Student Researchers: Jason A. Payne and Alexa N. Ivancic

Introduction

Singlet oxygen, ¹O₂, is an excited form of molecular or ground state oxygen which is in the air we breathe. This high energy oxidant has been shown to cause oxidative damage in the human body through the processes of cancer and aging. With the study of singlet oxygen reactions, we gain an insight into the mechanisms of these harmful reactions. Singlet oxygen has also been utilized to combat tumor cells through photodynamic therapy.

Singlet oxygen can be generated easily in the laboratory through photosensitization, Eqn 1. A sensitizer (¹TPP) is irradiated with visible light which forms the excited sensitizer (¹TPP*) which then transfers its energy to ground state molecular oxygen forming ¹O₂ and regenerating ¹TPP.

Our Current Research

One of the major reaction pathways that ¹O₂ undergoes is the "ene" reaction, Scheme 1. Simple alkenes with allylic hydrogens react with ¹O₂ to form a hydroperoxide. This reaction is generally accepted to occur through a perepoxide intermediate. Our group is interested in utilizing aqueous and hydroxylic solvents in the ene reaction and determining the effects on the intermediate perepoxide. Our work can be used to help understand the mechanism of oxidative damage in biological systems including the human body which is approximately 60% water.

Scheme 1. The singlet oxygen "ene" reaction of tiglic acid