Synthesis and properties of maleopimaric acid amides, imides and imidoamides with arylisoxazole and quinoline fragments

The method for maleopimaric acid N-(5-arylisoxazol-3-yl)amides synthesis has been developed by reaction of maleopimaric acid chloride with 3-amine-5-phenyl(4-methylphenyl)isoxazoles. N’-butyl-, N’-(2-hydroxyethyl)imides of maleopimaric acid N-(5-arylisoxazol-3-yl)amides were prepared. Heterocyclic imide – maleopimaric acid N-(quinolin-8-yl) imide was prepared by reaction of maleopimaric acid and 8-aminoquinoline in toluene at reflux in 97.1 % yield. It was established that refluxing of toluene solution of 8-aminoquinoline and maleated rosin, prepared by treatment of rosin with maleic anhydride and containing at least 50 % of maleopimaric acid, leads to the formation of maleopimaric acid N-(quinolin-8-yl)imide in 52.5 % yield (based on weight of maleated rosin). It was found by the methods of IR-, 1H NMR spectroscopy and mass-spectrometry that maleopimaric acid N-(quinolin-8-yl)imide consists of two diastereomeric atropisomers at 1:0.40 ratio. The biological properties of the prepared compounds were studied. It was established that maleopimaric acid N-(5-(4-methylphenyl)isoxazol-3-yl)amide possesses rotatory power (26 mkm-1) and may be used as chiral dopant to nematic LC for preparation of chiral LC-compositions.

Electronic Currents Induced by Optical Fields and Rotatory Power Density in Chiral Molecules

The electric dipole–magnetic dipole polarizability tensor κ′, introduced to interpret the optical activity of chiral molecules, has been expressed in terms of a series of density functions kαβ′, which can be integrated all over the three-dimensional space to evaluate components καβ′ and trace καα′. A computational approach to kαβ′, based on frequency-dependent electronic current densities induced by monochromatic light shining on a probe molecule, has been developed. The dependence of kαβ′ on the origin of the coordinate system has been investigated in connection with the corresponding change of καβ′. It is shown that only the trace kαα′ of the density function defined via dynamic current density evaluated using the continuous translation of the origin of the coordinate system is invariant of the origin. Accordingly, this function is recommended as a tool that is quite useful for determining the molecular domains that determine optical activity to a major extent. A series of computations on the hydrogen peroxide molecule, for a number of different HO–OH dihedral angles, is shown to provide a pictorial documentation of the proposed method.

Optical vector field rotation and switching with near-unity transmission by fully developed chiral photonic crystals

State-of-the-art nanostructured chiral photonic crystals (CPCs), metamaterials, and metasurfaces have shown giant optical rotatory power but are generally passive and beset with large optical losses and with inadequate performance due to limited size/interaction length and narrow operation bandwidth. In this work, we demonstrate by detailed theoretical modeling and experiments that a fully developed CPC, one for which the number of unit cells N is high enough that it acquires the full potentials of an ideal (N → ∞) crystal, will overcome the aforementioned limitations, leading to a new generation of versatile high-performance polarization manipulation optics. Such high-N CPCs are realized by field-assisted self-assembly of cholesteric liquid crystals to unprecedented thicknesses not possible with any other means. Characterization studies show that high-N CPCs exhibit broad transmission maxima accompanied by giant rotatory power, thereby enabling large (>π) polarization rotation with near-unity transmission over a large operation bandwidth. Polarization rotation is demonstrated to be independent of input polarization orientation and applies equally well on continuous-wave or ultrafast (picosecond to femtosecond) pulsed lasers of simple or complex (radial, azimuthal) vector fields. Liquid crystal–based CPCs also allow very wide tuning of the operation spectral range and dynamic polarization switching and control possibilities by virtue of several stimuli-induced index or birefringence changing mechanisms.

Net atomic charges, electric moments, and sign and magnitude of optical rotatory power in α-TeO2 at 296 K

Optical activity is determined from a point charge model in one enantiomorph of a chiral and semiconducting α-TeO2 crystal. Net atomic charges of Te and O atoms are iterated and electric moments derived. Second electric moments in the principal axis directions are calculated and their ratio is fitted by comparison with the corresponding ratio of the optical refraction indices. The components of the axial vectors are calculated and converted to the gyration tensor components. The optical rotatory power in the positive direction of the optic axis is determined, and the sense of optical rotation is defined from transformations of polar vectors of first rank of the TeO2 groups and visually confirmed in both enantiomorphs.

A Standard for Rotatory Power Measurement

<p class="Abstract">In Germany, the realisation and dissemination of the unit of rotatory power is a legal task of the national metrology institute aimed at ensuring the safe operation of ergometers for patients. At the Physikalisch-Technische Bundesanstalt, this task is carried out by means of a standard that can be operated both as a regulated brake and as a regulated drive, so that the effective torque and the revolution speed can be measured traceably. In this article, technical details and uncertainty calculations about this standard are given.</p>