Two-steps functionalization process to extend the novel in situ porous silicon formation-functionalization method

Recently, we have presented a novel in situ simultaneous formation-functionalization (FORFUN) method of porous silicon (PS) layers in which the molecules to be chemisorbed are present in the HF ethanoic solution used for the electrochemical preparation of the PS. In this work we demonstrate that is possible to extend this method to a wider group of organic molecules, in principle even to molecules not compatible with the preparation solution. First a PS single layer functionalized with methyl-6-heptynoate was prepared by the FORFUN method (I step) and then, after a second ex situ chemical process (II step), we obtained the correspondent tertiary alcohol bonded to the surface, as proved by the IR reflection spectra. This two-steps process maintains all the features of the FORFUN method: simplicity, effectiveness and the possibility of confining the chemisorbed species in selected layers in a PS stack ("spatially selective functionalization"). These findings can be relevant for many applications based on PS systems and devices.