Covalently Attached Monolayers on Hydrogen‐Terminated Si(100): Extremely Mild Attachment by Visible Light

Wet chemical routes to the assembly of organic monolayers on silicon surfaces via the formation of Si–C bonds: surface preparation, passivation and functionalization

“…Therefore, based on FTIR spectral data and quantum mechanical calculations, the formation of surface heterocycles (either 1,1-or 1,2-bridged products) involving bridged silicon surface atoms cannot be disregarded on Si(100)-H. 125 Interestingly, analogous discrepancies for the immobilization of 1-alkynes are found in the porous silicon literature. 28,84,183 Whether the different conclusions of Sun et al 126,166 and Cerofolini and co-workers 180 with regards to the hydrosilylation mechanism are due to either the different unsaturated hydrocarbons used (e.g. different lengths), or due to differences in reaction conditions, surface preparation protocols or characterization techniques, is not clear at present and will require further work.…”

“…10 À7 ) probability of forming a nucleation site. Since the homolytic dissociation of surface Si-H (and Si-Si) cannot be operative under white light illumination 126 and given the low efficiency of the initiation process, plausible alternative mechanisms include light-induced radical formation from impurities in solution 119 and a hole-related mechanism (Fig. 7) favouring the reaction on illuminated n-type substrates, as compared to p-type, as proposed by Sun et al 126 Alternatively, as in the case of 1-alkynes thermally reacted onto p-type H-Si(100)-(1 Â 1) samples, 177 a concerted hydrosilylation mechanism has been argued for by Cerofolini and colleagues [178][179][180][181] (Fig.…”

Photochemical Attachment of Organic Monolayers onto H-Terminated Si(111): Radical Chain Propagation Observed via STM Studies

“…4 Recently, a mild method compatible with the fragility of biomolecules and which relies on the general procedure depicted in Figure 1was reported by two of us. 5 In this scheme a simple fluoride-induced etching step is followed by irradiation of a mesitylene solution of a ω-functionalized 1-alkene or 1-alkyne with visible light (e.g., 447 nm). By using this procedure it has, for example, been possible to attach labile sialic acid derivates onto H-Si(100).…”

“…5,7,8 However, given the low efficiency of the initiation process it is difficult to completely rule out the role of light-induced generation of radical species from impurities in solution (even given the highly pure reactants used here). Whatever the initiation event, it must involve the eventual formation of a carbon-centered radical on the attached alkene.…”

GM3, GM2 and GM1 mimics designed for biosensing: chemoenzymatic synthesis, target affinities and 900MHz NMR analysis

“…The specific interactions between such GM1, GM2 and GM3 ganglioside analogues and GBS-related antibodies open the way for biosensing as a diagnostic tool for GBS, for example, via semiconductor surfaces 30 that have been covalently modified with specific oligosaccharides. 31,32 For the preparation of such monolayers, we developed an extremely mild photochemical method (visible light, room temperature), 33,34 which allows for the attachment of labile bio(macro)molecules such as saccharides, DNA and proteins, if their synthesis with appropriate linkers would be feasible. Linkers of choice for such attachments are x-alkenyl or x-alkynyl tails with the length of at least 10 carbon atoms.…”