Spectroscopic characteristics of a novel highly fluorescent p-phenylenediamine: Tetracyano-p-phenylenediamine

We present here some of the physicochemical properties of tetracyano-p-phenylenediamine (TCPPD). This is the second highly fluorescent p-phenylenediamine (PPD) presented in the literature. The molecule emits with a very long lifetime (20 ns) and an oxygen insensitive high quantum yield (up to 0.9) for this class of molecules. Its emission peak is located in the range of 540–630 nm depending on the solvent. Both, absorption and fluorescence solvatochromism are mainly controlled by the solvent basicity parameter, β, which makes this molecule unique. Despite the electrochemical characteristics of other members of the PPD family, TCPPD can be reversibly reduced (−0.72 V vs SCE) but not oxidized. These properties make TCPPD a very interesting candidate for several applications in fluorescence sensing, or as building block for n-type conducting polymers for solar cells, organic transistors or OLED devices.