- Bimolecular fluorescence quenching of benzoxazole/benzothiazole-based functional dyes
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Four dyes that belong to the group of hemicyanines and possess benzoxazole and benzothiazole moieties are synthesised and described. The spectroscopic properties of these compounds in 1-methyl-2-pyrrolidinone (MP) were studied. Synthesised dyes absorb in the UV–Vis region. The emission spectra are broad with a maximum located at approximately 500–520 nm. The deactivation of excited states of the synthesised molecules by various quenchers is also presented. The fluorescence quenching parameters were calculated using the Stern-Volmer equation. It was found, that the fluorescence quenching of the excited dye by quencher molecules occurs. The fluorescence quenching rates (kq) are about 1010 M?1 × s?1.
- Balcerak, Alicja,Kabatc, Janina
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- Excimers beyond pyrene: A far-red optical proximity reporter and its application to the label-free detection of DNA
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A family of organic chromophores that, like pyrene, forms emissive excimers is reported. Their chemical and photophysical properties are superior to pyrene for the design of chemo- and biosensors. Unlike hydrophobic pyrene, which requires excitation by cell-damaging UV irradiation, these polar dyes absorb strongly in the visible range, and their excimers emit brightly in the red to far-red region of the electromagnetic spectrum. The intensity of the emission signal is greatly increased upon formation of a preassociated dimer that is triggered upon aggregation or crystallization. In demonstration of the potential of this new family of excimer-forming dyes, a probe that is capable of detecting label-free DNA in water down to 10 pM and also doubles as a visualization agent for DNA in gel electrophoresis is reported.
- Han, Garam,Kim, Dongwook,Park, Younbong,Bouffard, Jean,Kim, Youngmi
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supporting information
p. 3912 - 3916
(2015/03/30)
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- Photoisomerization of trans-2-[4′-(dimethylamino)styryl]benzothiazole
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Photoreaction of trans-2-[4′-(dimethylamino)styryl]benzothiazole (t-DMASBT) under direct irradiation has been investigated in dioxane, chloroform, methanol and glycerol to understand the mechanism of photoisomerization. Contrary to an earlier report, isomerization takes place in all these solvents including glycerol. The results show that restriction on photoisomerization leads to the increase in fluorescence quantum yield in glycerol. The results are consistent with the theoretically simulated potential energy surface reported earlier using time-dependent density functional theory (TDDFT) calculations. DFT calculations on cis isomers under isolated condition have suggested that cis-B conformer is more stable than cis-A conformer due to hydrogen-bonding interaction. In the ground state, cis-DMASBT is predominantly present as cis-B. The fluorescence spectra of the irradiated t-DMASBT suggested that photoisomerization follows not the adiabatic path as proposed by Saha et al., but the nonadiabatic path. Contrary to an earlier report, the photoisomerization of trans-2-[4′-(dimethylamino)styryl]benzothiazole occurs in all the solvents including viscous glycerol and it follows not the adiabatic, but the non-adiabatic path. Relative higher fluorescence quantum yield obtained in glycerol is due to restriction on photoisomerization. 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology
- Mishra, Anasuya,Thangamani, Arumugam,Chatterjee, Soumya,Chipem, Francis A. S.,Krishnamoorthy, Govindarajan
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p. 247 - 252
(2013/03/13)
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- Synthesis and study of novel benzothiazole derivatives with potential nonlinear optical properties
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The synthesis of new benzothiazole push-pull systems as candidates for NLO-phores is described. Spectral (UV/VIS and solvatochromic) and theoretical studies (electronic properties based on semiempirical AM1 and PM3 methods) of the prepared compounds were carried out. The structure and physico-chemical parameters affecting the push-pull character and intramolecular charge transfer (ICT) of the studied compounds have been investigated and compounds with enhanced hyperpolarizability β have been predicted. The benzothiazolium salts were found to be much more effective NLO-phores in comparison with the corresponding neutral benzothiazoles. The 4-NPh2 group is the most effective donor. The extension of conjugated bridge improves the studied NLO characteristics. An additional acceptor group bonded to the heterocycle causes a red shift of λmax but does not increase hyperpolarizability.
- Sigmundova, Ivica,Zahradnik, Pavol,Loos, Dusan
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p. 1069 - 1093
(2008/12/22)
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- Utilities of olefin derivatives
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Compounds having an activity to enhance the expression of apoAI are provided. Compounds of formula (I): in which Ar1 and Ar2 are independently a phenyl, naphthyl, or monocyclic or bicyclic aromatic heterocyclic group, which may be optionally substituted; —X— is —N═CZ2-, —CY2═CZ2-, —CY2Y3—CHZ2-, —S—, —O—, or the like; Y1, Y2, Y3, Z1 and Z2 are independently a hydrogen, a halogen, a lower alkyl, a phenyl, or the like; Z1 and Z2 may be independently a linker group that may combine with Ar2 and Ar1 to form a condensed ring; m is 0 or 1, and n is 0 to 2; a prodrug thereof, a pharmaceutically acceptable salt or solvate of them; are disclosed.
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Page/Page column 22; 32
(2008/06/13)
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- Benzazole compounds
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There are disclosed herein benzazole compounds, exemplified by 2-(4-aminophenyl)benzothiazole and analogues or salts thereof, which exhibit very significant selective cytotoxic activity in respect of tumor cells, especially breast cancer cells, and which provide potentially useful chemotherapeutic agents for treatment of breast cancer.
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- Facile synthesis of 1,2-diaryl- and triarylethenes with supported fluoride bases
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Differently substituted arenecarbaldehydes, mainly benzaldehydes, can be very efficiently condensed with a wide variety of methylbenzenes having an electron-withdrawing group in the para-position, as well as with fluorenes, xanthene, cyclopentadienes and indenes by using a standardized KF- or CsF-Al2O3 base system in dimethylformamide.
- Hellwinkel,Goke,Karle
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p. 973 - 978
(2007/10/02)
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- Styryl and azastyryl 1,3-benzazoles with antihelmitic activity
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New 2-benzylideneimino- and 2-styryl-1,3-benzimidazole and benzothiazole derivatives have been prepared and tested in vitro against Caenorhabditis elegans, and Heligmosomoides polygyrus, showing some of them, interesting properties as inhibitors, which were not observed in the complementary in vivo tests. In order to rationalize the activity, log P was measured for all compounds, and QSAR models were developed, allowing the optimisation of the in vitro activity.
- Cuadro,Perez-Butragueno,Pastor-Maeso,Varez-Builla,Martinez-Grueiro,Martinez-Fernandez
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p. 477 - 488
(2007/10/02)
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