Ewa Mykowska

Derivatives of 4-amino-N-ethylnaphthalimide for use in nematic liquid crystals

Abstract The order parameters of some dichroic fluorescent dyes {derivatives of 4-amino-N-ethylnaphthalimide} in three nematic liquid crystal mixtures (W52, E7 and ZLI 2359) have been determined by means of optical spectroscopy methods and the influence of the dye addition on the nematicisotropic phase transition temperature has also been investigated. The voltages characterizing the impact of the electric field on the dye-liquid crystal mixtures have been estimated. It was found that the dyes can be utilized in guest-host liquid crystal display devices.

Spectral properties of fluorescent dyes in nematic liquid crystals

Abstract The basic spectral properties and the orientation of some dichroic fluorescent dyes (derivatives of 4-amino-(N-ethylnaphthalimide)) in several nematic liquid crystal matrices have been studied. Moreover, the temperature of the nematic—isotropic phase transition for the dye—liquid crystal mixtures has been determined. It has been found that the dyes investigated are characterized by parameters which make them applicable to both passive and active “guest—host” liquid crystal display devices.

Molecular Orientation of Perylene-Like Dyes in Liquid Crystal 80CB

Abstract The polarized absorption and fluorescence spectra of some dichroic fluorescent dyes (derivatives of 3,4,9-perylenetricarboxylic acid and 3,4,9,10-perylenetetracarboxylic acid) oriented in liquid crystal 80CB have been recorded as a function of temperature. On the basis of these spectra the order parameters and and orientational distribution function have been determined. The conclusions about the influence of the molecular structure of the dyes on their orienting properties in uniaxial liquid crystalline phases have been drawn.

Spectral properties of derivatives of naphthoylenebenzimidazole in isotropic and liquid crystalline media

The spectral properties of some fluorescence dichroic dyes in isotropic solvents and nematic liquid crystals have been studied. The order parameter of the dyes in the anisotropic matrices has been determined by means of the polarized absorption and fluorescence measurements. The influence of the dye addition on the clearing temperature of the nematic host has been investigated. The main purpose of the investigation was to get some information on the dyes in order to use them in colored liquid crystal displays.

PERYLENE-LIKE DYES IN LIQUID CRYSTALLINE MEDIA

Abstract The spectral and electrooptical properties of some dichroic fluorescent dyes (derivatives of 3.4,9,10-perylenetetracorboxylic acid and of 3,4,9-perylenetricarboxylic acid) in isotropic solvents and nematic liquid crystals have been studied. The order parameter of the dyes in the anisotropic matrices has been determined by means of optical spectroscopy methods. Moreover, the influence of the dye addition on the nematic-isotropic phase transition temperature of the pure host has been investigated. It was found that some of the dyes studied can be utilized in guest-host liquid crystal display devices.

Influence of substituent length in dichroic dye molecules on the orientational properties of guest-host liquid crystal mixtures

Abstract The polarized absorption spectra of eight dichroic dyes, alkyl derivatives of 4-amino-(N-ethylnaphthalimide) dissolved in the nematic liquid crystals 5CB and 6CHBT have been measured as a function of temperature. On the basis of these spectra, the guest order parameter has been evaluated. The influence of the alkyl chain length of the dye molecule on the molecular orientation has been examined. Moreover, the nematic-isotropic transition temperatures for the dye-liquid crystal mixtures have been determined. The experimental results have been compared in some detail with calculations made on the basis of the mean field theory for binary mixtures.

Molecular Orientation of Some Fluorescent Dichroic Dyes in Nematic Liquid Crystal

Highly fluorescent dyes, derivatives of 1,8-naphthalimide and 3-benzanthrone, have been studied for use in liquid crystal displays of the “guest-host” type. Special attention has been given to the evaluation of the orientation of the dyes with planar molecular structure in the nematic liquid crystalline phase. By means of polarized absorption and emission spectroscopy, the order parameters SA, SF and D of the dyes in the liquid crystal mixture ZLI 1695 have been determined. Moreover, the absorption transition moment directions with respect to the long molecular axis of the dyes have been assigned.

Linear dichroism of dyes used in liquid crystal displays

The absorption spectra of some dichroic dyes: derivatives of naphthalenebicarboxylic acid and of naphthoylenobenzimidazole in nematogenic liquid crystalline mixture ZLI 1695 have been studied in details using polarized light. On the basis of these spectra the order parameters S and D have been determined by using the theoretical relation D equals f(S) and proper calculation procedure. Moreover, the absorption transition moment directions with respect to the long axis of the dye have been assigned.

Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye

AbstractThe long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate