Synthesis, X-Ray Analysis, Anticancer Activity, Computational, and in Silico Studies of New Thiophene Pyrazole Conjugates

Abstract

A convenient synthesis of two new thiophene-appended pyrazoles, 8a and 8b, from thiophene derivative 3 is reported. The structures of the synthesized compounds were confirmed by infrared, nuclear magnetic resonance, and mass spectroscopy analysis, while compound 8a was further confirmed by single-crystal X-ray diffraction and computational studies. The crystal structure of 8a revealed a nonplanar conformation stabilized by N─H···O hydrogen bonding and a weak C─H···O/N contacts. Hirshfeld surface analysis of 8a showed that H···H contacts dominate the packing, accounting for 52.8%. Density functional theory calculations showed a highest occupied molecular orbital–lowest unoccupied molecular orbital gap of 3.999 eV, indicating a moderate electronic stability with charge transfer ability. The in vitro antitumor activity of the synthesized compounds was evaluated against liver (HepG2), breast (MCF-7), and colorectal (HCT-116) cancer cell lines, using the sulforhodamine B (SRB) assay. Compound 3 showed the highest activity against MCF-7 (IC50 = 2.2 ± 0.3 μg/mL), while the thiophene pyrazole hybrid 8b demonstrates greater activity than 8a against all tested cell lines. In silico evaluation indicated that 8b showed the most balanced safety and drug likeness profile.