Structural study of six cycloalkyl-ammonium cinnamate salt structures featuring one-dimensional columns and two-dimensional hydrogen-bonded networks

Six ammonium carboxyl-ate salts, namely cyclo-pentyl-ammonium cinnamate, C₅H₁₂N⁺·C₉H₇O ₂^-, (I), cyclo-hexyl-ammonium cinnamate, C6H14N ⁺·C₉H₇O₂^-, (II), cyclo-heptyl-ammonium cinnamate form I, C₇H₁₆N ⁺·C₉H₇O₂^-, (IIIa), and form II, (IIIb), cyclo-octylammonium cinnamate, C₈H ₁₈N⁺·C₉H₇O₂ ^-, (IV), and cyclo-dodecyl-ammonium cinnamate, C₁₂H ₂₆N⁺·C₉H₇O₂ ^-, (V), are reported. Salts (II)-(V) all have a 1:1 ratio of cation to anion and feature three N⁺ - H⋯O^- hydrogen bonds forming one-dimensional hydrogen-bonded columns consisting of repeat-ing R ₄³(10) rings, while salt (I) has a two-dimensional network made up of alternating R₄⁴(12) and R⁶ ₈(20) rings. Salt (III) consists of two polymorphic forms, viz. form I having Z′ = 1 and form II with Z′ = 2. The latter polymorph has disorder of the cyclo-heptane rings in the two cations, as well as whole-mol-ecule disorder of one of the cinnamate anions. A similar, but ordered, Z′ = 2 structure is seen in salt (IV).