Synthetic protocols for the preparation of nanomaterials chemically are expensive, too much time taking and unfriendly to the environment, therefore, phyto-assisted approach has the potential to be a promising alternative strategy for the synthesis of nanomaterials. Herein, Fe2O3 with nanoflower-like architecture (Fe2O3 NFs) was prepared using Moringa oleifera leaf extract, and characterized by employing several analytical techniques. The antimicrobial activity of the prepared Fe2O3 NFs was evaluated against the bacteria viz. Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, Escherichia coli by using the serial dilution method. The results suggested that Fe2O3 NFs possess comparable antimicrobial activity comparable with streptomycin against the used pathogens.

Due to their distinct structural, electrical, and electrochemical properties, macrocyclic complexes have been recognized as potential models in a variety of areas, including electrocatalysis, biology, and medicine. In this study, two hexa-aza-macrocyclic complexes of Ni(II) and Cu(II) transition metals (denoted as [NiL] and [CuL]) were synthesized via template procedure. Based on the results of multiple spectroscopic characterization, a distorted octahedral geometry was proposed for both the complexes. The electrochemical results showed that the macrocyclic framework can stabilize the unusual oxidation states of Ni(II) and Cu(II) transition metal ions, as evidenced by the corresponding quasi-reversible Ni(II)/(III) and Cu(II)/(III) redox couples. Additionally, both the complexes were found to be promising antibacterial agents against the B. subtilis, S. aureus, P. aeruginosa, and E. coli pathogens. The Cu(II) complex had the largest inhibition zone (22[Formula: see text]mm) against B. subtilis, while the Ni(II) complex had the smallest (15[Formula: see text]mm).

The monitoring of shifting of the redox potential of macrocyclic complexes towards anodic or cathodic regions, which acts as a mediator in many electrocatalytic events, is made possible by inserting electron donating or withholding groups into their frameworks. Herein, using a template strategy, two [14]membered N 4 -macrocyclic complexes (denoted as complex A and complex B) with similar molecular cores but different phenyl moieties were prepared and characterized using multiple characterization techniques. The characterization results suggested a saddle-shaped geometry for these complexes, which might be due to the steric repulsions between the benzenoid and amidic moieties on the macrocyclic framework, as also supported by theoretical computations. Further, to investigate the electrochemical behaviors of these complexes, cyclic voltammetry was used and found that the Fe 3+/2+ redox potential was systematically shifted in anodic direction with the increment of phenyl moieties on the [14]-membered N 4 -macrocyclic core. DFT calculations indicated the down-shifting in the most occupied molecular orbital due to the increased phenyl conjugation, which could be correlated with the shifting of Fe 3+/2+ redox potential. Biological evaluation of these complexes has also been carried out.