Supramolecular polymers from coronene multicarboxylates and multipyridiniums in water stabilized by ion-pair attraction and aromatic stacking

Coronene tatracarboxylate CTC and octacarboxylate COC have been utilized to interact with dipyridinium DP and tetrapyridinium TP to assemble new supramolecular polymers in water. It was revealed that CTC interacted with DP and TP in 1:2 and 1:1 stoichiometry, whereas the binding between COC and DP and TP occurred in 1:4 and 1:2 stoichiometry. For all complexations, DP and TP behaved as a uni- or siamesed tweezers to clamp CTC or COC driven by ion-pair attraction and hydrophobically driven stacking of the pyridinium and coronene units. Apparent association constants were determined to be 33400 (CTC/DP), 9400 (COC/DP), 151000 (CTC/TP), and 89000 (COC/TP) M^?1, respectively, for the single clamping binding motif of the four complexes. Dynamic light scattering and isothermal titration calorimetric experiments supported that the mixtures of CTC and COC with TP formed linear and cross-linked supramolecular polymers.     

Investigation of the retention mechanism of naphthol and benzenediol on calix[4]arene stationary phase based on quantum chemistry calculations

Calixarenes are macrocyclic oligomers having the shape of a conical vase. Their inner cavity can accommodate various guest molecules, i. e. form supramolecules. Thus, calixarenes can be employed to manipulate selectivity in separation sciences. The essential step of separation is the interaction between calixarene and analytes. Therefore, in the present work, the retention mechanisms of benzenediol and naphthol positional isomers on a calix[4]arene column were investigated. The optimized supramolecular structures showed that there exist hydrogen bonding and pi-pi interactions for benzenediol, and for naphthol the pi-pi interactions dominate. Thermodynamic results from quantum chemistry calculations using DFT-B3LYP/STO-3G** basis set were consistent with the retention behaviors of benzenediol and naphthol positional isomers on the calix[4]arene column. This work will provide theoretical support for the design of new calixarene stationary phases.     

Synthesis and Characterization of Intercluster Compounds Consisting of Various Gold Clusters and Differently Charged Keggin Anions

The crystal structures of five intercluster compounds consisting of gold clusters and Keggin anions have been determined by single‐crystal x‐ray diffraction: [Au₉(PPh₃)₈][PMo₁₂O₄₀] (P4/n, Z = 2, a = 24.0195(13), c = 13.6818(10) Å), [Au₉(PPh₃)₈][HSiMo₁₂O₄₀] (P4/n, Z = 2, a = 24.270(3), c = 13.752(2) Å), [Au₉(PPh₃)₈][H₃CoW₁₂O₄₀] (P4/n, Z = 2, a = 24.4776(16), c = 13.7759(13) Å), [Au₈(PPh₃)₈]₂[SiMo₁₂O₄₀] (Pbca, Z = 4, a = 36.269(4), b = 24.488(3), c = 38.612(4) Å) and (nBu₄N)[Au₉(Ptol₃)₈][SiMo₁₂O₄₀] (Cc, Z = 4, a = 24.832(5), b = 24.955(5), c = 40.096(8) Å, β = 106.744(3)°). In these compounds, the charges of the building blocks were varied. Altering the charge on the Keggin anion in combination with the [Au₉(PPh₃)₈]³⁺ cluster gave rise to isostructural compounds as the charge is compensated by protonation of the polyoxometalate anion. Varying the charge or the ligand type of the gold cluster led to compounds with a completely different packing principle.     

Enantioselective total syntheses of ropivacaine and its analogues

An alternative asymmetric synthesis of ropivacaine and analogues employing the ‘cation pool’ strategy and host/guest supramolecular co-catalysis approach is presented. In this study, chiral auxiliaries, several soft nucleophiles as well as one-pot conditions for anodic oxidation, followed by nucleophilic addition, have been applied.     

Supramolecular assemblies based on some new methyl-substituted cucurbit[5]urils through hydrogen bonding

Three supramolecular assemblies based on three new partial methyl-substituted cucurbit[5]urils, which are tetramethylcucurbit[5]uril (α,γ-TMeQ[5]), hexamethyl cucurbit[5]uril (α,β,δ-HMeQ[5]), Nonamethylcucurbit[5]uril (NMeQ[5]), were synthesized and structurally characterized by single-crystal X-ray diffractions. For the comparison with these new Q[5]s, crystal structure of an assembly constructing with normal Q[5] and K₂PtCl₆ was also reported. They are (α,γ-TMeQ[5])·15(H₂O) (1), (α,β,δ-HMeQ[5])·2Cl⁻·2(H₃O)⁺·7(H₂O) (2), (NMeQ[5])·14(H₂O) (3), (4). In the corresponding crystal structures, the molecular encapsulates included a water molecule and lidded water molecules at both of the portals were observed. Moreover, these molecular encapsulates are connected through hydrogen bonding and formed supramolecular chains or joined in pair.     

Synthesis, structure and luminescent property of a new hybrid solid based on Keggin anions and silver-organonitrogen fragments

A new hybrid solid, {Ag(phen)₂}₂{[Ag(phen)]₂[PMo₁₂O₄₀]} (phen=1,10-phenanthroline) 1, constructed from one-electron-reduced mono-supported α-Keggin polyanions and silver-phenanthroline fragments via either covalent bonds or supramolecular interactions, is described. In the structure of 1, mono-supported {Ag(phen)[PMo₁₂O₄₀]}³⁻ polyanions are connected by {Ag(phen)}⁺ linking fragments to form a hybrid chain structure with engrafted phen ligands. {Ag(phen)₂}⁺ counter-cations occur in pairs trapping in strong inter-chain π-π stacking to form a three-dimensional supramolecular framework. Luminescent investigation of the compound indicates that 1 displays fascinating orange luminescent property at ambient temperature.     

Synthesis, crystal structures, and luminescent properties of two types of lanthanide phosphonates

Hydrothermal reactions of different lanthanide(III) salts with an amino-diphosphonate ligand (H₄L=C₆H₅CH₂N(CH₂PO₃H₂)₂) led to two series of lanthanide phosphonates, namely, Ln(H₂L)(H₃L) (Ln=La, 1; Pr, 2; Nd, 3; Sm, 4; Eu, 5; Gd, 6; Tb, 7). Compounds 1-5 feature a one-dimensional (1D) chain structure in which dimers of two edge-sharing LnO₈ polyhedra are interconnected by bridging phosphonate groups, such 1D arrays are further interlinked via strong hydrogen bonds between non-coordinated phosphonate oxygen atoms into a two-dimensional (2D) layer with the phenyl groups of the ligands orientated toward the interlayer space. Compounds 6 and 7 also show a different 1D array in which the LnO₆ octahedra are bridged by phosphonate groups via corner-sharing, such chains are also further interlinked by hydrogen bonds into a 2D supramolecular layer. Compounds 5 and 7 emit red and green light with a lifetime of 2.1 and 3.7 ms, respectively.     

Host-guest Assembly Based on γ-Cyclodextrin-functionalized Multiwalled Carbon Nanotubes for Rutin Electrochemical Sensing

Here, we report multiwalled carbon nanotubes (MWCNTs) functionalized with γ-cyclodextrins (γCD) as a novel electrochemical strategy for Rutin determination, showing superior performance than β-cyclodextrins (βCD) modified MWCNTs, suggesting an adequate environment for host-guest interactions. Under optimized conditions, the sensor showed a linear range of 39–975 nmol L⁻¹ and a limit of detection of 7 nmol L⁻¹. When tested with quercetin, catechin, and caffeine, the platform presented high selectivity with an interference response <10 %. The method was employed to quantify Rutin in spiked pharmaceutical and herbal extracts, providing recovery of 93–98.4 %. Also, HPLC-PDA confirmed the method‘s accuracy.     

Highly Selective Transmembrane Transport of Exogenous Lithium Ions through Rationally Designed Supramolecular Channels

Lithium ions have been applied in the clinic in the treatment of psychiatric disorders. In this work, we report artificial supramolecular lithium channels composed of pore-containing small aromatic molecules. By adjusting the lumen size and coordination numbers, we found that one of the supramolecular channels developed shows unprecedented transmembrane transport of exogenous lithium ions with a Li⁺/Na⁺ selectivity ratio of 23.0, which is in the same level of that of natural Na⁺ channels. Furthermore, four coordination sites inside channels are found to be the basic requirement for ion transport function. Importantly, this artificial lithium channel displays very low transport of physiological Na⁺, K⁺, Mg²⁺, and Ca²⁺ ions. This highly selective Li⁺ channel may become an important tool for studying the physiological role of intracellular lithium ions, especially in the treatment of psychiatric disorders.     

Ultrasound-Directed Symmetry Breaking and Spin Filtering of Supramolecular Assemblies from only Achiral Building Blocks

Herein we describe the self-assembly of an achiral molecule into macroscopic helicity as well as the emergent chiral-selective spin-filtering effect. It was found that a benzene-1,3,5-tricarboxamide (BTA) motif with an aminopyridine group in each arm could coordinate with Ag^I and self-assemble into nanospheres. Upon sonication, symmetry breaking occurred and the nanospheres transferred into helical nanofibers with strong CD signals. Although the sign of the CD signals appeared randomly, it could be controlled by using the as-made chiral assemblies as a seed. Furthermore, it was found that the charge transport of the helical nanofibers was highly selective with a spin-polarization transport of up to 45 %, although the chiral nanofibers are composed exclusively from achiral building blocks. This work demonstrates symmetry breaking under sonication and the chiral-selective spin-filtering effect.