Towards a tunable molecular memory that fits into a (10 A)3 cube.

Using DFT calculations we predict a novel family of small amino acid-based memory-exhibiting molecules, namely complexes of triply deprotonated cysteine (or its derivatives) with selected hexavalent transition metals. We show that the energy difference of the 0 and 1 electromers--corresponding to two chemically distinct oxidation states of a metal, M(VI) and M(IV)--can be tuned towards the thermodynamic equilibrium via deliberate chemical substitutions in the cysteine ligand. Although the thermal stability of both electromers is computed to be rather small at ambient temperatures (due to facile interchange of states 0 and 1 via a low-lying M(V) configuration), we hope to improve stability in related systems. [Figure: see text]. We propose novel kind of tunable molecular memory, based on intramolecular 2e- redox reaction.