Charge effects on the photochemistry of the Co(EDTA)-·I- system in the presence of polyammonium macrocyclic receptors

Fernando Pina, A. Jorge Parola, Andrea Bencini, Mauro Micheloni, M. Francesca Manfrin, Luca Moggi

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Abstract

The effects of polyammonium macrocycles on the spectroscopic and photochemical properties of the Co(EDTA)-·I- ion-pair have been investigated. The addition of a macrocycle to aqueous solutions containing Co(EDTA)- and I- causes an increase of the absorbance in the region of the ion-pair charge-transfer band, as well as an increase of the quantum yield for the intramolecular photooxidation reduction of the ion-pair. Both these effects are mainly, if not only, due to an increase of the association constant between Co(EDTA)- and I-, caused by the positive charge of the macrocycle bound to the complex. On the contrary no change was observed on the intrinsic photoreactivity of the excited ion-pair. This last result is discussed in comparison with the effects already observed on the ligand photodissociation of MC excited states of Co(III) cyanide complexes.

Original languageEnglish
Pages (from-to)139-143
Number of pages5
JournalInorganica Chimica Acta
Volume195
Issue number2
DOIs
Publication statusPublished - 15 May 1992

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