pH-Controlled Chirality Inversion in Enantiodifferentiating Photocyclodimerization of 2-Antharacenecarboxylic Acid Mediated by γ-Cyclodextrin Derivatives

Abstract

Several γ-cyclodextrin (γ-CDx) derivatives were used as chiral hosts for the photocyclodimerization of 2-anthracenecarboxylic acid (AC). The effect of pH on photoreactivity and stereochemical outcome of photoproducts was investigated. Upon changing the solution pH, the stereochemical outcome of HH cyclodimer 3 was inverted from 25.2% to −64.4% and 41.2% to −76.2%, respectively, in the photocyclodimerization of AC mediated by bis-quinoline-modified γ-CDx 7 and its N-methylated derivative 8.

Single Isomer N-Heterocyclic Cyclodextrin Derivatives as Chiral Selectors in Capillary Electrophoresis

“…An opposite trend was observed for cCA and tPA, where the highest resolution values were obtained using 1 mM CD with outstanding enantioselectivity. PYR-β-CD was studied previously by Xiao et al [9], which correlates with our findings on the CD concentration-dependent enantioselectivity for MA, 2-PPA, chlorprop, dichlorprop, Dns-Ser and Dns-Val as well.…”

“…In this pH-dependent enantioselectivity study, the bottleneck of the experimental work was the solubility of the CDs, as it dropped strikingly, thus a maximum of 0.5 mM selector concentration could only be applied. Contrary to that, Xiao et al studied the pH-dependent enantioselectivity of PYR-β-CD previously in the pH 6.0-9.0 range at 5 mM selector concentration [9].…”

“…The structures of the final compounds were elucidated by using 1D-and 2D NMR techniques and confirmed by MALDI-TOF-MS (for detailed analytical data see Supplementary Materials Figure S1-S48). (9). The compounds 2-5 in (b) are the same as that in (a).…”

“…When the selector is a strong acid or base, the method development is simplified as the electrostatic analyte-selector interaction is ensured in the entire pH range, consequently, the selectivity can be determined as the charged resolving agent migration model (CHARM-model) describes [8]. On the contrary, the protonation state of weak electrolytes depends on the BGE pH, which offers the opportunity to fine-tune the analyteselector intermolecular interactions in order to enhance separation selectivity [3,9,10]. This approach is lying on the theory that by finding the optimal experimental conditions, the difference in the formation degree of diastereomeric complexes can be maximized [11].…”

Solvent-Driven Chirality Switching of a Pillar[4]arene[1]quinone Having a Chiral Amine-Substituted Quinone Subunit

“…On the other hand, supramolecular chiral photochemistry, which arises from the chiral spatial arrangement of noncovalently involved components in assemblies ( Crassous, 2009 ), has received booming development in recent years due to their close correlation with many natural and artificial systems and a wide range of potential applications ( Jung et al, 2001 ; Nakashima et al, 2001 ; Borovkov et al, 2003a ; Hembury et al, 2008 ; Yang and Inoue, 2014 ; Chen et al, 2015 ; Liu et al, 2015 ; Wang X. et al, 2020 ). Compared with molecular chirality, the supramolecular chirality is more attractive in terms of their regulatability by the external conditions such as temperature ( Yao et al, 2017 ; Fan et al, 2019 ), pH ( Kanagaraj et al, 2020 ; Liang et al, 2020 ; Hao et al, 2021 ), redox ( Xiao et al, 2020 ), light ( De Poli et al, 2016 ), chemical additives ( Lee et al, 2018 ), pressure ( Yao et al, 2021a ), and solvents ( Borovkov et al, 2003b ; Fan et al, 2019 ). Pillar[n]arenes ( Ogoshi et al, 2008 ; Xue et al, 2012 ; Pan et al, 2015 ; Fan et al, 2016 ; Jie et al, 2018 ; Lv et al, 2018 ; Li G. et al, 2019 ; Xiao et al, 2019 ; Ji et al, 2020a ; Lou and Yang, 2020 ; Mi et al, 2020 ; Liu et al, 2021 ; Peng et al, 2021 ), as a relatively new class of synthetic macrocyclic hosts with some unique properties ( Guo et al, (2018) ; Lai et al, (2019) ; Liu et al, (2019) ; Wang et al, (2021 ), have proved to be an ideal platform to construct unimolecular chirality based on different external stimuli-driven.…”