Water soluble luminescent cyclometalated platinum(II) complex — A suitable probe for bio-imaging applications

Abstract

A highly water soluble platinum(II) complex, [Pt(ppy)(en)]Cl, (where ppy = 2-phenylpyridine and en = ethane-1, 2-diamine) with a strong green luminescence in solution was synthesized in two steps. Initially, an intermediate complex, [Pt(ppy)(ppyH)(Cl)], 1 was isolated which was transformed into the light-emitting mononuclear platinum(II) complex, [Pt(ppy)(en)]Cl, 2. The green emission of 2 was changed into yellow in their solid state. The strong π…π intermolecular interactions that interplays between the phenyl rings lying into the two consecutive molecules which led to the solid state emission. The low cytotoxicity of 2 ensures the feasibility for using these in bioimaging probe. The testing bioimaging results demonstrate that the compound penetrates the cell membrane in both cancer (HeLa, U87MG and Nuro2a) and normal cells (CHO-K1 and 3T3-L1). The cellular uptake was observed to much higher in cancerous cells only. Co-localization study confirmed the localization of it into the cell nucleus.