Understanding guest and pressure‐induced porosity through structural transition in flexible interpenetrated MOF by Raman spectroscopy

Abstract

Interpenetrating metal organic frameworks are interesting functional materials exhibiting exceptional framework properties. Uptake or exclusion of guest molecules can induce sliding in the framework making it porous or non-porous. To understand this dynamic nature and how framework interaction changes during sliding, metal organic framework (MOF) 508 {Zn(BDC)( 4,4′-Bipy) 0.5 · DMF(H 2 O) 0.5 } was selected for study. We have investigated structural transformation in MOF-508 under variable conditions of temperature, pressure and gas loading using Raman spectroscopy and substantiated it with IR studies and density functional theory (DFT) calculations. Conformational changes in the organic linkers leading to the sliding of the framework result in changes in Raman spectra. These changes in the organic linkers are measured as a function of high pressure and low temperature, suggesting that the dynamism in MOF-508 framework is driven by ligand conformation change and inter-linker interactions. The presence of Raman signatures of adsorbed CO 2 and its librational mode at 149 cm À1 suggests cooperative adsorption of CO 2 in the MOF-508 framework, which is also confirmed from DFT calculations that give a binding energy of 34 kJ/mol.Additional supporting information may be found in the online version of this article at the publisher's web site.Understanding guest and pressure-induced porosity

Flexible ε-Fe2O3-Terephthalate Thin-Film Magnets through ALD/MLD

“…290, 860, and 1140 cm –1 can be assigned to the out-of-plane ring bending, the C–C stretching of the carboxylate group, and the superposition of ring breathing and in-plane bending of C–H. 44 , 45 The band due to in-plane bending of aromatic C–H appears at 1305 cm –1 . 45 The spectrum for our parent ( n = 0) sample shows all the features expected for ε-Fe 2 O 3 .…”

“… 44 , 45 The band due to in-plane bending of aromatic C–H appears at 1305 cm –1 . 45 The spectrum for our parent ( n = 0) sample shows all the features expected for ε-Fe 2 O 3 . 46 With an increase in the number of organic layers, the peaks due to ε-Fe 2 O 3 decrease in intensity, whereas those from the organic moiety increase with n .…”

Single particle Raman spectroscopy analysis of the metal–organic framework DUT-8(Ni) switching transition under hydrostatic pressure

“…22,32 Moreover, it can be applied for structure monitoring in situ, and can be easily performed on single crystals, opening the possibility to address specific questions and rule out the effects associated with the particle size distribution in a powder. 17,[32][33][34] Raman spectroscopy is also useful in case diffraction quality of single crystals suffers due to fracturing, 35 as amorphisation and bond breaking can be clearly detected. 17,[36][37][38] The closing behaviour of DUT-8(Ni)_op was investigated on a single crystal, containing N,N-dimethylformamide (DMF) in the pores and silicon oil as pressure transmittance medium.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part XI

“…Kumari et al presented a study aimed at understanding guest and pressure‐induced porosity through structural transition in flexible interpenetrated metal organic frameworks (MOF) that are interesting functional materials exhibiting exceptional framework properties. The authors investigated structural transformations in MOF‐508 under variable conditions of temperature, pressure, and gas loading using Raman spectroscopy and supported these results with IR studies and DFT calculations . Liu and co‐workers reported on number‐of‐layer, pressure, and temperature‐resolved bond‐phonon‐photon cooperative relaxation of layered black phosphorus.…”