Polyene Type Research Articles

Infrared absorption spectra of functional derivatives of 5-nitrofurfuryl-2-polyalkenes and intramolecular interaction

The frequency characteristics of the vibration spectra of a number of polyalkene derivatives of 5-nitrofuran are examined. In particular, the IR spectra vibrations frequencies of the furan ring, nitro group, double bonds, and carbonyl group are examined with respect to the near and more remote intramolecular environment. The effects of intramolecular interaction, transmitted both through a chain of a 2-substituted system of the polyene type, and through a system of furan ring double bonds, are determined. The problem of the aromaticity of the furan ring is considered.

New Types of Polyenes with Cyclic Cross‐Conjugated Bond Systems

New Types of Polyenes with Cyclic Cross‐Conjugated Bond Systems

Structure of an one-dimensional chain of the polyene type

Structure of an one-dimensional chain of the polyene type

A new trichothecin-like antifungal antibiotic.

IN a screening programme for antibiotic effects of Basidiomycetes we found a strain which inhibited Candida albicans. The antifungal substance was produced by this strain in surface and submerged culture in a medium containing peptone, glucose, inorganic salts and aneurin. The substance for which we provisionally propose the name ‘antibiotic-T’ was easily extracted from the fermentation liquor by most of the usual solvents. After extraction with benzene and evaporation of the solvent the residue became crystalline within a few days. Recrystallization twice from methyl alcohol gave pure crystals (prisms), melting point 126°C.,[α]D 20 + 13.5°, c. 1 in chloroform. No ultra-violet absorption characteristic of antifungal antibiotics of the polyene type was found. The antibiotic contains no halogen, sulphur or nitrogen. Micro-analyses: found (per cent): carbon, 68.51; hydrogen, 7.6; and oxygen, 25.0. The substance is very slightly soluble in hot water and gives a neutral solution; it is soluble in alcohols and sunflower oil and readily soluble in non-polar solvents. Its solution in water is stable for two months, is thermo-stable at its boiling point, but is inactivated at pH 12 within a few hours.

Free-Electron Network Model for Conjugated Systems. II. Numerical Calculations

Numerical calculations are carried out on a large number of aromatic and polyene type conjugated molecules by the methods of the first paper of this series. These calculations include all energy levels, the wavelengths of the first four electronic transitions, the complete π-electron wave functions, the bond densities and bond orders, free valence and reactivities, and dipole moments. A method of estimation of bond lengths with a root-mean-square error of 0.016A is presented. Wherever possible, comparisons are made with experiment and with the results of the LCAO molecular orbital theory in the approximation developed by Coulson and Longuet-Higgins. The results in general are at least as good as those of the LCAO calculations.