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Merits of Selecting Metal-Organic Frameworks as Sensors
Published in Ram K. Gupta, Tahir Rasheed, Tuan Anh Nguyen, Muhammad Bilal, Metal-Organic Frameworks-Based Hybrid Materials for Environmental Sensing and Monitoring, 2022
Harmeet Kaur, Amit L Sharma, Akash Deep
MOFs are formed through reticular coordination bonding of metal clusters and organic bridging ligands. Mostly, the metal clusters are formed in-situ while the linkers are pre-formed. The structure of the MOF is dependent upon the connectivity and geometry of the linker. The size, shape, or other properties of a MOF for an intended application can be tuned by tailoring the length, geometry, or functional groups on the ligand. The common tuning methods include solvent-assisted linker exchange, trans-metalation for MOF functionalization, and non-bridging ligand replacement. The solvent-assisted linker exchange focuses on substitution reactions for desired metal-ligand bond formations. Diverse classes of linker geometries including heterocyclic, ditopic, tritopic, hexatropic, octatopic, desymmetrized, and so on, have been explored for synthesizing MOFs and to tune their structure and functionality. Stimuli-responsive MOFs have been reported through the use of flexible linkers. Post synthetic modification enables the introduction of guest moieties with desired attributes. Desired functional groups are generally attached to the linkers upon post-modification. Recently, template-directed synthesis of MOFs has also been introduced wherein the MOFs act as hosts to template the chemical reactions between the guest species [10, 11].
Porous Inorganic Nanoarchitectures for Catalysts
Published in Qingmin Ji, Harald Fuchs, Soft Matters for Catalysts, 2019
Qingmin Ji, Jiao Sun, Shenmin Zhu
Abe et al. reported the formation of silica supported Pt catalysis system by directly mixing dendrimers-covered Pt nanoparticles into a compartment-rich porous silica capsules [47]. The surface dendrimers (hydroxyl-terminated generation 6 polyamidoamine dendrimers) favor the encapsulation of Pt nanoparticles in the porous capsules. In contrast to channel-type mesoporous supports or solid supports, the compartment-rich silica capsules showed an enhanced loading capacity and confinement effect to prevent the sintering of Pt nanoparticle under high temperature (Fig. 6.6). The system showed superior catalytic activity in high-temperature CO oxidation. Budroni et al. prepared porous supported Pd catalysts by capped 1-dodecanethiol and 3-mercaptopropyltrimethoxysilane with Pd nanoparticles. The following co-condensation of silicate precursors with modified Pd nanoparticles resulted into a homogeneous incorporation of Pd nanoparticles into a sponge-like porous silica [48]. Both the pore and catalysis components can be controlled by the bridging ligand, the initial size and the necessary catalytic functionality of nanoparticles can be maintained into the porous network. The coassembly of the bifunctional components (template and catalyst) into the porous nanoarchitecture differs from the routes by post-impregnation of catalytic nanoparticles. This strategy allows more precise manipulation on the size of catalytic nanoparticles, pore structures of the supports, and the loading amount of catalytic nanoparticles within the porous support.
Ruthenium Aryl Sulfides Complexes
Published in Ajay Kumar Mishra, Lallan Mishra, Ruthenium Chemistry, 2018
Minu Gupta Bhowon, Sabina Jhaumeer Laulloo
The binol-based diphosphate ligand (PSP) is not capable of chelating a transition metal since the p-thiophenol spacer is too large. However, it readily bridges two ruthenium centers to give the dinuclear complex [Ru2Cl4(L)2(PSP)] (L = C6H6, C6H4(CH3)(iPr), (Fig. 9.24) upon the reaction of the dimeric complex [(η6-C6H6)RuCl2]2 with PSP in CH2Cl2/benzene. In this complex PSP act as a bidentate bridging ligand bonded to two ruthenium atoms via phosphorous atoms (Chen et al., 2002).
Ferrimagnetic behavior in a naphthalene templated manganese(II) 1,1-cyclohexanediacetate compound
Published in Journal of Coordination Chemistry, 2022
Oscar Fabelo, Laura Cañadillas-Delgado, Jorge Pasán
Multidimensional molecular-based magnets have been the subject of considerable research over the past decades, both from a fundamental and device point of view [1–6]. Specifically, 3D coordination polymers with large cavity structures are of interest in the field of molecular magnetism and material-chemistry due to their fascinating structural diversities and their potential application as functional materials [7]. A commonly used strategy in the construction of such extended architectures is to employ appropriate bridging ligands that act as connectors between different metal centers. The role of the bridging ligand is twofold, stabilizing the 3D crystal structure and transmitting the magnetic interaction between the magnetic metal centers. In order to build materials with larger cavities, the bridging ligands must connect the metal centers further apart. For this reason, although a large number of these new materials, commonly known as MOFs (metal organic frameworks), with large cavities have been reported in recent years, the number of magnetic MOFs remains small [8–10]. Together with this strategy, the addition of a template, involving a self-assembly process through weak interactions, promotes the synthesis and crystallization of new coordination polymers [11]. The investigation of templated polymerizations is essential to develop a deeper understanding of the binding interaction between the host coordination polymer and guest template molecules [12,13].
Novel heterometallic Zn(II)-L-Cu(II) complexes: studies of the nucleophilic substitution reactions, antimicrobial, redox and cytotoxic activity
Published in Journal of Coordination Chemistry, 2022
Asija Halilagić, Enisa Selimović, Jelena S. Katanić Stanković, Nikola Srećković, Katarina Virijević, Marko N. Živanović, Biljana Šmit, Tanja V. Soldatović
Different orders of reactivity for the substitution reactions between Zn-L1-Cu and Zn-L2-Cu complexes and biological relevant nucleophiles were obtained. The established order of reactivity for the first reaction was GSH > 5′-IMP > 5′-GMP for Zn-L1-Cu, while 5′-GMP > GSH > 5′-IMP for Zn-L2-Cu. The obtained results indicate that the type of bridging ligand is very important, as well as the presence of inert ligand. Terpyridine as inert tridentate ligand induced strong electronic interaction between inert system and metal ion. The formation of π-back bonding of the in-plane pyridine moieties with the non-bonding d electrons increased the electrophilicity of the metal center and reactivity during substitution process. The π-acceptor ability of the pyrazine ligand decreased an electron density on the centers, by which the metal centers become more electrophilic and favor the rapid binding of the entering nucleophile. Long distance between the zinc(II) and copper(II) lead to less reactivity of both centers because of reduced electronic communication between them and an increasing of electron density on the metal centers.