2-Formyl-, 2-acetyl-, and 2-benzoylpyridine N(4)-substituted thiosemicarbazones possess substantial in vitro activity against various human tumor lines. Unfortunately, their lack of solubility in aqueous solutions causes these thiosemicarbazones and their metal complexes to show less promising in vivo activity. However, when the N(4)-substituted thiosemicarbazone moiety is attached to an amide carbon, greater solubility in polar solvents is realized. Reduction of 2-cyanopyridine by sodium in dry methanol in the presence of a thiosemicarbazide produces 2-pyridineformamide thiosemicarbazones. A large number of complexes with a variety of metal ions have been prepared and structurally, as well as spectrally, characterized; coordination is most often via the pyridyl nitrogen, imine nitrogen and thiolato or thione sulfur when coordinating as the anionic or neutral ligand. N(4)-substituted bis(thiosemicarbazones) derived from 1,2-diketones and 1,2-aldoketones also have pharmaceutical possibilities, and a large number of these compounds have also been prepared and characterized in addition to with their metal complexes. Coordination is often via the imine nitrogens and thiolato sulfurs to yield N₂S₂ coordination spheres, but some unique bonding patterns have also been found.

N-heterocyclic-N’-arylthioureas also have potential as pharmaceutical agents and provide a large series of compounds with intramolecular and intermolecular hydrogen bonding. Substitution on one or both rings alters the extent of the hydrogen bonding interactions, as well as the overall planarity of the molecules. An interesting transformation of the thiourea molecules occurs on reaction with copper(II).