Trioxazolo[2(3)]metacyclophane: synthesis, structural analysis, and optical properties

The synthesis and characterization of the conjugated macrocycle trioxazolo[2(3)]-metacyclophane, C27H15N3O3 (M), is reported. The macrocycle was synthesized in three steps by the multicomponent van Leusen reaction and consists of meta-linked phenylenes connected through positions 4 and 5 of an oxazole heterocyclic ring. The molecular structure was investigated by NMR spectroscopy, mass spectrometry, gel permeation chromatography (GPC), and single-crystal X-ray crystallography. X-ray diffraction (XRD) analysis shows that M possesses a twisted saddle-like shape and interacts with nearby molecules by various pi-pi interactions. Absorption and emission spectroscopy and density functional theory (DFT) calculations were further used to study the electronic properties of M.