Wyniki wyszukiwania - BazTech

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Właściwości elektroluminescencyjne niektórych układów heterocyklicznych z grupy 1H-pirazolo[3,4-b]chinolin

Gondek E., Daniel A., Pokladko M., Otowski W., Sanetra J., Mac M.

Czasopismo Techniczne. Nauki Podstawowe

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2009

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R. 106, z. 1-NP

85-93

PL

W artykule przedstawiono wyniki badań elektrooptycznych wybranych luminoforów z grupy układów azaheterocyklicznych. Zbudowano jednowarstwowe diody ITO/MOL+PVK/Ca/Al, w których warstwę aktywną stanowiła mieszanina luminofory z tej grupy oraz polimeru matrycowego PVK. Zebrano i omówiono właściwości fotofizyczne molekuł.

EN

In this paper the synthesis of some new chromophores which could be used in organic LED fabrication are presented. All of them are pyrazoloquinoline derivatives. They were characterized by absorption and photoemission spectroscopy. Some were used, dispersed in poly(N-vinylcarbazole) (PVK) matrix, as the emissive layer in LED structure.

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Photophysical Properties of Derivatives of 1H-Pyrazolo[3,4-b]quinoline and 1H-Pyrazolo[3,4-b]quinoxaline

Mac M., Uchacz T., Andrzejak M., Danel A., Szlachcic P., Nowak P.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 4

EN

The fluorescence behaviour of 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline (PQ1), 1,3- diphenyl-1H-pyrazolo[3,4-b]quinoxaline (PQX1) and 3-methyl-1-phenyl-1H-pyrazolo[ 3,4-b]quinoxaline (PQX2) has been compared. It has been established that these dyes form exciplexes with N,N-dimethylaniline (DMA) and p-cyano N,N -dimethylaniline (DMABN) in weakly polar dibutyl ether. The reduction potential of these compounds has been measured by cyclic voltammetry. The different behaviour with respect to intersystem crossing process in pyrazoloquinoline and pyrazoloquinoxalines has been explained in terms of larger energy gap between the first excited singlet state and the higher triplet state having a different symmetry in the former system. This is supported by quantum chemical calculations and it explains the lack of the triplet-triplet absorption bands in the flash photolysis experiments in pyrazoloquinoline system in any solvent.

3

Fluorescence Properties of Derivatives of Anthroic Acids

Mac M., Danel K., Andrzejak M.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 10

1737-1754

EN

Fluorescence behaviour of 9-anthracenecarboxylic acid (H-ANCOOH), 10-bromoanthracene- 9-carboxylic acid (Br-ANCOOH) and 10-cyanoanthracene-9-carboxylic acid (CN-ANCOOH) in solvents of different polarities was investigated, using the steady state and time-resolved methods. The dual fluorescence of the acids originates clearly from the fluorescence of the undissociated acids and the anions. From the ground-state absorptiometric titration thepKavalues have been obtained, whereas for the values of pKa in the excited singlet state (pKa * ) the Förster cycle was used. Introduction of the electron withdrawing groups (Br and CN) shifts the pKa values both in the ground and singlet excited states to the lower values compared to the parent molecule. On the other hand, the presence of the electron accepting groups in anthracene moiety influences the spectral position of the bimolecular exciplexes (excited state complexes) formed between the excited acids and the electron donor molecule, such as p-cyano, N,N-dimethylaniline (DMABN) in nonpolar solvents. A correlation between the decreasing pKa values in the excited singlet state and the position of the charge transfer luminescence of the intermolecular exciplexes has been found.

4

Photodehalogenation of 9,10-Dichloroanthracene Induced by Electron Transfer Fluorescence Quenching with Primary and Tertiary Amines in Acetonitrile and n-Hexane. Salt Effect on Photodechlorination Process

Mac M.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 4

427-439

EN

Quenching of 9,10-dichloroanthracene (DCA) fluorescence by primary or tertiary amines in acetonitrile solution results in formation of DCAradical anions, amine radical cations and triplet DCA, which were observed by nanosecond flash photolysis. In n-hexane, only the triplet-triplet absorption of DCA is observed. Rate constants of back electron transfer from the solvent separated radical ion pair (SSRIP), kbet, were calculated from the quantum yields of charge separation and triplet state formation by assuming a rate of 5_108 s-1 for ion separation from the SSRIP. The rate constants kbet follow the trends expected from the electron transfer theory (inverted Marcus region). Proton transfer from radical cation of primary amine to the radical anion of DCA, occurring in the contact radical ion pair (CRIP) has been found to be the decisive step for photodehalogenation in n-hexane. Importance of the heavy atom effect has been discussed on the basis of photophysical scheme, describing the processes occurring in the CRIP (SSRIP). It has been found, that lithium perchlorate catalyses the photodechlorination of DCA in acetonitrile solution, due to acceleration of the charge separation and retardation of the recombination of formed radical ion pair.