Synthesis and characterization of solution processable 6,11-dialkynyl substituted indeno[1,2-b]anthracenes

Twelve indene-fused dialkynyl substituted anthracene derivatives (indenoanthracenes) were synthesized and their optical, electrochemical and thermal properties were described. These small molecules possess high quantum yields, thermal and photoxidative stabilities, and solubility in common organic solvents. Indenoanthracenes (57-92%) were prepared in two steps from four different indenoanthraquinones obtained via a highly selective and practical benzocyclobutendione based methodology. The photophysical properties of indenoanthracenes were investigated by UV-vis and fluorescence spectroscopies. From spectroscopic data of indenoanthracenes, quantum yields (Φ, 0.28-0.71) and optical HOMO-LUMO energy gaps were determined. Electrochemistry of indenoanthracenes was studied and electrochemical HOMO-LUMO energy gaps were also determined from the onset oxidation and reduction potentials. Density functional theory calculations were performed to obtain the geometry optimized structures and HOMO-LUMO energy levels. Fluorenylethynyl substituted indenoanthracene was employed as an emitting layer in a solution processed OLED device and the maximum current efficiency and luminance were found to be 1.02 cd/A and 1284 cd/m², respectively.