Multifunctional alkoxysilanes prepared by thiol-yne "click" chemistry: their luminescence properties and modification on a silicon surface

The photoinitiated radical-based thiol-yne click reaction provides a simple and efficient method for the formulation of diverse alkoxysilanes. Seven alkoxysilanes, namely, 1,2-bis[3-(trimethoxysilyl)propylthio]hexane (T1), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-chloropropane (T2), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-bromopropane (T3), trimethoxy[3-(styrylthio)propyl]silane (T4), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio} hexane (D1), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-chloropropane (D2), and 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-bromopropane (D3), were synthesized by reacting alkynes with 3-mercaptopropylalkoxysilane in the presence of a photoinitiator. The thiol-yne reactions ran neatly in standard glassware under 100 W UV irradiation. The functionalized trialkoxysilanes were obtained in quantitative to near-quantitative yields with high purity. Results showed that the reaction of synthesized T4 only occurred in the first cycle, and vinyl sulfide adduct was formed with two configurations of Z and E. Moreover, the isomerization of T4 from Z to E configurations was induced under UV irradiation. T1 and D1 showed excellent photoluminescence properties. Molecular calculations were also performed to confirm the experimental results. Computational results revealed that all compounds exhibited relatively large HOMO-LUMO band gaps, making them promising candidates as host materials for emitters and hole-electron blocking materials in OLED displays. In addition, T1, T2, and T3 were selected to modify the surface properties of Si (1, 0, 0), which can then be used for further functionalization or the immobilization of polymers or biomolecules.