Cu(II)-Mediated Sulfonylation of (Hetero)arenes with TosMIC Using Monodentate Directing Groups.

Monodentate chelation-assisted direct ortho-C-H sulfonylation of (hetero)arenes using TosMIC as the novel sulfonylating reagent has been developed. A broad range of substrates, including indolines, indoles, 2-phenylpyridines, and others were well tolerated to afford the corresponding products in moderate to good yields. Mechanistic studies revealed that the sulfonyl radical might be involved. Inspired by the above discovery, preliminary para-C-H sulfonylation of naphthalene substrate was also successfully realized. The current protocol featured with cheap metal catalysis, good functional group compatibility, and operational convenience.

Hourglass-Shaped Nanocages with Concaved Structures Based on Selective Self-Complementary Coordination Ligands and Tunable Hierarchical Self-Assembly.

Three-dimensional (3D) structures constructed via coordination-driven self-assemblies have recently garnered increasing attention due to the challenges in structural design and potential applications. In particular, developing new strategy for the convenient and precise self-assemblies of 3D supramolecular structures is of utmost interest. Introducing the concept of self-coordination ligands, herein the design and synthesis of two meta-modified terpyridyl ligands with selective self-complementary coordination moiety are reported and their capability to assemble into two hourglass-shaped nanocages SA and SB is demonstrated. Within these 3D structures, the meta-modified terpyridyl unit preferably coordinates with itself to serve as concave part. By changing the arm length of the ligands, hexamer (SA) and tetramer (SB) are obtained respectively. In-depth studies on the assembly mechanism of SA and SB indicate that the dimers could be formed first via self-complementary coordination and play crucial roles in controlling the final structures. Moreover, both SA and SB can go through hierarchical self-assemblies in solution as well as on solid-liquid interface, which are characterized by transmission electron microscope (TEM) and scanning tunneling microscopy (STM). It is further demonstrated that various higher-order assembly structures can be achieved by tuning the environmental conditions.

Construction of 1,3,5-Triazine-Based Prisms and Their Enhanced Solid-State Emissions.

In this study, two trigonal prisms based on the 1,3,5-triazine motif (SA and SB), distinguished by hydrophobic groups, were prepared by the self-assembly of tritopic terpyridine ligands and Zn(II) ions. SA and SB exhibited high luminescence efficiencies in the solid state, overcoming the fluorescence quenching of the 1,3,5-triazine group caused by π-π interactions. Notably, SA and SB exhibited different luminescence behaviors in the solution state and aggregation state. SB with 12 alkyl chains exhibited extremely weak fluorescence in a dilute solution, but its fluorescence intensity and photoluminescence quantum yield (PLQY) were significantly enhanced in the aggregated state (with the increase in the water fraction), especially in the solid state. Different from the gradually enhanced efficiency of SB, the PLQY of SA gradually decreased with the increase in aggregation but still maintained a high luminescence efficiency. These two complexes exhibited different modes to solve the fluorescence quenching of 1,3,5-triazine in the solid state. The hierarchical self-assembly of SB exhibited nanorods owing to the hydrophobic interactions of alky chains, while SA aggregated into spheres under the influence of π-π interactions.

Amine-Imine Nickel Catalysts with Pendant O-Donor Groups for Ethylene (Co)Polymerization.

The introduction of a secondary interaction is an efficient strategy to modulate transition-metal-catalyzed ethylene (co)polymerization. In this contribution, O-donor groups were suspended on amine-imine ligands to synthesize a series of nickel complexes. By adjusting the interaction between the nickel metal center and the O-donor group on the ligands, these nickel complexes exhibited high activities for ethylene polymerization (up to 3.48 × 106 gPE·molNi-1·h-1) with high molecular weight up to 5.59 × 105 g·mol-1 and produced good polyethylene elastomers (strain recovery (SR) = 69-81%). In addition, these nickel complexes can catalyze the copolymerization of ethylene with vinyl acetic acid, 6-chloro-1-hexene, 10-undecylenic, 10-undecenoic acid, and 10-undecylenic alcohol to prepare the functionalized polyolefins.

Tailored Supramolecular Cage for Efficient Bio-Labeling.

Fluorescent chemosensors are powerful imaging tools used in a broad range of biomedical fields. However, the application of fluorescent dyes in bioimaging still remains challenging, with small Stokes shifts, interfering signals, background noise, and self-quenching on current microscope configurations. In this work, we reported a supramolecular cage (CA) by coordination-driven self-assembly of benzothiadiazole derivatives and Eu(OTf)3. The CA exhibited high fluorescence with a quantum yield (QY) of 38.57%, good photoluminescence (PL) stability, and a large Stokes shift (153 nm). Furthermore, the CCK-8 assay against U87 glioblastoma cells verified the low cytotoxicity of CA. We revealed that the designed probes could be used as U87 cells targeting bioimaging.

Synthesis of a Tetrahedral Metal-Organic Supramolecular Cage with Dendritic Carbazole Arms.

In recent years, incredible endeavors have been devoted to the design and self-assembly of discrete metal-organic cages (MOCs) with expanding intricacy and functionality. The controlled synthesis of metal-organic supramolecular cages with large branched chains remains an interesting and challenging work in supramolecular chemistry. Herein, a tetrahedral metal-organic supramolecular cage (ZnII4L4) containing 12 dendritic carbazole arms is unprecedentedly constructed through coordination-driven subcomponent self-assembly and characterized in different ways. Interestingly, tetrahedral supramolecular Cage-1 exhibited the potential for aggregation-induced emission (AIE) performance and stimulus-responsive luminescence features, and it achieved color-tunable photoluminescence due to the introduction of dendritic carbazole arms. Crucially, owing to the great photophysical properties of Cage-1 in solution, Cage-1 was enabled to act as a fluorescent ink for the vapor-responsive recording and wiping of information.

The Novel Function of Unsymmetrical Chiral CCN Pincer Nickel Complexes as Chemotherapeutic Agents Targeting Prostate Cancer Cells.

We report that the pincer nickel complexes display prostate cancer antitumor properties through inhibition of cell proliferation. Notably, they display better antitumor properties than cisplatin. Mechanistic studies reveal that these pincer nickel complexes trigger cell apoptosis, most likely due to cell cycle arrest. Interestingly, these complexes also inhibit androgen receptor (AR) and prostate-specific antigen (PSA) signaling, which are critical for prostate cancer survival and progression. Our study reveals a novel function of pincer nickel complexes as potential therapeutic drugs in prostate cancer.

NaOH-Mediated Direct Synthesis of Quinoxalines from o-Nitroanilines and Alcohols via a Hydrogen-Transfer Strategy.

A NaOH-mediated sustainable synthesis of functionalized quinoxalines is disclosed via redox condensation of o-nitroamines with diols and α-hydroxy ketones. Under optimized conditions, various o-nitroamines and alcohols are well tolerated to generate the desired products in 44-99% yields without transition metals and external redox additives.

Iron-Mediated Selective Sulfonylmethylation of Aniline Derivatives with p-Toluenesulfonylmethyl Isocyanide (TosMIC).

An iron-mediated highly selective C-H sulfonylmethylation of aniline derivatives with p-toluenesulfonylmethyl isocyanide in a mixture solvent of H2O and PEG400 under an Ar atmosphere has been realized. This transformation proceeds with operational convenience, use of earth-abundant metal catalyst and nontoxic media, broad substrate scope, and good functional group tolerance. The current methodology could be applied to the regioselective C-H sulfonylmethylation of indolines, tetrahydroquinolines, and tertiary anilines.

Self-Assembly of Metallo-Supramolecules under Kinetic or Thermodynamic Control: Characterization of Positional Isomers Using Scanning Tunneling Spectroscopy.

Coordination-driven self-assembly has been extensively employed to construct a variety of discrete structures as a bottom-up strategy. However, mechanistic understanding regarding whether self-assembly is under kinetic or thermodynamic control is less explored. To date, such mechanistic investigation has been limited to distinct, assembled structures. It still remains a formidable challenge to study the kinetic and thermodynamic behavior of self-assembly systems with multiple assembled isomers due to the lack of characterization methods. Herein, we use a stepwise strategy which combined self-recognition and self-assembly processes to construct giant metallo-supramolecules with 8 positional isomers in solution. With the help of ultrahigh-vacuum, low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy, we were able to unambiguously differentiate 14 isomers on the substrate which correspond to 8 isomers in solution. Through measurement of 162 structures, the experimental probability of each isomer was obtained and compared with the theoretical probability. Such a comparison along with density functional theory (DFT) calculation suggested that although both kinetic and thermodynamic control existed in this self-assembly, the increased experimental probabilities of isomers compared to theoretical probabilities should be attributed to thermodynamic control.

Synthesis of Metallopolymers and Direct Visualization of the Single Polymer Chain.

During the past few decades, the study of the single polymer chain has attracted considerable attention with the goal of exploring the structure-property relationship of polymers. It still, however, remains challenging due to the variability and low atomic resolution of the amorphous single polymer chain. Here, we demonstrated a new strategy to visualize the single metallopolymer chain with a hexameric or trimeric supramolecule as a repeat unit, in which Ru(II) with strong coordination and Fe(II) with weak coordination were combined together in a stepwise manner. With the help of ultrahigh-vacuum, low-temperature scanning tunneling microscopy (UHV-LT-STM) and scanning tunneling spectroscopy (STS), we were able to directly visualize both Ru(II) and Fe(II), which act as staining reagents on the repeat units, thus providing detailed structural information for the single polymer chain. As such, the direct visualization of the single random polymer chain is realized to enhance the characterization of polymers at the single-molecule level.

Ruthenium-Catalyzed C(sp2)-H Bond Bisallylation with Imidazopyridines as Directing Groups.

A Ru(II)-catalyzed bisallylation of imidazopyridines with vinylcyclopropanes or vinyl cyclic carbonate has been successfully realized. Notably, pharmacophore imidazopyridine was utilized as an intrinsic directing group, which gave access to value-added bisallylated products in high yields via double tandem C-H and C-C/C-O activation. The current methodology was featured with broad substrate scope, good functional group compatibility, and operational simplicity.

Temperature-Controlled Chalcogenation and Chalcogenocyanation of Imidazopyridines in Water under Transition Metal-Free Conditions.

A sustainable and transition metal-free approach for C3 chalcogenation and chalcogenocyanation of imidazopyridines with KXCN (X = S or Se) has been developed under mild conditions. Importantly, this reaction was performed in the presence of catalytic iodine in aqueous medium, which afforded either chalcogenated or chalcogenocyanated imidazopyridines under temperature control. The current protocol featured a broad substrate scope, transition metal-free and organic solvent-free conditions, operational convenience, and gram-scale production.

Rh(III)-Catalyzed C-H Cyanation of 2H-Indazole with N-Cyano-N-phenyl-p-toluenesulfonamide.

A Rh(III)-catalyzed direct cyanation of 2H-indazoles with N-cyano-N-phenyl-p-toluenesulfonamide has been realized via a chelation-assisted strategy. The methodology enables regioselective access to various ortho-cyanated phenylindazoles in good yields with a broad substrate scope and good functional group compatibility. The obtained cyanated indazoles could further be converted into other value-added chemicals. Importantly, the current protocol is featured with several characteristics, including a novel cyanating agent, good regioselectivity, and operational convenience.

Cu-Catalyzed Direct C7 Sulfonylation of Indolines with Arylsulfonyl Chlorides.

An efficient Cu-catalyzed direct sulfonylation of indolines with easily accessible sulfonyl chlorides has been realized under an air atmosphere via a chelation-assisted strategy. This protocol exhibits several unique characteristics, including broad substrate scope, good functional group tolerance, and operational convenience, which enable a regioselective access to a variety of C-7 functionalized indoline scaffolds in moderate to good yields. The mechanistic study reveals that the sulfonyl radical might be involved in this transformation.

Combining Synthesis and Self-Assembly in One Pot To Construct Complex 2D Metallo-Supramolecules Using Terpyridine and Pyrylium Salts.

Multicomponent self-assembly in one pot provides an efficient way for constructing complex architectures using multiple types of building blocks with different levels of interactions orthogonally. The preparation of multiple types of building blocks typically includes tedious synthesis. Here, we developed a multicomponent synthesis/self-assembly strategy, which combined covalent interaction (C-N bond, formed through condensation of pyrylium salt with primary amine) and metal-ligand interaction (N → Zn bond, formed through 2,2':6',2″-terpyridine-Zn coordination) in one pot. The high compatibility of this pair of interactions smoothly and efficiently converted three and four types of components into the desired complex structures, which are supramolecular Kandinsky Circles and spiderwebs, respectively.

Assembling Pentatopic Terpyridine Ligands with Three Types of Coordination Moieties into a Giant Supramolecular Hexagonal Prism: Synthesis, Self-Assembly, Characterization, and Antimicrobial Study.

Three dimensional (3D) supramolecules with giant cavities are attractive due to their wide range of applications. Herein, we used pentatopic terpyridine ligands with three types of coordination moieties to assemble two giant supramolecular hexagonal prisms with a molecular weight up to 42 608 and 43 569 Da, respectively. Within the prisms, two double-rimmed Kandinsky Circles serve as the base surfaces as well as the templates for assisting the self-sorting during the self-assembly. Additionally, hierarchical self-assembly of these supramolecular prisms into tubular-like nanostructures was fully studied by scanning tunneling microscopy (STM) and small-angle X-ray scattering (SAXS). Finally, these supramolecular prisms show good antimicrobial activities against Gram-positive pathogen methicillin-resistant Staphylococcus aureus (MRSA) and Bacillus subtilis (B. subtilis).

Copper-Catalyzed Double Thiolation To Access Sulfur-Bridged Imidazopyridines with Isothiocyanate.

A copper(I)-catalyzed sulfur-bridged dimerization of imidazopyridines has been developed using isothiocyanate as the sulfur source. This method enables a switchable synthesis of bis(imidazo[1,2- a]pyridin-3-yl)sulfanes or bis(2-(imidazo[1,2- a]pyridin-2-yl)phenyl)sulfanes in the presence of 4-dimethylaminopyridine (DMAP) or K2CO3 when different imidazopyridines were employed. Under optimized conditions, a variety of sulfur-bridged imidazopyridines were obtained in good yields. Moreover, thiourea was proved to be the key intermediate under catalytic system A.

Ditopic Chiral Pineno-Fused 2,2':6',2″-Terpyridine: Synthesis, Self-Assembly, and Optical Properties.

The syntheses of 4'-substituted chiral 2,2':6',2″-terpyridine (tpy) ligands with predetermined configurations and directionalities are rather limited in the supramolecular chemistry field. In this study, a carbazole-linked ditopic chiral ligand L was synthesized using 4'-bromo-substituted pineno-fused tpy 5 as the precursor. Upon complexation with Cd(NO3)2·4H2O and Zn(NO3)2·6H2O, two enantiomerically pure metallosupramolecules, [Cd3L3] and [Zn4L4], have been self-assembled and characterized by NMR, electrospray ionization-mass spectrometry, traveling wave ion mobility-mass spectrometry, and DOSY analysis. In addition, their optical properties are characterized by UV-vis, fluorescence, circular dichroism, and circularly polarized luminescence, suggesting an efficiency transmission and amplification of chirality from the ligand to metal center via self-assembly.

Oxidative sulfonamidomethylation of imidazopyridines utilizing methanol as the main C1 source.

An efficient one pot, three component synthesis of C3 sulfonamidomethylated imidazopyridines has been disclosed under metal-free conditions, which utilized the commercially available and renewable reagent methanol as the main methylene source. A wide range of substituted imidazopyridines and sulfamides/amines were well tolerated to afford the corresponding products in up to 92% yield. In the isotopic labelling experiment, it was found that a minor part of the methylene also originated from DTBP. Moreover, the radical scavenger reactions were conducted, which suggested that a free-radical mechanism was probably not involved. The current methodology featured several advantages, including broad substrate scope, good functional group tolerance and high reaction efficiency.