Crystal structure of -xylene@silicalite-1.

The crystal structure of a highly loaded complex of silicalite-1 (SL-1) with eight mol-ecules of -xylene per unit cell has been solved by single-crystal X-ray diffraction. In the crystal, four symmetrical SiO·2CH subunits per unit cell are observed. The -xylene mol-ecules sit at two different positions within the SL-1 channels.

The pH Response of a Peptoid Oligomer.

Polypeptoids are -substituted glycine polymers, which differ from peptides in the placement of the side chain on the amide nitrogen rather than the C carbon. A peptoid with a chiral side chain containing both an aromatic group and carboxylic acid has a structure that responds to pH changes. All-atom molecular dynamics simulations using a force field specifically tuned for peptoids were carried out with an advanced sampling method for the peptoid ()--(1-carboxy-2-phenylethyl)glycine in the high and low pH limits.

Dramatically Enhanced Reactivity of Fullerenes and Tetrazine towards the Inverse-Electron-Demand Diels-Alder Reaction inside a Porous Porphyrinic Cage.

Inverse-electron-demand Diels-Alder reaction (IEDDA) between fullerenes and 1,2,4,5-tetrazine generally requires harsh conditions and long reaction times due to their strong electron-accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C /C )-tetrazine reaction inside a porous Zn-porphyrinic cage (Zn-PB) under sustainable conditions by installing a tetrazine-based axle (LA) via metal-ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene-tetrazine adducts.

One-pot Synthesis of a Truncated Cone-shaped Porphyrin Macrocycle and Its Self-assembly into Permanent Porous Material.

Here, we report the synthesis of a truncated cone-shaped triangular porphyrinic macrocycle, P L , via a single step imine condensation of a cis-diaminophenylporphyrin and a bent dialdehyde-based linker as building units. X-ray diffraction analysis reveals that the truncated cone-shaped P L molecules are stacked on top of each other by π⋯π and CH⋯π interactions, to form 1.7 nm wide hollow columns in the solid state.

Programmable Synthesis of Silver Wheels.

The synthesis of sandwich-shaped multinuclear silver complexes with planar penta- and tetranuclear wheel-shaped silver units and a central anion, [Ag()(A)](OTf), , = 4 or 5 and A = OH or F or Cl, is reported, along with complete spectroscopic and structural characterization. An NMR mechanistic study reveals that silver complexes were formed in the following order: → → → . The central hydroxides in and exhibit exotic physical properties due to the confined environment inside the complex.

Transient Self-assembly Processes Operated by Gaseous Fuels under Out-of-Equilibrium Conditions.

Herein we report transient out-of-equilibrium self-assembly of molecules operated by gaseous fuel mixtures. The combination of an active gaseous chemical fuel and an inert gas or compressed air, which assists the degassing of the gaseous fuel from the solution, drives the transient self-assembly process. The gaseous nature of the fuel as well as the exhaust helps in their easy removal and thereby prevents their accumulation within the system and helps in maintaining the efficiency of the transient self-assembly process.

Supramolecular Fullerene Tetramers Concocted with Porphyrin Boxes Enable Efficient Charge Separation and Delocalization.

Herein, we report a novel porphyrin/fullerene supramolecular cocrystal using a shape-persistent zinc-metalated porphyrin box (Zn-PB) and C/C. An unprecedented arrangement of a tightly packed square-planar core of four C or C surrounded by six cube-shaped Zn-PBs was observed. This unique packing promotes strong charge transfer (CT) interactions between the two components in the ground state and formation of charge-separated states with very long lifetimes in the excited state and enables unusually high photoconductivity.

Hierarchical Self-Assembly of Poly-Pseudorotaxanes into Artificial Microtubules.

Hierarchical self-assembly of building blocks over multiple length scales is ubiquitous in living organisms. Microtubules are one of the principal cellular components formed by hierarchical self-assembly of nanometer-sized tubulin heterodimers into protofilaments, which then associate to form micron-length-scale, multi-stranded tubes. This peculiar biological process is now mimicked with a fully synthetic molecule, which forms a 1:1 host-guest complex with cucurbit[7]uril as a globular building block, and then polymerizes into linear poly-pseudorotaxanes that associate laterally with each other in a self-shape-complementary manner to form a tubular structure with a length over tens of micrometers.

Fuel-Driven Transient Crystallization of a Cucurbit[8]uril-Based Host-Guest Complex.

Transient self-assembling systems often suffer from accumulation of chemical wastes that interfere with the formation of pristine self-assembled products in subsequent cycles. Herein, we report the transient crystallization of a cucurbit[8]uril-based host-guest complex, preventing the accumulation of chemical wastes. Base-catalyzed thermal decarboxylation of trichloroacetic acid that chemically fuels the crystallization process dissolves the crystals, and produces volatile chemical wastes that are spontaneously removed from the solution.

Rational Design and Construction of Hierarchical Superstructures Using Shape-Persistent Organic Cages: Porphyrin Box-Based Metallosupramolecular Assemblies.

We report a new approach to building hierarchical superstructures using a shape-persistent porous organic cage, which acts as a premade secondary building unit, and coordination chemistry. To illustrate the principle, a zinc-metalated porphyrin box (Zn-PB), a corner-truncated cubic porous cage, was connected by suitable dipyridyl terminated bridging ligands to construct PB-based hierarchical superstructures (PSSs). The PSSs were stabilized not only by the coordination bonds between Zn ions and bipyridyl-terminated ligands but also by π-π interactions between the corners of the Zn-PB units.

Hollowing out MOFs: hierarchical micro- and mesoporous MOFs with tailorable porosity selective acid etching.

We report a new strategy for the synthesis of robust hierarchical micro- and mesoporous MOFs from water stable MOFs a selective acid etching process. The process is controlled by the size-selective diffusion of acid molecules through the MOF windows. This method enables the fine-tuning of the porosity of hierarchical MOFs, allowing for the generation of well-defined mesopores with high mesopore volume.

Iodide-Selective Synthetic Ion Channels Based on Shape-Persistent Organic Cages.

We report here a synthetic ion channel developed from a shape-persistent porphyrin-based covalent organic cage. The cage was synthesized by employing a synthetically economical dynamic covalent chemistry (DCC) approach. The organic cage selectively transports biologically relevant iodide ions over other inorganic anions by a dehydration-driven, channel mechanism as evidenced by vesicle-based fluorescence assays and planar lipid bilayer-based single channel recordings.

High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages.

Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π-π stacking between the H3BTB moieties.

CO2 capture from humid flue gases and humid atmosphere using a microporous coppersilicate.

Capturing CO2 from humid flue gases and atmosphere with porous materials remains costly because prior dehydration of the gases is required. A large number of microporous materials with physical adsorption capacity have been developed as CO2-capturing materials. However, most of them suffer from CO2 sorption capacity reduction or structure decomposition that is caused by co-adsorbed H2O when exposed to humid flue gases and atmosphere.

Manual assembly of nanocrystals for enhanced photoelectrochemical efficiency of hematite film.

To improve the optoelectronic properties of hematite film as a photoanode, hematite film was orientated on the (012) plane by the secondary growth of organized microcrystals. The resultant film showed promising photoelectrochemical effects compared with a randomly oriented one, with a maximum photocurrent of 0.8 mA cm(-2) at 1.

Effect of metal doping, doped structure, and annealing under argon on the properties of 30 nm thick ultrathin hematite photoanodes.

The doping of the whole hematite layer with W (9.4%) and the additional doping of the bottom half of the W-doped hematite layer with Sn (8.6%), and the subsequent annealing under argon at 600 °C give rise to large increases in the Fe(2+) concentration (by >∼200 times), carrier density (Cd, by ∼48 times) and current density (i(d), by ∼8 times at 1.

A novel vanadosilicate with hexadeca-coordinated Cs(+) ions as a highly effective Cs(+) remover.

The effective removal of (137) Cs(+)  ions from contaminated groundwater and seawater and from radioactive nuclear waste solutions is crucial for public health and for the continuous operation of nuclear power plants. Various (137) Cs(+)  removers have been developed, but more effective (137) Cs(+)  removers are still needed. A novel microporous vanadosilicate with mixed-valence vanadium (V(4+) and V(5+) ) ions is now reported, which shows an excellent ability for Cs(+)  capture and immobilization from groundwater, seawater, and nuclear waste solutions.

Calix[n]imidazolium as a new class of positively charged homo-calix compounds.

Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium.

Fluorogenic sensing of CH3CO2- and H2PO4- by ditopic receptor through conformational change.

Cyclo-bis-(urea-3,6-dichlorocarbazole) (1) forms a 1 : 2 complex with CH(3)CO(2)(-) and H(2)PO(4)(-) through hydrogen bonding with the two urea moieties, resulting in fluorescence enhancement via a combined photoinduced electron transfer (PET) and energy transfer mechanism. The binding mechanism involves a conformational change of the two urea receptors to a trans orientation after binding of the first anion, which facilitates the second interaction.

Thermally stable intermolecular proton bonds in polyaromatic aldehyde crystals.

We have synthesized self-assembled red-colored proton complexes of the aldehyde derivatives of polyaromatic hydrocarbon with strong intermolecular hydrogen bonding. These intermolecularly proton-bonded polyaromatic aldehydes formed as 1-pyrenecarbaldehyde (Py-CHO) reacted with HAuCl(4) to produce [(Py-CHO)(2)H][AuCl(4)] under dry conditions. The formation of [(Py-CHO)(2)H][AuCl(4)] was confirmed by single-crystal structure determination and IR spectral analysis at various temperatures.

Photoactivated racemization catalyst for dynamic kinetic resolution of secondary alcohols.

Household fluorescent light activates a diruthenium complex to generate catalytic species highly active for the racemization of secondary alcohols under ambient conditions. This catalyst system is applicable for the chemoenzymatic dynamic kinetic resolution of racemic alcohols to give optically pure acetates under mild conditions.

Water-dispersible magnetite-reduced graphene oxide composites for arsenic removal.

Magnetite-graphene hybrids have been synthesized via a chemical reaction with a magnetite particle size of approximately 10 nm. The composites are superparamagnetic at room temperature and can be separated by an external magnetic field. As compared to bare magnetite particles, the hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem.

Self-assembled thermally highly stable 1-dimensional proton arrays.

From a red proton complex of aldehyde derivatives of polyaromatic hydrocarbon with strong intermolecular hydrogen bonding, which are novel examples of intermolecular proton-bonded aldehydes of polyaromatic hydrocarbons, we find one-dimensional proton arrangement. The complex formed as 9-antraldehyde (Ant-CHO) reacts with HAuCl(4) to form [(Ant-CHO)(2)H](+)[AuCl(4)](-) under dry condition, which are confirmed by single-crystal structure determination and infrared spectra analysis at varying temperatures. Since the compounds of distinctively hydrophobic nature are soluble only in limited organic polar solvents, the strong hydrogen bonds are clearly observed from both the electron density of X-ray analysis and the characteristic signature of the IR frequency.