The oxygen-organic molecule photosystem: revisiting the past, recalibrating the present, and redefining the future.

Perturbation by a neighboring molecule M appreciably alters the properties of both the ground and excited states of molecular oxygen, as reflected in a variety of photophysical phenomena. In this article, we build upon the ~ 100 year history of work in this field, illustrating how the M-O 2 system continues to challenge the scientific community, facilitating better insight into fundamental tenets of chemistry and physics.