Synthesis, characterization of (E)-3-((2‑hydroxy-5-(thiophen-2-yl)benzylidene)amino)benzonitrile and optimization of its energy by Fuzzy Logic Modelling

• Novel nitrile substituted azomethine compound (3) was successfully synthesized. • FLA and DFT have been used together to optimize the energy of the compound 3 . • PES scan was performed to get the global minimum. • Mamdani type of fuzzy rule model is applied to the optimized structure. • All DFT calculations for 3 has been performed at B3LYP/6–31G(d,p) and 6–311G(d,p) basis set. The title compound (E)-3-((2‑hydroxy-5-(thiophen-2-yl)benzylidene)amino)benzonitrile (3) was prepared with a good yield and experimentally characterized by the UV–Vis, FTIR, 1 H and 13 C NMR spectroscopy. The molecular structure of 3 was optimized with DFT/B3LYP/6–31G(d,p) and 6–311G(d,p) method by using Gaussian 09 software package. Also, using the Mamdani-type fuzzy inference system, DFT calculations of the studied molecule together and fuzzy logic approaching (FLA) have been combined. Thus, the energy structure dependant on two torsional angles SC1(C2C1C19S18) and SC2(C4C5C7N8) of the compound 3 was modelled. Thanks to the optimized energy surface of the molecule, the discrete energy data is made continuous and untested data which are time-consuming to obtain by other methods/experimentation are made computable. Then, to show the consistency of the optimization, a regression analysis was also performed between the results obtained with the DFT and FLA methods, and it was shown that the results were very close to each other at a rate of 98.16%. The theoretical characterization of 3 was carried out using the DFT/B3LYP/6–31G(d,p) and 6–311G(d,p) calculations, and the experimental and theoretical results were discussed extensively. In addition, the molecular electrostatic potential (MEP) surface, the energies of HOMO-LUMO, the atomic charges and natural bond orbital analysis (NBO) for 3 were investigated in detail by using the DFT/B3LYP/6–31G(d,p) and 6–311G(d,p) calculations.