Structure in solid state of 3,3′-diindolylmethane derivatives, potent cytotoxic agents against human tumor cells, followed X-ray diffraction and 13C CP/MAS NMR analyses

The 5,5′-disubstituted-3,3′-diindolylmethanes 1, 2 have been prepared and their structure was analyzed by X-ray and NMR techniques. The X-ray diffraction studies revealed interesting C-H⋯π intermolecular interactions which may play role in characterization of their biological features. In 1H and 13C NMR spectra in solution and in 13C CPMAS NMR spectra in solid state only a single pattern of signals was observed. Both compounds reduce the growth of MCF7 (breast), NCI-H460 (lung), and SF-268 (NCS) cells dramatically.