A tunable library of thiourea precursors will be described that can be easily synthesized in one step from commercially available isothiocyanates with primary or secondary amines. We describe the use of these thioureas in a hot-injection synthesis of lead sulfide and cadmium sulfide by reacting the thiourea with the corresponding metal carboxylate. Using PbS as a model system, we explore the influence of thiourea structure on precursor conversion rate, observing control over 3 orders of magnitude within a family of disubstituted precursors. Quantitative conversion of the thiourea and slow Ostwald ripening, allows the final nanocrystal size to be determined by the choice of precursor over a range diameters  8 nm. The reaction is also easily scaled allowind PbS nanocrystals to be prepared multi-gram quantities. Easy-to-use libraries of precursors like these will improve the reproducibility of nanocrystal syntheses and purification procedures and lead to greater understanding of crystallization mechanisms.

Rapid access to substituted thioureas: A tunable library of precursors for metal sulfide nanocrystals

248th National Meeting (2014)

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