Y. Segawa, H. Omachi, K. Itami
Org. Lett. 2010, ASAP. DOI: 10.1021/ol1006168
The structures and strain energies of cycloparaphenylenes (CPPs) have been determined by DFT calculation at the B3LYP/6-31G(d) level of theory. Fifteen stable conformations of CPP were found as local minimum structures. It was also found that benzene rings of CPP can rotate rather freely at room temperature. The strain energies of [n]CPP (n = 6−20) were estimated on the basis of the homodesmotic reaction using CPP, biphenyl, and p-terphenyl. It was also found that CPPs have higher strain energy in comparison to cycloparaphenyleneacetylenes (CPPAs).