Low-Pressure Selectivity, Stepwise Gas Sorption Behaviors, and Luminescent Properties (Experimental Findings and Theoretical Correlation) of Three Zn(II)-Based Metal–Organic Frameworks

Abstract

In this report, three new luminescent metal–organic frameworks (LMOFs), [Zn(L1)2]·CH3CN (1), [Zn(L1)2] (2), and [Zn(L1)(L2)0.5]·NMP (3) (HL1 = 6-aminonicotinic acid; H2L2 = terephthalic acid; and NMP = N-methyl-2-pyrrolidone), have been solvothermally synthesized based on d10 metal ion Zn(II) and free organic ligands (HL1 and H2L2) in different solvent systems, all of which have been fully characterized. Single crystal data reveal that 1 and 2 are two 2D isomeride but with different space groups, which is caused by the different solvent systems during the synthesis procedure. The introduction of the bridging ligand H2L2 in the solvent system of 2 produces 3 with the 3D microporous framework. The gas sorption exploration of 3 shows an interesting stepwise gas sorption behavior and attractive low-pressure selectivity between CO2 and CH4, which may be used as a potential material to separate the CO2 from the natural gas. In addition, the luminescent properties of the free ligands and 1–3 have been investigat...