Synthesis, Structure and Photophysics of Neutral π-Associated [2]Catenanes

Three neutral π-associated [2]catenanes have been synthesised from the oxidative dimerisation of terminal acetylene-equipped electron-deficient diimides in the presence of an electron-rich dinaptho-crown template (below). The mutual recognition of the complementary donor–acceptor building blocks is revealed in solid-state analyses of a precatenane inclusion complex and a [2]catenane. Dynamic movement of the interlocked rings has been examined by 1H NMR spectroscopy, and a model has been developed to explain the observed photophysics.