Photochromism of a Naphthalene-Bridged Imidazole Dimer Constrained to the “<i>Anti</i>” Conformation

<i>Anti</i>-1,8-bisTPI-naphthalene in which two imidazole rings are constrained to an <i>anti</i>-conformation leading to the first-formed 1,4′-isomer of the bridged imidazole dimer has been synthesized. The color of the radicals is different from that of the previously reported bridged-imidazolyl radicals because the intramolecular interaction between the radicals becomes weak due to the <i>anti</i>-conformation. This molecular design would be a profitable strategy to control the color of the radicals of the bridged imidazole dimer for application in ophthalmic lenses