Heteroatom effect at C7 of norbornadiene-Quadricyclane system for maximizing the solar energy storage: DFT calculations

An attempt is made to maximize the solar energy storage in norbornadiene (1)/quadricyclane (2) system, through exchanging of heteroatoms at C₇ of 1 and 2; calculating the corresponding energies at MP2/6-311++G(3df,2p)//B3LYP/6-311++G(3df,2p) and B3LYP/6-311++G** levels of theory. Free energy gaps between 1 _X and 2 _X, δG_(1x)-(2x), and solar energy storage is the most for 1 _Se, 1 _As and 1 _Al from group VIII, VII and III of the Table, respectively.