Azacalixphyrin : the hidden porphyrin cousin brought to light
A porphyrin aza analogue that contains no pyrrol subunits absorbs in the entire visible region and partly in the near infra-red (up to 1000 nm). The central 16-membered ring containing four nitrogen atoms has 18 delocalized π electrons, and is thus aromatic. This new class of molecules revealed a high stability (even in the presence of water under air) owing to its unusual bis- zwitterionic character. As they are NIR-absorbing organic materials with a very low gap (Eg = 1.01 eV), the potential applications of these macrocycles are diverse and extensive in many technological sectors. With the azacalixphyrins, we enter also the field of coordination chemistry as ligands as indicated by preliminary studies. We can thus envision for these new dyes exceptional versatility by analogy to porphyrins.
Authors : Z. Chen, M. Giorgi, D. Jacquemin, M. Elhabiri and O. Siri Angew. Chem. Int. Ed., (2013), 52 : 6250–6254.