For study of oxygenation phenomena, molecular oxygen in its excited state (1-O-2) can be generated either by irradiation of ordinary oxyen (3-O-2) in the presence of a sensitizer (dye) or by chemical means. All available methods introduce their own side reactions that complicate interpretations especially those on model systems of biological relevance. Therefore, an important research goal is to develop new ways to convert 3-O-2 leads to 1-O-2. This project concerns interactions of ground state and excited oxygen with strained Pi bonds. Specific encumbrances in these substrates will reveal structural features that can promote intersystem crossing of the two spin states of oxygen without permanently capturing either one of them. The findings could allow ultimate design of a """"""""catalyst"""""""" capable of converting triplet oxygen to singlet oxygen by simple thermal contact and not requiring light, or dyes, or harsh chemical reagents. Types of compounds perceived as good candidates for catalyst design include: trans, trans bicyclic alkenes and their heteroatom derivatives; bicyclic allenes with and without heteratoms; and tetralkylated alkenes that are congested and deformed by rigid cage networks. Representatives of these classes will be synthesized and their behavior toward 3-O-2 and 1-O-2 investigated. Subtle factors that influence dioxetane lability will be revealed. New methodology to prepare these classes of compounds will be explored and developed, including specialized photochemical reactions that bring about skeletal rearrangements. The details of how Pi bonds interact with 3-O-2 and 1-O-2 to produce dioxetanes need to be understood in order to design a possible calytic converter that would benefit research in chemistry and biology. It has become recognized that singlet oxygen is an important species in photodynamic action and may be implicated in many cellular events related to cancer-producing mechanisms, bactericidal activity of phagocytes, certain blood diseases, possible free radical-like aging mechanisms, metabolic hydroxylations, as well as in photooxidative degradation of biopolymers, photoreactions of atmospheric pollutans, etc.
