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Halogen Bonding in the Decoration of Secondary Coordination Sphere of Zinc(II) and Cadmium(II) Complexes
Publication . Aliyeva, Vusala A.; Paninho, Ana B.; Nunes, Ana V. M.; Karmakar, Anirban; Gurbanov, Atash V.; Rutigliano, Arianna R.; Gallo, Emma; Mahmudov, Kamran T.; Pombeiro, Armando J. L.; LAQV@REQUIMTE; DQ - Departamento de Química; ACS - American Chemical Society
Three new zinc(II) complexes [Zn(H2L3)2(H2O)3] (Zn2), [Zn(H3L2a)(H2O)3]n (Zn3) (H3L2a = 2,4-diiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl)isophthalate) and [Zn(HL4)(DMF)(H2O)]n (Zn4) were synthesized by the reaction of Zn(II) salts with 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl) isophthalic acid (H3L3), 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazineyl) isophthalic acid (H5L2) (in the presence of NH2OH·HCl) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (H3L4), respectively. According to the X-ray structural analysis, the intramolecular resonance-assisted hydrogen bond ring remains intact, with N···O distances of 2.562(5) and 2.573(5) Å in Zn2, 2.603(6) Å in Zn3, and 2.563(8) Å in Zn4. In the crystal packing of Zn3, the cooperation of I···O and I···I types of halogen bonds between tectons leads to a one-dimensional supramolecular polymer, while I···O interactions aggregate 1D chains of coordination polymer Zn4. These new complexes (Zn2, Zn3, and Zn4) and known [Zn(H3L1)(H2O)2]n (Zn1) (H3L1 = 5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene) hydrazineyl)isophthalate), {[Zn(H3L1)(H2O)3]·3H2O}n (Zn5), [Cd(H3L1)(H2O)2]n (Cd1), {[Cd(HL3)(H2O)2(DMF)]·H2O}n (Cd2), [Cd(H3L3)]n (Cd-3), {[Cd2(μ-H2O)2(μ-H2L4)2(H2L4)2]·2H2O}n (Cd4), and {[Cd(H3L1)(H2O)3]·4H2O}n (Cd5) were tested as catalysts in the cycloaddition reaction of CO2 with epoxides in the presence of tetrabutylammonium halides as the cocatalyst. The halogen-bonded catalyst Zn4 is the most efficient one in the presence of tetrabutylammonium bromide by affording a high yield (85-99%) of cyclic carbonates under solvent-free conditions after 48 h at 40 bar and 80 °C.
Solar Fuels Design: Modeling Porous Cathodes for the Production of Carbon-Based Fuels from CO2
Publication . Antunes, Duarte Correia da Fonseca da Silva; Mendes, Manuel; Machado, Ana
The use of fossil fuels is related to several environmental hazards, including global warming, which is caused by an excess of CO_2 in the atmosphere. The reduction of CO_2 emissions from industrial waste gases is crucial for reducing the atmospheric greenhouse effect and, hence, combating climate change. There are several technologies for CO_2 utilisation, powered by electricity derived from solar energy, which can be used to transform fundamental chemical feedstocks like CO_2 and water into clean alternative fuels that improve grid stability, energy security, and environmental advantages. Furthermore, Electrochemical CO_2 Reduction (CO_2R) is one of the most promising strategies to achieve this goal.
A two-dimensional model for porous electrodes developed by C. Ma et al. (2018) to design electrodes for a flow-through, quinone-based battery was adapted in this Thesis to allow the design and optimization of a porous zinc cathode for an electrolizer to perform the co-electrolysis of CO_2 and water. COMSOL® software was used to run the simulations, while model validation was conducted using the experimental data provided by Luo et al. (2019).
The impacts of porosity, pore length, fiber shape geometry, pressure and temperature were explored, and after analyzing the performance of the electrode in each condition, it was possible to optimize each of the previously mentioned parameters and achieve considerably higher current density values (up to 190.06 mA/〖cm〗^2) than those reported in the literature.
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Fundação para a Ciência e a Tecnologia
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3599-PPCDT
Número da atribuição
MIT-EXPL/CS/0052/2021