Anthracenyl‐Hydrazinyl‐Thiazolo Arene Ruthenium Complexes Coupled to Photosensitizers as PDT Agents

Four anthracenyl‐functionalized hydrazinyl‐thiazolo pro‐ligands ( L 1 ‐ L 4 ) have been synthesized and characterized. Complexation to p‐ cymene ruthenium units has been conducted in methanol, affording four p ‐cymene ruthenium complexes [Ru( p ‐cymene)( η 2 ‐ L )Cl]Cl (abbreviated [ RuL 1‐4 Cl]Cl). The ligands are coordinated to ruthenium by two nitrogen atoms, thus forming five‐membered metalla‐cycles. Then, these four arene ruthenium piano‐stool complexes ( RuL 1‐4 ) were coordinated at the periphery of three pyridyl‐functionalized porphyrin compounds, 5‐pyridyl‐10,15,20‐triphenylporphyrin ( MPP ), 5,15‐dipyridyl‐10,20‐diphenylporphyrin ( DPP ), and 5,10,15,20‐tetrapyridylporphyrin ( TPP ), after removal of the chlorides in [ RuL 1‐4 Cl]Cl by addition of silver triflate, to produce the corresponding dicationic [ MPP ( RuL 1‐4 )] 2+ , tetracationic [ DPP ( RuL 1‐4 ) 2 ] 4+ and octacationic complexes [ TPP ( RuL 1‐4 ) 4 ] 8+ . All organic molecules ( L 1 ‐ L 4 , MPP , DPP , TPP ), organometallic complexes ([ RuL 1‐4 Cl]Cl), as well as the 12 porphyrin arene ruthenium systems [ MPP ( RuL 1‐4 )](CF 3 SO 3 ) 2 , [ DPP ( RuL 1‐4 ) 2 ](CF 3 SO 3 ) 4 and [ TPP ( RuL 1‐4 ) 4 ](CF 3 SO 3 ) 8 have been tested as anticancer agents on the colon cancer cell line HCT116. In addition to cytotoxicity, the phototoxicity of the porphyrin‐containing derivatives MPP ( RuL 1‐4 ), DPP ( RuL 1‐4 ) 2 and TPP ( RuL 1‐4 ) 4 , together with MPP , DPP , TPP, and [ RuL 1‐4 Cl]Cl, were evaluated under blue (420 nm, 20 J/cm 2 ), green (527 nm, 72 J/cm 2 ), and red (630 nm, 71 J/cm 2 ) light, showing a phototoxicity in the lower nanomolar range as well as excellent phototoxic indexes.