New Pillar-MOF with Nitrogen-Donor Sites for CO2 Adsorption

Abstract
A new pillar-MOF [Zn2(L)(DABCO)] was solvo-thermally synthesized by using a new linker (L = 4,4′-(1,4-phenylenebis(3,5-dimethyl-1H-pyrazole-4,1-diyl))dibenzoic acid),Zn(NO3)2·6H2O, and triethylenediamine (DABCO) as pillarlinker. It was characterized using single-crystal X-ray diffraction,powder X-ray diffraction (PXRD), thermogravimetric analysis(TGA), and scanning electron microscopy (SEM) and tested forCO2 adsorption. It exhibits dinuclear paddle−wheel nodes wherethe Zn(II) cations are coordinated by four equatorial L linkersgenerating two-dimensional sheets. DABCO acted as a pillarbinding the sheets to obtain a neutral three-dimensional frameworkthat shows one-dimensional square channels. The new pillar-layered MOF presents micro- and mesopores, and its crystallinity is preserved after activation at 160 °C × 16 h and adsorption ofCO2. Due to the presence of the pyrazole nitrogen atoms in the framework, which have an increased affinity toward CO2, this newmaterial exhibited a reasonable CO2 uptake capacity and a low isosteric enthalpy of adsorption (Hads)
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