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Accommodation of various organic molecules into a one-dimensional nanochannel of tris(ethylenediamine) cobalt(III) chloride, [Co(en)3]Cl3, anhydrated racemic crystal was examined using weight increment measurements, thermogravimetric–differential thermal analysis (TG–DTA), powder X-ray diffraction (PXRD) and 13C cross-polarization/magic angle sample spinning (CP/MAS) NMR techniques. Results showed that the (±)-[Co(en)3]Cl3 ionic crystal accommodates n-alkanes, n-alkylalcohols, n-alkylamines, and acetonitrile in the 1D nanochannel without decomposition of the crystal lattice. The guest molecules are in all-trans conformation in the nanochannel. Furthermore, the activation energies of uni-axial molecular reorientation of n-alkanes and n-alkylalcohols in the nanochannel were determined using temperature dependence of the 1H spin–lattice relaxation time in the rotating frame (T1ρ). Results demonstrated that the activation energy per CH2 unit (6.5 kJ mol−1) in n-alkylalcohols was twice that in n-alkanes (3.3 kJ mol−1), implying the possibility of dimer formation of n-alkylalcohols in the nanochannel by hydrogen bonding through OH group. These findings strongly suggest that the (±)-[Co(en)3]Cl3 ionic crystal has adsorption ability to various organic molecules. It will open new avenues to explore new types of zeolites that include ionic crystals. |
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