Cyrhetrenylaniline and new organometallic phenylimines derived from 4- and 5-nitrothiophene: Synthesis, characterization, X-Ray structures, electrochemistry and in vitro anti-T. brucei activity

Patricia Toro, Constanza Suazo, Alejandra Acuña, Mauricio Fuentealba, Vania Artigas, Rodrigo Arancibia, Claudio Olea-Azar, Mauricio Moncada, Shane Wilkinson, A. Hugo Klahn

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

A novel series of cyrhetrenyl (3a-4a) and ferrocenyl (3b-4b) Schiff bases were synthesized through a condensation reaction, between the known 4-ferrocenylaniline (2b) or the unreported 4-cyhretrenylaniline (2a) with 4- or 5-nitrothiophenecarboxaldehyde. The structure of 2a and the new Schiff bases have been elucidated using conventional spectroscopic techniques (FT-IR, 1H and 13C NMR), mass spectrometry, and single-crystal X-ray diffraction analysis of compounds 2a, 4a and 3b. Cyclic voltammetry of organometallic phenylimines derived from 5-nitrothiophene showed NO2 group reduction potentials (E1/2 ≈ −0.575 V) that were more anodic than those registered for their 4-nitro analogues (E1/2 ≈ −0.981 V). All organometallic imines were tested against the bloodstream form of Trypanosoma brucei. Evaluation indicated that the most active complexes are the 5-nitrothiophene derivatives, 4a, which were remarkably more active than nifurtimox. In addition, complex 4b resulted in less toxicity to host L6 cells than nifurtimox. The results revealed that the electronic effects of cyrhetrene and ferrocene are not an influential factor in E1/2 and anti-Trypanosoma brucei activity for these new imines, which is probably due to the non-coplanarity of the [(η5-C5H4)-C6H4-N=CH-(C4H2S)] system.

Original languageEnglish
Pages (from-to)13-21
Number of pages9
JournalJournal of Organometallic Chemistry
Volume862
DOIs
StatePublished - 1 May 2018
Externally publishedYes

Keywords

  • 4-nitrothiophenecarboxaldehyde
  • Anti-Trypanosoma brucei activity
  • Cyclic voltammetry
  • Organometallic Schiff bases
  • Phenylimine bridge

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