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

Anti-1,8-bisTPI-naphthalene in which two imidazole rings are constrained to an anti-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 anti-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.本研究成功合成反式-1,8-双TPI萘（Anti-1,8-bisTPI-naphthalene），该化合物的两个咪唑环（imidazole ring）被约束为反式构象，该构象对应桥联咪唑二聚体（bridged imidazole dimer）首次得到的1,4'-异构体。该自由基的颜色与此前报道的桥联咪唑自由基（bridged-imidazolyl radicals）存在显著差异，原因在于反式构象削弱了自由基间的分子内相互作用。该分子设计策略不失为一种有效的调控桥联咪唑二聚体自由基颜色的方案，有望应用于眼科镜片领域。