Chiral Molecular Cage with Tunable Stereoinversion Barriers

Gao, Wen-Bin; Li, Zhihao; Tong, Tianyi; Dong, Xue; Qu, Hang; Yang, Liulin; Sue, Andrew C.-H.; Tian, Zhong-Qun; Cao, Xiao-Yu

doi:10.1021/jacs.3c04761

Cited by 13 publications

(8 citation statements)

References 70 publications

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“…Chiral porous assemblies have received much attention − for their potential applications in enantioselective separation, − asymmetric catalysis, ,− enantioselective recognition, and circularly polarized luminescence. , However, research on the chirality of organic cages is still insufficient. Prior research on chiral covalent cages has primarily focused on chiral organocatalysts.…”

Section: Resultsmentioning

confidence: 99%

Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis

Wang,

Tang,

Anjali

et al. 2024

J. Am. Chem. Soc.

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Covalent organic cages are a prominent class of discrete porous architectures; however, their structural isomerism remains relatively unexplored. Here, we demonstrate the structural isomerism of chiral covalent organic cages that renders distinct enantioselective catalytic properties. Imine condensations of tetratopic 5,10-di(3,5-diformylphenyl)-5,10-dihydrophenazine and ditopic 1,2-cyclohexanediamine produce two chiral [4 + 8] organic cage isomers with totally different topologies and geometries that depend on the orientations of four tetraaldehyde units with respect to each other. One isomer (PN-1) has an unprecedented Johnsontype J 26 structure, whereas another (PN-2) adopts a tetragonal prismatic structure. After the reduction of the imine linkages, the cages are transformed into two amine bond-linked isomers PN-1R and PN-2R. After binding to Ni(II) ions, both can serve as efficient catalysts for asymmetric Michael additions, whereas PN-2R affords obviously higher enantioselectivity and reactivity than PN-1R presumably because of its large cavity and open windows that can concentrate reactants for the reactions. Density-functional theory (DFT) calculations further confirm that the enantioselective catalytic performance varies depending on the isomer.

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Section: Resultsmentioning

confidence: 99%

Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis

Wang,

Tang,

Anjali

et al. 2024

J. Am. Chem. Soc.

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“…Soc . 2023 , 145 , 17795–17804 . This work showcases that the racemization energy barrier of a stereochemically dynamic face-rotating polyhedron can be controlled through chemical modification.…”

Section: Key Referencesmentioning

confidence: 91%

“…The TDB units in FRP-10 are capable of undergoing stereomutation, transitioning between different enantiomeric conformations (Figure 11a). 4 Once enantiopure homodirectional FRP-10 was resolved using a prep-HPLC technique, detailed racemization kinetic studies of (4M)-10 were conducted by monitoring the attenuation of the CD spectra intensity and the appearance of (4P)-10 using HPLC analysis. On account of the flipping of the TDB facial unit, the racemization between (4P)-and (4M)-10 shows an activation energy barrier of 85.7 kJ mol −1 , which correspond to a rate constant k obs of 3.6 × 10 −2 min −1 .…”

Section: Stereomutation Of Frpmentioning

confidence: 99%

“…Although such flipping phenomenon is hindered in FRP- 6 (TPE) and FRP- 7 and - 8 (PPAP), a polyhedral FRP- 10 , constructed using tridurylborane (TDB) facial units, shows dynamic chirality. The TDB units in FRP- 10 are capable of undergoing stereomutation, transitioning between different enantiomeric conformations (Figure a) …”

Section: Exploring Static and Dynamic Stereochemistry In And Beyond Frpmentioning

confidence: 99%

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Molecular Face-Rotating Polyhedra: Chiral Cages Inspired by Mathematics

Dong,

Qu,

Sue

et al. 2024

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Molecular polyhedral cages, notable for their enclosed inner cavities, can possess varying degrees of symmetry, spanning from regular Platonic polyhedra to lower symmetry forms that may display chirality. Crafting chiral molecular cages typically involves using building blocks containing stereogenic elements or arranging achiral components in a manner that lacks mirror and inversion symmetries. Achieving precise control over their chirality poses both significance and challenges.In this Account, we present an overview of our research endeavors in the realm of chiral molecular polyhedral cages, drawing inspiration from Buckminster Fuller's "Face-Rotating Polyhedra (FRP)". Mathematically, FRP introduce a unique form of chirality distinguished by a rotating pattern around the center of each face, setting it apart from regular polyhedra. Molecular FRP can be constructed using two types of facial building blocks. The first includes rigid, planar molecules such as truxene and triazatruxene, which exhibit either clockwise or counterclockwise rotations in two dimensions. The second category involves propeller-like molecules, e.g., tetraphenylethylene, 1,2,3,4,5-penta(4-phenylaldehyde)pyrrole, and tridurylborane, displaying dynamic stereochemistry.The synthesis of FRP may potentially yield a diverse array of stereoisomers. Achieving high stereoselectivity becomes feasible through the selection of building blocks with specific substitution patterns and rigidity. Prominent noncovalent repulsive forces within the resulting cages often play a pivotal role in the dynamic covalent assembly process, ultimately leading to the formation of thermodynamically stable FRP products.The capacity to generate a multitude of stereoisomers, combined with the integration of chiral vertices, has facilitated investigations into phenomena such as chiral self-sorting and the "sergeant and soldiers" chiral amplification effect in FRP. Even the inclusion of one chiral vertex significantly impacts the stereochemical configuration of the entire cage. While many facial building blocks establish a stable rotational pattern in FRP, other units, such as tridurylborane, can dynamically transition between P and M configurations within the cage structures. The kinetic characteristics of such stereolabile FRP can be elucidated through physicochemical investigations.Our research extends beyond the FRP concept to encompass mathematical analysis of these structures. Graph theory, particularly the coloring problem, sheds light on the intricate facial patterns exhibited by various FRP stereoisomers and serves as an efficient tool to facilitate the discovery of novel FRP structures. This approach offers a fresh paradigm for designing and analyzing chiral molecular polyhedral cages, showcasing in our work the synergy between mathematics and molecular design.

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“…In contrast to the above, organic molecular cages, a class of intrinsically porous materials with accessible “windows”, have shown promise in the capture of micropollutants, including polar compounds . For instance, our group recently reported a porous adaptive metallacage that provides the removal of perfluorinated carboxylic acids (PFCA) from simulated contaminated water samples with high absorption efficiency .…”

Section: Introductionmentioning

confidence: 99%

Fluorinated Nonporous Adaptive Cages for the Efficient Removal of Perfluorooctanoic Acid from Aqueous Source Phases

He,

Zhou,

et al. 2024

J. Am. Chem. Soc.

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Per-and polyfluoroalkyl substances (PFAS) accumulate in water resources and pose serious environmental and health threats due to their nonbiodegradable nature and long environmental persistence times. Strategies for the efficient removal of PFAS from contaminated water are needed to address this concern. Here, we report a fluorinated nonporous adaptive crystalline cage (F-Cage 2) that exploits electrostatic interaction, hydrogen bonding, and F−F interactions to achieve the efficient removal of perfluorooctanoic acid (PFOA) from aqueous source phases. F-Cage 2 exhibits a high second-order k obs value of approximately 441,000 g mg −1 h −1 for PFOA and a maximum PFOA adsorption capacity of 45 mg g −1 . F-Cage 2 can decrease PFOA concentrations from 1500 to 6 ng L −1 through three rounds of flow-through purification, conducted at a flow rate of 40 mL h −1 . Elimination of PFOA from PFOA-loaded F-Cage 2 is readily achieved by rinsing with a mixture of MeOH and saturated NaCl. Heating at 80 °C under vacuum then makes F-Cage 2 ready for reuse, as demonstrated across five successive uptake and release cycles. This work thus highlights the potential utility of suitably designed nonporous adaptive crystals as platforms for PFAS remediation.

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Chiral Molecular Cage with Tunable Stereoinversion Barriers

Cited by 13 publications

References 70 publications

Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis

Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis

Molecular Face-Rotating Polyhedra: Chiral Cages Inspired by Mathematics

Fluorinated Nonporous Adaptive Cages for the Efficient Removal of Perfluorooctanoic Acid from Aqueous Source Phases

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