Fluorenonophane chlorobenzene solvate: molecular and crystal structures

The title compound, 19 H,79 H-3,5,9,11-tetraoxa-1,7(2,7)-difluorena-4,10(1,3)-dibenzenacyclododecaphane-19,79-dione (fluorenonophane), exists as a solvate with chlorobenzene, C42H28O6·C6H5Cl. The fluorenonophane contains two fluorenone fragments linked by two m-substituted benzene fragments. Some decrease in its macrocyclic cavity leads to a stacking interaction between the tricyclic fluorenone fragments. In the crystal, the fluorenonophane and chlorobenzene molecules are linked by weak C—H...π(ring) interactions and C—H...Cl hydrogen bonds. The Cl atom of chlorobenzene does not form a halogen bond. A Hirshfeld surface analysis and two-dimensional fingerprint plots were used to analyse the intermolecular contacts found in the crystal structure.

Size-control in the synthesis of oxo-bridged phosphazane macrocycles via a modular addition approach

Inorganic macrocycles remain largely underdeveloped compared with their organic counterparts due to the challenges involved in their synthesis. Among them, cyclodiphosphazane macrocycles have shown to be promising candidates for supramolecular chemistry applications due to their ability to encapsulate small molecules or ions within their cavities. However, further developments have been handicapped by the lack of synthetic routes to high-order cyclodiphosphazane macrocycles. Moreover, current approaches allow little control over the size of the macrocycles formed. Here we report the synthesis of high-order oxygen-bridged phosphazane macrocycles via a “3 + n cyclisation” (n = 1 and 3). Using this method, an all-PIII high-order hexameric cyclodiphosphazane macrocycle was isolated, displaying a larger macrocyclic cavity than comparable organic crown-ethers. Our approach demonstrates that increasing building block complexity enables precise control over macrocycle size, which will not only generate future developments in both the phosphazane and main group chemistry but also in the fields of supramolecular chemistry.

Selective Binding of Cyclodextrins with Leflunomide and Its Pharmacologically Active Metabolite Teriflunomide

The selectivity of encapsulation of leflunomide and teriflunomide by native α-, β- and γ-cyclodextrins was investigated through 1H NMR and molecular modeling. Thermodynamic analysis revealed the main driving forces involved in the binding. For α-cyclodextrin, the partial encapsulation was obtained while deep penetration was characterized for the other two cyclodextrins, where the remaining polar fragment of the molecule is located outside the macrocyclic cavity. The interactions via hydrogen bonding are responsible for high negative enthalpy and entropy changes accompanying the complexation of cyclodextrins with teriflunomide. These results were in agreement with the molecular modeling calculations, which provide a clearer picture of the involved interactions at the atomic level.

A Facile Modular Addition Approach to Size Control in the Synthesis of Oxo Bridged Phosphazane Macrocycles

Inorganic macrocycles remain largely underdeveloped compared with their organic counterparts due to the challenges involved in their synthesis. Among them, cyclodiphosphazane macrocycles have shown to be promising candidates for supramolecular chemistry applications. However, further developments have been handicapped by the lack of synthetic routes to high-order cyclodiphosphazane macrocycles. Here we report the synthesis of high-order oxygen-bridged phosphazane macrocycles via a “3+n” (n= 1 and 3) condensation reaction synthetic strategy using novel trimeric building blocks. Using this method, the first-ever all-PIII high-order hexameric cyclodiphosphazane macrocycle was isolated, displaying a larger macrocyclic cavity than comparable organic crown-ether counterparts. Our approach demonstrates that increasing building block complexity enables unprecedented rational control over macrocycle size.

A Facile Modular Addition Approach to Size Control in the Synthesis of Oxo Bridged Phosphazane Macrocycles

Inorganic macrocycles remain largely underdeveloped compared with their organic counterparts due to the challenges involved in their synthesis. Among them, cyclodiphosphazane macrocycles have shown to be promising candidates for supramolecular chemistry applications. However, further developments have been handicapped by the lack of synthetic routes to high-order cyclodiphosphazane macrocycles. Here we report the synthesis of high-order oxygen-bridged phosphazane macrocycles via a “3+n” (n= 1 and 3) condensation reaction synthetic strategy using novel trimeric building blocks. Using this method, the first-ever all-PIII high-order hexameric cyclodiphosphazane macrocycle was isolated, displaying a larger macrocyclic cavity than comparable organic crown-ether counterparts. Our approach demonstrates that increasing building block complexity enables unprecedented rational control over macrocycle size.

pH-Dependent Electrochemically Catalyzed Oxygen Reduction Behaviors of o-Substituted Co (III) Corroles Research Data.pdf

<p>Supporting Information for article. </p> <p>Earth-abundant first row transition metal corrole complexes have played an important role in fundamental research due to their unique molecular structures and attractive properties. In comparison to porphyrins, corroles have three inner N-H protons and are ring-contracted with a smaller macrocyclic cavity. First row transition metal corroles have been widely used as effective electrochemical catalysts for small molecule activations, such as hydrogen evolution, oxygen reduction/evolution and CO2 reduction reactions (HERs, ORRs/OERs and CO2 RRs) through homogenous and/or heterogenous prodecures. Several strategies have been used to modulate the catalytic efficiency of synthetic metallocorroles.</p>

pH-Dependent Electrochemically Catalyzed Oxygen Reduction Behaviors of o-Substituted Co (III) Corroles Research Data.pdf

<p>Supporting Information for article. </p> <p>Earth-abundant first row transition metal corrole complexes have played an important role in fundamental research due to their unique molecular structures and attractive properties. In comparison to porphyrins, corroles have three inner N-H protons and are ring-contracted with a smaller macrocyclic cavity. First row transition metal corroles have been widely used as effective electrochemical catalysts for small molecule activations, such as hydrogen evolution, oxygen reduction/evolution and CO2 reduction reactions (HERs, ORRs/OERs and CO2 RRs) through homogenous and/or heterogenous prodecures. Several strategies have been used to modulate the catalytic efficiency of synthetic metallocorroles.</p>

Total oxidation of decahydroxypillar[5]arene with copper(II) and iron(III) nitrates

Pillar[n]arenes are suitable synthetic platforms for synthesis of functionalized p-cyclophanes, versatile building blocks for creating supramolecular polymers and (pseudo)rotaxanes. The presence of hydroquinone fragments in unsubstituted pillar[n]arene derivatives opens wide opportunities for their application in electrochemical sensors and for their use as reducing agents for synthesis of hybrid materials. Macrocyclic cavity plays the key role in molecular recognition, supramolecular self-assembly of pillararenes, and therefore possibility of switching electron donor properties of aromatic moieties, forming macrocyclic cavity presents specific interest. Synthesis of pillar[n]quinones is non-trivial goal, usually, it requires expensive reagents (сerium(IV) ammonium nitrate). As an oxidized compound alkoxy-derivatives of pillararenes are used. While possibility of red-ox transitions of decahydroxypillar[5]arene are well known, to the date in literature there are no examples of total oxidation of decahydroxypillar[5]arene. We have studied interaction of decahydroxy-pillar[5]arene with a row of inorganic oxidants: catalytic oxidation with air oxygen in presence of copper(II) and iron(III) nitrates, and oxidation with ammonium persulfate. In order to find the optimal conditions for oxidation of pillar[5]arene the series of solvents were tried (proton donor alcohols and acetic acid, proton acceptor dimethylformamide and dimethylsulfoxide). It was established that using glacial acetic acid as a solvent with ultrasonication leads to total oxidation of pillar[5]arene to pillar[5]quinone. This fact is explained by strong proton-donor properties of glacial acetic acid, to prevent formation of insoluble quinhydrone complexes of pillar[5]arene oxidation products. Using ammonium persulfate does not lead to the product of total oxidation.

Solution-mediated and single-crystal to single-crystal transformations of cucurbit[6]uril host–guest complexes with dopamine

The structural transformations of cucurbit[6]uril–dopamine complexes are associated with loss of water molecules either from the macrocyclic cavity or from the crystal lattice.

Molecular recognition using tetralactam macrocycles with parallel aromatic sidewalls

This review summarizes the supramolecular properties of tetralactam macrocycles that have parallel aromatic sidewalls and four NH residues directed into the macrocyclic cavity. These macrocycles are versatile hosts for a large number of different guest structures in water and organic solvents, and they are well-suited for a range of supramolecular applications. The macrocyclic cavity contains a mixture of polar functional groups and non-polar surfaces which is reminiscent of the amphiphilic binding pockets within many proteins. In water, the aromatic surfaces in the tetralactam cavity drive high affinity due the hydrophobic effect and the NH groups provide secondary interactions that induce binding selectivity. In organic solvents, the supramolecular factors are reversed; the polar NH groups drive high affinity and the aromatic surfaces provide the secondary interactions. In addition to an amphiphilic cavity, macrocyclic tetralactams exhibit conformational flexibility, and the combination of properties enables them to be effective hosts for a wide range of guest molecules including organic biscarbonyl derivatives, near-infrared dyes, acenes, precious metal halide complexes, trimethylammonium ion-pairs, and saccharides.