Abstract
Here we show the important role played by the size of the lanthanoid and the solvent used in the final structures of several two-dimensional magnetic coordination polymers with the ligand chlorocyananilato, (C6O4(CN)Cl)2−. With this aim we have prepared five compounds: [Nd2(C6O4(CN)Cl)3(DMF)6] (1) (DMF = dimethylformamide), [Dy2(C6O4(CN)Cl)3(DMF)6]·4H2O (2), [Ho2(C6O4(CN)Cl)3(DMF)6]·2H2O (3), and [Ln2(C6O4(CN)Cl)3(DMSO)6] with Ln = Ce (4) and Nd (5) (DMSO = dimethylsulfoxide). These compounds are formed by two dimensional networks with a (6,3)-topology but, depending on the size of the lanthanoid and on the solvent used, show important structural differences, including the size, shape, distortion and content of the cavities as well as the flatness of the layers. The comparison of compounds 1–3 and 4–5 shows the role played by the size of the lanthanoid while keeping constant the solvent, whereas, the comparison of compounds 1 and 5 shows the role of the solvent (DMF vs. DMSO) while keeping constant the lanthanoid. The magnetic properties of all of them show the absence of noticeable magnetic interactions, in agreement with previous results that can be explained by the internal character of the 4f electron and the weak magnetic coupling mediated by these anilato-based ligands.
Highlights
The synthesis of porous crystalline coordination polymers known as metal organic frameworks (MOFs) presenting different cavities shapes and sizes is a hot topic in Coordination Chemistry nowadays [1,2]
The possibility to tune and modulate the shape and size of the cavities is a very important aspect in order to synthetize MOFs with tailored properties for applications in catalysis [3,4], gas storage and separation [5,6], energy storage [7,8], water adsorption [9], biomedicine [10,11], sensors [12,13], or a combination of several properties in the same MOF [14]. These MOFs are mainly constructed with transition metal atoms and complexes of these metal ions that are connected through different organic ligands acting as linkers
We extend this study with the asymmetric chlorocyananilato ligand and dimethylformamide (DMF) and dimethylsulfoxide (DMSO) as solvents with four more Ln(III) ions (Ce, Nd, Dy and Ho) to prepare five new compounds formulated as: [Nd2(C6O4(CN)Cl)3(DMF)6] (1) [Dy2(C6O4 (CN)Cl)3(DMF)6]·4H2O (2), [Ho2(C6O4(CN)Cl)3(DMF)6]·2H2O (3), and [Ln2(C6O4(CN)Cl)3(DMSO)6] with Ln = Ce (4) and Nd (5). These five compounds, together with the four compounds previously reported with the same ligand and identical stoichiometry: [Ce2(C6O4(CN)Cl)3(DMF)6]·2H2O (I), [Pr2(C6O4(CN)Cl)3(DMF)6] (II), [Pr2(C6O4(CN)Cl)3(DMSO)6] (III) and [Yb2(C6O4(CN)Cl)3 (DMSO)4]·2H2O (IV) [39] will allow us to obtain a deeper knowledge of the role played by both factors: the size of the Ln(III) ion and the solvent (DMF and DMSO) with the asymmetric ligand chlorocyananilato
Summary
The synthesis of porous crystalline coordination polymers known as metal organic frameworks (MOFs) presenting different cavities shapes and sizes is a hot topic in Coordination Chemistry nowadays [1,2]. A larger study of the role of the solvent performed with the chloranilato ligand and Er(III) in the series of compounds [Er2(C6O4Cl2)3(H2O)6]·10H2O, [Er2(C6O4Cl2)3(DMF)6], [Er2(C6O4Cl2)3(DMA)4]·5H2O (DMA = dimethylacetamide), [Er2(C6O4Cl2)3(DMSO)4]·2DMSO·2H2O, [Er2(C6O4Cl2)3(FMA)6]·4FMA·2H2O (FMA = formamide) and [Er2(C6O4Cl2)3(HMPA)(H2O)3]·H2O (HMPA = hexamethylphosphormamide) showed that the size and steric hindrance of the solvent determines the coordination number and geometry, the size and shape of the cavities and, the presence of solvent and water molecules in the cavities [42] All these results indicate that the solvent plays a very important role in the final structure. These five compounds, together with the four compounds previously reported with the same ligand and identical stoichiometry: [Ce2(C6O4(CN)Cl)3(DMF)6]·2H2O (I), [Pr2(C6O4(CN)Cl)3(DMF)6] (II), [Pr2(C6O4(CN)Cl)3(DMSO)6] (III) and [Yb2(C6O4(CN)Cl) (DMSO)4]·2H2O (IV) [39] will allow us to obtain a deeper knowledge of the role played by both factors: the size of the Ln(III) ion and the solvent (DMF and DMSO) with the asymmetric ligand chlorocyananilato
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