Synthesis, potent anti-TB activity against M. tuberculosis ATTC 27294, crystal structures and complex formation of selected 2-arylidenehydrazinylbenzothiazole derivatives

Alessandra C. Pinheiro, Marcus V. N. de Souza, Maria C. S. Lourenco, Cristiane F. da Costa, Thomas C. Baddeley, John N. Low, Solange M. S. V. Wardell, James L. Wardell*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The synthesis, anti-TB activity, crystal structures and ligand ability of a number of 2-arylidene-benzylidenehydrazinylbenzothiazole derivatives, 1, have been investigated. The compounds 1 were obtained from 2-hydrazinobenzothiazole and substituted benzaldehydes in refluxing methanol in yields, after recrystallisation, of 55-75%. The crystal structure determination of compounds, 1e (aryl = 4-MeOC6H4), 1h (aryl = pyridin-2-yl), if (aryl = 2-HO-5-MeC6H3) revealed amino forms, whereas an imino form was found for if (aryl = 2-HO-4-MeOC6H3). Despite the different tautomeric forms of 1e and 1h, the two compounds have similar cell dimensions and furthermore their intermolecular interactions combine to form similar sub-structures. Pairs of N-H center dot center dot center dot N hydrogen bonds and pi center dot center dot center dot d pi stacking interactions produce dimers in all compound. The compounds with the best anti-mycobacterial activity were found to be 1c (aryl = 2-O2NC6H4), 1d, (aryl = 2-HOC6H4), 1e and 1h, all having superior activities to that of the standard drug, ethambutol. Moreover two of these compounds have the capacity to act as tridentate ligands, namely 1d [a potential ONN chelator] and 1h [a potential NNN chelator]. Compound 1d (HL) acts as a tridentate O,N,N-donor to Cu-(II) in forming the dimeric octahedral complex([(L) (H2O)Cu](O3SCF3]}(2), 3, from Cu-(II) (O3SCF3)(2) in moist MeOH. The monomeric square-pyramidal [(L) (H2O)Cu][O3SCF3], with an axial OS(O-2)CF3 ligand and equatorial H2O ligand, dimerizes through extensive pi center dot center dot center dot pi interactions involving two complete planar L-Cu fragments. The dimers are linked into a three dimensional array by O-H center dot center dot center dot O N-H center dot center dot center dot O hydrogen bonds and by further pi center dot center dot center dot pi interactions. Complex 3, while still very active, has only about 40% of the activity of its ligand against M. tuberculosis ATTC 27294. (C) 2018 Published by Elsevier B.V.

Original languageEnglish
Pages (from-to)655-668
Number of pages14
JournalJournal of Molecular Structure
Early online date26 Oct 2018
Publication statusPublished - 15 Feb 2019


  • 2-Arylidenehydrazinylbenzothiazole
  • derivatives: crystal structure
  • determinations
  • Anti-TB activity
  • Copper complex
  • Imino/amino tautomers
  • 2-Arylidenehydrazinylbenzothiazole derivatives: crystal structure determinations

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