Comparative Green and Conventional Synthesis of 2-Hydroxy-1-Naphthaldehyde Based Barbiturates and Their DFT Study

2-Hydroxy-1-naphthaldehyde based barbiturates were synthesized through an eco-friendly greener approach, by reaction of 2-hydroxynaphthalene-1-carbaldehyde with three different barbituric acid derivatives in presence of natural, biodegradable and biocompatible green catalyst chitosan-SO3H. The use of solvent-free reaction in presence of functionalized chitosan for the synthesis of barbituric acid derivatives makes the present protocol as green and eco-friendly. A comparative study of conventional as well as solvent-free methods highlights the advantages, such as admirable yield, reduced reaction time with eviction of environmentally hazardous solvents, which leads to sustainability. The chemical structures of compounds were characterized by spectral techniques like IR, 1H NMR, 13C NMR and mass spectrometry. Additionally, computational studies of synthesized compounds were performed using density functional theory (DFT) at M06 level and 6-311 G (d,p) basis set to elucidate the electronic structures, and counter check the experimental findings. Overall, DFT findings at M06/6-311G (d,p) level show good agreement with the experimental data which confirms the purity of entitled compounds. Natural bond orbital (NBO) analysis and non-linear optical (NLO) properties were explored at the M06-/6-311G (d,p) level of theory. NBO analysis confirmed that hyper conjugative interactions are responsible for the stability of compounds. The energy gaps in compounds 5, 6 and 7 were found as 3.822, 3.815 and 3.643 eV, respectively. Furthermore, the global reactivity parameters were calculated using the FMOs energies which indicate that 5–7 hold more donating capability and stability. NLO findings confirmed that 5–7 have superior properties as compared to prototype standard compounds which unveiled their potential applications for optoelectronic technology.