Photoluminescent silicon nanocrystals with chlorosilane surfaces – synthesis and reactivity

Abstract

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.

Radical‐Induced Hydrosilylation Reactions for the Functionalization of Two‐Dimensional Hydride Terminated Silicon Nanosheets

“…150 8C. [25,35,39] thickness of the 1-hexene-functionalized SiNSs reported by Nakano et al [23] XRD patternsr ecorded from the non-functionalized and 1dodecene-functionalized SiNSs showt hat the characteristicr e-flections of the stacked, non-functionalized sheets decrease significantly in intensity when the SiNSs are functionalized withoutt he initiator and even furtherw ith radicali nitiation ( Figure S8 in the Supporting Information). The long dodecyl chains on the surface seem to stabilizet he monolayers and hinder the SiNSs from stacking, resulting in al esso rdered material.…”

“… Proposed mechanism for the: a) diazonium‐compound induced mechanism and thermally induced hydrosilylation at temperatures between b) 80–150 °C, and c)≥150 °C …”

Silicon Nanocrystals and Silicon‐Polymer Hybrids: Synthesis, Surface Engineering, and Applications

“…[46] While diazonium salts have been used to directly graft aryl groups onto silicon surfaces, [47] their use as radical initiators has only been shown for porous silicon. [49] Figure 1. a) NALDI mass spectra of dodecyl-functionalized Si-NCs at the indicated temperatures. [49] Figure 1. a) NALDI mass spectra of dodecyl-functionalized Si-NCs at the indicated temperatures.…”

“…[48] Theresearchers also investigated the influence of substituents on the efficacyo ft he reaction and found that those with electron-withdrawing groups provided the highest surface coverage.D iazonium-salt-initiated hydrosilylation was also tolerant of various functional groups and afforded attachment of hydrocarbon alkenes and alkynes,v inyl laurate,m ethyl methacrylate,e thynyltrimethylsilane,a nd chlorodimethyl-(vinyl)silane.I na nother study,t he same researchers demonstrated that chlorodimethyl(vinyl)silane functionalized Si-NCs could be further modified upon reaction with alcohols, silanols,a nd organolithium reagents. [49] Reproducedand adapted with permission from the American Chemical Society. [37,38]…”

Silicium‐Nanokristalle und Silicium‐Polymer‐Hybridmaterialien: Synthese, Oberflächenmodifikation und Anwendungen

“…Zusätzlich zeigten die Autoren, dass Chlordimethyl(vinyl)silan-funktionalisierte SiNKs eine weitere Funktionalisierung mit Alkoholen, Silanolen und Organolithiumreagentien zulassen. [49] 2.2. Alternative Reaktionen auf der Silicium-Hydridoberfläche Obwohl Hydrosilylierung die hauptsächlich eingesetzte Herangehensweise zur Oberflächenfunktionalisierung von SiNKs ist, wurden in der Literatur weitere Methoden beschrieben (Schema 5).…”