Spectroscopic, molecular docking and quantum computational studies of 2,4-dinitrophenyl hydrazine

• Quantum Computational study for 2,4-dinitrophenyl hydrazine • Studied NMR, UV-Vis, HOMO-LUMO, NLO. • Better protein binding than Paracetamol. • MD shows stable complex for 100 ns. Density functional theory (DFT) optimization studies show that the strong electronegativity difference between N and H leads to N-H bond contraction to approximately 1.01-1.02 Å in 2,4-dinitrophenyl hydrazine (2,4-DNPH), closely matching experimental X-ray values. The gauge-independent atomic orbital (GIAO) approach in conjunction with DFT was employed to calculate the chemical shifts for 13 C and 1 H NMR in chloroform solvent. Time-dependent DFT (TD-DFT) calculations were used to calculate the UV-Vis spectrum in both the gas and methanol phases. The analyses comprised frontier molecular orbital (HOMO-LUMO) energies, molecular electrostatic potential (MEP), electron localization function (ELF), Fukui function reactivity indices, nonlinear optical (NLO) properties and donor-acceptor interactions as demonstrated through natural bond orbital (NBO) analyses. Intermolecular interactions within the crystal structure were elucidated by Hirshfeld surface analysis and fingerprint plots; thermodynamic properties (energy, heat capacity, entropy) analyzed over the temperatures of 100-600 K. A comparative molecular docking analysis indicated that 2,4-DNPH has a better binding affinity (-7.2 kcal/mol) to oxidoreductase proteins than Paracetamol (-6.7 kcal/mol) suggesting potential analgesic and antipyretic activity. Molecular dynamics simulations (MDS) over 100 ns of the 2,4-DNPH-protein complex (PDB ID: 4CRT ) demonstrated stable ligand-protein interactions over 100 ns, with average RMSD of approximately 0.4 nm and sustained hydrogen bonding.