Date of Award
In this study, chiral ionic liquid (CIL) solvents were prepared and tested for their chiral discrimination ability by probing with luminescence quenching. The CIL's were also tested for their impurities, viscosity and density. These experiments will help to determine the ability of CIL's to act as solvents in asymmetric catalysis. The chiral ionic liquids in this study were composed of amino acid methyl ester cations and bis(trifluoromethane) sulfonimide or bistri flimide anions (i.e. I-alanine methyl ester bistriflimid e, d-alanine methyl ester bistr iflim ide and I-leuci ne methyl ester bistriflimde). Circularly polarized luminescence (CPL) and its quenching in the chiral ionic liq uid solvent was probed using a racemic mi xture of Eu(dpa)/ (where dpa = 2,6-pyridine dicarboxylate) and (+)-cobalt complexes as quencher molecules. CPL measurements of the europium complex dissolved in each of the three CIL's resulted in dissymmetry factors not equal to zero, illustrating that the CIL solvent was structurally interacting with th e europium complex and affecting its racemic equilibrium. D- AlaC 1Tf2N had an opposite and equall y dissymmetry factor than L- AlaC1Tf2N emphasizing the abi lity of the CIL to di ffe rentiate between the right and left hands of a chiral molecule. When both the racemic europium and (+)-cobalt complexes were dissolved in CIL, their wellcharacterized interaction in water, an achiral solvent, was diffe rent than their interaction in the CIL's. Both L-LeuC1Tf2N and L-AlaC 1Tf2N lessened the cobalt 's preference with one hand in an achiral solvent. L- LeuCI Tf2N actuall y changed the sign of the dissymmetry fac tor of the stereochemical interacti on between the europium and cobalt complexes in water. However, L-AlaCI Tf2N had a smaller affect, only making the dissymmetry factor less positive in compari son to the EuI(+)Co complex interaction in 8 water. These data show that the CIL is working as an effective chrial selector in a bimolecular interaction.
Heckman, Laurel Millikan, "Chiral Recognition Study of a Bimolecular Process in Amino Acid Chiral Ionic Liquids" (2011). Undergraduate Honors Thesis Collection. 113.