Photodriven nonoxidative coupling of CH4 (NOCM) is a potential alternative approach to clean hydrogen and hydrocarbon production. Herein, a Mott–Schottky photocatalyst for NOCM is fabricated by loading Pt nanoclusters on a Ga-doped hierarchical porous TiO2–SiO2 microarray with an anatase framework, which exhibits a CH4 conversion rate of 3.48 μmol g–1 h–1 with 90% selectivity toward C2H6. This activity is 13 times higher than those from microarrays without Pt and Ga. Moreover, a continuous H2 production (36 μmol g–1) with a high CH4 conversion rate of ∼28% can be achieved through a longtime irradiation (32 h). The influence of Ga on the chemical state of a surface oxygen vacancy (Vo) and deposited Pt is investigated through a combination of experimental analysis and first-principles density functional theory calculations. Ga substitutes for the five-coordinated Ti next to Vo, which tends to stabilize the single-electron trapped Vo and reduce the electron transfer from Vo to the adsorbed Pt, resulting in the formation of a higher amount of cationic Pt. The cationic Pt and electron-enriched metallic Pt form a cationic–anionic active pair, which is more efficient for the dissociation of C–H bonds. However, the presence of too much cationic Pt results in more C2+ product with a decrease in the CH4 conversion rate due to the reduced charge-carrier separation efficiency. This study provides deep insight into the effect of the doping/loading strategy on the photocatalytic NOCM reaction and is expected to shed substantial light on future structural design and modulation.

Gold recovery using environmentally benign chemistry is imperative from an environmental perspective. Here we report the spontaneous assembly of a one-dimensional supramolecular complex with an extended {[K(OH2)6][AuBr4](α-cyclodextrin)2}n chain superstructure formed during the rapid co-precipitation of α-cyclodextrin and KAuBr4 in water. This phase change is selective for this gold salt, even in the presence of other square-planar palladium and platinum complexes. From single-crystal X-ray analyses of six inclusion complexes between α-, β- and γ-cyclodextrins with KAuBr4 and KAuCl4, we hypothesize that a perfect match in molecular recognition between α-cyclodextrin and [AuBr4]− leads to a near-axial orientation of the ion with respect to the α-cyclodextrin channel, which facilitates a highly specific second-sphere coordination involving [AuBr4]− and [K(OH2)6]+ and drives the co-precipitation of the 1:2 adduct. This discovery heralds a green host–guest procedure for gold recovery from gold-bearing raw materials making use of α-cyclodextrin—an inexpensive and environmentally benign carbohydrate.

A monofunctionalised pillar[5]arene derivative carrying a viologen side chain which exhibits self-complexation in dilute dichloromethane solutions forms supramolecular daisy chain polymers and eventually organogels as its concentration is increased three-fold over the range from 0.1 to 100 mM.

All reagents were purchased from commercial suppliers (Aldrich or Fisher) and used without further purification. Cyclobis(paraquat-p-phenylene) hexafluorophosphate S1 (CBPQT•4PF 6), and compounds S1 S2 , 2 S3 , 3 S4 , as well as the [2]rotaxane R1•4PF 6 S5 were all prepared according to literature procedures. Thin layer chromatography (TLC) was performed on silica gel 60 F254 (E. Merck). Column chromatography was carried out on silica gel 60F (Merck 9385, 0.040-0.063 mm). UV/Vis spectra were recorded on a Varian 100-Bio UV-Vis spectrophotometer in MeCN at room temperature. Nuclear magnetic resonance (NMR) spectra were recorded on Bruker Avance 600 or Varian P-Inova 500 spectrometers, with working frequencies of 600 and 500 MHz for 1 H, and 150 and 125 MHz for 13 C nuclei, respectively. Chemical shifts are reported in ppm relative to the signals corresponding to the residual non-deuterated solvents (CDCl 3 : δ = 7.26 ppm, CD 3 CN: δ =1.94 ppm). High-resolution mass spectra were measured, either on an Applied Biosystems Voyager DE-PRO MALDI TOF mass spectrometer (HR-TOF), or on a Finnigan LCQ iontrap mass spectrometer (HR-ESI). Cyclic voltammetry (CV) experiments were carried out at room temperature in argon-purged solutions in MeCN with a Gamry Multipurpose instrument (Reference 600) interfaced to a PC. CV Experiments were performed using a glassy carbon working electrode (0.071 cm 2). The electrode surface was polished routinely with 0.05 μm alumina-water slurry on a felt surface immediately before use. The counter electrode was a Pt coil and the reference electrode was silver/silver chloride. The concentration of the sample and supporting electrolyte (tetrabutylammonium hexafluorophosphate or tetrabutylammonium chloride) were 1.0 × 10 −3 mol L −1 and 0.1 mol L −1 , respectively. For the visible light lamp, we employed a standard incandescent bulb (60 W) without taking any extra precautions to select for specific wavelengths. S3 2. Synthetic Procedures S2: Compound S1 (490 mg, 1 mmol), 2-isopropylphenol (150 mg, 1.1 mmol) and K 2 CO 3 (1.38 g, 10 mmol) were added to a round-bottomed flask (250 mL) containing dry DMF (50 mL). The reaction mixture was stirred at 80 °C for 8 h. After cooling to room temperature, the solution was poured into H 2 O (200 mL). The resulting mixture was extracted with EtOAc (3 x 20 mL) and the combined organic phases were washed three times with saturated aqueous NaCl solution (3 x 100 mL). After drying (MgSO 4), the solvent was removed in vacuo and the resulting residue was purified by column chromatography (SiO 2 : Hexanes / EtOAc 50:50) to afford the desired product S2 (354 mg, 78%) as a light-yellow oil. 1

Ruthenium(II) polypyridyl complexes have emerged both as promising probes of DNA structure and as anticancer agents because of their unique photophysical and cytotoxic properties. A key consideration in the administration of those therapeutic agents is the optimization of their chemical reactivities to allow facile attack on the target sites, yet avoid unwanted side effects. Here, we present a drug delivery platform technology, obtained by grafting the surface of mesoporous silica nanoparticles (MSNPs) with ruthenium(II) dipyridophenazine (dppz) complexes. This hybrid nanomaterial displays enhanced luminescent properties relative to that of the ruthenium(II) dppz complex in a homogeneous phase. Since the coordination between the ruthenium(II) complex and a monodentate ligand linked covalently to the nanoparticles can be cleaved under irradiation with visible light, the ruthenium complex can be released from the surface of the nanoparticles by selective substitution of this ligand with a water molecule. Indeed, the modified MSNPs undergo rapid cellular uptake, and after activation with light, the release of an aqua ruthenium(II) complex is observed. We have delivered, in combination, the ruthenium(II) complex and paclitaxel, loaded in the mesoporous structure, to breast cancer cells. This hybrid material represents a promising candidate as one of the so-called theranostic agents that possess both diagnostic and therapeutic functions.

No abstract

Incorporation of a dual-FRET dye pair into mesoporous silica nanoparticles yields sensitive and sensing-range tunable nanosensors with good reversibility that can be used for ratiometric pH measurements under a single-wavelength excitation.

A homologous series of [2]rotaxanes, in which cyclobis(paraquat-p-phenylene) (CBPQT(4+)) serves as the ring component, while the dumbbell components all contain single 4,4'-bipyridinium (BIPY(2+)) units centrally located in the midst of oligomethylene chains of varying lengths, have been synthesized by taking advantage of radical templation and copper-free azide-alkyne 1,3-dipolar cycloadditions in the formation of their stoppers. Cyclic voltammetry, UV/vis spectroscopy, and mass spectrometry reveal that the BIPY(•+) radical cations in this series of [2]rotaxanes are stabilized against oxidation, both electrochemically and by atmospheric oxygen. The enforced proximity between the BIPY(2+) units in the ring and dumbbell components gives rise to enhanced Coulombic repulsion, destabilizing the ground-state co-conformations of the fully oxidized forms of these [2]rotaxanes. The smallest [2]rotaxane, with only three methylene groups on each side of its dumbbell component, is found to exist under ambient conditions in a monoradical state, a situation which does not persist in acetonitrile solution, at least in the case of its longer analogues. (1)H NMR spectroscopy reveals that the activation energy barriers to the shuttling of the CBPQT(4+) rings over the BIPY(2+) units in the dumbbells increase linearly with increasing oligomethylene chain lengths across the series of [2]rotaxanes. These findings provide a new way of producing highly stabilized BIPY(•+) radical cations and open up more opportunities to use stable organic radicals as building blocks for the construction of paramagnetic materials and conductive molecular electronic devices.