Density functional theory studies on the Diels–Alder reaction of [3]dendralene with C60: an attractive approach for functionalization of fullerene

The Diels–Alder reaction between C60 and [3]dendralene has been carried out using density functional theory based Becke’s three-parameter hybrid exchange functional and Lee–Yang–Parr correlation functional (B3LYP) method with 6−31G* basis set. The importance of dispersion corrections has been assessed by performing calculation at dispersion corrected B2PLYP-D/6–31G* level. The results reveal that the fullerene can be functionalized using [3]dendralenes. Several new types of adducts viz. mono (1), bis (1–1′ and 1–2), tris (1–1′–2 and 1–2–1′), tetrakis (1–1′–2–2′), pentakis (1–1′–2–2′–3), and hexakis (1–1′–2–2′–3–3′) can be formed by the stepwise addition of [3]dendralene due to its multifarious reactive sites. Furthermore, it is observed that the 1–2 additions are thermodynamically and kinetically more feasible than the 1–1′ ones. The geometrical distortion energy (Edis) exhibits a linear relationship with the corresponding reaction barrier heights. The HOMO and LUMO energies of various reactants elicit that DA reaction is driven by normal electron demand. It is interesting to note from the energy decomposition analysis that although the steric effects dominate the addition reaction, the dispersion interaction plays a significant role in the stabilization of transition states. It is evident from the density of state and HOMO–LUMO gap (Egap) that the functionalization of C60 by [3]dendralene marginally alters the conductivity.