The synthesis of two new chlorinated fluorescein probes with a spacer linker arm, 4',5'-dichloro- 6-(5-carboxypentylaminocarbonyl)?uorescein and 2',7'-dichloro-6-(5-carboxypentylaminocarbonyl)?uores- cein was studied. The title compounds were prepared using chlororesorcinol and trimellitic anhydride as the starting materials in seven steps, with fine overall yields. The measurement of the fluorescence indicated that the title compounds possessed high quantum yields, and the λex and λem exhibited obvious red-shifts com-pared with fluorescein. The structures of the products were characterized by 1H NMR, IR, MALDI-TOF MS, and elemental analyses.

Key words: ?uorescein, fluorescent probe, synthesis