Synthesis, spectral characterization and DFT analysis for the validation of 2, 6 diaryl -piperidin-4-ones as potential sunscreens and UV filters

Synthesis, vibrational spectra, DFT calculations, Hirshfeld surface analysis and molecular docking study of 3-chloro-3-methyl-2,6-diphenylpiperidin-4-one

A newly synthesized molecular complex 3-chloro-3-methyl-2,6-diphenylpiperidin-4-one [CMDP] crystallizes in the triclinic space group P1. The piperidin-4-one ring exhibits a distorted chair conformation with the puckering parameters Q = 0.559 (3) Å, θ = 173.3 (3°) and φ = 180 (2°). The methyl substituent on the third position of the piperidine ring takes up a syn-periplanar positioning although the chloro substituent takes up an anti-clinical positioning with dihedral angle: Cl1-C2-C1-O1 = 113.3 (2°) due to the repulsion from an adjacent oxygen atom. The optimized molecular geometry and fundamental vibrational frequencies of the CMDP compounds are interpreted with the help of normal coordinate force field calculations based on DFT method B3LYP/6-31+G (d,p) level basis set. The HOMO-LUMO energy gap of the molecule is 5.4194 eV. The hardness value (η) of the CMDP molecule is 2.7097 eV. Hirshfeld surface analysis and fingerprint plots are supportive for determining the molecular shape and visually analyzing the intermolecular interactions in the crystal structure. The Hirshfeld surfaces like d_i,d_e,d_norm, shape index and curvedness of C₁₈H₁₈NOCl were pictured and discussed. The various levels of electronic transitions have been predicted by Time-Dependent Density Functional Theory (TD-DFT) calculations and compared with the recorded absorption spectrum. Molecular docking study was performed and reported for the synthesized compound against 4ey7 protein.