TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The alkali catalyst is anhydrous potassium carbonate, anhydrous sodium carbonate, anhydrous cesium fluoride, anhydrous potassium hydroxide or anhydrous sodium hydroxide, preferably anhydrous potassium carbonate. The sulfur-containing diphenol compound is 4,4'-dihydroxy diphenyl sulfide, 4,4'-dihydroxy diphenyl sulfone or 2,7-dihydroxy thianthrene, preferably 4,4'-dihydroxy diphenyl sulfide. The dimercapto compound is 1,4-dithiobenzene, 4,4'-dimercapto biphenyl, 4,4'-dimercapto diphenyl sulfide, 4,4'-dimercapto diphenyl sulfone or 2,7-dithio thianthrene, preferably 4,4'-dimercapto diphenyl sulfide. The molar ratio of 4-nitrobenzil to sulfur-containing diphenol compound or dimercapto compound is 2-2.5:1, preferably 2.1:1. The concentration of 4-nitrobenzil in the solvent is 5-30 wt.%, preferably 15-25 wt.%. The concentration of sulfur-containing diphenol compound or dimercapto compound is 5-30 wt.%, preferably 15-25 wt.%.n = 1-50, preferably 13.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of (II) comprises reacting 4-nitrobenzil and a sulfur-containing diphenol compound or dimercapto compound in a solvent in presence of an alkali catalyst. Preferred Components: The solvent is N-methyl pyrrolidone, 1,3-dimethyl imidazolone, N,N-dimethyl formamide, N,N-dimethylacetamide or dimethyl sulfoxide, preferably dimethyl sulfoxide. Preferred Method: The reaction temperature is 50-100 degrees C, preferably 60-80 degrees C. The reaction time is 10-30 hours, preferably 20-25 hours. Preferred Components: (III) is 3,3',4,4'-tetramino biphenyl, 3,3',4,4'-tetramino diphenyl ether, 3,3',4,4'-tetramino diphenyl sulfide, 3,3',4,4'-tetramino diphenylmethane or 3,3',4,4'-tetramino diphenyl sulfone. The solvent is N-methyl pyrrolidone, m-cresol or p-chlorophenol, preferably m-cresol. The molar ratio of (III) to (II) is 1-1.05:1, preferably 1:1. The concentration of the mass sum of (II) and (III) is 5-30 wt.% in the reaction system, preferably 20 wt.%. The thio-ether containing polyphenyl quinoxaline compound is a polyphenyl compound of formula (I) or (V).