Photoinduced self-assembly of carboxylic acid-terminated lamellar silsesquioxane: highly functional films for attaching and patterning amino-based ligands

Abstract

International audienceRecently, long n-alkyltrimethoxysilanes (H3C(CH2)nSi(OCH3)3) have proven to self-assemble into mesoscopically ordered passive lamellar films through an efficient solvent-free photoacid-catalysed sol-gel process. By using an analogue precursor architecture presenting terminal ester group (H3COC(O)(CH2)10Si(OCH3)3), both functional and tuneable nanostructured organosilica films were synthesized, while keeping all processing advantages of light-induced self-assembly. The subsequent attachment of a fluorescent amino-based ligand (Safranin O) was performed using a two-step procedure. The ester end groups were first hydrolysed in reactive carboxylic using standard methods, and activated with an amino ligand to form amide bonds. Hydrolysis and ligand coupling were assessed through infrared and solid-state 1 H NMR spectroscopy. Direct patterning of the fluorescent ligand-functionalized silsesquioxane film was performed by exposure to deep UV under a mask to cause the local degradation of the dye. The resultant photopatterned film was detected using fluorescence microscopy. This UV method could represent an effective and general approach for attaching and patterning amino-based ligands, with less restriction on substrate and surface preparation than self-assembled monolayers

Photoinduced nanostructured organosilica hybrids

“…This approach leads to high degree of condensation of the siloxane network without any thermal treatment and affords the possibility of achieving thin and homogeneous films. This method has already opened opportunities in COOH‐functionalized lamellar organosilica with long‐range molecular ordering and uniform or photopatterning of self‐assembled alkylsilane multilayers . We foresee that the expansion of this approach will be driven by the ability to self‐assemble a broader range of organosilanes with less structural constraints and less efforts on chemical design.…”

Ordering minimalist bridged polysilsesquioxane films under visible LED light irradiation

“…Recently, our group introduced a different photochemical route to synthesize highly ordered SQs (18)(19)(20)(21). In this approach, an organosilane-based film is irradiated in bulk in the presence of Brönsted superacids generated in situ by the UV-decomposition of a photoacid generator (PAG) based on diaryliodonium (Ph 2 I + X -) or triarylsulfonium (Ph 3 S + X -) salts.…”