A unique class of tubular polymer structures that are soluble in apolar organic solvents but are endowed with polar pores has been created through the rational design of the monomer units, which self...

Madrid Symposium on Polymers . . November 12th-14th, 2025

Inspired by the extraordinary attributes displayed by nanotubes in Nature, the creation of self-assembled nano-sized hollow tubes is an area of significant and growing interest given its potential app...

Lawrence Berkeley National Lab’s (LBNL) Materials Science Division (MSD) has an opening for an Organic and Polymer Postdoctoral Fellow where Dr....

If we aim to develop efficient synthetic models of protein receptors and enzymes, we must understand the relationships of intra- and intermolecular interactions between hosts and guests and how they mutually influence their conformational energy landscape so as to adapt to each other to maximize binding energies and enhance substrate selectivities. Here, we introduce a novel design of cofacial (ZnII)bisporphyrin cages based on dynamic imine bonding, which is synthetically simple, but at the same time highly robust and versatile, affording receptors composed of only sp2-hybridized C and N atoms. The high structural rigidity of these cages renders them ideal hosts for ditopic molecules that can fit into the cavity and bind to both metal centers, leading to association constants as high as 109 M–1 in chloroform. These strong binding affinities are a consequence of the remarkable chelate cooperativities attained, with effective molarity (EM) values reaching record values over 103 M. However, we discovered that the cages can still adapt their structure to a more compact version, able to host slightly smaller guests. Such a conformational transition has an energy cost, which can be very different depending on the direction of the imine linkages in the cage skeleton and which results in EM values 2–3 orders of magnitude lower. This interplay between cooperativity and conformational adaptability leads to strong and unusual selectivities. Not only these metalloporphyrin receptors can choose to bind preferably to a particular guest, as a function of its size, but also the guest can select which host to bind, as a function now of the host’s conformational rigidity. Such highly cooperative and selective associations are lost, however, in related flexible receptors where the imine bonds are reduced.