Search results for "Ionic polymerization"

2017

Two cationic Ir(III) complexes bearing 2-phenylpyridinato cyclometalating ligands and bithiazole-type ancillary ligands have been synthesized and optoelectronically characterised. These emitters exhibit unusually deep red-to-near-infrared emission at room temperature, thereby rendering them as attractive emitters in solution-processed light emitting electrochemical cell (LEEC) electroluminescent devices.

O-Doped Nanographenes: A Pyrano/Pyrylium Route Towards Semiconducting Cationic Mixed-Valence Complexes

2020

Herein we report an efficient synthesis to prepare O‐doped nanographenes, which derive from the longitudinally and latitudinally p‐extension of pyrene. The derivatives are highly fluorescent and feature low‐oxidation potentials. Exploiting electrooxidation, crystals of cationic mixed valence (MV) complexes were grown in which the organic salts organize into face‐to‐face p‐ p stacks, a favorable solid‐state arrangement for organic electronics. Variable‐temperature EPR measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar p‐stacking architectures. Electric measurements of single crystals of the MV salts exhibited a semiconduct…

EMPLOYMENT OF CATIONIC SOLID-LIPID NANOPARTICLES AS RNA CARRIERS

2007

Gene transfer represents an important advance in the treatment of both genetic and acquired diseases. In this article, the suitability of cationically modified solid-lipid nanoparticles (SLN) as a nonviral vector for gene delivery was investigated, in order to obtain stable materials able to condense RNA. Cationic SLN were produced by microemulsion using Compritol ATO 888 as matrix lipid, Pluronic F68 as tenside, and dimethyldioctadecylammonium bromide (DDAB) as cationic lipid. The resulting particles were approximately 100 nm in size and showed a highly positive surface charge (+41 mV) in water. Size and shape were further characterized by scanning electron microscopy (SEM) measurements. M…

QSAR of Natural Sesquiterpene Lactones as Inhibitors of Myb-dependent Gene Expression

2017

Background Protein c-Myb is a therapeutic target. Some sesquiterpene lactones suppress Myb-dependent gene expression, which results in their potential anti-cancer activity. Material & methods Database ChEMBL is a representative of lactones for physicochemical and physiochemical properties. Data presented for 31 natural lactones are discussed in terms of quantitative structureactivity relationships with the objective to predict inhibitors of Myb-induced gene expression. Several constitutional descriptors are related to structure-activity. α-Methylene-γ-lactone groups enhance while OH functions worsen potency. The latter feature is in agreement with the fact that the more lipophilic the lacto…

Antisymmetric exchange in triangular tricopper(II) complexes: correlation among structural, magnetic, and electron paramagnetic resonance parameters.

2011

Two new trinuclear copper(II) complexes, [Cu(3)(μ(3)-OH)(daat)(Hdat)(2)(ClO(4))(2)(H(2)O)(3)](ClO(4))(2)·2H(2)O (1) and [Cu(3)(μ(3)-OH)(aaat)(3)(H(2)O)(3)](ClO(4))(2)·3H(2)O (2) (daat = 3,5-diacetylamino-1,2,4-triazolate, Hdat = 3,5-diamino-1,2,4-triazole, and aaat = 3-acetylamino-5-amino-1,2,4-triazolate), have been prepared from 1,2,4-triazole derivatives and structurally characterized by X-ray crystallography. The structures of 1 and 2 consist of cationic trinuclear copper(II) complexes with a Cu(3)OH core held by three N,N-triazole bridges between each pair of copper(II) atoms. The copper atoms are five-coordinate with distorted square-pyramidal geometries. The magnetic properties of 1 …

Morphology of hybrid polystyrene-block-poly(ethylene oxide) micelles: Analytical ultracentrifugation and SANS studies

2006

Abstract Morphology and structure of aqueous block copolymer solutions based on polystyrene- block -poly(ethylene oxide) (PS- b -PEO) of two different compositions, a cationic surfactant, cetyl pyridinium chloride (CPC), and either platinic acid (H 2 PtCl 6 ⋅6H 2 O) or Pt nanoparticles were studied using a combination of analytical ultracentrifugation (AUC), transmission electron microscopy (TEM), and small angle neutron scattering (SANS). These studies combining methods contributing supplemental and analogous structural information allowed us to comprehensively characterize the complex hybrid systems and to discover an isotope effect when H 2 O was replaced with D 2 O. In particular, TEM s…

Pores Formed by Baxα5 Relax to a Smaller Size and Keep at Equilibrium

2010

AbstractPores made by amphipathic cationic peptides (e.g., antimicrobials and fragments of pore-forming proteins) are typically studied by examining the kinetics of vesicle leakage after peptide addition or obtaining structural measurements in reconstituted peptide-lipid systems. In the first case, the pores have been considered transient phenomena that allow the relaxation of the peptide-membrane system. In the second, they correspond to equilibrium structures at minimum free energy. Here we reconcile both approaches by investigating the pore activity of the α5 fragment from the proapoptotic protein Bax (Baxα5) before and after equilibrium of peptide/vesicle complexes. Quenching assays on …

Combining reactive triblock copolymers with functional cross-linkers: A versatile pathway to disulfide stabilized-polyplex libraries and their applic…

2017

Therapeutic nucleic acids such as pDNA hold great promise for the treatment of multiple diseases. These therapeutic interventions are, however, compromised by the lack of efficient and safe non-viral delivery systems, which guarantee stability during blood circulation together with high transfection efficiency. To provide these desired properties within one system, we propose the use of reactive triblock copolypept(o)ides, which include a stealth-like block for efficient shielding, a hydrophobic block based on reactive disulfides for cross-linking and a cationic block for complexation of pDNA. After the complexation step, bifunctional cross-linkers can be employed to bio-reversibly stabiliz…

Cationic Nanohydrogel Particles as Potential siRNA Carriers for Cellular Delivery

2012

Oligonucleotides such as short, double-stranded RNA (siRNA) or plasmid DNA (pDNA) promise high potential in gene therapy. For pharmaceutical application, however, adequate drug carriers are required. Among various concepts progressing in the market or final development, nanosized hydrogel particles may serve as novel transport media especially for siRNA. In this work, a new concept of synthesizing polymeric cationic nanohydrogels was developed, which offers a promising strategy to complex and transport siRNA into cells. For this purpose, amphiphilic reactive ester block copolymers were synthesized by RAFT polymerization of pentafluorophenyl methacrylate as reactive ester monomer together wi…

Synthesis and reactivity of the novel hydride derivative RhHCl(TIMP3) (HTIMP3 = tris[1-(diphenylphosphino)-3-methyl-1H-indol-2-yl]methane)

2009

The reaction of HTIMP(3) (HTIMP(3) = tris[1-(diphenylphosphino)-3-methyl-1H-indol-2-yl]methane) with [RhCl(COD)](2) and Rh(acac)(CO)(2) produces RhHCl(TIMP(3)) (1H) and Rh(TIMP(3))(CO) (2), respectively, both exhibiting tetradentate kappaC,kappa(3)P-coordination of the TIMP(3) moiety. The reaction of RhHCl(TIMP(3)) with nucleophiles (L) in the presence of AgBF(4) or AgPF(6) produces different compounds depending on the nature of L. Indeed, cationic Lewis adducts of formula [RhH(L)(TIMP(3))](+) ((2H+)-(5H+)) are obtained when L is CO, CNCH(2)Ph, pyridine or CH(2)CHCN. On the other hand, when the incoming nucleophile is CH(3)COOH the hydride-free complex [Rh(CH(3)COO)(TIMP(3))](+) ((6+)) is o…