Front Cover: σ‐Electrons Responsible for Cooperativity and Ring Equalization in Hydrogen‐Bonded Supramolecular Polymers

The cover picture shows σ-electrons, which by traveling through the chain, strengthen the hydrogen bonds in squaramide linear chains. This increasing gain in stability becomes more pronounced when the chain elongates and originates from the donor–acceptor charge transfer interaction within the σ-electronic system. As the charge flows from one end of the chain towards the other, it amplifies the charge separation across the chain, resulting in a stronger hydrogen bond with the new incoming monomer. More information can be found in the Full Paper by Célia Fonseca Guerra, and co-workers.