ABSTRACT
In its crystalline state, a dinuclear Cu-based metallocycle discriminates between the three isomers of xylene with liquid-phase selectivity in the order p-xylene â« m-xylene â« o-xylene. This selectivity holds over a wide concentration range, with p-xylene concentrations as low as 5%. Single-crystal X-ray diffraction and gas chromatography further indicate that the metallocyclic host extracts trace amounts of p-xylene from commercially pure o-xylene (≥99%); using NMR spectroscopy, we show that the metallocycle exhibits exclusive selectivity for p-xylene. Crystallographic studies show that the selectivity is based on the size and shape of the guest in combination with the flexibility of the host.
Subject(s)
Coordination Complexes/chemistry , Xylenes/isolation & purification , Adsorption , Copper/chemistry , Xylenes/chemistryABSTRACT
Guest molecules have been absorbed into crystals of a metallocyclic host by sublimation of volatile solids at room temperature. The guest exchanges are accompanied by color changes. Since the crystals remain intact, evidence of guest inclusion could be obtained using single-crystal X-ray diffraction. The results are also supported by thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible spectroscopy (UV-vis).
ABSTRACT
The liquid-phase epitaxy (LPE) method was effectively implemented to deliberately grow/construct ultrathin (0.5-1 µm) continuous and defect-free ZIF-8 membranes. Permeation properties of different gas pair systems (O2-N2, H2-CO2, CO2-CH4, C3H6-C3H8, CH4-n-C4H10) were studied using the time lag technique.
ABSTRACT
Three different crystal forms were obtained from the crystallisation of a flexible imidazole based ligand and CdBr(2) under different conditions. Structural analysis reveals that the correlation between the three metallocyclic compounds can be described in terms of isostructurality, solvatomorphism and supramolecular isomerism.
