Assembly modes in the solid state structure of the complexes of melamine mono-cations with para-calix[4]arene sulfonic acid and calix[4]arene dihydroxyphosphonic acid

Abstract

The crystal structures of the complexes between melamine mono-cations and para-calix[4]arene sulfonic acid and calix[4]arene dihydroxyphosphonic acid have been determined. In both cases the structure is based on a bilayer motif of calixarene molecules intercalated by motifs of melamine mono-cations. While in the complex with calix[4]arene dihydroxyphosphonic acid the motifs of melamine cations are parallel to the in-layer arrangement of the calixarene, for parasulfonatocalix[4]arene there is 17.61 displacement between the axes of the two motifs generating a laminate structure.

Breaking down the para-sulfonato-calix[4]arene bilayer motif into tapes and fences: the solid-state structure of the complex with 6-methoxyquinoline

“…Distances along the fence are 3.37 and 3.50 A ˚for the partially included molecule, then 3.64 and 3.59 A ˚and finally 3.46 and 3.36 A ˚, before repeating due to the symmetry. Thus we have alternating short and long p-p stackings, this was also observed for complexes of para-sulfonato-calix [4]arene with 8-hydroxyquinoline, 17 melamine, 18 1,10-phenanthroline, 19 and para-sulfonato-thiacalix[4]arene with 1,10-phenanthroline. 20 For comparison, in the reported recently 17 crystal structures of the complexes formed by para-sulfonato-calix [4]arene as a host with 8-hydroxyquinolinium and 8-aminoquinolinium cations, the organic cations form infinite chains (8-hydroxyquinolinium cations), or do not take part in any p-p interactions with other guest molecules (8-aminoquinolinium cations).…”

Solid-state interactions of calixarenes with biorelevant molecules

“…Complexes with L-lysine (28) and D-arginine (27) were reported by Coleman at al. 31,32 For L-lysine the 1 : 2 host : guest stoichiometry is observed with two guest molecules embedded within the host cavity and two more located between the molecular complexes.…”

“…Crystal structures with other amines, e.g. propanediamine, 51 benzimidazole, 2-hydroxybenzimidazole 26 and melamine 28 have also been reported, but as they are not biologically relevant, they are not described here.…”

“…29 Fig. 9 Bilayer-type structure of the para-sulfonatocalix [4]arene complex with L-lysine (28). 31 Fig.…”

Structure of the kanamycin–calix[4]arene di-O-phosphonate salt

“…16 Calix [4]arene diphosphonic acid has been shown to bind as an anion to a number of alkyl 18 and heterocyclic ammonium cations, 19 including the antiseptic chlorhexidine. 20 In all cases where complexation takes place from aqueous solvents the base structural motif is an interdigitated dimer. The packing motifs observed range from simple bilayer systems in the complex with melanine, 21 through cage structures seen with phenanthroline 22 to assemblies with aqua channels for the complex with the propane diammonium cation.…”