ABSTRACT
Light is used by bioorganisms for two major purposes: sensory perception and energy conversion. The functional requirements of molecular devices are drastically different for these two purposes. The former demands sensitivity and a wide dynamic range of photon energy detection, and the latter demands efficiency of photon energy conversion. Superficially, there seems to be a dichotomy of nature’s choice of molecular materials for these two diverse functions: visual membranes utilize retinal as the chromophore, whereas photosynthetic membranes utilize magnesium porphyrin as the chromophore. Fundamentally, there are features in common to these two types of photobiological membranes. In Chapter 128, light-induced charge separation and the photoelectric effect are examined in detail. In this chapter, we will consider the molecular switching processes in these two diverse systems from a broad perspective.
