A new family of non-planar heterocyclic molecules consisting of carbazoles was created. A bowl-shaped cyclodimer, a flake-shaped cyclotrimer, a double-decker-ring-shaped cyclotetramer and a cyclohexamer were synthesized by Ni0-mediated one-shot cyclo-oligomerization of 1,8-dibromocarbazole, and were named [n]cyclo-1,8-carbazolylenes (n=3,4,6). Cyclo-1,8-carbazolylene was found to act as a trivalent tridentate ligand for heteroatoms (B, P, Si), giving flake-shaped complexes. The boron derivative acted as a Lewis acid, and the tetra-coordinated complexes showed an unprecedented red-shift of absorption and emission spectra by the coordination. The synthetic method, the distorted C2 or C1 symmetric shape, the trivalent tridentate coordination ability and the kinds of introduced heteroatoms of cyclo-1,8-carbazolylenes, the electronic structure, the photophysical property, and the Lewis acidity were distinct from those of related subporphyrins/subphthalocyanines.
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