Intramolecular hydrogen bond-driven conformational preferences in pyridine-containing dibenzamide and dicarboxamide derivatives: evidence from NMR and DFT-based computation

couplings, monitoring the effect of dilution, temperature, and polarity variation on the chemical shifts of HB-involved labile -NH protons, confirmed the existence of intramolecular HBs in the investigated molecules. The experimental findings are further validated by DFT calculations, Boltzmann population distribution and relaxed potential energy surface (PES) scans, Quantum Theory of Atoms in Molecules (QTAIM), non-covalent interaction (NCI), and natural bond orbital (NBO) analyses.