Porphyrinoids in which one or two pyrrole rings are replaced with polycyclic aromatic hydrocarbons/heterocycles such as naphthalene, phenanthrene, biphenyl, bipyridine, or phenanthroline are a new class of porphyrinoids represented as polycyclic aromatic hydrocarbon (PAH)‐/heterocycle‐embedded porphyrinoids. These macrocycles possess the structural features of both polycyclic aromatic hydrocarbons/heterocycles and cyclic polypyrrolic porphyrinoids. The PAH‐embedded porphyrinoids have drawn significant interest in recent times because of the following: (1) these macrocycles exhibit different π‐conjugation pathways unlike porphyrinoids, which exhibit circular conjugation pathways in their macrocyclic rings with various molecular structures; (2) the PAHs embedded macrocycles show variable degree of aromaticity which varies from weak aromaticity to antiaromaticity and (3) the PAHs embedded porphyrinoids provide unique ligand environment to form stable coordination and organometallic complexes in which metals may show uncommon oxidation states and unusual reactivity. All these above‐listed features depend on polycyclic aromatic hydrocarbon/heterocycle moiety present as a part of porphyrinoid macrocyclic framework. This Minireview focuses on the synthesis of different polycyclic aromatic hydrocarbon‐/heterocycle‐embedded porphyrins, contracted porphyrins and expanded porphyrins and briefly discusses their structural, spectral, aromatic and coordination properties.

meso-Tetraphenyl meta-benziporphyrins are nonaromatic macrocycles which can be changed to antiaromatic by fusing the core benzene ring with one of the adjacent meso-phenyl groups, as demonstrated here by adopting a premodification method. We used a fluorene moiety in place of the m-phenylene ring as a premodified fused aromatic motif to synthesize fused heterobenziporphyrins. Spectral and X-ray data indicated that the macrocycles are antiaromatic, which was supported by DFT, ACID, and NICS calculations. These macrocycles formed organopalladium complexes.

Small molecular fluorophores with high quantum yields are of particular interest because of their role in several applications that range from ion sensing to bioimaging. Indole based biomolecules are well known for their fluorescence properties. Pyrrolo[1,2-a]indoles have gained tremendous interest in recent times due to their applicability in various fields such as biomedicine and dye-sensitized solar cells (DSSC). In this article, we report the synthesis of new types of crowned 3H-pyrrolo[1,2-a]indole fluorophore macrocycles 1-3 which were prepared in 30-35% yields using commercially available compounds under simple reaction conditions. These fluorophore macrocycles 1-3 were charac-terized by HR-MS, 1D & 2D NMR, X-ray crystallography, absorption, fluorescence, electrochemical, and DFT/TD-DFT studies. The fluorophores 1-3 absorb in the region of 465-480 nm and emit in the region of 615-645 nm with large Stokes shift (~150 nm), 10-20% quantum yields, and singlet state lifetimes of 1.70-2.50 ns. The electrochemical studies revealed that macrocycles 1-3 are electron-rich and undergo easier oxidations. The macrocycles 1-3 readily form cation radicals by chemical and electrochemical oxidation which are highly stable at low temperatures as well as at room temperature.