Chemical and structural diversity in eumelanins : unexplored bio-optoelectronic materials

A review. A black whole: The black insol. biopolymer eumelanin is prepd. through the oxidative polymn. of 5,6-dihydroxyindoles (see scheme). It has a largely unknown heterogeneous structure and unique optoelectronic properties. Current structural models are presented and possible applications are discussed. Eumelanins, the characteristic black, insol., and heterogeneous biopolymers of human skin, hair, and eyes, have intrigued and challenged generations of chemists, physicists, and biologists because of their unique structural and optoelectronic properties. Recently, the methods of org. chem. have been combined with advanced spectroscopic and imaging techniques, theor. calcns., and methods of condensed-matter physics to gradually force these materials to reveal their secrets. Herein we review the latest advances in the field with a view to showing how the emerging knowledge is not only helping to explain eumelanin functionality, but may also be translated into effective strategies for exploiting their properties to create a new class of biol. inspired high-tech. materials.