N-methylphenothiazine Research Articles

High-performance complementary electrochromic device based on surface-confined tungsten oxide and solution-phase N-methyl-phenothiazine with full spectrum absorption

A novel complementary electrochromic device (ECD) with full spectrum absorption, based on surface-confined tungsten oxide (WO3), and solution-phase N-methyl-phenothiazine (NMP) was described and constructed. Cathodically colored inorganic material WO3 is near-infrared active, and anodicallly colored organic material NMP is visible active. These two electrochromic materials possessed the matching redox potential value and complementary spectra absorption in the full spectrum region. The fabricated ECD combined the electrochromic properties of blue colored WO3 and red colored NMP, and exhibited vivid color change from transparent to dark publish-red with superior optical modulation (ΔT %) both in the visible region (81 % at 535 nm) and near-infrared region (70 % at 1000 nm). It took 10 s to color the device under the application of −1.1 V and 18 s to bleach the device completely with the potential of 0 V. Furthermore, the assembled ECD realized a high coloration efficiency of 110 cm2 C−1 at 535 nm and also achieved excellent long-term cycling stability and maintains 95 % of the initial ΔT % value after 60,000 continuous switchings.

Self sensitized photooxidation of N-methyl phenothiazine: acidity control of the competition between electron and energy transfer mechanisms

The reaction pathways following electronic excitation of 10-methyl phenothiazine (MPS) in the presence of oxygen have been investigated as a contribution to establish the mechanisms involved in the phototoxic reactions related to phenothiazine drugs. In the context of previously published results, the pathways of oxidation via the radical cation and/or by reactive oxygen species, such as singlet oxygen and superoxide anion, are of particular interest. The effects of polarity of the medium as well as of proton donors on the different reaction pathways, in particular on the formation of reactive oxygen species and the intermediates of the oxidation of 10-methyl phenothiazine, have been investigated. No reaction was observed in non-polar solvents. In polar solvents, both self-sensitized and sensitized singlet oxygen generation lead to the oxidation of MPS and the production of 10-methyl phenothiazine sulfoxide (MPSO) most probably via a zwitterionic persulfoxide. During self-sensitized photooxidation of MPS in the presence of proton donors, such as carboxylic acids, the zwitterionic intermediate is protonated to the corresponding cation that in turn facilitates the reaction with a second molecule of MPS. In the presence of strong acids however, the formation of the radical cation of MPS and of the superoxide anion, by electron transfer from the triplet excited state of MPS to molecular oxygen, competes efficiently with singlet oxygen formation. In this case, the scavenging of the superoxide anion by protons to yield its conjugated acid (hydroperoxyl radical) and the subsequent disproportionation of the latter prevents back electron transfer.

An Approach for Optimizing the Shell Thickness of Core−Shell Quantum Dots Using Photoinduced Charge Transfer

Photoinduced charge-transfer dynamics between CdSe quantum dots (QDs) possessing varying monolayers of ZnS and hole scavengers such as phenothiazine (PT) and N-methylphenothiazine (NMPT) were investigated for optimizing the shell thickness of core−shell quantum dots. Spectroscopic investigations indicate that phenothiazine binds onto the surface of bare CdSe QDs, resulting in the photoluminescence quenching, and two monolayers of ZnS prevent the electron-transfer process. Methodologies presented here can provide quantitative information on the optimum shell thickness of core−shell QDs, which can suppress the undesired electron transfer and provide maximum luminescence yield.

Synthesis and Characterization of π-Stacked Phenothiazine-Labeled Oligodeoxynucleotides

[reaction: see text] A facile procedure for the incorporation of N-methyl phenothiazine as the terminal nucleoside in oligodeoxynucleotides is reported. The phenothiazine nucleoside analogue is synthesized and then incorporated into DNA using an automated DNA solid-phase synthesizer. Phenothiazine-labeled oligodeoxynucleotides form stable B-form duplexes with higher melting temperatures compared to unlabeled DNA duplexes.

Clusters of Bis- and Tris-Fullerenes

Bis- and tris-fullerene derivatives [bis-(C60) and tris-(C60)] form suspendable clusters in mixed solvents (80% acetonitrile and 20% toluene). These clusters are optically transparent and exhibit interesting nanostructures with sizes ranging from 100 nm to 1 μm and shapes varying from elongated wires to entangled spheres. Ground- and excited-state properties of the clusters of the mono-, bis-, and tris-fullerene derivatives are compared with the corresponding properties of their monomeric forms through steady-state and time-resolved transient absorption spectroscopy. The singlet excited-state quenching of bis- and tris-fullerene derivatives by N-methylphenothiazine (NMP) occurs with rate constants of 5.5 × 109 and 5.3 × 109 M-1 s-1, respectively. The charge separation in these clustered fullerene derivatives is probed by monitoring the formation and decay of the C60 radical anion and the radical cation of NMP. An increase in the number of fullerene moieties in the molecule helps in the formation of ordere...

Study of phenothiazine and N‐methyl phenothiazine by infrared, raman, 1H‐, and 13C‐NMR spectroscopies

AbstractA complete vibrational analysis of the Fourier transform (FT) infrared (IR) and FT‐Raman spectra of both molecules was carried out using quantum chemical calculations. The structure of phenothiazine (PTZ) and N‐methylphenothiazine (N‐MePTZ) were studied by semiempirical, and ab initio methods. Different basis sets and two new procedures for scaling the frequencies of the ring modes were used. Vibrational data of the methyl group in N‐MePTZ were interpreted in terms of the different molecular conformations in the solid state. The 1H‐ and 13C–nuclear magnetic resonance (NMR) data were interpreted in terms of the electron densities on the atoms and the stacking solute–solute association in dimethyl sulfoxide solution. Chemical shifts were related to the Merz‐Kollman atomic charges. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002

Photoinduced ChargeTransfer Polymerization of Acrylonitrile Initiated by N-Substituted Phenothiazines

The polymerization of acrylonitrile (AN) initiated with phenothiazine (PTZ) and its derivatives has been studied. It is found that N-alkyl- substituted phenothiazines possess greater ability to initiate the polymerization of AN under UV irradiation. The initiation mechanism proposed is that the exciplex formed between N-substituted PTZ and AN plays a key role in the initiation process. The kinetic equation for N-methyl phenothiazine (NMP) was determined to be rate of polymerization, Rp = K[NMP]0.46[AN]1.44

Photoinduced Charge-Transfer Polymerization of Acrylonitrile Initiated byN-Substituted Phenothiazines

The polymerization of acrylonitrile (AN) initiated with phenothiazine (PTZ) and its derivatives has been studied. It is found that N-alkyl- substituted phenothiazines possess greater ability to initiate the polymerization of AN under UV irradiation. The initiation mechanism proposed is that the exciplex formed between N-substituted PTZ and AN plays a key role in the initiation process. The kinetic equation for N-methyl phenothiazine (NMP) was determined to be rate of polymerization, Rp = K[NMP]0.46[AN]1.44

Incorporation of sulphonated cyclodextrins into polypyrrole: an approach for the electro-controlled delivering of neutral drugs

The electro-controlled delivery of drugs based on the doping-dedoping mechanism of Electro-Conducting Polymers is restricted to charged substances acting as dopants. In order to overcome this limitation, this study presents an approach where the trapping/delivering is based on host-guest interaction. As an example of a neutral guest, the molecule N-methylphenothiazine (NMP) is encapsulated in the host, heptasulphonated β-cyclodextrin (β-CDSO 3 −), which is tailor-made to dope PPy. The original synthetic method for β-CDSO 3 − is based on sulphonation of the periodated β-CD in the phase transfer medium. As a consequence of their size and of their multicharged character, β-CDSO 3 −s are fixed dopants. The stability of the β-CDSO 3 − entrapment is checked by Optical Beam Deflection (mirage effect) measurements. The ionic movements associated with the switching of the β-CDSO 3 − doped PPy (PPy +, β-CDSO 3 −) film appear to be mainly due to cations with this technique. Cyclic voltammetry experiments confirm the entrapment of neutral NMP by simply dipping the PPy +, β-CDSO 3 − film in a CH 3CN solution containing NMP. Repeated electrochemical cycling of such a reservoir electrode indicates the progressive elimination of NMP from the (PPy +, β-CDSO 3 − [NMP]) film.

Polypyrrole electropolymerization mediated by N-methylphenothiazine: mechanism and immobilization/release kinetics study

Polypyrrole films (PPy) were synthesized in the presence of an electroactive species, N-methylphenothiazine (NMP). Cyclic voltammetric characterization of the monomer and the NMP both in solution revealed the formation of an intermediate species, responsible for the observed catalytic effect on the film growth process. A simple model for the potentiostatic electrosynthesis is proposed with two parallel faradaic processes: the oxidation of the free and of the complexed monomer. This last one is thermodynamically and kinetically favoured compared to the free monomer oxidation. A rotating ring-disc electrode was used to quantify the incorporation of the NMP in the PPy films. A synthesis mechanism is proposed, which takes into account the catalytic effect and an incorporation process which depends on the stability of the intermediate species.

Kinetics and mechanism of oxidation of N-substituted phenothiazines by chromium(VI)

The kinetics of oxidation of N-acetylphenothiazine (NAPT) by Cr(VI) in 80% acetic acid-20% water (v/v) mixture is first-order each in [NAPT] and [Cr(VI)]. The reaction is catalysed by added acid with a third-order dependence in [HCIO4], Increase in polarity of the solvent medium decreases the rate. The oxidation is insensitive to variations in ionic strength as well as added acrylamide. Oxidations of phenothiazine (PT) and N-methylphenothiazine (NMPT) under similar conditions are found to be very fast. However kinetic investigations with NMPT in an acetic acid-sodium acetate buffer show first-order dependence each in [NMPT] and [Cr(VI)] and a fractional-order dependence in [H+] in the pH range 1.80-3.09. Increase in polarity of the medium increases the rate. In both the cases, the corresponding sulphoxides are identified as oxidation products. Based on the kinetic results, mechanisms for oxidations are proposed.

Determination of Caffeine in Human Plasma and Urine by Gas Chromatography Using a Nitrogen Phosphorus-Detector

A simple method for the determination of caffeine (1, 3, 7-trimethylxanthine) in plasma and urine is described. Caffeine was extracted by diethyl ether, together with spiked N-methylphenothiazine (NMPZ) as an internal standard. The amount was measured with gas chromatography (GC) using a nitrogen phosphorus-detector (NP-D). Almost 96% of the caffeine was recovered by diethyl ether. The detection limits of this assay were 1ng/ml of both in plasma and urine. Moreover, good linear relationships between peak height ratios and the concentrations of caffeine were found in the range 0 to 10μg/ml of plasma and 0 to 40μg/ml of urine, and reproducibility was kept within 3%. This method is rapid, sensitive and suitable as a routine method in the clinic.