Polyesters were rapidly formed employing the interfacial condensation of Group VB and vanadocene dihalides with 3,5-purinedicarboxylic acid. Infrared spectroscopy shows the formation of metalÀoxygen bonds. The products have a largely distorted non-bridging geometry about the metal atom. Matrix-assisted laser desorption/ionization mass spectrometry results are consistent with the formation of the polyesters. The polymers exhibit inhibition of the growth of pancreatic, colon, breast, and prostate cancer cell lines.