In the present work, we discuss the structural features of some amino-acid chiral ionic liquids (CILs), L-Proline alkyl esters nitrates and chlorides. These compounds have recently shown very good capabilities in chiral discrimination studies such as separations and asymmetric syntheses. Energy-Dispersive X-Ray patterns of L-Proline alkyl esters (ethyl, propyl, butyl, pentyl and hexyl) chlorides were obtained and confronted with theoretical curves calculated from molecular dynamics trajectories. In the structure factors of all the liquids examined, pre-peaks (FSDP) of intensity proportional to the alkyl chain length are present, but, more surprisingly, from butyl chain upwards, the principal scattering peak appears to be split into two contributions, resembling what happens in liquid water. The spatial arrangement of the ions giving origin to these patterns is discussed
Short and medium-range Order in L-Proline Esters Ionic Liquids: A X-Ray and MD Study
GONTRANI, LORENZO;
2013-01-01
Abstract
In the present work, we discuss the structural features of some amino-acid chiral ionic liquids (CILs), L-Proline alkyl esters nitrates and chlorides. These compounds have recently shown very good capabilities in chiral discrimination studies such as separations and asymmetric syntheses. Energy-Dispersive X-Ray patterns of L-Proline alkyl esters (ethyl, propyl, butyl, pentyl and hexyl) chlorides were obtained and confronted with theoretical curves calculated from molecular dynamics trajectories. In the structure factors of all the liquids examined, pre-peaks (FSDP) of intensity proportional to the alkyl chain length are present, but, more surprisingly, from butyl chain upwards, the principal scattering peak appears to be split into two contributions, resembling what happens in liquid water. The spatial arrangement of the ions giving origin to these patterns is discussed
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