Sequential logic and random access memory (RAM): a molecular approach

Since it was first suggested that molecules could be used for information processing, there has been a significant effort to generate systems that behave according to various logic schemes. Here we will summarize and discuss various approaches that serve one common goal: constructing a (bio)-molecular flip-flop. This logic circuit is at the core of random access memory (RAM) and is one of the pillars of sequential logic. We will highlight the concept underlying various approaches towards flip-flops and we will discuss how these constitute and expand the field of molecular logic. This multi-disciplinary approach results in various schemes that range from all photonic systems to transition metal complexes and hybrid nanoparticle/protein-based systems on solid supports.