The combinatorial synthesis of oligo(phenylene ethynylene) tetramers, both in solution and on solid support, is described. These products are of interest for molecular electronics applications. An iterative sequence, coupling of aryl halides to alkynes under Sonogashira conditions, was used. Five monomers functionalized with electron-donating or electron-withdrawing groups were synthesized, and used to generate a library of 25 trimers in a solution-phase based process. A library of 24 tetramers was prepared by subsequent protodesilylation and coupling with the alligator clip 4-iodo-1-thioacetylbenzene. The solution-phase based sequence was successfully adapted to a higher yielding directed split-and-pool solid-phase process, with average yields of 78–86% for each step over seven steps. A triazene linker group was used to attach the starting monomer to the polymer beads. At the completion of the solid-phase-based process, traceless cleavage of trimers from the resin was achieved by sonication of the resin in 10% HCl/THF solution. The released products were then poised for the final step in the sequence, attachment of the alligator clip. 相似文献
Poly(2,5-bis[N-methyl-N-hexylamino] phenylene vinylene) (BAM-PPV) has been studied for several decades as an anti-corrosion coating. Although the polymer is readily synthesized via base-promoted radical chain polymerization, BAM-PPV exhibits poor solubility at high-molecular weights (Mw > 100 kDa), which limits its applications. In this work, the molecular weight of BAM-PPV was modulated with nitrobenzene. At nitrobenzene loading as low as 0.9 mol%, the polymerization reaction produced low-molecular weight BAM-PPV (Mw = 5–46 kDa). The polymerization of BAM-PPV was systematically studied via size-exclusion chromatography (SEC), liquid chromatography–mass spectrometry (LC-MS), and 1H NMR spectroscopy, which revealed suppression of the dimer intermediate before chain polymerization. Collectively, this work could expand the practical applications of BAM-PPV for use in optoelectronic devices or corrosion inhibition coatings. 相似文献
Summary: Conjugated poly(p‐phenylene ethynylene) networks with interesting optoelectronic properties were synthesized by the palladium‐catalyzed polycondensation of 2,5‐diiodo‐4‐[(2‐ethylhexyl)oxy]methoxybenzene, and 1,4‐diethynyl‐2,5‐bis‐(octyloxy)benzene, with 1,2,4‐tribromobenzene as cross‐linker. The cross‐linker concentration was varied and materials with different cross‐link densities were prepared. The materials were processed into films by simultaneous polymerization and shaping. An alternative approach is to synthesize these cross‐linked polymers in the form of spherical particles, which can be processed from dispersions.
Schematic representation of the cross‐linking process. 相似文献
A sterically encumbered m‐terphenyl oxacyclophane substituted with two aryl iodide substituents has been prepared as a versatile monomer for the preparation of π‐conjugated polymers. The monomer has been used to prepare a poly(p‐phenylene ethynylene) derivative (P1) incorporating oxacyclophane units as canopies that shield one side of the π‐system from inter‐chain interactions. The photophysical properties of P1 in dilute solution compare well to those of a poly(p‐phenylene ethynylene) derivative (P2) that lacks the canopy. The presence of the steric canopy leads to a diminished inter‐chain interaction in the solid state and enhances the kinetic response of P1 to vapors of nitro‐organics such as TNT, presumably by increasing the permeability of P1 to these analytes over that of P2.
In recent years, water-soluble conjugated polymers have been attained much attention as the optical platform in fluorescent chemical and biological sensors1. In comparison to the small molecule counterparts, conjugated polymers exhibit signal amplificatio… 相似文献
Using diamine as anchoring group, the self-assembled monolayers (SAMs) based on oligo(phenylene ethynylene)s (OPEs) and cruciform OPEs with an extended tetrathiafulvalene (TTF) (OPE3 and OPE3-TTF) were successfully formed on the Au substrate and then utilized in molecular junctions by conductingprobe atomic force microscopy (CP-AFM). 相似文献