Combined solid-state NMR, FT-IR and computational studies on layered and porous materials

Abstract

Understanding the structure-property relationship of solids is of utmost relevance for efficient chemical processes and technological applications in industries. This contribution reviews the concept of coupling three well-known characterization techniques (solid-state NMR, FT-IR and computational methods) for the study of solid state materials which possess 2D and 3D architectures and discusses the way it will benefit the scientific communities. It highlights the most fundamental and applied aspects of the proactive combined approach strategies to gather information at a molecular level. The integrated approach involving multiple spectroscopic and computational methods allows achieving an in-depth understanding of the surface, interfacial and confined space processes that are beneficial for the establishment of structure-property relationships. The role of ssNMR/FT-IR spectroscopic properties of probe molecules in monitoring the strength and distribution of catalytic active sites and their accessibility at the porous/layered surface is discussed. Both experimental and theoretical aspects will be considered by reporting relevant examples. This review also identifies and discusses the progress, challenges and future prospects in the field of synthesis and applications of layered and porous solids.

Molecular‐level Understanding of the Rate‐determining Step in Esterification Reactions Catalyzed by H‐ZSM‐5 Zeolite. An Experimental and Theoretical Study

“…Micro and mesoporous catalytic materials are very complex solid‐state systems, and very often single or coupling experimental analyses as IR and NMR solid state spectroscopy show limitations due to their spatial and temporal resolution. However, the robust approach of the quantum chemistry allows a more detailed assignment of the spectrum, being capable of producing information of a single adsorbed molecule within pores and cavities that have a frequency of vibration within a large experimental wavelength associated only to interactions at the surface of the solid …”

“…Additionally, computational approaches can be applied to gain novel and valuable molecular insights into adsorption mechanisms . A recent review highlighted the combination of theoretical and experimental techniques applied to describe the reaction mechanisms, for example, FTIR spectra have been interpreted with the help of the DFT calculation in order to describe adequate chemical models of interacting systems …”

Computer modeling of apparently straight bond angles: The intriguing case of all-silica ferrierite

“…Adsorption of geochemical fluids, solar energy transfer, or catalytic cracking all occur within zeolite nanospaces (Tabacchi 2018). These processes require multi-technique approaches in order to be understood, exploited, and improved (Van Speybroeck et al 2015;Evans et al 2017;Paul et al 2018;Li and Pidko 2019). Computational techniques -such as geometric models (Sartbaeva et al 2008;Wells and Sartbaeva 2012;Fletcher et al 2015;Wells et al 2015), force field methods (Demontis et al 1991(Demontis et al , 2017Desbiens et al 2005;Cailliez et al 2008;Coudert et al 2009;Demontis and Suffritti 2009;Wang et al 2014) and quantum chemistry calculations (Campana et al 1997;Ugliengo et al 2005;Coudert et al 2006;Giustetto et al 2011;Dovesi et al 2018) -are effective tools to address these issues.…”

Hybrid catalysts based on N-heterocyclic carbene anchored on hierarchical zeolites

“…A combined study coupling FTIR and ssNMR spectroscopies has been performed to elucidate the interaction of the organic NHC moiety with the inorganic supports and to evidence the OH population before and aer the organic graing in order to understand the role of the hierarchical supports in stabilizing NHC molecules and the fraction of the OH involved in the NHC graing. 26 In order to establish if the Si-OH group in NHC/HP-HZSM-5 have been consumed upon NHC graing and if the bridging Si-OH-Al groups (Brønsted acid sites, BAS) typical of the HZSM-5 and SAPO-5 frameworks have been retained aer the graing procedure, FT-IR spectra of NHC/HP-HZSM-5, NHC/HP-SAPO-5 and their inorganic analogue HP-HZSM-5 and HP-SAPO-5 were recorded ( Fig. 3 and 4).…”