Photophysical properties of 2,6-dicyano-N,N,N ′,N ′-tetramethyl-p-phenylenediamine

Photophysical properties of 2,6-dicyano-N,N,N ′,N ′-tetramethyl-p  -phenylenediamine (DCTMPPD) are reported. Fluorescence quantum yields range from 0.37 to 0.58 and fluorescence lifetimes from 12.2 to 22.9 ns in 28 different solvents. The triplet energy is determined to be 16.8 kK. Steady-state and time-resolved emission anisotropies in glycerol are given. Three correlation times with τ1<0.8τ1<0.8  ns τ2=20τ2=20  ns and τ3>80τ3>80 ns are found. The fluorescence solvatochromism is analyzed using empirical one- and multiparameter approaches as well as classical non-empirical continuum models. The excited state dipole moment is estimated to be between 10 and 12 D, depending on the model applied. The ground state pKaKa is determined to be 2.5, while for the excited state pKa∗ a range of 0.5–2 can be estimated.