New tetrazine-based fluoroelectrochromic window; modulation of the fluorescence through applied potential

A new electrofluorescent switch was prepared with an electroactive fluorescent tetrazine blend of polymer electrolyte; the cells contain four layers: the tetrazine polymer film, a photocured polymer electrolyte film, and two indium-tin oxide plates as the two contact electrodes.     

Lifts of - and -morphisms to -morphisms

Let be the Hochschild complex of cochains on and let be the space of multivector fields on . In this paper we prove that given any -structure (i.e. Gerstenhaber algebra up to homotopy structure) on , and any -morphism (i.e. morphism of a commutative, associative algebra up to homotopy) between and , there exists a -morphism between and that restricts to . We also show that any -morphism (i.e. morphism of a Lie algebra up to homotopy), in particular the one constructed by Kontsevich, can be deformed into a -morphism, using Tamarkin's method for any -structure on . We also show that any two of such -morphisms are homotopic.

     

Revisiting the reactivity of oximate alpha-nucleophiles with electrophilic phosphorus centers. Relevance to detoxification of sarin, soman and DFP under mild conditions

Following a potentiometric determination of the relevant pKa values of the (R1R2)C=NOH functionality, the second order rate constants (k(Ox)) for reaction of a large set of oximate bases with two model organophosphorus esters, i.e. bis-(4-nitrophenyl)phenylphosphonate (BNPPP) and bis-(4-nitrophenyl)methylphosphonate (BNPMP), and three toxic compounds, i.e., sarin (GB), soman (GD) and diisopropylphosphorofluoridate (DFP), in aqueous as well as a 30 : 70 (v/v) H2O-Me2SO mixture have been measured. The corresponding Br?nsted-type nucleophilicity plots of log k(Ox)vs. pKa(Ox) reveal a clear tendency of the reactivity of the oximates to suffer a saturation effect with increasing basicity in aqueous solution. In the case of BNPMP and the three toxic esters, this behaviour is reflected in a levelling off at pKa approximately 9 but a more dramatic situation prevails in the BNPPP system where the attainment of maximum reactivity at pKa approximately 9 is followed by a clear decrease in rate at higher pKa's. Interestingly, a number of data reported previously by different authors for the sarin, soman and DFP systems are found to conform rather well to the curvilinear Br?nsted correlations built with our data. Based on this and previous results obtained for reactions at carbon centers, it can be concluded that the observed saturation effect is the reflection of an intrinsic property of the oximate functionality. An explanation of this behavior in terms of an especially strong requirement for desolvation of the oximates prior to nucleophilic attack which becomes more and more difficult with increasing basicity is suggested. This proposal is supported by the observed changes in pKa(Ox) and k(Ox) brought about by a transfer from H2O to a 30 : 70 H2O-Me2SO mixture. The implications of the saturation effect on the efficiency of oximates as nucleophilic catalysts for smooth decontamination are emphasized. Also discussed is the effect of basicity on the exalted (alpha-effect) reactivity of these bases.     

Lifting the mirror symmetry of metal surfaces: decoupling the electronic and physical manifestations of surface chirality

Naturally occurring metal surfaces possess planes of mirror symmetry on the nanometer-length scale. This mirror symmetry can be lifted and chirality "physically" conveyed onto a surface by adsorbing a chiral molecule. Until now, it has not been known whether the conveying of chirality is limited to just the physical structure or whether it goes deeper and permeates the electronic structure of the underlying surface. By using optically active second harmonic generation (OA-SHG), it is demonstrated that the adsorption of some, but not all, chiral molecules can reversibly, and without significant structural rearrangement, measurably lift the mirror symmetry of the surface electronic structure of a metal. It is proposed that the ability of a chiral molecule to place a significant "chiral perturbation" on the electronic structure of a surface is correlated to its adsorption geometry. The microscopic origins of the observed optical activity are also discussed in terms of classical models of chirality. The results of the study challenge current models of how chiral adsorbates induce enantioselectivity in the chemical/physical behavior of heterogeneous systems, which are based on geometric/stereochemical arguments, by suggesting that chiral electronic perturbations could play a role.     

One- and Two-Photon Phototherapeutic Effects of RuII Polypyridine Complexes in the Hypoxic Centre of Large Multicellular Tumor Spheroids and Tumor-Bearing Mice**

During the last decades, photodynamic therapy (PDT), an approved medical technique, has received increasing attention to treat certain types of cancer. Despite recent improvements, the treatment of large tumors remains a major clinical challenge due to the low ability of the photosensitizer (PS) to penetrate a 3D cellular architecture and the low oxygen concentrations present in the tumor center. To mimic the conditions found in clinical tumors, exceptionally large 3D multicellular tumor spheroids (MCTSs) with a diameter of 800 μm were used in this work to test a series of new Ru^II polypyridine complexes as one-photon and two-photon PSs. These metal complexes were found to fully penetrate the 3D cellular architecture and to generate singlet oxygen in the hypoxic center upon light irradiation. While having no observed dark toxicity, the lead compound of this study showed an impressive phototoxicity upon clinically relevant one-photon (595 nm) or two-photon (800 nm) excitation with a full eradication of the hypoxic center of the MCTSs. Importantly, this efficacy was also demonstrated on mice bearing an adenocarcinomic human alveolar basal epithelial tumor.     

Reliable reduced-order models for time-dependent linearized Euler equations

Development of optimal reduced-order models for linearized Euler equations is investigated. Recent methods based on proper orthogonal decomposition (POD), applicable for high-order systems, are presented and compared. Particular attention is paid to the link between the choice of the projection and the efficiency of the reduced model. A stabilizing projection is introduced to induce a stable reduced-order model at finite time even if the energy of the physical model is growing. The proposed method is particularly well adapted for time-dependent hyperbolic systems and intrinsically skew-symmetric models. This paper also provides a common methodology to reliably reduce very large nonsymmetric physical problems.     

Azide‐functionalized nanoparticles as quantized building block for the design of soft–soft fluorescent polystyrene core—PAMAM shell nanostructures

This work deals with the covalent coupling of azide‐functionalized polymeric nanoparticles as a reactive core and amino‐terminated PAMAM dendrons as a reactive shell. The nanoassemblies thereby obtained could be modified after the dendronization step by grafting an alkynyl Bodipy dye on the unreacted azide moieties. Only a few steps are required to attain nanoassemblies that could mimic dendrimers of high generation with sizes of nano‐objects beyond those of dendrimers. The structure of the nanoassemblies are composed of a polystyrene core, an inner shell including the Bodipy dyes along with the internal branches of the PAMAM, and the terminal amino groups from the outer shell. The dendritic shell acts as a protective layer that prevents NP from aggregation in a surfactant free aqueous solution. The nano‐objects display absorption and emission maxima above 500 nm with brightness that are the same order of magnitude than Qdots. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 115–126