Optical rotation of noncovalent aggregates.
Dilute solutions of (R)-(-)-pantolactone in CCl4 were studied by polarimetry in conjunction with theoretical calculations of [alpha]D. Our data demonstrate that the self-association of a chiral solute results in a change in [alpha]D that can be accounted for by the presence of hydrogen-bonded dimeric species. The theoretical analysis predicts a concentration-dependent specific rotation in good agreement with experiment. Further exploration of monomer and dimer [alpha]D differences, through atomic map analysis, reveals large contributions to [alpha]D from the hydrogen-bonded hydroxyl groups in the tightly-coupled dimer. This study extends the computation of chiroptical properties to the accurate concentration-dependent prediction of [alpha]D for noncovalently interacting self-associating species.
Goldsmith
Michael-Rock
MR
Departments of Chemistry and Biochemistry, Duke University, Durham, North Carolina 27708, USA.
Jayasuriya
Nilu
N
Beratan
David N
DN
Wipf
Peter
P
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism; D013816:Thermodynamics
C005412:pantolactone; D015107:4-Butyrolactone