Proposed is the development of a family of cyclometalated Rh(III) intercalators to target and photocleave DNA base pair mismatches. Cyclometalated complexes of the type [Rh(ppy)2(chrysi)]1+ will be studied and, as a result of their lower charge compared to other rhodium interclators, are expected to be less toxic and have greater biomobility. DNA mismatch recognition and photoreaction with [Rh(ppy)2(chrysi)]1+ will be examined on DNA oligonucleotides, plasmids and in mismatch repair deficient cells.