Twisted Molecular Structure on Tuning Ultralong Organic Phosphorescence

Compared to planar carbazole, the molecular conjugation of iminodibenzyl (Id) was destroyed by a C-C bond and a twisted structure was formed, which exhibited blue-shifted ultralong phosphorescence with a lifetime of 402 ms in a crystal under ambient conditions. For the presence of an oscillating C-C bond between the two benzene rings in Id, more than one molecular configuration in the crystal was discovered by X-ray single-crystal analysis. Moreover, its ultralong phosphorescence color changed from blue to green by varying the excitation wavelength in solution at 77 K. Theoretical calculations also confirmed that different molecular configurations had certain impact on the phosphorescent photophysical properties. This result will allow a major step forward in expanding the scope of ultralong organic phosphorescent (UOP) materials, building a bridge to realize the relationship between molecular structure and UOP property.