G‐Quadruplex Supramolecular Assemblies in Photochemical Upconversion

Parallel, tetramolecular G‐quadruplex (G4) DNA possessing TINA monomer, ( R )‐1‐ O ‐[4‐(1‐pyrenylethynyl)phenylmethyl]glycerol, were synthesised and evaluated in complexes with tris(2,2′‐bipyridine)ruthenium(II), [Ru(bpy) 3 ] 2+ , and the Zn 2+ derivative of 5,10,15,20‐tetrakis‐(1‐methyl‐4‐pyridyl)‐21  H ,23 H ‐porphine, ZnTMpyP4. UV/Vis, fluorescence, and circular dichroism (CD) spectroscopy showed that the use of G4‐DNA as a template resulted in the effective communication between the ligands and the TINA molecule that was covalently attached to the 5′‐end and between T and dG at the 5′‐end of the dTG 4 T sequence. Only one G4‐DNA possessing the TINA molecule at the 5′‐end of the dTG 4 T sequence was able to yield a green‐to‐blue photochemical upconversion (PUC, λ em =420 nm) in the presence of [Ru(bpy) 3 ] 2+ upon excitation at 500 nm. Different DNA secondary structures can thus be used in DNA‐based assemblies for PUC and the way of attachment of chromophores to DNA plays a pivotal role for the creation of a photosynthetic centre.