A cuvette and the technique for circular dichroism measurements of molecules oriented in a liquid crystal matrix

Chiroptical Properties of cisoid Enones from Circular Dichroism (CD) and Anisotropic Circular Dichroism (ACD) Spectroscopy

“…For an induced cholesteric phase, in general, the suprastructural chirality [16±18] can be eliminated applying an electric AC or DC field large enough to unwind the helix (10 6 V m À1 ). As a result, CD spectra can be measured [20] in the obtained uniaxial liquid crystal unidomain in a commercial CD instrument with the applied electric field parallel to the propagation direction of the light beam (optical axis of the phase). [16] The error of De is about 2 % whereas that of De A is around 5 to 20 %.…”

“…[20]. ZLI-1695 (Merck mixture of four 4n-alkyl-4'-cyanobicyclohexanes) has been used as the liquid crystal host phase for orienting the cisoid enones throughout this paper.…”

Chiroptical Properties of the Cisoid Enone Chromophore

“…The sample, filled in a special cuvette, and then adjusted in a commercial CD instrument with the optical axis parallel to the propagation direction of the light beam enables the measurement of the ACD. The sample is free of linear dichroism effects if the measured effect is independent of rotation of the sample (cuvette) about the propagation direction of the light beam.…”

“…Circular Dichroism of Anisotropic Samples (ACD). The ACD (circular dichroism of oriented molecules − ) and polarized UV spectra (absorption of parallelly and perpendicularly polarized light 21 ) provide a refined structural information in addition to the UV and CD spectra. For the measurements of ACD and polarized UV molecules have to be brought into a partially ordered state (see Appendix and Experimental Section).…”

Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism

“…These interfering effects must therefore be eliminated or at least minimised; the best way of achieving this is aligning the optic axis with the incident beam, so that the material acts as if it was optically isotropic. 33 In this work we investigated the chirality of the low-T nematic (Nx) in two series of bimesogenic compounds: diterphenyls DTC5Cn (n = 5, 7, 9) and dicyanobiphenyls CBCnCB (n=7, 9), where n is the number of methylene groups in the spacersee Figure 2a. These are two archetypal and moststudied series of Nx-forming bimesogens, so the results obtained here can be regarded as representative of bent flexibly-linked bimesogens.…”