Molecules (Nov 2022)

4-(Aryl)-Benzo[4,5]imidazo[1,2-<i>a</i>]pyrimidine-3-Carbonitrile-Based Fluorophores: Povarov Reaction-Based Synthesis, Photophysical Studies, and DFT Calculations

  • Victor V. Fedotov,
  • Maria I. Valieva,
  • Olga S. Taniya,
  • Semen V. Aminov,
  • Mikhail A. Kharitonov,
  • Alexander S. Novikov,
  • Dmitry S. Kopchuk,
  • Pavel A. Slepukhin,
  • Grigory V. Zyryanov,
  • Evgeny N. Ulomsky,
  • Vladimir L. Rusinov,
  • Valery N. Charushin

DOI
https://doi.org/10.3390/molecules27228029
Journal volume & issue
Vol. 27, no. 22
p. 8029

Abstract

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A series of novel 4-(aryl)-benzo[4,5]imidazo[1,2-a]pyrimidine-3-carbonitriles were obtained through the Povarov (aza-Diels–Alder) and oxidation reactions, starting from benzimidazole-2-arylimines. Based on the literature data and X-ray diffraction analysis, it was discovered that during the Povarov reaction, [1,3] sigmatropic rearrangement leading to dihydrobenzimidazo[1,2-a]pyrimidines took place. The structures of all the obtained compounds were confirmed based on the data from 1H- and 13C-NMR spectroscopy, IR spectroscopy, and elemental analysis. For all the obtained compounds, their photophysical properties were studied. In all the cases, a positive emission solvatochromism with Stokes shifts from 120 to 180 nm was recorded. Aggregation-Induced Emission (AIE) has been illustrated for compound 6c using different water fractions (fw) in THF. The compounds 6c and 6f demonstrated changes in emission maxima or/and intensities after mechanical stimulation.

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