A photolabile ligand for light-activated release of caged copper.

Journal Article

A photosensitive caged copper complex has been prepared from a tetradentate ligand (H2cage) composed of two pyridyl-amide arms connected by a photoreactive nitrophenyl group. H2cage binds Cu2+ in aqueous solution with a stability constant (log beta) of 10.8, which corresponds to a KD of 16 pM at pH 7.4. The neutral Cu2+ complex, [Cu(OH2)(cage)], crystallizes as a distorted trigonal bipyramid coordinated by two amide and two pyridyl N atoms, with a water molecule bound in the trigonal plane. Photolysis with 350 nm UV light cleaves the ligand backbone to release photoproducts with significantly diminished affinity for Cu2+, thereby uncaging the metal ion. When coordinated as the caged complex, copper has diminished reactivity to produce hydroxyl radicals from Fenton-like reaction mixtures containing hydrogen peroxide and ascorbic acid. Postphotolysis, uncaged copper promotes hydroxyl radical formation under the same conditions. The strategy of caging copper is promising for applications where light could be used to trigger release of copper as a pro-oxidant to increase oxidative stress or as a tool to release copper intracellularly to study mechanisms of copper trafficking.

Full Text

Duke Authors

Cited Authors

  • Ciesienski, KL; Haas, KL; Dickens, MG; Tesema, YT; Franz, KJ

Published Date

  • September 17, 2008

Published In

Volume / Issue

  • 130 / 37

Start / End Page

  • 12246 - 12247

PubMed ID

  • 18714999

Electronic International Standard Serial Number (EISSN)

  • 1520-5126

Digital Object Identifier (DOI)

  • 10.1021/ja8047442


  • eng

Conference Location

  • United States