18-crown-6 ether complexes with aralkylammonium perchlorates

摘要: Thermochemical properties of crown ether complexes have been studied by simultaneous TG-DTA (thermogravimetric analysis-differential thermal analysis) coupled with a mass spectrometer, DSC (differential scanning calorimetry) and hot stage microscopy (HSM). The examined contain benzylammonium- [BA], (R)-(+)-a-phenylethylammonium- [(R)-PEA], (R)-(+)- (S)-(-)-a-(1-naphthyl)ethylammonium perchlorate [(R)-NEA (S)-NEA] salts as guests. In the cases BA (R)-PEA an achiral pyridono-18-crown-6 ligand [P18C6], in case (R)-NEA (S)-NEA chiral (R,R)-dimethylphenazino-18-crown-6 [(R,R)-DMPh18C6] was used host molecule to obtain four different complexes. all cases, melting points were higher than those both guest compounds. decomposition begins immediately after their is completed, while ligands are thermally stable 50 100 K above points. During strongly exothermic processes can be observed which due oxidative reactions anion. Ammonium crystals identified among residues salts. P18C6 crystallize two molecules water. did not any solvate. exhibit reversible solid-solid phase transition upon heating. heterochiral complex consisting (R,R)-DMPh18C6 shows followed HSM observations three crystal modifications, them simultaneously co-existing.