Poly(3‐hexylthiophene)s Functionalized with N‐Heterocyclic Carbenes as Robust and Conductive Ligands for the Stabilization of Gold Nanoparticles

Abstract

Recently, N‐heterocyclic carbenes (NHCs) are explored as anchor groups to bind organic ligands to colloidal gold (i.e. gold nanoparticles, Au NPs), yet these efforts are confined to non‐conjugated ligands so far—that is, focused solely on exploiting the stability aspect. Using NHCs to link Au NPs and electronically active organic components, for example, conjugated polymers (CPs), will allow capitalizing on both the stability as well as the inherent conductivity of the NHC anchors. Here, we report three types of Br‐NHC‐Au‐X (X=Cl, Br) complexes, which, when used as starting points for Kumada polymerizations, yield regioregular poly(3‐hexylthiophenes)‐NHC‐Au (P3HTs‐NHC‐Au) with narrow molecular weight distributions. The corresponding NPs are obtained via direct reduction and show excellent thermal as well as redox stability. The NHC anchors enable electron delocalization over the gold/CP interface, resulting in an improved electrochromic response behavior in comparison with P3HT‐NHC‐Au.

Abstract

Br‐NHC‐Au ^I complexes were designed as starting points of Kumada polymerizations to grow regioregular poly(3‐hexylthiophene)s‐NHC‐Au ^I, which were reduced to afford P3HT‐NHC@Au NPs. In addition to excellent thermal as well as redox stability, the corresponding NPs show improved charge transfer behavior due to the effective electron delocalization over the gold/P3HT interface benefiting from the robust and conductive NHC linkages.