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)(4)N](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 prepared by reaction of {CdSe[n-C12H25S](0.23)[Na](0.23)} or {CdSe[Cd(n-dodecanethiolate)(2)](0.22)} QBs with n-dodecanethiol. Thus, interchange of n-dodecanethiol and n-dodecanethiolate ligation is readily achieved.