Thione or Thiol: Sructural Confirmation of (E)-2-(1-(4-cyanophenyl)ethylidene)-N-(2-fluoro-4-sulfamoylphenyl)hydrazine-1-Carbothioamide and Carbonic Anhydrase Inhibition Studies

Abstract

Thiosemicarbazones are Schiff bases formed by condensing an aldehyde or ketone with thiosemicarbazide derivatives. TSCs exhibit various biological activities and act as precursors for key scaffolds, with keto-enol tautomerism commonly resulting in thione or thiol forms. This study focuses on synthesizing and confirming the structure of compound 1, (E)-2-(1-(4-cyanophenyl)ethylidene)-N-(2-fluoro-4-sulfamoylphenyl)hydrazine-1-carbothioamide, through a condensation reaction in methanol. Both theoretical and experimental IR and X-ray studies confirm the presence of the thione form and E isomerism. Compound 1 showed inhibitory activity against four human carbonic anhydrase isoforms (hCA I, II, IX, XII) with Ki values of 36.0, 5.7, 29.5, and 7.0 nM, respectively.