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Polymer-Based Organic Electronics
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Tariq Altalhi, Polymers in Energy Conversion and Storage, 2022
Sonali Verma, Bhavya Padha, Prerna, Sandeep Arya
In the past two decades, macrocycles with rigid and fully π-conjugated backbones, because of their useful features and ability to serve as units for discotic liquid crystals, guest-host complexes, as well as for 3D nanomaterials, have become very popular. Furthermore, as discrete molecular entities, macrocycles exhibit some exceptional properties that are highly desirable in organic electronics [132]. These conjugated macrocycles can be synthesized by using various building blocks such as thiophene, acetylene, benzene, and pyridine [132]. For a better understanding of these conjugated macrocycles, some of them with the interesting self-assembling property and potential in organic electronics are discussed below.
Recent Advances in Non-Platinum-Based Cathode Electrocatalysts for Direct Methanol Fuel Cells
Published in Prasanth Raghavan, Fatima M. J. Jabeen, Ceramic and Specialty Electrolytes for Energy Storage Devices, 2021
Bhagyalakhi Baruah, Ashok Kumar
Macrocyclic compounds are polydentate ligands, in which the donor atoms are either incorporated or attached to a cyclic backbone [57]. Macrocycles are the large molecules that have a minimum of one large ring with nine or more atoms, among which three are donor atoms [58]. Macrocyclic materials have attained much attention due to some remarkable properties, including [57] their ability to differentiate among the same group of metal ions depending upon the ring size and the enhanced stability exhibited by optimally fitted macrocyclic ligands (macrocyclic effect). In 1934, iron phthalocyanine (FePc), the frst transition metal N4 (MN4) macrocycle was discovered by Linstead [59]. Among the various macrocyclics, phthalocyanines (Pc), combined with different transition metals, such as nickel, iron, manganese, zinc, cobalt, and copper, have been extensively studied as cathode electrocatalyst in fuel cells [29, 60] 61, 62]. The cobalt- and copper-based macrocyclic complexes are the most stable, whereas iron- and cobalt-based complexes exhibit good catalytic activity as well as stability [63]. As shown in Figure 11.7, oxygen molecules can interact with the MN4 macrocycle-based catalyst, “end-on” or “side-on” mode, depending on the available coordination sites and energy of d-orbitals of the metal’s center. Moreover, oxygen molecules can interact through the “bridge-cis” and “bridge-trans” configurations, where two metal sites are involved [57]. The binding of oxygen molecules to the catalysts depends on the binding of the d-orbitals in the central metal ion of the macrocycle [64].
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Published in Luis Liz-Marzán, Colloidal Synthesis of Plasmonic Nanometals, 2020
Verónica Montes-García, Jorge Pérez-Juste, Isabel Pastoriza-Santos, Luis M. Liz-Marzán
Macrocyclic molecules are important building blocks within supramolecular chemistry, particularly acting as efficient host molecules in host-guest chemistry for molecular recognition. The nature of these interactions is noncovalent and it can be primarily classified into four types: hydrogen bonding, electrostatic interactions, van der Waals forces, and hydrophobic interactions. Among the various reported macrocycles, cyclodextrins, calixarenes, cucurbiturils, and pillararenes are particularly interesting, because they can be synthesized in relatively high quantities and feature a great versatility towards chemical modification, providing them with tailored recognition properties.
One-pot synthesis, characterization, photocatalytic activity and biological studies of Co(II), Ni(II) and Cu(II) complexes of a tetraazamacrocyclic Schiff base
Published in Journal of Coordination Chemistry, 2023
J. P. Remiya, B. Shyni, T. S. Sikha, U. R. Parvathy
Coordination chemistry of macrocyclic compounds have distinctive properties such as ionic and molecular recognition [1, 2], biomimic functions [3, 4], synthetic ionophores, models for studying magnetic exchange phenomena, therapeutic reagents in chelate therapy for metal intoxication, as a cornerstone in supramolecular chemistry [5, 6], to study host–guest interactions and in phase transfer catalysis [7–9]. The synthesis of metal-containing macrocycles from an in situ one-pot template condensation is a broad subject of chemistry [10, 11]. As a result, template reactions for synthesis of macrocyclic complexes have become ubiquitous, with transition metal ions serving as the templating agent in most cases [12, 13]. Due to developments in bioinorganic chemistry, macrocyclic transition metal complexes have drawn more focus, being recognized as a variety of models for biologically significant species [14, 15].
Experimental and theoretical studies on structure, bonding and luminescence properties of Eu(III) and Tb(III) complexes of a new macrocyclic based 8HQ ligand
Published in Journal of Coordination Chemistry, 2019
Enterobactin, a natural occurring siderophore (Figure 1), is probably the most prominent example of ligand which has high thermodynamic stability [logK = 49 for Fe(III)] that met the above criteria, that has encouraged the synthesis of a wide range of nonnatural compounds used for the binding of metal ions. This incorporates a highly symmetric (C3) serine unit linked to three catechol units through amide spacers. Many biomimetic siderophores have served as excellent chelators for lanthanide luminescence and coordination [13]. Polyaza-macrocycles have a framework similar to L-serine. Incorporation of 8HQ units to the flexible puckered ring of the macrocyclic 9N3 results in the existence of several rotamers/conformers [14]: this has an additional advantage that can adjust its geometry to minimum energy on coordination with metal ions giving extra stability. The macrocycle offers the ability to fine-tune the properties of metal chelation by varying the cycle’s size and flexibility. Very few macrocycles have been described with 8HQ coordinating groups as shown in Figure 2(a–c) [15, 16]. It may be emphasized here that the position of attachment of 8HQ unit plays a significant role in properties and coordination of metal complexes. There are many examples of poly-8HQ chelates in which the 8HQ ring is attached at positions 2, 3, or 7. Tripods incorporating 8HQ substituted at position 5 are scarce. The coordinating property of –N pyridyl group mainly depends upon substitution position at the C-2, C-3, C-5 and/or C-7 in the 8HQ. In the case, where 8HQ is substituted at the position C-2 or C-7, a photoinduced electron transfer (PET) process leads to fluorescence quenching [17].
Macrocyclic copper(II) complexes containing diazacyclam-based ligand: spectral, structural and docking studies
Published in Journal of Coordination Chemistry, 2019
Zahra Mardani, Keyvan Moeini, Majid Darroudi, Cameron Carpenter-Warren, Alexandra M. Z. Slawin, J. Derek Woollins
Macrocycles are an important class of ligands in transition metal chemistry since they can provide beneficial thermodynamic and kinetic properties to their metal complexes [1–4] and increase the ability of coordinated metals to access their less common oxidation states [5]. There is a broad range of applications for these types of ligands and their complexes, such as sensors [6, 7], metal ion-selective reagents [8], nitric oxide [9, 10] and superoxide anion [11] scavengers, precursors for luminescent compound formation, MRI contrast agents and radiopharmaceuticals [12]. Macrocyclic copper complexes can participate in ion exchange reactions [13–15] and also form coordination polymers [14].