Oksana Danylyuk

Conformational extremes in the supramolecular assemblies of para-sulfonato-calix[8]arene

Two complex solid state structures of para-sulfonato-calix[8]arene are described, showing extremes in the macrocyclic conformation; one is planar and nearly circular, the other an inverted double cone. The differences in the molecular conformations lead to highly different packing arrangements in the structures.

Solid state structures of the complexes between the antiseptic chlorhexidine and three anionic derivatives of calix[4]arene

The solid state structures of the complexes between antiseptic chlorhexidine and three anionic calix[4]arene derivatives are described. Each of the three calixarenes shows typical self-organisation in the solid-state that will further impose a specific complexation of the active molecule in the co-crystal.

Assembly modes in the solid state structure of the complexes of melamine mono- cations with para -calix[4]arene sulfonic acid and calix[4]arene dihydroxyphosphonic acid

The crystal structures of the complexes between melamine mono-cations and para-calix[4]arene sulfonic acid and calix[4]arene dihydroxyphosphonic acid have been determined. In both cases the structure is based on a bilayer motif of calixarene molecules intercalated by motifs of melamine mono-cations. While in the complex with calix[4]arene dihydroxyphosphonic acid the motifs of melamine cations are parallel to the in-layer arrangement of the calixarene, for para-sulfonatocalix[4]arene there is 17.6° displacement between the axes of the two motifs generating a laminate structure.

Kinetic trapping of the host–guest association intermediate and its transformation into a thermodynamic inclusion complex

The molecular recognition and self-assembly between host cucurbit[6]uril and guest adrenaline led to kinetic trapping and crystallization of the intermediate exclusion complex, which was characterized by X-ray diffraction. The crystalline kinetic complex undergoes slow spontaneous dissolution and subsequently recrystallizes as a thermodynamic inclusion complex.

Supramolecular versatility in the solid-state complexes of para-sulphonatocalix[4]arene with phenanthroline

The solid state structures of four complexes between para-sulphonato-calix[4]arene and phenanthroline have been determined. Three are simple complexes between the two molecules however the fourth contains aluminium cations, from a solid state extraction involving aluminium foil used in the weighing step. The phenanthroline cations are involved both in inclusion and also in various assemblies formed by aromatic–aromatic stacking.

A Thermo- and Photo-Switchable Ruthenium Initiator For Olefin Metathesis.

A ruthenium carbene complex bearing azobenzene functionality is reported. The complex exists in the form of two isomers differing by the size of the chelate ring. Both isomers were isolated by applying kinetic or thermodynamic control during the synthesis and characterized by X-ray diffraction analysis. The isomerization of the complex was studied by UV/Vis spectroscopy. The stable isomer was tested as a catalyst in olefin metathesis. The complex was activated at about 100 °C to promote ring-closing and ring-opening polymerization metathesis reactions. The activation took place also at room temperature under middle ultraviolet radiation.

Solvent control in the formation of supramolecular host–guest complexes of isoniazid with p-sulfonatocalix[4]arene

Here we demonstrate the solvent role in the cocrystallization of anti-tuberculosis drug isoniazid INH with macrocyclic host p-sulfonatocalix[4]arene C4S. The host–guest inclusion complex of INH with C4S crystallizes from aqueous solution. Altering the crystallization medium to water–cosolvent mixtures results in the formation of C4S-INH exo complexes, where the host cavity becomes occupied by a solvent molecule.

Monolayers of an amphiphilic para-carboxy-calix[4]arene act as templates for the crystallization of acetaminophen.

The title compound, 5,11,17,23-tetra-carboxy-25,26,27,28-tetradodecyloxy-calix[4]arene, 1, has been studied at the air-water interface, self-assembled as Langmuir monolayers, for its ability to interact with an active pharmaceutical ingredient (API), acetaminophen (APAP), and to initiate its crystallization. The Π/A isotherm study shows that there is a clear interaction between 1 and APAP causing an expansion of the monolayer. In addition to the known phase transition occurring at a surface tension of 38 mN m(-1), an additional kink is observed in the compression isotherm for concentrations of APAP above 40 mM suggesting that this API is causing an additional phase transition of the monolayer. Interface-initiated crystallization studies show that the presence of a monolayer spread on a supersaturated solution of APAP (26 g L(-1)) triggers this API crystal growth from the interface. The transfer of 1-based monolayers on glass surfaces has been carried out using the Langmuir-Blodgett technique. The so-produced monolayers have been shown to template the crystallization of APAP. LB films of 1 have characterized using imaging and spectroscopic ellipsometry. The results suggest that each monolayer has an average thickness of 18 Å, which is consistent with the molecular structure of 1 self-organized parallel to the interface with the alkyl chains pointing out parallel to the axis of the macrocycle and without interdigitation of the alkyl chains. The presence of APAP in the subphase during the LB transfer causes a limited but relevant increase in the layer thickness. The study of the capabilities of the LB films to initiate crystallization of APAP is also demonstrated showing the influence of the monolayer packing on the quantity of formed crystals.

Solid-state assembly of carboxylic acid substituted pillar[5]arene and its host–guest complex with tetracaine

The solid state structures of the carboxylic acid substituted pillar[5]arene PA5 host–guest complexes with ethanol and the anesthetic drug tetracaine are reported. PA5 forms an inclusion complex with ethanol in a 1 : 2 stoichiometry that assembles into hydrogen-bonded polymeric chains in the solid state. The macrocyclic cavity of PA5 can include large pharmaceutical molecules like tetracaine via a combination of different non-covalent interactions.

Host–guest complexes of cucurbit[6]uril with isoprenaline: the effect of the metal ion on the crystallization pathway and supramolecular architecture

We report on the three host–guest complexes between the cucurbit[6]uril macrocycle and the catecholamine drug isoprenaline obtained in the presence of magnesium or calcium ions. The metal ions affect both the crystallization pathway of the CB6–isoprenaline complexes and the supramolecular architecture in the solid state. In the case of the magnesium cations the sequential crystallization of the metal-free and the magnesium containing forms of the host–guest complexes was observed, while the use of calcium cations resulted in the direct crystallization of the calcium-coordinated CB6–isoprenaline complex.