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X-ray Structure of Eleven New N,N′-Substituted Guanidines: Effect of Substituents on Tautomer Structure in the Solid State

Abstract

Guanidine-containing molecules are an interesting class of compounds within both medicinal and material sciences. Having knowledge of their tautomerism is key in designing guanidines that interact with biological and chemical receptors. However, there are limited data on the solid-phase structure of N,N′-substituted guanidines. Thus, eleven guanidines bearing a 4,6-dimethylpyrimidyl at one end and substituents of varying sizes and electronic properties at the other side, were synthesised, crystallised, and analysed by X-ray crystallography. Calculations of isolated molecules of tautomer energies and bond lengths were performed for comparison. One class of guanidines crystallised as a cis–trans tautomer with the shorter bond directed towards the pyrimidyl unit. When more electron-deficient aniline substituents were inserted, the crystallised tautomer changed to a cis–cis form where the shorter bond was directed towards the aniline. The switch in the tautomer structure is concluded to be due to both the electronic properties of the substituents and the intermolecular hydrogen bonding in the crystal lattice.
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Category

Academic article

Language

English

Author(s)

  • Vijayaragavan Elumalai
  • Václav Eigner
  • Nicholas Alexander Janjua
  • Per-Olof Harald Åstrand
  • Torkild Visnes
  • Eirik Sundby
  • Bård Helge Hoff

Affiliation

  • SINTEF Industry / Biotechnology and Nanomedicine
  • University of Chemistry and Technology Prague
  • Norwegian University of Science and Technology

Year

2024

Published in

Crystals

Volume

14

Issue

10

View this publication at Norwegian Research Information Repository