Cooperativity in Hydrogen‐Bonded Macrocycles Derived from Nucleobases

Abstract

Introducing a rigid linear π‐conjugated acetylene linker into a supramolecular building block consisting of a hydrogen‐bond donor side and a hydrogen‐bond acceptor side yields a decrease of cooperativity in the resulting formed quartet. This follows from our Kohn‐Sham molecular orbital and Voronoi deformation density analyses of hydrogen‐bonded macrocycles based on guanine and cytosine nucleobases. The acetylene linker abstracts electron density from the hydrogen‐bond acceptor and donor, making the hydrogen‐bond acceptor become more negatively charged whereas the hydrogen‐bond donor becomes more positively charged and hence suppressing the donor–acceptor charge transfer interaction between the interacting fragments. This, ultimately, hampers the cooperativity in the hydrogen‐bonded macrocycle. We envision that these findings could open the door to new design principles for the development of novel hydrogen‐bond supramolecular macrocycles.