A close view of the organic linker in a MOF: structural insights from a combined 1H NMR relaxometry and computational investigation. Issue 27 (30th June 2020)

• Record Type: Journal Article
• Authors: Pizzanelli, Silvia; Monti, Susanna; Gordeeva, Larisa G.; Solovyeva, Marina V.; Freni, Angelo; Forte, Claudia
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 27(2020)
• Page Start: 15222
• Page End: 15230
• Publication Date: 2020-06-30
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp01863e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Fast Field Cycling NMR combined with ReaxFF MDs and the PAW/GIPAW approach is used to characterize the amine nitrogen EFG tensor and its dynamics. Abstract : The organic linker in a metal organic framework (MOF) affects its adsorption behavior and performance, and its structure and dynamics play a role in the modulation of the adsorption properties. In this work, the combination of 1 H nuclear magnetic resonance (NMR) longitudinal relaxometry and theoretical calculations allowed details of the structure and dynamics of the organic linker in the NH2 -MIL-125 MOF to be obtained. In particular, fast field cycling (FFC) NMR, applied here for the first time on MOFs, was used to disclose the dynamics of the amino group and its electronic environment through the analysis of the 14 N quadrupole relaxation peaks, observed in the frequency interval 0.5–5 MHz, at different temperatures from 25 to 110 °C. The line width of the peaks allowed a lower boundary on the rotational correlation time of the N–H bonds to be set, whereas relevant changes in the amplitudes were interpreted in terms of a change in the orientation of the 14 N averaged electric field gradient tensor. The experimental findings were complemented by quantum chemistry calculations and classical molecular dynamics simulations.