Synthesis and properties of (1,2,3,7,9-pentamethyldipyrrolylmethen-8-yl)-(1,2,3,7,8-pentamethyldipyrrolylmethen-9-yl)methane and bis(1,2,3,7,9-pentamethyldipyrrolylmethen-8-yl)trifluoromethylmethane dihydrobromides