Silanized Aryl Layers through Thiol-yne Photo-click Reaction

Nanometer-scale multilayered coatings were prepared by sequential surface reactions on gold plates. First 4-ethynylphenyl organic layer was electrografted from the parent diazonium tetrafluoroborate salt providing reactive alkynylated gold plate (Au-Y). The latter served for clicking mercaptosilane via a thiol-yne photo-triggered reaction to obtain alkoxysilane-functionalized surface. The trialkoxysilane top groups in turn served as anchor sites for the final sol-gel coating resulting from the surface reaction between aminopropylsilane and tetraethoxysilane (TEOS). It is demonstrated that two coupling agents, namely, aryl diazonium salt and silane, can be coupled using photo-triggered thiol-yne click reaction, resulting in robust multilayered coatings. In addition, the process is versatile in that it offers the possibility to design patterned surfaces. The top sol-gel layer can in turn be reacted with aminosilane, therefore providing a reactive and functional surface that can be used for different applications given the reactivity of amine groups. This approach opens new avenues for photo-triggered click reactions of aryl layers from diazonium salts. It shows that the new class of surface modifiers and coupling agents has much to offer and continues to be renewed for achieving tightly bound, reactive top coatings.