Synthesis, crystal structure at 100 K, Hirshfeld surface analysis, DFT calculations, antioxidant evaluation and...

N,N'-Diformohydrazide was synthesized in 89% yield from hydrazine hydrate and formic acid and characterized by single-crystal X-ray diffraction at 100 K. The compound crystallizes in the monoclinic space group P2₁/n. The molecule is planar, and the crystal packing is dominated by N-H···O and C-H···O hydrogen bonds that build corrugated two-dimensional sheets, with H···O contacts identified as the major contributor in Hirshfeld surface analysis. DFT calculations at the ωB97X-D/6-311 + + G(d, p) level reveal a large HOMO-LUMO gap and a high ionization potential, consistent with an electronically stable, hard molecule. NBO analysis identifies a strong nitrogen lone-pair → C =O π* delocalization that accounts for the resonance-assisted character of the hydrazide linkage. MESP, atomic-charge, Fukui, and QTAIM analyses converge on the carbonyl oxygens as the principal hydrogen-bond acceptors and the N-H protons as the principal donors. DPPH, CUPRAC, ABTS, and superoxide assays show only weak radical-scavenging activity relative to BHA and BHT, in line with the predicted electronic stability. Molecular docking against Helicobacter pylori protein targets returned weak-to-moderate binding scores (best score - 4.8 kcal/mol) and is reported as a preliminary in silico screen.