Enantiodifferentiating Photocyclodimerization of 2‑Anthracenecarboxylic Acid via Competitive Binary/Ternary Hydrogen-Bonded Complexes with 4‑Benzamidoprolinol

Abstract

Circular dichroism (CD) spectral examinations at various host/guest ratios revealed that 2-anthracenecarboxylic acid (AC) forms not only 1:1 but also novel 2:1 hydrogen-bonded/π-stacked complexes with a chiral 4-benzamidoprolinol template (TKS159). The 2:1 complexation is a minor process but causes significant CD spectral changes as a consequence of the exciton coupling interaction of two AC chromophores and greatly accelerates the head-to-head photocyclodimerization to significantly affect the stereochemical outcomes