Formation of hexagonal and cubic fluorescent periodic mesoporous organosilicas in the channels of anodic alumina membranes

Abstract

The synthesis of periodic mesoporous organosilicas (PMOs) in the confinement of porous anodic alumina membranes (AAMs) was successfully achieved through a modified evaporation-induced self-assembly (EISA) process. 1,3,5-Tris(4-triethoxysilylstyryl)benzene, (a three-armed oligo(phenylenevinylene) organosilane compound, abbr. 3a-OPV), the precursor of the first reported charge-conducting PMO, was used as an organosilica source. Triblock-copolymers Pluronic F127 (EO 106 PO 70 EO 106 ) or F108 (EO 132 PO 50 EO 132 ) were used as structure directing agents. The block-copolymer F127 led to a 2D-hexagonal circular mesostructure within the AAM channels and the block copolymer Pluronic F108 resulted in a mesophase with a body-centered cubic (Im 3m) structure. Compared to the previously reported 3a-OPV-PMO film, the resulting hierarchical PMO/AAM systems have improved features, that is, the synthesized PMOs have a pore size of around 10 nm and the compounds are found to be stable against thermal treatment at temperatures of up to 200 C and they are also stable in the electron beam of the electron microscope. Additionally, both of the resulting hierarchical mesoporous composites show fluorescence in the visible region due to the strongly interacting phenylenevinylene chromophores in the PMO frameworks.

Cyclisations Catalysed by Bismuth(III) Triflate

“…A diastereoselective intramolecular Lewis‐acid‐catalysed aza‐Friedel–Crafts cyclisation starting from enantioenriched ( R ) ‐N‐tert ‐butylsulfinamide was developed . It is worth noting that several metal triflates [In(OTf) 3 , Cu(OTf) 2 , Zn(OTf) 2 , Sc(OTf) 3 , Mg(OTf) 2 , Yb(OTf) 3 ] as well as some other Lewis acids were able to catalyse the reaction but with lower yields than Bi(OTf) 3 .…”

Periodic Mesoporous Organosilica Nanoparticles with Controlled Morphologies and High Drug/Dye Loadings for Multicargo Delivery in Cancer Cells

“…Periodic mesoporous organosilica (PMO) materials obtained from organically bridged silanes without an additional silica source such as tetraethoxysilane have been extensively studied in the past fifteen years for their unique composite framework . The structure of bridged silsesquioxane (O 1.5 Si−R−SiO 1.5 with organic R groups) forming the pore interior of organically bridged PMO materials dramatically modifies their surface chemistry when compared to mesoporous silica and organosilica .…”

A Zinc Phthalocyanine Based Periodic Mesoporous Organosilica Exhibiting Charge Transfer to Fullerenes

“…Using E(Fc/Fc + ) = À4.84 eV (Fc = ferrocene) and the relation E LUMO = E HOMO ÀE g,opt , with E HOMO and E LUMO being the energy of the HOMO and LUMO and E g,opt being the optical band gap, we obtain the frontier orbital energies of À5.50 and À3.65 eV (Figure 3c and Figure S4 in the Supporting Information). Compared to [6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) both HOMO and LUMO are around 200 meV higher in energy. We therefore anticipate the formation of a type II junction at the interface between these materials, which should provide enough energy offset for separation of photogenerated charge carriers.…”

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Periodic mesoporous organosilica (PMO) materials offer a strategy to position molecular semiconductors within a highly defined, porous network. [5] In particular, the incorporation of building blocks with conjugated p-systems led to photoactive frameworks, such as fluorescent PMOs [6] or light harvesting frameworks that are capable of energy transfer [7] and charge transfer [8] to molecules inside their porous channels. The exceptional degree of order achieved with this PMO enabled us to create thin films consisting of a single porous domain throughout their entire thickness, thus providing maximal accessibility for subsequent incorporation of a complementary phase.

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“…The combination of functional organic building blocks and inorganic cross-linking parts renders PMOs a highly versatile platform for fundamental research and potential applications as functionalized scaffold materials in catalysis, [2] sensing applications [3] and optoelectronics. [5] In particular, the incorporation of building blocks with conjugated p-systems led to photoactive frameworks, such as fluorescent PMOs [6] or light harvesting frameworks that are capable of energy transfer [7] and charge transfer [8] to molecules inside their porous channels. [5] In particular, the incorporation of building blocks with conjugated p-systems led to photoactive frameworks, such as fluorescent PMOs [6] or light harvesting frameworks that are capable of energy transfer [7] and charge transfer [8] to molecules inside their porous channels.…”