Design and preparation of new luminescent metal–organic frameworks and different doped isomers: sensing pollution ions and enhancement of gas capture capacity†
Abstract
Two new metal–organic frameworks (MOFs), formulated as [Cd3(L)2(H2O)2]·2H2O (1) and [Zn2(L)(OH)(H2O)]·2DMA (2, DMA = N,N-dimethylacetamide), were first constructed via an unsymmetrical N-heterocyclic 5-((4-carboxypyridin-2-yl)oxy)isophthalic acid (H3L) ligand. Then, a proportion of the Zn(II) ions of 2 were substituted by fine-tuning the contents of Co(II) ions to obtain two new isomers, Co1-MOF 2 and Co2-MOF 2, the successful doping of which can be proved by PXRD, IR spectra, ICP, XPS, and SEM. The luminescent experiments suggested that complex 1 should be a good detector for detecting Fe3+ and Cr2O72− ions. More remarkably, the Co-rich MOF materials have increased gas capture for CO2 and CH4 compared to that of the Co-free isomer 2, and the absorption amount of CO2 and CH4 may rise with the increasing content of Co(II) ions in the system at higher pressure and lower temperature.