A compound comprising a tetrahalobenzamidazolebenzene or a bis(tetrahalophenyl)biphenylbisimidazole of the alternative following formulas or dimers thereof ##STR00001## wherein each of R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are the same or different and are independently selected from the group comprising hydrogen, alkyl, aryl, and halogen.