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Recent Development in Synthesis of Covalent Organic Frameworks
Published in Tuan Anh Nguyen, Ram K. Gupta, Covalent Organic Frameworks, 2023
Ferda Civan Çavuşoğlu, Gülsüm Özçelik, Şahika Sena Bayazit
Imine-based COFs have been developed for increasing the chemical stability of the crystal structure. The imine-based COFs can be classified into two groups. One of them is the Schiff base reaction group, the other one is the hydrazine type group. Schiff base reaction depends on the co-condensation of aldehydes and amines. Schiff base reactions are known as a part of dynamic covalent chemistry [9]. The positive way of dynamic reaction chemistry is using an acid catalyst enables reversible covalent bonding. COF-300 was synthesized as the first imine-based COF by Yaghi et al. in 2009 [3]. They used Schiff base reaction for the preparation of COF-300. The surface area of COF-300 is 1360 m2/g [12]. Hydrazine type of preparation method is based on the co-condensation reaction of aldehydes and hydrazides. The imine-based COFs are stable in acidic and basic media.
Nano-Bio Hybrid Platform to Meet the Energy Challenge
Published in Keka Talukdar, Nanomaterials-Based Composites for Energy Applications, 2019
Schiff base associates the retinal chromophore to the opsinapoproteinviaLysine-216 amino acid residue. Schiff base is a molecule having N atom bound to a C atom on one side by a C=N double bond and to a carbon on the other side by a C-N single bond. A proton can reversibly attach to the N atom, which acts as a proton stockpile. BR proton pumps with a molecular weight ~ 26.5 kDa are relatively small protein architectures. When the retinal chromophore absorbs a photon, it becomes energized and experiences a conformational change that leads to a change to an advanced energy state which results in the deposited proton to be unconfined. Therefore, in the presence of light, the purple membrane protons get released into the extracellular side of the cell membrane. These protons do not go away, but are directed back into the cell. Protons are positively charged, and intercellular side of the membrane is negatively charged with an electrochemical potential up to 250 millivolts. Therefore, BR is capable of carrying ions against an electrochemical potential with 10,000-fold difference in proton concentration on either side of the membrane [29]. This electrochemical potential is used in photophosphorylation to produce ATP. As the ATP synthesis is done in BR without having no chlorophyll molecule; therefore, the mechanism is known as “non-chlorophyll photosynthesis.”
Amines
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
A Schiff base is the imine derived from reaction of a primary amine and an aromatic aldehyde. Reaction of benzaldehyde and ethanal, for example, leads to PhN=CHCH3. What is the product of the reaction between the Schiff base PhN=CHCH3 and LiAlH4?
Investigation of thermophysical properties of synthesized SA and nano-alumina reinforced polyester composites
Published in Petroleum Science and Technology, 2022
Hakan Şahal, Ercan Aydoğmuş, Hasan Arslanoğlu
Schiff bases are formed by the condensation of primary amines and carbonyl-containing compounds. Such materials exhibit high mechanical resistance, good optoelectronic properties, and thermal stability. They are in the group of important compounds widely used in industrial applications, metallic deactivators, separation processes, catalysis, organic syntheses, and bioinorganic (Mohammed et al., 2010; Li et al., 2003; O’Donnell 2004; Rana et al., 2017; Yuan et al., 2017). The syntheses of the compound containing both Schiff base and sulfonamide fragments have been rarely studied in the literature (Alaghaz et al., 2013). Sulfonamides or sulfa drugs are well-known synthetic antibacterial drugs widely used in human and veterinary medicines (Schebeliski et al., 2018). Sulfonamide derivatives have improved thermal stability and flame retardancy of polymer materials (Yang et al., 2020; Song et al., 2020).
Co(III), Ni(II) and Cu(II) complexes with a tetradentate Schiff base ligand: synthesis, characterization, electrochemical behavior, binding assessment and in vitro cytotoxicity
Published in Journal of Coordination Chemistry, 2022
Marija Mirković, Magdalena Radović, Dalibor Stanković, Sanja Vranješ-Đurić, Drina Janković, Djordje Petrović, Ljiljana E. Mihajlović-Lalić, Željko Prijović, Zorana Milanović
Schiff bases are a well-known class of organic compounds having imine or azomethine (–C = N–) functional groups, commonly formed by condensation of amine NH2 group with active –C = O carbonyl group and having the general structure R1R2C = NR3 (with R3 ≠ H) [1]. They were first reported in 1864 by Hugo Schiff [2]. Schiff base ligands can easily form stable complexes with different metal ions due to their rich coordination chemistry regarding the presence of oxygen and/or nitrogen donor groups. Metal complexes of Schiff bases have been tested and used for a variety of applications in analytical, medicinal, and industrial areas, as well as for essential biological activities including antibacterial, anticancer, antifungal, etc. [3–6].
Anticancer, in vitro cytotoxicity and antimicrobial properties of a Schiff base ligand, 3-((2-(-(1-(2-hydroxyphenyl)ethylidene)amino)ethyl)imino)-N-(p-tolyl)butanamide, and its metal complexes
Published in Journal of Coordination Chemistry, 2021
Structurally, a Schiff base is a nitrogen analogue of a ketone or aldehyde in which the > C=O (carbonyl) group has been replaced by an azomethine or imine [1, 2]. Schiff bases are often used as ligands in the area of coordination chemistry [3]. Over the past ten decades, there have been many reports on their applications [4, 5]. The most common examples of these ligands are those derived from salicylaldehyde. They have been studied widely due to their ease of preparation and their ability to bring changes both satirically and electronically [6]. The chemistry of Schiff bases is very diverse. They can coordinate in a monodentate as well as polydentate [7] fashion to metal ions. Schiff bases and their metal complexes have been studied as antibacterial agents [8–11], antifungal agents [12], antitumor drugs [13] and catalysts [14]. In Schiff base compounds, the imine nitrogen can act as an inter- or intra-molecular hydrogen bond acceptor [15]. Hydrogen-bonding interactions are significant because of their relevance in biological systems. The nature and strength of such interactions between the molecules can influence the uptake of the medicine in the body [16, 17]. The synthesis and characterization of nitrogen and oxygen donor ligands has emerged as one of the main research areas in coordination chemistry [18–20]. Therefore, these complexes have numerous applications [21] in biological [22], analytical [23, 24] and industrial fields [25–27].