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A Practical and Efficient Synthesis of Uniform Conjugated Rod‐Like Oligomers
Author(s) -
Hahn Daniel,
Schneider Rebekka V.,
Foitzik Elena,
Meier Michael A. R.
Publication year - 2021
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.202000735
Subject(s) - pentamer , trimer , tetramer , sonogashira coupling , yield (engineering) , chemistry , nuclear magnetic resonance spectroscopy , materials science , proton nmr , mass spectrometry , polymer chemistry , combinatorial chemistry , organic chemistry , dimer , chromatography , palladium , biochemistry , metallurgy , enzyme , catalysis
Abstract Herein, a more practical and efficient synthesis protocol for the preparation of uniform rod‐like oligo(1,4‐phenylene ethynylene)s (OPE)s is presented. Applying an iterative reaction cycle consisting of a decarboxylative coupling reaction and a saponification of an alkynyl carboxylic ester, a uniform pentamer is obtained in ten steps with 14% overall yield. The copper‐free conditions prevent homocoupling until the trimer stage, resulting in a significantly easier work‐up of the products. Homocoupling is observed from the tetramer stage on, but a simple variation of the work‐up procedure also yields the uniform tetramer and pentamer. A thorough comparison with the commonly used and described Sonogashira approach reveals that with the new presented strategy, OPEs can be built in similar overall yield, but easier purification and in a quarter of the time. All oligomers are fully characterized by proton and carbon nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), size‐exclusion chromatography (SEC), and infrared spectroscopy (IR).