Two novel violurate and squarate salts of cinchonine – Structures and physical properties

The correlation between the structural and the physical properties in solid state of two novel salts of cinchonine, cinchoninium violurate monohydrate (1) and cinchoninium squarate tetrahydrate (2), has been studied in dependence on protonation mode, using the methods of single crystal X-ray diffraction, IR-LD spectroscopy of oriented samples as a suspension in nematic liquid crystals, UV–vis spectroscopy and 1H and 13C NMR spectroscopy. HPLC tandem mass spectrometry (HPLC ESI MS/MS) and thermal methods were also employed. Quantum chemical calculations have been performed with a view to obtaining the physical properties of the cinchoninium mono- and di-cation.