Mechanistic information on metalation and transmetalation of chlorophylls

2009
journal article
article
12
dc.abstract.enChlorophyll a and pheophytin a have been treated with various metal salts in solution. As a result, metallo derivatives of photosynthetic pigments were formed, or the chlorine ring was oxidized. These studies showed that both effects can be caused by $Cu^{II}$ ions depending on the redox potential of its complexes formed in specific media. In this report the results of studies on metal insertion and exchange reactions are presented. According to the common use of the "acetate method" in the synthesis of metallotetrapyrroles, and the fact that acetates coordinated to $Cu^{II}$ ions protect chlorophylls from oxidative degradation, $Cu^{II}$ acetate monohydrate was selected as main reagent. The metalation and transmetalation processes were investigated with spectroscopic (UV/Vis absorption and emission) and kinetic (conventional and high-pressure) techniques. It turned out that differences in solvent properties can significantly affect not only the rates (metalation), but also the course (transmetalation) of the reaction. The most pronounced effect was found for the transmetalation reaction in acetonitrile, which was terminated at the very initial stage. As shown elsewhere, some special agents/factors, such as excess of acetate, are required to facilitate the dissociation of $Mg^{2+}$ and to push the reaction forward towards formation of the $Cu^{II}$ derivative of chlorophyll. The mechanisms of two other reactions are proposed on the basis of the determined activation parameters, which correspond to the general mechanisms for metalation and transmetalation of tetrapyrroles with sitting-atop and bimetallic intermediates, respectively. The bimetallic complex of chlorophyll in methanol is probably the most stable complex of this type observed ever. It confirms that spontaneous exchange of $Mg^{2+}$ by $Cu^{II}$ occurring in plants must result from specific conditions and/or involve contribution from other components of the photosystem.pl
dc.affiliationWydział Chemii : Zakład Chemii Nieorganicznejpl
dc.affiliationWydział Biochemii, Biofizyki i Biotechnologii : Zakład Fizjologii i Biochemii Roślinpl
dc.contributor.authorOrzeł, Łukasz - 131198 pl
dc.contributor.authorvan Eldik, Rudi - 239234 pl
dc.contributor.authorFiedor, Leszek - 127902 pl
dc.contributor.authorStochel, Grażyna - 132108 pl
dc.date.accessioned2015-09-16T12:33:26Z
dc.date.available2015-09-16T12:33:26Z
dc.date.issued2009pl
dc.description.admin[AU] van Eldik, Rudi [SAP14007947]pl
dc.description.number16pl
dc.description.physical2393-2406pl
dc.description.volume2009pl
dc.identifier.doi10.1002/ejic.200800662pl
dc.identifier.eissn1099-0682pl
dc.identifier.issn1434-1948pl
dc.identifier.urihttp://ruj.uj.edu.pl/xmlui/handle/item/15696
dc.languageengpl
dc.language.containerengpl
dc.rightsDodaję tylko opis bibliograficzny*
dc.rights.licencebez licencji
dc.rights.uri*
dc.subtypeArticlepl
dc.titleMechanistic information on $Cu^{II}$ metalation and transmetalation of chlorophyllspl
dc.title.journalEuropean Journal of Inorganic Chemistrypl
dc.typeJournalArticlepl
dspace.entity.typePublication
dc.abstract.enpl
Chlorophyll a and pheophytin a have been treated with various metal salts in solution. As a result, metallo derivatives of photosynthetic pigments were formed, or the chlorine ring was oxidized. These studies showed that both effects can be caused by $Cu^{II}$ ions depending on the redox potential of its complexes formed in specific media. In this report the results of studies on metal insertion and exchange reactions are presented. According to the common use of the "acetate method" in the synthesis of metallotetrapyrroles, and the fact that acetates coordinated to $Cu^{II}$ ions protect chlorophylls from oxidative degradation, $Cu^{II}$ acetate monohydrate was selected as main reagent. The metalation and transmetalation processes were investigated with spectroscopic (UV/Vis absorption and emission) and kinetic (conventional and high-pressure) techniques. It turned out that differences in solvent properties can significantly affect not only the rates (metalation), but also the course (transmetalation) of the reaction. The most pronounced effect was found for the transmetalation reaction in acetonitrile, which was terminated at the very initial stage. As shown elsewhere, some special agents/factors, such as excess of acetate, are required to facilitate the dissociation of $Mg^{2+}$ and to push the reaction forward towards formation of the $Cu^{II}$ derivative of chlorophyll. The mechanisms of two other reactions are proposed on the basis of the determined activation parameters, which correspond to the general mechanisms for metalation and transmetalation of tetrapyrroles with sitting-atop and bimetallic intermediates, respectively. The bimetallic complex of chlorophyll in methanol is probably the most stable complex of this type observed ever. It confirms that spontaneous exchange of $Mg^{2+}$ by $Cu^{II}$ occurring in plants must result from specific conditions and/or involve contribution from other components of the photosystem.
dc.affiliationpl
Wydział Chemii : Zakład Chemii Nieorganicznej
dc.affiliationpl
Wydział Biochemii, Biofizyki i Biotechnologii : Zakład Fizjologii i Biochemii Roślin
dc.contributor.authorpl
Orzeł, Łukasz - 131198
dc.contributor.authorpl
van Eldik, Rudi - 239234
dc.contributor.authorpl
Fiedor, Leszek - 127902
dc.contributor.authorpl
Stochel, Grażyna - 132108
dc.date.accessioned
2015-09-16T12:33:26Z
dc.date.available
2015-09-16T12:33:26Z
dc.date.issuedpl
2009
dc.description.adminpl
[AU] van Eldik, Rudi [SAP14007947]
dc.description.numberpl
16
dc.description.physicalpl
2393-2406
dc.description.volumepl
2009
dc.identifier.doipl
10.1002/ejic.200800662
dc.identifier.eissnpl
1099-0682
dc.identifier.issnpl
1434-1948
dc.identifier.uri
http://ruj.uj.edu.pl/xmlui/handle/item/15696
dc.languagepl
eng
dc.language.containerpl
eng
dc.rights*
Dodaję tylko opis bibliograficzny
dc.rights.licence
bez licencji
dc.rights.uri*
dc.subtypepl
Article
dc.titlepl
Mechanistic information on $Cu^{II}$ metalation and transmetalation of chlorophylls
dc.title.journalpl
European Journal of Inorganic Chemistry
dc.typepl
JournalArticle
dspace.entity.type
Publication

* The migration of download and view statistics prior to the date of April 8, 2024 is in progress.

Views
27
Views per month
Views per city
Ashburn
6
Krakow
5
Dublin
2
Katowice
2
Wroclaw
2
Des Moines
1

No access

No Thumbnail Available