КООРДИНАЦИОННАЯ ХИМИЯ, 2014, том 40, № 5, с. 315-320
УДК 541.49
A NOVEL LANTHANIDE-ORGANIC WAVE-LIKE NETWORK WITH 1H-IMIDAZOLE-4,5-DICARBOXYLATE AND OXALATE: STRUCTURE, PHOTOLUMINESCENCE, AND MAGNETIC PROPERTIES
© 2014 L. Liu1, 2, J. Liu1, X. Feng2, *, S. Yang2, and L. Y. Wang 2, 3, *
1College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, 450001 P.R. China 2College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang, 471022 P.R. China 3College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang, 473601 P.R. China
*E-mail: wlya@lynu.edu.cn; fengx@lynu.edu.cn Received August 4, 2013
The solvothermal reaction of lanthanide nitrate and H4Diida ligand (H4Diida = 2-(4,5-dicarboxy-1H-imida-zol-2-yl)-1H-imidazole-4,5-dicarboxylic acid) in the presence of ammonium oxalate results in a new three-dimensional (3D) lanthanide-organic framework, namely, {[Pr(Ida)(p.2-C2O4)a5(H2O)2] ■ H2O}n (H2Ida = 1H-imidazole-4,5-dicarboxylic acid). H4Diida ligand can be in situ into Ida2- ions under the conditions, as unequivocally proved by these similar situations occurred in other systems. Single crystal X-ray diffraction analysis reveals the formation of a novel wave-like structure. It crystallizes in the monoclinic system, space group of P2i/c. The polymer is built from two kinds of parallel alternately 1D infinite chain through the carboxylate double-linking adjacent Pr3+ cations, forming an extended 2D bilayer-like structure along the yz plane. Moreover, the polymer further stacks via weak interactions to generate a 3D supramolecular framework. The photoluminescence and magnetic properties for the polymer were also investigated and discussed.
DOI: 10.7868/S0132344X14040057
INTRODUCTION
Nowadays, as an important branch in the field of crystal engineering, the reasonable design and preparation of lanthanide-organic frameworks (LnOFs) have become an attractive research field, mainly owing to their compositional and structural diversities, as well as potential applications in catalysis, ion exchange, magnetism, intercalation chemistry, photochemistry and materials chemistry [1—4]. Meanwhile, the imidazole and its derivatives are widely employed as functional ligands in coordination chemistry. The imidazole ring tends to adopt bidentate/bridging/tri-dentate for imidazolate anions to construct polynucle-ar or extending structures [5, 6]. In this paper, H4Diida (H4Diida = 2-(4,5-dicarboxy-1H-imidazol-2-yl)-1H-imidazole-4,5-dicarboxylic acid), a multifunctional ligand which has six sites for potential coordination to a metal center which contribute to increase the dimensionality of the assembled networks, has attracted much interest [7, 8]. Intriguingly, a new lanthanide-organic polymer {[Pr(Ida)(^2-C2O4)o.5(H2O)2] ■ H2O},, (I) (H2Ida = 1H-imidazole-4,5-dicarboxylic acid) was obtained by the solvothermal reaction of lanthanide nitrate, ammonium oxalate and H4Diida ligand. With no Ida2- ligand directly introduced to the starting materials, we supposed that Ida2- ligand might be derived from the decomposition of H4Diida, similar situations
also occurred in other systems [9, 10]. The synthesis, crystal structure, and thermal stability as well as the solid-state luminescence property of the polymer I are reported herein.
EXPERIMENTAL
Materials and physical measurements. All reagents used in the syntheses were of analytical grade and used as received. The infrared spectra (4000—400 cm-1) were recorded by using KBr pellet on an Avatar™ 360 ESP IR spectrometer. Thermogravimetry-differential thermal analysis was recorded using a SDT 2960 simultaneous thermal analyzer (DTA Instruments, New Castle, DE) in N2 atmosphere at a heating rate of 10°C min-1 from 30 to 900°C. Solid luminescence spectrum of the polymer was run on a Cary Eclipse fluorescence spectrophotometer. Variable-temperature magnetic susceptibilities were measured using a MPMS-7 SQUID magnetometer under a 0.2 T applied magnetic field and over the range of 2 to 300 K. Diamagnetic corrections were made with Pascal's constants for all constituent atoms.
Synthesis of {[Pr(Ma)(^-C2O4)0.5(H2O)2] • H2O},
2-(4,5-Dicarboxy-1H-imidazol-2-yl)-1H-imidazole-4,5-dicarboxylic acid (0.032 g, 0.1 mmol) and ammonium oxalate (0.015 g, 0.1 mmol) in a solution of wa-
316
LIU et al.
Table 1. Crystallographic data and experimental details for polymer I
Parameter Value
Empirical formula C6H7N2O9Pr
Formula weight 392.05
Temperature 293(2)
Crystal system Monoclinic
Space group Phjc
a, A 7.5071(15)
b, A 17.255(4)
c, A 8.5855(17)
P, deg 110.927(2)
V, A3 1038.8(4)
Z 4
p, g cm-3 2.507
F(000) 752.0
Crystal size, mm3 0.22 x 0.19 x 0.17
29 Range for data collection, deg 4.72-56.56
Limiting indice rangs -9 < h < 10
-9 < k < 23
-11 < l < 11
Reflections collected/unique 5533/2037
Rint 0.0610
Reflections with (I > 2ct(I)) 1979
Max. and min. transmissions 0.4997, 0.4221
Data/restraints/parameters 2508/0/168
GOOF 1.119
R1, wR2 (I > 2ct(I)) 0.0249, 0.0626
R1, wR2 (all data) 0.0260, 0.0632
Largest diff. peak and hole, e/A3 0.807 and -1.168
Ri = E F - iFci^lFoil, wR2 = Zww [Fo - Fc2|2/EW(Fw I2) 2]1/2.
ter-alcohol (v : v = 1.2, 10 mL) were mixed with an aqueous solution (10 mL) of Pr(NO3)3 • 6H2O (0.043 g, 0.1 mmol). After stirring for 20 min in air, the pH value was adjusted to 3.5 with nitric acid, and the mixture was placed into 25 mL Teflon-lined autoclave under autogenous pressure being heated at 155° C for 72 h, then the autoclave was cooled over a period of 24 h at a rate 5°C/h. After filtration, the product was washed with distilled water and then dried, yellow crystal of polymer I was obtained suitable for X-ray diffraction analysis.
X-ray crystallography. Single-crystal diffraction data of polymer I was collected on a Bruker SMART APEX CCD diffractometer with graphite-monochro-mated Mo^a radiation (X = 0.71073 A) at room temperature. The structure was solved using direct methods and successive Fourier difference synthesis (SHELXS-97) [11] and refined using the full-matrix
least-squares method on F2 with anisotropic thermal parameters for all nonhydrogen atoms (SHELXL-97) [12]. The disordered ethyl carbon atoms of Ida2-ligand were restrained in order to obtain reasonable thermal parameters. The hydrogen atoms of organic ligands were placed in calculated positions and refined using a riding on attached atoms with isotropic thermal parameters 1.2 times those of their carrier atoms. The summary crystallographic data for polymer I are given in Table 1, selected bond lengths and angles are listed in Table 2.
Crystallographic data for the structure I have been deposited with the Cambridge Crystallographic Data Centre (no. 940831; http://www.ccdc.cam.ac.uk/ conts/retrieving.html).
RESULTS AND DISCUSSION
Single crystal X-ray diffraction analysis reveals that polymer I crystallizes in the monoclinic system with space group of P21/c. As illustrated in Fig. 1, the asymmetric unit of I contains one lanthanide center Pr(1), one N(1) atom belonging to Ida2- ligand and eight O-atoms, among which two O(1), O(2) atoms are from oxalate ligand, four O(3), O(4), O(5), O(6) atoms are from carboxylate of three symmetry-related Ida2- ligands and two O(7), O(8) atoms are coordination water oxygen atoms. This leads to a nine-coordination sphere, which resembles a highly distorted tri-capped trigonal geometry with Pr-O bond lengths ranging from 2.425(3) to 2.632(2) A, and the Pr-N bond distance being 2.608(3) A. Additionally, the distortion of lanthanide coordination sphere is clearly reflected by the internal (N,O)-Pr-O bond angles: while the OPrO angles range between 63.79(8)° and 141.45(10)°, and the NPrO angles have been found to be in the range of 62.62(8)° to 142.45(9)°.
The coordination environment of Ida2- (a) and oxalate (b) in polymer I is illustrated below:
Pri :: Pri
(b) Scheme.
The oxalate ion is structurally located at a symmetry plane and bridges two symmetry-related lanthanide cations via a bis-bidentate chelate interaction, act as a tetradentate ligand [13]. These O,O-chelate interactions are crystallographic equivalent with a chelating angle of 63.79(8)° and originate an interme-tallic Pr(1)-Pr(1) distance of 6.5427(8) A. The Ida2-anionic ligand connects three crystallographically equivalent Pr(III) centers via three distinct coordina-
KOOP^HH^HOHHAtf XHMHfl TOM 40 № 5 2014
A NOVEL LANTHANIDE-ORGANIC WAVE-LIKE NETWORK 317
Table 2. Selected bond lengths (A) and bond angles (deg) for polymer I*
Bond d, A Bond d, A Bond d, A
Pr(1)—O(1)#1 2.534(2) Pr(1)-O(3) 2.425(3) Pr(1)-O(2) 2.540(2)
Pr(1)—O(4)#2 2.632(2) Pr(1)-O(7) 2.565(3) Pr(1)-O(5) 2.452(2)
Pr(1)—O(6)#3 2.537(2) Pr(1)—O(8) 2.496(3) Pr(1)—N(1)#3 2.608(3)
Angle ю, deg Angle ю, deg Angle ю, deg
O(1)#!pr(1)O(2) 63.79(8) O(3)Pr(1)N(1)#3 75.04(9) O(5)Pr(1)N(1)#3 75.92(9)
O(1)#!pr(1)O(4)#2 70.75(8) O(2)Pr(1)O(4)#2 70.95(8) O(6)#3Pr(1)O(2) 67.12(8)
O(1)#xPr(1)O(7) 124.82(8) O(2)Pr(1)O(7) 132.89(8) O(6)#3Pr(1)O(4)#2 129.59(7)
O(1)#!pr(1)O(6)#3 111.94(8) O(2)Pr(1)N(1)#3 88.60(9) O(6)#3Pr(1)O(7) 122.93(8)
O(1)#xPr(1)N(1)#3 72.00(9) O(7)Pr(1)O(4)#2 70.64(8) O(6)#3Pr(1)N(1)#3 62.62(8)
O(3)Pr(1)O(1)#! 73.38(9) O(7)Pr(1)N(1)#3 138.28(9) O(8)Pr(1)O(1)#! 134.61(9)
O(3)Pr(1)O(2) 137.06(8) O(5)Pr(1)O(1)#! 139.92(8) O(8)Pr(1)O(2) 77.61(8)
O(3)Pr(1)O(4)#2 98.49(8) O(5)Pr(1)O(2) 138.88(8) O(8)Pr(1)O(4)#2 74.89(8)
O(3)Pr(1)O(7) 75.05(9) O(5)Pr(1)O(4)#2 139.31(8) O(8)Pr(1)O(7) 66.87(9)
O(3)Pr(1)O(5) 75.65(8) O(5)Pr(1)O(7) 68.96(9) O(8)Pr(1)O(6)#3 69.96(8)
O(3)Pr(1)O(6)#3 131.36(8) O(5)Pr(1)O(6)#3 71.95(8) O(8)Pr(1)N(1)#3 132.28(8)
O(3)Pr(1)O(8) 141.45(10) O(5)Pr(1)O(8) 85.13(8) N(1)#3Pr(1)O(4)#2 142.45(9)
* Symmetry codes: #1 -x, 1 - y, 2 - z; #2 -x, 1 - y, 1 - z; #3 x, 3/2 - y, 1/2 + z; #4 x, 3/2 - y, -1/2 + z.
tion modes (see scheme), ultimately occurring in the crystal structure as a pentadentate ligand. On the one hand, the heteroatoms of the
Для дальнейшего прочтения статьи необходимо приобрести полный текст. Статьи высылаются в формате PDF на указанную при оплате почту. Время доставки составляет менее 10 минут. Стоимость одной статьи — 150 рублей.