Defying chemical equilibrium with light

Chemical systems capable of exploiting an energy source to function away from thermodynamic equilibrium are a hallmark of the biological world. The design and operation of artificial versions of such systems constitute a stimulating and highly challenging scientific goal with considerable expectations for application in synthetic chemistry, catalysis, materials science, energy conversion, and medical therapy. In this context, supplying energy in the form of photons has several elements of conceptual interest and practical advantage. Here we present the progress of research over the past 5 years on artificial molecular-based systems that can use light energy to operate away from equilibrium – an emerging field that has just begun to express its innovative potential.