86-28-2Relevant articles and documents
Push-pull fluorophores with viscosity dependent and aggregation induced emissions insensitive to polarity
Telore, Rahul D.,Satam, Manjaree A.,Sekar, Nagaiyan
, p. 359 - 367 (2015)
Abstract A series of push-pull chromophoric extended styryls from 5,5′-(9-ethyl-9H-carbazole-3,6-diyl)bis(2-morpholinothiazole-4-carbaldehyde) were synthesized by Knoevenagal condensation reaction with active methylene compounds. The intermediate carbaldehyde was synthesized from carbazole through multistep reactions. The intramolecular charge transfer of synthesized highly conjugated symmetrical D-π-A (D-donor, A-acceptor) extended styryls with rigid structure have been investigated by means of photophysical properties. The photophysical properties like absorption, emission and quantum yield of styryl derivatives were evaluated in various solvents of different polarities. All these synthesized extended styryls have exhibited aggregation induced emission with enhanced fluorescence intensity. This series of compounds can also be used as fluorescence molecular rotors for viscosity sensing. The sensitivity of viscosity towards UV absorption as well as fluorescence emission has also been investigated.
Fluorescence Quenching Mechanism of Aromatic Hydrocarbons by Closed-Shell Heavy Metal Ions in Aqueous and Organic Solutions
Masuhara, Hiroshi,Shioyama, Hiroshi,Saito, Tokashi,Hamada, Kei,Yasoshima, Seikichi,Mataga, Noboru
, p. 5868 - 5873 (1984)
Fluorescence quenching rate constants of some aromatic hydrocarbons by Zn2+, Ag+, Cd2+, In3+, Sn2+, Cs+, Hg2+, Tl+, and Pb2+ were determined in aqueous and N,N-dimethylformamide solutions.Paramagnetic interactions, the heavy atom effect, and electron transfer were excluded as a possible quenching mechanism.N2 gas laser photolysis studies revealed that a cation radical of the fluorescer was detected only N-ethylcarbazole quenched by Ag+, Pb2+, and Hg2+ in N,N-dimethylformamide and for 1-pyrenesulfonic acid by Hg2+ in water.All other systems yielded the triplet state of the fluorescer quantitatively.The intermediates observed in the microsecond time region are the transient species with the lowest free energy.Picosecond laser photolysis of the Ag+ and Pb2+ quencher systems in N,N-dimethylformamide confirmed directly that the triplet state is induced by fluorescence quenching.On the basis of these results, it has been concluded that fluorescence quenching is due to nonfluorescent complex formation followed by rapid intersystem crossing.The electronic and geometrical structures of this complex were considered and compared to the excited aromatic hydrocarbon-halogen anion systems.
Fabrication of Eu(III) complex doped nanofibrous membranes and their oxygen-sensing properties
Songzhu, Lin,Xiangting, Dong,Jinxian, Wang,Guixia, Liu,Wenshen, Yu,Ruokun, Jia
, p. 885 - 889 (2010)
In this paper, we report the synthesis, characterization, and photophysical properties of Eu(TTA)3ECIP, where TTA = 2-thenoyltrifluoroacetonate, and ECIP = 1-ethyl-2-(N-ethyl-carbazole-yl-4-)imidazo[4,5-f]1,10- phenanthroline. Its elementary application for oxygen-sensing application is also investigated by doping it into a polymer matrix of polystyrene (PS). Experimental data suggest that the 2.5 wt% doped Eu(TTA)3ECIP/PS nanofibrous membrane exhibits a high sensitivity of 3.4 towards oxygen with a good linear relationship of R2 = 0.9962. In addition, the 2.5 wt% doped Eu(TTA)3ECIP/PS nanofibrous membrane owns a quick response of 8 s towards oxygen, along with its excellent atmosphere insensitivity and photobleaching resistance. All these results suggest that both Eu(TTA) 3ECIP and Eu(TTA)3ECIP/PS system are promising candidates for oxygen-sensing optical sensors.
NLOphoric 3,6-di(substituted quinoxalin) Carbazoles – Synthesis, Photophysical Properties and DFT Studies
Telore, Rahul D.,Jadhav, Amol G.,Sekar, Nagaiyan
, p. 1531 - 1540 (2017)
Synthesis of novel 3,6-di(substituted quinoxalin) carbazole fluorophores by the condensation of 1,1′-(9-ethyl-9H-carbazole-3,6-diyl)bis(2-bromoethanone) with methyl, chloro and unsubstituted o-phenylenediamine is presented. Synthesized derivatives are well characterized by 1H NMR, 13C NMR, FTIR and Mass spectroscopy. Photophysical studies are carried out using solvents of varying polarities revealed positive solvatochromism and intramolecular charge transfer from carbazole (Donor) to quinoxalin (Acceptor). Intramolecular charge transfer properties are correlated by dipole moment changes and different polarity functions like Lippert–Mataga, Bilot-Kawski, Bakhshiev and Liptay plots with very good regression factors. Mulliken hush-analysis further support charge transfer characteristic. Linear and Nonlinear optical properties are explained by solvatochromic data using two-level quantum mechanical model and are correlated with computational calculations using density functional theory at B3LYP/6-31G(d) level. First hyperpolarizability value of all the synthesized compounds is found to be greater than urea by >333 times. Moreover, increase of hyperpolarizability values from non-polar to polar solvents are in good correlation with the significant charge transfer characteristic in polar solvents.
Comparing Separation vs. Fresh Start to Assess Reusability of Pd/C Catalyst in Liquid-Phase Hydrogenation
Mironenko, Roman M.,Saybulina, Elina R.,Trenikhin, Mikhail V.,Izmailov, Rinat R.,Lotsman, Kristina A.,Rodygin, Konstantin S.,Ananikov, Valentine P.
, p. 3656 - 3661 (2021/07/02)
The reusability of metal catalysts is a key issue for the potential application of new catalysts in research and industrial practice. The most common procedure for testing catalyst reusability in liquid-phase heterogeneous reactions is based on separating a catalyst from a reaction mixture followed by the next run. An alternative procedure called “fresh start” consists of the addition of a new portion of reagents to the reaction mixture without any isolation operation. In this work, we compare both procedures in a model Pd/C-catalyzed hydrogenation with different heteroatoms, e. g., O-, S-, and N-vinyl derivatives. It was shown that regardless of whether the catalyst is stable or potentially poisoned during the reaction, both procedures lead to comparable results. It appears that a much easier implementation of a fresh start procedure may be an option of choice. The possibilities of using both procedures to rationalize the experimental protocol for assessing Pd/C catalyst reusability in liquid-phase hydrogenations are discussed.
Synthesis method of N-ethyl carbazole
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Paragraph 0026-0028, (2021/01/25)
The invention discloses a synthesis method of N-ethyl carbazole, and belongs to the technical field of organic synthesis. The method comprises the following steps: (1) adding anhydrous acetonitrile, sodium and carbazole into a high-pressure reactor, introducing ethylene to replace air, continuously introducing ethylene until the pressure is 45 MPa, heating to 80-150 DEG C, carrying out a reactionat a constant temperature for 3-10 hours, and replacing gas in the high-pressure reactor with nitrogen after the reaction is finished; wherein the dosage of sodium is 0.5-2.0% of the mass of carbazole; and (2) after the reaction is finished, distilling the reaction liquid under normal pressure at the temperature of 80-90 DEG C, stopping distilling until the volume is 40-60%, recovering the distilled solvent, cooling to 68-80 DEG C, filtering when the solution is still hot, finally, carrying out reduced pressure distillation at the temperature of 90-110 DEG C under the vacuum degree of less than 1 mmHg, and drying to obtain N-ethyl carbazole. The method has the advantages of simple process, recyclable solvent, high yield, high purity and the like.
A general strategy to increase emission shift of two-photon ratiometric pH probes using a reversible intramolecular reaction of spiro-oxazolidine
He, Xiuquan,Tian, Minggang,Yang, Rui,Yu, Xiaoqiang,Zhang, Huamiao
supporting information, (2020/10/18)
Fluorescent pH probes have been served as powerful tools in biological and pathological studies in recent years due to the important roles of pH values in various physiological processes. Although plenty of pH probes have been delivered, development of two-photon ratiometric pH probes with large emission shift for detecting the variation of intracellular pH values is still a greatly challenging task. To address this concern, in this work, we have discovered a general strategy designing pH probes by means of a pH-dependent reversible intramolecular reaction of spiro-oxazolidine which can efficiently change their conjugation length and the electronic effect concurrently. To display the generality of the strategy, we have synthesized six pH probes, and all these probes exhibit short emission in basic conditions and dramatically red-shifted emission in acid environments. The emission shift of the six probes is more than 150 nm and even up to 210 nm, much larger than shift of all commercial and reported pH probes. The chemical sensing mechanism of intramolecular ring opening/closing reaction of spiro-oxazolidine has been confirmed with 1H NMR spectra and density functional theory (DFT) calculations. Finally, we have used one of six with one- and two-photon properties to successfully image lysosomal pH changes under confocal and two-photon microscopes in a ratiometric manner. We believed that this spiro-oxazolidine strategy can serve as a general and powerful platform for the design of ideal pH probes.
