Room-temperature phosphorescent γ-cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes for specific sensing of tryptophan

Yu, Xingke; Liang, Wenting; Huang, Qinfei; Wu, Wanhua; Chruma, Jason J.; Yang, Cheng

doi:10.1039/c9cc00097f

Cited by 72 publications

(37 citation statements)

References 41 publications

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“…The plots of ln(θ 0 /θ t ) against time gave straight lines, supporting the first-order kinetic model [25]. Increasing the temperature usually increases the reaction kinetics, and we have demonstrated that the temperature is critical for affecting the molecular recognition and stereoselectivity of supramolecular photochirogenesis [26][27][28][29][30][31][32][33]. To understand the temperature effect on the racemization of BP-f1, the CD ex versus time was recorded at different temperatures.…”

Section: Bp-f1supporting

confidence: 66%

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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Section: Bp-f1supporting

confidence: 66%

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

Xiao

Liang

et al. 2019

Symmetry

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“…At 298 K, two broad signals were observed for the aromatic protons of the biphenyl units of the two [5]catenanes at about δ =7.5 ppm and 7.6 ppm. Because of the asymmetry of the β‐CD, four sets of coupled doublets are expected for the aromatic protons of the included biphenyl when the β‐CD is relatively static . If the β‐CD is able to exchange its position, in the slow exchange regime, multiple sets of signals are to be expected.…”

Section: Resultsmentioning

confidence: 99%

Radial Hetero[5]catenanes: Peripheral Isomer Sequences of the Interlocked Macrocycles

Yee

Au‐Yeung

2019

Angewandte Chemie

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A pair of radial [5]catenanes, with either an isomeric cyclic ‐AABB‐ or ‐ABAB‐ type sequence of the interlocked β‐cyclodextrin (β‐CD) and cucurbit[6]uril (CB[6]) units, has been efficiently synthesized. Because of a marked difference in the binding strength and interlocking sequence of the peripheral macrocycles, interesting sequence‐dependent properties, characteristic of mechanically bonded macrocycles, were realized. Variable‐temperature 1H NMR studies showed that the ‐ABAB‐ isomer has a more independent β‐CD dynamic, whereas the β‐CD motions in the ‐AABB‐ isomer are coupled. Dynamics of the pH‐insensitive β‐CD can also be further modulated upon base‐triggered mobilization of the CB[6]. These unique properties of the mechanical bond expressed in a sequence‐specific fashion and the transmission of the control on the macrocycle dynamics from one interlocked component to another, highlight the potential of similar complex hetero[n]catenanes in the design of advanced, multicomponent molecular machines.

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“…Room-temperature phosphorescence (RTP) emitted by purely organic molecules has been attracting increasing attention owing to its advantages over fluorescence, such as longer lifetime, larger Stokes shift, and the involvement of triplet states 1 – 6 . Such phosphorescent materials have therefore been widely used in organic light-emitting diodes 7 , 8 , data-security 9 , 10 , sensing 11 , 12 , and bioimaging 13 , 14 applications, among others. RTP is usually achieved by means of crystalline packing 15 , 16 or by embedding phosphors in a rigid matrix 9 , 17 , 18 .…”

Section: Introductionmentioning

confidence: 99%

“…Macrocyclic compounds (i.e., cyclodextrin, cucurbituril) have become a research hotspot for realizing purely organic phosphorescence in aqueous solution due to their special properties of internal hydrophobicity/external hydrophilicity and host-guest interactions 12,[26][27][28][29][30][31][32] . Up to now, although the phosphorescence in water has made great progress through the host-guest interactions, the purely organic phosphorescence with long lifetime and function in water is rarely reported and still faces great opportunities and challenges.…”

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confidence: 99%

Ultralong purely organic aqueous phosphorescence supramolecular polymer for targeted tumor cell imaging

et al. 2020

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Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature phosphorescent supramolecular polymer by combining cucurbit[n]uril (CB[7], CB[8]) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB[7] mediated pseudorotaxane polymer CB[7]/HA–BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB[8] results in biaxial pseudorotaxane polymer CB[8]/HA–BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB[8] and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.

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Room-temperature phosphorescent γ-cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes for specific sensing of tryptophan

Abstract: The room temperature phosphorescence of iodine-substituted-γ-CD-CB[6]-cowheeled[4] rotaxanes was quenched specifically by tryptophan among plasma amino acids.

Cited by 72 publications

References 41 publications

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

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

Radial Hetero[5]catenanes: Peripheral Isomer Sequences of the Interlocked Macrocycles

Ultralong purely organic aqueous phosphorescence supramolecular polymer for targeted tumor cell imaging

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