A simple method to prepare highly ordered PS-b-P4VP block copolymer template

A control strategy for tuning the film morphology of asymmetric polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymers (BCPs) is reported. After preparation of the film by spin-coating method, the as-cast films were annealed in different solvent vapor. It is found that chloroform is a wonderful solvent for forming PS-b-P4VP regular pattern. Otherwise, with changing the concentration of PS-b-P4VP, cylindrical or parallel nanostructures could be attained. The PS-b-P4VP films with cylindrical structure are used as template to deposit FePt nanoparticles into the pores. Nanoparticles reaching the bottom of the holes form a disordered magnetic array.     

Application of N-PLS calibration to the simultaneous determination of Cu(2+), Cd(2+) and Pb(2+) using peptide modified electrochemical sensors

The simultaneous determination of Cu(2+), Cd(2+) and Pb(2+) is demonstrated at four modified gold electrodes using N-PLS calibration. Three of the electrodes were modified with the peptides Gly-Gly-His, gamma-Glu-Cys Gly and human angiotensin I which were covalently attached to thioctic acid self-assembled monolayers and the fourth electrode was modified with thioctic acid only. Voltammetry at the modified electrodes in the presence of the three metal ions revealed one peak due to the reduction of copper and another due to the overlapping peaks of cadmium and lead which made quantification using conventional methods difficult. N-PLS was used to calibrate and predict trace concentrations (100 nM to 10 microM) of mixtures of Cu(2+), Cd(2+) and Pb(2+).     

Luminescent Pincer Platinum(II) Complexes with Emission Quantum Yields up to Almost Unity: Photophysics,Photoreductive C?C Bond Formation,and Materials Applications

Luminescent pincer‐type Pt^II complexes supported by C‐deprotonated π‐extended tridentate R C^N^N R′ ligands and pentafluorophenylacetylide ligands show emission quantum yields up to almost unity. Femtosecond time‐resolved fluorescence measurements and time‐dependent DFT calculations together reveal the dependence of excited‐state structural distortions of [Pt(R C^N^N R′)(CC‐C₆F₅)] on the positional isomers of the tridentate ligand. Pt complexes [Pt(R‐C^N^N R′)(CC‐Ar)] are efficient photocatalysts for visible‐light‐induced reductive C C bond formation. The [Pt(R‐C^N^N R′)(CC‐C₆F₅)] complexes perform strongly as phosphorescent dopants for green‐ and red‐emitting organic light‐emitting diodes (OLEDs) with external quantum efficiency values over 22.1 %. These complexes are also applied in two‐photon cellular imaging when incorporated into mesoporous silica nanoparticles (MSNs).     

A Theoretical Investigation into the Luminescent Properties of d8‐Transition‐Metal Complexes with Tetradentate Schiff Base Ligands

A theoretical investigation on the luminescence efficiency of a series of d⁸ transition‐metal Schiff base complexes was undertaken. The aim was to understand the different photophysics of [M‐salen]ⁿ complexes (salen=N,N′‐bis(salicylidene)ethylenediamine; M=Pt, Pd (n=0); Au (n=+1)) in acetonitrile solutions at room temperature: [Pt‐salen] is phosphorescent and [Au‐salen]⁺ is fluorescent, but [Pd‐salen] is nonemissive. Based on the calculation results, it was proposed that incorporation of electron‐withdrawing groups at the 4‐position of the Schiff base ligand should widen the ³MLCT–³MC gap (MLCT=metal‐to‐ligand charge transfer and MC=metal centered, that is, the dd excited state); thus permitting phosphorescence of the corresponding Pd^II Schiff base complex. Although it is experimentally proven that [Pd‐salph‐4E] (salph=N,N′‐bis(salicylidene)‐1,2‐phenylenediamine; 4E means an electron‐withdrawing substituent at the 4‐position of the salicylidene) displays triplet emission, its quantum yield is low at room temperature. The corresponding Pt^II Schiff base complex, [Pt‐salph‐4E], is also much less emissive than the unsubstituted analogue, [Pt‐salph]. Thus, a detailed theoretical analysis of how the substituent and central metal affected the photophysics of [M‐salph‐X] (X is a substituent on the salph ligand, M=Pt or Pd) was performed. Temperature effects were also investigated. The simple energy gap law underestimated the nonradiative decay rates and was insufficient to account for the temperature dependence of the nonradiative decay rates of the complexes studied herein. On the other hand, the present analysis demonstrates that inclusions of low‐frequency modes and the associated frequency shifts are decisive in providing better quantitative estimates of the nonradiative decay rates and the experimentally observed temperature effects. Moreover, spin–orbit coupling, which is often considered only in the context of radiative decay rate, has a significant role in determining the nonradiative rate as well.     

Nonheme Iron Mediated Oxidation of Light Alkanes with Oxone: Characterization of Reactive Oxoiron(IV) Ligand Cation Radical Intermediates by Spectroscopic Studies and DFT Calculations

The oxidation of light alkanes that is catalyzed by heme and nonheme iron enzymes is widely proposed to involve highly reactive {Fe^V?O} species or {Fe^IV?O} ligand cation radicals. The identification of these high‐valent iron species and the development of an iron‐catalyzed oxidation of light alkanes under mild conditions are of vital importance. Herein, a combination of tridentate and bidentate ligands was used for the generation of highly reactive nonheme {Fe?O} species. A method that employs [Fe^III(Me₃tacn)(Cl‐acac)Cl]⁺ as a catalyst in the presence of oxone was developed for the oxidation of hydrocarbons, including cyclohexane, propane, and ethane (Me₃tacn=1,4,7‐trimethyl‐1,4,7‐triazacyclononane; Cl‐acac=3‐chloro‐acetylacetonate). The complex [Fe^III(Tp)₂]⁺ and oxone enabled stoichiometric oxidation of propane and ethane. ESI‐MS, EPR and UV/Vis spectroscopy, ¹⁸O labeling experiments, and DFT studies point to [Fe^IV(Me₃tacn)({Cl‐acac}^.+)(O)]²⁺ as the catalytically active species.     

DielsAlder Cyclization of a Dihydropyridine: NMR Spectroscopy,X‐Ray Crystallography,and DFT Computations. Bent Aromatic Dimeric Clusters in the Solid Phase

Structural studies of the N‐(2,4‐dinitrophenyl) derivative of a Diels? Alder‐cyclized 1,2‐dihydropyridine both unequivocally established the polycyclic framework and revealed interesting distortions of aromatic structure and unique dimeric clustering of the aromatic entities in the solid state.     

Photoacclimation Responses of the Brown Macroalga Sargassum Cymosum to the Combined Influence of UV Radiation and Salinity: Cytochemical and Ultrastructural Organization and Photosynthetic Performance

The photoacclimation responses of the brown macroalga Sargassum cymosum were studied to determine its cytochemical and ultrastructural organization, as well as photosynthetic pigments and performance. S. cymosum was cultivated in three salinities (30, 35 and 40 psu) under four irradiation treatments: PAR‐only, PAR + UVA, PAR + UVB and PAR + UVA + UVB. Plants were exposed to PAR at 70 μmol photons m^?2 s^?1, PAR + UVB at 0.35 W m^?2 and PAR +UVA at 0.70 W m^?2 for 3 h per day during 7 days in vitro. Growth rate was not significantly affected by any type of radiation or salinity. The amount of pigments in S. cymosum was significantly influenced by the interaction of salinity and radiation treatments. Compared with PAR‐only, UVR treatments modified the kinetics patterns of the photosynthesis/irradiance curve. After exposure to UVR, S. cymosum increased cell wall thickness and the presence of phenolic compounds. The number of mitochondria increased, whereas the number of chloroplasts showed few changes. Although S. cymosum showed insensitivity to changes in salinity, it can be concluded that samples treated under four irradiation regimes showed structural changes, which were more evident, but not severe, under PAR + UVB treatment.     

Development and validation of a rapid and sensitive UPLC–MS/MS assay for simultaneous quantification of paclitaxel and cyclopamine in mouse whole blood and tissue samples

The prominent stromal compartment surrounds pancreatic ductal adenocarcinoma and protects the tumor cells from chemo‐ or radiotherapy. We hypothesized that our nano formulation carrying cyclopamine (CPA, stroma modulator) and paclitaxel (PTX, antitumor agent) could increase the permeation of PTX through the stromal compartment and improve the intratumoral delivery of PTX. In the present study a sensitive, reliable UPLC–MS/MS method was developed and validated to quantify PTX and CPA simultaneously in mouse whole blood, pancreas, liver and spleen samples. Docetaxel was used as the internal standard. The method demonstrated a linear range of 0.5–2000 ng/mL for whole blood and tissue homogenates for both PTX and CPA. The accuracy and precision of the assay were all within ±15%. Matrix effects for both analytes were within 15%. Recoveries from whole blood, liver, spleen and pancreas homogenates were 92.7–105.2% for PTX and 72.8–99.7% for CPA. The stability was within ±15% in all test biomatrices. The validated method met the acceptance criteria according to US Food and Drug Administration regulatory guidelines. The method was successfully applied to support a pharmacokinetic and biodistribution study for PTX and CPA in mice biomatrices.     

The active and passive sampling of benzene, toluene, ethyl benzene and xylenes compounds using the inside needle capillary adsorption trap device

A new and simple method of solventless extraction of volatile organic compounds (VOCs) from air is presented. The sampling device has an adsorbing carbon coating on the interior surface of a hollow needle, and is called the inside needle capillary adsorption trap (INCAT). This paper describes a study of the reproducibility in the preparation and sampling of the INCAT device. In addition, this paper examines the effects of sample volume in active sampling and exposure time in passive sampling on the analyte adsorption. Analysis was achieved by sampling the air from an environmental chamber doped with benzene, toluene, ethyl benzene and xylenes (BTEX) compounds. Initial rates of adsorption were found to vary among the different compounds, but ranged from 0.0099 to 0.016 nmol h(-1) for passive sampling and from 2.2 to 10 nmol h(-1) for active sampling. Analysis was done by thermal desorption of the adsorbed compounds directly into a gas chromatograph injection port. Quantification of the analysis was done by comparison to actively sampled activated carbon solid phase extraction (SPE) measurements.     

Aggregation and C-N rotation of the lithium salt of N,N-dimethyldiphenylacetamide

[formula: see text] Two methyl 1H NMR signals for the Li salt of N,N-dimethyldiphenylacetamide are observed at low temperature and assigned to the monomer and dimer. From line shape analysis, the dimerization constant (K1,2) is 40 +/- 10 M-1 at 200 K (delta G degree = 1.5 kcal mol-1, delta H degree = 0.8 kcal mol-1, delta S degree = 12 eu) and the activation parameters are delta H++ = 5.5 kcal mol-1 and delta S++ = -18 eu. The C-N bond rotation is too fast to observe on the NMR time scale, indicating a rotation barrier of less than 10 kcal mol-1.