2-(1H-diazol-2-ylmethylene)indane-1-ones and 2-(1H-diazol-2-ylmethylene)-1H-indene-1,3(2H)-diones: Photoisomerization and hydrogen-bonding-induced association

Mark V. Sigalov, Bagrat A. Shainyan, Nina N. Chipanina, Larisa P. Oznobikhina, Irina V. Sterkhova

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The products of condensation of 2-imidazolyl-, 4-imidazolyl-, 3-pyrazolylcarbaldehydes with indan-1-one 1–3 and 1H-indene-1,3(2H)-dione 4–6 were synthesized. The E-isomers of 1–3 undergo UV-induced isomerization to the Z-isomers stabilized by intramolecular NH⋯O[dbnd]C hydrogen bond with the pyrrolic-type NH group. Theoretical analysis of all isomers, tautomers and rotamers showed that the degree of conjugation between the diazolyl group and the C[dbnd]O group decreases in the order 1 > 2>3. Spectroscopic study of 1–6 performed before and after UV irradiation allowed to conclude on the nature of the associates formed. A remarkably different association of the 2- and 4-imidazolyl derivatives 4 and 5 was revealed by X-ray and confirmed theoretically, leading to the formation of the chelate rings closed by NH⋯O[dbnd]C hydrogen bond in 4 or by N–H … Npyridinic hydrogen bond in 5. Both chelate rings include two bifurcate H-bonds with bifurcation on the carbonyl oxygen and the pyrrolic NH hydrogen.

Original languageEnglish
Article number131755
StatePublished - 1 Jan 2021


  • Diazolylmethyleneindanones and -indenediones
  • Hydrogen bonding
  • IR and UV spectroscopy
  • NMR
  • Photoinduced E→Z-isomerization
  • QTAIM analysis
  • Quantum chemical calculations
  • X-ray structural analysis

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry


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