Ladderlike oligomers : intramolecular hydrogen bonding, push-pull character, and electron affinity

K. Pieterse, J.A.J.M. Vekemans, H. Kooijman, A.L. Spek, E.W. Meijer

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)


Symmetrical 2,5-bis(2-aminophenyl)pyrazines have been synthesized by application of the Stille coupling strategy. These cotrimers feature three important properties, namely strong intramolecular hydrogen bonding, push-pull character, and high electron affinity. The presence of intramolecular hydrogen bonds has been confirmed by 1H NMR, IR spectroscopy, and single-crystal X-ray diffraction. The hydrogen bond strength can be increased by substituting the amino groups with stronger electron-withdrawing functionalities. Despite the anticipated enhanced -conjugation through planarization, a hypsochromic shift was observed in the UV/Vis spectra, explained by a decrease in push-pull character. The electron affinity of the cotrimers was deduced from the first reduction potentials measured by cyclic voltammetry and is related to the electron-withdrawing character of the amino substituents. The results obtained have been compared with those of the corresponding 4-aminophenyl analogues and show that intramolecular hydrogen bonds can be used to design polymers with enhanced conjugation as well as a high electron affinity.
Original languageEnglish
Pages (from-to)4597-4603
Number of pages7
JournalChemistry : A European Journal
Issue number24
Publication statusPublished - 2000


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