Abstract
In the field of chemical biology and/or supramolecular chemistry, fluorescein (1) had made great contributions as a mother skeleton of useful and sensitive fluorescent probe. However, naphtofluorescein, in which each one unit of benzene ring is expanded to the both sides of fluorescein, has received little attention. Only naphthofluorescein 2 is the single known example. Against such background, we constructed the novel naphthofluoresceins including linear derivative 3. The fluorescence spectra of 1-3 in basic aqueous medium were measured. Fluorescein (1) and 2 exhibited peak at 511 nm and 656 nm, respectively. On the other hand, 3 showed emission in near-infrared region at around 768 nm.
