Synthesis and characterization of heteroatom-bridged bisspirobifluorenes for the application of organic light-emitting diodes

Pure 2-iodo-9,9′-spirobifluorene was synthesized by an efficient method without troublesome iodination of 9,9- spirobifluorene (SP) or the Sandmeyer reaction of 2-amino-9,9′-spirobifluorene. A series of main group element-bridged bis-9,9′-spirobifluorene derivatives were synthesized via coupling reactions of 2-iodo-9,9′-spirobifluorene and main group element-containing precursors. These heteroatom-bridged bis-spirobifluorenes show large triplet state energy gaps, high glass transition temperatures, and varied charge-transporting properties advantageous to the host materials for blue phosphorescence organic light-emitting diodes (PhOLEDs).