Inorganic anions dependent orientation of ammonium cations in crown ether–ammonium cation–inorganic anion system

Five supramolecular assembly complexes: 2-hydroxypropane-1,3-diammonium-perchlorate-18-crown-6 ([C3H12N2O-(18-crown-6)2]2+·2[ClO4]−, 1); 2-hydroxypropane-1,3-diammonium-tetrafluoroborate-18-crown-6 ([(C3H12N2O)2-(18-crown-6)3]2+·2[BF4]−, 2); 4-methylanilinium perchlorate-18-crown-6 ([C7H10N-(18-crown-6)]+·[ClO4]−, 3); 4-iodineanilinium-tetrafluoroborate-18-crown-6 ([C6H7NI-(18-crown-6)]+·[BF4]−, 4); 4-methylanilinium tetrafluoroborate-18-crown-6 ([C7H10N-(18-crown-6)]+·[BF4]−, 5), for the investigation of the influence of different inorganic anions on the orientation of ammonium cation and host–guest interaction of crown ethers, have been synthesized and characterized. The results revealed that ClO4− anion lead to the 2:1 composition of crown and ammonium cation in monoclinic space group and 3:2 composition of crown and ammonium cation in the presence of BF4− anion for double-anilinium system (complexes 1 and 2). While for the single-anilinium system (complexes 3, 4, and 5), the different inorganic anions lead to quite different orientation of the ammoniums in orthorhombic space group. We also studied the TGA/DSC properties, Raman spectrascopy and hot stage microscopy for the five complexes.

Supramolecular assembly of crown ether with 2-hydroxypropane-1,3-diamino, 4-methylaniline and 4-iodoaniline in the presence of HClO4 and HBF4 have been prepared and characterized. The inorganic anions pay a key role in the construction of supramolecular architectures of crown ether–ammonium cation–inorganic anion system.Figure optionsDownload as PowerPoint slide