Optoelectronic materials are provided that are bistable organic tautomeric compositions that intraconvert dithio or diseleno carbamate esters and cyclic 1,3-dithia- or -diselena-2-iminium salts of .pi.-conjugated bis-anthracenyl compounds. Specifically disclosed are compounds having the formula: ##STR00001## where X is sulfur or selenium; where the R and R.sub.1 groups are alkyl or alkyl that together form a ring of carbon atoms; where A.sub.n is the anion of a strong acid; and where the Z element is a chiral ring-completing system of atoms that changes chirality on tautomerization. These molecules are in themselves molecular-sized optoelectronic switching devices.