Coordination-Driven Folding in Multi-ZnII-Porphyrin Arrays Constructed on a Pillar[5]arene Scaffold

5 years ago

Coordination-Driven Folding in Multi-ZnII-Porphyrin Arrays Constructed on a Pillar[5]arene Scaffold

Haifa Ben Aziza, Thi Minh Nguyet Trinh, Christian Bijani, Jean-François Nierengarten, Yannick Coppel, Matthieu Chessé, Michel Holler, Béatrice Delavaux-Nicot, Emmanuel Maisonhaute, Eric Meichsner, Iwona Nierengarten, Rym Abidi

Pillar[5]arene derivatives bearing peripheral porphyrin subunits have been efficiently prepared from a deca-azide pillar[5]arene building block (17) and ZnII-porphyrin derivatives bearing a terminal alkyne function (9 and 16). For the resulting deca-ZnII-porphyrin arrays (18 and 20), variable temperature NMR studies revealed an intramolecular complexation of the peripheral ZnII-porphyrin moieties by 1,2,3-triazole subunits. As a result, the molecules adopt a folded conformation. This was further confirmed by UV/Vis spectroscopy and cyclic voltammetry. In addition, we have also demonstrated that the coordination-driven unfolding of 18 and 20 can be controlled by an external chemical stimulus. Specifically, addition of an imidazole derivative (22) to solution of 18 or 20 breaks the intramolecular coordination at the origin of the folding. The resulting molecular motions triggered by the addition of the imidazole ligand mimic the blooming of a flower. Molecular flowers: Deca-ZnII-porphyrin arrays constructed on a pillar[5]arene scaffold adopt a folded conformation due to intramolecular complexation of the ZnII-porphyrin moieties by 1,2,3-triazole subunits. An external chemical stimulus can trigger the unfolding of these compounds thus mimicking the blooming of a flower.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701622