Vol. 120 No. 1 (2024)

The direct functionalization of hydrocarbons catalyzed by palladium complexes allows the formation of new C–C bonds from the available raw materials, avoiding the need to prepare the reactants needed in conventional C–C cross coupling reactions. Thus, this is a more sustainable alternative. These reactions require the activation of C–H bonds which is a difficult process, and it is affected by serious selectivity issues. This article is intended to give an overview of the types of C–H functionalization reactions catalyzed by palladium complexes, as well as the main approaches in the area to achieve more active catalytic systems and more selective reactions.

Keywords: homogeneus catalysis, C–H activation, C–H functionalization, palladium, metal-ligand cooperation

Oxidative addition is a cornerstone process in organometallic chemistry that plays a pivotal role as a key stepin numerous transition-metal-catalyzed coupling reactions. Recent years have witnessed the emergence of bismuth as amain-group element capable of mimicking and complementing the ability of transition metals to engage in redox catalytic cycles. These processes are also driven by oxidative-addition reactions, which can occur at both Bi(I) and Bi(III) centers. This review article aims to summarize some of the most relevant studies on oxidative addition into well-defined bismuth complexes, paving the way for the development of the rapidly evolving field of bismuth redox catalysis.

Keywords: bismuth, oxidative addition, redox catalysis

Polymer gels, made up of polymer and solvent, have both the cohesive properties of solids and the transport properties of liquids. This duality allows modulating the activity of the gels in a controlled way and elucidating their structural aspects. Gels cover a wide spectrum of different polymers (synthetic and natural), solvents (water is the most common: hydrogels), sizes (macro-, micro- and nanogels) and specific properties, very attractive for their applications. The study of the viscoelastic properties and the application of different models, allows knowing its structural organization. Gels have demonstrated their importance as efficient storage/incorporation systems for solvents and other components, drug release and magnetic hyperthermia, among others. This work briefly summarizes some concepts and focuses on the rheological properties, where the most relevant models and theories applied to both gels and polymeric microgels have been collected.

 

Keywords: gels, microgels, nanogels, hybrid gels, response to stimuli, viscoelastic properties

"Explain and reason the fundamental concepts that are at the base of chemistry by applying the concepts, laws and theories of other scientific disciplines, especially physics ”, is the competence number 6.1 of the Chemistry subject, included in Royal Decree 243/2022. The direction of the dipole moment differs depending on whether one consults Chemistry or Physics texts. This article briefly reflects on this.

Keywords: Direction of the dipole moment, dipole moment, polarity, dipole, Debye