Thiol versus Thiolate Ligation on Cadmium Selenide Quantum Belts

Addition of thiols to semiconductor nanocrystals influences their photoluminescence efficiencies; however, the mode of ligation—as neutral thiol ligands or as anionic thiolate ligands—is rarely clearly established. We now differentiate these ligation modes on wurtzite CdSe quantum belts (QBs). n-Dodecanethiol and n-dodecanethiolate ligations of CdSe QBs are obtained through ligand exchanges. Reaction of {CdSe[Cd(oleate)2]0.19} QBs and sodium n-dodecanethiolate affords {CdSe[n-C12H25S]0.23[Na]0.23} QBs, having bound-ion-pair X-type ligation. Reaction of {CdSe[Cd(oleate)2]0.19} QBs and n-dodecanethiol affords {CdSe[Cd(n-dodecanethiolate)2]0.22} QBs, having Cd(n-dodecanethiolate)2 ligands as Z-type ligation. {CdSe[Cd(n-dodecanethiolate)2]0.22} QBs are also prepared by reaction of {CdSe[n-octylamine]0.53} QBs and Cd(n-dodecanethiolate)2. Reaction of {CdSe[Br]0.1[(n-octyl)4N]0.1} QBs and n-dodecanethiol affords {CdSe[n-dodecanethiol]0.26} QBs, having L-type ligation. {CdSe[n-dodecanethiol]0.26} QBs are also pr...