Platinum Complexes and Cancer Treatment It is a common misconception that scientific research works the same vay as technology, where goals are set and the appropriate solutions found. In science, however, there is so much that is not known that we still rely to a large extent on observing the unexpected. It was in 1965 that Barnett Rosenberg of Michigan State University ing the rate of bacterial growth in the presence of electrie fields, Both he and his coresearchers were surprised to find that the bacteria in electric fields were growing without dividing. The group spent a considerable amount of time looking for possible causes of this, such as pH changes, temperature changes, and so on. Having excluded every probable cause, they examined the electrodes that they were using to generate the electric charge. These were made of platinum, a metal that was"well known"to be extremely unreactive However, their tests showed that some of the platinum metal was being oxidized, and it was the oxidation products, the diammine dichloroplatinum(Il), PtCL, (NH,)2, and diamminetetrachloro platinum(IV), PtCL(NH,)2, molecules that were causing the bacterial abnormalities. Further, only the cis geometric isomers were active. This biological activity of platinum compounds was completely unexpected Because they prevented cell division, the compounds were tested for antitumor activity, and the cis-diamminedichloroplatinum(II) com pound seemed particularly effective. The compound is now available for cancer treatment under the name cisplatin. It does have side effects; and hemists, now that they are aware of the potential of platinum com pounds, are looking for more effective and less toxic analogs. The key to this compound s effectiveness seems to be the ability of the cis- (H N), Pt unit to link DNA units, thereby preventing turther DNA syn thesis. The trans isomers show no biological activity. Hence these com- pounds demonstrate the influence of isomerism on the chemical behavior of compounds. 277277