A new series of poly(ortho-phenylazonaphthol) derivatives linked with a phenylene or fluorene repeat unit was synthesized using the Suzuki cross-coupling reaction and characterized. The synthesized polymers can be categorized by their structures, with a free hydroxyl group and with a t-Boc-blocked hydroxyl group, which exhibited completely different UV-vis absorption properties according to the allowed or forbidden tautomerism. In both cases, a pronounced color change to deep violet (bathochromic shift) was induced upon exposure to fluoride anion, presumably because of electron transfer between the hydroxyl group and the fluoride anion. Interestingly, the chromogenic pattern could be produced directly by UV irradiation through a photomask on the flexible nanofiber web electrospun from poly(methyl methacrylate) blended with t-Boc-protected Polymer 8 and photoinduced acid generator. (c) 2007 Wiley Periodicals, Inc.