Pyrazole-Thiopyrimidine Disazo Dyes: Synthesis, Solvatochromic Properties, and Biological Activities

Abstract

This study reports the synthesis, characterization, solvatochromic properties, and biological activities of novel disazo dyes (ppt1-ppt13) containing pyrazole and thiopyrimidine moieties. The target compounds were synthesized through a three-step process involving diazotization, coupling, and cyclization reactions. Comprehensive spectroscopic analyses, including NMR, IR, and mass spectrometry, unequivocally confirmed the structures of the disazo dyes. The obtained data provided valuable insights into their structure-activity relationships, establishing a strong basis for future research. A detailed investigation was conducted to assess the solvatochromic behavior of the dyes in various solvents and the tautomeric equilibrium between azo and hydrazo forms under different acid-base conditions. UV-Vis spectral analysis revealed a pH-dependent tautomeric shift, which aligns with the heterocyclic nature of the dyes. Given their unique structural and biochemical properties, these dyes exhibit significant potential for applications in biological and clinical research. To further evaluate their bioactivity, the dyes were tested for anticancer and antifungal activities against a human breast cancer cell line and the opportunistic yeast Saccharomyces cerevisiae, respectively. Among the synthesized compounds, ppt6 exhibited the highest anticancer activity, while ppt12 displayed the most potent antifungal efficacy. These findings suggest that the synthesized dyes, beyond their coloring capabilities, hold promise as candidate molecules for targeting diverse biological systems.