PEG-400 mediated synthesis, computational, antibacterial and antifungal studies of fluorinated pyrazolines

Abstract

The present study explores a detailed comprehensive study on the computational, antibacterial and antifungal studies of pyrazoline derivatives. Four chalcones and corresponding 5-aryl-3-(4-fluorophenyl)-1-phenyl-4,5-dihydro-1H-pyrazoles were synthesized in PEG-400 and the structure of the pyrazolines were affirmed by IR, 1H NMR, and 13C NMR spectral techniques. The PEG-400 mediated synthesis of pyrazoline derivatives is effective, eco-friendly, and straightforward. The molecular structure, optimized geometrical parameters, UV and vibrational assignments were established by the density functional theory (DFT); the Becke-3-Lee-Yang-Parr (B3LYP) functional with 6-311++G(d,p) basis set. The absorption energies, excitation energy, oscillator strength, and transitions of four pyrazolines were computed using time-dependent density functional theory (TD-DFT) at B3LYP/6-311++G(d,p) level of theory for B3LYP/6-311++G(d,p) optimized geometries. The FMO study affirms that the molecule FPMP has the lowest bandgap with maximum charge transfer. A good correlation between theoretical and experimental UV and vibrational findings was obtained. Various global descriptors like were electronegativity, absolute hardness, global softness, global electrophilicity, chemical potential, and the maximum number of electrons transferred (Nmax) were calculated. The phenyl ring attached to nitrogen is likely to react with electrophiles, as shown in a molecular electrostatic potential surface analysis. The antibacterial screening was performed against two Gram-positive bacterial strains namely S. aureus and B. subtilis and two Gram-negative bacterial strains namely E. coli and P. vulgaris. On the other hand, the antifungal evaluation of the synthesized pyrazoline derivatives was carried out against two fungal strains namely A. niger and C. albicans.