Benzothiazoles with tunable electron-withdrawing strength and reverse polarity: a route to triphenylamine-based chromophores with enhanced two-photon absorption.

A series of dipolar and octupolar triphenylamine-derived dyes containing a benzothiazole positioned in the matched or mismatched fashion have been designed and synthesized via palladium-catalyzed Sonogashira cross-coupling reactions. Linear and nonlinear optical properties of the designed molecules were tuned by an additional electron-withdrawing group (EWG) and by changing the relative positions of the donor and acceptor substituents on the heterocyclic ring. This allowed us to examine the effect of positional isomerism and extend the structure-property relationships useful in the engineering of novel heteroaromatic-based systems with enhanced two-photon absorption (TPA).

Photophysical properties and photostability of novel benzothiazole-based D-π-A-π-D systems.

The photophysical properties and photochemical stability of two novel D-π-A-π-D systems based on a benzothiazole core and terminal N,N-dimethylaminophenyl and N,N-diphenylaminophenyl groups were investigated. The quantum yield of photoreactions (Φ) was determined for various oxygen concentrations in the solvent (CH2Cl2) and various irradiation wavelengths. Trans-cis photoisomerization is proposed as a photobleaching mechanism during irradiation at longer wavelength due to charge-transfer transitions.

Benzothiazole-based fluorophores of donor-pi-acceptor-pi-donor type displaying high two-photon absorption.

A series of novel heterocycle-based dyes with donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) structural motif, where benzothiazole serves as an electron-withdrawing core, have been designed and synthesized via palladium-catalyzed Sonogashira and Suzuki-type cross-coupling reactions. All the target chromophores show strong one-photon and two-photon excited emission. The maximum two-photon absorption (TPA) cross sections delta(TPA) of the prepared derivatives bearing diphenylamino functionalities occur at wavelengths ranging from 760 to 800 nm and are as large as approximately 900-1100 GM.

Chemogenomic and transcriptome analysis identifies mode of action of the chemosensitizing agent CTBT (7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine).

Background: CTBT (7-chlorotetrazolo [5,1-c]benzo[1,2,4]triazine) increases efficacy of commonly used antifungal agents by an unknown mechanism. It increases the susceptibility of Saccharomyces cerevisiae, Candida albicans and Candida glabrata cells to cycloheximide, 5-fluorocytosine and azole antimycotic drugs. Here we elucidate CTBT mode of action with a combination of systematic genetic and transcriptome analysis.

New conjugated benzothiazole-N-oxides: synthesis and biological activity.

Eleven new 2-styrylbenzothiazole-N-oxides have been prepared by aldol - type condensation reactions between 2-methylbenzothiazole-N-oxide and para-substituted benzaldehydes. Compounds with cyclic amino substituents showed typical push-pull molecule properties. Four compounds were tested against various bacterial strains as well as the protozoan Euglena gracilis as model microorganisms.

The impact of the pi-electron conjugation on (15)N, (13)C and (1)H NMR chemical shifts in push-pull benzothiazolium salts. Experimental and theoretical study.

The (15)N as well as (13)C and (1)H chemical shifts of eight push-pull benzothiazolium iodides with various pi-conjugated chains between dimethylamino group and benzothiazolium moiety have been determined by NMR spectroscopy at the natural-abundance level of all nuclei in DMSO-d(6) solution. In general, the quaternary benzothiazolium nitrogen is more shielded [delta((15)N-3) vary between - 241.3 and - 201.

Spectroscopic study of 2-[2-(4-cyclaminophenyl)ethen-1-yl] benzothiazoles and their N-allylbenzothiazolium bromides. Solvent and substituent effects on their ultraviolet-visible and fluorescence spectra.

UV-vis and fluorescence spectra of 2-[2-(4-cyclaminophenyl)ethen-1-yl] benzothiazoles 1 and their N-allylbenzothiazolium bromides 2 have been measured and interpreted. The substitution and solvent effects on electronic structure and spectra have been investigated. The benzothiazolium salts substituted with saturated cyclamines show strong push-pull character and can be used as potential NLO materials.