These unique nanoparticles were developed at Northwestern University, USA, and used as building blocks for electrostatic self-assembly of nanoparticle suprastructures (Science 2006, 312, 420; Nano Lett. 2007, 7, 1018). They are water soluble and, unlike NPs coated with primary-amine thiols (cf. product Au_55_C11_NH2) are electrically charged over the entire range of pH’s (J. Am. Chem. Soc. 2006, 128, 15046). Owing to their cationic character, they can also be used to immobilize (via physisorption) anionic species such as DNA (J. Am. Chem. Soc. 2001, 123, 7626).

Figure: Nanoparticle (NP) supracrystals composed of 50% Au/COOH NPs (5.5 nm) and 50% Ag/N(CH3)3+ NPs (5.5 nm) prepared using ProChimia’s thiols. These AB crystals have an unusual diamond lattice structure (see Science 2006, 312, 420). The bottom row shows macroscopic sphalerite and diamond crystals of the same morphologies. Courtesy of the Grzybowski Lab, Northwestern University, USA.