Abstract:We describe the composition, structure, and catalytic activity in the reaction of ozone decomposition for copper(II) complexes with acido ligands and immobilized Schiff's bases (propyl benzaldimine derivatives) that are anchored on silica (silica gel, aerosil). We demonstrate methods for controlling their catalytic activity.Anchoring metal complexes on the surface of various supports by even very simple methods (impregnation, ion-exchange adsorption) leads to significant changes in their reactivity and catalyt… Show more
“…Furthermore, in some cases, additional bands appear. Similar changes were observed in the spectra of complexes and (L = L1–L6) [ 29 , 30 ].…”
Section: Resultssupporting
confidence: 74%
“…A similar example is the synthesis of Mn(II)(salen) complexes on porous amino silica gel (Si-NH 2 ) [ 17 ]. A comparison of the spectral data for similar Cu(II) and Co(II) [ 29 , 30 ] complexes and complexes permits to conclude that, for manganese(II), polyhedron N 2 O 2 also realizes in the ligand field of L1–L5 (Scheme 1 ). Scheme 1 Structure of the manganese(II) complexes with ligands L1-L5 …”
Section: Resultsmentioning
confidence: 97%
“…Analysis of data obtained as a result of the study of catalytic properties of 3d metal complexes with Schiff bases in the oxidation of organic compounds [ 15 , 17 , 18 , 20 – 22 , 24 , 26 – 28 ] and decomposition of ozone [ 29 , 30 ] leads to the conclusion that the catalytic activity of the immobilized metal complexes in redox reactions can be controlled by the following: (i) optimization of the structural characteristics of the carrier and the method of synthesis for obtaining the homogeneous structure and composition of immobilized complexes, (ii) changes in the geometric configuration of an immobilized complex, and (iii) redistribution of the electron density at the central atom and the ligand leading to a significant change in redox potential of M n+1 /M n+ pair and, hence, to the reactivity and catalytic activity of the complexes.…”
In this article, we submit the description of synthesis and identification of manganese(II) complexes with pyrogenic nanosilica-immobilized (dav = 10 nm; Ssp = 290 m2/g) hydroxyaldimine ligands : salicilaldiminopropyl (L1); 5-bromosalicilaldiminopropyl (L2); 2-hydroxynaphtaldiminopropyl (L3); 2-hydroxy-3-methoxybenzaldiminopropyl (L4); 2-hydroxy-3,5-dichloroacetophenoniminopropyl (L5); and 4-hydroxy-3-methoxybenzaldiminopropyl (L6). The ligands and complexes were characterized by UV-VIS and IR spectrometry. Nanocomposites consisting of complexes showed a high catalytic activity in low-temperature ozone decomposition in the range of concentrations between 2.1 × 10−6 and 8.4 × 10−6 mol/l. The number of catalytic cycles increased for isostructural pseudotetrahedral complexes (L1–L5) in the following order: Mn(L3)2 >> Mn(L4)2 > Mn(L1)2 > Mn(L2)2 > Mn(L5)2. In the case of pseudooctahedral complexes with L6, the change of coordination polyhedral does not influence the kinetics and stoichiometric parameters of the reaction.
“…Furthermore, in some cases, additional bands appear. Similar changes were observed in the spectra of complexes and (L = L1–L6) [ 29 , 30 ].…”
Section: Resultssupporting
confidence: 74%
“…A similar example is the synthesis of Mn(II)(salen) complexes on porous amino silica gel (Si-NH 2 ) [ 17 ]. A comparison of the spectral data for similar Cu(II) and Co(II) [ 29 , 30 ] complexes and complexes permits to conclude that, for manganese(II), polyhedron N 2 O 2 also realizes in the ligand field of L1–L5 (Scheme 1 ). Scheme 1 Structure of the manganese(II) complexes with ligands L1-L5 …”
Section: Resultsmentioning
confidence: 97%
“…Analysis of data obtained as a result of the study of catalytic properties of 3d metal complexes with Schiff bases in the oxidation of organic compounds [ 15 , 17 , 18 , 20 – 22 , 24 , 26 – 28 ] and decomposition of ozone [ 29 , 30 ] leads to the conclusion that the catalytic activity of the immobilized metal complexes in redox reactions can be controlled by the following: (i) optimization of the structural characteristics of the carrier and the method of synthesis for obtaining the homogeneous structure and composition of immobilized complexes, (ii) changes in the geometric configuration of an immobilized complex, and (iii) redistribution of the electron density at the central atom and the ligand leading to a significant change in redox potential of M n+1 /M n+ pair and, hence, to the reactivity and catalytic activity of the complexes.…”
In this article, we submit the description of synthesis and identification of manganese(II) complexes with pyrogenic nanosilica-immobilized (dav = 10 nm; Ssp = 290 m2/g) hydroxyaldimine ligands : salicilaldiminopropyl (L1); 5-bromosalicilaldiminopropyl (L2); 2-hydroxynaphtaldiminopropyl (L3); 2-hydroxy-3-methoxybenzaldiminopropyl (L4); 2-hydroxy-3,5-dichloroacetophenoniminopropyl (L5); and 4-hydroxy-3-methoxybenzaldiminopropyl (L6). The ligands and complexes were characterized by UV-VIS and IR spectrometry. Nanocomposites consisting of complexes showed a high catalytic activity in low-temperature ozone decomposition in the range of concentrations between 2.1 × 10−6 and 8.4 × 10−6 mol/l. The number of catalytic cycles increased for isostructural pseudotetrahedral complexes (L1–L5) in the following order: Mn(L3)2 >> Mn(L4)2 > Mn(L1)2 > Mn(L2)2 > Mn(L5)2. In the case of pseudooctahedral complexes with L6, the change of coordination polyhedral does not influence the kinetics and stoichiometric parameters of the reaction.
“…5 mm) activated by concentrated hydrochloric acid. Ozone trapping is based on the catalytic activity of Cu(II) compounds, in particular, CuCl 2 formed in the reaction with HCl from CuO deposited on the copper tube walls (Rakitskaya et al 2006;Spasova et al 2007). In our setup, ambient ozone concentrations were reduced from the level of 25-50 nmol mol -1 to ca.…”
Section: Study Site and Foliage Samplingmentioning
Changes in isoprene emission (Φ(isoprene)), and foliage photosynthetic (A) rates, isoprene precursor dimethylallyldiphosphate (DMADP), and nitrogen and carbon contents were studied from late summer to intensive leaf fall in Populus tremula to gain insight into the emission controls by temperature and endogenous, senescence-induced, modifications. Methanol emissions, characterizing degradation of cell wall pectins, were also measured. A rapid reduction in Φ(isoprene) and A of 60-70% of the initial value was observed in response to a rapid reduction of ambient temperature by ca. 15°C (cold stress). Later phases of senescence were associated with further reductions in Φ(isoprene) and A, with simultaneous major decrease in nitrogen content. However, during episodes of temperature increase, A and in particular, Φ(isoprene) partly recovered. Variation in Φ(isoprene) during senescence was correlated with average temperature of preceding days, with the highest degree of explained variance observed with average temperature of 6 days. Throughout the study, methanol emissions were small, but a large burst of methanol emission was associated with leaf yellowing and abscission. Overall, these data demonstrate that the capacity for isoprene emission can adjust to environmental conditions in senescing leaves as well, but the responsiveness is low compared with mid-season and is also affected by stress.
“…Concerning ozone, many examples of catalysts, which consist of two or more metals in different forms are mostly shown in patents [10]. Among the bimetallic complex catalysts only the catalysts with composition PdCl 2 -CuCl 2 (or NiCl 2 )/Al 2 O 3 are known [11].…”
Abstract.1 The results of the study of catalytic activity of nanocomposites containing mono-and bimetaliic manganese(II), cobalt(II), copper(II), and zinc(II) complexes with Schiff bases [(salicyl-aldiminopropyl (L1) and 2-hydroxy-4-methoxybenzophenoniminopropyl (L2)] immobilized on silica in the reaction of ozone decomposition are presented. The catalytic activity dependence on a nature of complexing metal ions and ligands has been determined.
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