Unusual coordination of the superoxide ion O2 ? with molecules of halogenated hydrocarbons

Talzi, E. P.; Stepanov, Alexander G.; Babenko, V. P.; Nekipelov, V. M.; Zamaraev, K. I.

doi:10.1007/bf00748181

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…[20,28] As g ʈ = 2.275 is higher than the typical values observed for copper() complexes with an N 2 O 2 coordinating sphere and similar to those observed by Talzi et al, [30] we propose that the major Cu species immobilised in [Cu(acac) 2 ]AMPTSi/HMS_B have an NO 3 coordinating sphere as shown in Scheme 1 (other species, for example, with an N 2 O 2 coordination sphere and present in low quantities, cannot be unambiguously excluded because of the solid-state broadening effects in the EPR spectra). Although the spectrum was taken at low temperature, the bandwidths of the signals are still large to detect the nitrogen superhyperfine splittings (typically 14-25 G), due to the interaction between the copper unpaired spin and the nitrogen nuclear spin (I = 1), hence hindering the direct confirmation of nitrogen atoms coordinated to the copper() centre in the equatorial plane.…”

Section: Anchoring Of Copper(ii) Acetylacetonate Onto the Aminefunctisupporting

confidence: 87%

“…An NO 3 coordination sphere would give rise to intermediate g values, with some overlap with the intervals given above, but confirmation with experimental data is quite difficult due not only to the failure of the preparation the free counterpart of the anchored complex (all synthetic attempts resulted in oils which we were unable to fully characterise), but also to the almost nonexistent EPR data for compounds with these coordinating atoms: only Murphy et al reported a silica-anchored [Cu(salicylaldimine)] species with an NO 3 coordinating sphere, which showed a g ʈ = 2.29 [20] and Talzi et al reported Cu II complexes with an equatorial NO 3 coordination sphere with g ʈ = 2.27-2.28. [30] Nevertheless, some insights into the coordination sphere of the anchored complex can be gathered indirectly by comparison with g and A values of the parent copper complex and those with mixed NO 3 coordination spheres shown in Table 3.…”

Section: Anchoring Of Copper(ii) Acetylacetonate Onto the Aminefunctimentioning

confidence: 99%

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Amine‐Functionalised Hexagonal Mesoporous Silica as Support for Copper(II) Acetylacetonate Catalyst

et al. 2006

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Copper(II) acetylacetonate was anchored onto a hexagonal mesoporous silica (HMS) material using a two-step procedure: (i) functionalisation of the surface hydroxy groups with (3-aminopropyl)triethoxysilane (AMPTSi) and then (ii) anchoring of the copper(II) complex through Schiff condensation with free amine groups, using two different metal complex loadings. Upon the first step, nitrogen elemental analysis, XPS and DRIFT showed the presence of amine groups on the surface of the HMS material, and porosimetry indicated that the structure of the mesoporous material remained unchanged, although a slight decrease in surface area was observed. Atomic absorption, XPS and DRIFT showed that copper(II) acetylacetonate was anchored onto the amine-functionalised HMS by Schiff condensation between the free amine groups and the carbonyl groups of the copper(II) com-

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Section: Anchoring Of Copper(ii) Acetylacetonate Onto the Aminefunctisupporting

confidence: 87%

Section: Anchoring Of Copper(ii) Acetylacetonate Onto the Aminefunctimentioning

confidence: 99%

Amine‐Functionalised Hexagonal Mesoporous Silica as Support for Copper(II) Acetylacetonate Catalyst

et al. 2006

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“…These are mainly square planar complexes sometimes with a weak coordination at the fifth position. Talzi et al [26] also reported copper(II) complexes with N 2 O 2 ligand geometry to show g k values of 2.27-2.28. Spectroscopic studies for Cu-S-SBA-15, therefore, clearly indicate that copper(II) complex formed in SBA-15 matrix is a square planar one as shown in Scheme 1A.…”

Section: Structural Integrity Analysismentioning

confidence: 90%

A novel copper(II) complex bearing salicylaldimine immobilized on SBA-15 and its catalytic performances in styrene oxidation by hydrogen peroxide

Yang

Hao

Qiu

et al. 2010

Reac Kinet Mech Cat

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Salicylaldimine functionalized SBA-15 hybrid mesoporous material was synthesized by post-grafting of salicylaldehyde modified 3-aminopropyltriethoxysilane and followed by introducing Cu(II) ions into the hybrid material via a ligand exchange reaction. The prepared catalyst was characterized by means of XRD, N 2 adsorption/desorption, SEM, FT-IR, UV-vis spectroscopy, EPR and XPS techniques as well as ICP-AES and elemental analysis measurements. The solid catalyst was evaluated in the oxidation of styrene with H 2 O 2 as the oxidant under mild conditions, and the reaction parameters (the molar ratio of styrene/H 2 O 2 , amount of catalyst, temperatures, solvents, alkaline additive) were investigated and optimized for the oxidation of styrene. The optimal conversion (77.1%) and yield of styrene oxide (60.0%) were obtained at 80°C using CH 3 CN as the solvent under basic conditions. Moreover, the covalently anchored Cu(II) salicylaldimine complex showed good recoverability and high stability against leaching of active copper(II) species.

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“…7,11 Organic radicals with g-factors 42.01 have been observed previously in the presence of halogenated solvents. 31 Experiments were prepared using dichloromethane, so to rule out the possibility of trapped solvent interacting with the radicals, an experiment was performed (results not shown) using benzene as a solvent, thus removing any chance of halogens entering the system, and no differences were found between experiments with different solvents. Therefore the radical with a g-factor of 2.0116 is likely also an oxygen centred radical on highly oxidized PAC (Table 2).…”

Section: Pccp Papermentioning

confidence: 99%

Formation of environmentally persistent free radicals from the heterogeneous reaction of ozone and polycyclic aromatic compounds

Borrowman

Zhou

Burrow

et al. 2016

Phys. Chem. Chem. Phys.

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In the 1980s long-lived radical species were identified in cigarette tar. Since then, environmentally persistent free radicals (EPFRs) have been observed in ambient particulate matter, and have been generated in particulate matter generated from internal combustion engines. For the first time, we measure in situ the formation and decay of EPFRs through the heterogeneous reaction of ozone and several polycyclic aromatic compounds (PAC). Solid anthracene (ANT), pyrene (PY), benzo[a]pyrene (BAP), benzo[ghi]perylene (BGHIP), 1,4-naphthoquinone (1,4NQ), and 9,10-anthraquinone (AQ) were reacted with gas-phase ozone in a flow system placed in the active cavity of an electron paramagnetic resonance (EPR) spectrometer, and the formation of radicals was measured on the timescale of tens of minutes at ambient levels of ozone down to 30 ppb. For most substrates the net radical production is initially rapid, slows at intermediate times, and is followed by a slow decay. For oxidized solid BAP, radical signal persists for many days in the absence of ozone. To evaluate the effect of substrate phase, the solid PAHs were also dissolved in squalane, an organic oil inert to ozone, which yielded a much higher maximum radical concentration and faster radical decay when exposed to ozone. With higher mobility, reactants were apparently able to more easily diffuse and react with each other, yielding the higher radical concentrations. The EPR spectra exhibit three radicals types, two of which have been assigned to semiquinone species and one to a PAH-derived, carbon-centered radical. Although our system uses levels of PAC not typically found in the environment it is worth noting that the amounts of radical formed, on the order of 10(18) radicals per g, are comparable to those observed in ambient particulate matter.

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Unusual coordination of the superoxide ion O2 ? with molecules of halogenated hydrocarbons

Cited by 4 publications

References 13 publications

Amine‐Functionalised Hexagonal Mesoporous Silica as Support for Copper(II) Acetylacetonate Catalyst

Amine‐Functionalised Hexagonal Mesoporous Silica as Support for Copper(II) Acetylacetonate Catalyst

A novel copper(II) complex bearing salicylaldimine immobilized on SBA-15 and its catalytic performances in styrene oxidation by hydrogen peroxide

Formation of environmentally persistent free radicals from the heterogeneous reaction of ozone and polycyclic aromatic compounds

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