A computational study of truxene, isotruxene, and their pentagon- and hexagon-containing analogs. Polarizability evolution from polycyclic “subfullerene” hydrocarbons to C ₆₀

This brief study is our response to very recent work on the synthesis of truxene and isotruxene based on the indene cyclotrimerization. We complement this experimental study with our quantum-chemical computations with density-functional theory methodology. Using the PBE/3ζ method, we found the thermodynamic parameters of the competing reactions of truxene and isotruxene formation from indene and indanone-2 that demonstrate a higher possibility of the formation from the first precursor. Truxene is 17 kJ/mol more stable than its structural isomer and has a lower mean polarizability that indicates its higher stability toward further conversions. Further, we focus on the polarizability changes in the series of molecules from subfullerene polycyclic hydrocarbons (analogs of truxene) to C60. The mean polarizability in this series increases subadditively, i.e. it grows slower with increasing molecular size. We consider that this trend may be used for rationalizing the molecular components of astronomical objects, as mean polarizability is important for the survivability of the molecules under interstellar conditions.