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Although mechanically interlocked molecules (MIMs) display unique properties and functions associated with their intricate connectivity, limited assembly strategies are available for their synthesis. Herein, we presented a synergistic assembly strategy based on coordination and noncovalent interactions (π-π stacking and CHâ¯π interactions) to selectively synthesize molecular closed three-link chains ([Formula: see text] links), highly entangled figure-eight knots ([Formula: see text] knots), trefoil knot ([Formula: see text] knot), and Borromean ring ([Formula: see text] link). [Formula: see text] links can be created by the strategic assembly of nonlinear multicurved ligands incorporating a furan or phenyl group with the long binuclear half-sandwich organometallic Cp*RhIII (Cp* = η5-pentamethylcyclopentadienyl) clip. However, utilizing much shorter binuclear Cp*RhIII units for union with the 2,6-naphthyl-containing ligand led to a [Formula: see text] knot because of the increased π-π stacking interactions between four consecutive stacked layers and CHâ¯π interactions. Weakening such π-π stacking interactions resulted in a [Formula: see text] knot. The universality of this synergistic assembly strategy for building [Formula: see text] knots was verified by utilizing a 1,5-naphthyl-containing ligand. Quantitative conversion between the [Formula: see text] knot and the simple macrocycle species was accomplished by adjusting the concentrations monitored by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Furthermore, increasing the stiff π-conjugated area of the binuclear unit afforded molecular Borromean ring, and this topology is a topological isomer of the [Formula: see text] link. These artificial metalla-links and metalla-knots were confirmed by single-crystal X-ray diffraction, NMR and ESI-MS. The results offer a potent strategy for building higher-order MIMs and emphasize the critical role that noncovalent interactions play in creating sophisticated topologies.
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Intervertebral disc degeneration (IDD) poses a significant health burden, necessitating a deeper understanding of its molecular underpinnings. Transcriptomic analysis reveals 485 differentially expressed genes (DEGs) associated with IDD, underscoring the importance of immune regulation. Weighted gene co-expression network analysis (WGCNA) identifies a yellow module strongly correlated with IDD, intersecting with 197 DEGs. Protein-protein interaction (PPI) analysis identifies ITGAX, MMP9 and FCGR2A as hub genes, predominantly expressed in macrophages. Functional validation through in vitro and in vivo experiments demonstrates the pivotal role of FCGR2A in macrophage polarization and IDD progression. Mechanistically, FCGR2A knockdown suppresses M1 macrophage polarization and NF-κB phosphorylation while enhancing M2 polarization and STAT3 activation, leading to ameliorated IDD in animal models. This study sheds light on the regulatory function of FCGR2A in macrophage polarization, offering novel insights for IDD intervention strategies. KEY POINTS: This study unveils the role of FCGR2A in intervertebral disc (IVD) degeneration (IDD). FCGR2A knockdown mitigates IDD in cellular and animal models. Single-cell RNA-sequencing uncovers diverse macrophage subpopulations in degenerated IVDs. This study reveals the molecular mechanism of FCGR2A in regulating macrophage polarization. This study confirms the role of the NF-κB/STAT3 pathway in regulating macrophage polarization in IDD.
Asunto(s)
Degeneración del Disco Intervertebral , Receptores de IgG , Animales , Perfilación de la Expresión Génica , Degeneración del Disco Intervertebral/genética , Degeneración del Disco Intervertebral/metabolismo , Macrófagos , FN-kappa B/genética , FN-kappa B/metabolismo , Núcleo Pulposo/metabolismo , Humanos , Ratas , Receptores de IgG/metabolismoRESUMEN
The quest for more efficient, user-friendly, and less wasteful topological transformations remains a significant challenge in the realm of postassembly modifications. In this article, high yields of two molecular trefoil knots (Rh-1, Ir-1) were obtained using ligand 3,6-bis(3-(pyridin-4-yl)phenyl)-1,2,4,5-tetrazine (L1) with reactive tetrazine units and binuclear half-sandwich organometallic units [Cp*2M2(µ-TPPHZ)(OTf)2](OTf)2 (Rh-B, M = RhIII; Ir-B, M = IrIII). 2,5-Norbornadiene was used as an inducer of the Diels-Alder click reaction to modulate rapidly and efficiently the transformation of Trefoil knots to Solomon links. However, the key to achieving this topological structural change is the subtle increase in site steric of the pyridazine fragments (L2), which allows the molecular structures to spread and bend in three-dimensional space, as confirmed by single-crystal X-ray diffraction, ESI-TOF/MS, elementary analysis and detailed solution-state NMR techniques.
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A method was developed to link two or three o-carborane moieties to form a series of carboranyl dithioester bridging ligands via inâ situ substitution of haloalkanes by tetraphenylphosphonium carboranyldithiocarboxylates. Based on these ligands, direct B-H activation without the assistance of Ag(I) and alkali was successfully achieved with half-sandwich Ir(III) substrate [Cp*IrCl2]2 to yield corresponding bimetallic or trimetallic complexes. Single crystal structure analyses of the B-H activated complexes and corresponding SnCl2-inserted derivatives confirm the selective B(3)-H activation in these complexes.
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Through a coordination-driven self-assembly method, four 4 1 2 ${4_1^2 }$ metalla-links and one tetranuclear monocycle were constructed with high selectivity and yield by adjusting the substituent species of the building blocks, as evidenced using X-ray crystallographic analysis, electrospray ionization-time-of-flight/mass spectrometry (ESI-TOF/MS), elemental analysis and detailed solution-state nuclear magnetic resonance (NMR) spectroscopy. Based on X-ray crystallographic analysis and independent gradient model analysis, a significant factor leading to the formation of 4 1 2 ${4_1^2 }$ metalla-links was the introduction of F, Cl, Br and I atoms, which generated additional weak C-Hâ â â X (X=F, Cl, Br and I) interactions. Furthermore, the dynamic conversion of 4 1 2 ${4_1^2 }$ metalla-links to monocyclic rings in methanol solution was systematically investigated using quantitative 1H NMR techniques.
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In this work, a noncoplanar terphenyl served as a building block to synthesize a novel 3,3'-substituted bipyridyl ligand (L1) which further reacted with binuclear half-sandwich units A/B, giving rise to two aesthetic 41 metalla-knots in high yields via a coordination-driven self-assembly strategy. Furthermore, given the inherent compactness of the 41 metalla-knots, it creates favorable conditions for the emergence of steric repulsion. We focused on progressively introducing nitrogen atoms featuring a lone pair of electrons (LPEs) into ligand L1 to manipulate the balance of Hâ â â H/LPEsâ â â LPEs steric repulsion during the assembly process, ultimately achieving controlled assembly from 41 metalla-knots to the pseudo-Solomon link and then to molecular tweezer-like assembly facilitated by stacking interactions. All the assemblies were well characterized by solution-state NMR techniques, ESI-TOF/MS, and single-crystal X-ray diffraction. The evolutionary process of the topological architectures is equivalent to visualizing the synergistic effect of steric hindrance and stacking interactions on structural assembly, providing a new avenue for achieving the controlled synthesis of different topologies.
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Although the synthesis of mechanically interlocked molecules has been extensively researched, selectively constructing homogeneous linear [4]catenanes remains a formidable challenge. Here, we selectively constructed a homogeneous linear metalla[4]catenane in a one-step process through the coordination-driven self-assembly of a bidentate benzothiadiazole derivative ligand and a binuclear half-sandwich rhodium precursor. The formation of metalla[4]catenanes was facilitated by cooperative interactions between strong sandwich-type π-π stacking and non-classical hydrogen bonds between the components. Moreover, by modulating the aromatic substituents on the binuclear precursor, two homogeneous metalla[2]catenanes were obtained. The molecular structures of these metallacatenanes were unambiguously characterized by single-crystal X-ray diffraction analysis. Additionally, reversible structural transformation between metal-catenanes and the corresponding metallarectangles could be achieved by altering their concentration, as confirmed by mass spectrometry and NMR spectroscopy studies.
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Facilitated by multiple stacking interactions between components, two kinds of metalla-links containing molecular Borromean rings (623 links) and head-to-tail cyclic [3]catenanes (613 links), as isomers, were constructed in high yield by introducing tri-µ-methoxyl-dinuclear complexes [(Cp*M)2(µ-OCH3)3][OTf] (M = RhIII or IrIII, Cp* = η5-pentamethylcyclopentadienyl, OTf = triflate) as unusual cationic guests during coordination-driven assembly. The topology of these intricate structures was controlled by strategically selecting two dipyridyl ligands that differ in their coordination orientations, as evidenced by X-ray crystallography and electrospray ionization-time-of-flight/mass spectrometry analysis. The behavior of the abovementioned metalla-links in solution was monitored and further studied by the detailed NMR techniques.
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We have successfully constructed a chiral linear [3]catenane stereoselectively by coordination-driven self-assembly using a ditopic monodentate ligand containing l-valine residues with a binuclear half-sandwich organometallic rhodium(III) unit. Furthermore, by increasing the steric hindrance of the amino acid residues in the ligand, a chiral [2]catenane was obtained, which can be regarded as the factor catenane of the chiral linear [3]catenane from a topological viewpoint. Notably, the resulting molecular catenanes all exhibit complex coconformational mechanical helical chirality and planar chirality ascribed to the point chirality of the ligands. Linear [3]catenanes and [2]catenanes with the opposite chirality can be obtained by using ligands containing the corresponding d-amino acid residues, which have been confirmed by single-crystal X-ray diffraction, NMR, mass spectrometry, and circular dichroism spectroscopy.
Asunto(s)
Catenanos , Catenanos/química , Ligandos , Antracenos , Cristalografía por Rayos XRESUMEN
The utilization of carboranes in supramolecular chemistry has attracted considerable attention. The unique spatial configuration and weak interaction forces of carboranes can help to explore the properties of supramolecular complexes, particularly via host-guest chemistry. Additionally, certain difficulties encountered in carborane developmentâsuch as controlled B-H bond activationâcan be overcome by judiciously selecting metal centers and their adjacent ligands. However, few studies are being conducted in this nascent research area. With advances in this field, novel carborane-based supramolecular complexes will likely be prepared, structurally characterized, and intrinsically investigated. To expedite these efforts, we present major findings from recent studies, including π-π interactions, host-guest associations, and steric effects, which have been leveraged to implement a regioselective process for activating B(2,9)-, B(2,8)-, and B(2,7)-H bonds of para-carboranes and B(4,7)-H bonds of ortho-carboranes. Future studies should clarify the unique weak interactions of carboranes and their potential for enhancing the utility of supramolecular complexes. Although carboranes exhibit several unique weak interactions (such as dihydrogen-bond [Bδ+-Hδ-···Hδ+-Cδ-], Bδ+-Hδ-···M+, and Bδ+-Hδ-···π interactions), the manner in which they can be utilized remains unclear. Supramolecular complexes, particularly those based on host-guest chemistry, can be utilized as a platform for demonstrating potential applications of these weak interactions. Owing to the importance of alkane separation, applications related to the recognition and separation of alkane isomers via dihydrogen-bond interactions are primarily summarized. Advances in the research of unique weak interactions in carboranes will certainly lead to more possibilities for supramolecular chemistry.
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Developing novel assembly methods for supramolecular compounds has long been a research challenge. Herein, we describe how to integrate the B-C coupling reaction and "cage walking" process into coordination self-assembly to construct supramolecular cages. In this strategy, dipyridine linkers containing alkynes react with the metallized carborane backbone through B-C coupling and then "cage walking" resulting in metallacages. However, dipyridine linkers without alkynyl groups can form only metallacycles. We can regulate the size of metallacages based on the length of the alkynyl bipyridine linkers. When tridentate-pyridine linkers participate in this reaction, a new type of ravel is formed. The metallization of carboranes, the B-C coupling reaction, and especially the "cage walking" process of carborane cages play a vital role in this reaction. This work provides a promising principle for the synthesis of metallacages and opens up a novel opportunity in the supramolecular field.
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A series of Cp* Rh-based discrete architectures was constructed by selecting four ether bipyridyl ligands and three half-sandwich rhodium(III) bimetallic construction units, respectively. This study demonstrates a strategy for making the transition from a binuclear D-shaped ring to a tetranuclear [2]catenane by adjusting the length of bipyridyl ligands. In addition, changing the position on the naphthyl group of the bipyridyl ligand from 2,6- to 1,5-position substitution can realize the selective synthesis of [2]catenane and Borromean rings under similar conditions. The above-mentioned constructions have been determined via X-ray crystallographic analysis, detailed NMR techniques, electrospray ionization-time-of-flight/mass spectrometry analysis, and elemental analysis.
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By exploiting coordination-driven self-assembly, high yields of two 818 molecular metalla-knots could be obtained using a thiazole-moiety-containing asymmetric dipyridyl ligand 2-(pyridin-4-yl)-5-(pyridin-4-ylethynyl)benzo[d]thiazole (L1 ), as confirmed using X-ray crystallographic analysis, electrospray ionization-time-of-flight/mass spectrometry (ESI-TOF/MS), and detailed liquid-state nuclear magnetic resonance (NMR) spectroscopy. To modulate the self-assembled structures, m-chloroperbenzoic acid (m-CPBA) was utilized to oxidize thiazole-based ligand L1 to N-thiazole-oxide-based ligand 2-(pyridin-4-yl)-5-(pyridin-4-ylethynyl)benzo[d]thiazole 3-oxide (L2 ), which enabled the selective construction of the corresponding tetranuclear macrocycles. Notably, two molecular metalla-knots could be topologically transformed from 818 knots to simple monocycles because the L1 alkyne bond was inert toward m-CPBA, as confirmed by liquid-state NMR spectroscopy, ESI-TOF/MS, and elemental analysis.
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We report herein a series of organometallic Borromean rings (BRs) and [2]catenanes prepared from benzobiscarbene ligands. The reaction of dinickel complexes of the benzobiscarbenes 1 a-1 c with a thiazolothiazole bridged bipyridyl ligand L2 led by self-assembly to a series of organometallic BRs. Solvophobic effects played a crucial role in the formation and stability of the interlocked species. The stability of BRs is related to the N-alkyl substituents at the precursors 1 a-1 c, where longer alkyl substitutes improve stability and inter-ring interactions. Solvophobic effects are also important for the stability of [2]catenanes prepared from 1 a-1 c and a flexible bipyridyl ligand L3 . In solution, an equilibrium between the [2]catenanes and their macrocyclic building blocks was observed. High proportions of [2]catenanes were obtained in concentrated solutions or polar solvents. The proportion of [2]catenanes in solution could be further enhanced by lengthening of the N-alkyl substitutes.
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Intricately interwoven topologies are continually being synthesized and are ultimately equally versatile and significant at the nanoscale level; however, reports concerning ravel structures, which are highly entwined new topological species, are extremely rare and fraught with tremendous synthesis challenges. To solve the synthesis problem, a tetrapodontic pyridine ligand L1 with two types of olefinic bond units and two Cp*M-based building blocks (E1, M=Rh; E2, M=Ir) featuring large conjugated planes was prepared to perform the self-assembly. Two unprecedented [5+10] icosanuclear molecular 4-ravels containing four crossings were obtained by parallel-displaced πâ â â π interactions in a single-step strategy. Remarkably, reversible structural transformations between the 4-ravel and the corresponding metallocage could be realized by concentration changes and solvent- and guest-induced effects. X-ray crystallographic data and NMR spectroscopy provide full confirmation of these phenomena.
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Constructing the backbones of polymers with metal atoms is an attractive strategy to develop new functional polymeric materials, but it has yet to be studied due to synthetic challenges. Here, metal atoms are interconnected as the backbones of polymers to yield metal-backboned polymers (MBPs). Rational design of multidentate ligands synthesized via an efficient iterative approach leads to the successful construction of a series of nickel-backboned polymers (NBPs) with well-defined lengths and up to 21 nickel atoms, whose structures are systematically confirmed. These NBPs exhibit strong and length-depended absorption with narrow band gaps, offering promising applications in optoelectronic devices and semiconductors. We also demonstrate the high thermal stability and solution processsability of such nickel-backboned polymers. Our results represent a new opportunity to design and synthesize a variety of new metal-backboned polymers for promising applications in the future.
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The specific recognition and separation of alkanes with similar molecular structures and close boiling points face significant scientific challenges and industrial demands. Here, rectangular carborane-based metallacycles were designed to selectively encapsulate n-pentane from n-pentane, iso-pentane, and cyclo-pentane mixtures in a simple-to-operate and more energy-efficient way. Metallacycle 1, bearing 1,2-di(4-pyridyl) ethylene, can selectively separate n-pentane from these three-component mixtures with a purity of 97%. The selectivity is ascribed to the capture of the preferred guest with matching size, C-H···π interactions, and potential B-Hδ-···Hδ+-C interactions. Besides, the removal of n-pentane gives rise to original guest-free carborane-based metallacycles, which can be recycled without losing performance. Considering the variety of substituted carborane derivatives, metal ions, and organic linkers, these new carborane-based supramolecular coordination complexes (SCCs) may be broadly applicable to other challenging recognition and separation systems with good performance.
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Herein, we have successfully achieved the stereoselective synthesis of two chiral radial [5]catenanes in a single step through the self-assembly of bidentate ligands containing l-alanine residues and binuclear half-sandwich organometallic rhodium(III)/iridium(III) clips. Remarkably, these two chiral radial [5]catenanes exhibit complex stereochemical structures as revealed by single-crystal X-ray diffraction. The eight binuclear units and eight bidentate ligands in their solid-state structures all exhibit a single planar chirality, and the interlocking between molecular macrocycles exhibits a single co-conformational mechanical helical chirality. This indicates that the introduction of the point chirality in the ligands enables the efficient stereoselective construction of mechanically interlocked molecules. Furthermore, by using ligands containing d-alanine residues, radial [5]catenanes with the opposite planar chirality and opposite co-conformational mechanical helical chirality have also been obtained.
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Separation of light hydrocarbons (C1-C9) represents one of the "seven chemical separations to change the world". Boron clusters can potentially play an important role in chemical separation, due to their unique three-dimensional structures and their ability to promote a potentially rich array of weak noncovalent interactions. Herein, we report the rational design of metallacages with carborane functionality and cooperative dihydrogen binding sites for the highly selective capture of cyclohexane molecules. The metallacage 1, bearing the ligand 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT), can produce cyclohexane with a purity of 98.5% in a single adsorption-desorption cycle from an equimolar mixture of benzene and cyclohexane. In addition, cyclohexene molecules can be also encapsulated inside the metallacage 1. This selective encapsulation was attributed to spatial confinement effects, C-H···π interactions, and particularly dihydrogen-bond interactions. This work suggests exciting future applications of carborane cages in supramolecular chemistry for the selective adsorption and separation of alkane molecules and may open up a new research direction in host-guest chemistry.
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We report a design strategy for integrative assembly of heteromeric [2]catenanes. The design focuses on the shape and functional group match of two different metalla-rectangles. A series of dipyridyl ligands with different lengths, widths and functional groups were designed and used for assembly experiments. Six heteromeric [2]catenanes were obtained both by direct mixture of two pre-assembled metalla-rectangles and one-pot three-component self-assembly. Multiple analytic methods were employed to characterize the catenanes, including single crystal X-ray diffraction analysis, NMR spectroscopy, mass spectroscopy and elemental analysis.