Publications by authors named "Andrew C-H Sue"
Chiral Self-Sorting of Flexible Covalent Organic Pillars for Adaptive Molecular Recognition.
Angew Chem Int Ed Engl
September 2025
Flexible covalent organic pillars (flex-COP-n) are introduced as a family of dual-open-ended nanotubular hosts constructed via dynamic imine condensation between pillararene-derived macrocyclic building blocks and conformationally mobile ─(CH)─ aliphatic linkers. These discrete molecular containers feature well-defined tubular channels capable of adaptive host-guest interactions. The self-assembly process exhibits a pronounced odd-even effect, yielding either enantiomeric or meso duplexes through distinct chiral self-sorting pathways.
View Article and Find Full Text PDFBiomimetic Metal-Organic Nanotubular Host for Straight-Chain Fatty Acids Recognition.
J Am Chem Soc
June 2025
Subtle structural variations among fatty acids significantly influence their biological roles and health effects. However, molecular recognition of their long, flexible, and chemically inert hydrocarbon chains remains a challenge. Inspired by natural fatty acid-binding proteins (FABPs), we designed and synthesized nanotubular metallo-cavitands, termed metal-organic pillars, through the coordination-driven assembly of pillararene-derived ligands with Ag(I) salts.
View Article and Find Full Text PDFArticle Synopsis
- Researchers are exploring macrocyclic compounds, specifically tiara[5]arenes, as crystalline adsorbents for efficient molecular sieving in environmental sustainability.
- By investigating their conformational characteristics, a range of distinct conformers was identified, highlighting their flexibility and ability to adapt to various solid-state packing arrangements.
- Despite lacking permanent porosity, these compounds show a strong tendency to selectively capture certain aromatic and olefinic solvents, achieving significant selectivity ratios in solvent mixtures.
Tracking Noncovalent Interactions of π, π-Hole, and Ion in Molecular Complexes at the Single-Molecule Level.
J Am Chem Soc
September 2024
Article Synopsis
- Noncovalent interactions involving aromatic rings, like π-stacking and π-ion interactions, are crucial for processes such as molecular recognition and electronics, but studying them experimentally is challenging due to their weak nature.
- The research focuses on interactions between different aromatic components and ions in a nonpolar solution, using electrical measurements and theoretical calculations, specifically looking at phenyl and pentafluorobenzyl groups with lithium and chloride ions.
- Findings indicate that heterogeneous interactions (like π···π-hole and π···cation) have stronger binding energies and longer lifetimes compared to homogeneous π···π interactions, and the nature of the ions affects the binding characteristics, providing insights for better manipulation of molecular systems.
Article Synopsis
- Achieved precise control over nanotubular structures by engineering a new class of single-molecule nanotubes called isoreticular covalent organic pillars (iCOPs) through dynamic covalent imine bonds.
- Developed diverse iCOPs with unique cavity shapes influenced by the choice of rigid diamine linkers, while maintaining a similar overall structure.
- Enabled tailored host-guest interactions in specific iCOP variants, which can lead to advancements in molecular recognition and purification technologies.
Article Synopsis
- Triphenylamine[3]arenes (TPA[3]s) were created using a unique cyclization reaction involving triphenylamine monomers, leading to highly efficient macrocycles with alternating carbon and nitrogen links.
- The TPA[3]s demonstrate strong electron-donating properties that result in delayed fluorescence and a considerable attraction to iodine.
- Their symmetrical design allows TPA[3]s to serve as innovative components for building complex structures like frameworks and molecular cages, broadening their potential uses in various fields.
Article Synopsis
- Molecular polyhedral cages can vary in symmetry, creating both regular shapes and chiral forms.
- Constructing chiral cages involves using stereogenic building blocks or arranging achiral components in non-symmetrical ways, making control over chirality important and challenging.
- Research inspired by Buckminster Fuller’s Face-Rotating Polyhedra (FRP) explores the synthesis of diverse stereoisomers, with specific building block selection enhancing stereoselectivity and stability through dynamic covalent assembly.
Enantioselective Self-Assembly of a Homochiral Tetrahedral Cage Comprising Only Achiral Precursors.
Angew Chem Int Ed Engl
April 2024
Article Synopsis
- Researchers are exploring how nature creates enantiomerically pure substances from achiral or racemic resources, which is not yet fully understood.
- Using a self-assembly approach, they constructed chiral tetrahedral cages by combining achiral compounds (trisamine and trisaldehyde) and harnessing intercomponent interactions to induce chirality.
- The introduction of a chiral amine during the formation of the tetrahedral cage allowed them to achieve enantioselective self-assembly, resulting in a compound with a significant enantiomeric excess while the chiral amine could be reused in multiple synthesis cycles.
Highly selective Cu detection with a naphthalimide-functionalised pillar[5]arene fluorescent chemosensor.
Org Biomol Chem
January 2024
Article Synopsis
- Ligand 1 is a modified macrocycle that acts as a highly effective fluorescent chemosensor specifically for copper ions (Cu), showcasing both monomer and excimer emissions due to its unique structure.
- When ligand 1 binds with Cu, the excimer emission decreases while the monomer emission increases, indicating a strong interaction with Cu.
- Comprehensive studies revealed a 1:1 binding ratio with a significant association constant, and the sensor has a low detection limit of 185 nM for Cu ions, supported by various analytical methods.
Article Synopsis
- Developed a new method to synthesize pillar[ ]arenes with 0 to 3 quinone groups, allowing for better control over their electron properties.
- This variation in electron richness affects how these compounds interact with silver ions, demonstrating different binding strengths.
- The resulting complexes show a notable difference in how they interact with various types of alkynes and alkenes, with terminal alkynes binding strongly while others do not.
Article Synopsis
- The study focuses on controlling chirality in dynamic molecular systems, specifically through the synthesis of a face-rotating tetrahedron (FRT) that can toggle between different chiral forms.
- Researchers found that the presence of fluoride ions can adjust the energy barrier for the FRT's transformation between enantiomers, allowing for in situ control.
- The introduction of an enantiopure phenylethanol facilitates the preferential binding to a specific conformer of the FRT, effectively inducing chirality and showcasing potential applications in asymmetric synthesis and dynamic stereochemistry.
Article Synopsis
- Researchers developed a simple method to create various -(CH-aryl/alkyl)-substituted -(pyridin-2-yl)benzamides using palladium to activate C(sp)-H bonds.
- A key intermediate, dinuclear palladacycle, was characterized using techniques like mass spectrometry and X-ray crystallography.
- The process demonstrated good versatility with functional groups and included a successful conversion of the produced compounds into -(CH-aryl)-2-aminopyridine.
Water-soluble terphen[3]arene macrocycle: a versatile reversal agent of neuromuscular blockers.
Chem Commun (Camb)
May 2023
Article Synopsis
- The study presents a new terphen[3]arene compound modified with sulfate acid ester groups, making it soluble in water.
- This compound has the ability to effectively encapsulate various neuromuscular blocking agents (NMBAs) with strong binding affinity.
- The findings suggest that this terphen[3]arene derivative could be a promising candidate for reversing the effects of NMBAs in pharmaceutical applications.
Article Synopsis
- The synthesis of a macrocycle with equatorial coordination sites was achieved through post-modification of biphen[]arene.
- By using this macrocycle as a ligand, researchers successfully created three prismatic and one octahedral metallacages by adjusting the metal acceptors' geometric structures and coordination numbers.
- The findings demonstrate that macrocycles with equatorial coordination sites can effectively serve as versatile building blocks for diverse metallacage designs and synthesis.
Handcuff-like metallo-pseudorotaxanes consisting of tiara[5]arene wheels and dimeric silver trifluoroacetate axles.
Chem Commun (Camb)
February 2023
Article Synopsis
- The tiara[5]arene (T[5]) forms a complex with silver trifluoroacetate, creating a binuclear metallo-pseudorotaxane due to several endo-cavity Ag η-arene interactions.
- Two of these enantiomeric complexes, denoted as [(CFCOAg)⊂T[5]], are linked by an additional (CFCOAg) dimer through coordination at the exo-wall.
- This leads to the formation of a distinct handcuff metallo-bis-pseudorotaxane structure when in the solid state.
Chiral nanographenes with both high fluorescence quantum yields (Φ ) and large dissymmetry factors (g ) are essential to the development of circularly polarized luminescence (CPL) materials. However, most studies have been focused on the improvement of g , whereas how to design highly emissive chiral nanographenes is still unclear. In this work, we propose a new design strategy to achieve chiral nanographenes with high Φ by helical π-extension of strongly luminescent chromophores while maintaining the frontier molecular orbital (FMO) distribution pattern.
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- The study presents a method for synthesizing 3,3'-bipyrazolo[1,5-]pyridine derivatives using a direct cross-dehydrogenative coupling of pyrazolo[1,5-]pyridine precursors, achieving high product yields of up to 94%.
- The use of palladium(II) for C-H bond activation was effective, and mechanistic insights were obtained through experimental studies and computational calculations.
- The resulting compounds were subject to further modifications, enhancing their luminescent properties and paving the way for creating custom organic luminescent materials.
Article Synopsis
- The study focuses on synthesizing a specific type of molecular structure called A1/A2-dimercapto-functionalized pillar[5]arene (Di-SH-P5).
- By incorporating thiol groups, this new molecule serves as a versatile building block for creating a dynamic combinatorial library (DCL).
- The result is a series of cyclic trimers that exhibit unique host-guest interactions, highlighting interesting properties for potential applications.
Sulfur-Phenolate Exchange: SuFEx-Derived Dynamic Covalent Reactions and Degradation of SuFEx Polymers.
Yang Chao
,
Akash Krishna
,
Muthusamy Subramaniam
,
Dong-Dong Liang
,
Sidharam P Pujari
,
Andrew C-H Sue
Angew Chem Int Ed Engl
September 2022
Article Synopsis
- The SuFEx reaction involves sulfonimidoyl fluorides and phenols, producing sulfonimidates that exhibit dynamic covalent chemistry.
- This reaction is notable for being enantiospecific, quick (completing in minutes at room temperature), and yielding high outputs.
- It has potential applications in asymmetric synthesis and sustainable polymer production, highlighting its versatility within the realm of SuFEx and similar click chemistries.
Article Synopsis
- The study demonstrates the self-assembly of a trefoil knot in water without external templates, challenging previous beliefs about imine condensation in aqueous environments.
- The process involves condensing tetraformyl precursors with chiral diamines, resulting in a knot whose chirality is determined by the diamine's configuration.
- Results show that the presence of water is crucial for forming the trefoil knot, while a weaker macrocycle structure forms in organic solvents, highlighting the role of hydrophobic effects in the process.
Article Synopsis
- A new type of pillar[6]arene called "rim-differentiated" pillar[6]arene (RD-P[6]) was successfully created using a silver trifluoroacetate template, focusing on specific isomers.
- The RD-P[6] can change its structure when it includes guest molecules, switching between different conformations.
- This advanced RD-P[6] not only can contain metal molecules but also can interact to create new materials, paving the way for innovative designs in molecular architecture and organic electronics.
Article Synopsis
- The rising popularity of pillar[5]arenes and pillar[6]arenes is due to advancements in their synthesis methods.
- Researchers aim to understand the factors that influence the formation of different sized macrocycles, such as pillar[5]arenes and pillar[6]arenes, during the Friedel-Crafts ring formation process.
- This study employs advanced computational techniques to analyze the thermodynamics and kinetics of these reactions, both with and without templating solvents.
B,N-Embedded Double Hetero[7]helicenes with Strong Chiroptical Responses in the Visible Light Region.
J Am Chem Soc
November 2021
Article Synopsis
- Scientists have developed a new type of helicene molecules that display strong optical activity across the visible spectrum, which is important for chiral optoelectronic applications.
- These B,N-embedded double hetero[7]helicenes show record high absorption dissymmetry factors (up to 0.033) and tunable circularly polarized luminescence in the red to near-infrared range.
- The enhanced chiroptical properties are attributed to the unique molecular structure with nonbonded boron and nitrogen atoms, indicating potential for advanced chiroptical materials in the future.
Article Synopsis
- Molecular face-rotating polyhedra (FRP) are complex structures, and earlier attempts to create stereocontrolled FRP resulted in losing their inner space, which limits their usefulness in host-guest interactions.
- Through a rational design method, researchers successfully developed hollow FRP with high diastereoselectivity, allowing for better manipulation of their assembly.
- By understanding and adjusting the van der Waals repulsive forces between the building blocks, this study presents a new strategy for assembling pure organic cages, enhancing the potential applications of chiral materials.
Article Synopsis
- A new type of Co-pillar[4+1]arenes was created, featuring unique upper and lower rim structures for improved functionality.
- These structures include multiple "clickable" groups, making them adaptable for various uses.
- The novel pillar[5]arene platforms are promising for building self-assembled molecular structures and exploring biological applications.