The title compounds, dimethylammonium 2-{4-[1-(4-carboxymethoxyphenyl)-1-methylethyl]phenoxy}acetate, C(2)H(8)N(+).C(19)H(19)O(6)(-), (I), and 2,2'-[isopropylidenebis(p-phenyleneoxy)]diacetic acid-4,4'-bipyridine (1/1), C(19)H(20)O(6).C(10)H(8)N(2), (II), are 1:1 adducts of 2,2'-[isopropylidenebis(p-phenyleneoxy)]diacetic acid (H(2)L) with dimethylammonium or 4,4'-bipyridine. The component ions in (I) are linked by N-H...O, O-H...O and C-H...O hydrogen bonds into continuous two-dimensional layers parallel to the (001) plane. Adjacent layers are stacked via C-H...O hydrogen bonds into a three-dimensional network with an -ABAB- alternation of the two-dimensional layers. In (II), two H(2)L molecules, one bipy molecule and two half bipy molecules are linked by O-H...N hydrogen bonds into one-dimensional chains and rectanglar-shaped rings. They are assembled via pi-pi stacking interactions and C-H...O hydrogen bonds into an intriguing zero-dimensional plus one-dimensional poly(pseudo)rotaxane motif.