Nickel-Catalyzed Suzuki-Miyaura Coupling in Water for the Synthesis of 2-Aryl Allyl Phosphonates and Sulfones

An operationally simple and green protocol using a NiSO4·6H2O/cationic 2,2'-bipyridyl ligand system as a water-soluble catalyst for the coupling of arylboronic acids with (2-haloallyl)phosphonates and (2-haloallyl)sulfones in water under air was developed. The reaction was performed at 120 °C with arylboronic acids (2 mmol) and (2-haloallyl)phosphonates or sulfones (1 mmol) in the presence of 5 mol % of the Ni catalytic system in a basic aqueous solution for 1 h, giving the corresponding 2-aryl allyl phosphonates or sulfones in good to excellent yields. This reaction features the use of an abundant transition metal as a catalyst in water and exhibits high functional group tolerance, rendering it an eco-friendly procedure.

Amyloid Modifier SERF1a Accelerates Alzheimer's Amyloid-β Fibrillization and Exacerbates the Cytotoxicity

Alzheimer's disease (AD) is a devastating, progressive neurodegenerative disease affecting the elderly in the world. The pathological hallmark senile plaques are mainly composed of amyloid-β (Aβ), in which the main isoforms are Aβ40 and Aβ42. Aβ is prone to aggregate and ultimately forms amyloid fibrils in the brains of AD patients. Factors that alter the Aβ aggregation process have been considered to be potential targets for treatments of AD. Modifier of aggregation 4 (MOAG-4)/small EDRK-rich factor (SERF) was previously selected from a chemical mutagenesis screen and identified as an amyloid modifier that promotes amyloid aggregation for α-synuclein, huntingtin, and Aβ40. The interaction and effect of yeast ScSERF on Aβ40 were previously described. Here, we examined the human SERF1a effect on Aβ40 and Aβ42 fibrillization by the Thioflavin T assay and found that SERF1a accelerated Aβ fibrillization in a dose-dependent manner without changing the fibril amount and without incorporation. By Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM), we found that SERF1a altered the secondary structures and the morphology of Aβ fibrils. The electrospray ionization mass spectrometry (ESI-MS) and analytical ultracentrifugation (AUC) results showed that SERF1a binds to Aβ in a 1:1 stoichiometry. Moreover, the NMR study showed that SERF1a interacts with Aβ via its N-terminal region. Cytotoxicity assay demonstrated that SERF1a enhanced toxicity of Aβ intermediates, and the effect can be rescued by SERF1a antibody. Overall, our study provides the underlying molecular mechanism for the SERF1a effect on Aβ fibrillization and facilitates the therapeutic development of AD.

Covalent bonding of quaternary ammonium compounds and zwitterionic polymer functional layers on polydimethylsiloxane against Escherichia Coli adhesion

Quaternary ammonium compounds (QACs) are recognized by the World Health Organization as a useful disinfectant against microbes. The synergistic effect of zwitterionic polymers with QACs as antimicrobial agents rather than QACs alone is yet to be investigated. A potential strategy is the use of covalent bonding to halt the release of minute antibacterials and a hierarchy of functional layers to detain and annihilate microbes. The strategy was tested on a polydimethylsiloxane (PDMS) surface on which quaternized poly(2-dimethylaminoethyl methacrylate) (qDMA+) and sulfobetaine (SBMA) were hierarchically functionalized. Attenuated total reflectance Fourier transform infrared analysis confirmed the quaternization of DMA to qDMA+, grafting of qDMA + on PDMS (PDMS-qDMA+), and grafting of the SBMA overlayer on PDMS-qDMA+ (PDMS-qDMA+-SB). Contact angle measurement showed that PDMS-qDMA + exhibited the lowest contact angle (26.2 ± 2.9°) compared with the hydrophobic PDMS (115.2 ± 1.6°), but that of PDMSqDMA+-SB increased to 56.3 ± 1.3°. The Escherichia coli survival count revealed that PDMS-qDMA+ and PDMS-qDMA+-SB exhibited significantly greater bactericidal ability than PDMS. Confocal laser scanning microscopy revealed fewer dead bacteria on PDMS-qDMA+-SB than on PDMS-qDMA+. Scanning electron microscopy demonstrated that E. coli was disintegrated on the functionalized surface via dual-end cell lysis. To the best of our knowledge, this is the first observation of this type of process. The results confirmed the potent antibacterial and cell disruption activities of the qDMA+ and SBMA modified PDMS surface.

Sequential self-assembly of calix[4]resorcinarene-based heterobimetallic Cd8Pt8 nano-Saturn complexes

A rational molecular design strategy is introduced for selective metal-ligand coordination, enabling the quantitative self-assembly of heterobimetallic nano-Saturn complexes. During the sequential multicomponent self-assembly, the CdII ions and organometallic trans-PtII motifs demonstrate preferential binding to specific ligands. The pre-designed directive interactions allow for precise control over the structural characteristics.

Structural Switching of a Distorted Trigonal Metal-Organic Cage to a Tetragonal Cage and Singlet Oxygen Mediated Oxidations

Construction of metal-organic cages with unique architecture and guest binding abilities is highly desirable. Herein, we report the synthesis of a distorted trigonal cage 1 from a twisted tetratopic ligand (L) and a Pd(II) acceptor. Surprisingly, 1 exhibited a complete structural reorganization of its building units in presence of C70 and C60 to form guest-encapsulated tetragonal cages, (C70)2@2 and (C60)2@2, respectively. These guest-bound cages were found to be potential 1O2 generators and the former effectively catalyzed two different varieties of 1O2-mediated oxidation reactions.

A 5.3 nm giant metal-organic cage and its supramolecular gel for the formation of dye molecular ionic pairs

A terpyridine-based supramolecular cage was successfully synthesized by the self-assembly of a hexapodal metal-organic ligand with Zn²⁺. This metallo-cage exhibited two large parallel planes on the top and bottom with diameters close to 6 nm and a face-to-face distance close to 3.5 nm, thus possessing a large cavity. Electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR), two-dimensional nuclear Overhauser (2D-NOESY), and diffusion-ordered (DOSY) spectroscopies as well as transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements, unambiguously supported the formation of a supramolecular cage. Furthermore, the corresponding metal-organic gel was felicitously prepared in CH₃CN/H₂O and displayed good adsorption performance for dye molecules.

Iron-Catalyzed Cadiot-Chodkiewicz Coupling with High Selectivity in Water under Air

An iron-based catalytic system was developed for the cross-coupling of 1-bromoalkynes with terminal alkynes to selectively generate unsymmetrical 1,3-butadiynes in water under air. It was found that a combination of 1-bromoalkynes derived from less acidic terminal alkynes with more acidic counterparts would greatly enhance yields and selectivity for unsymmetrical 1,3-butadiynes. The reaction was also applicable for the synthesis of unsymmetrical 1,3,5-hexatriynes through coupling of 1-bromoalkynes and trimethylsilyl-protected 1,3-butadiynes in a one-pot manner.

{ScnGdn} Heterometallic Rings: Tunable Ring Topology for Spin-Wave Excitations

Data carriers using spin waves in spintronic and magnonic logic devices offer operation at low power consumption and free of Joule heating yet requiring noncollinear spin structures of small sizes. Heterometallic rings can provide such an opportunity due to the controlled spin-wave transmission within such a confined space. Here, we present a series of {Sc_nGd_n} (n = 4, 6, 8) heterometallic rings, which are the first Sc-Ln clusters to date, with tunable magnetic interactions for spin-wave excitations. By means of time- and temperature-dependent spin dynamics simulations, we are able to predict distinct spin-wave excitations at finite temperatures for Sc₄Gd₄, Sc₆Gd₆, and Sc₈Gd₈. Such a new model is previously unexploited, especially due to the interplay of antiferromagnetic exchange, dipole-dipole interaction, and ring topology at low temperatures, rendering the importance of the latter to spin-wave excitations.

Preparation and conformational analysis of polyproline tri-helix macrocycle nanoscaffolds of varied sizes

Ligand patterns at the nanoscale are essential in modulating biological recognition and signaling through binding to receptor oligomers. Biocompatible nanoscaffolds that allow precise control of multiple ligand presentation would be of great use in manipulating cellular processes and understanding membrane receptor biology. We have previously developed tri-helix and tetra-helix macrocycle scaffolds based on the Pro9 peptide helix to control ligand arrangements that can selectively target receptor oligomers. A better understanding of the structure of these macromolecules would significantly reduce the difficulty in designing matching ligand positions for target receptors. In this work, we expand the arsenal of ligand patterns by preparing polyproline tri-helix macrocycle scaffolds of different sizes. These synthetic nanoscaffolds composed of peptide helices ranging from Pro6 to Pro12 also allowed us to systematically investigate their properties. With a combination of circular dichroism spectroscopy and ion mobility spectrometry-mass spectrometry (IMS-MS), the measurement for varied sizes of these scaffolds indicated the connecting dihedral angle between both ends of the helix affects the strain in the cyclic scaffold. The experimental collision cross section obtained from IMS-MS favors a propeller model for the helix arrangements. The results not only contribute conformational insights for the polyproline tri-helix system, but also provide precious information for the future design and synthesis of cyclic nanostructures based on peptide helices.

Russian-Doll-Like Molecular Cubes

Nanosized cage-within-cage compounds represent a synergistic molecular self-assembling form of three-dimensional architecture that has received particular research focus. Building multilayered ultralarge cages to simulate complicated virus capsids is believed to be a tough synthetic challenge. Here, we synthesize two large double-shell supramolecular cages by facile self-assembly of presynthesized metal-organic hexatopic terpyridine ligands with metal ions. Differing from the mixture of prisms formed from the inner tritopic ligand, the redesigned metal-organic hexatopic ligands bearing high geometric constraints that led to the exclusive formation of discrete double-shell structures. These two unique nested cages are composed of inner cubes (5.1 nm) and outer huge truncated cubes (12.0 and 13.2 nm) with six large bowl-shape subcages distributed on six faces. The results with molecular weights of 75 232 and 77 667 Da were among the largest synthetic cage-in-cage supramolecules reported to date. The composition, size and shape were unambiguously characterized by a combination of ¹H NMR, DOSY, ESI-MS, TWIM-MS, TEM, AFM, and SAXS. This work provides an interesting model for functional recognition, delivery, and detection of various guest molecules in the field of supramolecular materials.

Towards Macroscopically Anisotropic Functionality: Oriented Metallo-supramolecular Polymeric Materials Induced by Magnetic Fields

Based on the predesigned self-selective complexation, metallo-supramolecular P3HT-b-PEO diblock copolymers with varying block ratios were synthesized, and their oriented polymer films generated during solvent evaporation in a 9 T magnetic field were investigated. An anisotropic, ordered layer structure was achieved using [P3HT₂₀ -Zn-PEO₁₀₇ ] and carefully characterized by polarized optical microscopy (POM), AFM, polarized UV/Vis spectroscopy, and GI-SAXS/WAXS. The PEO-removed [P3HT₂₀ -Zn-PEO₁₀₇ ] film was obtained after decomplexation with TEA-EDTA under mild conditions, and the selective removal of PEO domains was evidenced by UV/Vis and ATR-FTIR spectroscopy. Anisotropic photoconductivity of the magnetically aligned film was evaluated by flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements. The results indicated that the presence of insulating crystalline PEO segments diminished the photoconductivity along the P3HT backbone direction.

Synthesis of Terpyridine End-Modified Polystyrenes through ATRP for Facile Construction of Metallo-Supramolecular P3HT-b-PS Diblock Copolymers

Complementary complexation between 2,2':6',2″-terpyridine (tpy) and 6,6″-dianthracenyl-substituted tpy in the presence of Zn(II) ions provided an efficient strategy for construction of metallo-supramolecular diblock copolymers. To synthesize well-defined tpy-modified polystyrenes (PSs), an Fe(II) bis(tpy) complex bearing α-bromoester as a metallo-initiator was applied to atom transfer radical polymerization (ATRP) to avoid poisoning the Cu(I) catalyst. Subsequently, a series of tpy-functionalized PSs was obtained after the decomplexation of junction by tetrakis(triethylammonium) ethylenediaminetetraacetate (TEA-EDTA) under mild conditions. The metallo-supramolecular poly(3-hexylthiophene) (P3HT)-block-PS diblock copolymers were prepared by simply mixing the corresponding terminally tpy-modified homopolymers with Zn(II) ions, and further characterized by 1H NMR and diffusion ordered spectroscopy (DOSY) experiments. The approach using metallo-initiators for ATRP offers an opportunity to construct tpy-functionalized polymers with controllable molecular weights and low polydispersities. Through the spontaneous heteroleptic complexation, a variety of metallo-supramolecular diblock copolymers with tunable block ratios can be easily constructed.

Conformational Regulation of Multivalent Terpyridine Ligands for Self-Assembly of Heteroleptic Metallo-Supramolecules

A two-ligand system composed of the predesigned multivalent and complementary terpyridine-based ligands was exploited to construct heteroleptic metallo-supramolecules and to investigate the self-assembly mechanism. Molecular stellation of the trimeric hexagon [Cd₆L²₃] gave rise to the exclusive self-assembly of the star hexagon [Cd₁₈L¹₆L³₃] through complementary ligand pairing between the ditopic and octatopic tectons. To understand how the intermolecular heteroleptic complexation influenced the self-assembly pathway, the star hexagon was truncated into two triangular fragments: [Cd₁₂L¹₃L⁴₃] and [Cd₁₂L¹₃L⁵₃]. In the self-assembly of [Cd₁₂L¹₃L⁴₃], the conformational movements of hexatopic ligand L⁴ could be regulated by L¹ to promote the subsequent coordination event, which was the key step to the successful multicomponent self-assembly. In contrast, the formation of [Cd₁₂L¹₃L⁵₃] was hampered by the geometrically mismatched intermediates.

Terbium-fluorido cluster: an energy cage for photoluminescence

We report here that energy migration during luminescence can be extremely minimized by caging the fluorescent centers in a molecular cluster of [Tb6(μ3-F)8(piv)10(Hpiv)4DMF]·xDMF·yH2O 1. Experimental and theoretical simulations reveal that bonding terbium with fluoride is the key to reducing the non-radiative multi-phonon relaxation processes, which is disparate to the common hydroxy-based lanthanide clusters.

Tetraphenylethylene(TPE)-Containing Metal-Organic Nanobelt and Its Turn-on Fluorescence for Sulfide (S2-)

A metal-organic supramolecular nanobelt was synthesized by quantitative self-assembling terpyridine-functionized tetraphenylethylene (TPE) and Cd²⁺, which only showed a weak emission both in solution or aggregated state. Nevertheless, nanobelt complex could be transferred to a fluorescence turn-on sensor to S^2- by taking advantage of the structural transformation from nanobelt to its fluorescent ligand.

Multicomponent Metallo-Supramolecular Nanocapsules Assembled from Calix[4]resorcinarene-Based Terpyridine Ligands

Tetrafunctionalized calix[4]resorcinarene cavitands commonly serve as supramolecular scaffolds for construction of coordination-driven self-assembled capsules. However, due to the calix-like shape, the structural diversity of assemblies is mostly restricted to dimeric and hexameric capsules. Previously, we reported a spontaneous heteroleptic complexation strategy based on a pair of self-recognizable terpyridine-based ligands and Cd^II ions. Building on this complementary ligand pairing system, herein three types of nanocapsules, including a dimeric capsule, a Sierpiński triangular prism, and a cubic star, could be readily obtained through dynamic complexation reactions between a tetratopic cavitand-based ligand and various multitopic counterparts in the presence of Cd^II ions. The dimeric capsular assemblies display the spacer-length-dependent self-sorting behavior in a four-component system. Moreover, the precise multicomponent self-assembly of a Sierpiński triangular prism and a cubic star possessing three and six cavitand-based motifs, respectively, demonstrates that such self-assembly methodology is able to efficiently enhance architectural complexity for calix[4]resorcinarene-containing metallo-supramolecules.

Precise Self-Assembly of Molecular Four- and Six-Pointed Stars

A novel metal-organic ligand (MOL 2) has been prepared by linking two V-shaped bis-terpyridines with one X-shaped tetrakis-terpyridine through the stable <tpy-Ru²⁺-tpy> connectivity. The complexation between MOL 2, X-shaped tetrakis-terpyridine, and Zn²⁺ gave rise to a supramolecular C₆-symmetrical six-pointed star quantitatively. In addition, a mixture of MOL 2, K-shaped tetrakis-terpyridine, and Zn²⁺ afforded a C₂-symmetrical four-pointed star. These metallo-supramolecular architectures were adequately characterized by NMR, ESI-MS, TWIM-MS, and TEM analyses.

One-Pot Self-Assembly of Stellated Metallosupramolecules from Multivalent and Complementary Terpyridine-Based Ligands

A series of stellated metallosupramolecular architectures have been assembled through three-component integrative self-sorting. Building on the complementary ligand pairing, the initial attempts to synthesize the hexagram complex from a combination of X-shaped tetrakis- and V-shaped bis-terpyridine ligands, and Cd^II ions, resulted in an unprecedented mixture of stellated octanuclear and dodecanuclear metallocages, which were further isolated by column chromatography. To overcome the unexpected obstacle, the multivalent ligand design along with spontaneous heteroleptic complexation was applied to realization of the one-pot synthesis of the intricate topology. A centrally situated triangle served as a prop for quantitative formation of the six-pointed stellated complex. Notably, in the absence of the triangular prop, a four-pointed star was produced.

Chemical mimicry of viral capsid self-assembly via corannulene-based pentatopic tectons

Self-assembly of twelve pentatopic tectons, which have complementary edges or can be linked using either digonal or trigonal connectors, represents the optimal synthetic strategy to achieve spherical objects, such as chemical capsids. This process requires conditions that secure uninterrupted equilibria of binding and self-correction en route to the global energy minimum. Here we report the synthesis of a highly soluble, deca-heterosubstituted corannulene that bears five terpyridine ligands. Spontaneous self-assembly of twelve such tectons with 30 cadmium(II) cations produces a giant icosahedral capsid as a thermodynamically stable single product in high yield. Nuclear magnetic resonance (NMR) methods, mass spectrometry analyses, small-angle X-ray scattering, transmission electron microscopy, and atomic force microscopy indicate that this spherical capsid has an external diameter of nearly 6 nm and shell thickness of 1 nm, in agreement with molecular modeling. NMR and liquid chromatography evidences imply that chiral self-sorting complexation generates a racemic mixture of homochiral capsids.

The icosahedron, as the polyhedron closest in symmetry to the sphere, is one of the most compelling Platonic solids for chemists to construct. Here, the authors assemble a supramolecular icosahedron from twelve pentatopic corannulene-based tectons, a strategy that was proposed over a decade ago but only now synthetically realized.

Geometrically Complementary Self-Assembly of a Hexarhomboid Architecture from Two Ruthenium(II)-Organic Building Blocks

A shape-persistent metallosupramolecular multirhomboid that inlays a hexarhomboid polygon in a three-lobed flat structure was prepared by means of coordination-driven self-assembly. The key ligands were synthesized by a "reaction on complex" strategy that becomes accessible to troublesome metalloorganic ligand L3. The formation here consists of four different starting components and two metal ions. Complementarity of the shape and size drives molecular puzzling and results in the multicomponent, quantitative self-assembled construct.

Construction and interconversion of anion-coordination-based ('aniono') grids and double helicates modulated by counter-cations

‘Aniono’ double helicates and grids were constructed using PO₄^3– anions and a bis–tris(urea) ligand and interconverted by changing the counter-cation.

Supramolecular assembly of well-defined discrete architectures has been of great interest due to the tunable properties of these structures in functional materials and bio-mimicking. While metal-coordination-driven assembly has been extensively studied, anion-coordination-driven assembly (ACDA) is just emerging for constructing complex supramolecular structures. Herein two A_2nL_2n (A = anion, L = ligand; n = 1 or 2) ‘aniono’-supramolecular assemblies, i.e. double helicates and the first anion grid, have been constructed based on the coordination between phosphate (PO₄^3–) anion and a bis–tris(urea) ligand. Moreover, the aniono-grid and double helicate motifs can be readily interconverted under ambient conditions by simply changing the counter-cation. These results redefine the power and scope of ACDA, which may represent a new approach in the assembly of well-defined architectures in parallel with the metal coordination-driven assembly of metallo-supramolecules.

Molecular Lemniscates from Organic-Metal Terpyridine-Based Self-Assembly and Host-Guest Recognition

The intricate discrete supramolecular architectures via two or more noncovalent interactions are very attractive for chemists. In this paper, a series of homomeric metallo-supramolecular lemniscates were prepared in nearly quantitative yields by assembling either dialkylammonium salt- or benzo-21-crown-7 (B21C7)-containing terpyridyl metallo-organic ligands with Zn²⁺. Furthermore, the heteromeric analogue could be obtained through two ways: (1) the cooperative interaction of coordination-driven self-assembly and host-guest recognition and (2) the transformation from homodimers to heterodimers driven by host-guest interaction. These supramolecules were characterized by nuclear magnetic resonance (NMR), diffusion-ordered NMR spectroscopy, electrospray ionization mass spectrometry, and two-dimensional (2D) ion-mobility mass spectrometry.

Facile synthesis of multicomponent heterobimetallic metallomacrocycles through selective metal–ligand coordination

Through selective coordination, three heterobimetallic Zn^II–Pd^II/Pt^II metallomacrocycles have been constructed by either a stepwise or a one-pot self-assembly protocol.

Metallaoctahedron Derived from the Self-Assembly of Tetranuclear Metal-Organic Ligands

Construction of 3D terpyridine-based metallopolyhedra remains challenging because of the linear coordination geometry of ⟨tpy-M^II-tpy⟩ connectivity. A progressive strategy is made by assembling tetranuclear terpyridyl metal-organic ligands to afford a novel regular octahedron, whose structure was established by NMR, electrospray ionization mass spectrometry, traveling-wave ion-mobility mass spectrometry, atomic force microscopy, and transmission electron microscopy. This strategy provides an efficient method for the construction of 3D terpyridine-based metallopolyhedra.

Truncated Sierpiński Triangular Assembly from a Molecular Mortise-Tenon Joint

The amalgamation of different components into a giant and intricate structure that makes quantitative and spontaneous assembly through molecular design is indispensable but challenging. To construct novel metallo-supramolecular architectures, here we present an architectural design principle based on multicomponent self-assembly. Using a carefully designed hexatopic terpyridine-based metallo-organic ligand (MOL), [Ru₂T₂K], we report on the formation of supramolecular trapezoid Zn₅[Ru₂T₂K]V₂, hollow hexagon Zn₁₅[Ru₂T₂K]₃K₃, and giant star-shaped supramolecule Zn₁₈[Ru₂T₂K]₃[Ru₂X₂V]₃, all of which were assembled by one-pot, nearly quantitative assembly of [Ru₂T₂K] with the ditopic 60°-directed bisterpyridine V, tetrakisterpyridine K, and MOL [Ru₂X₂V], respectively. The complementary ligands were selected on the basis of the size- and shape-fit principles, actually similar to the mortise-tenon joint that aligns and locks the two complementary wood components. This strategy is expected to open the door to sophisticated designer supramolecules and nonbiological materials. The multivalent connections within the mutual ligands give rise to the formation of stable assemblies, which are unambiguously characterized by NMR, ESI-MS, TWIM-MS, and TEM analyses.

Rationally designed divalent caffeic amides inhibit amyloid-β fibrillization, induce fibril dissociation, and ameliorate cytotoxicity

One of the pathologic hallmarks in Alzheimer's disease (AD) is extracellular senile plaques composed of amyloid-β (Aβ) fibrils. Blocking Aβ self-assembly or disassembling Aβ aggregates by small molecules would be potential therapeutic strategies to treat AD. In this study, we synthesized a series of rationally designed divalent compounds and examined their effects on Aβ fibrillization. A divalent amide (2) derived from two molecules of caffeic acid with a propylenediamine linker of ∼5.0 Å in length, which is close to the distance of adjacent β sheets in Aβ fibrils, showed good potency to inhibit Aβ(1-42) fibrillization. Furthermore, compound 2 effectively dissociated the Aβ(1-42) preformed fibrils. The cytotoxicity induced by Aβ(1-42) aggregates in human neuroblastoma was reduced in the presence of 2, and feeding 2 to Aβ transgenic C. elegans rescued the paralysis phenotype. In addition, the binding and stoichiometry of 2 to Aβ(1-40) were demonstrated by using electrospray ionization-traveling wave ion mobility-mass spectrometry, while molecular dynamic simulation was conducted to gain structural insights into the Aβ(1-40)-2 complex.

Multicomponent Self-Assembly of Metallo-Supramolecular Macrocycles and Cages through Dynamic Heteroleptic Terpyridine Complexation

Spontaneous formation of the heteroleptic cadmium(II) bis(terpyridine) complex under ambient conditions can be achieved by a combination of 6,6''-di(2,6-dimethoxylphenyl)-substituted and unsubstituted terpyridine-based ligands. Building on this dynamic heteroleptic complexation, diverse metallo-supramolecular macrocycles and cages were readily assembled in quantitative yields from the predesigned multicomponent systems. The complementary ligation reinforced self-recognition to facilitate the shape-dependent self-sorting of a four-component dynamic library into two well-defined parallelograms. In addition, the subtle lability difference between homoleptic and heteroleptic complexes led to the site-selective Cd^II -Zn^II transmetalation in the Sierpiński triangle. Facile construction of a dodecanuclear tetrahedral metallocage was also realized by using two self-recognizable tritopic building blocks. The photophysical study of the metallo-supramolecules assembled from the d¹⁰ metal ions revealed intense ligand-based photoluminescence in solution. The self-assembly strategy described here provides an efficient methodology for building pre-programmable, sophisticated supramolecular architectures furnished with photoactivity.

Evaluation of a multiplex flow immunoassay versus conventional assays in detecting autoantibodies in systemic lupus erythematosus

INTRODUCTION

Conventional diagnostic assays are being replaced with automated multiplex assays, but their performance needs to be evaluated. We compared a multiplex flow immunoassay with conventional techniques in the detection of antinuclear antibodies (ANAs) and antibodies to specific extractable nuclear antigens (ENAs) in serum samples from patients with systemic lupus erythematosus.

METHODS

A total of 140 consecutive Chinese patients with systemic lupus erythematosus and 41 healthy controls were included. The automated BioPlex 2200 ANA Screen assay (Bio-Rad Laboratories, Hercules [CA], US) was compared with indirect immunofluorescence. In addition, use of BioPlex 2200 to detect anti-ENA antibodies was compared with in-house assays of countercurrent immunoelectrophoresis (CIEP), enzyme-linked immunosorbent assay (ELISA), and line blot.

RESULTS

The sensitivity and specificity of BioPlex in detecting ANAs (91.4% and 95.1%, respectively) were comparable to those of indirect immunofluorescence (90.7% and 85.4%, respectively). Overall, BioPlex achieved the best agreement with ELISA in detecting anti-ENA antibodies: agreement was >90% for most antibody types (κ=0.79-0.94). In contrast, agreement was poorest with CIEP, ranging from 85.6% (κ=0.33) for anti-Sm antibodies to 93.9% (κ=0.88) for anti-Ro antibodies. Overall, BioPlex and ELISA had the highest sensitivity, whereas CIEP had the highest specificity. In terms of disease association, anti-Sm detected by CIEP had the best positive predictive value and specificity for lupus nephritis.

CONCLUSIONS

In a local lupus cohort, BioPlex showed comparable sensitivity to indirect immunofluorescence in detecting ANAs and comparable performance to ELISA in detecting anti-ENA antibodies. However, CIEP was the best method in terms of disease specificity.

Kinetics and equilibrium adsorption study of selenium oxyanions onto Al/Si and Fe/Si coprecipitates

Inappropriate treatments for the effluents from semiconductor plants might cause the releases and wide distributions of selenium (Se) into the ecosystems. In this study, Al/Si and Fe/Si coprecipitates were selected as model adsorbents as they often formed during the wastewater coagulation process, and the removal efficiency of selenite (SeO₃) and selenate (SeO₄) onto the coprecipitates were systematically examined. The removal efficiency of SeO₃ and SeO₄ was highly related to surface properties of Al/Si and Fe/Si coprecipitates. The surface-attached Al shell of Al/Si coprecipitates shielded a portion of negative charges from the core SiO₂, resulting in a higher point of zero charge than that of Fe/Si coprecipitates. Thus, adsorption of SeO₃/SeO₄ was favorable on the Al/Si coprecipitates. Adsorptions of both SeO₃ and SeO₄ on Al/Si coprecipitates were exothermic reactions. On Fe/Si coprecipitates, while SeO₃ adsorption also showed the exothermic behavior, SeO₄ adsorption occurred as an endothermic reaction. The kinetic adsorption data of SeO₃/SeO₄ on Al/Si and Fe/Si coprecipitates were described well by the pseudo-second-order kinetic model. SeO₄ and SeO₃ adsorption on Fe/Si or Al/Si were greatly inhibited by the strong PO₄ ligand, whereas the weak ligand such as SO₄ only significantly affected SeO₄ adsorption. The weakest complex between SeO₄ and Al was implied by the essentially SeO₄ desorption as SeO₄/PO₄ molar ratios decreased from 0.5 to 0.2. These results were further confirmed by the less SeO₄ desorption (41%) from Fe/Si coprecipitates than that from Al/Si coprecipitates (78%) while PO₄ was added sequentially.

Synthesis and Characterization of Ferrocene Based Hemicages

We present a series of tripodal ligands L1-3, which fold into hemicages C1-3 by using coordination-driven dynamic combinational chemistry. The identities of these hemicages were characterized using ¹H NMR, ¹H-¹H COSY, DOSY, and ESI-TWIM-MS. Free rotation of the ferrocene structural units in the ligands affords an adaptable directionality, which is essential for the construction of these hemicages. Encapsulation of adamantane by C2 indicates the presence of a well-defined inner cavity as the binding pocket.

Comparison of Kaposi Sarcoma Risk in Human Immunodeficiency Virus-Positive Adults Across 5 Continents: A Multiregional Multicohort Study

BACKGROUND

We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America.

METHODS

We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs).

RESULTS

We included 208140 patients from 57 countries. Over a period of 1066572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts ≥700 cells/µL with those whose counts were <50 cells/µL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by ≥95% in other regions.

CONCLUSIONS

Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa.

Metallo-Organic Ligand Designing Road for Constructing the First-Generation Dendritic Metallotriangle

Three approaches have been carefully examined in order to develop a terpyridine-based dendritic metallotriangle: (1) direct self-assembly of two types of organic polyterpyridines with metal ions; (2) assembly of flexible metallo-organic ligands containing two uncomplexed free terpyridines with a possible 60°-V-shaped orientation; (3) assembly of functionalized metallotriangles possessing a fixed 60°-bent uncoordinated bisterpyridine. Only the third approach has successfully given rise to the desired first-generation dendritic metallotriangle. Structural characterization was accomplished by NMR, ESI-TWIM-MS, and AFM.