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

Abstract

Intercalation of [Pt^II(dpp-C,N,N′)(MeCN)]⁺ 1 (dpp-C,N,N′= C-deprotonated 2,9-diphenyl-1,10-phenanthroline) and [Pt^II₂(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.