Schiff bases are diverse organic compounds with an azomethine structure (–C=N–), holding potential in both chemistry and biology. They serve as catalysts, stabilizers, and exhibit various biological activities. The molecular structure of Schiff bases influences their biological properties, including antimicrobial effects. Redox-active compounds with more negative potentials tend to be more effective against microbes. In one of our recent studies, we explored the antimicrobial properties of two Schiff bases derivatives, SB-1 ((E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) and SB-2 ((E)-2-((4-nitrobenzilidene)amino)aniline). SB-1 showed antibacterial activity against certain Gram-positive bacteria, while SB-2 did not. The difference in their cyclic voltametric profiles, especially SB-1’s more negative reduction potential, prompted us to carry out further characterizations, including scan-rate studies, solvent analysis, and computational calculations. We found that SB-1, which presents a stable intramolecular hydrogen bond, undergoes irreversible oxidation, likely at the –NH2 group, and a quasi-reversible reduction via an intramolecular reductive coupling of the (–C=N–) azomethine group, supported by orbital theoretical calculations. This research sheds light on the potential applications of Schiff bases in antimicrobial contexts, guided by their redox properties and structure. –C=N–, CN –C=N– , C N biology catalysts stabilizers activities effects Redoxactive Redox active microbes studies derivatives SB1 SB 1 SB- E4amino33,5ditertbutyl2hydroxybenzylideneamino E4amino335ditertbutyl2hydroxybenzylideneamino Eaminoditertbutylhydroxybenzylideneamino E 4 amino 3 3,5 di tert butyl 2 hydroxybenzylidene 5 ((E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino SB2 E24nitrobenzilideneaminoaniline. E24nitrobenzilideneaminoaniline Enitrobenzilideneaminoaniline nitrobenzilidene aniline . ((E)-2-((4-nitrobenzilidene)amino)aniline) Grampositive Gram positive bacteria not profiles SB1s SBs s characterizations scanrate scan rate analysis calculations SB1, 1, bond oxidation NH2 NH –NH group quasireversible quasi reversible (–C=N– contexts –C=N E4amino33 5ditertbutyl2hydroxybenzylideneamino ditertbutyl hydroxybenzylideneamino 35 3, nitrobenzilideneaminoaniline ((E)-2-((4-nitrobenzilidene)amino)aniline (–C=N Eamino E4amino3 ditertbutylhydroxybenzylideneamino E4amino

Abstract: Chilean soils derived from volcanic ashes are a natural source of iron oxides. Due to their properties, mineralogy, and surface characteristics, iron oxides from Chilean soils are potential candidates for technological applications such as heterogeneous catalysis. However, before a direct application in catalysis, pre-treatment methods are necessary to concentrate iron oxides from bulk volcanic soils. Here, we provide a comprehensive review of pre-treatment strategies for iron oxide concentration including physical separation and selective chemical dissolutive methods for application in catalytic processes, such as the water gas shift (WGS) and Fenton reactions. For preparation of WGS catalyst from volcanic soils, thermal treatment has been demonstrated to be effective, yielding enhanced results for Andisols compared to Ultisols. Based on mineralogical characterisation, it seems that WGS reaction efficiency depends on mineralogical phase shift and the changes of Fe2+/Fe3+ ratio, produced through heating. In addition, Ultisols have shown as efficient catalysts in Fenton and Fenton-like processes, after application of physical and chemical pre-treatments to different size-fractions of the soil sample, improving the yield performance of catalysts. Magnetic separates from the Ultisol sand fraction (compared to the silt+clay fractions) demonstrate the best catalytic performance as Fenton reagent due to their natural magnetite and titanomagnetite content. Application of NaOH selective dissolutive treatment to silt+clay fraction of volcanic soils also produces Fenton and Fenton-like catalyst with improved performance. Our review indicates that catalytic performance can be explained not only by the iron oxide mineral content but also by their characteristics and magnetic properties. The application of the appropriate physical and chemical pre-treatment methods can modulate and enhance the catalytic capabilities of iron oxides from volcanic soils.

(E)-2-{[(2-Aminopyridin-3-yl)imino]-methyl}-4,6-di-tert-butyl-phenol ( 3: ), a ligand containing an intramolecular hydrogen bond, was prepared according to a previous literature report, with modifications, and was characterized by UV-vis, FTIR, ¹H-NMR, 13C-NMR, HHCOSY, TOCSY and cyclic voltammetry. Computational analyses at the level of DFT and TD-DFT were performed to study its electronic and molecular structures. The results of these analyses elucidated the behaviors of the UV-vis and electrochemical data. Analysis of the transitions in the computed spectrum showed that the most important band is primarily composed of a HOMO→LUMO transition, designated as an intraligand (IL) charge transfer.

In this research a comparative study of the starting unit chain length effect on the electropolymerization of thiophene or its oligomers was carried out considering mono (1Th), bi (2Th), ter (3Th), tetra (4Th) and sexi (6Th)-thiophene as starting units. The deconvolved transient allows stating that the growth of polythiophene (PTh) employing each of the starting units have the same predominant contribution to the nucleation and growth mechanism (NGM). The others contributions disappear as the length of the starting unit chain increase. The results were validated by scanning electron microscopy (SEM) of PTh deposits obtained onto SnO2 coated glass, following a potential pulse program. Besides of corroborating the electropolymerization model, this study suggested the possibility of designing and performing suitable experiments leading to the attainment of electro-deposited conductive polymers bearing a desired morphology, appropriated for prospective applications.