We already had the periodic table of the elements: it is time to have that of the molecules

In order to build a periodic table for molecules with multiple types of symmetries, researchers from the Tokyo Institute of Technology have presented a new approach proposing periodic rules to predict the existence of certain molecules.

The new approach is based on an acute observation of the behavior of the valence electrons of atoms that form molecular groups.

Four dimensions

The periodic table of elements It was proposed in 1869, and then became one of the cornerstones of the natural sciences. This table was designed to contain all the elements found in nature in a special design that groups them in rows and columns according to one of its most important characteristics, the amount of electrons.

The new table for the molecules would actually be four-dimensional, because the molecules would be organized according to four parameters: groups and periods (based on their "valence" electrons, similar to the normal periodic table), species (depending on the constituent elements) and families (depending on the number of atoms). According Kimihisa Yamamoto, co-author of the study:

Among the infinite combinations of constituent elements, the proposed periodic table will be a significant contribution to the discovery of new functional materials.

The way forward now is to further expand these tables to molecular groups with other shapes and symmetries and predict stable molecules that have not yet been developed.

Molecular knots

Another table that has been presented recently is that of molecular nodes. Consider a short piece of string: Could we guess which knots are more likely to form if they wrinkle and shake? Synthetic chemists have been working for a long time on a molecular version of this problem and, so far, have managed to synthesize half a dozen types of knots using molecular self-assembly techniques.

But what other types of knots could be made in the future? This is the question that SISSA scientists, in association with the University of Padua, have addressed using computer simulations in this new work published in Nature Communications.

According Mattia Marenda, principal investigator of this study, there is a growing scientific interest in complex molecules. In this context, the possibility of designing and synthesizing new types of molecular nodes is particularly attractive:

With these models, our goal was to discover what new types of molecular nodes, if any, would be easier to obtain with current synthetic chemistry techniques, particularly self-assembly. We find that these types of privileged knots exist, but they are very rare. Only a dozen different topologies can be made among millions of types of simple knots.

The reduced list is similar to a periodic table, since it is organized in rows and columns that reflect different aspects of the expected difficulty of practical realization. The results are backed by recent experiments and this suggests that the table could be useful for experimental chemists to choose target topologies for future studies and applications.

Video: The Periodic Table Song 2018 UPDATE! (November 2019).