КООРДИНАЦИОННАЯ ХИМИЯ, 2007, том 33, № 7, с. 483-492
УДК 541.49
Functional Self-Assembly of Hydrogen-Bonded 3D Coordination Networks Constructed from 1,2,4,5-Benzenetetracarboxylic Acid
© 2007 Q. B. Bo, S. Y. Zhao, Z. W. Zhang, Y. L. Sheng, Z. X. Sun, G. X. Sun,
C. L. Chen, and Y. X. Li
Institute of Chemistry and Chemical Engineering, Jinan University, Jinan, Shandong, 250022 P. R. China
Received June 8, 2006
Hydrothermal synthesis, characterization (IR, TG/DTA, element analysis, inductively coupled plasma (ICP)) and single-crystal X-ray structures of H4Btec hydrate and its two cobalt complexes, colorless [H4Btec • 2H2O]n (I), pink [Co(H2O)6(H2Btec)]„ (II), and nacarat {[Co(H2O)3(H2Btec)(Phen)] • H2O}n (III) (H4Btec = 1,2,4,5-benzenetetracar-boxylic acid, Phen = 1,10-phenanthroline) have been solved. The results showed that I forms a 3D O-H-O hydrogen-bonded network generated from H4Btec and water molecules, II presents a 3D network constructed by mononuclear [Co(H2O)6]2+ cations and H2Btec2- dianions through extensive hydrogen-bonding interactions, and III gives rise to a pseudo-octahedral coordination geometry. Extensive hydrogen-bonding interactions have significant effects in configuring a 3D network constructed by mononuclear [Co(H2Btec)(Phen)(H2O)3] neutral molecules and a water molecules.
INTRODUCTION
Considerable effort has recently been given to understanding a relationship between molecular and crystal structures, especially from the viewpoint of crystal engineering [1-3]. Therefore, the crystal engineering of su-pramolecular architectures or metal-organic coordination polymers has attracted much attention in the past decades [4-7]. The ultimate goal of crystal engineering is to design specific crystal structures with potential specific physical and chemical properties based only on the knowledge of the building blocks. As a result, a particular emphasis is placed on identifying reliable and robust intermolecular interactions, especially on the use of hydrogen bonds.
Hydrogen bonds have been recognized as being of fundamental importance in determining the supramolecu-lar structure of organic solids [8-9]. Its usage in crystal engineering is also found in many references [10-12].
Assemblies based on the carboxylic group (-COOH) are very well-known because of its ability to form robust hydrogen bonds on its own and also with several other compounds forming either O-H—N or O-H—N/C-H—O hydrogen bonds, as well as dative bonds through the car-boxylate group [13, 14].
H4Btec with four carboxylic acid groups symmetrically arranged around a benzene ring has been extensively studied. The interest in the inorganic-organic solids has been focused upon hydrogen-bonded networks that are sustained by partially deprotonated anionic forms of H^Btec. Therefore, H^Btec was often chosen as a building unit for the layers being a molecule with predictable and interesting supramolecular properties as a consequence of its molecular symmetry and complementary hydrogen-bonding capabilities.
It is known that the deprotonated forms of H4Btec can act not only as hydrogen-bond acceptors but also as hy-
drogen-bond donors, depending on the deprotonated car-boxyl groups, to give different supramolecular adducts. H^Btec is also an excellent bridging ligand, and a number of one-, two- and three-dimensional infinite metal frameworks have already been generated [15-22]. However, of the above-mentioned frameworks, are generated directly by coordination bonds. Indeed, very few organic structures containing H4PMA or its derivatives are known.
Here we report the preparation and crystal structures of three novel 3D organic-inorganic hybrid networks self-assembled by hydrogen-bonding interactions in which 2D coordination sheets formed by the self-assembly of organic molecules or hydrated metal-ion building blocks are generated first and further extended into 3D networks by hydrogen-bonding interactions. At the same time, their thermal stabilities and FT-IR modes are also discussed.
EXPERIMENTAL
Materials and apparatus. All starting materials were reagent grade, purchased commercially, and used without further purification.
Elemental analyses (C, H, and N) were carried out on a Perkin Elmer 2400 Series II CHNS/O elemental analyzer. Inductively coupled plasma (ICP) analysis (Co) was performed on a Perkin Elmer Optima 3300DV spectrometer. FT-IR spectra were measured on a Perkin Elmer FT-IR spectrometer in the 4000-200 cm-1 region with the pressed CsI pellets. The thermal stability of the compounds was examined by TG/DTA experiments, which were carried out under a flow of dry air and at a heating rate of 10 K min-1 with a Perkin Elmer Diamond TG/DTA instrument.
Synthesis of [H4Btec • 2H2O]„ (I). Compound was prepared hydrothermally from a mixture of CoCl2 • 6H2O, 1,2,4,5-benzentetracarboxylic dianhydride, and H2O in a
Table 1. Summary of crystallographic data and structure refinement for I-III
Compound I II III
Formula weight 290.18 419.16 563.33
Crystal system Triclinic Monoclinic Monoclinic
Space group P1 P2/m P21/n
a, A 5.4804(19) 6.513(5) 7.081(4)
b, A 6.475(2) 9.940(8) 22.533(12)
c, A 9.138(3) 6.549(5) 14.772(8)
a, deg 72.114(4) 90 90
P, deg 88.896(5) 115.388(8) 97.807(9)
Y, deg 73.436(5) 90 90
Volume, A3 294.97(17) 383.0(5) 2335(2)
Z 1 1 4
Pcalcd/g cm-3 1.634 1.817 1.602
mm-1 0.151 1.198 0.806
Reflections 1518 1884 11390
collected
Independent 1014 688 3955
reflections (R^ = 0.0220) (Rint = 0.0471) (Rint = 0.0912)
Final R indices R1 = 0.0563, R1 = 0.0657, R1 = 0.0878,
(I > 2o(/)) wR2 = 0.1338 wR2 = 0.1820 wR2 = 0.1915
R indices R1 = 0.0618, R1 = 0.0687, R1 = 0.154,
(all data) wR2 = 0.1433 wR2 = 0.1838 wR2 = 0.2258
molar ratio of 1 : 1 : 1200 by heating in a teflon-lined stainless steel autoclave at 140°C for 3 days under static conditions, and the filling volume is 75%. After cooling the reaction mixture to room temperature, only the colorless grain-like crystals appeared together with pink solutions. The crystals obtained were separated and multiply washed with distilled water and ethanol. Finally, the products were dried in air at room temperature. The yield was 40%.
For C10H10O10 anal. calcd, %: Found, %:
C, 41.39; C, 41.30;
H, 3.47. H, 3.54.
IR spectrum (v, cm1): 272 w, 278 w, 349 m, 401 w, 461 m, 510 w, 557 m, 651 m, 754 s, 816 s, 932 w, 959 m, 1077 w, 1118 s, 1250 vs, 1279 sh, 1306 vs, 1415 sh, 1445 m, 1511 s, 1612 m, 1674 vs, 1709 ssh, 1901 w, 2017 m, 2510 m, 2603 w, 2652 w, 2822 w, 2960 w, 3059 w, 3141 s, 3398 m, 3529 ssh.
Synthesis of [Co(H2O)6(H2Btec)]„ (II). Compound was prepared hydrothermally from a mixture of CoCl2 • • 6H2O, 1,2,4,5-benzentetracarboxylic dianhydride, ammonium molybdate (NH4)Mo7O24 • 6H2O, and H2O in a molar ratio of 1 : 2 : 1 : 900 by heating in a teflon-lined stainless steel autoclave at 160°C for 3 days under static conditions, and the filling volume is 75%. After cooling the
reaction mixture to room temperature, only the pink grainlike crystals appeared on the walls of the reaction container together with pink solutions and an amorphous substance. The crystals obtained were separated and washed with distilled water and ethanol many times. Finally, the products were dried in air at room temperature. The yield was 20%.
For C10H16CoO14
anal. calcd, %: C, 28.65; H, 3.85; Co, 14.06. Found, %: C, 28.73; H, 3.76; Co, 14.01.
IR spectrum (v, cm1): 245 w, 341 w, 425 m, 705 s, 745 s, 889 w, 1101m, 1157 vs, 1284 s, 1349 vs, 1586 s, 1666 s, 3457 vs.
Synthesis of {[Co(H2O)3(H2BtecXPhen)] • H2O}„ (III). Compound was prepared hydrothermally from a mixture of CoCl2 • 6H2O, 1,2,4,5-benzentetracarboxylic dianhydride, Phen, and H2O in a molar ratio of 1 : 2 : 1: 1340 by heating in a teflon-lined stainless steel autoclave at 200°C for 3 days under static conditions, and the filling volume is 75%. After cooling the reaction mixture to room temperature, the saffron prism-like crystals appeared on the bottom of the reaction container together with colorless solutions. The crystals obtained were separated and washed with distilled water and ethanol many times. Finally, the products were dried in air at room temperature. The yield was 80%.
For c22h2qcon2012
anal. calcd, %: C, 46.91; H, 3.58; N, 4.97; Co, 10.46. Found, %: C, 46.81; H, 3.65; N, 4.90; Co, 10.35.
IR spectrum (v, cm1): 425 m, 461 w, 481 w, 599 m, 644 w, 674 s, 730 vs, 755 s, 775 w, 848 vs, 869 m, 959 w, 1104 w, 1149 m, 1223 w, 1294 m, 1349 vs, 1426 s, 1516 w, 1582 w, 1692 s, 1819 w, 1994 w, 2367 w, 3459 s.
Crystal structure determination and refinement. A suitable single crystal with dimensions of 0.53 x 0.47 x x 0.45 mm for I, 0.50 x 0.48 x 0.41 mm for II and 0.25 x x 0.18 x 0.12 mm for III were carefully selected under an optical microscope and glued to a thin glass fiber with ep-oxy resin. X-ray intensity data were measured at 298(2) K on a Bruker SMART APEX CCD-based diffractometer (Mo^a radiation, X = 0.71073 A). The raw frame data for the compound were integrated into SHELX-format reflection files and corrected for Lorentz and polarization effects using SAINT [23]. Corrections for incident and diffracted beam absorption effects were applied using SADABS [23]. Compounds I, II, and III crystallized in the space group P1, P2/m, and P2x/n, respectively, as determined by systematic absences in the intensity data, intensity statistics, and the successful solution and refinement of the structures. All structures were solved by a combination of direct methods and difference Fourier syntheses and refined against F2 by the full-matrix least-squares technique. Crystal data, data collection parameters, and refinement statistics for compounds I-III are listed in Table 1. Selected bond distances and bond angles are given in Table 2. The
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Table 2. Selected bond distances (A) and angles (deg) for I-III
Bond d, A Bond d, A Bond d, A Angle ra, deg Angle ra, deg
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