Schiff bases containing metal complexes anchored on aerosil as catalysts of low-temperature ozone decomposition

Effect of the structure of copper(II) complexes, adsorbed on the surface of SiO2, on their catalytic activity in ozone decomposition

“…For copper(II) complexes with the ligands L1-L3, a weak band appears for a d-d transition at 14800 cm -1 , and with the ligand L4 weak bands appear at 14000 cm -1 and 12200 cm -1 . The analysis in [6] of the parameters of the EPR spectra, taking into account the data in [10], for copper(II) complexes with ligands L1-L4 and also the diffusion reflection results indicate formation on the aerosil surface of complexes with identical geometry, and specifically pseudotetrahedral bis-ligand complexes of CuN 2 O 2 , which is not inconsistent with the results of [5,6,11]. The band at 18000 cm -1 for the complex with L4 may be evidence for the presence of copper(II) complexes with magnetic exchange interactions, as is apparent in the broadening of the EPR signal.…”

“…If there are no steric hindrances in the ligands, the azomethine and deprotonated OH group form pseudotetrahedral bis-ligand complexes of copper(II) according to the same mechanism [5,6]. In the case when steric hindrances are present (L5), a coordination-unsaturated pseudooctahedral complex is formed.…”

“…Such complexes have demonstrated higher catalytic activity and stability compared with their liquid-phase analogs. A substantial change in catalytic properties in ozone decomposition has been exhibited by chloride complexes of copper(II) anchored on SiO 2 by the impregnation method [4], and also by copper(II) complexes with Schiff's bases immobilized on aerosil (propyl salicylaldimine, 5-bromo propyl salicylaldimine, and 2-hydroxynaphthalene propyl aldimine) [5,6]. In contrast to the previous examples, the indicated copper(II) complexes do not catalyze decomposition of ozone in the liquid phase [7], so information about the effect of the anchoring method, the composition, and the structure of copper(II) complexes on the ozone decomposition kinetics is needed to predict their catalytic activity in redox reactions.…”

Mono- and Bimetallic Complexes of Mn(II), Co(II), Cu(II), and Zn(II) with Schiff Bases Immobilized on Nanosilica as Catalysts in Ozone Decomposition Reaction

“…As shown in the previous papers [1,[14][15][16][17], the firstorder reaction rate constants can be calculated in many cases from the initial portions of kinetic curves of ozone decomposition. Their values are invariable at the beginning of the reaction but change at the half-conversion time confirming the radical chain mechanism of the reaction.…”

“…The results of analyzing kinetic (τ 1/2 , k 1/2 ) and stoichiometric (Q exp , n) parameters for all nanocomposites under study are summarized in Table 3. Based on the classic conceptions concerning the mechanism of ozone decomposition [2][3][4] and our studies of kinetics of ozone decomposition by 3d metal complexes with Schiff bases immobilized on nanosilica [1,[14][15][16][17], it can be deduced that metal ions taking part in the chain propagation reaction increase the time of ozone halfconversion attainment (k 1/2 decreases) and the amount of ozone entering the reaction over the whole period of its proceeding (Q exp ). In this case, the higher the τ 1/2 and Q exp the more actively complex decomposes ozone.…”