Solid-Phase Synthesis of Oligo(p-benzamide) Foldamers

[reaction: see text] A coupling protocol has been developed which allows the synthesis of oligo(p-benzamide)s on solid support. Aromatic carboxylic acids are activated in situ with thionyl chloride and used to acylate secondary aromatic amines. N-p-Methoxy benzyl (PMB) as well as N-hexyl protected monomers were investigated. Heterosequences of both monomers were synthesized. Such nanoscale objects are important building blocks for supramolecular chemistry.

Large area perovskite light-emitting diodes by gas-assisted crystallization:

Halide perovskites have been gaining considerable attention recently for use in light-emitting applications, due to their bandgap tunability, color purity and low cost fabrication methods. However, current fabrication techniques limit the processing to small-area devices. Here, we show that a facile N 2 gas-quenching technique can be used to make methylammonium lead bromide-based perovskite light-emitting diodes (PeLEDs) with a peak luminance of 6600 cd m −2 and a current efficiency of 7.0 cd A −1 . We use this strategy to upscale PeLEDs to large-area substrates (230 cm 2 ) by developing a protocol for slot-die coating combined with gas-quenching. The resulting large area devices (9 device…

Soluble oligoaramide precursors--a novel class of building blocks for rod-coil architectures.

A new synthetic route is described that allows the reversible conversion of the inherently insoluble oligo-p-benzamides into soluble materials through the formation of imidoyl chlorides. Syntheses of the corresponding dimer, trimer, and tetramer are reported; these compounds can easily be purified by crystallization and are accessible on the multigram scale. Structural proof was obtained by single-crystal X-ray structures of the trimer and tetramer precursors. They can be selectively functionalized into amides or esters at the terminal carboxylic acid group followed by hydrolysis of the imidoyl chlorides to the parent amides. This new class of compounds gives access to strongly aggregating …

Efficient Perovskite Light-Emitting Diodes: Effect of Composition, Morphology, and Transport Layers

Organic-inorganic metal halide perovskites are emerging as novel materials for light-emitting applications due to their high color purity, band gap tunability, straightforward synthesis, and inexpensive precursors. In this work, we improve the performance of three-dimensional perovskite light-emitting diodes (PeLEDs) by tuning the emissive layer composition and thickness and by using small-molecule transport layers. Additionally, we correlate PeLED efficiencies to the perovskite structure and morphology. The results show that the PeLEDs containing perovskites with an excess of methylammonium bromide (MABr) to lead bromide (PbBr2) in a 2:1 ratio and a layer thickness of 80 nm have the highes…

Hockey-Puck micelles from oligo(p-benzamide)-b-PEG rod-coil block copolymers.

Hockeypuck-Micellen aus Oligo(p-benzamid)-b-PEG-Stab-Knäuel-Blockcopolymeren

Rod-Length Dependent Aggregation in a Series of Oligo(p-benzamide)-Block-Poly(ethylene glycol) Rod-Coil Copolymers

The synthesis of a series of rod-coil diblock copolymers with flexible poly(ethylene oxide) chains (M n = 5 000 g mol -1 ) and rod blocks consisting of monodisperse oligo(p-benzamide)s is described. The formation of defined supramolecular aggregates in solution as well as the solid state has been analyzed. The length of the oligo(p-benzamide)s has been systematically varied from n = 1 to 7 units. The influence of n on aggregation in chloroform and aqueous solution was investigated by GPC as well as UV-vis spectroscopy. A critical aggregation length was found for chloroform (n = 5) and water (n = 4), below which no aggregation is observed under otherwise identical experimental conditions. Ag…