(NMR) spectroscopy. All 1 H, C, N, Na and 31 P experiments were performed on a Bruker 400 MHz (9.4 T) Avance III HD NMR spectrometer equipped with a 4 mm triple-resonance HXY MAS probe in double resonance mode tuned to 1 H at υ0( 1 H) = 400.1 MHz and 31 P at υ0( 31 P) = 162.0 MHz or C at υ0( 13 C) = 100.6 MHz or N at υ0( 15 N) = 40.6 MHz or Na at υ0( 23 Na) = 105.8 MHz. Samples were packed in 4 mm ZrO2 rotors and spun under a MAS at υr = 10 kHz for 1 H, C, Na and P and at υr = 8 kHz for N. H pulses and SPINAL-64 heteronuclear decoupling during C/ 15 N / 31 P detection were carried out with radio frequency (rf) field amplitudes of 56 kHz and 67 kHz, respectively, for C experiments, 43.5 kHz and 47 kHz, respectively, for N experiments, and 52.6 kHz and 62 kHz, respectively for P experiments and 56 kHz and 67 kHz, respectively for C experiments. Na and 31 P pulses for the directly excited spectra were obtained using 90º pulse lengths of 5.8 and 5.5 µs using rf field amplitude of 43 and 45.4 kHz, respectively. The Hartmann-Hahn matched conditions for cross polarisation (CP) were achieved using a C rf amplitude of 42 kHz ramped from 70 to 100% to obtain maximum signal at a 1 H rf field amplitude of 56 kHz, a N rf field amplitude of 20 kHz ramped similarly to obtain maximum signal at a 1 H rf field amplitude of 32 kHz. The contact times for all CP-based experiments are indicated in the figure captions and range between 50 µs and 2 ms. Frequency switched Lee-Goldberg (FSLG) homonuclear decoupling at a rf amplitude of 62 kHz and a LG offset of 0 Hz was used during the 1 H evolution time in the two-dimensional (2D) 1 H-31 P heteronuclear correlation (HETCOR) spectra. Experimentally determined 1 H scaling factors λexp for FSLG were measured by comparing the 1 H spectra under MAS and the 1 H projection of the 2D CP HETCOR for all samples and were found to be λexp = 0.7; these were then used to recover the full 1 H chemical shifts in the 2D CP HETCOR from the scaled-down chemical shifts that resulted from decoupling. C/ 15 N / 31 P CP and quantitative 1 H MAS NMR spectra were obtained with recycle delays of 1.3 times the 1 H spin lattice relaxation times T1 (measured via a standard saturation recovery experiment and of typical values of 6 s), respectively, while the Na and 31 P MAS NMR spectra were obtained under quantitative relaxation assessed from variable recycle delays array experiments (typically 5 s and 30 s, respectively). All 67 Zn MAS NMR experiments were recorded on a Bruker 800 MHz (18.8 T) Avance Neo spectrometer equipped with a 3.2 mm HX probe tube to υ0( 67 Zn) = 50.09 MHz. The samples were packed in 3.2 mm ZrO2 rotors and collected under MAS at υr = 10 kHz. Spectra were obtained with a rotor-synchronised (3 rotor periods for crystalline ZIF-8/physical mixture/composite and 1 rotor period for amorphous ZIF-8) full echo pulse lengths of 5.5 µs and 11 µs, respectively, at a rf field amplitude of 15 kHz. A 2 ms double-frequency sweep from from ± 800 kHz to ± 200 kHz at a rf field amplitude of 3.5 kHz allowing inversion of population of the satel-lite transitions leading to an experimental gain in sensitivity of approximately 1.3 was used. Experiments were recorded using recycle delays of either 1 or 0.1 s for crystalline ZIF-8/physical mixture/composite and amorphous ZIF-8, respectively. 1 H, C, N, P and 67 Zn spectra were externally referenced to adamantane at 1.8 ppm, the tertiary carbon of adamantane at 29.45 ppm, gycine at 33.44 ppm, and 85% H3PO4 in H2O at 0 ppm, respectively. All data were processed with the Topspin software using standard procedures.