TY - JOUR

T1 - Water Modulated Framework Flexibility in NH2-MIL-125: Highlights from 13C Nuclear Magnetic Resonance

AU - Pizzanelli, Silvia

AU - Freni, Angelo

AU - Gordeeva, Larisa G.

AU - Forte, Claudia

N1 - Funding Information: L. G. Gordeeva thanks the Russian Foundation for Basic Researches (grant no. 18-29-04033) for partial financial support of this work. The authors acknowledge Regione Toscana POR FESR 2014–2020 for the project FELIX (Fotonica ed Elettronica Integrate per l’Industria), grant number 6455. Publisher Copyright: © 2021 Taylor & Francis Group, LLC.

PY - 2022

Y1 - 2022

N2 - The influence of adsorbed water on the dynamics of the organic linker 1,4-benzenedicarboxylate (BDC) in the metal organic framework NH2-MIL-125 was examined by applying 13C Nuclear Magnetic Resonance (NMR) spectroscopy on samples loaded with different amounts of water. In particular, the analysis of (i) cross-polarization (CP) 13C Magic Angle Spinning (MAS) NMR spectra in terms of chemical shift and line width of the carbon signals, (ii) variable contact time 13C CP-MAS experiments, and (iii) longitudinal 13C relaxation times indicated that, upon hydration, a dynamic process occurring on the microseconds timescale accelerates. This process could be identified with the rotation of the BDC benzene ring about its C2 axis, with water competing with the carboxylic oxygen for hydrogen bonding with the aminic group. Other motions occurring at frequencies on the order of the 13C Larmor frequency, i.e. 75 MHz, which contribute to the flexibility of the three-dimensional network, were detected, and identified with the twisting, libration and translation of the BDC linker.

AB - The influence of adsorbed water on the dynamics of the organic linker 1,4-benzenedicarboxylate (BDC) in the metal organic framework NH2-MIL-125 was examined by applying 13C Nuclear Magnetic Resonance (NMR) spectroscopy on samples loaded with different amounts of water. In particular, the analysis of (i) cross-polarization (CP) 13C Magic Angle Spinning (MAS) NMR spectra in terms of chemical shift and line width of the carbon signals, (ii) variable contact time 13C CP-MAS experiments, and (iii) longitudinal 13C relaxation times indicated that, upon hydration, a dynamic process occurring on the microseconds timescale accelerates. This process could be identified with the rotation of the BDC benzene ring about its C2 axis, with water competing with the carboxylic oxygen for hydrogen bonding with the aminic group. Other motions occurring at frequencies on the order of the 13C Larmor frequency, i.e. 75 MHz, which contribute to the flexibility of the three-dimensional network, were detected, and identified with the twisting, libration and translation of the BDC linker.

UR - http://www.scopus.com/inward/record.url?scp=85119293319&partnerID=8YFLogxK

U2 - 10.1080/01457632.2021.2000753

DO - 10.1080/01457632.2021.2000753

M3 - Article

AN - SCOPUS:85119293319

VL - 43

SP - 1664

EP - 1674

JO - Heat Transfer Engineering

JF - Heat Transfer Engineering

SN - 0145-7632

IS - 19

ER -