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Observations on the mechanisms of the thermal and photoinduced oxidation of D-mannitol and fucoidan by transition metal complexes and inorganic radicals
The mechanism of the D-mannitol and fucoidan oxidation by *OH, peroxyl radicals, PRX* = , HOCH 2 , and CH 2 ( ) , inorganic radicals, , , and [Ni III (Me 6 -[14]aneN 4 )H 2 O] 3+ was investigated by pulse radiolysis. Relative to the diffusion-controlled reaction of the *OH radical, the reactions of...
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| Published in: | Journal of coordination chemistry 2011-02, Vol.64 (3), p.377-389 |
|---|---|
| Main Authors: | , , , |
| Format: | Article |
| Language: | English |
| Subjects: | |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | The mechanism of the D-mannitol and fucoidan oxidation by *OH, peroxyl radicals, PRX* =
, HOCH
2
, and CH
2
(
)
, inorganic radicals,
,
, and [Ni
III
(Me
6
-[14]aneN
4
)H
2
O]
3+
was investigated by pulse radiolysis. Relative to the diffusion-controlled reaction of the *OH radical, the reactions of PRX*,
, and
are slow, with a 10
5
-10
6
(mol L
−1
)
−1
s
−1
order of magnitude. The formation of saccharide-Ni(III) complexes also accounts for oxidation of the D-mannitol and fucoidan by [Ni
III
(Me
6
-[14]aneN
4
)H
2
O]
3+
. A rate constant k = 2.2 × 10
7
(mol L
−1
)
−1
s
−1
was estimated for the complexation of [Ni
III
(Me
6
-[14]aneN
4
)H
2
O]
3+
by D-mannitol. In addition, both carbohydrates accelerate the decay of the Ni(III) complex which occurs with half life t
1/2
∼ 10
2
ms. Consistent with the formation of fucoidan-Cu
2+
complexes, the flash irradiations of these complexes at 351 nm produces transient spectra assigned to
(n = 2, 3) species. The non-linear dependence of the product concentration on the flash intensity shows that formation of the species is a biphotonic process. |
|---|---|
| ISSN: | 0095-8972 1029-0389 |
| DOI: | 10.1080/00958972.2010.544724 |