A new, longest, stable, green twisted heteroacene 2-methyl-1,4,6,13-tetraphenyl-7:8,11:12-bisbenzo-anthro[g]isoquinolin-3(2H)-one (3) was synthesized by employing a “clean reaction” strategy based on thermally eliminating lactam bridges. Calculation shows that the HOMO–LUMO bandgap is in good agreement with experimental data.