Four heterocyclic hexaarylbiimidazoles, BFuTM-HABI, BThTM-HABI, BCTFu-HABI, and BCTTh-HABI, were synthesized to improve the UV-vis absorption properties of hexaarylbiimiclazoles. UV-vis spectra, fluorescence spectra, ESR measurements, photo-dilatometer experiments, and photo-DSC measurements indicate that BCTFuHABI and BCTTh-HABI exhibit better UV-vis absorption abilities and photoinitiation activities for acrylate derivatives with different functionalities than BFuTM-HABI and BThTM-HABI, respectively. (c) 2007 Wiley Periodicals, Inc.