Versatile Syntheses of Hemi‐Cryptophanes and a Metallo‐Cryptophane from a Hexa‐Functionalized C3v‐Symmetrical Tribenzotriquinacene (TBTQ) Derivative

A number of three‐fold C_3v‐symmetrical tribenzotriquinacene (TBTQ) cavitands were synthesized by a “metamorphosis‐to‐half” strategy, employing six‐fold etherification reactions between the hexakis(chloromethyl)‐TBTQ intermediate 2 a and various 5‐functionalized resorcinols. X‐ray structure analyses of single crystals of the cavitands revealed limited rotational flexibility of the resorcinol bridging units, which enables an apical, nearly co‐axial orientation of the three functional groups and, as a consequence, the construction of nanoscale cage‐like molecules via covalent or coordination bonding. On this basis, two TBTQ‐based hemicryptophanes were prepared from the TBTQ cavitands via covalent bond formation in good yields. A dumbbell‐shaped TBTQ‐based metallo‐cryptophane was also synthesized in 34 % yield by a solvothermal reaction between cadmium nitrate and two equivalents of the TBTQ‐cavitand triacid, as confirmed by single‐crystal X‐ray diffraction and MALDI‐ToF mass spectrometry.     

Designed Synthesis of a 1D Polymer in Twist‐Stacked Topology via Single‐Crystal‐to‐Single‐Crystal Polymerization

To synthesize a fully organic 1D polymer in a novel twist‐stacked topology, we designed a peptide monomer HC≡CCH₂‐NH‐Ile‐Leu‐N₃, which crystallizes with its molecules H‐bonded along a six‐fold screw axis. These H‐bonded columns pack parallelly such that molecules arrange head‐to‐tail, forming linear non‐covalent chains in planes perpendicular to the screw axis. The chains arrange parallelly to form molecular layers which twist‐stack along the screw axis. Crystals of this monomer, on heating, undergo single‐crystal‐to‐single‐crystal (SCSC) topochemical azide–alkyne cycloaddition (TAAC) polymerization to yield an exclusively 1,4‐triazole‐linked polymer in a twist‐stacked layered topology. This topologically defined polymer shows better mechanical strength and thermal stability than its unordered form, as evidenced by nanoindentation studies and thermogravimetric analysis, respectively. This work illustrates the scope of topochemical polymerizations for synthesizing polymers in pre‐decided topologies.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

Synthesis,Characterization and Photoluminescence of Lanthanide Metal‐organic Frameworks,Constructed from Triangular 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate Ligands

Eight isomorphous metal‐organic frameworks: [Ln₂(TATAB)₂(H₂O)(DMA)₆]·5H₂O (Ln = Sm ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ), Er ( 6 ), Tm ( 7 ), Yb ( 8 )); TATAB = 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate, DMA = N,N‐dimethylacetamide), were synthesized by the self‐assembly of lanthanide ions, TATAB, DMA and H₂O. Single‐crystal X‐ray crystallography reveals they are three dimensional frameworks with 2‐fold interpenetration. Solid‐state photoluminescence studies indicate ligand‐to‐metal energy transfer is more efficient for compounds 2 and 4 which exhibit intense characteristic lanthanide emissions at room temperature.     

A 2‐fold Interpenetrated Framework based on Tetranuclear Heterometallic Cluster: Synthesis,Structure and Magnetic Properties

A 2‐fold parallel interpenetrated polymer, ZnCo(OH)(pheno)(p‐BDC)_1.5·H₂O ( 1 ) (pheno = phenanthrene‐9,10‐dione; p‐BDC = 1,4‐benzenedicarboxylate) has been prepared by hydrothermal synthesis and structurally characterized by IR, elemental analysis, ICP and single crystal X‐ray diffraction. Complex 1 crystallizes in the orthorhombic space group Pbca and affords a three‐dimensional (3D) six‐connected α‐Po network. The magnetic behavior for 1 was studied in the temperature range of 1.8‐300 K.     

Kinetics of the ene reactions of 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione with β‐pinene and 2‐carene: Temperature,high pressure,and solvent effects

The data on temperature, solvent, and high hydrostatic pressure influence on the rate of the ene reactions of 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione ( 1 ) with 2‐carene ( 2 ), and β‐pinene ( 4 ) have been obtained. Ene reactions 1 + 2 and 1 + 4 have high heat effects: ∆H_r‐n ( 1 + 2 ) −158.4, ∆H_r‐n( 1 + 4 ) −159.2 kJ mol⁻¹, 25°C, 1,2‐dichloroethane. The comparison of the activation volume (∆V^≠( 1 + 2 ) −29.9 cm³ mol⁻¹, toluene; ∆V^≠( 1 + 4 ) −36.0 cm³ mol⁻¹, ethyl acetate) and reaction volume values (∆V_r‐n( 1 + 2 ) −24.0 cm³ mol⁻¹, toluene; ∆V_r‐n( 1 + 4 ) −30.4 cm³ mol⁻¹, ethyl acetate) reveals more compact cyclic transition states in comparison with the acyclic reaction products 3 and 5 . In the series of nine solvents, the reaction rate of 1+2 increases 260‐fold and 1+4 increases 200‐fold, respectively, but not due to the solvent polarity.     

(1S,3R,8S,9S,10R)‐2,2‐Dichloro‐9,10‐epoxy‐3,7,7,10‐tetramethyltricyclo[6.4.0.01,3]dodecane and (1S,3R,8S,10R)‐2,2‐dichloro‐3,7,7,10‐tetramethyltricyclo[6.4.0.01,3]dodecan‐9‐one

The stereochemistries of the title compounds, both C₁₆H₂₄Cl₂O, have been established by X‐ray diffraction. In both structures, the seven‐membered ring adopts the same conformation, whereas the six‐membered ring shows an envelope conformation in the epoxy­do­decane structure and a boat conformation in the dodecan‐9‐one structure.     

Synthesis,Characterizations, Magnetism and Thermal Degradation of a 2‐Fold Interpenetrated 3D Cobalt‐Organic Framework

A new coordination polymer, [Co₂(L)₂(4,4′‐bipy)]_n·3nH₂O ( 1 ) based on 5‐(3‐methyl‐5‐phenyl‐4H‐1,2,4‐triazol‐4‐yl)isophthalic acid (H₂ L ) and 4,4′‐bipyridine (4,4′‐bipy) has been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction, XRPD, IR, and elemental analysis. Temperature‐dependent magnetic susceptibility and thermal degradation for 1 were also studied. The asymmetric unit of compound 1 consists of two crystallographically independent Co(II) ion, two L ^2? ligand, one 4,4′‐bipy ligand, and three lattice water molecules. The 2D triangle networks were linked by the bridging 4,4′‐bipy ligand to give rise to a 2‐fold interpenetrated 3D architecture. The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II) cations and three L ^2? ligands. So we can define Co(II) ions as 4‐connected nodes and the L ^2? ligands as 3‐connected nodes. Thus, the 3D structure can be described as a 2‐fold parallel interpenetrated ins InS 3,4‐conn topology.     

A High‐Pressure Polymorph of Phosphorus Nitride Imide

Phosphorus nitride imide, PN(NH), is of great scientific importance because it is isosteric with silica (SiO₂). Accordingly, a varied structural diversity could be expected. However, only one polymorph of PN(NH) has been reported thus far. Herein, we report on the synthesis and structural investigation of the first high‐pressure polymorph of phosphorus nitride imide, β‐PN(NH); the compound has been synthesized using the multianvil technique. By adding catalytic amounts of NH₄Cl as a mineralizer, it became possible to grow single crystals of β‐PN(NH), which allowed the first complete structural elucidation of a highly condensed phosphorus nitride from single‐crystal X‐ray diffraction data. The structure was confirmed by FTIR and ³¹P and ¹H solid‐state NMR spectroscopy. We are confident that high‐pressure/high‐temperature reactions could lead to new polymorphs of PN(NH) containing five‐fold‐ or even six‐fold‐coordinated phosphorus atoms and thus rivalling or even surpassing the structural variety of SiO₂.     

(η5‐Cyclopentadienyl)[(1,2,3,4,4a,10a‐η)‐1‐methylthianthrene]iron(II) hexafluoridophosphate acetone 0.33‐solvate

The title complex salt, [Fe(C₅H₅)(C₁₃H₁₀S₂)]PF₆·0.33C₃H₆O, obtained from an acetone–diethyl ether–dichloromethane mixture at 280 (2) K, has three cationic molecules (A–C), three hexafluoridophosphate counter‐anions and one acetone solvent molecule in the asymmetric unit. Two of the three cations contain FeCp (Cp is cyclopentadienyl) inside the fold of the heterocycle. The dihedral angles between the planes of the external (complexed and uncomplexed) benzene rings in the thianthrene molecule are 146.5 (2)° for FeCp‐out‐of‐fold molecule A, and 139.0 (3) and 142.5 (2)° for the two FeCp‐in‐fold molecules B and C, respectively. The complexed Cp and benzene rings in each molecule are almost parallel, with a dihedral angle between the planes of 0.2 (5)° for molecule A, 2.8 (5)° for B, and 2.19 (4) and 6.86 (6)° for the disordered Cp ring in C.     

Silica‐Encapsulated Pt‐Sn Intermetallic Nanoparticles: A Robust Catalytic Platform for Parahydrogen‐Induced Polarization of Gases and Liquids

Recently, a facile method for the synthesis of size‐monodisperse Pt, Pt₃Sn, and PtSn intermetallic nanoparticles (iNPs) that are confined within a thermally robust mesoporous silica (mSiO₂) shell was introduced. These nanomaterials offer improved selectivity, activity, and stability for large‐scale catalytic applications. Here we present the first study of parahydrogen‐induced polarization NMR on these Pt‐Sn catalysts. A 3000‐fold increase in the pairwise selectivity, relative to the monometallic Pt, was observed using the PtSn@mSiO₂ catalyst. The results are explained by the elimination of the three‐fold Pt sites on the Pt(111) surface. Furthermore, Pt‐Sn iNPs are shown to be a robust catalytic platform for parahydrogen‐induced polarization for in vivo magnetic resonance imaging.     

Two Disparate 2‐fold Interpenetrating Frameworks Constructed from ZnII, 4,4′‐Dipyridyl Disulfide and Maleic/ Fumaric Acid

The reaction of Zn^II nitrate with maleic acid (H₂mal) / fumaric acid (H₂fum) and 4,4′‐dipyridyl disulfide (4‐pds) resulted under same conditions in two distinct interpenetrated compounds, namely [Zn(4‐dps)₂(H₂O)₂]·2Hmal ( 1 ) and [Zn(4‐dps)(fum)] ( 2 ). In 1 , Hmal anion adopts bridging mode based on hydrogen bonding, affording a 2‐fold parallel interpenetrated 3D→3D α‐Po net hydrogen‐bonded framework, in which 1D double‐stranded chains are formed, and then extended to a 3D supramolecular architecture combining second‐sphere hydrogen‐bonded interactions. For 2 , fum dianion takes on bis‐dentate bridging coordination fashion, furnishing a 2‐fold interpenetrated 2D→2D (4,4) layered coordination network, in which the tetrahedral Zn^II atoms are interlinked by 4‐dps and fum. Additionally, the compound 2 shows strong fluorescence in the solid state at room temperature.     

A self‐contrast approach to evaluate the inhibitory effect of chrysosplenetin,in the absence and presence of artemisinin,on the in vivo P‐glycoprotein‐mediated digoxin transport activity

In this study, we used a self‐contrast method, which excluded the individual difference, to evaluate the inhibitory effect of chrysosplentin (CHR) in the presence or absence of artemisinin (ART) on the P‐glycoprotein (P‐gp) transport activity. A sensitive and rapid UHPLC–MS/MS method was applied for quantification of digoxin, a P‐gp‐specific substrate, in rat plasma. A pharmacokinetic study was carried out: first after an oral administration of digoxin at a dose of 0.09 mg/kg (first period), followed by a 20‐day wash‐out, then after another administration of digoxin (second period). During the second period, test compounds were orally given three times per day for seven consecutive days. Results showed that the t_1/2 of digoxin in all the groups had no significant difference between the first and second periods. The AUC_0–24, C_max, t_max, and Cl_z/F of the negative control and ART alone groups showed no difference. However, the AUC_0–24 and C_max in the CHR alone, CHR–ART (1:2) and verapamil (positive control) groups showed 2.34‐, 3.04‐, 1.79‐, and 1.81‐, 1.99‐, 2.06‐fold increases along with 3.50‐, 3.84‐ and 4.76‐fold decreases for CL_z/F, respectively. The t_max in the CHR–ART (1:2) group increased 3.73‐fold. In conclusion, our self‐contrast study suggested that CHR, especially when combined with ART in a ratio of 1:2, inhibited P‐gp activity while ART alone has no effect. Copyright © 2016 John Wiley & Sons, Ltd.     

Control of Heterometallic Three‐Dimensional Macrocycles with Aromatic Stacks in Tunable Host Cavities

Using coinage metal (Cu(II), Ag(I)) hinges, two sets of heterometallic molecular capsules with analogous open‐ended cavities were prepared based on the half‐sandwich rhodium fragments. In the case of [Rh₄Cu₄] cages, up to six‐fold‐stacked host‐guest structures were formed by varying the cavity's dimensions. Moreover, the series of capsules were demonstrated to self‐fine‐tune to form multi‐heteroguest arrays via favourable donor‐acceptor π interactions and Ag‐π interactions, as evidenced from single‐crystal X‐ray analysis.     

Investigation of the Reaction of Gold(III) with 2‐[2‐(4‐Dimethylamino‐Phenyl)‐Vinyl]‐1,3,3‐Trimethyl‐3H‐Indolium. Application for Determination of Gold

A new, simple, rapid, sensitive, efficient and low‐cost spectrophotometric procedure for the determination of gold was developed. The method is based on the reaction of [AuCl₄]^? with 2‐[2‐(4‐dimethylaminophenyl)‐vinyl]‐1,3,3‐trimethyl‐3H‐indolium reagent to form a colored ion associate extractable by various organic solvents. The molar absorptivity of the ion associates is in the range (5.7–9.2) × 10⁴ L mol^?1 cm^?1 depending on the extractant. Butyl acetate was chosen as the extractant. The optimum reaction conditions were established: pH 2–4, concentration of the dye reagent (0.8–1.5) × 10^?4 mol L^?1. The determination of gold is not hindered even by a 1000‐fold concentration of Ni and Co; a 500‐fold concentration of Pb and Zn; a 100‐fold concentration of Bi, Cu, Cd, Pt, Rh and Ru; or a 20‐fold concentration of Ag. The established method was applied to the determination of gold in model samples and enriched polymetallic ores.     

Production of Hydrogen by Glycerol Photoreforming Using Binary Nitrogen–Metal‐Promoted N‐M‐TiO2 Photocatalysts

The need for renewable energy focuses attention on hydrogen obtained by using sustainable and green methods. The sustainable compound glycerol can be used for hydrogen production by heterogeneous photocatalysis. A novel approach involves the promotion of the TiO₂ photocatalyst with a binary combination of nitrogen and transition metal. We report the synthesis and spectroscopic characterization of the new N‐M‐TiO₂ photocatalysts (M=none, Cr, Co, Ni, Cu), and the photocatalytic reforming of glycerol to hydrogen under ambient conditions and near‐UV or visible light versus benchmark P25 TiO₂. In units of activity μmol m^?2 h^?1, N‐Ni‐TiO₂ is five‐fold more active than P25, and N‐Cu‐TiO₂ is 44‐fold more active. The photocatalytic activity of N‐M‐TiO₂ increases from Cr to Co and Ni, whereas the photoluminescence decreases; the change in activity is due to the modulation of charge recombination.     

Tetraethylene Glycol Tethered Heteronuclear Bis‐isatin Derivatives: Design,Synthesis, and In Vitro Anti‐mycobacterial Activities

A series of novel tetraethylene glycol tethered heteronuclear bis‐isatin derivatives 7a – l were designed, synthesized, and evaluated for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant TB (MDR‐TB) as well as cytotoxicity in VERO cell line. All hybrids exhibited potential anti‐mycobacterial activities against MTB H37Rv and MDR‐TB, and acceptable cytotoxicity. Among them, the heteronuclear bis‐isatin 7l [minimum inhibitory concentration (MIC): 16 and 16 μg/mL] was found to be most active against MTB H37Rv and MDR‐TB strains, which was 2‐fold and >8‐fold, respectively, more potent than were the first‐line anti‐tubercular agents rifampicin (MIC: 32 μg/mL) and isoniazid (MIC: >128 μg/mL) against MDR‐TB, also demonstrated acceptable cytotoxicity profile (CC₅₀: 62.5 μg/mL), could act as a starting point for further optimization.     

A Photoswitchable Agonist for the Histamine H3 Receptor,a Prototypic Family A G‐Protein‐Coupled Receptor

Spatiotemporal control over biochemical signaling processes involving G protein‐coupled receptors (GPCRs) is highly desired for dissecting their complex intracellular signaling. We developed sixteen photoswitchable ligands for the human histamine H₃ receptor (hH₃R). Upon illumination, key compound 65 decreases its affinity for the hH₃R by 8.5‐fold and its potency in hH₃R‐mediated G_i protein activation by over 20‐fold, with the trans and cis isomer both acting as full agonist. In real‐time two‐electrode voltage clamp experiments in Xenopus oocytes, 65 shows rapid light‐induced modulation of hH₃R activity. Ligand 65 shows good binding selectivity amongst the histamine receptor subfamily and has good photolytic stability. In all, 65 (VUF15000) is the first photoswitchable GPCR agonist confirmed to be modulated through its affinity and potency upon photoswitching while maintaining its intrinsic activity, rendering it a new chemical biology tool for spatiotemporal control of GPCR activation.     

Anion‐Responsive Tunable Bulk‐Phase Homochirality and Luminescence of a Cationic Framework

Reaction of a linear bi‐chelating N‐donor achiral ligand with Zn^II afforded a homochiral cationic framework with six‐fold one‐dimensional helical chains. The compound showed selective anion exchange behavior with interesting anion‐responsive tunable bulk‐phase homochirality. The cationic framework also presented anion‐driven variable luminescence and sorption behavior.     

A Red‐Light‐Activated Ruthenium‐Caged NAMPT Inhibitor Remains Phototoxic in Hypoxic Cancer Cells

We describe two water‐soluble ruthenium complexes, [ 1 ]Cl₂ and [ 2 ]Cl₂, that photodissociate to release a cytotoxic nicotinamide phosphoribosyltransferase (NAMPT) inhibitor with a low dose (21 J cm⁻²) of red light in an oxygen‐independent manner. Using a specific NAMPT activity assay, up to an 18‐fold increase in inhibition potency was measured upon red‐light activation of [ 2 ]Cl₂, while [ 1 ]Cl₂ was thermally unstable. For the first time, the dark and red‐light‐induced cytotoxicity of these photocaged compounds could be tested under hypoxia (1 % O₂). In skin (A431) and lung (A549) cancer cells, a 3‐ to 4‐fold increase in cytotoxicity was found upon red‐light irradiation for [ 2 ]Cl₂, whether the cells were cultured and irradiated with 1 % or 21 % O₂. These results demonstrate the potential of photoactivated chemotherapy for hypoxic cancer cells, in which classical photodynamic therapy, which relies on oxygen activation, is poorly efficient.