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Issue 14, 2011
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Structure–property relations in crystalline L-leucine obtained from calorimetry, X-rays, neutron and Raman scattering

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Abstract

We have studied the amino acidL-leucine (LEU) using inelastic neutron scattering, X-rays and neutron diffraction, calorimetry and Raman scattering as a function of temperature, focusing on the relationship between the local dynamics of the NH3, CH3, CH2 and CO2 moieties and the molecular structure of LEU. Calorimetric and diffraction data evidenced two novel phase transitions at about 150 K (T1) and 275 K (T2). The dynamical susceptibility function, obtained from the inelastic neutron scattering results, shows a re-distribution of the intensity of the vibrational bands that can be directly correlated with the phase transitions observed at T1 and T2, as well as with the already reported phase transition at T3 = 353 K. Through the analysis of the Raman modes, the new structural arrangement observed below T1 was related to conformational modifications of the CH and CH3 groups, while the behavior of the N–H stretching vibration, ν(NH3), gave insight into the intermolecular N–H…O interactions. The observation of changes in the translational symmetry in the crystalline lattice, as well as anharmonic dynamics, allows for localized motions in LEU.

Graphical abstract: Structure–property relations in crystalline l-leucine obtained from calorimetry, X-rays, neutron and Raman scattering

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Publication details

The article was received on 26 Oct 2010, accepted on 03 Feb 2011 and first published on 07 Mar 2011


Article type: Paper
DOI: 10.1039/C0CP02278K
Citation: Phys. Chem. Chem. Phys., 2011,13, 6576-6583
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    Structure–property relations in crystalline L-leucine obtained from calorimetry, X-rays, neutron and Raman scattering

    P. F. Façanha Filho, X. Jiao, P. T. C. Freire, J. A. Lima Jr., A. O. dos Santos, P. F. Henry, F. Yokaichiya, E. Kremner and H. N. Bordallo, Phys. Chem. Chem. Phys., 2011, 13, 6576
    DOI: 10.1039/C0CP02278K

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