Synthesis, spectral, DFT calculations and antibacterial studies of Fe(III) complexes of new fluorescent Schiff bases derived from imidazo[4',5':3,4]benzo[1,2‐c]isoxazole

Abstract

New fluorescent heterocyclic ligands were synthesized by the reaction of 8‐(4‐chlorophenyl)‐3‐alkyl‐3H‐imidazo[4',5':3,4]benzo [1,2‐c]isoxazol‐5‐amine with p‐hydroxybenzaldehyde and p‐chlorobenzaldehyde in good yields. The coordination ability of the ligands with Fe3+ ion was examined in an aqueous metanolic solution. Schiff base ligands and their metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and NMR spectra. The optical properties of the compounds were investigated and the results showed that the fluorescence of all compounds is intense and their obtained emission quantum yields are around 0.15 – 0.53. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using density functional theory (DFT) methods. The DFT‐calculated vibrational wavenumbers and NMR chemical shifts are in good agreement with the experimental values, confirming suitability of the optimized geometries for Fe(III) complexes. Also, the 3D‐distribution map for HOMO and LUMO of the compounds were obtained. The new compounds showed potent antibacterial activity and their antibacterial activity (MIC) against Gram‐positive and Gram‐negative bacterial species were also determined. Results of antibacterial test revealed that coordination of ligands to Fe(III) leads to improvement in the antibacterial activity.

Synthesis, electrochemical, photophysical, and photovoltaic properties of new fluorescent compounds: 3 H ‐benzofuro[2,3‐ b ]pyrazolo[4,3‐ f ]quinoline

“…As shown in Figure 1, the absorption spectrum of compounds 3a‐e has an absorption maximum in range of 385 to 395 nm at 7 × 10 −6 mol L −1 in acetonitrile as a solvent. The comparison method was used to determine the fluorescence quantum yield (Φ F ) of the compounds 3a‐e in MeOH as a solvent 44‐48 . The Φ F of the compounds 3a‐e amounts to the range of 0.73 to 0.80, which may be compared to the quantum yield of the well‐known fluorescent dye fluorescein, which adds up to 0.79.…”

Design, Synthesis, and Biological Evaluation of Phenyloxadiazole Sulfoxide Derivatives as Potent Pseudomonas aeruginosa Biofilm Inhibitors

“…Benzo heterocyclic skeleton is one of the most important structural components and biological compounds in pharmaceutical chemistry. Owing to the rich structural diversity of the bioactive benzo-heterocyclic ring, it has become an important structural component in many pharmaceutical preparations [33][34][35]. Both allicin and ajoene have sulfoxide structures, and we hypothesized that benzoheterocyclic sulfoxide might also have quorum sensing activity.…”

New mixed‐ligand iron(III) complexes containing thiocarbohydrazones: Preparation, characterization, and chemical reactivity analysis through theoretical calculations

“…[16][17][18] Fe(III) complexes have good antibacterial activity against a wide range of bacteria. [19][20][21][22] At the same time, iron(III) metal ions play a vital role in biological processes. The design, synthesis, and characterization of iron complexes are important in many fields as they provide synthetic models for iron-containing enzymes.…”