This invention provides novel high density memory devices that are electrically addressable permitting effective reading and writing, that provide a high memory density (e.g., 1015 bits/cm3), that provide a high degree of fault tolerance, and that are amenable to efficient chemical synthesis and chip fabrication. The devices are intrinsically latchable, defect tolerant, and support destructive or non-destructive read cycles. In a preferred embodiment, the device comprises a fixed electrode electrically coupled to a storage medium comprising one or more thiol-derivatized porphyrins. The storage medium has a multiplicity of different and distinguishable oxidation states and data is stored in said oxidation states by the addition or withdrawal of one or more electrons from the storage medium via the electrically coupled electrode(s).