Pharmaceutical polymorph control in a drug-mimetic supramolecular gel.

We report the synthesis of a bis(urea) gelator designed to specifically mimic the chemical structure of the highly polymorphic drug substance ROY. Crystallization of ROY from toluene gels of this gelator results in the formation of the metastable red form instead of the thermodynamic yellow polymorph. In contrast, all other gels and solution control experiments give the yellow form. Conformational and crystal structure prediction methods have been used to propose the structure of the gel and show that the templation of the red form by the targeted gel results from conformational matching of the gelator to the ROY substrate coupled with overgrowth of ROY onto the local periodic structure of the gel fibres.

Catalytic CO2-to-CO conversion in water by covalently functionalized carbon nanotubes with a molecular iron catalyst.

The covalent grafting of an Fe porphyrin on carbon nanotubes led to efficient electroreduction of CO2 into CO in water (pH 7.3). CO was obtained with high selectivity and turnover at 0.5 V overpotential. The grafting strategy may be further extended to various conductive and semi-conductive surfaces.

Photochemical and electrochemical catalytic reduction of CO2 with NHC-containing dicarbonyl rhenium(i) bipyridine complexes.

The electrochemical and photochemical catalytic reductions of CO2 using N,O and N,S-NHC-containing dicarbonyl rhenium(i) bipyridine complexes have been investigated. By replacing the carbonyl ligand in tricarbonyl rhenium(i) complexes with a weaker π-accepting ligand, the characteristic MLCT transitions shifted to lower energy. This makes photocatalysts capable of harvesting low-energy visible light for catalyzing CO2 reduction. A detailed study revealed that these dicarbonyl rhenium(i) complexes are also highly selective for photocatalysis of CO2 to CO with a good quantum efficiency (10%), similar to that of the tricarbonyl rhenium(i) complex analogues. From the electrochemical study, it was observed that the catalysts efficiently produce CO from CO2 with high turnover frequency and good stability over time.

Noncovalent Immobilization of a Molecular Iron-Based Electrocatalyst on Carbon Electrodes for Selective, Efficient CO2-to-CO Conversion in Water.

Catalysis of fuel-producing reactions can be transferred from homogeneous solution to surface via attachment of the molecular catalyst. A pyrene-appended iron triphenyl porphyrin bearing six pendant OH groups on the phenyl rings in all ortho and ortho' positions was immobilized on carbon nanotubes via noncovalent interactions and further deposited on glassy carbon. X-ray photoelectron spectroscopy and electrochemistry confirm catalyst immobilization. Using the carbon material, highly selective and rapid catalysis of the reduction of CO2 into CO occurs in water (pH 7.3) with 480 mV overpotential. Catalysis could be sustained for hours without loss of activity and selectivity, and high turnover number was obtained.

A water-soluble calix[4]arene-based ligand for the selective linear coordination and stabilization of copper(I) ion in aerobic conditions.

A number of serious diseases are linked to copper homeostasis dysfunction. The design of copper(I)-selective chelators is of particular interest not only for the creation of therapeutic objects but also as useful tools to gain insights into the coordination of copper(I) in a biological medium. A water-soluble Cu(I)-selective ligand that associates strong Cu(I) binding at pH = 7.4 (10(14) M(-1)), insensitivity to air, and selectivity toward Cu(II) and other biologically relevant cations is described.