P4VP and oligo(phenylenevinylene)‐perylenebisimide mixed donor‐acceptor supramolecular comb polymer complexes with improved charge carrier mobility

Random donor‐acceptor (D‐A) supramolecular comb polymers were formed when hydroxyl functionalized donor and acceptor small molecules based on Oligo(phenylenevinylene) (named OPVCN‐OH ) and Perylenebisimide (named UPBI‐PDP ), respectively, were complexed with Poly(4‐vinyl pyridine) (P4VP). A series of random D‐A supramolecular comb polymers were formed by varying the ratios of UPBI‐PDP and OPVCN‐OH with P4VP. A 100% P4VP‐donor polymer complex [ P4VP(OPV_1.00 )] and a 100% P4VP‐acceptor polymer complex [ P4VP(UPBI_1.00 )] were also synthesized and characterized. Complex formation was confirmed by FT‐IR and ¹H NMR spectroscopy. Solid state structural studies carried out using small angle X‐ray scattering and wide angle X‐ray diffraction experiments revealed altered packing of the D and A molecules in the complexes. Transmission electron microscopy images showed lamellar structures in the < 10 nm scale for the P4VP(OPV_1.00 ), P4VP(UPBI_1.00 ), and mixed P4VP (D‐A) complexes. The effect of the nanoscopic D‐A self‐assembly on the bulk mobility of the materials was probed using SCLC measurements. The mixed D‐A random complexes exhibited ambipolar charge transport characteristics with higher values for the average bulk hole mobility estimate. P4VP(OPV_0.25 + UPBI_0.75) exhibited an average hole mobility in the order of 10^?2cm² V^?1 s^?1 and electron mobility 10^?5cm² V^?1 s^?1. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2403–2412     

Electronic Circular Dichroism Spectra of DNA Quadruple Helices Studied by Molecular Dynamics Simulations and Excitonic Calculations including Charge Transfer States

We here investigate the Electronic Circular Dichroism (ECD) Spectra of two representative Guanine-rich sequences folded in a Quadruple helix (GQ), by using a recently developed fragment diabatisation based excitonic model (FrDEx). FrDEx can include charge transfer (CT) excited states and consider the effect of the surrounding monomers on the local excitations (LEs). When applied to different structures generated by molecular dynamics simulations on a fragment of the human telomeric sequence (Tel21/22), FrDEx provides spectra fully consistent with the experimental one and in good agreement with that provided by quantum mechanical (QM) method used for its parametrization, i.e., TD-M05-2X. We show that the ECD spectrum is moderately sensitive to the conformation adopted by the bases of the loops and more significantly to the thermal fluctuations of the Guanine tetrads. In particular, we show how changes in the overlap of the tetrads modulate the intensity of the ECD signal. We illustrate how this correlates with changes in the character of the excitonic states at the bottom of the La and Lb bands, with larger LE and CT involvement of bases that are more closely stacked. As an additional test, we utilised FrDEx to compute the ECD spectrum of the monomeric and dimeric forms of a GQ forming sequence {"type":"entrez-nucleotide","attrs":{"text":"T30695","term_id":"612793"}}T30695 (5′TGGGTGGGTGGGTGGG3′), i.e., a system containing up to 24 Guanine bases, and demonstrated the satisfactory reproduction of the experimental and QM reference results. This study provides new insights on the effects modulating the ECD spectra of GQs and, more generally, further validates FrDEx as an effective tool to predict and assign the spectra of closely stacked multichromophore systems.     

Green synthetic approaches for biologically relevant organic compounds

The present review aims to present some framework of the effective and diverse green methodologies in conventional and unconventional media including water, solar energy, ionic liquids, ultrasonication and bio-based catalysts which constitute an important goal in organic synthesis and can be used to strengthen conventional laboratory techniques.     

An Error Analysis of Discontinuous Finite Element Methods for the Optimal Control Problems Governed by Stokes Equation

In this article, an abstract framework for the error analysis of discontinuous finite element method is developed for the distributed and Neumann boundary control problems governed by the stationary Stokes equation with control constraints. A priori error estimates of optimal order are derived for velocity and pressure in the energy norm and the L²-norm, respectively. Moreover, a reliable and efficient a posteriori error estimator is derived. The results are applicable to a variety of problems just under the minimal regularity possessed by the well-posedness of the problem. In particular, we consider the abstract results with suitable stable pairs of velocity and pressure spaces like as the lowest-order Crouzeix–Raviart finite element and piecewise constant spaces, piecewise linear and constant finite element spaces. The theoretical results are illustrated by the numerical experiments.     

Simple and Efficient Synthesis of 5-Substituted-3-phenyl-2-thioxoimidazolidin-4-one Derivatives from S-Amino Acids and Phenylisothiocyanate in Et3N/DMF-H2O

A concise approach for the transformation of various S-amino acids into the 5-alkyl-3-phenyl-2-thioxoimidazolidin-4-one heterocycles using phenylisothiocyanate is described. Phenylthiohydantoins of amino acid were synthesized at room temperature in Et₃N/DMF-H₂O with easy workup and excellent yields.     

Chalcogen Bond Mediated Enhancement of Cooperative Ion‐Pair Recognition

A series of heteroditopic receptors containing halogen bond (XB) and unprecedented chalcogen bond (ChB) donors integrated into a 3,5‐bis‐triazole pyridine structure covalently linked to benzo‐15‐crown‐5 ether motifs exhibit remarkable cooperative recognition of halide anions. Multi‐nuclear ¹H, ¹³C, ¹²⁵Te and ¹⁹F NMR, ion pair binding investigations reveal sodium cation–benzo‐crown ether binding dramatically enhances the recognition of bromide and iodide halide anions, with the chalcogen bonding heteroditopic receptor notably displaying the largest enhancement of halide binding strength of over two hundred‐fold, in comparison to the halogen bonding and hydrogen bonding heteroditopic receptor analogues. DFT calculations suggest crown ether sodium cation complexation induces a polarisation of the sigma hole of ChB and XB heteroditopic receptor donors as a significant contribution to the origin of the unique cooperativity exhibited by these systems.     

β-Cyclodextrin catalyzed one-pot four component auspicious protocol for synthesis of spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-trione as a potential antimicrobial agent

We have developed an perceptive and facile approach for the synthesis of new spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-trione derivatives (4a–t) by one-pot four component condensation involving two equivalence of dimedone (1), substituted anilines (2a–t), and isatin (3) catalyzed by β-cyclodextrin in water within short reaction time at 80?°C in good to excellent yields. We believe that this novel procedure may open the door for the easy generation of new and bioactive spiro[acridine-9,3′-indole]-2′,4,4′(1′H,5′H,10H)-triones. The most exciting feature of this methodology is its mechanism involving the unusual ring opening of an isatin moiety followed by recyclization. Synthesized compounds were evaluated for their antimicrobial activities against four bacteria and three fungi. All the spirooxindole derivatives exhibited significant antibacterial activity against bacteria and fungi. Among 20 compounds screened, compound (4i) and (4h) was found to be more active against tested bacterial strain.     

Synthesis,characterization, and hyperpolarizability measurements of main‐chain azobenzene molecules

A series of new AB type azobenzene monomers based on various substituted phenols and higher order fused/extended aromatic rings were synthesized and their hyperpolarizability tensor β determined by hyper‐Rayleigh scattering (HRS) measurement in methanol. The electron donor (? OH) and acceptor units (? COOH) were kept constant in the series, but the effective conjugation length was varied by varying the number and position of substituents as well as the number of aromatic rings. The effect of substitution of the phenolic ring on the β value was investigated and it was found to range from 15 × 10^?30 to 42 × 10^?30 esu. The effect of intramolecular hydrogen bonding on the nonlinear optical (NLO) property was also examined. The nonlinearity was in the following order of phenol derivative: α‐naphthol > phenyl phenol > 2,6‐dimethyl phenol > o‐cresol > cardanol > phenol > β‐naphthol. The unusually low values for the β‐naphthol‐based chromophore compared with its isomer (α‐naphthol) could be rationalized based on hydrogen bonding of the o‐hydroxyl group with the β nitrogen of the azo bridge. These azobenzene NLO chromophoric monomers were polymerized to form main‐chain polymers with a head to tail structure. The polymers had high thermal stability and rather low solubility in common organic solvents. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4455–4468, 2005     

Radial oscillations of magnetized proto strange stars in temperature- and density-dependent quark mass model

We report on the study of the mass-radius (M–R) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modification, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We find that the effect of magnetic field, both on the maximum mass and radial frequencies, is rather small. Also a proto strange star, whether magnetized or otherwise, is more likely to evolve into a strange star rather than transform into a black hole.     

ROS Dependent Antifungal and Anticancer Modulations of Piper colubrinum Osmotin

Osmotin, a plant defense protein, has functional similarity to adiponectin, an insulin sensitizingsensitising hormone secreted by adipocytes. We speculated that Piper colubrinum Osmotin (PcOSM) could have functional roles in obesity-related cancers, especially breast cancer. Immunofluorescence assays, flow cytometry, cell cycle analysis and a senescence assay were employed to delineate the activity in MDAMB231 breast cancer cell line. PcOSM pre-treated P. nigrum leaves showed significant reduction in disease symptoms correlated with high ROS production. In silico analysis predicted that PcOSM has higher binding efficiency with adiponectin receptor compared to adiponectin. PcOSM was effectively taken up by MDAMB231 cancer cells which resulted in marked increase in intracellular ROS levels leading to senescence and cell cycle arrest in G2/M stage. This study provides evidence on the ROS mediated direct inhibitory activity of the plant derived osmotin protein on the phytopathogen Phytophthora capsici, and the additional functional roles of this plant defense protein on cancer cells through inducing ROS associated senescence. The strong leads produced from this study could be pursued further to obtain more insights into the therapeutic potential of osmotin in human cancers.