Push–pull derivatives based on CF3-substituted pyrimidines as solvatofluorochromic materials for OLEDs

Abstract

A series of push–pull fluorophores based on CF₃-substituted pyrimidines was synthesized and investigated using spectroscopic measurements and quantum chemical calculations. First-generation OLEDs were fabricated using these push–pull systems as emitters, exhibiting emission maxima in the blue region (464–477 nm) and varying performance. The compounds exhibited strong positive solvatofluorochromism. TD-DFT calculations at the MN15/6-31G(d,p) level of theory revealed the rotational flexibility of the dimethylamino group in these systems. The wavelength and oscillator strength of the S₀ → S₁ transition in push–pull fluorophores are highly sensitive to the rotation of the dimethylamino group. Due to the rotational flexibility of the dimethylamino group, the observed spectral and luminescent properties likely arise from a combination of different conformations and are affected by environmental conditions.