Supramolecular complexation and photochirogenesis with inherently chiral molecular clip: enantiodifferentiating photoisomerization of (Z,Z)-1,3-cyclooctadiene and polar photoaddition to 1,1-diphenylpropene

Abstract

Inherently chiral molecular clip (MC) binds (Z,Z)-1,3-cyclooctadiene () and 1,1-diphenylpropene () in 4:1:5 THF-MeOH-H2O solution (at 25 degrees C) with association constants of 8800 and 27000 M(-1), respectively. The thermodynamic parameters obtained from the van't Hoff analysis (DeltaH degrees=-96.4 kJ mol(-1), DeltaS degrees=-239 J mol(-1) K(-1)) reveal that the binding of by MC is strongly driven by the enthalpic gain from hydrophobic and pi-pi stacking interactions, which is however largely cancelled out by the entropic loss arising from the tight molecular association. Supramolecular photosensitization by MC facilitates the Z-E isomerization of to chiral (E,Z)-isomer in a good E/Z ratio of 0.19 and a low ee of 0.7%, but does not appear to work with probably due to the less-efficient electron transfer in the acceptor-donor-acceptor complex of with MC .