A new photochromic system based on a pyridazinopyrrolo[1,2-b]pyridazine with ultrafast thermal decoloration

Rolf Fromm, Saleh A. Ahmed, Thomas Hartmann, Volker Huch, Aboel A. Abdel-Wahab, Heinz Dürr

Research output: Contribution to journalJournal articlepeer-review

31 Scopus citations

Abstract

The nucleophilic addition of the substituted pyridazines 2a-e to diacetylspirocyclopropene (1) in dry ether solution afforded the dihydroindolizines 3a-e, which undergo ring opening to the betaine 3′a-e after irradation with UV light. Condensation of the diacetyl groups of the dihydroindolizines (DHIs) 3a-e with hydrazine hydrate in a diethyl ether/ethanol mixture gave the new pyridazinopyrrolo[1,2-b]pyridazines 4a-e. Compounds 4a-e showed no photochromism at room temperature or after cooling with liquid nitrogen. However laser flash spectroscopy was successfully used for the determination of both the half-life and absorption maxima of the betaines 4′a-e.

Original languageEnglish
Pages (from-to)4077-4080
Number of pages4
JournalEuropean Journal of Organic Chemistry
Issue number21
DOIs
StatePublished - Nov 2001
Externally publishedYes

Keywords

  • Laser spectroscopy
  • Nitrogen heterocycles
  • Photochromism

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