Cis-platin and trans-platin are isomers of the platinum II complex with the chemical formula Pt NH3 2Cl2. The structural difference between the two lies in the spatial arrangement of the ligands around the central platinum atom.In cis-platin, the two ammine NH3 ligands and the two chloride Cl- ligands are positioned adjacent to each other, forming a square planar geometry. In trans-platin, the ammine ligands are positioned opposite each other, as are the chloride ligands, also forming a square planar geometry but with a different spatial arrangement.This structural difference has a significant impact on their biological activity as chemotherapy agents. Cis-platin is a widely used and effective chemotherapy drug, while trans-platin is much less effective. The reason for this difference in activity lies in their ability to form covalent bonds with DNA.Cis-platin forms intrastrand cross-links between adjacent purine bases guanine and adenine in DNA, causing the DNA strands to bend and kink. This distortion interferes with DNA replication and transcription, ultimately leading to cell death. Cis-platin's ability to form these cross-links is due to its cis configuration, which allows the two chloride ligands to be in close proximity to each other and thus bind to adjacent purine bases.Trans-platin, on the other hand, is much less effective at forming these intrastrand cross-links due to its trans configuration. The spatial arrangement of the chloride ligands in trans-platin makes it difficult for them to bind to adjacent purine bases, resulting in a much lower biological activity compared to cis-platin.In summary, the structural difference between cis-platin and trans-platin is the arrangement of their ligands around the central platinum atom. This difference affects their ability to form intrastrand cross-links with DNA, which in turn influences their biological activity as chemotherapy agents. Cis-platin is a highly effective chemotherapy drug due to its ability to form these cross-links, while trans-platin is much less effective.