The Interplay Between Conformation and Absolute Configuration in Chiral Electron Dynamics of Small Diols. Issue 37 (22nd July 2016)

• Record Type: Journal Article
• Authors: Daly, Steven; Tia, Maurice; Garcia, Gustavo A.; Nahon, Laurent; Powis, Ivan
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 37(2016)
• Page Start: 11054
• Page End: 11058
• Publication Date: 2016-07-22
• Subjects: absolute configuration -- chirality -- circular dichroism -- 1, 3-propanediol; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201603771
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A competition between chiral characteristics alternatively attributable to either conformation or to absolute configuration is identified. Circular dichroism associated with photoexcitation of the outer orbital of configurational enantiomers of 1, 3‐ and 2, 3‐butanediols has been examined with a focus on the large changes in electron chiral asymmetry produced by different molecular conformations. Experimental gas‐phase measurements offer support for the theoretical modeling of this chiroptical effect. A surprising prediction is that a conformationally produced pseudo‐enantiomerism in 1, 3‐butanediol generates a chiral response in the frontier electron dynamics that outweighs the influence of the permanent configurational handedness established at the asymmetrically substituted carbon. Induced conformation, and specifically induced conformational chirality, may thus be a dominating factor in chiral molecular recognition in such systems. Abstract : Methyl substitution at a terminal carbon of 1, 3‐propanediol creates a new stereogenic center, and hence permanent R and S configurational enantiomers of 1, 3‐butanediol. However, the HOMO electron dynamics are predicted to continue displaying marked conformational pseudo‐enantiomerism analogous to the transient conformational chirality in 1, 3‐propanediol.