Wolter F. Jager

Dynamic Control and Amplification of Molecular Chirality by Circular Polarized Light

The enantiomers of a racemic photoresponsive material represent two distinct states that can be modulated with irradiation at a single wavelength by changing the handedness ofthe light. Dynamic control over molecular chirality was obtained by the interconversion of enantiomers of helically shaped molecules with either left or right circular polarized light (CPL). Photoresolution of the bistable compound as a dopant in a nematic liquid crystalline phase by CPL irradiation led to a chiral mesoscopic phase. The chiral information inherent to CPL is therefore transmitted to the bistable molecule, followed by amplification and macroscopic expression of the chirality.

Resolution of sterically overcrowded ethylenes ; a remarkable correlation between bond lengths and racemization barriers

The synthesis and resolution of 2-methyl-9H-thioxanthene-9-(9H-thioxanthen-9-ylidene) 1 and related structures 2-5, being the first examples of thermally stable optically active sterically overcrowded ethylenes, are reported. Substitution of the sulfur atom in the thioxanthene part of 1 with an X group (2, X = C(CH3)2; 3, NCH3; 4, O) results in a change in racemization barrier (1, 27.4 kcal.mol-1; 2, 25.1 kcal.mol-1; 3, 21.3 kcal.mol-1; 4, <20 kcal.mol-1) depending upon the aryl-X bond lenghts.

Sterically Overcrowded Alkenes : Synthesis, Resolution and Circular Dichroism Studies of Substituted Bithioxanthylidenes

Abstract Bithioxanthylidenes with small substituents at positions 2 and 2′ have been synthesized and resolved by chiral HPLC. The X-ray molecular structure of 9-(2′-methyl-9′H-thioxanthene-9′-ylidene)-9H-xanthene ( 17 ) confirms the folded form of these molecules. UV and CD studies of several bithioxanthylidenes are presented. The CD spectra of these molecules can be described qualitatively by subtracting the CD spectra of both differently sensed helices (M and P) present in the molecule, which can be distinguished by the substituents at positions 2 and 2′.

Chiroptical Molecular Switches 2; Resolution, Properties and Applications of Inherent Dissymmetric Alkenes.

Abstract The concept and the synthesis of the basic molecules for a chiroptical molecular switch are described. This molecular switch is based on photochemical interconversion of two bistable forms of chiral sterically overcrowded olefins. A large variety of these alkenes with different properties have been prepared by the use of a coupling reaction between a thioketone and a diazo compound.

Polystyrene based azo-dyes for non-linear optics; a new polymer-diazo coupling approach

A new direct functionalization of N-methylanilino-methylpolystyrene (α= 0.31) with p-nitrobenzenediazonium chloride yields an azastilbene modified polystyrene with excellent solubility properties.