Herein we present the functionalization of freestanding silicon nanosheets (SiNSs) by radical-induced hydrosilylation reactions. An efficient hydrosilylation of Si-H terminated SiNSs can be achieved by thermal initiation or the addition of diazonium salts with a variety of alkene or alkyne derivatives. The radical-induced hydrosilylation is applicable for a wide variety of substrates with different functionalities, improving the stability and dispersibility of the functional SiNSs in organic solvents and potentially opening up new fields of application for these hybrid materials.

The reactivity of diazonium salts towards freestanding, photoluminescent silicon nanocrystals (SiNCs) is reported. It was found that SiNCs can be functionalized with aryl groups by direct reductive grafting of the diazonium salts. Furthermore, diazonium salts are efficient radical initiators for SiNC hydrosilylation. For this purpose, novel electron-deficient diazonium salts, highly soluble in nonpolar solvents were synthesized. The SiNCs were functionalized with a variety of alkenes and alkynes at room temperature with short reaction times.

We present a method to combine the functional features of poly(diethyl vinylphosphonate) (PDEVP) and photoluminescent silicon nanocrystals. The polymer-particle hybrids were synthesized in three steps through surfaceinitiated group transfer polymerization using Cp 2 YCH 2 TMS-(thf) as a catalyst. This pathway of particle modification renders the nanoparticle surface stable against oxidation. Although SiNC properties are known to be sensitive toward transition metals, the hybrid particles exhibit red photoluminescence in water. The temperature-dependent coiling of PDEVP results in a change of the hydrodynamic radius of the hybrid particles in water. To the best of our knowledge, this is the first example of controlled catalytic polymerization reactions on a silicon nanocrystal surface.

Hydride-terminated photoluminescent silicon nanocrystals (SiNCs) were functionalized with organolithium compounds. The reaction is proposed to proceed through cleavage of Si - Si bonds and formation of a Si - Li surface species. The method yields colloidally stabilized SiNCs at room temperature with short reaction times. SiNCs with mixed surface functionalities can be prepared in an easy two-step reaction by this method by quenching of the Si - Li group with electrophiles or by addressing free Si - H groups on the surface with a hydrosilylation reaction.

We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place.