A superconductor has a set of electrons that go to a super electron wave state. The wave functions of the individual electrons overlap so it becomes impossible to distinguish one electron from another. If you have a loop of superconducting material with a 2 pi phase change as you go around the circuit,
the loop will trap one quantum of magnetic flux with an endlessly circulating current. You have to break the circuit and the super electron wave function to get magnetic flux in or out.
Aromatic organic compounds have loops of (4N + 2) carbon-carbon bonds. These are often drawn as alternate single and double bonds, but what you actually have is a single sigma bond and cloud of overlapping pi electron wave functions in a common energy state. Sounds a bit like a superconducting loop, doesn't it?
The simplest aromatic compound is benzine. In theory, you could link a flux quantum into a benzine molecule, but you would need a big magnetic field (2 Tesla?) and some way of busting up the pi orbitals so the flux can get in.
Porphyrins are square molecules with an 18-element aromatic ring. This has five or six times the area of benzine, so the magnetic field would go down in proportion. You can trap a metallic atom in the centre of the ring: something like cobalt or iron might stabilise the magnetic field.
How do you get the magnetic field in? If you heat up the porphyrin molecule in a strong magnetic field, the vibrations can bend the molecule out of being flat, which breaks the pi delocalisation, and lets the flux quantum slip in. You will then have a mixture of the ordinary porphyrin and the first magnetic isomer. The magnetic molecules may stack and crystallise out.
Another thing you could do is to stick chemical groups at the porphyrin corners, so the squares might self-assemble into tapes. You now have molecular-sized magnetic tape where each square has three possible states.
A mole of bits is a lot of memory.