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SM ISO690:2012 GORBACHEV, Mikhail, ARSENE, Ion, GORINCHOY, Natalia. Influence of nano-particles of TIO2 on relative antioxidant activities of fumaric and dihydroxyfumaric acids: DFT investigation of their reactions with DPPH. In: Achievements and perspectives of modern chemistry, 9-11 octombrie 2019, Chişinău. Chisinau, Republic of Moldova: Tipografia Academiei de Ştiinţe a Moldovei, 2019, p. 105. ISBN 978-9975-62-428-2. |
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Achievements and perspectives of modern chemistry 2019 | |||||
Conferința "International Conference "Achievements and perspectives of modern chemistry"" Chişinău, Moldova, 9-11 octombrie 2019 | |||||
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Pag. 105-105 | |||||
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It has been shown in the work [1] that the interaction between dihydroxyfumaric acid (DHFA) and the stable radical DPPH begins with protonation of the latter and formation of the radical-cation [DPPH-H]*+. Further, [DPPH-H]*+ forms the charge transfer complex (CTC) with the anion of DHFA. As a result of this process the unpaired electron of DPPH will be localized on the atoms of the anionic fragment of the CTC. Our DFT computational data received by means of the program GAUSSIAN 09 (B3LYP, 6-31G) show that the same localization of the unpaired electron takes place also in the CTC between [DPPH-H]*+ and the anion of fumaric acid (FA). Here we present the results describing the influence of the nano-cluster H2Ti4O9 on the redistribution of the electronic density in the both above CTCs (Figure below). One can see that in the case of DHFA (system A) the main part of electronic density of the unpaired electron is localized on the atoms of DHFA, while in the case of FA it is significantly displaced onto the H2Ti4O9 nano-cluster. It is well known that the UV irradiation of TiO2 nanoparticles leads to the formation of free electrons and positively charged holes on their surface. It is clear that only for the DPPH&FA&H2Ti4O9 system the electronic density of its unpaired electron can recombine with these photo-generated particles. Thus, we can draw the following conclusion. Nano-particles of TiO2 enhance the antioxidant activity of those organic compounds for which the topology of their molecular orbitals allows the transfer of the electronic density to the TiO2 nanoparticles. |
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