Tetrabutylammonium fluoride (TBAF) forms cocrystal H₂NAP·TBAF with 2-hydroxynaphthaldoxime (H₂NAP) or cocrystal 2(H₃OHPA)·TBAF with 2,3-dihydroxyphenylaldoxime (H₃OHPA), whereas a similar reaction with 2,4-dihydroxyphenylaldoxime (H₃PHPA) forms tetrabutylammonium (TBA) salt TBA(H_2.5PHPA)₂. Formation of these cocrystals or salts is accompanied by a color change which enables the detection of fluoride ions. Cocrystal H₂NAP·TBAF has a layered structure formed by hydrogen bonds between the fluoride ions and parent oxime molecules; the tetrabutylammonium cations are held in between layers of anionic assemblies. On the other hand, cocrystal 2(H₃OHPA)·TBAF has a grid-like architecture constructed from hydrogen bonds between the parent oxime molecules and fluoride ions. TBA cations are encapsulated within the grids. It is shown that salt TBA(H_2.5PHPA)₂ forms anionic assemblies to encapsulate tetrabutylammonium cations which are devoid of fluoride ions. By interactions of the tetrabutylammonium fluoride ions with H₃PHPA molecules, an anionic assembly is formed by the sharing of protons, which possesses a grid-like structure. The formation of such an assembly causes color change which enables one to detect fluoride ions by visual means.