Photophysical and theoretical investigations of diarylimidazole derivative with application as a fluorescence sensor for Fe(III)

Abstract

A diarylimidazole derivative, 2-(2,4-difluorophenyl)-3-(3,5-dimethoxy phenyl)-4,5-diphenyl-1H-imidazole (DFMPI), comprising of electron withdrawing and electron donating substituents, has been designed and synthesized via a four component assembling of benzil, 2,4-difluorobenzaldehyde, 3,5-dimethoxybenzenamine and ammonium acetate in a medium of ethanol. The compound has been characterized by using FT-IR, 1H NMR, 13C-NMR spectral and single crystal XRD analyses. Single crystal X-ray analysis reveals that the compound crystallizes in a monoclinic P21/n space group. Absorption and emission spectral studies display its characteristic application as selective sensing of ferric ion. Theoretical calculations have been performed to calculate the electric dipole moment (μ) and hyperpolarizability (β) for the molecule and were correlated for NLO applications. The non-zero tensor components of the diarylimidazole derivative show that they possess prospective non-linear optical (NLO) behaviour. From the optimized geometry of DFMPI, HOMO-LUMO energies and potential (MEP) energy surfaces have been calculated, which shows the existence of intramolecular charge transfer. In addition, the reactivity of the synthesized molecule using various descriptors like Fukui functions, local softness, electrophilicity, electronegativity and hardness have been studied and discussed.