Synthesis And Characterization Of Indenofluorenes, Fluorene-and Spirobifluorene-fused Thiophenes

Organic light-emitting diodes (Organic Light-mitting Diode, OLED) recently attracted numerous attention due to their excellent optical properties. The related organic molecules suitable for OLED device fabrication is becoming one of the hottest research fields. This dissertation consists of two sections:indeno-fluorene derivatives (including isotruxenes) and fluorene-and spirobifluorene-fused thiophenes. We present the synthetic approaches of foresaid compounds and the primary investigation on their properties.In the first part, the Diels-Alder reaction of methyl propiolate with indanocyclone (2,8-dioxo-1,3-diphenyl-2,8-dihydrocyclopenta[a]indene) led to the formation of two isomers, which were hydrolyzed to form related acids. Then the Friedel-Crafts acylation was employed to form indenofluorenone. Reduction of the carbonyl groups was completed by Wolff-Kishner-Huang reaction. And ethyl groups were then introduced on methylene linkage to form the tetraethyl-indenofluorenes via lithium-halogen exchanges; The reaction of indeno-fluorenones with lithium salt of4,4’-di-tert-butyl-2-bromobiphenyl prepared in situ to form the tertiary alcohols, which were subsequently converted into dispirobifluorenes by acid-promoted ring closures. These series of derivatives show the excellent optical properties and high fluorescence quantum efficiency from their UV and the fluorescene spectra. Furthermore, two novel isotruxene derivatives with5-position substituted to make up for the blank of the corresponding fields were obtained by well-defined synthetic routes.In the second part, the Dields-Alder reaction of1,4-dihydroxy-2-butyne with indanocyclone resulted in the formation of1,4-diphenyl-2,3-bis(hydroxymethyl)fluorenone, which was converted stepwise into1,4-diphenyl-2,3-bis(bromomethyl)-intermediates of fluorene, fluorenone, spirobifluorene and9,9-diethylfluorene. The reaction between foresaid bis(bromomethyl)-intermediates and Na2S.9H2O in the mixture of tetrahydrofuran and ethanol led to the formation of2,5-dihydrobenzo[c]isothiophenes, which were dehydrogenized over palladium on charcoal to form fluorene-and spirobifluorene-fused thiophenes. The UV spectra and the FL spectra of fluorene-and spirobifluorene-fused thiophenes revealed that they might be used as precursors for blue emission materials.