Polyphenylenepyridyl dendrimers as stabilizing and controlling agents for CdS nanoparticle formation.

Semiconductor nanoparticles (NPs) are being actively explored for applications in medical diagnostics and therapy and numerous electronic devices including solar cells. In this paper we demonstrate the influence of the third generation rigid polyphenylenepyridyl dendrimers (PPPDs) of a different architecture on the formation of well-defined CdS NPs. A high temperature approach to the synthesis of novel CdS/PPPD nanocomposites is feasible due to the high thermal stability of PPPDs. The PPPD architecture affects the CdS NP formation: larger NPs are obtained in the presence of dendrimers with 1,3,5-triphenylbenzene cores compared to those with tetrakis(4-ethynylphen-1-yl)methane cores. The reaction conditions such as concentrations of PPPDs and NP precursors and the temperature regime also influence the CdS NP sizes. For the first time, we elucidated a mechanism of CdS NP formation in a non-coordinating solvent through the CdO redispersion in the presence of PPPDs. Interesting optical properties of these CdS/PPPD nanocomposites make them promising candidates for imaging applications.