Directional Materials—Nanoporous Organosilica Monoliths with Multiple Gradients Prepared Using Click Chemistry

Abstract

The existence of more than one functional entity is fundamental for materials, which are desired of fulfilling complementary or succeeding tasks. Whereas it is feasible to make materials with a homogeneous distribution of two different, functional groups, cases are extremely rare exhibiting a smooth transition from one property to the next along a defined distance. We present a new approach leading to high-surface area solids with functional gradients at the microstructural level. Periodically ordered mesoporous organosilicas (PMOs) and aerogel-like monolithic bodies with a maximum density of azide groups were prepared from a novel sol-gel precursor. The controlled and fast conversion of the azide into numerous functions by click chemistry is the prerequisite for the implementation of manifold gradient profiles. Herein we discuss materials with chemical, optical and structural gradients, which are interesting for all applications requiring directionality, for example, chromatography.

Stimuli‐Responsive Particle‐Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry

“…The alkyne‐containing shell was prepared by a sol‐gel process with a novel, phenylacetylene‐bridged silsesquioxane precursor ( 4 ) shown in Scheme (see also experimental section in the Supporting Information). We start from the phenylbromide‐bridged sol‐gel precursor ( 1 ), which can be transformed to multiple other groups exploiting the full potential of aromatic substitution chemistry . Here, the bromide is substituted by a trimethylsilyl‐protected acetylene ( 2 ) catalyzed by copper(I) iodide/ 1,1′‐bis(diphenylphosphino)ferrocenedichloropalladium(II) .…”

Functional Gradient Inverse Opal Carbon Monoliths with Directional and Multinary Porosity

“…On FGMs with a gradient in pore‐size, the number of examples is extremely small. In 2015 our group presented macroporous organosilica aerogels having gradient porosity, but without showing any application . A nice paper demonstrating the benefits of a gradient pore structure in the solid‐oxide fuel cell was published by Brandon and Brett in 2006 .…”

Functionalisation and stabilisation of polymeric arsenical nanoparticles prepared by sequential reductive and radical cross-linking

“…The purified products were isolated by lyophilisation. 25 Rhodamine B (1 eq), DCC (1.5 eq), DMAP (0.2 eq) were dissolved in anhydrous DCM (50 ml) and stirred for 30 min. Propargyl alcohol (1.5 eq) was added and stirred at room temperature for 16 h. The crude product was purified by flash column in 1% methanol in DCM, the resulting product fractions combined and the solvent removed in vacuo to yield iridescent black crystals (57% yield).…”