scholarly journals Metal–Organic Frameworks: On the Role of Enthalpic and Entropic Contributions to the Conformational Free Energy Landscape of MIL‐101(Cr) Secondary Building Units (Adv. Theory Simul. 12/2020)

2020 ◽  
Vol 3 (12) ◽  
pp. 2070027
Author(s):  
Loukas Kollias ◽  
David C. Cantu ◽  
Vassiliki‐Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio
2020 ◽  
Vol 3 (12) ◽  
pp. 2000092
Author(s):  
Loukas Kollias ◽  
David C. Cantu ◽  
Vassiliki‐Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

2020 ◽  
Author(s):  
Loukas Kollias ◽  
David Cantu ◽  
Vassiliki-Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

The thermo-structural behavior of metal-organic framework (MOF) precursors is responsible for regulating the introduction of defects in MOF structures during synthesis. In this paper, factors affecting the flexibility of MIL-101(Cr) half-secondary building units (half-SBUs) are evaluated in solution using enhanced sampling methods. In particular, entropic and enthalpic contributions to the conformational free energy landscape of isolated MIL-101(Cr) half-SBUs are calculated in water, in the presence and absence of ionic species (Na<sup>+</sup> and F<sup>-</sup>), and in N, N-dimethylformamide (DMF). This analysis leads to the observation that the interplay between enthalpy and entropy determines the most probable conformational state for half-SBUs. Furthermore, the role of enthalpy and entropy in the conformational rearrangement of an SBU is investigated in water, noting that entropic contributions are essential to stabilize configurations that depart from those coherent with the MIL-101(Cr) crystal structure. This analysis highlights the importance of explicitly considering entropic effects on the configurational ensembles of MOF building units and highlights the significant impact they have on the relative stability of crystal-like and non-crystal-like conformers.


2020 ◽  
Author(s):  
Loukas Kollias ◽  
David Cantu ◽  
Vassiliki-Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

The thermo-structural behavior of metal-organic framework (MOF) precursors is responsible for regulating the introduction of defects in MOF structures during synthesis. In this paper, factors affecting the flexibility of MIL-101(Cr) half-secondary building units (half-SBUs) are evaluated in solution using enhanced sampling methods. In particular, entropic and enthalpic contributions to the conformational free energy landscape of isolated MIL-101(Cr) half-SBUs are calculated in water, in the presence and absence of ionic species (Na<sup>+</sup> and F<sup>-</sup>), and in N, N-dimethylformamide (DMF). This analysis leads to the observation that the interplay between enthalpy and entropy determines the most probable conformational state for half-SBUs. Furthermore, the role of enthalpy and entropy in the conformational rearrangement of an SBU is investigated in water, noting that entropic contributions are essential to stabilize configurations that depart from those coherent with the MIL-101(Cr) crystal structure. This analysis highlights the importance of explicitly considering entropic effects on the configurational ensembles of MOF building units and highlights the significant impact they have on the relative stability of crystal-like and non-crystal-like conformers.


2020 ◽  
Author(s):  
Loukas Kollias ◽  
David Cantu ◽  
Vassiliki-Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

The thermo-structural behavior of metal-organic framework (MOF) precursors is responsible for regulating the introduction of defects in MOF structures during synthesis. In this paper, factors affecting the flexibility of MIL-101(Cr) half-secondary building units (half-SBUs) are evaluated in solution using enhanced sampling methods. In particular, entropic and enthalpic contributions to the conformational free energy landscape of isolated MIL-101(Cr) half-SBUs are calculated in water, in the presence and absence of ionic species (Na<sup>+</sup> and F<sup>-</sup>), and in N, N-dimethylformamide (DMF). This analysis leads to the observation that the interplay between enthalpy and entropy determines the most probable conformational state for half-SBUs. Furthermore, the role of enthalpy and entropy in the conformational rearrangement of an SBU is investigated in water, noting that entropic contributions are essential to stabilize configurations that depart from those coherent with the MIL-101(Cr) crystal structure. This analysis highlights the importance of explicitly considering entropic effects on the configurational ensembles of MOF building units and highlights the significant impact they have on the relative stability of crystal-like and non-crystal-like conformers.


2019 ◽  
Author(s):  
Loukas Kollias ◽  
David Cantu ◽  
Vassiliki-Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

The thermostructural behavior of metal-organic framework (MOF) precursors is responsible for regulating the introduction of MOF structure defects during synthesis. In this paper, we evaluate factors affecting the flexibility of MIL-101(Cr) half – secondary building units (half-SBUs) in solution using enhanced sampling methods. In particular, we calculate entropic and enthalpic contributions to the conformational free energy landscape of isolated MIL-101(Cr) half-SBUs, in water, in the presence and absence of ionic species (Na<sup>+</sup> and F<sup>-</sup>), and in N, N-dimethylformamide (DMF). We find that the interplay between enthalpy and entropy determines the most probable conformational state for half-SBUs. Furthermore, we investigate the role of enthalpy and entropy in the conformational rearrangement of an SBU in water, noting that entropic contributions are essential to stabilize configurations that depart from those coherent with the MIL-101(Cr) crystal structure. Our analysis highlights the importance of explicitly considering entropic effects on the configurational ensembles of MOF building units, as such effects can significantly impact the relative stability of structurally different conformers, which ultimately can be responsible for the formation of defects during materials synthesis.


2019 ◽  
Author(s):  
Loukas Kollias ◽  
David Cantu ◽  
Vassiliki-Alexandra Glezakou ◽  
Roger Rousseau ◽  
Matteo Salvalaglio

The thermostructural behavior of metal-organic framework (MOF) precursors is responsible for regulating the introduction of MOF structure defects during synthesis. In this paper, we evaluate factors affecting the flexibility of MIL-101(Cr) half – secondary building units (half-SBUs) in solution using enhanced sampling methods. In particular, we calculate entropic and enthalpic contributions to the conformational free energy landscape of isolated MIL-101(Cr) half-SBUs, in water, in the presence and absence of ionic species (Na<sup>+</sup> and F<sup>-</sup>), and in N, N-dimethylformamide (DMF). We find that the interplay between enthalpy and entropy determines the most probable conformational state for half-SBUs. Furthermore, we investigate the role of enthalpy and entropy in the conformational rearrangement of an SBU in water, noting that entropic contributions are essential to stabilize configurations that depart from those coherent with the MIL-101(Cr) crystal structure. Our analysis highlights the importance of explicitly considering entropic effects on the configurational ensembles of MOF building units, as such effects can significantly impact the relative stability of structurally different conformers, which ultimately can be responsible for the formation of defects during materials synthesis.


Author(s):  
Nayara Dantas Coutinho ◽  
Hugo Gontijo Machado ◽  
Valter Henrique Carvalho-Silva ◽  
Wender A. Silva

Recent studies have assigned hydroxide elimination and C=C bond formation step in base-promoted aldol condensation the role of having a strong influence in the overall rate reaction, in contrast to...


2010 ◽  
Vol 395 (1) ◽  
pp. 134-154 ◽  
Author(s):  
Xianglan He ◽  
Jason T. Giurleo ◽  
David S. Talaga

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