.

In the crystal lattice of complex I, five crystallo-graphically independent water molecules O(7), O(8),

O(9), O(10) and O(11) and a free NO- anion are observed. There are abundant hydrogen bonds between them; the details of hydrogen bonds are listed in Table3. As shown in Fig. 3, we can see that O(8), O(10), O(8a), and O(10a) form a tetramer water cluster, at the same time, O(8), O(8a), O(10), O(10a), O(11), O(11a), O(12A), O(12Aa), O(14A), and O(14Aa) form a 10-membered hydrogen bonds ring. The tetramer water clusters and the 10-membered hydrogen bonds rings connect with each other alternately forming a one-dimensional hydrogen-bonding

KOOP,3HHAUHOHHAH XHMH3 tom 39 № 6 2013

Table 1. Crystallographic data and experimental details for complexes I and II

Parameter Value

I II

Color/shape Blue/block Green/block

Formula weight 1759.57 592.65

Crystal system, space group Tri

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