Tert-alkylphenoxy-substituted polycyclic compounds of the general formula I ##STR00001## where P is a conjugated polycyclic radical which is stable to bases and nucleophiles, optionally bears aryl substituents and contains no group from the group consisting of --CO--NH--CO--, --COOH and --CO--O--CO--; R is C.sub.1 C.sub.8-alkyl, whose carbon chain may be interrupted by one or more groups selected from the group consisting of --O--, --S--, --NR.sup.1--, --CO-- and/or --SO.sub.2-- and which may be monosubstituted or polysubstituted by C.sub.1 C.sub.6-alkoxy or by a 5- to 7-membered heterocyclic radical which is attached via a nitrogen atom and may contain further heteroatoms and be aromatic; C.sub.5 C.sub.8-cycloalkyl whose carbon chain may be interrupted by one or more groups selected from the group consisting of --O--, --S--, --NR.sup.1--, --CO-- and/or --SO.sub.2-- and which may be monosubstituted or polysubstituted by C.sub.1 C.sub.6-alkyl; R.sup.1 is hydrogen or C.sub.1 C.sub.6-alkyl; Hal is chlorine and/or bromine; m is from 0 to 15; n is from 1 to 16, subject to the proviso that the sum m+n is .ltoreq.16, are prepared and used.