Partial charge transfer in the salt co-crystal of l-ascorbic acid and 4,4'-bi-pyridine.

In the title 1:2 co-crystal, CHN ·(CHO·CHO), l-ascorbic acid (LAA) and 4,4'-bi-pyridine (BPy) co-crystallize in the chiral space group 2 with two mol-ecules of LAA, and one mol-ecule of bpy in the asymmetric unit. The structure was modeled in two parts due to possible proton transfer from LAA to the corresponding side of the bpy mol-ecule having an occupancy of approximately 0.25 and part 2 with an occupancy of approximately 0.