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Stanković, B; Jovanović, J; Adnađević, B The kinetics of non-isothermal dehydration of equilibrium swollen Ca-alginate hydrogel Journal Article Journal of Thermal Analysis and Calorimetry, 142 (5), pp. 2123-2129, 2020. @article{Stanković20202123, title = {The kinetics of non-isothermal dehydration of equilibrium swollen Ca-alginate hydrogel}, author = {B Stanković and J Jovanović and B Adnađević}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088256033&doi=10.1007%2fs10973-020-10020-6&partnerID=40&md5=e3b9fed5a780db8cdea4a0d8f8bec2f6}, doi = {10.1007/s10973-020-10020-6}, year = {2020}, date = {2020-01-01}, journal = {Journal of Thermal Analysis and Calorimetry}, volume = {142}, number = {5}, pages = {2123-2129}, abstract = {Non-isothermal dehydration of Ca-alginate hydrogel was investigated for the first time. Thermogravimetric dehydration curves were recorded at heating rates from 5 to 20 K min−1 in the temperature range from 300 to 450 K. The dependence of apparent activation energy on the degree of dehydration was determined by the Friedman’s differential isoconversion method. The experimental conversion curves of dehydration are fully fitted with the statistical model of hydrogel dehydration. The values of the parameters of the statistical model and their changes with the heating rate were determined. The rate constant as the function of temperature was calculated at all heating rates, and it was found that these dependencies obey the Arrhenius equation. From the values of rate constant, the changes in the kinetic parameters (activation energy and pre-exponential factor) of non-isothermal dehydration of Ca-alginate hydrogel with temperature and dehydration degree were calculated. The obtained results indicate the existence of two phase states of water absorbed on the hydrogel. © 2020, Akadémiai Kiadó, Budapest, Hungary.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Non-isothermal dehydration of Ca-alginate hydrogel was investigated for the first time. Thermogravimetric dehydration curves were recorded at heating rates from 5 to 20 K min−1 in the temperature range from 300 to 450 K. The dependence of apparent activation energy on the degree of dehydration was determined by the Friedman’s differential isoconversion method. The experimental conversion curves of dehydration are fully fitted with the statistical model of hydrogel dehydration. The values of the parameters of the statistical model and their changes with the heating rate were determined. The rate constant as the function of temperature was calculated at all heating rates, and it was found that these dependencies obey the Arrhenius equation. From the values of rate constant, the changes in the kinetic parameters (activation energy and pre-exponential factor) of non-isothermal dehydration of Ca-alginate hydrogel with temperature and dehydration degree were calculated. The obtained results indicate the existence of two phase states of water absorbed on the hydrogel. © 2020, Akadémiai Kiadó, Budapest, Hungary. |
Lačnjevac, U; Vasilić, R; Dobrota, A; Đurđić, S; Tomanec, O; Zbořil, R; Mohajernia, S; Nguyen, N T; Skorodumova, N; Manojlović, D; Elezović, N; Pašti, I; Schmuki, P High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2nanotube arrays as interactive supports for Ir nanoparticles Journal Article Journal of Materials Chemistry A, 8 (43), pp. 22773-22790, 2020. @article{Lačnjevac202022773, title = {High-performance hydrogen evolution electrocatalysis using proton-intercalated TiO2nanotube arrays as interactive supports for Ir nanoparticles}, author = {U Lačnjevac and R Vasilić and A Dobrota and S Đurđić and O Tomanec and R Zbořil and S Mohajernia and N T Nguyen and N Skorodumova and D Manojlović and N Elezović and I Pašti and P Schmuki}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096105811&doi=10.1039%2fd0ta07492f&partnerID=40&md5=a143ddd17acc1ebc897636d998ae37e3}, doi = {10.1039/d0ta07492f}, year = {2020}, date = {2020-01-01}, journal = {Journal of Materials Chemistry A}, volume = {8}, number = {43}, pages = {22773-22790}, abstract = {Developing ultraefficient electrocatalytic materials for the hydrogen evolution reaction (HER) with low content of expensive platinum group metals (PGMs) via low-energy-input procedures is the key to the successful commercialization of green water electrolysis technologies for sustainable production of high-purity hydrogen. In this study, we report a facile room-temperature synthesis of ultrafine metallic Ir nanoparticles on conductive, proton-intercalated TiO2 nanotube (H-TNT) arrays via galvanic displacement. A series of experiments demonstrate that a controlled transformation of the H-TNT surface microstructure from neat open-top tubes to disordered nanostripe bundles ("nanograss") is highly beneficial for providing an abundance of exposed Ir active sites. Consequently, for nanograss-engineered composites, outstanding HER activity metrics are achieved even at very low Ir(iii) precursor concentrations. An optimum Ir@TNT cathode loaded with 5.7 μgIr cm-2 exhibits an overpotential of -63 mV at -100 mA cm-2 and a mass activity of 34 A mgIr-1 at -80 mV under acidic conditions, along with excellent catalytic durability and structural integrity. Density functional theory (DFT) simulations reveal that the hydrogen-rich TiO2 surface not only stabilizes the deposited Ir and weakens its H binding strength to a moderate intensity, but also actively takes part in the HER mechanism by refreshing the Ir catalytic sites near the Ir|H-TiO2 interface, thus substantially promoting H2 generation. The comprehensive characterization combined with theory provides an in-depth understanding of the electrocatalytic behavior of H-TNT supported PGM nanoparticles and demonstrates their high potential as competitive electrocatalyst systems for the HER. This journal is © The Royal Society of Chemistry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Developing ultraefficient electrocatalytic materials for the hydrogen evolution reaction (HER) with low content of expensive platinum group metals (PGMs) via low-energy-input procedures is the key to the successful commercialization of green water electrolysis technologies for sustainable production of high-purity hydrogen. In this study, we report a facile room-temperature synthesis of ultrafine metallic Ir nanoparticles on conductive, proton-intercalated TiO2 nanotube (H-TNT) arrays via galvanic displacement. A series of experiments demonstrate that a controlled transformation of the H-TNT surface microstructure from neat open-top tubes to disordered nanostripe bundles ("nanograss") is highly beneficial for providing an abundance of exposed Ir active sites. Consequently, for nanograss-engineered composites, outstanding HER activity metrics are achieved even at very low Ir(iii) precursor concentrations. An optimum Ir@TNT cathode loaded with 5.7 μgIr cm-2 exhibits an overpotential of -63 mV at -100 mA cm-2 and a mass activity of 34 A mgIr-1 at -80 mV under acidic conditions, along with excellent catalytic durability and structural integrity. Density functional theory (DFT) simulations reveal that the hydrogen-rich TiO2 surface not only stabilizes the deposited Ir and weakens its H binding strength to a moderate intensity, but also actively takes part in the HER mechanism by refreshing the Ir catalytic sites near the Ir|H-TiO2 interface, thus substantially promoting H2 generation. The comprehensive characterization combined with theory provides an in-depth understanding of the electrocatalytic behavior of H-TNT supported PGM nanoparticles and demonstrates their high potential as competitive electrocatalyst systems for the HER. This journal is © The Royal Society of Chemistry. |
Simpson, M; Nötzold, M; Schmidt-May, A; Michaelsen, T; Bastian, B; Meyer, J; Wild, R; Gianturco, F A; Milovanović, M; Kokoouline, V; Wester, R Threshold photodetachment spectroscopy of the astrochemical anion CN Journal Article The Journal of chemical physics, 153 (18), pp. 184309, 2020. @article{Simpson2020184309, title = {Threshold photodetachment spectroscopy of the astrochemical anion CN}, author = {M Simpson and M Nötzold and A Schmidt-May and T Michaelsen and B Bastian and J Meyer and R Wild and F A Gianturco and M Milovanović and V Kokoouline and R Wester}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096153521&doi=10.1063%2f5.0029841&partnerID=40&md5=584b9b90faed6bdb8be45e0555f890e0}, doi = {10.1063/5.0029841}, year = {2020}, date = {2020-01-01}, journal = {The Journal of chemical physics}, volume = {153}, number = {18}, pages = {184309}, abstract = {Threshold photodetachment spectroscopy has been performed on the molecular anion CN- at both 16(1) K and 295(2) K in a 22-pole ion trap and at 295(2) K from a pulsed ion beam. The spectra show a typical energy dependence of the detachment cross section yielding a determination of the electron affinity of CN to greater precision than has previously been known at 31 163(16) cm-1 [3.864(2) eV]. Allowed s-wave detachment is observed for CN-, but the dependence of the photodetachment cross section near the threshold is perturbed by the long-range interaction between the permanent dipole moment of CN and the outgoing electron. Furthermore, we observe a temperature dependence of the cross section near the threshold, which we attribute to a reduction of the effective permanent dipole due to higher rotational excitation at higher temperatures.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Threshold photodetachment spectroscopy has been performed on the molecular anion CN- at both 16(1) K and 295(2) K in a 22-pole ion trap and at 295(2) K from a pulsed ion beam. The spectra show a typical energy dependence of the detachment cross section yielding a determination of the electron affinity of CN to greater precision than has previously been known at 31 163(16) cm-1 [3.864(2) eV]. Allowed s-wave detachment is observed for CN-, but the dependence of the photodetachment cross section near the threshold is perturbed by the long-range interaction between the permanent dipole moment of CN and the outgoing electron. Furthermore, we observe a temperature dependence of the cross section near the threshold, which we attribute to a reduction of the effective permanent dipole due to higher rotational excitation at higher temperatures. |
Milakin, K A; Gavrilov, N; Pašti, I A; Morávková, Z; Acharya, U; Unterweger, C; Breitenbach, S; Zhigunov, A; Bober, P Polyaniline-metal organic framework (Fe-BTC) composite for electrochemical applications Journal Article Polymer, 208 , 2020. @article{Milakin2020, title = {Polyaniline-metal organic framework (Fe-BTC) composite for electrochemical applications}, author = {K A Milakin and N Gavrilov and I A Pašti and Z Morávková and U Acharya and C Unterweger and S Breitenbach and A Zhigunov and P Bober}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090323515&doi=10.1016%2fj.polymer.2020.122945&partnerID=40&md5=be56e127fd0360a7e9ab7a1dde608c8a}, doi = {10.1016/j.polymer.2020.122945}, year = {2020}, date = {2020-01-01}, journal = {Polymer}, volume = {208}, abstract = {Polyaniline-metal organic framework (PANI/Fe-BTC) composites were prepared by oxidative polymerization of aniline in the presence of Fe-BTC, using various monomer:Fe-BTC ratios. Introduction of Fe-BTC into polyaniline-based materials led to significant reduction of their thermal stability starting from 2 wt% Fe-BTC content, which further decreased with decreasing monomer concentration in the initial reaction mixture. Fe-BTC being a low conducting component (2 × 10−10 S cm−1) in comparison to PANI (6 S cm−1) was found to negatively affect conductivity of PANI/Fe-BTC composites. Conductivity values gradually lowered with the decrease of aniline fraction in the polymerization mixture: from 4 S cm−1 for the composite prepared with 80 wt% of the monomer in the reaction mixture to 0.04 S cm−1 for the 20 wt% of the monomer. Decreasing aniline fraction during the materials preparation resulted in a smaller amount of PANI particles on the surface of Fe-BTC. When aniline concentration reached 20 wt%, the morphology of the composite was similar to the one of pristine Fe-BTC. These PANI particles were found to be mainly determining specific surface area of PANI/Fe-BTC composites due to the fact that specific surface area of the products decreased with decreasing monomer fraction from 55 m2 g−1 for pristine PANI to 8 m2 g−1 for PANI(20%)/Fe-BTC. XRD data showed that the composition of PANI(20%)/Fe-BTC material corresponds to a saturation point, after which aggregation of PANI chains occurs. Spectroscopic analysis revealed that PANI on the Fe-BTC interface is overoxidized and partially doped by Fe-BTC. These PANI-Fe-BTC interactions were found to affect electrochemical properties of the composites. Materials prepared using lower monomer fraction in the initial reaction medium were characterized by more favorable reduction transitions which happened at more positive potentials. Increasing aniline:Fe-BTC ratio was also found to enhance gravimetric capacitance of the composites, reaching 346 F g−1 at 20 mV s−1. Moreover, improved pseudo-Faradaic current response and substantially better reversibility during electrochemical characterization shown for PANI/Fe-BTC compared to pristine PANI can be advantageous for energy applications. © 2020 Elsevier Ltd}, keywords = {}, pubstate = {published}, tppubtype = {article} } Polyaniline-metal organic framework (PANI/Fe-BTC) composites were prepared by oxidative polymerization of aniline in the presence of Fe-BTC, using various monomer:Fe-BTC ratios. Introduction of Fe-BTC into polyaniline-based materials led to significant reduction of their thermal stability starting from 2 wt% Fe-BTC content, which further decreased with decreasing monomer concentration in the initial reaction mixture. Fe-BTC being a low conducting component (2 × 10−10 S cm−1) in comparison to PANI (6 S cm−1) was found to negatively affect conductivity of PANI/Fe-BTC composites. Conductivity values gradually lowered with the decrease of aniline fraction in the polymerization mixture: from 4 S cm−1 for the composite prepared with 80 wt% of the monomer in the reaction mixture to 0.04 S cm−1 for the 20 wt% of the monomer. Decreasing aniline fraction during the materials preparation resulted in a smaller amount of PANI particles on the surface of Fe-BTC. When aniline concentration reached 20 wt%, the morphology of the composite was similar to the one of pristine Fe-BTC. These PANI particles were found to be mainly determining specific surface area of PANI/Fe-BTC composites due to the fact that specific surface area of the products decreased with decreasing monomer fraction from 55 m2 g−1 for pristine PANI to 8 m2 g−1 for PANI(20%)/Fe-BTC. XRD data showed that the composition of PANI(20%)/Fe-BTC material corresponds to a saturation point, after which aggregation of PANI chains occurs. Spectroscopic analysis revealed that PANI on the Fe-BTC interface is overoxidized and partially doped by Fe-BTC. These PANI-Fe-BTC interactions were found to affect electrochemical properties of the composites. Materials prepared using lower monomer fraction in the initial reaction medium were characterized by more favorable reduction transitions which happened at more positive potentials. Increasing aniline:Fe-BTC ratio was also found to enhance gravimetric capacitance of the composites, reaching 346 F g−1 at 20 mV s−1. Moreover, improved pseudo-Faradaic current response and substantially better reversibility during electrochemical characterization shown for PANI/Fe-BTC compared to pristine PANI can be advantageous for energy applications. © 2020 Elsevier Ltd |
Stanković, V V; Ristić, M M; Vojnović, M M; Aoneas, M M; Poparić, G B Ionization and Electronic State Excitation of CO2 in Radio-frequency Electric Field Journal Article Plasma Chemistry and Plasma Processing, 40 (6), pp. 1621-1637, 2020. @article{Stanković20201621, title = {Ionization and Electronic State Excitation of CO2 in Radio-frequency Electric Field}, author = {V V Stanković and M M Ristić and M M Vojnović and M M Aoneas and G B Poparić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088316562&doi=10.1007%2fs11090-020-10106-x&partnerID=40&md5=0476febf1f55fb24543585a15d1afef0}, doi = {10.1007/s11090-020-10106-x}, year = {2020}, date = {2020-01-01}, journal = {Plasma Chemistry and Plasma Processing}, volume = {40}, number = {6}, pages = {1621-1637}, abstract = {The rate coefficients for the electron impact ionization and electronic state excitation of the CO2 molecule are calculated in non-equilibrium conditions in the presence of time-dependent electric field. A Monte Carlo simulation has been employed in order to determine non-equilibrium electron energy distribution functions in the CO2 gas, within one period of time-dependent radio-frequency (RF) electric field. By using the distribution functions, ionization rate coefficients for the CO2 molecule have been obtained within one period in RF frequency range at effective reduced electric field up to 500 Td. All obtained rate coefficients have been period averaged, as they can be of use in practical applications in the modeling of RF discharges in CO2. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The rate coefficients for the electron impact ionization and electronic state excitation of the CO2 molecule are calculated in non-equilibrium conditions in the presence of time-dependent electric field. A Monte Carlo simulation has been employed in order to determine non-equilibrium electron energy distribution functions in the CO2 gas, within one period of time-dependent radio-frequency (RF) electric field. By using the distribution functions, ionization rate coefficients for the CO2 molecule have been obtained within one period in RF frequency range at effective reduced electric field up to 500 Td. All obtained rate coefficients have been period averaged, as they can be of use in practical applications in the modeling of RF discharges in CO2. © 2020, Springer Science+Business Media, LLC, part of Springer Nature. |
Todorović, M N; Radenković, M B; Onjia, A E; Ignjatović, L M Characterization of PM2.5 sources in a Belgrade suburban area: a multi-scale receptor-oriented approach Journal Article Environmental Science and Pollution Research, 27 (33), pp. 41717-41730, 2020. @article{Todorović202041717, title = {Characterization of PM2.5 sources in a Belgrade suburban area: a multi-scale receptor-oriented approach}, author = {M N Todorović and M B Radenković and A E Onjia and L M Ignjatović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088241346&doi=10.1007%2fs11356-020-10129-z&partnerID=40&md5=c705a67aa3f696f517479100df237de2}, doi = {10.1007/s11356-020-10129-z}, year = {2020}, date = {2020-01-01}, journal = {Environmental Science and Pollution Research}, volume = {27}, number = {33}, pages = {41717-41730}, abstract = {Designated as the most harmful for health, PM2.5 aerosol fraction was a subject of our study. It was collected for all four seasons during 2014/15 in the suburban area of Belgrade (Serbia) and analysed for Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, As, Ba and Pb elements and for NH4+, NO3− and SO42− ions by particle-induced X-ray emission and ion chromatography techniques, respectively. Obtained concentrations have been treated by a combination of several receptor-oriented models to reveal source contributions to the suburban PM2.5 at different spatial scales. Applied positive matrix factorization analysis indicated five main groups of emission sources: biomass burning (14.5%), traffic (3.9%), regional combustion/secondary sulphates (28.8%), local combustion/secondary nitrates (29.7%) and soil (5.4%). Local heating units had been pointed out as dominant contributors by long-range transport and ground-wind circulation analyses. Air masses circulating over the Balkan Peninsula denoted regional emissions as responsible for the high concentrations of secondary sulphates. Local and long-range transport analyses combined suggested that the BB and the LC/NO3 originated from the wider urban area. Several Saharan dust episodes were detected as well. Presented results might be a basis for the development of air pollution mitigation strategies in the continental Balkan area, considered one of the most polluted and under-investigated European regions. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Designated as the most harmful for health, PM2.5 aerosol fraction was a subject of our study. It was collected for all four seasons during 2014/15 in the suburban area of Belgrade (Serbia) and analysed for Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, As, Ba and Pb elements and for NH4+, NO3− and SO42− ions by particle-induced X-ray emission and ion chromatography techniques, respectively. Obtained concentrations have been treated by a combination of several receptor-oriented models to reveal source contributions to the suburban PM2.5 at different spatial scales. Applied positive matrix factorization analysis indicated five main groups of emission sources: biomass burning (14.5%), traffic (3.9%), regional combustion/secondary sulphates (28.8%), local combustion/secondary nitrates (29.7%) and soil (5.4%). Local heating units had been pointed out as dominant contributors by long-range transport and ground-wind circulation analyses. Air masses circulating over the Balkan Peninsula denoted regional emissions as responsible for the high concentrations of secondary sulphates. Local and long-range transport analyses combined suggested that the BB and the LC/NO3 originated from the wider urban area. Several Saharan dust episodes were detected as well. Presented results might be a basis for the development of air pollution mitigation strategies in the continental Balkan area, considered one of the most polluted and under-investigated European regions. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. |
Mišurović, J; Mojović, M; Marjanović, B; Vulić, P; Ćirić-Marjanović, G Magnetite nanoparticles-catalyzed synthesis of conductive poly(p-aminodiphenylamine) Journal Article Synthetic Metals, 269 , 2020. @article{Mišurović2020, title = {Magnetite nanoparticles-catalyzed synthesis of conductive poly(p-aminodiphenylamine)}, author = {J Mišurović and M Mojović and B Marjanović and P Vulić and G Ćirić-Marjanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091590368&doi=10.1016%2fj.synthmet.2020.116577&partnerID=40&md5=9d58d17505031d1fc2956c8449632aa1}, doi = {10.1016/j.synthmet.2020.116577}, year = {2020}, date = {2020-01-01}, journal = {Synthetic Metals}, volume = {269}, abstract = {Para-aminodiphenylamine (p-ADPA) was successfully polymerized by simple, economical and environmentally improved procedure. Magnetite nanoparticles (Fe3O4 NPs) were found to successfully catalyze the oxidation of p-ADPA in the presence of hydrogen peroxide (H2O2), an eco-friendly and clean oxidant, with a very small amount of ammonium peroxydisulfate (APS) as an initiator. In this manner, the amount of by-products occurring during the reaction is drastically reduced. The oxidation of p-ADPA proceeded also in the absence of Fe3O4 NPs, but far more slowly than the catalyzed process. The influence of the mass ratio Fe3O4NPs/p-ADPA on the properties of products was systematically studied by different characterization techniques. Spectroscopic measurements (UV-Vis-NIR, FTIR, Raman, EPR) indicate that the polymerization products are polyaniline emeraldine salt-like polymers and their measured electrical conductivity is one of the highest values reported in the literature for p-ADPA oligomerization/polymerization products (1.8∙10-2 S cm-1). X-ray powder diffraction (XRPD) measurements revealed highly crystalline structure of Poly(p-ADPA) samples synthesized with Fe3O4 NPs, while scanning electron microscopy (SEM) showed layered and prismatic-shaped particles as prevailing in their morphology. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Para-aminodiphenylamine (p-ADPA) was successfully polymerized by simple, economical and environmentally improved procedure. Magnetite nanoparticles (Fe3O4 NPs) were found to successfully catalyze the oxidation of p-ADPA in the presence of hydrogen peroxide (H2O2), an eco-friendly and clean oxidant, with a very small amount of ammonium peroxydisulfate (APS) as an initiator. In this manner, the amount of by-products occurring during the reaction is drastically reduced. The oxidation of p-ADPA proceeded also in the absence of Fe3O4 NPs, but far more slowly than the catalyzed process. The influence of the mass ratio Fe3O4NPs/p-ADPA on the properties of products was systematically studied by different characterization techniques. Spectroscopic measurements (UV-Vis-NIR, FTIR, Raman, EPR) indicate that the polymerization products are polyaniline emeraldine salt-like polymers and their measured electrical conductivity is one of the highest values reported in the literature for p-ADPA oligomerization/polymerization products (1.8∙10-2 S cm-1). X-ray powder diffraction (XRPD) measurements revealed highly crystalline structure of Poly(p-ADPA) samples synthesized with Fe3O4 NPs, while scanning electron microscopy (SEM) showed layered and prismatic-shaped particles as prevailing in their morphology. © 2020 Elsevier B.V. |
Rajić, V; Simatović, Stojković I; Veselinović, L; Čavor, J B; Novaković, M; Popović, M; Škapin, S D; Mojović, M; Stojadinović, S; Rac, V; Častvan, I J; Marković, S Bifunctional catalytic activity of Zn1-: XFexO toward the OER/ORR: Seeking an optimal stoichiometry Journal Article Physical Chemistry Chemical Physics, 22 (38), pp. 22078-22095, 2020. @article{Rajić202022078, title = {Bifunctional catalytic activity of Zn1-: XFexO toward the OER/ORR: Seeking an optimal stoichiometry}, author = {V Rajić and I Stojković Simatović and L Veselinović and J B Čavor and M Novaković and M Popović and S D Škapin and M Mojović and S Stojadinović and V Rac and I J Častvan and S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092681262&doi=10.1039%2fd0cp03377d&partnerID=40&md5=40bcf6262611a1231b60b7ecb5910e44}, doi = {10.1039/d0cp03377d}, year = {2020}, date = {2020-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, number = {38}, pages = {22078-22095}, abstract = {Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1-xFexO}, keywords = {}, pubstate = {published}, tppubtype = {article} } Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1-xFexO |
Milovanović, B; Stanković, I M; Petković, M; Etinski, M Modulating Excited Charge-Transfer States of G-Quartet Self-Assemblies by Earth Alkaline Cations and Hydration Journal Article The journal of physical chemistry. A, 124 (40), pp. 8101-8111, 2020. @article{Milovanović20208101, title = {Modulating Excited Charge-Transfer States of G-Quartet Self-Assemblies by Earth Alkaline Cations and Hydration}, author = {B Milovanović and I M Stanković and M Petković and M Etinski}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092749673&doi=10.1021%2facs.jpca.0c05022&partnerID=40&md5=ba932b0d2b08f6b231e0d9df6c2391cf}, doi = {10.1021/acs.jpca.0c05022}, year = {2020}, date = {2020-01-01}, journal = {The journal of physical chemistry. A}, volume = {124}, number = {40}, pages = {8101-8111}, abstract = {Guanine self-assemblies are promising supramolecular platforms for optoelectronic applications. The study (Hua et al., J. Phys. Chem. C2012, 116, 14,682-14,689) reported that alkaline cations cannot modulate the electronic absorption spectrum of G-quadruplexes, although a cation effect is observable during electronic relaxation due to different mobility of Na+ and K+ cations. In this work, we theoretically examined whether divalent Mg2+ and Ca2+ cations and hydration might shift excited charge-transfer states of a cation-templated stacked G-quartet to the absorption red tail. Our results showed that earth alkaline cations blue-shifted nπ* states and stabilized charge-transfer ππ* states relative to those of complexes with alkaline cations, although the number of charge-separation states was not significantly modified. Earth alkaline cations were not able to considerably increase the amount of charge-transfer states below the Lb excitonic states. Hydration shifted charge-transfer states of the Na+-coordinated G-octet to the absorption red tail, although this part of the spectrum was still dominated by monomer-like excitations. We found G-octet electron detachment states at low excitation energies in aqueous solution. These states were distributed over a broad range of excitation energies and could be responsible for oxidative damage observed upon UV irradiation of biological G-quadruplexes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Guanine self-assemblies are promising supramolecular platforms for optoelectronic applications. The study (Hua et al., J. Phys. Chem. C2012, 116, 14,682-14,689) reported that alkaline cations cannot modulate the electronic absorption spectrum of G-quadruplexes, although a cation effect is observable during electronic relaxation due to different mobility of Na+ and K+ cations. In this work, we theoretically examined whether divalent Mg2+ and Ca2+ cations and hydration might shift excited charge-transfer states of a cation-templated stacked G-quartet to the absorption red tail. Our results showed that earth alkaline cations blue-shifted nπ* states and stabilized charge-transfer ππ* states relative to those of complexes with alkaline cations, although the number of charge-separation states was not significantly modified. Earth alkaline cations were not able to considerably increase the amount of charge-transfer states below the Lb excitonic states. Hydration shifted charge-transfer states of the Na+-coordinated G-octet to the absorption red tail, although this part of the spectrum was still dominated by monomer-like excitations. We found G-octet electron detachment states at low excitation energies in aqueous solution. These states were distributed over a broad range of excitation energies and could be responsible for oxidative damage observed upon UV irradiation of biological G-quadruplexes. |
Milenković, D A; Dimić, D S; Avdović, E H; Marković, Z S Several coumarin derivatives and their Pd(ii) complexes as potential inhibitors of the main protease of SARS-CoV-2, anin silicoapproach Journal Article RSC Advances, 10 (58), pp. 35099-35108, 2020. @article{Milenković202035099, title = {Several coumarin derivatives and their Pd(ii) complexes as potential inhibitors of the main protease of SARS-CoV-2, anin silicoapproach}, author = {D A Milenković and D S Dimić and E H Avdović and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092592073&doi=10.1039%2fd0ra07062a&partnerID=40&md5=45250d66c08a2db58750074fc5daf92c}, doi = {10.1039/d0ra07062a}, year = {2020}, date = {2020-01-01}, journal = {RSC Advances}, volume = {10}, number = {58}, pages = {35099-35108}, abstract = {The global pandemic of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused many fatalities among people and significantly influenced the global economy. Since efficient treatment is not available, the computational methods in biology and chemistry are a promising starting point towards adequate medication. Three previously synthesized coumarin derivatives and their Pd(ii) complexes were examined for the binding affinity towards the Mproprotein of SARS-CoV-2 by molecular docking and compared to two Food and Drug Administration (FDA) drugs,cinanserinandchloroquine. All of the investigated compounds bind to the active position of the mentioned protein. Coumarin-Pd(ii) complexes showed higher binding affinities compared to the approved drugs. The bindings of the bis(3-(1-((3-chlorophenyl)amino)ethylidene)-chroman-2,4-dione) palladium(ii) complex, its corresponding ligand, andcinanserinto SARS-CoV-2 Mprowere further subjected to the molecular dynamics simulations. The binding free energies, computed by MM/PBSA approach were analyzed in detail and the importance of specific interactions outlined. These results showed that the molecules bearing structural similarity to the approved drugs and their complexes have the potential to inhibit the functional activity of SARS-CoV-2 protease and further experimental studies should be undertaken. © The Royal Society of Chemistry 2020.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The global pandemic of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) caused many fatalities among people and significantly influenced the global economy. Since efficient treatment is not available, the computational methods in biology and chemistry are a promising starting point towards adequate medication. Three previously synthesized coumarin derivatives and their Pd(ii) complexes were examined for the binding affinity towards the Mproprotein of SARS-CoV-2 by molecular docking and compared to two Food and Drug Administration (FDA) drugs,cinanserinandchloroquine. All of the investigated compounds bind to the active position of the mentioned protein. Coumarin-Pd(ii) complexes showed higher binding affinities compared to the approved drugs. The bindings of the bis(3-(1-((3-chlorophenyl)amino)ethylidene)-chroman-2,4-dione) palladium(ii) complex, its corresponding ligand, andcinanserinto SARS-CoV-2 Mprowere further subjected to the molecular dynamics simulations. The binding free energies, computed by MM/PBSA approach were analyzed in detail and the importance of specific interactions outlined. These results showed that the molecules bearing structural similarity to the approved drugs and their complexes have the potential to inhibit the functional activity of SARS-CoV-2 protease and further experimental studies should be undertaken. © The Royal Society of Chemistry 2020. |
Janićijević, D; Uskoković-Marković, S; Ranković, D; Milenković, M; Jevremović, A; Vasiljević, Nedić B; Milojević-Rakić, M; Bajuk-Bogdanović, D Double active BEA zeolite/silver tungstophosphates – Antimicrobial effects and pesticide removal Journal Article Science of the Total Environment, 735 , 2020. @article{Janićijević2020, title = {Double active BEA zeolite/silver tungstophosphates – Antimicrobial effects and pesticide removal}, author = {D Janićijević and S Uskoković-Marković and D Ranković and M Milenković and A Jevremović and B Nedić Vasiljević and M Milojević-Rakić and D Bajuk-Bogdanović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085236820&doi=10.1016%2fj.scitotenv.2020.139530&partnerID=40&md5=8e428aeddbb498a0dca4e994762a6904}, doi = {10.1016/j.scitotenv.2020.139530}, year = {2020}, date = {2020-01-01}, journal = {Science of the Total Environment}, volume = {735}, abstract = {Novel composites of BEA zeolite and silver tungstophosphate were prepared by different procedures: two-step impregnation, ion-exchange, and as physical mixtures with varying component mass ratios. Composites were characterized using Atomic force microscopy, Infrared, Raman and Atomic absorption spectroscopy, and results were related to adsorption properties and antimicrobial efficiencies of the composites. Prepared samples were tested as antimicrobial agents for fungal and different bacterial strains, as well as for adsorbents for pesticide nicosulfuron in aqueous solutions by using High-performance liquid chromatography. Experimental conditions for batch adsorption testing were optimized in order to efficiently eliminate nicosulfuron from aqueous solutions, while enabling antimicrobial activity of these advanced materials. Antimicrobial efficiency of composites was verified, and indicated that silver ion persistence in the solid phase is of utmost significance for the antimicrobial activity. Spectroscopic investigation revealed interaction of the silver tungstophosphate active phase and the zeolite framework, giving evidence of uniform distribution of active sites in the synthesized materials that proved to be essential for adsorption application. The best obtained adsorption capacity, as well as highest antimicrobial efficiency, is found for composite samples prepared by two-step impregnation with (BEA: silver tungstophosphate) mass ratio 2:1. The amount of nicosulfuron removed from water suspension was 38.2 mg per gram of composite, and the minimum inhibitory concentration determined for all investigated gram-negative bacteria was 125 μg mL−1. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Novel composites of BEA zeolite and silver tungstophosphate were prepared by different procedures: two-step impregnation, ion-exchange, and as physical mixtures with varying component mass ratios. Composites were characterized using Atomic force microscopy, Infrared, Raman and Atomic absorption spectroscopy, and results were related to adsorption properties and antimicrobial efficiencies of the composites. Prepared samples were tested as antimicrobial agents for fungal and different bacterial strains, as well as for adsorbents for pesticide nicosulfuron in aqueous solutions by using High-performance liquid chromatography. Experimental conditions for batch adsorption testing were optimized in order to efficiently eliminate nicosulfuron from aqueous solutions, while enabling antimicrobial activity of these advanced materials. Antimicrobial efficiency of composites was verified, and indicated that silver ion persistence in the solid phase is of utmost significance for the antimicrobial activity. Spectroscopic investigation revealed interaction of the silver tungstophosphate active phase and the zeolite framework, giving evidence of uniform distribution of active sites in the synthesized materials that proved to be essential for adsorption application. The best obtained adsorption capacity, as well as highest antimicrobial efficiency, is found for composite samples prepared by two-step impregnation with (BEA: silver tungstophosphate) mass ratio 2:1. The amount of nicosulfuron removed from water suspension was 38.2 mg per gram of composite, and the minimum inhibitory concentration determined for all investigated gram-negative bacteria was 125 μg mL−1. © 2020 Elsevier B.V. |
Mitić, M; Milovanović, M; Veljković, F; Perić-Grujić, A; Veličković, S; Jerosimić, S Theoretical and experimental study of small potassium-bromide KnBr(0,1+) (n = 2–6) and KnBrn-1(0,1+) (n = 3–5) clusters Journal Article Journal of Alloys and Compounds, 835 , 2020. @article{Mitić2020, title = {Theoretical and experimental study of small potassium-bromide KnBr(0,1+) (n = 2–6) and KnBrn-1(0,1+) (n = 3–5) clusters}, author = {M Mitić and M Milovanović and F Veljković and A Perić-Grujić and S Veličković and S Jerosimić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084049008&doi=10.1016%2fj.jallcom.2020.155301&partnerID=40&md5=654ac78bc3913ac2d7a52306ac4bab64}, doi = {10.1016/j.jallcom.2020.155301}, year = {2020}, date = {2020-01-01}, journal = {Journal of Alloys and Compounds}, volume = {835}, abstract = {In the present paper, the results of combined theoretical and experimental investigation of small non-stoichiometric bromine-doped potassium clusters are reported. Potassium-bromide clusters were obtained by the Knudsen cell combined with surface ionization in the temperature range of 1000–1600 K, and selected by a magnetic sector mass spectrometer. Positive ions of KnBr (n = 3–6) and KnBrn-1 (n = 3–5) clusters were detected for the first time in one set measurement. In order to reveal the geometrical structure of each type of detected cluster, the randomized search algorithm was employed to survey the (Born-Oppenheimer) potential energy surface of both the neutral and cationic KnBr(0,1+) (n = 1–6) and KnBrn-1(0,1+) (n=3–5) clusters, followed by Density functional theory geometry optimizations, and many lowest-energy conformational isomers are presented. From the total electronic energies of clusters computed by the ab initio RCCSD(T)/ECP10MDF(K),cc-pVTZ-PP(Br) method at obtained equilibrium nuclear geometries, the following stability parameters of clusters were computed: their relative energies, the adiabatic and vertical ionization energies, binding energies per atom, and dissociation energies. Both experimental and theoretical results have shown that the title clusters belong to the group of “superalkali” clusters. © 2020 Elsevier B.V.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In the present paper, the results of combined theoretical and experimental investigation of small non-stoichiometric bromine-doped potassium clusters are reported. Potassium-bromide clusters were obtained by the Knudsen cell combined with surface ionization in the temperature range of 1000–1600 K, and selected by a magnetic sector mass spectrometer. Positive ions of KnBr (n = 3–6) and KnBrn-1 (n = 3–5) clusters were detected for the first time in one set measurement. In order to reveal the geometrical structure of each type of detected cluster, the randomized search algorithm was employed to survey the (Born-Oppenheimer) potential energy surface of both the neutral and cationic KnBr(0,1+) (n = 1–6) and KnBrn-1(0,1+) (n=3–5) clusters, followed by Density functional theory geometry optimizations, and many lowest-energy conformational isomers are presented. From the total electronic energies of clusters computed by the ab initio RCCSD(T)/ECP10MDF(K),cc-pVTZ-PP(Br) method at obtained equilibrium nuclear geometries, the following stability parameters of clusters were computed: their relative energies, the adiabatic and vertical ionization energies, binding energies per atom, and dissociation energies. Both experimental and theoretical results have shown that the title clusters belong to the group of “superalkali” clusters. © 2020 Elsevier B.V. |
Novčić, K A; Dobrota, A S; Petković, M; Johansson, B; Skorodumova, N V; Mentus, S V; Pašti, I A Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries – the impact of the computational scheme Journal Article Electrochimica Acta, 354 , 2020. @article{Novčić2020, title = {Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries – the impact of the computational scheme}, author = {K A Novčić and A S Dobrota and M Petković and B Johansson and N V Skorodumova and S V Mentus and I A Pašti}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087973660&doi=10.1016%2fj.electacta.2020.136735&partnerID=40&md5=3e5bdf0fec3b50f407572ac15428741c}, doi = {10.1016/j.electacta.2020.136735}, year = {2020}, date = {2020-01-01}, journal = {Electrochimica Acta}, volume = {354}, abstract = {Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding the reactions in M-O2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O2 and Na-O2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates. © 2020 |
Batalović, K; Radaković, J; Bundaleski, N; Rakočević, Z; Pašti, I; Skorodumova, N V; Rangel, C M Origin of photocatalytic activity enhancement in Pd/Pt-deposited anatase N-TiO2-experimental insights and DFT study of the (001) surface Journal Article Physical Chemistry Chemical Physics, 22 (33), pp. 18536-18547, 2020. @article{Batalović202018536, title = {Origin of photocatalytic activity enhancement in Pd/Pt-deposited anatase N-TiO2-experimental insights and DFT study of the (001) surface}, author = {K Batalović and J Radaković and N Bundaleski and Z Rakočević and I Pašti and N V Skorodumova and C M Rangel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090249769&doi=10.1039%2fd0cp03186k&partnerID=40&md5=9c831096bfaf9104a17eaf710530b8d7}, doi = {10.1039/d0cp03186k}, year = {2020}, date = {2020-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, number = {33}, pages = {18536-18547}, abstract = {In pursuit of the ideal photocatalyst, cheap and stable semiconductor TiO2 is considered to be a good choice if one is able to reduce its band gap and decrease the recombination rate of charge carriers. The approach that offers such improvements for energy conversion applications is the modification of TiO2 with nitrogen and noble metals. However, the origin of these improvements and possibilities for further design of single-atom catalysts are not always straightforward. To shed light on the atomic-scale picture, we modeled the nitrogen-doped (001) anatase TiO2 surface as a support for palladium and platinum single-atom deposition. The thermodynamics of various synthesis routes for Pd/Pt deposition and nitrogen doping is considered based on density functional theory (DFT)-calculated energies, highlighting the effect of nitrogen doping on metal dimer formation and metal-support interaction. XPS analysis of the valence band of the modified TiO2 nanocrystals, and the calculated charge transfer and electronic structure of single-atom catalysts supported on the (001) anatase TiO2 surface provide an insight into modifications occurring in the valence zone of TiO2 due to nitrogen doping and Pd/Pt deposition at the surface. DFT results also show that substitutional nitrogen doping significantly increases metal-support interaction, while interstitial nitrogen doping promotes only Pt-support interaction. © the Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In pursuit of the ideal photocatalyst, cheap and stable semiconductor TiO2 is considered to be a good choice if one is able to reduce its band gap and decrease the recombination rate of charge carriers. The approach that offers such improvements for energy conversion applications is the modification of TiO2 with nitrogen and noble metals. However, the origin of these improvements and possibilities for further design of single-atom catalysts are not always straightforward. To shed light on the atomic-scale picture, we modeled the nitrogen-doped (001) anatase TiO2 surface as a support for palladium and platinum single-atom deposition. The thermodynamics of various synthesis routes for Pd/Pt deposition and nitrogen doping is considered based on density functional theory (DFT)-calculated energies, highlighting the effect of nitrogen doping on metal dimer formation and metal-support interaction. XPS analysis of the valence band of the modified TiO2 nanocrystals, and the calculated charge transfer and electronic structure of single-atom catalysts supported on the (001) anatase TiO2 surface provide an insight into modifications occurring in the valence zone of TiO2 due to nitrogen doping and Pd/Pt deposition at the surface. DFT results also show that substitutional nitrogen doping significantly increases metal-support interaction, while interstitial nitrogen doping promotes only Pt-support interaction. © the Owner Societies. |
Rafajilović, M R; Radulović, K; Smiljanić, M M; Lazić, Z; Jakšić, Z; Stanisavljev, D; Radović, D V Micromachines, 11 (9), 2020. @article{Rafajilović2020, title = {Monolithically integrated diffused silicon two-zone heaters for silicon-pyrex glass microreactors for production of nanoparticles: Heat exchange aspects}, author = {M R Rafajilović and K Radulović and M M Smiljanić and Z Lazić and Z Jakšić and D Stanisavljev and D V Radović}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092367265&doi=10.3390%2fmi11090818&partnerID=40&md5=8a1eae9009a0f812f8e5ca6c4dcf77ee}, doi = {10.3390/mi11090818}, year = {2020}, date = {2020-01-01}, journal = {Micromachines}, volume = {11}, number = {9}, abstract = {We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters' operation and performance. Our experimental model reactor structure consisted of a silicon wafer anodically bonded to a Pyrex glass wafer with an isotropically etched serpentine microchannels network. We fabricated two separate spiral heaters with different temperatures, mutually thermally isolated by barrier apertures etched throughout the silicon wafer. The heaters were characterized by electric measurements and by infrared thermal vision. The obtained results show that our proposed procedure for the heater fabrication is robust, stable and controllable, with a decreased sensitivity to random variations of fabrication process parameters. Compared to metallic or polysilicon heaters typically integrated into microreactors, our approach offers improved control over heater characteristics through adjustment of the Boron doping level and profile. Our microreactor is intended to produce titanium dioxide nanoparticles, but it could be also used to fabricate nanoparticles in different materials as well, with various parameters and geometries. Our method can be generally applied to other high-temperature microsystems. © 2020 by the authors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present the design, simulation, fabrication and characterization of monolithically integrated high resistivity p-type boron-diffused silicon two-zone heaters in a model high temperature microreactor intended for nanoparticle fabrication. We used a finite element method for simulations of the heaters' operation and performance. Our experimental model reactor structure consisted of a silicon wafer anodically bonded to a Pyrex glass wafer with an isotropically etched serpentine microchannels network. We fabricated two separate spiral heaters with different temperatures, mutually thermally isolated by barrier apertures etched throughout the silicon wafer. The heaters were characterized by electric measurements and by infrared thermal vision. The obtained results show that our proposed procedure for the heater fabrication is robust, stable and controllable, with a decreased sensitivity to random variations of fabrication process parameters. Compared to metallic or polysilicon heaters typically integrated into microreactors, our approach offers improved control over heater characteristics through adjustment of the Boron doping level and profile. Our microreactor is intended to produce titanium dioxide nanoparticles, but it could be also used to fabricate nanoparticles in different materials as well, with various parameters and geometries. Our method can be generally applied to other high-temperature microsystems. © 2020 by the authors. |
Milenković, D A; Dimić, D S; Avdović, E H; Amić, A D; Marković, Dimitrić J M; Marković, Z S Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products Journal Article Chemical Engineering Journal, 395 , 2020. @article{Milenković2020b, title = {Advanced oxidation process of coumarins by hydroxyl radical: Towards the new mechanism leading to less toxic products}, author = {D A Milenković and D S Dimić and E H Avdović and A D Amić and J M Dimitrić Marković and Z S Marković}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083333113&doi=10.1016%2fj.cej.2020.124971&partnerID=40&md5=66e7cb80160ef8312eccd626299c8eb9}, doi = {10.1016/j.cej.2020.124971}, year = {2020}, date = {2020-01-01}, journal = {Chemical Engineering Journal}, volume = {395}, abstract = {The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020}, keywords = {}, pubstate = {published}, tppubtype = {article} } The excessive use of coumarins and their derivatives is becoming an ecological concern due to their toxicity towards different organisms. One of the possible ways of their removal is the advanced oxidation processes. The oxidative breakdown of 4-hydroxycoumarin and its two derivatives, induced by a very powerful oxidizer hydroxyl radical (HO•), was investigated experimentally and theoretically. The new mechanism, namely radical adduct formation followed by hydrogen atom abstraction (RAF-HAA), was proposed. The thermodynamic parameters and rate constants, calculated by the Transition State Theory for several active positions indicated a possible reaction in which less toxic products were obtained, as confirmed by the ecotoxicity assessment. The mechanism included the reaction with two HO• and the introduction of an additional OH group to the structure. These results were compared to the more common mechanism that includes HAA between the OH group of 4-hydroxycoumarin and HO•. Based on the Quantum Theory of Atoms in Molecules and Natural Bond Orbital theory the exo-coupled electron transfer (PCET) mechanism was pointed out as a dominant pathway. Radical addiction with another HO•, followed by keto-enol tautomerism, led to the formation of the stable final product, identical to one obtained in the RAF-HAA mechanism. The reaction rates for RAF-HAA were higher then those for pure HAA and reactions were more spontaneous, therefore leading to the conclusion that the newly proposed mechanism could be a dominant pathway for the aromatic molecules’ breakdown in the advanced oxidation processes. © 2020 |
Radinović, K; Milikić, J; Santos, D M F; Saccone, A; Negri, De S; Šljukić, B Electroanalytical sensing of trace amounts of As(III) in water resources by Gold–Rare Earth alloys Journal Article Journal of Electroanalytical Chemistry, 872 , 2020. @article{Radinović2020, title = {Electroanalytical sensing of trace amounts of As(III) in water resources by Gold–Rare Earth alloys}, author = {K Radinović and J Milikić and D M F Santos and A Saccone and S De Negri and B Šljukić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091109218&doi=10.1016%2fj.jelechem.2020.114232&partnerID=40&md5=4ed28570042454e62f246d7447a7413d}, doi = {10.1016/j.jelechem.2020.114232}, year = {2020}, date = {2020-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {872}, abstract = {Gold–Rare Earth (Au-RE}, keywords = {}, pubstate = {published}, tppubtype = {article} } Gold–Rare Earth (Au-RE |
Mladenović, D; Vujković, M; Mentus, S; Santos, D M F; Rocha, R P; Sequeira, C A C; Figueiredo, J L; Šljukić, B Carbon-supported mo2c for oxygen reduction reaction electrocatalysis Journal Article Nanomaterials, 10 (9), pp. 1-12, 2020. @article{Mladenović20201, title = {Carbon-supported mo2c for oxygen reduction reaction electrocatalysis}, author = {D Mladenović and M Vujković and S Mentus and D M F Santos and R P Rocha and C A C Sequeira and J L Figueiredo and B Šljukić}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090765590&doi=10.3390%2fnano10091805&partnerID=40&md5=a2dee5f292f3a717d6663dc3ccbbaabc}, doi = {10.3390/nano10091805}, year = {2020}, date = {2020-01-01}, journal = {Nanomaterials}, volume = {10}, number = {9}, pages = {1-12}, abstract = {Molybdenum carbide (Mo2C)-based electrocatalysts were prepared using two different carbon supports, commercial carbon nanotubes (CNTs) and synthesised carbon xerogel (CXG), to be studied from the point of view of both capacitive and electrocatalytic properties. Cation type (K+ or Na+) in the alkaline electrolyte solution did not affect the rate of formation of the electrical double layer at a low scan rate of 10 mV s−1 . Conversely, the different mobility of these cations through the electrolyte was found to be crucial for the rate of double-layer formation at higher scan rates. Molybdenum carbide supported on carbon xerogel (Mo2C/CXG) showed ca. 3 times higher double-layer capacity amounting to 75 mF cm−2 compared to molybdenum carbide supported on carbon nanotubes (Mo2C/CNT) with a value of 23 mF cm−2 due to having more than double the surface area size. The electrocatalytic properties of carbon-supported molybdenum carbides for the oxygen reduction reaction in alkaline media were evaluated using linear scan voltammetry with a rotating disk electrode. The studied materials demonstrated good electrocatalytic performance with Mo2C/CXG delivering higher current densities at more positive onset and half-wave potential. The number of electrons exchanged during oxygen reduction reaction (ORR) was calculated to be 3, suggesting a combination of four-and two-electron mechanism. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molybdenum carbide (Mo2C)-based electrocatalysts were prepared using two different carbon supports, commercial carbon nanotubes (CNTs) and synthesised carbon xerogel (CXG), to be studied from the point of view of both capacitive and electrocatalytic properties. Cation type (K+ or Na+) in the alkaline electrolyte solution did not affect the rate of formation of the electrical double layer at a low scan rate of 10 mV s−1 . Conversely, the different mobility of these cations through the electrolyte was found to be crucial for the rate of double-layer formation at higher scan rates. Molybdenum carbide supported on carbon xerogel (Mo2C/CXG) showed ca. 3 times higher double-layer capacity amounting to 75 mF cm−2 compared to molybdenum carbide supported on carbon nanotubes (Mo2C/CNT) with a value of 23 mF cm−2 due to having more than double the surface area size. The electrocatalytic properties of carbon-supported molybdenum carbides for the oxygen reduction reaction in alkaline media were evaluated using linear scan voltammetry with a rotating disk electrode. The studied materials demonstrated good electrocatalytic performance with Mo2C/CXG delivering higher current densities at more positive onset and half-wave potential. The number of electrons exchanged during oxygen reduction reaction (ORR) was calculated to be 3, suggesting a combination of four-and two-electron mechanism. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. |
Ohui, K; Stepanenko, I; Besleaga, I; Babak, M V; Stafi, R; Darvasiova, D; Giester, G; Pósa, V; Enyedy, E A; Vegh, D; Rapta, P; Ang, W H; Popović-Bijelić, A; Arion, V B Triapine derivatives act as copper delivery vehicles to induce deadly metal overload in cancer cells Journal Article Biomolecules, 10 (9), pp. 1-22, 2020. @article{Ohui20201, title = {Triapine derivatives act as copper delivery vehicles to induce deadly metal overload in cancer cells}, author = {K Ohui and I Stepanenko and I Besleaga and M V Babak and R Stafi and D Darvasiova and G Giester and V Pósa and E A Enyedy and D Vegh and P Rapta and W H Ang and A Popović-Bijelić and V B Arion}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85091139362&doi=10.3390%2fbiom10091336&partnerID=40&md5=2ee971d1b2998deddb50f70d2b528359}, doi = {10.3390/biom10091336}, year = {2020}, date = {2020-01-01}, journal = {Biomolecules}, volume = {10}, number = {9}, pages = {1-22}, abstract = {Thiosemicarbazones continue to attract the interest of researchers as potential anticancer drugs. For example, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone, or triapine, is the most well-known representative of this class of compounds that has entered multiple phase I and II clinical trials. Two new triapine derivatives HL1 and HL2 were prepared by condensation reactions of 2-pyridinamidrazone and S-methylisothiosemicarbazidium chloride with 3-N-(tert-butyloxycarbonyl) amino-pyridine-2-carboxaldehyde, followed by a Boc-deprotection procedure. Subsequent reaction of HL1 and HL2 with CuCl2·2H2 O in 1:1 molar ratio in methanol produced the complexes [CuII (HL1)Cl2 ]·H2 O (1·H2 O) and [CuII (HL2)Cl2 ] (2). The reaction of HL2 with Fe(NO3)3·9H2 O in 2:1 molar ratio in the presence of triethylamine afforded the complex [FeIII (L2)2 ]NO3·0.75H2 O (3·0.75H2 O), in which the isothiosemicarbazone acts as a tridentate monoanionic ligand. The crystal structures of HL1, HL2 and metal complexes 1 and 2 were determined by single crystal X-ray diffraction. The UV-Vis and EPR spectroelectrochemical measurements revealed that complexes 1 and 2 underwent irreversible reduction of Cu(II) with subsequent ligand release, while 3 showed an almost reversible electrochemical reduction in dimethyl sulfoxide (DMSO). Aqueous solution behaviour of HL1 and 1, as well as of HL2 and its complex 2, was monitored as well. Complexes 1−3 were tested against ovarian carcinoma cells, as well as noncancerous embryonic kidney cells, in comparison to respective free ligands, triapine and cisplatin. While the free ligands HL1 and HL2 were devoid of antiproliferative activity, their respective metal complexes showed remarkable antiproliferative activity in a micromolar concentration range. The activity was not related to the inhibition of ribonucleotide reductase (RNR) R2 protein, but rather to cancer cell homeostasis disturbance—leading to the disruption of cancer cell signalling. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Thiosemicarbazones continue to attract the interest of researchers as potential anticancer drugs. For example, 3-aminopyridine-2-carboxaldehyde thiosemicarbazone, or triapine, is the most well-known representative of this class of compounds that has entered multiple phase I and II clinical trials. Two new triapine derivatives HL1 and HL2 were prepared by condensation reactions of 2-pyridinamidrazone and S-methylisothiosemicarbazidium chloride with 3-N-(tert-butyloxycarbonyl) amino-pyridine-2-carboxaldehyde, followed by a Boc-deprotection procedure. Subsequent reaction of HL1 and HL2 with CuCl2·2H2 O in 1:1 molar ratio in methanol produced the complexes [CuII (HL1)Cl2 ]·H2 O (1·H2 O) and [CuII (HL2)Cl2 ] (2). The reaction of HL2 with Fe(NO3)3·9H2 O in 2:1 molar ratio in the presence of triethylamine afforded the complex [FeIII (L2)2 ]NO3·0.75H2 O (3·0.75H2 O), in which the isothiosemicarbazone acts as a tridentate monoanionic ligand. The crystal structures of HL1, HL2 and metal complexes 1 and 2 were determined by single crystal X-ray diffraction. The UV-Vis and EPR spectroelectrochemical measurements revealed that complexes 1 and 2 underwent irreversible reduction of Cu(II) with subsequent ligand release, while 3 showed an almost reversible electrochemical reduction in dimethyl sulfoxide (DMSO). Aqueous solution behaviour of HL1 and 1, as well as of HL2 and its complex 2, was monitored as well. Complexes 1−3 were tested against ovarian carcinoma cells, as well as noncancerous embryonic kidney cells, in comparison to respective free ligands, triapine and cisplatin. While the free ligands HL1 and HL2 were devoid of antiproliferative activity, their respective metal complexes showed remarkable antiproliferative activity in a micromolar concentration range. The activity was not related to the inhibition of ribonucleotide reductase (RNR) R2 protein, but rather to cancer cell homeostasis disturbance—leading to the disruption of cancer cell signalling. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. |
Jerosimić, S; Milovanović, M; Koprivica, D; Wester, R; Gianturco, F A Structural properties of possible interstellar valence anions of the series HC: NN-(n = 3, 5, 7, 9) Journal Article Physical Chemistry Chemical Physics, 22 (30), pp. 17263-17274, 2020. @article{Jerosimić202017263, title = {Structural properties of possible interstellar valence anions of the series HC: NN-(n = 3, 5, 7, 9)}, author = {S Jerosimić and M Milovanović and D Koprivica and R Wester and F A Gianturco}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089205494&doi=10.1039%2fd0cp02666b&partnerID=40&md5=e37b048b5f0762a84e6b871b1cf219d5}, doi = {10.1039/d0cp02666b}, year = {2020}, date = {2020-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {22}, number = {30}, pages = {17263-17274}, abstract = {In this contribution we investigate the structural properties of stable anions of small carbon clusters, with one nitrogen and one hydrogen atoms attached to the C-cluster, to surmise their possible existence in the Interstellar Medium (ISM). Many possible configurational (geometrical) isomers with positive vertical electron detachment values are presented, and arranged according to their relative energy. Specific attention is paid to the structures of the lowest-energy valence isomers, the chain-structures of HC7N- and HC9N- anions with quasilinear and linear geometry, respectively. They exhibit relatively large permanent dipole moments (2.697 and 5.034 Debye) and adiabatic electron affinities (AEAs) of 1.13 and 1.35 eV. Isomers of the HNCn- family and many branched structures are possible stable species viable for detection in the ISM. © 2020 the Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this contribution we investigate the structural properties of stable anions of small carbon clusters, with one nitrogen and one hydrogen atoms attached to the C-cluster, to surmise their possible existence in the Interstellar Medium (ISM). Many possible configurational (geometrical) isomers with positive vertical electron detachment values are presented, and arranged according to their relative energy. Specific attention is paid to the structures of the lowest-energy valence isomers, the chain-structures of HC7N- and HC9N- anions with quasilinear and linear geometry, respectively. They exhibit relatively large permanent dipole moments (2.697 and 5.034 Debye) and adiabatic electron affinities (AEAs) of 1.13 and 1.35 eV. Isomers of the HNCn- family and many branched structures are possible stable species viable for detection in the ISM. © 2020 the Owner Societies. |
