Taming of Singlet Oxygen: Towards Artificial Oxygen Carriers Based on 1,4-Dialkylnaphthalenes

Naphthalene endoperoxides are known as convenient sources of singlet oxygen (O-2, (1)Delta(g)), which is the major product of endoperoxide cycloreversion reaction. However, their potential as carriers of ground-state molecular oxygen (O-2, (3)sigma(g)) similar to artificial oxygen carriers remains largely unexplored. This is due to the extreme reactivity and cytotoxic effects of the released singlet oxygen. We now report that a compound with a bimodular design, which incorporates an endoperoxide and an efficient physical quencher of singlet oxygen, 1,4-diazabicyclo[2.2.2]octane (DABCO), produces exclusively ground-state molecular oxygen. This result, coupled with the fact that oxygen release rates from endoperoxides are highly amenable to fine-tuning in a very broad range, and open to targeting by ligand attachment, raises the potential of these compounds far above any comparable chemical, or even biochemical sources. In cell culture experiments, we showed that the addition of the endoperoxide-quencher conjugate can enhance and sustain cell proliferation.

Automated summary

Naphthalene endoperoxides are convenient sources of singlet oxygen but their potential as ground-state molecular oxygen carriers remains largely unexplored. A compound with a bimodular design, incorporating an endoperoxide and a physical quencher of singlet oxygen, produces exclusively ground-state molecular oxygen. This compound shows potential as a highly tunable and targetable oxygen carrier in cell culture experiments, enhancing and sustaining cell proliferation.