Luminescent, highly halogenated 2-(2-hydroxyphenyl)benzothiazole derivatives and their zinc complexes

Abstract

We have developed synthetic routes to new luminescent materials which are fully halogenated analogues of the zinc(II) complex of 2-(2-hydroxyphenyl)benzothiazole. 2,4-Difluoro-6-methoxybenzoyl chloride is a useful intermediate in this approach, which involves condensation with fluorinated arylamines to form the arylamide, cyclisation using P2S5, demethylation with BBr3 and halogenation to replace hydrogen atoms present on the phenolic ring. When 2-amino-1,3,4,5,6,7,8-heptafluoronaphthalene was used as the amine component the cyclisation step caused loss of F-1 in preference to F-3, and thus to the formation of the angular naphtho[2,1-d]thiazole ring system (confirmed by X-ray diffraction and NMR). The introduction of chlorine and bromine atoms at specific positions allows fine tuning of emission properties, compared with the analogous fully fluorinated materials.