Ring-Opened Hemiporphyrazines: Helical Molecules Exhibiting Circularly Polarized Luminescence.

We designed and synthesized a new type of small helical molecule exhibiting intense circularly polarized luminescence (CPL) (12H ) by modifying a 20π-electron hemiporphyrazine with a large transition magnetic dipole moment. The hemiporphyrazine ring was opened and one additional pyridine unit was introduced, resulting in an overlap of two pyridine rings. X-ray structure analysis confirmed that 12H and its zinc complex (1Zn ) adopt a helical geometry. A racemic mixture of 1Zn was resolved into two enantiomers ((P)- and (M)-1Zn ), which exhibited CPL with a high luminescence dissymmetry factor (glum ) value of ±2.1×10-2 . The origin of the large glum value was rationalized by means of DFT calculations. Helical structures could be formed in a diastereoselective manner by covalently attaching chiral units to the skeleton (1'2H and 1'Zn ). 1Zn was found to possess chiral recognition ability for amines.