Novel 4,5-di(het)aryl-substituted 2-(N,N-di(het)arylamino)-thiazole derivatives of general structure (a), whereby the following applies: R.sup.1, R.sup.2and R.sup.3 and R.sup.4, independent of one another, are each a monofunctional (het)aryl system; R.sup.1 can additionally be a corresponding bifunctional (het)arylene system; R.sup.3 can additional signify R.sup.7, whereby R.sup.7 represents a chemical bond or a bifunctional (het)arylene system, or R.sup.3 can be one of the following groupings (b) and (c); R.sup.7 represents a chemical bond or a bifunctional (het)arylene system, and; R.sup.4 can also be H or (d).