Photochemistry of Anthracene-Appended Cobalt(iii) Cyclam Complexes

Simon Boyd; Kenneth P. Ghiggino; W. David McFadyen

doi:10.1071/CH08189

RESEARCH ARTICLE

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Photochemistry of Anthracene-Appended Cobalt(iii) Cyclam Complexes

Simon Boyd ^A , Kenneth P. Ghiggino ^A ^B and W. David McFadyen ^A

+ Author Affiliations

- Author Affiliations

^A School of Chemistry, University of Melbourne, Vic. 3010, Australia.

^B Corresponding author. Email: ghiggino@unimelb.edu.au

Australian Journal of Chemistry 61(8) 585-591 https://doi.org/10.1071/CH08189
Submitted: 4 May 2008 Accepted: 12 June 2008 Published: 15 August 2008

Abstract

The photochemistry of two anthracene-appended cobalt(iii) cyclam complexes is explored with a view to demonstrate a photoactivated ligand release process. The ligand exchange processes that occur in the complexes cis-[CoL(NO₂)(ONO)]⁺ and trans-[CoL(NO₂)(ONO)]⁺ in which L = 6-(anthracen-9-ylmethyl)-1,4,8,11-tetraazacyclotetradecane were monitored upon illumination of the anthracenyl chromophore at 360 nm in the presence of a large excess of thiocyanate. The trans-[CoL(NO₂)(ONO)]⁺ complex underwent a ligand exchange reaction in the absence of light and displayed an enhancement of the reaction upon illumination. In contrast the cis-[CoL(NO₂)(ONO)]⁺ complex was stable in the dark but displayed a significant quantum yield of photoactivated ligand release (Φ = 0.19). It is proposed that in cis-[CoL(NO₂)(ONO)]⁺ the photoexcited anthracenyl chromophore undergoes efficient energy transfer to the cobalt(iii) cyclam before ligand exchange. Complexes based on the anthracenylcyclam–cobalt(iii) framework may be potentially useful candidates as photoactivated ligand release systems.

Acknowledgements

We thank the Australian Research Council for financial support of this work.

References

Photochemistry of Anthracene-Appended Cobalt(iii) Cyclam Complexes

Abstract

Acknowledgements

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