Vol. 117 No. 1 (2021)

Unlike Physics or Biology, a philosophical approach to the most fundamental aspects of Chemistry is practically absent from the debate in the community, except in the small circle of specialists in the philosophy of Chemistry. However, as I argue in this short paper, debates such as the connection between reductionism and extensivity of a discipline and its scientific relevance, or the relationship of dependency and subsidiarity of Chemistry with Physics and Biology, deserve greater attention from our community and should be introduced to students of Chemistry.

Keywords: Filosofía de la Química, pedagogía Química, reduccionismo, extensividad, propiedades emergentes.

a review is made of the two main synthetic approaches to vitamin B12, one of which was successfully accomplished. The mechanisms of some key steps in the synthetic sequences are also discussed. In addition, the mechanisms of two biological reactions involving corrinoid factors related to vitamin B12 of foremost importance for human beings are presented.

With the increasing trend in the use of electronic devices equipped with screens, the sustainability and power consumption become more important. Thus, OLED (Organic Light-Emitting Diodes) devices based on Thermally Activated Delayed Fluorescence (TADF) allow the production of advanced light emission devices with low energy consumption and (heavy) metal-free. Among the possible emitting molecules, heterodoped nanotriangulenes offer a promising alternative, provided the energy difference between their singlet and triplet excited states is low enough. This property can be accurately studied with sophisticated quantumchemical methods such as CASSCF, NEVPT2 or SCS-CC2, instead of TD-DFT, for the systems tackled here.

Keywords: OLEDs, TADF, organic radicals, TD-DFT, CASSCF, NEVPT2.

There is an increasing interest in conjugated push-pull chromophores that incorporate nitrogen heterocycles as electronwithdrawing units because their photophysical properties are highly sensitive to external stimuli. In this respect, reversible protonation causes dramatic color changes, whereas the emission is often quenched. Nevertheless, in some cases the presence of acid prompts the appearance of emission bands of complementary colors. Thus, white and multicolor photoluminescence both in solution and in the solid state can be obtained by the controlled protonation of the azaheterocyclic ring. With a suitable design, these compounds have potential applications in the development of colorimetric pH sensors and the fabrication of OLEDs based on one single material.

Keywords: white-light emission, push-pull chromophores, nitrogen heterocycles, protonation, photoluminescence.

The first floor of the building of the Institute of Chemistry of the Escuela Nacional de Ciencias Químicas was inaugurated on April 4, 1941. It was sponsored by El Colegio de México as a result of the initiative of Alfonso Reyes and Daniel Cosío. Dr. Antonio Madinaveitia, its Spanish director, had established natural products as a line research. On July 25, 1939, the first budget for research was spent on well-established work plans and on the line of research that continues to be studied until now. It is relevant to appreciate the role played by Antonio Madinaveitia, Alfonso Reyes and Daniel Cosío in their founding.

This article is divided into four parts. The first part describes how homeopathic products are prepared and shows that, according to Avogadro’s Principle, the vast majority of them do not contain the product that is intended to be administered to the patient, or, in other words, they contain only the excipient. A few only contain such small quantities that, as pharmacology establishes, it can be assumed that they lack the capacity to cure any disease. According to the above, all scientific studies prove that their healing capacity is not superior to that of a placebo. The second part is dedicated to those who wish to know the history of homeopathy, the third reviews the opinions of some scientific institutions about it and the fourth includes some general considerations.

The Spanish Illustration (1700-1808 or 1814) ended without the opening of the Royal Academy of Natural Sciences and without the continuation of the related Royal Laboratory of Chemistry in Madrid, inaugurated in 1788 by the chemist, pharmacist and professor Pedro Gutiérrez Bueno. In Mexico, the Royal Botanical Garden and the Royal Mining Seminar continued, inaugurated in 1788 and 1792, respectively. Chemistry flourished in both establishments, highlighting the contribution of the pharmacist and botanist Vicente Cervantes Mendo, professor of Botany, the first translator into Spanish of the Traité élémentaire de Chimie (1789), published in 1797 for the use of the mining establishment.

Keywords: Royal Academy of Natural Sciences of Madrid, Royal Laboratory of Chemistry of Madrid, Pedro Gutiérrez Bueno, Royal Botanical Garden of Mexico, Vicente Cervantes Mendo, Royal Mining Seminar of Mexico