Incorporation of sulfonate dyes into hydrogen-bonded networks

Abstract

The reaction of [C(NH₂)₃]Cl with methyl orange, Na[O₃SC₆H₄NNC₆H₄NMe₂], leads to formation of [C(NH₂)₃][O₃SC₆H₄NNC₆H₄NMe₂] 1 in which the sulfonate dye has been incorporated into a guanidinium sulfonate hydrogen-bonded bilayer sheet structure. Similar reactions with substituted guanidinium cations give [C(NH₂)₂(NHMe)][O₃SC₆H₄NNC₆H₄NMe₂]·MeOH 2·MeOH, [C(NH₂)₂(NHEt)][O₃SC₆H₄NNC₆H₄NMe₂] 3 and [C(NH₂)₂(NMe₂)][O₃SC₆H₄NNC₆H₄NMe₂] 4. Although substitution disrupts formation of the GS sheets, the gross structures of 2–4 all have pseudo-bilayer structures, with similar gross features to 1. Compound 1 reacts with HCl in solution to generate the zwitterionic compound O₃SC₆H₄NHNC₆H₄NMe₂5, but solid samples of 1 react reversibly with HCl gas to give the HCl adduct 1a. This interconversion has been studied by powder X-ray diffraction, IR spectroscopy and diffuse reflectance visible spectroscopy.