An overview, primarily on our own findings, is given on the structural and physicochemical properties of exotic chlorophylls, including pheophytins, that function as minor but key components in the photosynthetic reaction centers. Such unusual chlorophylls are decisive in characterizing the molecular assembly for primary charge separation and subsequent redox processes in individual photosystems. A naturally occurring Zn-bacteriochlorophyll a is also discussed in view of its structure, physicochemical properties and biological implications.