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Polarimetry as a Tool for the Study of Solutions of Chiral Solutes
Author(s) -
Orlova Anna V.,
Andrade Renato R.,
da Silva Clarissa O.,
Zinin Alexander I.,
Koov Leonid O.
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300894
Subject(s) - chemistry , aqueous solution , levoglucosan , solvation , molecule , conformational isomerism , analytical chemistry (journal) , computational chemistry , chromatography , organic chemistry , aerosol , biomass burning
Optical rotation of aqueous solutions of D ‐levoglucosan was studied experimentally in the 0.03–4.0 mol L −1 concentration range and a nonlinear concentration dependence of specific optical rotation (SR) was revealed. Discontinuities observed in the concentration plot of SR (at 0.1, 0.3, 0.5, 1.0, and 2.0 mol L −1 ) are well correlated with those found by static and dynamic light scattering and identify concentration ranges in which different solution domains (supramers) may exist. The average SR experimental value for a D ‐levoglucosan aqueous solution ([ α ] D 28 −58.5±8.7 deg dm −1 cm −3 g −1 ) was found to be in good agreement with values obtained by theoretical calculation (TD‐DFT/GIAO) of SR for 15 different conformers revealed by conformational sampling at the PCM/B3LYP/6‐311++G(2d,2p)//B3LYP/6‐31+G(d,p) level, which were shown to be strongly affected by the solvation microenvironment (0, 1, 2, and 3 explicit solvent molecules considered) due to local geometrical changes induced in the solute molecule. This exceptionally high sensitivity of SR makes polarimetry a unique method capable of sensing changes in the structure of supramers detected in this study.