Synthesis and Properties of Cyclic (5)meta-Phenyleneacetylene and Its Corresponding Cyclophane Polyone, (25)(1,3)Cyclophanedecaone

The cyclic [5]meta-phenyleneacetylene (3) ([5]CMPA) and its corresponding cyclophane polyones 4 and 5 are synthesized. 3, a "missing link" between [4]CMPA and [6]CMPA, shows a fairly pronounced emission, indicating a rigid structure, whereas 5 is colorless in contrast to conventional diarylethane-1,2-diones owing to its conformational mobility and all-s-cis and twisted dione structure.