G-quadruplex nucleic acid structures have long been studied as potential anticancer targets while their potential in antiparasitic therapy has only recently been recognized but barely explored. Herein we report the synthesis, biophysical characterization and in vitro screening of a series of stiff-stilbene G4 binding ligands featuring differing electronics, side-chain chemistries and molecular geometries. The ligands display selectivity for G4 DNA over duplex DNA and exhibit nanomolar toxicity against Trypasanoma brucei and HeLa cancer cells whist remaining up to two orders of magnitude less toxic to non-tumoral mammalian cell line MRC5. Our study demonstrates that stiff-stilbenes show exciting potential as the basis of selective anticancer and antiparasitic therapies. In order to achieve the most efficient G4 recognition the scaffold must possess the optimal electronics and substitution pattern and correct molecular geometry.