A hydrazine-hydroxy-pyran-2-one derivatives as a potential anticancer and antibacterial agent: synthesis, spectroscopic, SC-XRD, DFT/TD-DFT, Hirshfeld surface analysis, in silico molecular docking and nonlinear optical responses studies

This study presents the synthesis and thorough characterisation of a hydrazine-hydroxy-pyran-2-one derivative referred to as compound (<b>L₁</b>: 3, 3′- [(1<i>E</i>.2E)-hydrazine-1, 2-diylidene-dieth-1-yl-1-ylidene] bis(4-hydroxy-6-methyl-2<i>H</i>-pyran-2-one). Structural elucidation using UV-vis, FT-IR and single crystal X-ray diffraction (SC-XRD) confirmed tautomeric forms of <b>L₁</b>. The SC-XRD analysis revealed a bi-zwitterionic form (<b>BZL₁</b>), stabilised by the intramolecular proton transfer between two enol units and azine tautomerism. The planar molecular structure, supported by XRD, DFT and Hirshfeld surface analysis, showed charge-assisted hydrogen bonds [N⁺−H…O⁻] forming S(6) ring motifs. Crystals were stabilised by C-H…O hydrogen bonds and π-π stacking, analysed through Hirshfeld surfaces and 2D fingerprint plots. Compound <b>L₂</b>: 3-[(1<i>E</i>)-1-(9<i>H</i>-fluoren-9-ylidenehydrazinylidene)ethyl]-4-hydroxy-6-methyl-2<i>H</i>-pyran-2-one), is illustrated in this paper to compare two derivatives of dehydroacetic acid (DHA) and to enrich this study. Molecular docking revealed binding affinities of hybrid compounds with target proteins. DFT and TD-DFT analyses examined structural, electronic and optical properties, aligning well with experimental data. <b>BZL₁</b> exhibited higher electronic hardness (3.632 eV) than <b>L₂</b> (3.506 eV). Variations in α, Δα and ρ values were observed, with <b>L₁</b> showing stronger γ(0; 0, 0, 0) and γ(−ω; ω, 0, 0) while <b>L₂</b> excelled in γ(−2ω; ω, ω, 0). Consequently, these results highlight the potential of these compounds as promising candidates for use in third-order nonlinear optical applications.