Syntheses of Two New 1D and 3D Networks of Cu(II) and Co(II) Using Malonate and Urotropine as Bridging Ligands: Crystal Structures and Magnetic Studies
TL;DR: Two new metal-organic based polymeric complexes have been synthesized and characterized by X-ray crystal structure determination and magnetic studies and the fit of the magnetic data considering intralayer interaction through carboxylate pathway as well as interlayer interaction via urotropine pathway gave no satisfactory result.
Abstract: Two new metal-organic based polymeric complexes, [Cu(4)(O(2)CCH(2)CO(2))(4)(L)].7H(2)O (1) and [Co(2)(O(2)CCH(2)CO(2))(2)(L)].2H(2)O (2) [L = hexamethylenetetramine (urotropine)], have been synthesized and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 is a 1D coordination polymer comprising a carboxylato bridged Cu(4) moiety linked by a tetradentate bridging urotropine. Complex 2 is a 3D coordination polymer made of pseudo-two-dimensional layers of Co(II) ions linked by malonate anions in syn-anti conformation which are bridged by bidentate urotropine in trans fashion. Complex 1 crystallizes in the orthorhombic system, space group Pmmn, with a = 14.80(2) A, b = 14.54(2) A, c = 7.325(10) A, beta = 90 degrees, and Z = 4. Complex 2 crystallizes in the orthorhombic system, space group Imm2, a = 7.584(11) A, b = 15.80(2) A, c = 6.939(13) A, beta = 90.10 degrees (1), and Z = 4. Variable temperature (300-2 K) magnetic behavior reveals the existence of ferro- and antiferromagnetic interactions in 1 and only antiferromagnetic interactions in 2. The best fitted parameters for complex 1 are J = 13.5 cm(-)(1), J' = -18.1 cm(-)(1), and g = 2.14 considering only intra-Cu(4) interactions through carboxylate and urotropine pathways. In case of complex 2, the fit of the magnetic data considering intralayer interaction through carboxylate pathway as well as interlayer interaction via urotropine pathway gave no satisfactory result at this moment using any model known due to considerable orbital contribution of Co(II) ions to the magnetic moment and its complicated structure. Assuming isolated Co(II) ions (without any coupling, J = 0) the shape of the chi(M)T curve fits well with experimental data except at very low temperatures.
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TL;DR: This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications.
Abstract: The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)
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TL;DR: A synthetic and structural comparison of Co(II)-cluster-based coordination polymers demonstrates that the features of auxiliary N-donor ligands play a key role in governing the in situ formed clusters and the final 3-D coordination frameworks.
Abstract: Two novel Co(II)-cluster-based coordination polymers—namely, [Co5(μ3–OH)2(1,4-ndc)4(bix)2]n (1) and {[Co8(μ3–OH)4(1,4-ndc)6(btp)(H2O)6]·H2O}n (2)—were prepared by hydrothermal reactions of Co(II) perchlorate with 1,4-naphthalenedicarboxylic acid (1,4-H2ndc) and different N-donor coligands (bix = 1,4-bis(imidazol-1-ylmethyl)benzene and btp = 4,4′-bis(triazol-1-ylmethyl)biphenyl). In 1, 10-connected [Co5(μ3–OH)2(COO)8] clusters are extended by the μ4-1,4-ndc2– and trans-bix ligands to construct a rare, self-penetrating ile framework that can interestingly be regarded as the cross-link of two interpenetrating 6-connected pcu networks. While for 2, [Co8(μ3–OH)4(COO)12] clusters serve as the 8-connected nodes, which are bridged by the μ4/μ5-1,4-ndc2- and trans-btp ligands to afford the highest-connected uninodal self-penetrating (420.68) network based on octacobalt clusters. A synthetic and structural comparison of 1 and 2 demonstrates that the features of auxiliary N-donor ligands play a key role in governing...
221 citations
TL;DR: Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric, trimeric, and tetrameric motifs to polymeric chains depending upon the coligands used.
Abstract: Five new MnII coordination polymers, namely [Mn2(tbip)2(bix)] (1), [Mn3(tbip)3(bix)2] (2), [Mn3(tbip)2(Htbip)2(bib)2]·4H2O (3), [Mn4(tbip)4(bbp)2(H2O)2] (4), and [Mn4(tbip)4(bip)]·2H2O (5), were prepared by hydrothermal reactions of Mn(II) acetate with H2tbip (5-tert-butyl isophthalic acid) in the presence of different di-imidazolyl coligands (bix =1,4-bis(imidazol-1-ylmethyl)benzene, bib =1,4-bis(imidazol) butane, bbp =1,3-bis(benzimidazol)propane, bip =1,3-bis(imidazol)propane). All complexes were characterized by elemental analysis, IR spectra, thermogravimetric analysis, single-crystal X-ray crystallography, and powder X-ray diffraction. Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric, trimeric, and tetrameric motifs to polymeric chains depending upon the coligands used. Complex 1 has a 3D 6-connected polycatenane network with dinuclear [Mn2O2] secondary building units. Complex 2 possesses a 3D 8-connected structure with trinuclear ...
184 citations
TL;DR: Five novel lanthanide complexes with the formulas H3bta = 1,3,5-benzenetriacetic acid, in which the bta3- ligands adopt different coordination modes, showed strong luminescence upon excitation, and their luminescent decay curves fit well with single exponential decays.
Abstract: Five novel lanthanide complexes with the formulas [Nd(bta)(H2O)2.4.35H2O]n(1), [Sm(bta)(H2O)2.4.5H2O]n (2), [Eu(bta)(H2O).1.48H2O]n (3), [Tb(bta)(H2O).1.31H2O]n (4), and [Yb(bta)(H2O).H2O]n (5) (H3bta = 1,3,5-benzenetriacetic acid) have been prepared by using the corresponding lanthanide salt and H3bta. The results of an X-ray crystallographic analysis revealed that all the complexes have three-dimensional channel-like structures, in which the bta3- ligands adopt different coordination modes: monodentate and mu2-eta2:eta1-bridging coordination modes in 1, 2, and 5 and mu2-eta1:eta1-bridging and mu2-eta2:eta1-bridging coordination modes in 3 and 4, respectively. Complexes 1 and 2, as well as 3 and 4, are isostructural, respectively, in which all the Ln(III) (Ln = Nd, Sm, Eu, and Tb) atoms are nine-coordinated, while the Yb(III) atoms in complex 5 are eight-coordinated. Both complexes 3 and 4 showed strong luminescence upon excitation, and their luminescence decay curves fit well with single exponential decays of which the lifetime is 0.45 ms for 3 and 1.0 ms for 4. The magnetic properties of the complexes were investigated in the temperature range of 1.8-300 K.
171 citations
TL;DR: In this paper, five different dicarboxylic acids, namely, fumaric dioic acid (H2FUM), 2-aminoterephthalmic acid (2-H2ATA), 1,4-naphthalenedic-arboxylate anions (1,2-BDC), oxalic acid, and 2-amino-phthalic acid were employed as the secondary auxiliary ligands to perform a systematic study on the structure diversities in the Zn(II)-1.4-bis(imid
Abstract: In the field of metal–organic frameworks (MOFs), one of the challenges is the fabrication of novel materials that display/correlate the prediction of structures and functionality. Usually, the structures of MOFs are influenced by the skeleton of ligands. In this article, five different dicarboxylic acids, namely, fumaric dioic acid (H2FUM), 2-aminoterephthalic acid (2-H2ATA), 1,4-naphthalenedicarboxylic acid (1,4-H2NAPDC), 1,2-benzenedicarboxylic acid (1,2-H2BDC), and oxalic acid (H2OX) are employed as the secondary auxiliary ligands to perform a systematic study on the structure diversities in the Zn(II)–1,4-bis(imidazol-1-yl)benzene (L) frameworks. By introducing various secondary dicarboxylate anions in the Zn(II)-L system, six new complexes {Zn(L)(FUM)}∞ (1), {Zn2(L)(2-ATA)2}∞ (2), {Zn(L)(1,4-NAPDC)·H2O}∞ (3), {Zn2(L)(1,4-NAPDC)2·2DMF}∞ (4), {Zn(L)(1,2-BDC)}∞ (5), and {Zn3(L)2(OX)3·H2O}∞ (6) were obtained. Complexes 1 and 3 possess three-dimensional (3D) 5-fold interpenetrating diamond frameworks. Com...
164 citations
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TL;DR: In this article, a phase annealing method, related to the simulated-annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution.
Abstract: A number of extensions to the multisolution approach to the crystallographic phase problem are discussed in which the negative quartet relations play an important role. A phase annealing method, related to the simulated annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution. The ideas presented here are incorporated in the program system SHELX-90; the philosophical and mathematical background to the direct-methods part (SHELXS) of this system is described.
14,787 citations
TL;DR: In this paper, a highly porous metal coordination polymer [Cu3(TMA)2(H2O)3]n (where TMA is benzene-1,3,5-tricarboxylate) was formed in 80 percent yield.
Abstract: Although zeolites and related materials combine nanoporosity with high thermal stability, they are difficult to modify or derivatize in a systematic way. A highly porous metal coordination polymer [Cu3(TMA)2(H2O)3]n (where TMA is benzene-1,3,5-tricarboxylate) was formed in 80 percent yield. It has interconnected [Cu2(O2CR)4] units (where R is an aromatic ring), which create a three-dimensional system of channels with a pore size of 1 nanometer and an accessible porosity of about 40 percent in the solid. Unlike zeolites, the channel linings can be chemically functionalized; for example, the aqua ligands can be replaced by pyridines. Thermal gravimetric analysis and high-temperature single-crystal diffractometry indicate that the framework is stable up to 240 degreesC.
5,061 citations
TL;DR: In this article, a Fourier series in the polar angles of the incident and diffracted beam paths is used to model an absorption surface for the difference between the observed and calculated structure factors.
Abstract: Absorption effects usually present the most serious source of systematic error in the determination of structure factors from single-crystal X-ray diffraction measurements if the crystal is not ground to a sphere or cylinder. A novel method is proposed for the correction of these effects for data collected on a diffractometer. The method works from the premise that the manifestation of systematic errors due to absorption, unlike most other sources of systematic error, will not be evenly distributed through reciprocal space, but will be localized. A Fourier series in the polar angles of the incident and diffracted beam paths is used to model an absorption surface for the difference between the observed and calculated structure factors. Knowledge of crystal dimensions or linear absorption coefficient is not required, and the method does not necessitate the measurement of azimuthal scans or any extra data beyond the unique set. Moreover, application of the correction is not dependent upon the Laue symmetry of the crystal or the geometry of the diffractometer. The method is compared with other commonly used corrections and results are presented which demonstrate its potential.
4,930 citations
TL;DR: Consideration of the geometric and chemical attributes of the SBUs and linkers leads to prediction of the framework topology, and in turn to the design and synthesis of a new class of porous materials with robust structures and high porosity.
Abstract: Secondary building units (SBUs) are molecular complexes and cluster entities in which ligand coordination modes and metal coordination environments can be utilized in the transformation of these fragments into extended porous networks using polytopic linkers (1,4-benzenedicarboxylate, 1,3,5,7-adamantanetetracarboxylate, etc.). Consideration of the geometric and chemical attributes of the SBUs and linkers leads to prediction of the framework topology, and in turn to the design and synthesis of a new class of porous materials with robust structures and high porosity.
4,753 citations