Helquat-induced chiroselective aggregation of Au NPs

Au nanoparticles (NPs) are functionalized with chiral (R) or (S) binaphthol phenylboronic acid ligands, (1a) or (1b). The (R)- or (S)-binaphthol phenylboronic acid ligands form donor-acceptor complexes with the chiral dicationic helicene, helquat (P)-HQ2+ or (M)-HQ2+, (2a) or (2b). The association constants between (1a)/(2a) and (1a)/(2b) correspond to (7.0 ± 0.5) × 105 M-1 and (2.5 ± 0.3) × 105 M-1, respectively, whereas the association constants between (1b)/(2b) and (1b)/(2a) correspond to (4.0 ± 0.5) × 105 M-1 and (1.8 ± 0.3) × 10 5 M-1, respectively. Chiroselective aggregation of chiral binaphthol phenylboronic acid-capped Au NPs triggered by the chiral helquats, is demonstrated. © 2012 American Chemical Society.