Synthesis, X-ray crystal structure, and optical properties of novel 9,9-diethyl-1,2-diaryl-1,9-dihydrofluoreno[2,3-d]imidazoles

Abstract

A series of 9,9-diethyl-1,2-diaryl-1,9-dihydrofluoreno[2,3-d]imidazole derivatives were conveniently synthesized by condensation of the key intermediate N 2-aryl-9,9-diethyl-9H-fluorene-2,3-diamine with aldehydes under very mild conditions with good yields. The entire target compounds were characterized using 1H NMR spectroscopy, 13C NMR spectroscopy, high resolution MS, optical absorption, and emission spectra. The crystal structure of 2-(4-bromophenyl)-9,9-diethyl-1-phenyl-1,9-dihydrofluoreno[2,3-d]imidazole was determined as monoclinic, space group P2 1 /c type, using single X-ray crystallography. Most compounds possess medium fluorescence-emitting ability with Φ FL values in the region of 0.40–0.84 and displayed different emission within 379–425 nm in CH2Cl2 depending on the nature of the whole molecule.