Roland Stolarski

Fluorescent perylene dyes for liquid crystal displays

Abstract A number of alkyl esters of perylene-3,4,9,10-tetracarboxyl acid have been synthesised. The structure of the dyes obtained was confirmed by 1 H-NMR, mass spectroscopy and elemental analysis. Their fluorescent properties in isotropic and anisotropic (nematic) media have been determined. Absorption and fluorescence order parameters of the dyes in liquid crystal mixtures of the ‘quest-host’ type have been determined. Liquid crystal displays containing the dyes have been constructed and a strong contrast on the fluorescent background achieved.

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.

The Spectral Properties of New Types of Fluorescence Dyes in Nematic Liquid Crystals

Abstract The spectral properties of the new class of fluorescent dyes in isotropic and anisotropic (liquid crystals) solvents have been investigated. The main purpose of these investigations was to get some information on these dyes in order to utilize them in colored liquid crystal displays. These dyes align well in nematic liquid crystals and have high fluorescence yield, therefore the authors tried to apply one of them in two various types of liquid crystal displays.

Fluorescent dyes for guest-host applications

Abstract The spectral properties of some fluorescent dyes (hicarboxilic acid derivatives) in isotropie solvents and nematic liquid crystals have been studied and the temperature of the nematic-isotropic phase transition for dye-liquid-crystal mixtures has been determined. It was found that the dyes investigated emit green light, are aligned well in nematic liquid crystals, have quite high fluorescence efficiency and do not destabilize the nematic phase of the host. They can therefore be utilized in ‘guest-host’ liquid crystal display devices.

Molecular organization in binary mixtures of derivatives of naphthalenebicarboxylic acid and naphthoylenebenzimidazole with a liquid crystal in two-dimensional layers II. Langmuir-blodgett films

Langmuir–Blodgett (LB) films of some dichroic dyes, namely derivatives of naphthalenebicarboxylic acid and derivatives of naphthoylenebenzimidazole, and of their mixtures with mesogens: 4‐octyl‐4′‐cyanobiphenyl or 4‐pentyl‐4″‐cyano‐p‐terphenyl were prepared. Absorption and fluorescence studies using unpolarized and linearly polarized light were carried out. Both absorption and fluorescence spectra indicated the formation of aggregates of dye molecules in monomolecular layers. Moreover, it was found that dye molecules are more tilted to the quartz surface in LB films than to the plane of the air–water interface in Langmuir films.

Iron complexed dyes based on 1,5-diaryl-3-cyanoformazanes

Abstract In the search for more environmental friendly dyes, the synthesis of new 1:2 iron complexes of 1,5-diaryl-3-cyanoformazanes was carried out. The structure and colouristic properties of 16 new dyes and their intermediates was characterised by 1 H NMR, FAB and UV–VIS spectroscopy. The products were used as acid dyes in the coloration of wool and polyamide fibres. Application, colouristic and fastness properties of the dyes were determined and discussed.

Studies on isomerism of 1:2 iron complexed dye based on 1-(5'-nitro-2'-hydroxyphenyl)-3-cyano-5-(4-sulphonamidophenyl)formazan

Abstract During the synthesis of previously described new 1:2 iron complexes of 1,5-diaryl-3-cyanoformazanes it was found that the metalisation process is dependent on the pH of the reaction media and in some cases two isomeric products appear. These isomers exhibited the same quantitative composition but different colours and physico-chemical properties. With the use of 1 H-NMR and IR analysis and the measurements of magnetic moments an attempt to attribute the chemical structure to both isomers of 1:2 type iron complex of 1-(5′-nitro-2′-hydroxyphenyl)-3-cyano-5-(4″-sulphonamidophenyl)formazan has been made.

Characterization of Pure and Mixed Langmuir and Langmuir-Blodgett Films of Some Fluorescent Naphthalimide Dyes

Abstract Langmuir and Langmuir-Blodgett (LB) films formed of some fluorescent dyes, derivatives of 4-aminonaphthalimide, and their binary mixtures with the liquid crystal 4-heptyl-4’-cyanobiphenyl (7CB) have been studied. Surface pressure versus mean molecular area isotherms for Langmuir films have given information about the alignment of molecules in a monomolecular layer at the air/water interface. The absorption and fluorescence spectra of LB films have revealed the occurrence of aggregates among dye molecules. In the ground electronic state some fraction of aggregates of J-type have appeared, while in the excited state the excimers have been created. The latter statement has been confirmed by additional absorption and fluorescence measurements performed for dyes dissolved in 7CB and placed in sandwich cells of 10 μm in thickness.

Synthesis and properties of some 9,10-dihydro-7H-imidazo[1,2-b]benz[d,e]isoquinolin-7-one derivatives

Abstract The various routes of synthesis of some methoxy- and acetylamino -9,10- dihydro -7H- imidazo [1,2-b] benz [d,e] isoquinolin-7-one derivatives are described. The mixtures of geometric isomers obtained were separated and the chemical constitution of individual isomers was confirmed by the u.v., i.r., n.m.r. and mass spectroscopy. The fluorescence properties of individual isomers were also determined .

Characterization of Langmuir Films of Naphthalimide Dyes Mixed with 4-Heptyl-4′-Cyanobiphenyl (7CB)

Langmuir films formed of derivatives of 4-aminonaphthalimide and their binary mixtures with the liquid crystal 4-heptyl-4′-cyanobiphenyl (7CB) have been studied. The films have been characterized by the surface pressure–area (π-A) and surface potential–area (ΔV-A) isotherms and by Brewster angle microscopy (BAM). Additionally, the electronic absorption spectra of a monolayer on the water surface at different stages of the film formation were recorded. On the basis of these spectra the conclusions about the ability of the dye molecules to form self-aggregates at the air–water interface have been drawn.