“Cold” Synthesis of a New Antidepressant Drug S 3344

A “cold” synthetic route to 7-(4-fluorobenzylamino)-8-methylnonanoïc acid, a new antidepressant drug, is reported. This method can be used to obtain the tritium labelled compound in C₈-C₉ position. The synthesis involves introduction of double bond on the aliphatic chain, reduction of this and hydrolysis in alkaline medium of the ester function.     

Selective mono-N-alkylation of triethylenetetraamine. A new versatile route to polylinear aza-ligands

A new route to triethylenetetraamine selective mono-N-alkylation on secondary nitrogen atom using simultaneously bisaminal and diamide protections is presented and applied to the synthesis of poly-linear aza-ligands.     

Cholesteric liquid crystalline materials reflecting more than 50% of unpolarized incident light intensity

Cholesteric liquid crystals (CLCs) selectively reflect light when the wavelength matches the helical pitch. The reflectance is limited to 50% of ambient, unpolarized light because only circularly polarized light of the same handedness as the helix is reflected. Here the elaboration procedure and the properties of a CLC gel whose optical characteristics go beyond the 50% reflectance limit are reported. Photopolymerizable monomers are introduced into the volume of a CLC exhibiting a thermally induced helicity inversion and the blend is then cured with UV light when the helix is right-handed. The reflectance exceeds 50% when measured at the temperature assigned at a cholesteric helix with the same pitch but a left-handed sense before reaction. The reflection properties are investigated in the infrared region. From scanning electron microscopy investigations, it is shown that the organization of the mesophase is transferred onto the structure of the network. The gel structure is discussed as consisting of a polymer network with a helical structure containing two populations of low molar mass LC molecules. Each of them is characterized by a band of circularly polarized light which is selectively reflected. The monitoring of the optical response with temperature offers the opportunity to discriminate the respective contributions of the bound and free fractions of LC molecules to the reflectance, and to give evidence of the progressive increase of the reflected flux when the temperature decreases from the curing temperature. Novel opportunities to modulate the reflection over the whole light flux range are offered. Potential applications are related to the light management for smart windows or reflective polarizer-free displays with a larger scale of reflectivity levels.     

Alkynylgold(I) C3-Chiral Concave Complexes: Aggregation and Luminescence

Chiral gold(I) acetylide trinuclear complexes 1 – 3 based on the cyclotribenzylene platform and terminal PR₃ ligands (R=Ph, Et, and Cy, respectively), were characterized and their light emission studied. They exhibited long-lived blue phosphorescence in CHCl₃ and a weak fluorescence in the UV. In MeOH/CHCl₃ mixtures of >1:1 volume ratio, 1 and 2 exhibited a new emission band at ca. 540 nm that developed at the expense of the UV emission. DLS studies demonstrated the presence of molecular aggregates of Ø 30–80 nm. The green emission observed in MeOH-rich solvent mixtures was therefore induced by aggregation, and could originate from Au⋅⋅⋅Au interactions. The AIE spectrum of 3 was observed only in solutions containing 99 % of MeOH, and correlated with its solid state emission. The AIE profiles of the enantiomers of 1 differed from that of rac- 1 , suggesting that the latter is a true racemate.     

Electrochemical precipitation of neptunium with a micro electrochemical quartz crystal microbalance

Journal of Radioanalytical and Nuclear Chemistry - Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and...     

Conformational Analysis of Acyclic α-Fluoro Sulfur Motifs

Bioactive small molecules containing α-fluoro sulfur motifs [RS(O)_nCH₂F] are appearing with increasing frequency in the pharmaceutical and agrochemical sectors. Prominent examples include the anti-asthma drug Flovent^® and the phenylpyrazole insecticide pyrafluprole. Given the popularity of these structural units in bioactive small molecule design, together with the varying oxidation states of sulfur, a conformational analysis of α-fluoro sulfides, sulfoxides, and sulfones, would be instructive in order to delineate the non-covalent interactions that manifest themselves in structure. A combined crystallographic and computational analysis demonstrates the importance of hyperconjugative donor-acceptor interactions in achieving acyclic conformational control. The conformational disparity in the syn- and anti-diastereoisomers of α-fluorosulfoxides is particularly noteworthy.