Chemistry plays a fundamental role within the natural sciences, because of its knowledge in itself, its great economic importance and its omnipresence in practically all aspects of our daily lives. But because it is everywhere, it is often forgotten or not mentioned at all.
Chemistry has made an essential contribution to mankind in food and medicines, in clothing and housing, in energy and raw materials, in transportation and communications, in models and substrates for biology and pharmacology, and of course it supplies materials for physics, science and technology, just to mention a few areas of its universality, for these would be countless.
Long before humans began to study chemistry, or even form the concept of science, they used basic chemistry techniques to improve their daily lives. Thus, from the first time early humans lit a fire to generate heat, cooked food (which causes chemical changes in food), or fermented fruit to convert sugars into alcohol, humanity has manipulated the matter around it, as Annenberg Learner explains in her article "Chemistry: Challenges and Solutions" (2023).
Over many millennia, human civilization has progressed from the Stone Age through the Bronze and Iron Ages, where it learned to manipulate materials in more sophisticated ways; For example, the process of smelting these metals to make tools and weapons, to later produce materials that improved their way of life, from soap to medicines, which led to humans first understanding the material in its raw state (what we now call raw materials), from which they could make other new materials by improving their skills to refine or purify them (most of them chemical transformation processes).
However, to understand how chemistry developed into a modern science, one must consider the difference between skilled craftsmanship and scientific research. For example, medieval blacksmiths, potters, cooks and even alchemists are craftsmen; they use and combine materials to create practical products, according to formulations that have been refined and passed down through the ages, often orally, by their predecessors and kept as a great secret, as Annenberg Learner explains.
Of course the artisans (some of them alchemists) were able to experiment and develop new and better products, but they usually do not strive to explain why or how something works in a certain way or how to generate new knowledge that is relevant beyond their own work in their area of expertise.
In contrast, scientific research is a broader but mostly well-established process where scientists observe phenomena and formulate hypotheses in the search for an explanation of the observations or results obtained. The goal is to produce accurate data and results that other researchers can reproduce consistently.
Thus, after going through a period of trial and error in alchemy, chemistry became a formal scientific discipline, when people doing science and research began to analyze and understand chemical processes, rather than just carry them out; this allowed the generation of knowledge with access to a larger number of people through the use of the scientific method.
But let us return to what chemistry involves and ask the classic question: What does chemistry study? The simple answer is that it is the study of matter and the changes it undergoes. One could also say that, as a science, it is based on reproducible facts, phenomena that are verified in the same way when the same conditions prevail. But, we would like you to think beyond the definition, let's say that chemistry is... an incredibly fascinating field of study!!! it is not only about discovering but also about creating.
Thus, chemistry studies the transformation of chemical elements to compounds and from one chemical compound to another, and explains the type of bond that holds atoms together in a chemical species, which is related to its composition and structure. As we know there are many branches of chemistry, but we want to focus your attention to the so-called Supramolecular Chemistry.
Molecular chemistry is mainly concerned with studying and explaining the creation of covalent bonds in molecules, generally of the organic type (compounds that typically contain atoms of C, H, N, O, F, among others, in their structures). However, in this type of compounds there are not only covalent bonds but also the so-called "intermolecular interactions" (interactions between molecules) basically associated with weak non-covalent bonds (electrostatic interactions that can be of the dipole-dipole or ion-dipole type), which are the heart of supramolecular chemistry, according to Stefan Kubik, PhD in Chemistry and author of the book "Supramolecular Chemistry: from concepts to applications" (2021).
Intermolecular interactions are important in areas of chemistry such as medicinal and materials chemistry; however, nature provides numerous examples of supramolecular chemical species.
One of the most relevant and that constitutes a true paradigm of a supramolecular system is the formation of the DNA double helix that is formed by hydrogen bridges and results in a functional and flexible structure with the ability to pre-organize in response to certain stimuli under specific conditions, Figure 1.
Another example, which is never thought of but is probably the fundamental part of life existing on our planet, are the intermolecular interactions in water, commonly known as hydrogen bridges as explained on its website by the non-profit foundation Khan Academy, founded by Salman Khan in 2008. These make such a small molecule, which by its size and state of aggregation should be its vapor phase, have critical temperatures around room temperature (melting temperature 0°C, boiling temperature 100°C), which allows it to be in its liquid state of aggregation due to the hydrogen bridges formed in the compound, which favored the growth and development of life on our planet, Figure 1.
Figure 1. intermolecular interactions in DNA, water and other molecules. Creative Commons license
So, Supramolecular Chemistry, whose name was coined by one of its pioneers Jean-Marie Lehn, who chose from Latin the prefix ʹsupraʹ to indicate that supramolecular chemistry transcends or is larger in size than molecular chemistry. Professor Lehn wrote in 1995, "Beyond molecular chemistry based on covalent bonding lies the field of supramolecular chemistry whose goal is to gain control over intermolecular bonds. It is concerned with the next step in increasing complexity beyond molecules toward supermolecules and organized molecular systems."
Professor Lehn, together with Donald Cram and Charles Pedersen, received the Nobel Prize in Chemistry in 1987 for the innovations that were established in this scientific field: chemistry beyond the molecule. This phrase implies that supramolecular systems consist of structurally defined sets of molecules interacting with themselves and especially with each other, whose formation is controlled by organizational principles encoded within structures with individual components.
To recapitulate or put it another way, two or more molecules (generally of different compounds) associate to give rise to larger and more complex systems: the supramolecules! These are weakly bound together by associations known as intermolecular interactions which generate an association of molecules. So as mentioned by Mondragon and Dominguez in the journal Science in 2018, Supramolecular Chemistry studies the interactions between molecules, molecular recognition and the formation of supramolecular aggregates, which can be seen in Figure 2.
Figure 2. Examples of supramolecular structures. Creative Commons license
Supramolecular chemistry has been going from strength to strength in recent decades, with a huge impact ranging from catalysis to materials science and biochemistry. In 2022, at the meeting of the Macrocyclic and Supramolecular Chemistry Group, held at the University of Nottingham, UK, several experts in the field gave their opinion and answer to the question: what are the challenges for Supramolecular Chemistry in the years to come?
Beatrice Collins, researcher at the University of Bristol, UK, said: "One of the big challenges is the development of new synthetic methods that will drive the next generation of molecular machines".
Anna Slater, a researcher at the University of Liverpool, also UK, mentioned, "Ensuring reproducibility and scalability of supramolecular syntheses is a major challenge as non-covalent and/or reversible processes can be difficult to control, mainly due to their sensitivity to environmental conditions."
Letizia Liirò Peluso, researcher at the University of Nottingham, UK, commented, "Related to supramolecular composition and energy conversion devices, supramolecular chemistry offers a route to a more sustainable energy future, in the form of tuning the performance and efficiency of optoelectronic devices for energy conversion, although significant challenges remain in optoelectronics and nanomaterials."
Chemistry has often been considered the central science because it unites other important areas such as physics, mathematics, biology and medicine, among many others, so that knowledge about the nature of chemical species and processes provides invaluable information about a variety of physical and biological phenomena.
Chemistry does not boast about itself, but without it there would never have been achievements such as the treatment of diseases, space exploration and the wonders of technology. This science has revolutionized mankind and is essential to meet our basic needs for food, clothing, housing, health, energy and clean air, water and soil, medicines, as well as energy distribution and the manufacture of technological equipment. Chemistry is everywhere in our daily lives, and if we want to make the best use of it, we need to understand it better and allow scientists to continue working to do this.
As Professor Lehn put it in UNESCO's Courier magazine in 2011, "From split matter to condensed matter, then to organized, living, thinking matter, the developing Universe pushes the evolution of matter toward increasing complexity through self-organization, under the pressure of information. The task of chemistry is to reveal the pathways of self-organization and to trace the paths leading from inert matter, through purely chemical prebiotic evolution, to the creation of life, and beyond, to living and then thinking matter. In this way, it offers the means to interrogate the past, explore the present, and build bridges to the future."
Chemistry applied to new technologies enriches our quality of life by providing new solutions to problems of health, materials and their application to fields such as renewable energies.
Gloria Sánchez Cabrera has a degree in Industrial Chemistry from the Benemérita Universidad Autónoma de Puebla and a PhD in Science with a specialty in Inorganic Chemistry from the Chemistry Department of CINVESTAV-IPN. She completed a Postdoctorate at the Department of Electrical Engineering (Molecular Electronic Devices). University of South Carolina, Columbia, SC, U.S.A. Full-Time Research Professor C in the Academic Area of Chemistry at UAEH since 2003. With research stays at the Institute of Organometallic Chemistry "Enrique Moles" of the University of Oviedo, Spain 1998 and at the Department of Inorganic Chemistry. Indiana University. U.S.A., 2007 and 2008. She is a National Researcher (SNI) Level I and professor with PRODEP desirable profile recognition, has 30 indexed articles and has directed or co-directed 20 Bachelor's theses, 10 Master's theses, 7 PhD theses, some of them in process. She belongs to the Academic Body of Experimental and Computational Inorganic Chemistry (CAQIEC) and is currently working on the research project: Development of new organometallic transition metal complexes derived from N-heterocyclic ligands with potential biological activity.
https://www.uaeh.edu.mx/campus/icbi/investigacion/quimica/curriculums/gsc.html
gloriasa@uaeh.edu.mx
Francisco Javier Zuno Cruz has a degree in Chemical Engineering from UAM-Azcapotzalco and a PhD in Science, specializing in Inorganic Chemistry, from the Department of Chemistry at CINVESTAV-IPN. He has a Postdoctorate in the Department of Electrical Engineering (Molecular Electronic Devices) at the University of South Carolina, Columbia, SC, U.S.A. Full Time Research Professor C in the Academic Area of Chemistry at UAEH since 2003. With research stays in the Department of Inorganic Chemistry. Indiana University. U.S.A. 2007 and 2008. He is a National Researcher (SNI) Level I and professor with PRODEP desirable profile recognition, has 29 indexed articles and has directed or co-directed 20 Bachelor's theses, 10 Master's, 7 PhD, some in process. He belongs to the Academic Body of Experimental and Computational Inorganic Chemistry (CAQIEC) and develops the research project: Study of macromolecular metallic compounds of groups 8, 10, 11 and its potential catalytic application.
https://www.uaeh.edu.mx/campus/icbi/investigacion/quimica/curriculums/fjzc.html
fjzuno@uaeh.edu.mx