Phenoxazine Derivatives Research Articles

Multi‐Branched Multi‐Anchoring Metal‐Free Dyes for Dye‐Sensitized Solar Cells

AbstractMulti‐branched multi‐anchoring metal‐free dyes as photosensitizers for dye‐sensitized solar cells (DSSCs) are reviewed. The article outlines design strategies, main synthetic routes and optical and photovoltaic properties of two families of multi‐branched sensitizers: (a) D–(π–A)n (D = donor, π = π‐spacer, A = acceptor/anchoring functionality) structures containing arylamine, carbazole, phenothiazine or phenoxazine derivatives as D groups, and (b) multi‐donor multi‐anchoring architectures from interconnected mono‐branched D–π–A arms, together with X‐ and Y‐shaped dyes. Although this class has been reported only in the last five years, a variety of molecular architectures, donors, and π‐spacers have been used and combined in multi‐branched molecules. The multi‐branched geometry induces distinctive features including enhanced qualitative and quantitative optical properties, increased currents and quantum efficiencies, and control of molecular aggregation.

ChemInform Abstract: A Novel Approach for C—C, C—N, and C—O Bond Formation Reactions: A Facile Synthesis of Benzophenazine, Quinoxaline, and Phenoxazine Derivatives via Ring Opening of Benzoxepines.

AbstractApplication of a stoichiometric amount of AcOH instead of a catalytic amount of Bi(OTf)3 affords the corresponding products in similar yields.

Synthesis and Properties of 1,3-Indandione-Disubstituted Derivatives of Carbazole, Phenothiazine, and Phenoxazine

Donor-acceptor type 1,3-indandione derivatives were synthesized and their thermal, optical, photophysical, electrochemical, and photoelectrical properties were studied. They form glasses with the glass transition temperatures ranging from 164 to 249°C. 3,6-di(1,3-indandionyl)-10-methyl-phenothiazine showed the lowest energy emission bands in all the investigated solvents, as well as the largest Stokes shifts. Cyclic voltammograms of the synthesized compounds showed one reversible oxidation couple and quasi-reversible reduction waves. The ionization potentials of the solid samples of the synthesized materials were found to be in the range of 5.52–6.01 eV.

The effect of five-membered heterocyclic bridges and ethoxyphenyl substitution on the performance of phenoxazine-based dye-sensitized solar cells

Phenoxazine derivatives with heterocyclic bridge units and an additional donor were synthesized and applied to dye-sensitized solar cells. To study the effects of these substituents on the DSSC performance, the photophysical, electrochemical, and photovoltaic properties of the dyes were investigated. The introduced heterocyclic bridge units furan and thiophene improved the short-circuit current due to the red-shifted absorption spectra of the dyes. The ethoxyphenyl ring introduced to the phenoxazine moiety as an additional donor broadened the spectrum of the dye, while the reduced adsorption of the dye caused by its non-planar structure limited the enhancement of the short-circuit current. Among the synthesized dyes, the one with furan as a bridge unit showed the best overall conversion efficiency of 5.26%.

A Novel Approach for C–C, C–N, and C–O Bond Formation Reactions: A Facile Synthesis of Benzophenazine, Quinoxaline, and Phenoxazine Derivatives via Ring Opening of Benzoxepines

A new one-pot protocol has been developed for the synthesis of benzophenazine, quinoxaline, and phenoxazine derivatives by the reaction of benzoxepine-4-carboxylates with benzene-1,2-diamines, ethane-1,2-diamine, and 2-aminophenols in the presence of Bi(OTf)3 (5 mol %) under mild conditions in very good yields. The present protocol opens a new way for C-C, C-N, and C-O bond-formation reactions in a single-step process. The structural assignment was confirmed by X-ray analysis.

Reversible Near-Infrared pH Probes Based on Benzo[a]phenoxazine

Several benzo[a]phenoxazine derivatives containing substituted N-aromatic groups are evaluated for their pH-dependent absorption and emission properties. Among the compounds exhibiting optical responses under near-neutral and subacid pH conditions, benzo[a]phenoxazine derivatives with an electron-withdrawing aromatic group attached to nitrogen of the imino group show potential application as near-infrared pH sensors. Three water-soluble pH probes based on benzo[a]phenoxazine with different pyridinium structures are designed and synthesized. Their reversible pH-dependent emissions in buffer solution containing 0.1% dimethyl sulfoxide (DMSO) locate in 625-850 nm with the fluorescent enhancement of 8.2-40.1 times, and their calculated pKa values are 2.7, 5.8, and 7.1, respectively. A composite probe containing the three benzo[a]phenoxazines shows a linear pH-emission relationship in the range of pH 1.9-8.0. Real-time detection of intracellular pH using an in vitro assay with HeLa cells is also reported.

Thermodynamics of Synthesis of New Phenoxazine Derivatives

This article describes a semi-empirical study on the thermodynamics involved in the synthesis of three novel ortho, meta and para, potentially intercalatingphenoxazine 1 derivatives o-(6), m-(7) and p-(8). Quantum chemical calculations at the semi-empirical PM3 method were used in order to evaluate conformational states of the molecules, as well as to predict thermodynamic properties and equilibrium constants. The more favourable product was found to be the compound with the methoxy group in ortho-position. The methoxy group in para-position hinders the reaction by steric factor, which is reflected from the small constant, Kp.

A new phenoxazine derivative isolated from marine sediment actinomycetes, Nocardiopsis sp. 236

During screening of marine actinomycetes for anti-mycobacterial activity, a new phenoxazine derivative (1) was isolated, along with 6-phenazinediol (2), 6-methoxy-1-phenazinol (3), nocardamin (4), and 3-pyridinecarboxylic acid (5), from a culture of Nocardiopsis sp. 236 collected from the west Pacific. The chemical structure of 1 was established on the basis of 1D-, 2D-NMR, and HRQ-TOF MS data. All compounds were evaluated for their anti-mycobacterial activity in vitro, and only compounds 2 and 3 exhibited weak activity.

N-Substituted Phenoxazine and Acridone Derivatives: Structure–Activity Relationships of Potent P2X4 Receptor Antagonists

P2X4 receptor antagonists have potential as drugs for the treatment of neuropathic pain and neurodegenerative diseases. In the present study the discovery of phenoxazine derivatives as potent P2X4 antagonists is described. N-Substituted phenoxazine and related acridone and benzoxazine derivatives were synthesized and optimized with regard to their potency to inhibit ATP-induced calcium influx in 1321N1 astrocytoma cells stably transfected with the human P2X4 receptor. In addition, species selectivity (rat, mouse, human) and receptor subtype selectivity (versus P2X1,2,3,7) were investigated. The most potent P2X4 antagonist of the present series was N-(benzyloxycarbonyl)phenoxazine (26, PSB-12054) with an IC(50) of 0.189 μM and good selectivity versus the other human P2X receptor subtypes. N-(p-Methylphenylsulfonyl)phenoxazine (21, PSB-12062) was identified as a selective P2X4 antagonist that was equally potent in all three species (IC(50): 0.928-1.76 μM). The compounds showed an allosteric mechanism of action. The present study represents the first structure-activity relationship analysis of P2X4 antagonists.

IC‐P‐106: Alzheimer's disease–specific changes in cerebral gray matter revealed using a novel voxel‐wise approach for constructing structural brain networks

ligand.We next performed an in situ competitive binding assay to determine their selective binding affinity for CAA over neuritic plaques in brain tissues of aged Tg2576 mice having both CAA deposits and neuritic plaques. The lipophilicity of phenoxazine derivatives was determined by octanol-water coefficient to predict their brain accessibility. Results: We found that phenoxazine derivatives, in particular 5-5, revealed enhanced binding affinity for CAA as compared with the parental compound. More importantly, synthesized phenoxazine analogs preserved the preferential binding affinity for CAA over neuritic plaques. Conclusions: These results strongly suggest that phenoxazine analogs provide great potential for development of a CAA-specific amyloid tracer that would be a major diagnostic step forward for this frequent (but often under-diagnosed) condition.

ChemInform Abstract: A New Way for Synthesis of Phenoxazine and Diphenoxazine Derivatives via Electrochemical Method.

AbstractThe electrochemical oxidation of hydroquinones (I) and (VI) in the presence of phenols (II) and (IV) as nucleophiles is studied.

Differences in electron densities of phenoxazine and phenothiazine derivatives—charge density studies

High resolution X-ray studies for three single crystals of derivatives of phenoxazine and phenothiazine, 1-(4-phenothiazin-10-yl-phenyl)-ethanone (PAS), 1-(4-phenoxazin-10-yl-phenyl)-ethanone (PAO), and (4-phenoxazin-10-yl-phenyl)phenyl-methanone (PBO), have been carried out and the experimental charge densities for these crystals have been established. A significant intramolecular charge redistribution is observed for the studied moieties. It appears that the donor parts of the molecules studied in all three cases are negatively charged (−0.715, −0.313 and −0.218) and the acceptor fragments carry significant positive charges (0.696, 0.316 and 0.224) for PBO, PAS and PAO, respectively. Separation of the charge between the donor and the acceptor parts in the solid state is in the opposite direction in comparison to the molecules’ behaviour in the solution. Analysis of the geometry of these compounds allowed the explanation of the differences in the values of the electronic coupling element V0. The three most important factors influencing the coupling element are the following: hybridization of the nitrogen atom, conformation of the heterocyclic ring and the torsion angle between the acceptor and the donor parts of the molecules. Theoretical calculations support the charge properties obtained from experiment. The calculated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) indicate that the charge transfer in the excited state takes place from the donor to the acceptor molecular fragments.

On differences in electron densities of phenoxazine and phenothiazine derivatives

phosphonium chloride obtained from single-crystal X-ray diffraction was compared with those obtained from DFT methot in gas phase. The calculated geometric parameters were compared to the corresponding x-ray determination results of the compound. In addition, DFT calculations of the title compound, molecular electrostatic potential and mulliken charge analysis were performed at B3LYP/6-31G(d) level of theory.

Electrochemical synthesis of novel π-extended phenoxazine derivatives of porphyrincatecholes

Three new functionalized phenoxazine-catechol porphyrins 7a–c have been synthesized by a green one-pot method and structurally characterized by spectroscopic analysis. The electro-oxidation of 5,10,15,20-tetrakis(2,3-dihydroxyphenyl) porphyrins( 1a–c) with four catechol units in the presence of 2-aminophenol 8 as bidentate nucleophile has been done and phenoxazine rings have been formed by intermolecular and intramolecular Michael addition reactions. Spectroscopic characterization and voltammetry results have allowed us to propose four independent ECEC mechanisms for the electrochemical oxidation pathway. The functionalization of the porphyrins affected their photophysical properties. Expansion of the UV–vis spectrum range and the decrease of the fluorescence intensity of the products would support the energy transfer between the porphyrin core excited states to the four substitutions as the electron acceptor subunits. SEM images indicate that this method produces regularly shaped manganese porphyrin nano-particles 7c that possess a cubic nano structure.

Synthesis and in vitro antiprotozoal activities of 5-phenyliminobenzo[a]phenoxazine derivatives

A series of 5-phenyliminobenzo[a]phenoxazine derivatives were synthesized. The in vitro antiprotozoal activities were evaluated against Plasmodium falciparum K1, Trypanosoma cruzi, Leishmania donovani and Trypanosoma brucei rhodesiense. N,N-Diethyl-5-((4-methoxyphenyl)imino)-5H-benzo[a]phenoxazin-9-amine shows IC(50)=0.040 μmol L(-1) with a selective index of 1425 against Plasmodium falciparum K1.

Plasmodium berghei proteome changes in response to SSJ-183 treatment

The benzo[ a]phenoxazine derivative, SSJ-183 has shown excellent anti-malarial efficacy and safety. However, its mechanism of action is unclear. We investigated the effect of SSJ-183 on the rodent malarial parasite, Plasmodium berghei. We analyzed changes in protein expression in the erythrocytic cycle of P. berghei with or without 18 h of SSJ-183 treatment by two-dimensional gel electrophoresis. We confirmed results with matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight tandem mass spectrometry. After treatment, seven main proteins were significantly down-regulated, and two were up-regulated; results were reproduced in three independent tests. Some of these proteins were hypothetical parasite proteins or unnamed host products. However, three proteins were identified as a heat shock protein, a disulfide isomerase precursor, and berghepain-2 from P. berghei. All three showed reduced expression after SSJ-183 treatment. This suggested that SSJ-183 was a good anti-malarial drug candidate because it targeted parasite chaperone proteins.

Highly Efficient New Hole Injection Materials for OLEDs Based on Dimeric Phenothiazine and Phenoxazine Derivatives

New hole injection layer (HIL) materials for organic light-emitting diodes (OLEDs) based on phenothiazine and phenoxazine were synthesized, and the electro-optical properties of the synthesized materials were examined by UV−vis and photoluminescence spectroscopy, and by cyclic voltammetry. 10,10′-bis(4-tert-butylphenyl)-N7,N7′-di(naphthalen-1-yl)-N7,N7′-diphenyl-10H,10′H-3,3′-biphenoxazine-7,7′-diamine (1-PNA-BPBPOX) showed glass transition temperatures (Tg) of 161 °C, which was higher than that (110 °C) of Tris(N-(naphthalen-2-yl)-N-phenyl-amino) triphenylamine (2-TNATA), a commercial HIL material. The HOMO levels of the synthesized materials were 4.9−4.8 eV, indicating a good match between the HOMO of indium tin oxide (ITO) (4.8 eV) and the HOMO of N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB) (5.4 eV), a common hole transfer layer (HTL) material. Because the synthesized materials showed minimal absorption at wavelengths shorter than 450 nm, they have good potential for use as effective HIL ...

G-Quadruplex-Binding Benzo[a]phenoxazines Down-Regulate c-KIT Expression in Human Gastric Carcinoma Cells

There is considerable interest in the structure and function of G-quadruplex nucleic acid secondary structures, their cellular functions, and their potential as therapeutic targets. G-Quadruplex sequence motifs are prevalent in gene promoter regions and it has been hypothesized that G-quadruplex structure formation is associated with the transcriptional status of the downstream gene. Using a functional cell-based assay, we have identified two novel G-quadruplex ligands that reduce the transcription of a luciferase reporter driven from the G-quadruplex-containing c-KIT promoter. We have further shown that endogenous c-KIT expression in a human gastric carcinoma cell line is also reduced on treatment with these molecules. Biophysical analysis using surface plasmon resonance has shown that these molecules preferentially bind with high affinity to one of the two G-quadruplex sequences in the c-KIT promoter over double-stranded DNA. This work highlights the utility of cell-based reporter assays to identify new G-quadruplex binding molecules that modulate transcription and identifies benzo[a]phenoxazine derivatives as potential antitumor agents.

A New Way for Synthesis of Phenoxazine and Diphenoxazine Derivatives via Electrochemical Method

Electrochemical oxidation of hydroquinone (1a) and 2,3-dimethylhydroquinone (1b) have been studied in the presence of 2-aminophenol (3a) and 2-amino-4-chlorophenol (3b), as nucleophiles in phosphate buffer solution (pH 7.2) using cyclic voltammetry and controlled potential coulometry. We proposed different mechanisms for the electrode process. The products were derived with good yield and purity using controlled-potential electrochemical oxidation of 1a, b in the presence of 3a and 3b at the graphite electrode in an undivided cell.

ChemInform Abstract: Cyclization of Polyfluorinated 2-Amino and 2-Acetylamino Diaryl Ethers into Phenoxazine Derivatives.

ChemInform Abstract: Cyclization of Polyfluorinated 2-Amino and 2-Acetylamino Diaryl Ethers into Phenoxazine Derivatives.