Cisplatin is more effective in treating cancer compared to transplatin. The difference in their effectiveness is due to the isomerism of the coordination compounds, specifically their geometrical isomerism.Cisplatin has a square planar structure with two adjacent chloride ions and two adjacent ammine ligands NH3 . Transplatin, on the other hand, has a similar square planar structure but with the chloride ions and ammine ligands positioned opposite to each other.The biological activity of these compounds is mainly attributed to their ability to bind to DNA, causing DNA damage and inhibiting replication, which ultimately leads to cell death. Cisplatin preferentially forms 1,2-intrastrand crosslinks between adjacent purine bases guanine and adenine in DNA. This causes a bend in the DNA helix, which disrupts the normal function of the DNA and triggers cellular repair mechanisms. If the damage is too severe, the cell undergoes apoptosis, or programmed cell death.Transplatin, however, forms less effective 1,3-intrastrand crosslinks and interstrand crosslinks, which do not cause significant distortion to the DNA helix. As a result, transplatin is less effective in inhibiting DNA replication and inducing cell death.In summary, the geometrical isomerism of cisplatin and transplatin plays a crucial role in their biological activity. Cisplatin's ability to form 1,2-intrastrand crosslinks with DNA makes it a more effective anticancer agent compared to transplatin.