This article creates a green strategy to fabricate a highly crystalline olefin-linked pyrazine-based covalent organic framework (COF) with high robustness and porosity under solvent-free conditions. This study opens up new possibilities for the green synthesis of advanced materials and provides important guidance for the rational design and synthesis of polymeric materials for proton-exchange membrane fuel cell applications.

This article is the fourth paper of the Special Issue Memory and Criticality. It bridges the the theoretical debate on the role of memory and criticality discussed in the three earlier manuscripts, with a review of key concepts in biology and focus on cell-to-cell communication in organismal development. The authors suggest that in conjunction with morphogenetic gradients, there exist gradients of information transfer creating cybernetic loops of stability and disorder, setting the stage for adaptive capability. Criticality, therefore, appears to be an important factor in the transmission, transfer and coding of information for complex adaptive system development.