Modeling of the interstellar medium optical absorption spectrum by primitive hybrid molecules C$_{24}$H$_{30}$, C$_{32}$H$_{36}$ and С$_{73}$Н$_{74}$

Accounting for the different contributions of the aromatic rings, separated with $sp^3$ bonds, with ab initio method we constructed the hybrid cluster С$_{73}$Н$_{74}$ which UV spectrum matches the most noticeable absorption band of 217.5 nm, known from astrophysical observations.