A step back. The last time an Italian scientist was close to winning the Nobel Prize for Chemistry was in 2016, when the prize was awarded to Jean-Pierre Sauvage, Fraser Stoddart and Ben Feringa for their “molecular machines”. The Italian in question was Vincenzo Balzani, now professor emeritus at the Department of Chemistry “G. Ciamician” of the University of Bologna. Balzani had been co-author of numerous fundamental articles by Sauvage and Stoddart, in which he had supervised the characterization and interpretation of the properties of the complex molecules synthesized by the two colleagues. The Nobel Committee had preferred Feringa to him, a Dutch scientist, an extraordinary synthesizer of elegant and imaginative systems, which however added little to the innovations brought by Stoddart and Sauvage with the chemist from Bologna. It was a choice that had caused much discussion, that had seemed unfair to most, and that had gone down badly in particular with the Italian chemical community.
Molecular machines, awarded with that 2016 Nobel, are a niche of supramolecular chemistry, the most beautiful, exotic and creative type of chemistry that one can imagine. Have we, Italian chemists, finally metabolized that 2016 insult? The XVI National Congress of Supramolecular Chemistry, held at the University of Pavia from 10 to 13 September, made the point, and the answer is a resounding yes. After all, there is little to digest or metabolize. Chemistry, like all hard sciences, is a flow that advances regardless of the episodes, an unstoppable machine made by the group of scientists, where everyone builds the building of knowledge one brick at a time, and the disappointments of one do not affect the work of the other. And if we look at Italian research, supramolecular chemistry has a powerful and healthy engine. When we talk about “supramolecular”, we mean the chemistry of molecules that interact with each other to create “supermolecules”, large aggregates capable of carrying out new and different functions. The micelles contained in soaps, cell membranes, the myosin responsible for muscle contractions are some of the hundreds of examples of supermolecules that nature abounds in, and from which supramolecular chemistry draws inspiration to create new ones, as extraordinarily complex in synthesis as they are elegant in their conception and in the scientific concepts that underlie them. Supermolecules capable of functioning as elevators, shuttles, rotors, or capable of spontaneously knotting and intertwining like the five Olympic rings or the double helix of DNA, are some of the spectacular results obtained by supramolecular chemistry since the years of its birth, the seventies of the last century. But what purpose did these strange supermolecules serve? For nothing, or at least that’s what the organic, inorganic, industrialists, that is, the scientists of the most traditional and productive areas of chemistry, ironically labeled them. What was seen at the XVI National Congress in Pavia confirms the paradigm shift of the last decade: elegance and creativity are still partly there, but the systems presented by Italian supramolecularists are now decidedly aiming towards applications. For example, in catalysis, that is, in making otherwise slow reactions faster, without spending energy on what is the natural accelerator of any reaction, the increase in temperature. As in the case presented by the Department of Chemistry and Biology of the University of Salerno, which showed how this can be done by taking resorcinarenes, relatively small concave organic molecules, and making them assemble thanks to bridges of water molecules. A spherical supermolecule is formed, inside which the reagents are easily transformed into products, solicited by interactions with the walls of the container. Other highly represented applications were those in the medical field, such as the research presented by the Department of Pharmaceutical and Health Sciences of the University of Catania: self-assemblies of amphiphilic polymers that function as vectors for a collection of molecular species. Irradiated by light, they release drugs, transform oxygen into reactive species, and generate heat, ensuring a simultaneous attack on multiple fronts capable of destroying tumor cells. Numerous contributions have also been designed to remedy the damage caused by man, such as the reduction of carbon dioxide from the air or the removal of pollutants from water. Research by the Department of Chemistry at the University of Pavia has shown how synthetic cage molecules form membranes capable of selectively capturing CO2 from the air, while allowing oxygen to pass through, and work by the Department of Chemistry at the University of Parma has shown how cyclic molecules, called cavitands, with a hydrophobic interior and a hydrophilic exterior, effectively capture highly carcinogenic pollutants such as polycyclic aromatic hydrocarbons from water.
It is debatable whether the slide from pure beauty to practical utility of supramolecular chemistry was spontaneous, and the answer is probably no. For decades, academic research has been solely competitive, that is, it is carried out thanks to external funding that comes through public tenders. The projects submitted to the tenders of the various funding bodies (from the MUR to the European Community, from the regions to the banking foundations) must adapt to their guidelines, and it has become clear that the proposal of a project without immediate applicative implications has no hope, no matter how elegant, imaginative or even ingenious its chemistry may be. Many scientists think it is an own goal, and it is difficult to disagree, because it is on the great “useless” discoveries of the past that the successful technologies of today have been built. But it is the funding bodies that dictate the law. It is comforting then that there are still elegant and potentially useful researches, like the one that closed the Pavia congress, presented by the Department of Chemical and Pharmaceutical Sciences of the University of Trieste: synthetic cyanobacteria. These are spherical supermolecules made of many different smaller molecules, which in reality are not “alive” (they cannot reproduce).
However, they can do two spectacular things, both thanks to simple light radiation: move autonomously, like real bacteria, and above all “break” water into oxygen and hydrogen. And the latter is one of the main candidates for the production of clean energy of the future.