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1.
Anal Chem ; 93(41): 13835-13843, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34623138

RESUMO

The chemical derivatization of multiple lipid classes was developed using benzoyl chloride as a nonhazardous derivatization agent at ambient conditions. The derivatization procedure was optimized with standards for 4 nonpolar and 8 polar lipid classes and measured by reversed-phase ultrahigh-performance liquid chromatography-tandem mass spectrometry. The derivatization and nonderivatization approaches were compared on the basis of the calibration curves of 22 internal standards from 12 lipid classes. The new method decreased the limit of detection 9-fold for monoacylglycerols (0.9-1.0 nmol/mL), 6.5-fold for sphingoid base (0.2 nmol/mL), and 3-fold for diacylglycerols (0.9 nmol/mL). The sensitivity expressed by the ratio of calibration slopes was increased 2- to 10-fold for almost all investigated lipid classes and even more than 100-fold for monoacylglycerols. Moreover, the benzoylation reaction produces a more stable derivative of cholesterol in comparison to the easily in-source fragmented nonderivatized form and enabled the detection of fatty acids in a positive ion mode, which does not require polarity switching as for the nonderivatized form. The intralaboratory comparison with an additional operator without previous derivatization experiences shows the simplicity, robustness, and reproducibility. The stability of the derivatives was determined by periodical measurements during a one month period and five freeze/thaw cycles. The fully optimized derivatization method was applied to human plasma, which allows the detection of 169 lipid species from 11 lipid classes using the high confidence level of identification in reversed-phase (RP)-ultra high performance liquid chromatography (UHPLC)/mass spectrometry (MS). Generally, we detected more lipid species for monoacylglycerols, diacylglycerols, and sphingoid bases in comparison with previously reported papers without the derivatization.


Assuntos
Lipídeos , Espectrometria de Massas em Tandem , Benzoatos , Cromatografia Líquida de Alta Pressão , Humanos , Reprodutibilidade dos Testes
2.
J Org Chem ; 86(21): 14663-14671, 2021 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-34648709

RESUMO

A Y-shaped push-pull dye (1) with N,N-dimethylanilino donors and a benzonitrile acceptor connected via an imidazole-based π-conjugated spacer was designed. It showed a dark yellow color in solution due to facile intramolecular charge-transfer interaction, but no fluorescence was detected, presumably due to the photo-induced electron transfer effect of the imidazole moiety. However, addition of nerve agents such as diethyl chlorophosphate (DCP, sarin mimic) and diethyl cyanophosphate (DCNP, Tabun mimic) resulted in a blue-colored fluorescence with fading of the native dark yellow color. Mechanistic studies indicated nucleophilic attack of imidazole at the phosphorus of DCP or DCNP, leading to the formation of a phosphorylated intermediate, which undergoes time-dependent hydrolysis (∼24 h) in aqueous medium. This process recovers the free probe (enzyme-like behavior) and releases a less-toxic organophosphate compound as the byproduct. The phosphorylated derivative of 1, formed during such interaction, shows a different electronic behavior, which reduces the extent of charge-transfer interaction as well as nonradiative decay and supports emissive properties. Considering the high sensitivity of 1 towards DCP and DCNP with LOD 35 and 42 ppb, we prepared easy test strips for on-site vapor-phase detection of nerve agents.

3.
Org Biomol Chem ; 19(40): 8830-8839, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34554164

RESUMO

Inspired by the successful utilization of aziniums as anolytes in redox-flow batteries, we have designed and prepared a systematically extended series of (di)azinium compounds based on pyrazine, bipyridine, 1,5-naphthyridine, 3,8-phenanthroline, (E)-4,4'-diazastilbene and 1,2-bis(pyridin-4-yl)acetylene. It has been revealed that the fundamental electrochemical properties are affected mostly by the water-solubility and chemical stability of the particular redox forms. Based on the systematically evolved azinium structure and gathered electrochemical data, structure-property relationships were thoroughly elucidated. Further investigation on flow battery cells identified that the known 4,4'-bipyridinium decorated with two peripheral N-propyl-3-sulfonato pendants allows utilizing both redox steps with good cycling stability, while the naphthyridine scaffold turned out to be a new and promising scaffold for redox-flow batteries.

4.
Chempluschem ; 86(5): 758-762, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33973733

RESUMO

A series of four V-shaped methylpyrimidinium salts bearing diphenylamino-electron-donating groups appended at various pyrimidine positions were designed. These chromophores were obtained by regioselective N(1) monomethylation by methyl methanesulfonate of the pyrimidine core. Linear optical properties were studied experimentally and electronic properties were further completed by (TD)-DFT calculations. The second-order nonlinear optical (NLO) properties were also studied using electric field induced second harmonic generation (EFISH) method in chloroform, and all pyrimidinium salts exhibited µß0 >1000×10-48  esu. The 2,4-disubstituted pyrimidinium core is preferred over 4,6-disubstitution as it enhances the NLO response and increases the dipole moment. (E,E)-2,4-Bis[4-(diphenylamino)styryl]-1-methylpyrimidin-1-ium methanesulfonate appears to be the best NLO-phore in chloroform in the series (µß0 =2500×10-48  esu) and a figure of merit µß0 /MW=3.4 10-48  esu mol g-1 .

5.
ACS Omega ; 6(10): 6554-6558, 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33748567

RESUMO

Organoselenium compounds with perspective application as Se precursors for atomic layer deposition have been reviewed. The originally limited portfolio of available Se precursors such as H2Se and diethyl(di)selenide has recently been extended by bis(trialkylsilyl)selenides, bis(trialkylstannyl)selenides, cyclic selenides, and tetrakis(N,N-dimethyldithiocarbamate)selenium. Their structural aspects, property tuning, fundamental properties, and preparations are discussed. It turned out that symmetric four- and six-membered cyclic silyl selenides possess well-balanced reactivity/stability, facile and cost-effective synthesis starting from inexpensive and readily available chlorosilanes, improved resistance toward air and moisture, easy handling, sufficient volatility, thermal resistance, and complete gas-to-solid phase exchange reaction with MoCl5, affording MoSe2 nanostructures. These properties make them the most promising Se precursor developed for atomic layer deposition so far.

6.
Chemistry ; 27(3): 1145-1159, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33016475

RESUMO

Six pyrimidine-based push-pull systems substituted at positions C2 and C4/6 with phenylacridan and styryl moieties, employing methoxy or N,N-diphenylamino donors, have been designed and synthesized through cross-coupling and Knoevenagel reactions. X-ray analysis confirmed that the molecular structure featured the acridan moiety arranged perpendicularly to the residual π system. Photophysical studies revealed significant differences between the methoxy and N,N-diphenylamino chromophores. Solvatochromic studies revealed that the methoxy derivatives showed dual emission in polar solvents. Time-resolved spectroscopy revealed that the higher energy band involved very fast (<80 ps) fluorescence, whereas the lower energy one included long components (≈30 ns) due to long-lived intramolecular charge-transfer fluorescence. In contrast to N,N-diphenylamino chromophores, the methoxy derivatives also showed aggregation-induced emission in mixtures of THF/water, as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates not far from that of pure white light. These properties render the methoxy derivatives as very promising organic materials for white organic light-emitting diodes.

7.
Molecules ; 25(21)2020 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-33182429

RESUMO

The current portfolio of organoselenium compounds applicable as volatile precursors for atomic layer deposition can be denoted as very limited. Hence, we report herein facile and cost-effective preparation of two bis(trialkylstannyl)selenides as well as one selenole and three bis(trialkylsilyl)selenides. Their syntheses have been optimized to: (i) use readily available and inexpensive starting materials, (ii) involve operationally simple methodology (heating in a pressure vessel), (iii) use a minimum amount of additives and catalysts, and (iv) either exclude additional purification or involve only simple distillation. The chemical structure of prepared Se derivatives was confirmed by multinuclear NMR and GC/MS. Their fundamental thermal properties were investigated by differential scanning calorimetry (DSC) and TGA methods that revealed thermal stability within the range of 160-300 °C.


Assuntos
Técnicas de Química Sintética/economia , Compostos Organosselênicos/síntese química , Compostos Orgânicos Voláteis/síntese química , Varredura Diferencial de Calorimetria , Catálise , Análise Custo-Benefício , Cromatografia Gasosa-Espectrometria de Massas , Chumbo/química , Espectroscopia de Ressonância Magnética , Compostos Organosselênicos/química , Oxigênio/química , Temperatura , Termogravimetria
8.
Chempluschem ; 85(7): 1549-1558, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32706173

RESUMO

A series of new push-pull chromophores based on a combined cyclopenta[c]thiophene-4,6-dione (ThDione) acceptor, N,N-dimethylaniline, N-piperidinylthiophene or ferrocene donors, and ethylene or buta-1,3-dienylene π-linkers has been designed and synthesized. Utilizing one or two ThDione acceptors afforded linear or branched push-pull molecules. Experimental and theoretical study of their fundamental properties revealed thermal robustness up to 260 °C, a electrochemical/optical HOMO-LUMO gap that is tunable within the range of 1.47-2.19/1.99-2.39 eV, and thorough elucidation of structure-property relationships. Compared to currently available portfolio of heterocyclic electron-withdrawing units, ThDione proved to be a powerful and versatile acceptor unit. It imparts significant intramolecular charge transfer and polarizes the π-system, which results in enhanced (non)linear optical response.

9.
Chempluschem ; 85(3): 576-579, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32202391

RESUMO

Three cyclic silylselenides were prepared in a straightforward manner. Property tuning has been achieved by varying the ring size and the number of embedded selenium atoms. All silylselenides possess improved resistance towards moisture and oxidation as well as high thermal robustness and sufficient volatility with almost zero residues. The six-membered diselenide proved to be particularly superior Se precursors for atomic layer deposition and allowed facile preparation of MoSe2 layers. Their structure and composition have been investigated by Raman and X-ray photoelectron spectroscopy as well as scanning electron microscopy revealing vertically aligned flaky shaped nanosheets.

10.
Phys Chem Chem Phys ; 22(7): 4165-4176, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-32040113

RESUMO

This contribution aims at investigating the branching effect on the steady state, time resolved fluorescence and two-photon absorption (2PA) properties of dimethylamino and diphenylamino substituted styrylpyrimidine derivatives, by means of a combined experimental and theoretical study. In contrast to classical branched molecules with a triphenylamine central core and electron accepting groups at the periphery, here, branched molecules with reverse topology and different symmetries are examined, namely a styrylpyrimidine group is used as the electron withdrawing core and dimethylamino or diphenylamino donors are incorporated at the periphery. Besides, compared to the great majority of existing branched systems, the herein studied molecules do not have C3 symmetry. For this reason, the region of the linear and non-linear optical spectra of the two and three branched chromophores is actually similar. Interestingly, while the one-photon absorption spectra of one-branched systems versus two- or three-branched ones are spectrally shifted, there is almost no spectral shift in the main 2PA spectral region. Meanwhile, there is still an enhancement of both linear and nonlinear optical responses. Overall, here we developed a strategy that enhances the 2PA response while maintaining the spectral position. Specifically, 2PA cross section values as high as 500 GM have been obtained for the diphenylamino A-(π-D)3 molecule in dichloromethane.

11.
J Comput Aided Mol Des ; 34(6): 683-695, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32052351

RESUMO

Classical molecular simulation methods were used for a description of an arrangement of intercalated molecules N-(pyridin-4-yl)pyridin-4-amine (AH) and its derivatives, 3-methyl-N-(pyridin-4-yl)pyridin-4-amine (AMe), and 3-nitro-N-(pyridin-4-yl)pyridin-4-amine (ANO2) within a layered structure of zirconium 4-sulfophenylphosphonate. The intercalated molecules were placed between SO3H groups of the host layers. Their mutual positions and orientations were solved by molecular simulation methods and compared with the presented experimental results. Final calculated data showed differences of partially disordered arrangement of the intercalated molecules between zirconium 4-sulfophenylphosphonate layers. The calculation results revealed a dense net of hydrogen bonds connecting water molecules and the guests in the interlayer space and the sulfo groups of the host layers. We calculated the dipole moments of the AH, AMe and ANO2 guests in the final models in order to illustrate potential use of these materials in non-linear optics.


Assuntos
Aminas/química , Modelos Moleculares , Piridinas/química , Simulação por Computador , Ligação de Hidrogênio , Estrutura Molecular , Zircônio/química
12.
Chem Rec ; 20(5): 440-451, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31638743

RESUMO

Conjugated push-pull molecules that incorporate nitrogen heterocycles as electron-withdrawing units are interesting materials because of their luminescence properties. These chromophores can be easily and reversibly protonated at the nitrogen atom of the heterocyclic ring and this can cause dramatic color changes. White and multi-color photoluminescence both in solution and in the solid state can be obtained by an accurate control of the amount of acid. Thus, with a suitable design these compounds have potential applications in the development of colorimetric pH sensors and the fabrication of OLEDs based on only one material. We provide here a brief overview of our collaborative efforts made in this area.

13.
Front Chem ; 8: 631477, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33732685

RESUMO

Bipyridinium salts are currently very popular due to their perspective applications in redox flow batteries. Hence, we designed and prepared a series of bipyridiniums based on 2,2'-, 3,3'-, and 4,4'-bipyridine and 2,2'-bipyrimidine. The straightforward synthesis utilizes commercially or readily available starting compounds and their direct N-alkylation, mostly using 1,3-propanesultone. All eleven target derivatives with systematically evolved structure were investigated by cyclic voltammetry, which allowed elucidating thorough structure-property relationships. The electrochemical behavior depends primarily on the parent scaffold, type of N-alkylation, number of quaternized nitrogen atoms, planarity, counter ion as well as the used media. Two derivatives featuring quasi-reversible redox processes were further tested on rotating disc electrode and in a flow battery half-cell. 4,4'-Bipyridinium derivative bearing two sultone residues showed better performance and stability in the flow half-cell with small capacity decays of 0.09/0.15% per reduction-oxidation cycle, based on the number of the utilized redox processes (one/two).

14.
Top Curr Chem (Cham) ; 377(3): 14, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31062103

RESUMO

Quaternary ammonium compounds, referred to as QACs, are cationic substances with a structure on the edge of organic and inorganic chemistry and unique physicochemical properties. The purpose of the present work is to introduce QACs and their wide application potential. Fundamental properties, methods of preparation, and utilization in organic synthesis are reviewed. Modern applications and the use of QACs as reactive substrates, reagents, phase-transfer catalysts, ionic liquids, electrolytes, frameworks, surfactants, herbicides, and antimicrobials are further covered. A brief discussion of the health and environmental impact of QACs is also provided. The emphasis is largely on tetraalkylammonium compounds bearing linear alkyl chains.


Assuntos
Anti-Infecciosos/química , Herbicidas/química , Compostos de Amônio Quaternário/química , Tensoativos/química , Anti-Infecciosos/síntese química , Anti-Infecciosos/farmacologia , Herbicidas/síntese química , Herbicidas/farmacologia , Compostos de Amônio Quaternário/síntese química , Compostos de Amônio Quaternário/farmacologia , Tensoativos/síntese química , Tensoativos/farmacologia
15.
Org Biomol Chem ; 17(14): 3623-3634, 2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30916108

RESUMO

Fourteen new D-π-A push-pull chromophores based on two isomeric thienothiophene donors and seven acceptors of various electronic natures have been designed and conveniently synthesized. In contrast to known thienothiophene push-pull molecules, the prepared small chromophores proved to be organic materials with easily tunable thermal, electrochemical and (non)linear optical properties. It has also been shown that small structural variation may result in significantly improved/varied fundamental properties. Very detailed structure-property relationships were elucidated within the systematically developed series of push-pull molecules, which may serve as a useful guide in designing new D-π-A molecules based on fused thiophene scaffolds.

16.
J Org Chem ; 84(4): 1787-1796, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30596244

RESUMO

An easy-to-synthesize, biimidazole push-pull dye has been designed, comprising two mutually independent analyte binding sites. It has been found that Hg2+ coordinates with the compound via thiophene residue and inhibits the charge-transfer (CT) process, which transforms the yellow-colored solution colorless. On the other hand, an unusually large bathochromic shift is observed in CT band upon addition of Cu2+, accompanied by a change in the color from yellow to red. A rather surprising observation is made from mechanistic studies, where it indicates that Cu2+ catalyzes the formation of 6-imino-5,6-dihydropyrrolo[3,4- d]imidazole-4(3 H)-one (IPIMO) derivative. This strongly affects the charge-transfer state of the compound as well as its polarizability. Most importantly, this is the first report where IPIMO formation reaction has been exploited for sensing of a metal ion. Further, the system was employed for screening of both of these metal ions in wastewater samples. Recovery values ranging from 93.3 to 105.0% confirm the suitability of the present method for estimating trace level of metal ions in complex matrices. In addition, inexpensive on-site detection systems were developed using paper strips.

17.
J Phys Chem A ; 123(2): 417-428, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30365895

RESUMO

A comparative study of the photophysical properties of octupolar pyridyl-terminated triphenylamine molecule, with its quadrupolar and dipolar analogues, by means of ambient and low temperature steady state spectroscopy and femtosecond to nanosecond time-resolved fluorescence spectroscopy is reported. The push-pull molecules bear triphenylamine electron donating core, pyridine peripheral electron acceptors, and acetylene π-bridge. The samples were studied in solvents of varying polarity and also upon addition of small amounts of acetic acid to induce protonation of the pyridine group. All samples exhibit significant positive fluorescence solvatochromism as well as a relaxation of their excited state to a solvent relaxed intramolecular charge transfer state on the picosecond time scale. For the octupolar compound, excited state relaxation occurs simultaneously with excitation energy hopping among the branches. The hopping time is solvent polarity controlled since it becomes slower as the polarity increases. The experimental hopping times are compared to those predicted by Förster and Fermi formulations. The samples are capable of emitting broadband light covering almost the whole visible spectrum by careful control of protonation. Energy transfer from the neutral toward the protonated species on the 1 ps time scale is revealed.

18.
J Org Chem ; 83(19): 11712-11726, 2018 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-30178669

RESUMO

The synthesis of a series of 20 new 2,4,6-tristyrylpyrimidines and three new 2,4-distyrylpyrimidines by means of combination of Knoevenagel condensation and Suzuki-Miyaura cross-coupling reaction is reported. This methodology enables us to obtain chromophores with identical or different substituent on each arm. The photophysical properties of the compounds are described. Optical properties and time-dependent density functional theory calculations indicate that photophysical properties of target compounds are mainly affected by the nature of the electron-donating group in C4/C6 positions, except when the C2 substituent is a significantly stronger electron-donating group. However, the C2 substituent has a strong influence on emission quantum yield: addition of a strong electron-donating group tends to decrease the fluorescence quantum yield, whereas a moderate electron-withdrawing group results in a significant increase of fluorescence quantum yield.

19.
Beilstein J Org Chem ; 13: 2374-2384, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29181118

RESUMO

Nine new quadrupolar chromophores based on diketopyrrolopyrrole were designed and prepared by cross-coupling reactions. The property tuning has been achieved by structural variation of the peripheral substituents (donor) and enlargement of the π-system. Fundamental properties of target molecules were studied by differential scanning calorimetry, electrochemistry, and absorption and emission spectra. Nonlinear optical properties were studied by measuring the third harmonic generation. The experimental data were completed by quantum-chemical calculations and structure-property relationships were elucidated.

20.
Chem Cent J ; 11(1): 31, 2017 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-29086832

RESUMO

BACKGROUND: A series of rare-earth bisphthalocyanines of praseodymium, samarium and gadolinium bearing 5-bromo-2-thienyl substituents were prepared for the first time. RESULTS: Three bis[octakis(5-bromo-2-thienyl)] rare-earth metal(III) bisphthalocyanine complexes (Pr, Sm, Gd) were synthesized for the first time. The new compounds were characterized by UV-vis, NIR, FT-IR, mass spectroscopy and thermogravimetry as well as elementary analysis and electrochemistry. Production of singlet oxygen was also estimated using 9,10-dimethylanthracene method. CONCLUSIONS: The bromine substituent causes significant changes in molecule paramagnetism, singlet oxygen production, HOMO position and spectral characteristics. The compounds in solutions exist in two forms (neutral and/or reduced) depending on the solvent and rare-earth metal. Moreover, the compounds exhibit much increased stability under acid conditions compared with non-brominated derivatives. Graphical abstract Prepared compounds for the study of their chemical and other properties.

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