Chapter 8: Activatable Photosensitizers

The controlled generation of singlet oxygen is of great interest owing to its potential. The specificity of ¹O₂ generation is controlled by three factors: light, O₂ and a photosensitizer. Yet, nowadays some applications still require even further specificity. A possible solution is to introduce a fourth factor that can establish a control mechanism by means of an external stimuli. In this chapter, the main activation mechanisms of photosensitizers will be covered: self-quenching, energy and electron transfer and ¹O₂ scavengers. Some external stimuli are necessary to activate this fourth factor. Examples of these are: molecular recognition, enzymes, pH, small molecules, light activation, viscosity and even a combination of them.