Following this proof-of-concept, we extended the study to investigate a more complex G4 DNA model. Elegant structural work from Phan, Ritcher et al. reported the distinctive structural features of LTR-III, which is the major G-quadruplex conformation observed in vitro of all the G-quadruplexes formed in the HIV-1 LTR sequence. Their NMR studies of LTR-III in K + solution revealed the formation of a unique quadruplex-duplex hybrid consisting of a three-layer (3 + 1) G4 scaffold, a 12-nt diagonal loop containing a conserved duplex-stem, a 3nt lateral loop, a 1-nt propeller loop, and a V-shaped loop. The team proposed this unique quadruplex-duplex junction as potential druggable target and we considered it worthy of investigation as a potential candidate for targeting with a photoresponsive G4 ligand.