Cyclometallated platinum(II) complexes as luminescent switches for calf-thymus DNA

Abstract

Intercalation of [PtII(dpp-C,N,N′)(MeCN)]+ 1 (dpp-C,N,N′= C-deprotonated 2,9-diphenyl-1,10-phenanthroline) and [PtII2(phy-C,N,N′)2(µ-dppm)]2+ 2 (pby-C,N,N′) C-deprotonated 6-phenyl-2,2′-bipyridine, dppm = diphenylphosphinomethane) into calf-thymus DNA leads to a dramatic enhancement of the photoluminescence of the platinum(II) complexes (I/I0= 271 1, 117 2); a much weaker DNA binding affinity of 2 [K=(4.2 ± 0.3)× 104 dm3 mol–1] than of 1 [K=(1.0 ± 0.1)× 106 dm3 mol–1] is observed.