Temperature Induced Structural Transformations and Gas Adsorption in the Zeolitic Imidazolate Framework ZIF-8: A Raman Study

Abstract

Here we have used Raman spectroscopy to investigate molecular level changes in the zeolitic imidazolate framework ZIF-8 (a prototypical zeolite-like porous metal organic framework) as a function of temperature. Temperature dependent Raman spectra suggest that at low temperature the softening of the C-H stretching frequencies is due to the decrease in steric hindrance between the methyl groups of methyl imidazole. The larger separation between the methyl groups opens the window for increased nitrogen and methane uptake at temperatures below 153 K. The appearance of Raman bands at 2323 cm(-1) and 2904 cm(-1) at or below 153 K in ZIF-8 are characteristic signatures of the adsorbed nitrogen and methane gases respectively. Nanoscale ZIF-8 uptakes more molecules than bulk ZIF-8, and as a result we could provide evidence for encaged CO2 at 203 K yielding its Raman mode at 1379 cm(-1).

Ultrarobust Biochips with Metal–Organic Framework Coating for Point-of-Care Diagnosis

“…58 After ZIF-8 coating, characteristic peaks of 2-methylimidazole were observed at 1142, 1178, 1459 and 1500 cm −1 corresponding to C–N stretching, C–N stretching plus N–H wagging, C–H wagging and C–N stretching plus N-H wagging, respectively (Figure 3F). 59–60 XRD measurements also confirmed the formation of ZIF-8 crystals on the biochip surface (Figure 3G). The related peak positions in XRD patterns were consistent with the typical structure of pure ZIF-8.…”

Zeolitic imidazolate frameworks‐8 modified graphene as a green flame retardant for reducing the fire risk of epoxy resin

“…Figure shows the Raman spectra of ZIF8, RGO, and ZIF‐8/RGO hybrid material. In the Raman spectra of ZIF‐8, the major peaks located at 178, 687, 1148, 1188, and 1461 cm −1 belong to Zn―N, imidazole rings, C 5 ―N, C―N, and rock vibration peak of C―H, respectively . For RGO and ZIF‐8/RGO, 2 peaks at 1390 and 1350 cm −1 belong to the D and G peak, respectively.…”

H2S interaction with HKUST-1 and ZIF-8 MOFs: A multitechnique study

“…The sample in air (grey curve) shows the typical Raman fingerprint of ZIF-8. Very strong bands were observed at 173 cm À1 , 686 cm À1 , 1149 cm À1 , and 1463 cm À1 corresponding to ZneN stretching, imidazole ring puckering, C5eN stretching and methyl bending, respectively [31]. Unfortunately, in this case, it is not possible to study the vibrational perturbations upon H 2 S dosages, as already the activated sample gives very strong fluorescence covering all the possible Raman signals in the considered range.…”