New fluorene derivatives based on 3,9-dihydrofluoreno[3,2-d]imidazole (FI): Characterization and influence of substituents on photoluminescence

2,3-Diamino-9,9-dioctylfluorene (DADOF), as a new multifunctional intermediate for π conjugated molecules, was efficiently synthesized via a seven-step procedure with an overall yield of 30%. Novel 9,9-dihydro-9,9-dioctyl-2-phenylfluoreno[3,2-d]imidazole (DOFIPh)-type fluorophores with polar substituents were designed and conveniently synthesized from DADOF, and their absorption and fluorescence properties were investigated in solution and in the solid state. The fluorophore DOFIPh exhibits strong blue emission in solid state and fine-tuning of the emission is possible depending on the electronic nature of the substituents.