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Metal-Organic Framework-Based Humidity Sensors
Published in Ghenadii Korotcenkov, Handbook of Humidity Measurement, 2020
Depending on the metal ion and its oxidation state, coordination numbers could commonly be 2–6 for transition metals, or 6–12 for lanthanides. Different coordination numbers result in various geometries, which can be linear, T- or Y-shaped, tetrahedral, square-planar, square-pyramidal, trigonal-bipyramidal, octahedral, trigonalprismatic, pentagonal-bipyramidal, or polyhedral coordination geometry, and the corresponding distorted forms (Kitagawa et al. 2004). Besides crystallinity, one great advantage of MOFs is that, given a starting framework geometry, it is possible to build frameworks that have the same topology, but that differ by the presence of functional groups and by the size of the organic building blocks. This concept, called isoreticularity (Eddaoudi et al. 2002; Cavka et al. 2008; Garibay and Cohen 2010), allows one to tune the pore size of the material and adds the possibility of introducing functional groups within the framework. Moreover, if two or more isoreticular organic linkers are employed, frameworks bearing different functionalities that are randomly and homogeneously distributed within the framework are produced by exploiting the concept of multi-variable or mixed MOFs (MTV-MOFs or MIXMOFs) (Burrows et al. 2008; Kleist et al. 2009; Deng et al. 2010).
Critical review on lanthanum-based materials used for water purification through adsorption of inorganic contaminants
Published in Critical Reviews in Environmental Science and Technology, 2022
Koh Yuen Koh, Yi Yang, J. Paul Chen
Metal–organic frameworks (MOFs) are a group of hybrid porous materials composed of metal-oxo clusters and organic building blocks (Farrusseng, 2011; Farrusseng et al., 2009; Gu et al., 2007; He et al., 2012; Huang, Wang, et al., 2014; Lin et al., 2010; Shah et al., 2012; Xiang et al., 2012). The texture and characteristics such as specific surface area, pore structure, and chemical stability are largely dependent upon the individual components. MOFs can separate molecules through physical sieving, chemical adsorption or chemical bonding and other mechanisms (Gu et al., 2007; Shah et al., 2012). MOFs work well in gas separation; however, the stability of many MOFs in water is still less satisfactory. Because of the large coordination sphere and flexible coordination geometry, La may be used to modify the MOFs in order to improve the hydro-stability. It can facilitate structural re-organization of the MOFs without destroying the overall framework structures (He et al., 2012; Xiang et al., 2012).
Five new cobalt(II) complexes based on indazole derivatives: synthesis, DNA binding and molecular docking study
Published in Journal of Coordination Chemistry, 2019
Bing-Fan Long, Qin Huang, Shu-Long Wang, Yan Mi, Meng-Fan Wang, Ting Xiong, Shu-Cong Zhang, Xian-Hong Yin, Fei-Long Hu
The structures of 1–5 were determined by X-ray diffraction. The summary of data collection, structure solution and refinement details are presented in Table 1. Single-crystal X-ray diffraction measurements reveal that 1 and 2 crystallize in space group P2(1)/c; the asymmetric unit contains one metal ion in the middle of the two symmetry indazole ligands. At the same time, the Co2+ ions in 1 and 2 are six-coordinate, adopting distorted octahedron coordination geometry. As shown in Figure 1, two indazole ligands and one N-donor ligand (phen or 5,5′-dimethyl-2,2′-bipy) coordinated to the central ions in the chelating fashion (Scheme 1, A), in which the indazole acid was coordinated to the metal ions through its carboxyl O atoms and pyrazole N atoms. Such coordination model was also observed in other pyrazole derivatives complexes [18]. In this way, two indazole ligands serve as two wings of a butterfly as can be seen in Figure 1. As might be imagined that stacking interaction between the phen ligands also plays an important role in the formation of the structure. Two adjacent phen ligands are connected by π-π stacking interactions with the distance of 3.588 Å between phen ligands in 1 (3.586 Å between the 5,5′-dimethyl-2,2′-bipy molecules in 2) (Supplementary Information Figure S4). This interaction is similar to compounds reported recently [19].
Structure, fluorescence, and carbon dioxide capture of a carboxylate cadmium complex
Published in Journal of Coordination Chemistry, 2018
Qiang Zhao, Chenghua Ding, Yuquan Feng
The result of X-ray diffraction analysis revealed that the complex, with a formula of Cd2C16H12O12, crystallizes in the triclinic system, space group P-1. The asymmetric unit consists of two Cd ions, one dcpa ligand and three water molecules (O3, O11, and O12) in the lattice. As depicted in Figure 1(a), Cd1 is surrounded by five O atoms (O1, O2, O5B, O7C, and O9C) from a dcpa ligand and one O atom (O3) from water; Cd2 is surrounded by five O atoms (O4A, O5A, O8D, O10, and O10E) from a dcpa ligand and one O atom (O11) from water. The coordination geometry can be described as a distorted octahedron. The O-Cd-O angles are in the range of 53.06(14) to 159.75(17)°. The Cd–O bond lengths are in the range of 2.244(4)–2.474(4) Å; the bond lengths are within the normal range. The neighboring Cd ions were linked by the carboxylate groups along the a-axis to form a rod-shaped secondary building unit (SBU) (Figure 1(b)). The adjacent SBUs were further linked by the dcpa ligand to form a three-dimensional network structure (Figure 1(c)).