8-Aminoquinoline derived two Schiff base platforms: Synthesis, characterization, DFT insights, corrosion inhibitor, molecular docking, and pH-dependent antibacterial study

Abstract

The current research divulges the synthesis of two new Schiff base (SB) (<b>L</b> ^<b>NAPH</b> /<b>L</b> ^<b>O-VAN</b> ) derived from 8-aminoquinoline (8-AMQ) in the presence of 2-hydroxy naphthaldehyde (NAPH) and ortho-vanillin (O-VAN) in CH₃OH solvent. They are structurally characterized by spectroscopic methods (IR/Raman/UV-vis/DRS/NMR) and SEM-EDX. SB compounds have a biologically active avenue of azomethine/imine group (H-C=N) that can donate N e's to M^{n +} ions, showing coordinating flexibility. The -OH and imine (H-C=N) groups are stable in air, light, and alkalis but undergo acidic environments hydrolysis, separating -NH₂ and carbonyl compounds. Moreover, buffer solutions with a pH range of 4-6 release aldehyde. Molecular electrostatic potential (MEP), Frontier molecular orbitals (FMO), Fukui function, and Non-linear optical (NLO) were conducted to elucidate SBs chemical potency, optoelectronic significance, and corrosion inhibitor. Accordingly, the calculated ΔE of FMO for <b>L</b> ^<b>NAPH</b> and <b>L</b> ^<b>O-VAN</b> is 3.82 and 4.08 eV, ensuring potent biological function. DFT supported the experimental and theoretical IR spectral correlation to enrich better structural insights. NLO-based polarizability (α) and hyperpolarizability (β) factors successfully explore the potential optoelectronic significance. Molecular docking experiments were simulated against DNA, anti-COVID-19, and <i>E. coli</i>. The potential microbiological activity was screened against the bacterial strains <i>E. coli</i>, Klebsiella, Bacillus, and Pseudomonas sp. based on zone of inhibition and MIC values. These experiments also explored the fact that <b>L</b> ^<b>NAPH</b> and <b>L</b> ^<b>O-VAN</b> discourage microbial cell biofilms and corrosion. We extensively covered the as-prepared compounds' pH-dependent bacterial effects.