“…Conversely, PAH compounds are also building blocks in natural products [ 2 ] (e.g., fluorene [ 3 , 4 ], phenanthrene [ 5 , 6 ], anthracene [ 7 , 8 ], and phenanthridine [ 9 , 10 ]), possess molecular properties that qualify their application in optoelectronic devices (e.g., organic solar cells [ 11 , 12 ]), find applications in other technologies [ 13 , 14 , 15 , 16 ], or are subject of toxicological investigations. Their heterocyclic ( N - and O -containing) derivatives (N-PAH/O-PAH) are especially attractive synthons in the pharmaceutical industries as part of active pharmaceutical ingredients (APIs) [ 17 , 18 , 19 ].…”