Mesoiônicos 1,3,4-tiadiazólio-2-aminidas: síntese, solvatocromismo & citotoxidade

Abstract

Mesoionic compounds are heterocycles with dipolar structure. They have considered interesting because of their diversificating biological activity and other applications like new materiais and colourings. Four news mesoionic compounds of 1,3,4-thiadiazolium-2-aminide class, with p-substituted cinnamoyl group and seven chloridrates of the same class were synthesized. The methodology of the synthesis consisted in the anhidroacylation reaction of thiossemicarbazides with p-substituted cinnamoyl acid chlorides, after that a tratment with base was used. This compounds were characterized by espectroscopic technics, specially NMR 1H and 13C and ultraviolet. The pKa (s) values were determined with spectrophotometric method. A mild acid nature and significant correlationship with dual parameters of substituents, sR, were observed. The solvatochromic properties ofthe synthesized compounds were investigated. New empiric scales of polarity were stablished by a transition energy change in ultraviolet spectro. The ET (BLD) and ET (MIH) scales were correlated with other empiric scales of polarity, where ET (30), ET (26), Z, S, X R, XB and Py were the best correlations showed. Quimiosensibility assays against Ehrlich carcinoma's cells showed significant citotoxic activity for mesoionic compounds and their salts