Functional Molecular Crystals in Biology

Abstract

Abstract Highly reflective crystals of small organic molecules are the functional materials in a wide variety of optical systems in animals. We present a perspective on this field of organic biomineralization and review evidence for the widespread distribution of organic crystals in animals. These materials were, until recently, largely overlooked principally because the crystals are lost during conventional electron microscopy preparation procedures. We document the discovery of the crystalline pteridines as a new class of biological crystals and explain why many more organic biocrystals will likely be discovered and where they may be found. We examine the chemical basis for the extraordinary optical properties of the crystals and review some of their newly discovered biological functions. The study of biogenic molecular crystals promises to yield fascinating insights into photonic systems in animals and will inspire the development of artificial optical materials.