Investigation of the crystal structure of two amphiphilic diols

Abstract

The crystal and molecular structures of (R)-4′-(2,3-dihydroxypropyloxy)-4-cyanobiphenyl, 1 and 4′-(cis-cis-3,5-dihydroxycyclohexyloxy)-4-cyanobiphenyl, 5 have been determined. The packing of compound 1 occurs in sheets, with a dense hydrogen bonding network within the layer of one sheet and to the next sheet, whereby the cyano groups are incorporated into the hydrogen bonding network. The hydrogen bonding scheme of compound 5 involves a water molecule; there is some disorder with regard to the hydrogen atoms bound to the water molecules.     

The Quest for β-Thiolactam Antibiotics

Thioketenes or thioketene equivalents give β-thiolactams in the reaction with C=N systems, but problems arise in the synthesis of highly functionalized derivatives. Therefore to obtain the thione analog of a bactam a thionation approach was chosen.     

Catalytic transformation of silicon tetraisocyanate Si(NCO)4 to a polymeric silylcarbodiimide

A new way for the preparation of inorganic polymeric carbodiimide‐based networks is presented which resembles the transformation of molecular isocyanates using 1‐phenyl‐3‐methyl‐2‐phospholene‐1‐oxide as a catalyst. The respective reaction sequence, well established in preparative organic chemistry, has been applied for the synthesis of carbodiimide‐based SiNC(O) materials. Starting from Si(NCO)₄ (silicon tetraisocyanate), a transformation to an insoluble extended inorganic array was achieved in boiling dodecan (T = 216 °C). Analysis of the polymer using X‐ray diffraction, FT‐IR, density measurement, matrix‐assisted laser desorption/ionization time of flight and TGA revealed that this highly moisture‐sensitive amorphous network consists of oligomers of high molar mass and exhibits a high density of around 1.5 g cm^?3, which corresponds quite well to the calculated density of crystalline Si(NCN)₂ reported in the literature. Degradation of this 'SiNC(O) phase' with the release of N₂ and (CN)₂ finally provided SiC as the only crystalline product. No indication of the formation of crystalline Si₃N₄ or intermediate crystalline 'SiC₂N₄', silicon carbodiimide (= Si(NCN)₂), was noticed. Copyright © 2013 John Wiley & Sons, Ltd.     

Phase behaviour of amphiphilic side-chain polymers

The present study describes the phase behaviour of a low-molar-mass 1,3-diol with a linear alkyl chain in aqueous solution. From the combined results of differential scanning calorimetry and optical polarizing microscopy a phase diagram was constructed. The low-molar-mass diol forms a lamellar mesophase only in the presence of water. The influence of the linkage of the amphiphilic molecule to different polymer backbones on the stability of the mesophase was investigated. It is evident that amphiphilic side-chain polymers show a distinct stabilization of the mesophase. Moreover, comparison between the polyacrylate, polymethacrylate and polysiloxane indicates a strong influence of the main-chain flexibility on the stability of the liquid-crystalline phase. The type of the liquid-crystalline phase of the side-chain polyacrylate in the water-saturated state was identified by X-ray investigations as lamellar. The hydration behaviour of the polymers was investigated by ²H-N.M.R. and isopiestic measurements.