Structural characterization of di-indol-3-yl disulfide derivatives, potential antitumoral agents

Di-5-X-indol-3-yl disulfides (X = H 1, F 2, Br 3, I 4, OCH3 5) were synthesized and their solid state structures were probed by 13C CP/MAS NMR spectroscopy. All disulfides adopt a layered conformation and both indole rings in one molecule were assumed to have very similar structural parameters, which is in agreement with a simple spectral pattern. For compounds 1 and 5 X-ray diffraction results are also presented. In the crystals of 1 and 5, the packing of the molecules is stabilized by dissimilar weak intermolecular interactions: in 1 dominate the N1–H1⋯π intermolecular hydrogen bonds and in 5 the C2–H2⋯O10 intermolecular hydrogen bonds predominate. The di-5-fluoroindol-3-yl disulfide 2 and di-5-iodoindol-3-yl disulfide 4 were found to reduce considerably the growth of prostate cancer cell PC-3.