Synthesis and characterization of linear 1,4-diazine-triphenylamine–based selective chemosensors for recognition of nitroaromatic compounds and aliphatic amines / E. V. Verbitskiy, Y. A. Kvashnin, E. F. Zhilina [et al.] // Dyes and pigments. - 2020. - Vol. 178. - P108344 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): ALIPHATIC AMINES -- FLUORESCENCE QUENCHING -- NITROAROMATIC COMPOUNDS -- PYRAZINE -- QUINOXALINE -- SOLVATOCHROMISM Аннотация: Novel 1,4-diazine-based dyes of the D–π–A type, possessing triphenylamine as an electron-donating group, have been developed. Fluorescence studies have demonstrated that emission of these fluorophores is sensitive towards different nitroaromatic compounds and aliphatic amines, both in solutions and in a vapor phase. Moreover, these compounds can be considered as “naked-eye” fluorescent probes for solution polarity because they possess pronounced solvatochromic properties. Therefore, these compounds have to be regarded as potential multifunctional chemosensors for monitoring hazardous organic substances. |
Synthesis and photophysical studies of novel v-shaped 2,3-bis{5-aryl-2-thienyl}(dibenzo[f,h])quinoxalines / T. N. Moshkina, E. V. Nosova, A. E. Kopotilova [et al.] // Asian journal of organic chemistry. - 2020. - Vol. 9, № 4. - P673-681 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CROSS-COUPLING -- DIBENZO[F,H]QUINOXALINE -- DONOR-ACCEPTOR-DONOR CHROMOPHORES -- FLUORESCENCE -- SENSORS Аннотация: A series of novel V-shaped luminophores containing electron-withdrawing dibenzo[f,h]quinoxaline core and arylthienyl donor fragments at positions 2 and 3 has been synthesized. The absorption spectra (UV/vis) were recorded in several solvents, whereas emission spectra were recorded in solutions and powders. The solvatochromism as well as halochromism of obtained compounds was also explored. Electronic-structure calculations using quantum-chemistry methods were performed to further analyse experimental results. All characteristics were compared with that of 2,3-bis(arylthienyl)quinoxaline counterparts. The halochromic effect studies showed that upon gradual addition of trifluoroacetic acid (TFA) to the toluene solution of diethylaminophenyl-substituted dibenzo[f,h]quinoxaline chromophore, absorption and emission changed. Observed band shifts were more distinct in the case of mentioned quinoxaline than for other derivatives. All of the (dibenzo[f,h])quinoxaline chromophores exhibited good sensitivity toward nitro-containing explosives with high Stern-Volmer constants up to 57800 M−1, these results are remarkable for such heterocyclic systems. |
Novel pentafluorophenyl- and alkoxyphenyl-appended 2,2'-bipyridine push-pull fluorophores: a convenient synthesis and photophysical studies / T. D. Moseev, E. A. Nikiforov, M. V. Varaksin [et al.] // Synthesis. - 2021. - Vol. 53, № 19. - P3597-3607 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): 2,2′-BIPYRIDINES -- 1,2,4-TRIAZINES -- POLYFLUOROARENES Аннотация: A convenient method for the synthesis of new highly in non-polar solvents soluble photoactive pentafluorophenyl-substituted and extended alkoxyphenyl-substituted 2,2′-bipyridines is reported. The synthetic strategy for the preparation of such ligands involves a sequence of several structural transformations, such as O-alkylation, nucleophilic substitution of hydrogen (SN H) in 1,2,4-triazine precursors via the ‘addition–elimination’ scheme, and the subsequent conversion of the obtained 1,2,4-triazines into 2,2′-bipyridines by means of the aza-Diels–Alder reaction. The photophysical properties of the synthesized novel pentafluoroaryl-substituted 2,2′-bipyridines were comprehensively studied. The obtained photophysical data indicate the competitive advantages of the herein reported pentafluoroarylated push–pull fluorophores, bearing extended aliphatic moieties, over their analogues containing benzoxy or phenolic fragments in terms of improvement in quantum yield and well-pronounced positive solvatochromism confirmed by the mathematical analysis according to the Lippert–Mataga equation. |
Coumarin-pyridine push-pull fluorophores: synthesis and photophysical studies / R. F. Fatykhov, A. D. Sharapov, E. S. Starnovskaya [et al.] // Spectrochimica acta part A: molecular and biomolecular spectroscopy. - 2022. - Vol. 267. - Ст. 120499 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: A series of coumarin-pyridine-based push-pull fluorophores were prepared starting from 1,2,4-triazines by using direct C-H functionalization (SNH-reaction)–Diels-Alder–retro Diels-Alder domino reaction sequence. This efficient synthetic strategy allowed to obtain a series of 19 coumarin-pyridine fluorophores. Their photophysical properties were studied. While pyridine-substituted derivatives of 4-alkylcoumarins may be considered as alternative to coumarin dyes characterized by emission maxima mainly in a visible region with wavelengths of 402–415 nm, absorption in the UV range at 210–307 nm, and good photoluminescence quantum yields of 6–19%, all the derivatives of 4-phenylcoumarin did not exhibit any noticeable fluorescence. More detailed photophysical studies were carried out for two the most representative derivatives of 4-alkyl-coumarin-pyridines to demonstrate their positive solvatochromism, and the collected data were analyzed by using Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. The obtained results demonstrate that the combining two chromophore systems, such as 2,5-diarylpyridine and coumarin ones, is promising in terms of improving the photophysical properties of the new coumarin-pyridine hybrid compounds. |
Push–pull derivatives based on 2,4'-biphenylene linker with quinoxaline, [1,2,5]oxadiazolo[3,4-b]pyrazine and [1,2,5]thiadiazolo[3,4-b]pyrazine electron withdrawing parts / E. V. Verbitskiy, Y. A. Kvashnin, G. L. Rusinov [et al.] // Molecules. - 2022. - Vol. 27, № 13. - Ст. 4250 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: A series of novel V-shaped quinoxaline, [1,2,5]oxadiazolo[3,4-b]pyrazine and [1,2,5]thiadiazolo[3,4-b]pyrazine push–pull derivatives with 2,4′-biphenylene linker were designed and their electrochemical, photophysical and nonlinear optical properties were investigated. [1,2,5]Oxadiazolo[3,4-b]pyrazine is the stronger electron-withdrawing fragment as shown by electrochemical, and photophysical data. All compounds are emissive in a solid-state (from the cyan to red region of the spectrum) and quinoxaline derivatives are emissions in DCM solution. It has been found that quinoxaline derivatives demonstrate important solvatochromism and extra-large Stokes shifts, characteristic of twisted intramolecular charge transfer excited state as well as aggregation induced emission. The experimental conclusions have been justified by theoretical (TD-)DFT calculations. |
Conjugates of 8-[2,2’-bipyridinyl]coumarins as potential chemosensors for Al3+, Cu2+, Cd2+, Zn2+ ions: synthesis and photophysical properties / A. D. Sharapov, R. F. Fatykhov, I. A. Khalymbadzha [et al.] // Chimica Techno Acta. - 2023. - Vol. 10, № 4. - P202310417 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): CHEMOSENSORS -- COUMARINS -- 2,2’-BIPYRIDINES Аннотация: In this work, we report the synthesis of novel coumarin-bipyridine conjugates using a sequence of C-C coupling reaction between 5,7-dimethoxycoumarins and 3-pyridyl-6-aryl-1,2,4-triazines followed by the Boger reaction with norbornandiene to obtain 8-[2,2'-bipyridyl]-5,7-dimethoxycoumarins. Photophysical properties were investigated for the obtained series of 8-[2,2'-bipyridyl]-5,7-dimethoxycoumarins: absorption and emission wavelength maxima are in the region of 212-296 and 401-410 nm, respectively; Stokes shifts are up to 116 nm, and fluorescence quantum yields are up to 15.0%. It was found that titrating the conjugates with Al3+, Zn2+, and Cd2+ ions results in an increase in the intensity of the emission maxima of the complexes, while the opposite effect was observed in the case of titration with Cu2+ ions. These findings suggest that the studied compounds may be considered as promising chemosensing materials. Finally, a positive solvatochromism of 8-[2,2'-bipyridyl]coumarins and their metal complexes was established. The experimental data are supported by mathematical calculations according to the Lippert-Matagaequation and Kosower diagram. |