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Electrochromism in Conjugated Polymers – Strategies for Complete and Straightforward Color Control
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Anna M. Österholm, D. Eric Shen, John R. Reynolds
Over the last ten years since the publication of the third edition of the Handbook of Conducting Polymers, a significant effort has been devoted to developing cathodically coloring ECPs that exhibit relatively low oxidation potentials allowing them to be switched between their neutral and fully oxidized states easily and repeatedly for thousands to millions of cycles. Specifically, new polymers are designed to be electron-rich and much work has focused around the dioxythiophene class of polymers, though other systems (such as those based on molecular chromophores or metal containing coordination complexes) have also garnered attention. Early research in the field focused heavily on electropolymerization and concurrent film formation, but this has over time been replaced by the synthesis of soluble, processable, and printable macromolecular systems. The utilization of solubilizing side chains has been especially important for leading this shift, and solubility in both non-polar organic solvents as well as in highly polar and aqueous media has been demonstrated. This chapter is not meant to exhaustively review all of the work that has been reported this past decade or go into significant detail about specific polymers or polymer families, but rather we aim to teach general concepts and structure–property relationships that govern color and provide electrochromic switching control. As a result, this chapter will focus almost exclusively on soluble and high molecular weight ECPs.
Structural Design for Molecular Catalysts
Published in Qingmin Ji, Harald Fuchs, Soft Matters for Catalysts, 2019
Qingmin Ji, Qin Tang, Jonathan P. Hill, Katsuhiko Ariga
Catalytic nucleophilic substitution reactions comprise some of the most commonly used catalytic processes in synthetic organic chemistry. When forming a chemical bond, a nucleophile is an electron-rich chemical reactant that is attracted by electron-deficient compounds. The well-known cross-coupling reactions for the formation of single C–C or carbon heteroatom C–X bonds (X = N, O, S, P, Si, B, etc.) include Kumada reaction, Negishi reaction, Stille reaction, Suzuki–Miyaura reaction, Heck reaction, Ulmann coupling, Hiyama-Denmark reaction and Buchwald–Hartwig reaction, etc. [13, 14].
Adsorption of Azorubine E122 dye via Na-mordenite with tryptophan composite: batch adsorption, Box–Behnken design optimisation and antibacterial activity
Published in Environmental Technology, 2023
Hatun H. Alsharief, Nada M. Alatawi, Ameena M. Al-bonayan, Salhah H. Alrefaee, Fawaz A. Saad, M.G. El-Desouky, A.A. El-Bindary
Examining the characterisation and modelling findings of E122 dye uptake by MOR-NH2, it is evident that the functional groups present on the adsorbent amide, hydroxyl, carboxylate and C−O offer minimal chemical interactions. Nevertheless, oxygen atoms in hydroxyl, carboxylate and C−O groups make them competent for forming hydrogen bonds with dye molecules as well as other Van der Waal's forces, such as dipole induced dipole bonds and London dispersion interactions. In short, a closer look suggests that these forces have a significant role in binding the dye. The results of the thermodynamic analysis prove the point perfectly. Moreover, absorption into the solution is commonly restricted due to the low solubility of E122 dye in an area of neutral ionisation resulting from its hydrophobic character. Its molecular design includes several aromatic rings, which adds to its uniqueness. π−π acceptor donor interactions allow polycyclic aromatic compounds to be absorbed with ease. The benzene ring's electron-rich regions attract an adsorbent in stacking formation. For optimum pH, E122 dye uptake with MOR-NH2 is mainly due to the presence of hydrogen bonds, dipole induced dipole connections, London dispersion forces, π−π acceptor donor interactions and the hydrophobic effect Figure 16. After this absorption process, it appears that the surface area and pore volume were reduced hinting at potential pore filling during adsorption [1,47].
An overview: recent development of semiconductor/graphene nanocomposites for photodegradation of phenol and phenolic compounds in aqueous solution
Published in Journal of Asian Ceramic Societies, 2021
Reyhaneh Kaveh, Hassan Alijani
Moreover, graphene can act not only as the electron acceptor and electron storage but also as the electron transport bridge between the semiconductors. For example, Yuan et al. prepared two dimensional 2D ternary MoS2-graphene-ZnIn2S4 composite as highly-effective photocatalyst for solar hydrogen-producing. For the ternary MoS2-graphene-ZnIn2S4 composite, both the MoS2 and the ZnIn2S4 are connected to the graphene. The ZnIn2S4, graphene and MoS2 act as the light-harvesting semiconductor, electron transport bridge and hydrogen evolution reaction catalyst, respectively. In this composite, the CB of ZnIn2S4 is more negative than the graphene/graphene·- (G/G·-) redox potential, so electrons generated from the CB of ZnIn2S4 can be transferred easily to graphene because of the thermodynamic driving force. Further, the G/G·− redox potential is more negative than the CB of MoS2 nanosheets, that is useful for the electron transfer from the electron-rich graphene·− to the CB of MoS2. Consequently, with the efficient electron transport bridge and the large number of active sites on the MoS2, the H2 evolution rate from MoS2-graphene-ZnIn2S4 composite was 22.8 times higher than that of pristine ZnIn2S4 under visible light irradiation [149].
A DFT study on the mechanism of palladium-catalysed tandem reaction of ortho-electron-deficient alkynyl-substituted aryl aldehydes with indoles
Published in Molecular Physics, 2020
Ying-Xue Zhao, Zeng-Xia Zhao, Hong-Xing Zhang
To further interpret the observed chemoselectivity, a general plausible mechanism has been proposed by Zhang and co-workers summarised in Scheme 2 [35]. The reaction starts from intermediate I formed by the coordination of 1a to Pd(II) centre of catalyst Pd(OAc)2. Then a nucleophilic attack by indole 2a on the carbonyl group of I to afford intermediate II with 5-exo-dig cyclic compound formed. Whereafter, it is the key that the electron-withdrawing group on the alkyne and electron-rich indole ring give assistance, from intermediate II to III including C−O bond cleavage and the Pd(OAc)2 coordinated double bond. Intermediate III goes through a cyclisation reaction to give corresponding intermediate IV. Finally, product 3aa is obtained from the cleavage of the carbon-palladium bond in intermediate IV, followed by the palladium (II) species was regenerated to close the catalytic cycle.