A pillar[5]arene-calix[4]pyrrole enantioselective receptor for mandelate anion recognition

Lv, Yongjun; Xiao, Chao; Yang, Cheng

doi:10.1039/c8nj04802a

Cited by 20 publications

(11 citation statements)

References 24 publications

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“…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. We have demonstrated that the chirality of pillar[n]arene derivatives could be manipulated by external stimuli, including temperature, redox, light, and pressure ( Yao et al, 2017 ; Xiao et al, 2020 ; Yao et al, 2021a ; Yao et al, 2021b ).…”

Section: Introductionmentioning

confidence: 99%

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

Liu

Yao

et al. 2021

Front. Chem.

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Several new chiral pillar[4]arene[1]quinone derivatives were synthesized by reacting pillar[4]arene[1]quinone (EtP4Q1), containing four 1,4-diethoxybenzene units and one benzoquinone unit, with various chiral amines via Michael addition. Due to the direct introduction of chiral substituents on the rim of pillar[n]arene and the close location of the chiral center to the rim of EtP4Q1, the newly prepared compounds showed unique chiroptical properties without complicated chiral resolution processes, and unprecedented high anisotropy factor of up to −0.018 at the charge transfer absorption band was observed. Intriguingly, the benzene sidearm attached pillar[4]arene[1]quinone derivative 1a showed solvent- and complexation-driven chirality inversion. This work provides a promising potential for absolute asymmetric synthesis of pillararene-based derivatives.

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Section: Introductionmentioning

confidence: 99%

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

Liu

Yao

et al. 2021

Front. Chem.

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“…As a highly investigated anion receptor system, the calix[4]pyrrole scaffold was modified to provide enantioselectivity. Aromatic extension to produce pillar[5]arene‐calix[4]pyrrol receptors were found to differentiate between the stereoisomers of mandelate with a selectivity up 2.47 in DMSO [12a] and aliphatically extended calix[4]arene receptors with a selectivity up to 3.5 in DMSO [12d] . As a chiral director, substantial research efforts have been devoted towards the incorporating the bisbinaphthyl moiety into anion receptors.…”

Section: Resultsmentioning

confidence: 99%

“…Upon utilizing these concepts, the enantioselective binding of mandelate has been previously reported. [12] The majority of chiral receptors display limited anion affinity and enantioselectivity, thus, opportunities remain to develop novel chiral receptor motifs.…”

Section: Introductionmentioning

confidence: 99%

Preorganized Homochiral Pyrrole‐Based Receptors that Display Enantioselective Anion Binding

Karges

Cohen

2022

Eur J Org Chem

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Herein, a new scaffold for anion recognition based on a tripodal tris(pyrrolamide) motif is presented. The receptors were able to bind to a variety of anions with high affinity. Using density functional theory methods, the three-dimensional geometry of the receptor-anion complex was calculated. These calculations show that the receptors bind anions via a preorganized cavity of amide and pyrrole hydrogen bond donor groups. Based on these findings, homochiral tris(pyrrolamide) receptors were prepared, which produced 1.6-fold greater affinity for (S)-(+)-mandelate over (R)-(À )-mandelate, demonstrating the ability to differentiate between these enantiomeric anions. The interaction of (S)-(+)-mandelate and (R)-(À )-mandelate within the homochiral receptor was examined by solution NMR spectroscopy and theoretical calculations. These findings indicate that the preorganized positioning of the pyrrole groups and subsequent sterics allows to differentiate between the stereoisomeric anions.

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“…A great number of macrocyclic compounds have been developed for the purpose of studying their optical properties [10][11][12]. Recently, the chirality of a novel emerging host molecule, pillar[n]arenes, has attracted increasing attention [13][14][15][16]. Pillar[n]arenes are macrocyclic compounds that are composed of several hydroquinone ether units and are featured by the well-defined cavity, unique host-guest complexation properties, and readily chemical functionalization.…”

Section: Introductionmentioning

confidence: 99%

Resolution and Racemization of a Planar-Chiral A1/A2-Disubstituted Pillar[5]arene

Xiao

Liang

et al. 2019

Symmetry

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Butoxycarbonyl (Boc)-protected pillar[4]arene[1]-diaminobenzene (BP) was synthesized by introducing the Boc protection onto the A1/A2 positions of BP. The oxygen-through-annulus rotation was partially inhibited because of the presence of the middle-sized Boc substituents. We succeeded in isolating the enantiopure R P (R P , R P , R P , R P , and R P )-and S P (S P , S P , S P , S P , and S P )-BP, and studied their circular dichroism (CD) spectral properties. As the Boc substituent is not large enough to completely prevent the flip of the benzene units, enantiopure BP-f1 underwent racemization in solution. It is found that the racemization kinetics is a function of the solvent and temperature employed. The chirality of the BP-f1 could be maintained in n-hexane and CH 2 Cl 2 for a long period at room temperature, whereas increasing the temperature or using solvents that cannot enter into the cavity of BP-f1 accelerated the racemization of BP-f1. The racemization kinetics and the thermodynamic parameters of racemization were studied in several different organic solvents. or bithienyl groups, have been chemically grafted onto one or more hydroquinone ether units, and the oxygen-through-annulus rotation was restrained or completely stopped [21,22]. It occurred to us that if introducing a group of suitable size, the oxygen-through-annulus could still be allowed, but the rotation velocity is slowed down. This will then provide a powerful tool to study the effect of the external factors, such as the temperature and solvent, on the rotational kinetics of pillar[5]arene. Herein, we report on the successful isolation of butoxycarbonyl (Boc)-protected pillar[4]arene-[1]diaminobenzene (BP) planar chiral enantiomers. Two middle-sized Boc-protected substituents on the A1/A2 positions significantly decelerated the flip of pillar[5]arene, to allow for the racemization of BP with an observable velocity. The thermodynamics and kinetics of the racemization were investigated under different solvent and temperature conditions, which may serve as a guideline in the isolation and control of the enantiomeric conformations of pillar[n]arenes by manipulating the external factors. Materials and MethodsAll of the compounds and reagents were obtained from commercial suppliers and were used as received. Chiral analytical HPLC was performed with a Chiralpak IA column (0.46 × 25 cm) by a Shimadzu LC Prominence 20 HPLC instrument (Shimadzu, Tokyo, Japan) equipped with a UV-VIS detector (conditions: injection volume: 20 µL of rac-BP (0.2 mM); mobile phase: hexane/dichloromethane, 70/30 (v/v); flow rate: 1.0 mL/min at 20 • C; retention time (t R ): 5.3 min for BP-f1, 5.7 min for BP-f2). Preparative column chromatography was carried out with a Chiralpak IA column (1.0 × 25 cm) by a recycling preparative HPLC LC9210NEXT instrument (JAI, Tokyo, Japan) equipped with a UV-VIS detector (conditions: injection volume: 3 mL of rac-BP (2 mM); mobile phase: hexane/dichloromethane, 70/30 (v/v); flow rate: 4.0 mL/min at 20 • C; retention time (t R ): 11.4 min ...

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A pillar[5]arene-calix[4]pyrrole enantioselective receptor for mandelate anion recognition

Abstract: A novel pillar[5]arene-calix[4]pyrrole was synthesized as a chiral receptor for mandelate anions with a maximum enantioselectivity of 2.47.

Cited by 20 publications

References 24 publications

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

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

Preorganized Homochiral Pyrrole‐Based Receptors that Display Enantioselective Anion Binding

Resolution and Racemization of a Planar-Chiral A1/A2-Disubstituted Pillar[5]arene

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