Hydrogen-bonded assemblies of a series of thiourea derivatives of sulfa-drugs, 4-(3-arylthioureido)-N-(thiazol-2(3H)-ylidene) benzenesulfonamide (aryl = phenyl, 4-methoxyphenyl, 4-nitrophenyl, 2,3or 2,4-or 3,4-dichlorophenyl), and their polymorphs and solvates were investigated. All forms of the 4-(3-arylthioureido)-N-(thiazol-2(3H)ylidene)benzenesulfonamides studied here, other than a dimethyl sulfoxide (1:2) solvate, had homodimeric hydrogen-bonded units. The 4-(3-phenylthioureido)-N-(thiazol-2(3H)-ylidene)benzenesulfonamide provided two polymorphs, one having a hairpinlike structure and other a stretched structure. The projections of the −SO 2 − groups in the respective homodimer as well as the orientations of the thiourea part of the polymorphs were different. In the respective self-assembly, 2,3-or 2,4-or 3,4-dichlorophenylthiourea derivatives of sulfathiazole (positional isomers), the types of chlorine-chlorine interactions were dependent on the position of chloro groups on the phenyl ring. The theoretically calculated energy of the homodimers of the positional isomers had showed a predictable trend in the melting point in the respective series. The dimethylformamide hydrate as well as the dimethylacetamide solvate of N-(4,6-dimethylpyrimidin-2(1H)-ylidene)-4-(3-(4-nitrophenyl)thioureido)benzenesulfonamide had similar unit cell dimensions. This fact shows that the water molecule in the former case had compensated the space in the lattice required for an additional methyl group present in the dimethylacetamide than the dimethylformamide to achieve tight packing. The 4-nitrophenylthiourea derived compounds could selectively detect fluoride ions by visual means.