Substitution effects in biphenyl linked fullerene dimer systems

Abstract

On the purpose of bringing out a new kind of fullerene dimers, several properties of biphenyl connected fullerene dimer systems are presented. We report molecular mechanics (MM+) optimizations with semi-empirical MNDO single point energies used to evaluate the effect of four different substitutions on the biphenyl ring, for 6 different species. The steric effects are obvious when the substituent becomes bulky since the smallest differences are seen for the halide systems, while the largest is for tributyl substitution (-C(CH3)(3)) on the ring. The electron withdrawing groups can lower down the heat of formation by some extent and -OCF3 is expected to be the best group to facilitate the formation of the dimer.