| 1. |
- Fischer, J., et al.
(författare)
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Looking at hydrogen motions in confinement The uniqueness of Quasi-Elastic Neutron Scattering
- 2014
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Ingår i: The European Physical Journal. Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 223:9, s. 1831-1847
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Forskningsöversikt (refereegranskat)abstract
- Why in a barren and hot desert, clays can contain a significant fraction of water? Why does concrete crack? How can we demonstrate that complexation of a drug does not alter its conformation in a way that affects its functionality? In this paper we present results on various studies using Quasi-Elastic Neutron Scattering aimed at clarifying these questions. To allow for a better understanding of neutron scattering, a brief introduction to the basics of its theory is presented. Following the theoretical part, experimental results dealing with the effects of confinement on the water dynamics caused by the interfaces in clays and the nano- and micro-pores of concrete are reviewed in detail. At the end, recent Quasi-Elastic Neutron Scattering investigations on the complexation of the local anesthetics Bupivacaine (BVC.HCl, C18H28N20.HCl.H2O) and Ropivacaine (RVC.HCl, C17H26N20.HCl.H2O) into the cyclic beta-cyclodextrin oligosaccharide are presented. To conclude, the perspectives that the European Spallation Source brings to this subject are discussed.
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| 2. |
- Tsapatsaris, Nikolaos, et al.
(författare)
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Polymorphism of Paracetamol: A New Understanding of Molecular Flexibility through Local Methyl Dynamics.
- 2014
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8392 .- 1543-8384. ; 11:3, s. 1032-1041
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the interplay of molecular flexibility and hydrogen bonding manifested in the monoclinic (form I) and orthorhombic (form II) polymorphs of paracetamol. By means of incoherent inelastic neutron scattering and density functional theory calculations, the relaxation processes related to the methyl side-group reorientation were analyzed in detail. Our computational study demonstrates the importance of considering quantum effects to explain how methyl reorientations and subtle conformational changes of the molecule are intertwined. Indeed, by analyzing the quasi elastic signal of the neutron data, we were able to show a unique and complex motional flexibility in form II, reflected by a coupling between the methyl and the phenyl reorientation. This is associated with a higher energy barrier of the methyl rotation and a lower Gibbs free energy when compared to form I. We put forward the idea that correlating solubility and molecular flexibility, through the relation between pKa and methyl rotation activation energy, might bring new insights to understanding and predicting drug bioavailability.
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