The colorimetric detection of anionic species has been studied for a-amino acid-conjugated poly(phenylacetylene)s, which were prepared by the polymerization of the ethyl esters of N-(4-ethynylphenylsulfonyl)-L-alanine, L-isoleueine, L-valine, L-phenylalanine, L-aspartic acid, and L-glutamic acid using Rh+(2,5-norbornadiene)[(eta(6)-C6H5)B-(C6H5)(3)) as the catalyst in CHCl3. The one-handed helical conformations of all the sulfonamide-functionalized polymers were characterized by Cotton effects in the circular dichroism spectra. The addition of anions with a relatively high basicity, such as tetra-n-butylammonium acetate and fluoride, induced drastic changes in both the optical and chiroptical properties. On the other hand, anions with a relatively low basicity, such as tetra-n-butylammonium nitrate, azide, and bromide, had essentially no effects on the helical conformation of all the sulfonamide-functionalized polymers. The anion signaling property of the sulfonamide-functionalized polymers possessing a-amino acid moieties was significantly affected by the installed residual amino acid structures. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1683-1689, 2010