Power of Infrared and Raman Spectroscopies to Characterize Metal-Organic Frameworks and Investigate Their Interaction with Guest Molecules

Abstract

The variety of functionalities and porous structures inherent to metal-organic frameworks (MOFs) together with the facile tunability of their properties makes these materials suitable for a wide range of existing and emerging applications. Many of these applications are based on processes involving interaction of MOFs with guest molecules. To optimize a certain process or successfully design a new one, a thorough knowledge is required about the physicochemical characteristics of materials and the mechanisms of their interaction with guest molecules. To obtain such important information, various complementary analytical techniques are applied, among which vibrational spectroscopy (IR and Raman) plays an important role and is indispensable in many cases. In this review, we critically examine the reported applications of IR and Raman spectroscopies as powerful tools for initial characterization of MOF materials and for studying processes of their interaction with various gases. Both the advantages and the limitations of the technique are considered, and the cases where IR or Raman spectroscopy is preferable are highlighted. Peculiarities of MOFs interaction with specific gases and some inconsistent band assignments are also emphasized. Summarizing the broad analytical possibilities of the IR and Raman spectroscopies, we conclude that it can be applied in combinations with other techniques to explicitly establish the structure, properties, and reactivity of MOFs.

Pulsed Discharge Plasma in High-Pressure Environment for Water Pollutant Degradation and Nanoparticle Synthesis

“…It seems that the absorption peaks at 1340, 1582, and 2670 cm −1 corresponded to the D, G, and 2D band modes, respectively, which were clearly observed in the Raman spectra of solution product, where the D band exhibits disordered carbon mode and the G band exhibits ordered carbon mode [105,106]. Obviously, the absorption peak at around 2920 cm −1 , which was associated with the hydroxyl group, was also found in this Raman spectrum [107][108][109]. Panickar et al explained that the G mode is attributed to the stretching motion of the sp 2 -hybridized carbon atoms' At room temperature (25 • C), the argon solubility is around 0.252 × 10 −4 at a pressure of 0.1 MPa, while it could approach 9.28 × 10 −4 at a pressure of 4 MPa [99,100].…”

Infrared crystallography for framework and linker orientation in metal–organic framework films

“…2 The bands at 1570 cm À1 and 1616 cm À1 stem from the asymmetric carboxylate vibration, and the bands at 1390 cm À1 and 1423 cm À1 are assigned to the symmetric carboxylate vibration, which is consistent with previous reports. 39,41 The bands at 1465 and 1370 cm À1 in the 3D MOF stem from C-H vibrations of DABCO with a transition dipole (1,4-NDC) 2 DABCO films obtained from random and aligned Cu(OH) 2 nanobelts and corresponding SEM images, and polarized IR transmission spectra. n asymm (COO À ) bands are highlighted in orange, while the bands corresponding to the n symm (COO À ) band are highlighted in yellow.…”

Factors Affecting Hydrogen Adsorption in Metal–Organic Frameworks: A Short Review

“…To obtain such important information, vibrational spectroscopy plays a crucial role and is often notable in many cases. At present, IR and Raman spectroscopies are considered to be powerful tools for initial characterization of MOFs and their composites, including in situ measurements under hydrogen adsorption, in addition to their combinations with other techniques to study crystal structure and morphology, and physical and chemical properties of MOFs [ 193 ].…”