Search

An efficient synthetic strategy that includes protection–modification–deprotection consequence was successfully developed to obtain novel water-soluble, amphiphilic, surface-active maltodextrin-based glycosilicones.

We devise a high-carrier-mobility hole-transport layer with less hole loss, obtained via doping poly(9-vinylcarbazole) into poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-butylphenyl)))], achieving high external quantum efficiency QLEDs (22.7%).

Photoluminescent lanthanide complexes of Eu3+ and Tb3+ as central atoms and N6,N6’-diisopropyl-[2,2′-bipyridine]-6,6′-dicarboxamide as ligand were synthesized. The structure of these complexes was established by single-crystal X-ray diffraction, mass spectrometry, 1H and 13C nuclear magnetic resonance, ultraviolet-visible, infrared spectroscopy, and thermogravimetry. Bipyridinic ligands provide formation of coordinatively saturated complexes of lanthanide ions and strong photoluminescence (PL). The Eu3+- and Tb3+-complexes exhibit PL emission in the red and green regions observed at a 340 nm excitation. The quantum yield for the complexes was revealed to be 36.5 and 12.6% for Tb3+- and Eu3+-complexes, respectively. These lanthanide compounds could be employed as photoluminescent solid-state compounds and as emitting fillers in polymer (for example, polyethylene glycol) photoluminescent materials.

Rubber materials are the key components of flexible optoelectronic devices, especially for the light-emitting diodes based on arrays of inorganic nanowires (NWs). This paper reports on polydimethylsiloxane-graft-polystyrene (PDMS-St) as a new flexible substrate of GaP NW array structures. The NWs were encapsulated by the newly introduced G-coating method to substitute the inefficient mainstream spin-coating. To further exploit the flexibility and the stretchability of the NW/PDMS-St structures, the ferrocenyl-containing polymethylhydrosiloxane was synthesized and successfully used as an electrode for the NWs. In order to make an alternative highly efficient transparent electrode, a new application of conductive single-walled carbon nanotubes was demonstrated. The novel materials and methods demonstrated unsurpassed mechanical stability of the fabricated flexible electronic devices.

4-Substituted O-benzyl benzamide oximes reacted with 2-iodobenzonitrile in the presence of 0.1 mol % of [Pd2(dba)3], 0.2 mol % of XantPhos, and 1.5 equiv of Cs2CO3 in dioxane under argon to give 2-arylquinazolin-4-amines. The described reaction is a new type of cascade processes, which affords 4-amino-quinazoline derivatives without using highly reactive chlorinating agents.

Flexible optoelectronic structures are required in a wide range of applications. Large scale modified silicone-embedded n-GaP nanowire arrays of a record 6 µm thin membranes were studied. A homogeneous silicone encapsulation was enabled by G-coating using a heavy-load centrifuge. The synthesized graft-copolymers of polydimethylsiloxane (PDMS) and polystyrene demonstrated two times lower adhesion to Si compared to standard PDMS, allowing 3 square inch area high quality silicone/nanowire membrane mechanical release, preserving the growth Si substrate for a further re-use after chemical cleaning. The 90% transparent single-walled carbon nanotubes electrical contacts to the embedded n-GaP nanowires demonstrated mechanical and electrical stability. The presented methods can be used for the fabrication of large scale flexible inorganic optoelectronic devices.

Cyclic organosilicon triperoxides were found to be vinyl-selective free-radical initiators for thermal curing at 100–180 °C of vinyl-terminated polydimethylsiloxane and trimethylsilyl-terminated polymethylhydrosiloxane producing homogeneous transparent silicone rubbers with antibacterial properties. The usage of the cyclic organosilicon triperoxides as the curing agents does not require free radical inhibitors in comparison with diacyl- and dialkyl peroxides. Among the tested compounds, the peroxide with the Me–Si–Me fragment and two cyclohexane rings is a much more active curing agent (180 °C, c = 0.22 M, τcuring = 45 min) than other organosilicon peroxides. Cured silicone samples from mixtures with vinyl-terminated polysiloxane and silicone hydride have improved mechanical properties: peroxides provide more than 200% elongation, and compression sets of the samples are less than 1%. The prepared silicone rubbers showed pronounced antibacterial activity.

Experimental data on the application of metal complexes in radical polymerization of vinyl monomers collected over the recent 15 years have been analyzed and generalized. Special attention has been given to (un)substituted ferrocenes, macrocyclic (clathro)chelates, and iron porphyrinates as well as to the approaches to enhance their catalytic activity in controlled synthesis of macromolecules. The mentioned systems have been compared with each other as well as with selected complexes of other transition metals. It has been shown that the electronic and spatial structures of the metal complexes are related to their efficiency in the radical polymerization reactions.

The effect of the binary catalytic systems [the Karstedt catalyst–platinum(II) isocyanide complex] of the cure of vinyl-containing polydimethylsiloxane and hydride-containing siloxane oligomer via the hydrosilylation reaction has been studied.

The nitrile complexes trans-[PtCl2 (RCN)2 ] (R=Et (NC1), tBu (NC2), Ph (NC3), p-BrC6 H4 (NC4)) and cis-[PtCl2 (RCN)2 ] (R=Et (NC5), tBu (NC6), Ph (NC7)) react with 1 equiv of the hydroxyguanidine OC4 H8 NC(=NOH)NH2 (HG) furnishing the mono-addition products trans- and cis-[PtCl2 (RCN){NH=C(R)ON=C(NH2 )NC4 H8 O}] (1-4 and 9-11; 7 examples; 54-74 % yield). Treatment of any of the nitrile complexes NC1-NC7 with HG in a 1:2 molar ratio generated the bis-addition products trans- and cis-[PtCl2 {NH=C(R)ON=C(NH2 )NC4 H8 O}2 ] (5-8 and 12-14; 7 examples; 69-89 % yield). The PtII -mediated coupling between nitrile ligands and HG proceeds substantially faster than the corresponding reactions involving amid- and ketoximes and gives redox stable products under normal conditions. Complexes 1, 6⋅4 CH2 Cl2 , 7⋅4 CH2 Cl2 , 8⋅2 CH2 Cl2 , and NC4 were studied by X-ray crystallography. Platinum(II) species 1-3, 10, 11, and especially 9, efficiently catalyze the hydrosilylation cross-linking of vinyl-terminated poly(dimethylsiloxane) and trimethylsilyl-terminated poly(dimethylsiloxane-co-ethylhydrosiloxane) giving high-quality thermally stable silicon resins with no structural defects. The usage of these platinum species as the catalysts does not require any inhibitors and, moreover, the complexes and their mixtures with vinyl- and trimethylsilyl-terminated polysiloxanes are shelf-stable in air.

Cyclic peroxides as initiators for the radical polymerization of methyl methacrylate were proposed. The initial rates, initiation rates, and effective activation energies of polymerization initiated by cyclic peroxides and cyclic peroxide-1-pyridyl-2-ferrocene systems were determined. The radical yields to the volume upon the thermal decomposition of cyclic peroxides and their catalytic decomposition in the presence of 1-pyridyl-2-ferrocene were determined. In combination with 1-pyridyl-2-ferrocene cyclic peroxides form efficient initiating systems favoring an increase in the polymerization rate, a decrease in the molecular weights, and an increase in syndiotacticity of the synthesized poly(methyl methacrylate). © 2013 Springer Science+Business Media New York.

Physicochemical methods were used to study the interaction of arabinogalactan from Siberian larch with the antibacterial preparation levofloxacin. Polymeric eye films with controllable output of the medicinal preparation were produced on the basis of an arabinogalactan-polyvinyl alcohol formulation. A high pharmaceutical activity of the new eye films was demonstrated.

The effect of initiating systems based on substituted and unsubstituted metallocenes; polynuclear macrocyclic semi- and clathrochelates of Fe(II); and metal complexes of Ti(IV), Zr(IV), Fe(III), and Co(III) porphyrins on the free-radical polymerization of MMA and styrene is analyzed. Experimental data are systematized, general relationships are ascertained, and specific features of the process related to the structure of metal-complex compounds and the nature of initiators and monomers are revealed.

200 The use of metal complex compounds in radical polymerization of vinyl monomers is one of the most successful and promising ways of development of tai lor made synthesis of polymers on their basis [1, 2]. It has been shown [3–6] that iron(II) semi and clathro chelates in combination with traditional initiators of radical polymerization (in particular, diacyl perox ides) form high performance initiating systems. Such systems have a favorable effect on both the kinetic parameters of the process (increase the initiation rate; under certain conditions, mitigate the detrimental gel effect; reduce the effective activation energy of poly merization; etc.) and the physicochemical character istics of the resulting polymers (variation of the molec ular weight from 300 thousand daltons to 4 million daltons, the increase in stereoregularity and thermal stability). In this context, the use of new types of clath rochelates, in particular, macrobicyclic cobalt(II) tris(α dioximate)s (Scheme 1, compounds 1–3), as modifying additives in the radical polymerization of methyl methacrylate (MMA) initiated by benzoyl per oxide seems to be promising. All these compounds dif fer from the previously studied cage iron(II) com plexes [3–6] in the nature of both the encapsulated metal ion and the apical and edge substituents.

Influence of 1-[pyridyl-2]-, 1-[quinolin-2-yl]-, 1-[acridin-9-yl]-, 1-[pyrazin-2-yl]-, and 1-[pyrimid-4-yl]ferrocenes on heat and thermomechanical properties of the produced poly(methyl methacrylate) has been studied.

The effect of ferrocenyl-containing semi- and clathrochelates on radical polymerization of methyl methacrylate, initiated by benzoyl peroxide, and on molecular characteristics of the polymer formed was examined.

Radical polymerization of methyl methacrylate initiated by the benzoyl peroxide — macrobicyclic bis-ferrocenylboron-capped iron(ii) tris-1,2-cyclohexanedione dioximate system was studied. The ferrocenyl-containing macrobicyclic complex and benzoyl peroxide forms an efficient initiating system that allows one to perform the polymerization process at a high rate with substantially reduced amounts of the initiator and the metal complex component at 30–75 °C and to influence the molecular-weight characteristics of poly(methyl methacrylate) produced.

A series of ferrocenylboron-capped tris-dioximate iron(ii) clathrochelates was synthesized by the template condensation of three molecules of dimethylglyoxime (H2Dm), cyclohexanedione 1,2-dioxime (H2Nx), or cyclooctanedione 1,2-dioxime (H2Ox) and two molecules of ferrocenylboronic acid (FcB(OH)2) on the Fe2+ ion matrix. The yields of the clathrochelate derivatives of alicyclic dioximes were substantially higher than that of their acyclic analog, because the molecules of alicyclic H2Nx and H2Ox α-dioximes have the s-cis-configuration suitable for complex formation, whereas the H2Dm molecules in solution have the s-trans-configuration. The synthesized compounds were characterized using elemental analysis, IR and UV-Vis spectroscopies, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR and 57Fe Mossbauer spectroscopies, and X-ray diffraction analysis. The crystal of FeDm3(BFc)2·CHCl3 contains two types of crystallographically nonequivalent clathrochelate molecules. The intermolecular contacts C-H⋯Cp formed by the ferrocenyl fragments and cyclooctane carbocycles and the interactions Cp-H⋯O were observed in the crystal of FeOx3(BFc)2. The structural lability of the cyclooctane substituents allows the FeOx3(BFc)2 molecules to arrange by the “bump-into-hollow” mode because of attractive H⋯H interactions between the ribbed substituents of the neighboring molecules. The geometry of the ferrocenylborate iron(ii) clathrochelates is intermediate between a trigonal prism and a trigonal antiprism.

The direct template macrocyclization of 2,3-butanedione monooxime hydrazone (HDXO) with ferrocenylboronic acid on the iron(ii) ion matrix afforded the ferrocenylboron-capped semiclathrochelate iron(ii) oximehydrazonate. The H+ ion-catalyzed macrocyclization of this precursor with an excess of triethyl orthoformate gave the clathrochelate complex with syn,syn,syn-orientation of the ethoxy substituents relative to the 1,3,5-triazacyclohexane ring. The complexes synthesized were characterized using elemental analysis, IR and UV—Vis spectroscopies, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR, 57Fe Mossbauer spectroscopies, and X-ray diffraction analysis.

The effect of ternary initiating systems benzoyl peroxide-ferrocene-3,6-bis(o-carboxybenzoyl)-N-isopropylcarbazole and benzoyl peroxide-di-η5-indenylzirconium dichloride-3,6-bis(o-carboxybenzoyl)-N-isopropylcarbazole on the radical polymerization of methyl methacrylate and on the heat resistance and microstructure of the resulting polymers was examined.

The radical copolymerization of methyl pheophorbide A with styrene or methyl methacrylate in bulk or in benzene solution initiated by azobisisobutyronitrile at 60–90 °C was performed and kinetically characterized.

The role of the ferrocenium radical cation and Cp2Fe+–O radical in the initiation of methyl methacrylate polymerization in the absence and presence of oxygen was demonstrated.

The pivalate complexes of metals used in the radical polymerization of methyl methacrylate increase rate of process initiated by both benzoyl peroxide and azobisisobutyronitrile and decrease the molecular weight of the resulting polymethyl methacrylate.

Controlled radical polymerization of methyl methacrylate and styrene initiated by azobisisobutironitrile or benzoyl peroxide in the presence of a chlorine-containing complex of Fe III with 5,15-bis(4 ’ - tert -butylphenyl)-2,8,12,18-tetra( n -butyl)-3,7,13,17-tetramethylporphyrin was investigated.

The controlled radical polymerization of methyl methacrylate initiated by the ferrocene–zirconocene dichloride–benzoyl peroxide system was found to occur as a living radical process with an increased concentration of sindio-triads in the resulting poly(methyl methacrylate).