Chemistry is a science whose goal is not only to discover, but also and above all to create, since it is the art of making matter more complex. To grasp the logic of the recent evolution of chemistry, we have to go back in time and go back some four billion years.
by Jean-Marie Lehn
Chemistry plays a fundamental role, both through its place in the natural sciences and knowledge, and through its economic importance and its omnipresence in our daily lives. By dint of being present everywhere, its existence is often forgotten, and it even risks going completely unnoticed. It’s a science that doesn’t tend to put on a show, but without it many of the therapeutic feats, spatial feats and technical marvels that we all consider spectacular would not have happened. Chemistry makes a decisive contribution to meeting humanity’s needs for food, medicine, clothing, housing, energy, raw materials, transport and communications. It also supplies materials to physics and industry, supplies models and substrates to biology and pharmacology, and supplies properties and procedures to science and technology in general.
A world without chemistry would be devoid of synthetic materials, and therefore devoid of telephones, computers, synthetic fabrics and movie theatres. It would also be a world devoid of, among other things, aspirin, soaps, shampoos, toothpaste, cosmetics, birth control pills, glue, paint and paper, so there would be no newspapers or books .
Let’s not forget that chemistry helps art historians uncover some of the secrets of how the paintings and sculptures we admire in museums are made. Let’s also remember that it allows the forensic science to analyze the samples taken from the “crime scene” and thus identify the culprits more quickly, and finally let’s also know that it is they who discover the molecular subtleties of the dishes that captivate our palate.
Along with physics, which deciphers the laws of the universe, and biology, which deciphers the rules of life, chemistry is the science of matter and its transformations. Its highest expression is life itself. It plays a key role in our understanding of material phenomena, as well as in our ability to act on them, modify them and control them.
For about two centuries, molecular chemistry has created a vast array of increasingly complex molecules and materials. From the real revolution in the synthesis of urea, carried out in 1828, which demonstrated the possibility of obtaining an organic molecule from a mineral compound, to the realization of the synthesis of vitamin B12 in the 1970s, this discipline has continued to consolidate its power. on the structure and transformation of matter.
The molecule as a Trojan horse
Beyond molecular chemistry extends the immense field of so-called supramolecular chemistry, which does not study what happens inside molecules, but rather how they behave with each other. Its objective is to understand and control their mode of interaction and the way in which they transform and join, ignoring the other molecules. The German scientist Emil Fischer, Nobel Prize in Chemistry (1902), used the comparison of the key and the lock to state this phenomenon. Today, it is called “molecular recognition”.
It is in the field of biology that the role of molecular interactions is most surprising: the protein units that come together to form hemoglobin; white blood cells which recognize and destroy foreign bodies; the AIDS virus finding its target and entering it; the genetic code that is transmitted by writing and reading the alphabet of protein bases, etc. A very eloquent example is that of the “self-organization” of the tobacco mosaic virus, formed by a group of no less than 2,130 simple proteins structured in a helical tower.
The efficiency and elegance of natural phenomena so fascinate a chemist that his temptation is to try to reproduce them, or to invent new processes to create new molecular architectures with multiple applications. Why not imagine, for example, the development of molecules capable of transporting a DNA fragment intended for gene therapy to the center of a chosen target? These molecules would be like “Trojan horses” that would allow their passenger to cross barriers such as cell membranes, considered impassable.
Armed with patience, many researchers around the world are building – I would say “tailor-made” – supramolecular structures. They observe how the molecules, mixed in an apparent disorder, come together on their own, recognize each other and then gradually unite until they form spontaneously, but perfectly controlled, the final supramolecular structure.
For this reason, inspired by the phenomena that occur in nature, the idea of causing the appearance of supramolecular assemblies and controlling them, that is to say, carrying out “molecular programming”, arose. The chemist will design the basic “bricks” (molecules with certain structural and interaction properties) and then apply the “cement” (the assembly code) that will put them together. Thus you will obtain a superstructure by self-organization. The synthesis of molecular building blocks capable of self-organization is much simpler than the synthesis of the final building would be. This line of research opens up vast prospects, particularly in the field of nanotechnology: instead of manufacturing nanostructures, we let them manufacture themselves by self-organization and thus move from manufacturing to self-manufacturing.
Even more recently, a so-called adaptive chemistry has appeared, in which the system itself makes a selection among the available bricks and is able to adapt the constitution of its objects in response to the requirements of the environment. This chemistry, which I call “dynamic constitutional chemistry”, has a Darwinian distribution.
From matter to life
In the beginning was the original explosion, the “Big Bang”, and physics ruled. Then, with milder temperatures, came chemistry. The particles formed atoms and these came together to produce more and more complex molecules which in turn joined together into aggregates and membranes, giving rise to the first cells from which life sprouted on our planet. This happened about 3.8 billion years ago.
Desde la materia viva hasta la materia condensada, primero, y luego desde esta última hasta la materia organized, viva y pensee, la expansión del universo nutre la evolución de la materia hacia un aumento de su complejidad mediante la auto organización y bajo la presión de information. The task of chemistry is to reveal the ways of self-organization and to trace the paths which lead from inert matter – by a purely chemical prebiotic evolution – to the birth of life, and from there to living matter, then to thinking matter. Chemistry therefore gives us the means to question the past, to explore the present and to build bridges towards the future.
Through its object – molecules and materials – chemistry expresses its creative force, its power to produce new molecules and materials – authentically new because they do not exist before being created – by rearrangements of atoms in combinations and new and infinitely varied structures. . Due to the plasticity of forms and functions of the object of chemistry, it bears a certain resemblance to art. Like the artist, the chemist fashions the products of his imagination into matter. The stone, the sounds and the words do not contain the work that the sculptor, the composer and the writer model with these elements. In the same way, the chemist creates original molecules, new materials and unprecedented properties from the elements that make up matter.
The essence of chemistry is not only to discover, but also to invent and above all to create. The chemistry book is not only to read, but also to write. The score of chemistry is not only to play it, but also to compose it.
