Monitoring adsorption-induced switching by 129Xe NMR spectroscopy in a new metal–organic framework Ni2(2,6-ndc)2(dabco)

The synthesis and structure of a new flexible metal-organic framework Ni(2)(2,6-ndc)(2)(dabco) (DUT-8(Ni), DUT = Dresden University of Technology, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane) as well as its characterization by gas adsorption and (129)Xe NMR spectroscopy is described. The compound shows reversible structural transformation without loss of crystallinity upon solvent removal and physisorption of several gases. Xenon adsorption studies combined with (129)Xe NMR spectroscopy turn out to be favorable methods for the detection and characterization of the so-called "gate-pressure" effect in this novel MOF material. The linewidth and chemical shift of the (129)Xe NMR signal are shown to be very sensitive parameters for the detection of this structural transition from a narrow pore system with low porosity to a wide pore state. The transition and threshold temperature is clearly detected.