Covalent Layer‐by‐Layer Assembly of Redox Active Molecular Multilayers on Silicon (100) by Photochemical Thiol‐Ene Chemistry

Abstract

The fabrication of thin organic films covalently grafted onto silicon substrates is of significant interest, as they are expected to give access to a broad range of new materials for integration into microelectronic applications. Covalent layer-by-layer (LbL) assembly offers a high degree of freedom when designing such thin films. In this work an approach for the preparation of covalent redox active molecular multilayers on silicon (100) surfaces is presented using a highly branched decaallylferrocene and thiol-ene click chemistry. The multilayers are analyzed by ellipsometry, X-ray photoelectron sprectroscopy, and cyclic voltammetry. The results indicate that the multilayer growth is linear for at least sixteen layers and the density of ferrocenes per layer is in the range of 6 × 10⁻¹¹ mol cm⁻². Moreover, this method for LbL assembly is extended to surfaces which have been locally passivated by microcontact printing. By atomic force microscopy measurements it is possible to show that the covalent LbL deposition proceeds exclusively in the nonpassivated areas.

Phenylboronic Acid-Functionalized Layer-by-Layer Assemblies for Biomedical Applications

“…The PBA-Fc copolymer and PVA-modified GOx are spin-coated in a layer-by-layer fashion on the electrode to form a thin film. The redox current of the sensors originating from Fc moiety increases with increasing numbers of LbL layers, as in the case of other Fc-containing LbL films [70,71]. The output current of the sensors depends on the number of GOx layers, confirming the effective electron transfer between GOx and the Au electrode mediated by Fc residues.…”

Metal‐Free Click Chemistry Reactions on Surfaces

“…Ravoo and co‐workers have also developed interesting silicon surface functionalization approaches based on thiol‐ene reactions . In 2012, they reported the covalent attachment of redox‐active molecular multilayers onto silicon containing a highly branched decaallylferrocene, which also acted as crosslinker . For that, they treated hydrogen‐terminated Si wafers with 1,11‐dodecadiene, and upon subsequent reaction with 1,4‐butanedithiol by TEC chemistry, this yielded a thiol‐terminated surface on which the decaallylferrocene was covalently attached by another TEC reaction.…”

Combining the incompatible: Block copolymers consecutively displaying activated esters and amines and their use as protein-repellent surface modifiers with multivalent biorecognition

“…The advent of modular ligation based on orthogonal and highly efficient chemical reactions has undoubtedly revolutionized the field of macromolecular engineering. [1][2][3][4] Intense effort has been focused on expanding the types of reactions, starting from the classical Cu(I)-catalyzed Huisgen cycloaddition of alkynes and azides, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] to thiol-ene chemistry, [22][23][24][25][26][27][28][29][30][31] activated esters, [32][33][34][35][36][37][38][39][40] oxime-click, [41][42][43] Michael addition [44][45][46][47] and hetero Diels-Alder reactions. [48]…”