Novel (Phenothiazinyl)Vinyl-Pyridinium Dyes and Their Potential Applications as Cellular Staining Agents

We report here the synthesis and structural characterization of novel cationic (phenothiazinyl)vinyl-pyridinium (PVP) dyes, together with optical (absorption/emission) properties and their potential applicability as fluorescent labels. Convective heating, ultrasound irradiation and mechanochemical synthesis were considered as alternative synthetic methodologies proficient for overcoming drawbacks such as long reaction time, nonsatisfactory yields or solvent requirements in the synthesis of novel dye (E)-1-(3-chloropropyl)-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium bromide 3d and its N-alkyl-2-methylpyridinium precursor 1c. The trans geometry of the newly synthesized (E)-4-(2-(7-bromo-10-ethyl-10H-phenothiazin-3-yl)vinyl)-1-methylpyridin-1-ium iodide 3b and (E)-1-methyl-4-(2-(10-methyl-10H-phenothiazin-3-yl)vinyl)pyridin-1-ium tetrafluoroborate 3a′ was confirmed by single crystal X-ray diffraction. A negative solvatochromism of the dyes in polar solvents was highlighted by UV-Vis spectroscopy and explanatory insights were supported by molecular modeling which suggested a better stabilization of the lowest unoccupied molecular orbitals (LUMO). The photostability of the dye 3b was investigated by irradiation at 365 nm in different solvents, while the steady-state and time-resolved fluorescence properties of dye 3b and 3a′ in solid state were evaluated under one-photon excitation at 485 nm. The in vitro cytotoxicity of the new PVP dyes on B16-F10 melanoma cells was evaluated by WST-1 assay, while their intracellular localization was assessed by epi-fluorescence conventional microscopy imaging as well as one- and two-photon excited confocal fluorescence lifetime imaging microscopy (FLIM). PVP dyes displayed low cytotoxicity, good internalization inside melanoma cells and intense fluorescence emission inside the B16-F10 murine melanoma cells, making them suitable staining agents for imaging applications.     

A Unified Variational Volume Registration Method Based on Automatically Learned Brain Structures

We introduce a new volumetric registration technique that effectively combines active surfaces with the finite element method. The method simultaneously aligns multi-label automatic structural segmentation results, which can be obtained by the application of existing segmentation software, to produce an anatomically accurate 3D registration. This registration is obtained by the minimization of a single energy functional. Just like registering raw images, obtaining a 3D registration this way still requires solving a fundamentally ill-posed problem. We explain through academic examples as well as an MRI dataset with manual anatomical labels, which are hidden from the registration method, how the quality of a registration method can be measured and the advantages our approach offers.     

Interactions Between Calix[8]arenes and Fullerenes. Molecular Dynamics and Molecular Mechanics Simulation of the 1:1 and 1:2 complexes

Abstract

The interaction of tBu-calix[8]arene with C60 and C70 in the 1:1 and 1:2 models have been investigated by means of molecular dynamics and molecular mechanics (CVFF91 force field) calculations. The results reveal that one C60 molecule can be encapsulated in the cavity of the calixarene which adopts a conformation with six phenyl groups oriented upward and the other two (1 and 5) outward. The relatively weak bonded 1:1 C60-calixarene system is a result of attractive π…H(C-tBu. C-methylene) and repulsive π…π interactions. C70, more voluminous than C60 can not be accommodated in the cavity of the calixarcnc and forces it to a relatively opened conformation where the number of atractive interactions is less than in the C60-calixarene system. This conformation allows however the interaction with a second molecule and thus 1:2 adducts are formed. Thus, if proper substituents are on the calixarene and the fullerene size permite the encapsulation, 1:1 complexes are obtainable while if the fullerene size is larger than the cavity of the calixarene can cope with, only the 1:2 adducts can be separated.

     

Stable Isomers of Sila - and Germadodecahedrane. a Semiempirical (Am1) Investigation of the Structure of 4/6 and 4/5/6 Ring Containing E20 (E=SI, GE) Systems

AMI molecular orbital calculations with full geometry optimisation of 4/6, 5/5 and 4/5/6 isomers of E₂₀ (E=Si, Ge) show a clear preference of germanium to be accommodated in four membered rings and to achieve coordination numbers greater than 3 (V A). as a consequence, unlike C₂₀ or Si₂₀, the dodecahedral form of Ge₂₀ was not localised on the potential surface, instead an opened structure derived from an octagermaprismane (IV B) can be predicted. Notable kinetic stabilisation in the (SiR)₂₀ systems is suggested by the HOMO-LUMO differences.     

Preparation and magnetoelectric properties of NiFe2O4–PZT composites obtained in-situ by gel-combustion method

Magnetoelectric composites of xNiFe₂O₄–(1 ? x)Pb(Zr,Ti)O₃ with x = 2, 5, 10, 20, 30% were prepared by citrate–nitrate combustion using PZT-based template powders. In order to ensure a better connectivity of dissimilar phases, we have used chemical methods for preparation in situ composites, followed by adequate sintering procedure. The structural, microstructural and functional properties of di-phase magnetoelectric composites of NiFe₂O₄–PZT are reported. The XRD analysis is demonstrating the synthesis of pure ferrite phase directly on the ferroelectric templates. An excellent mixing was obtained in the composite powders, as proved by a detailed SEM analysis.The magnetic and dielectric behaviors of the ceramic composites vary with the ratio of the two phases. The dielectric behavior is greatly influenced by the magnetic phase. The magnetoelectric (ME) coefficient was measured as a function of applied DC magnetic field. The maximum ME coefficient (dE/dH) varies from 0.0011 mV/(cm Oe) to 0.5 mV/(cm Oe) with increasing of NF addition.     

Cationic polyelectrolytes,XI. Polymers with quaternary N-atoms in the main chain obtained by condensation polymerization of epichlorohydrin with amines

Water soluble cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorohydrin (ECH) with dimethylamine (DMA) and N,N-dialkylaminoalkylamines. The main parameters of the reaction that influence the polymer properties are: DMA/asymmetrical diamine molar ratio, the initial concentration of amine solution, NaOH/amine molar ratio, ECH/amine molar ratio, and asymmetrical diamine structure. The feature of flexible polyelectrolyte own to the investigated polymers was emphasized by the viscosimetric behaviour in dilute aqueous solutions with and without salt presence.