Ermüdungsprodukte des photochromen 2-(2′,4′-Dinitrobenzyl)-pyridins

Fatigue Products of Photochromic 2-(2′,4′-Dinitrobenzyl)-pyridine Under prolonged irradiation or frequent repetitions of its photochromic cycle, 2-(2′,4′-dinitrobenzyl)-pyridine 1 shows fatigue phenomena both in solid state and in solution. These phenomens — yellow discoloration, depression of the melting point, decrease of band intensity of the coloured form, shorter lifetime of the coloured form — are caused by irreversible redox processes and subsequent reactions at the methylene and ortho-nitro groups which are essential for photochromism. Azomethine 2 , ketone 3 and amine 4 are isolated as the major fatigue products.     

Synthese und Eigenschaften kristallin-flüssiger Derivate des Rhodanins

Synthesis and Properties of Liquid Crystalline Derivatives of Rhodanine Substituted benzylidene-rhodanines 3 – 8 were prepared both by condensation of 1 a – f with suitable aldehydes and by acylation of 2a – g with substituted benzoyl chlorides or cinnamoyl chlorid. The mesomorphic properties of the compounds are discussed in respect to molecular structure with the aid of i.r.-, Raman- and u.v./vis-spectra of 3d , 3k , 4 , 5 , 6g , 8a . We have investigated the dielectric and electrooptic behaviour of 31 .     

Crystallography and Structure–Property Relationships in 2,2′,2″,2′′′,4,4′,4″,4′′′,6,6′,6″,6′′′‐Dodecanitro‐1,1′ : 3′1″ : 3″,1′′′‐ Quaterphenyl (DODECA)

X‐ray crystallographic study of 2,2′,2″,2′′′,4,4′,4″,4′′′,6,6′,6″,6′′′‐dodecanitro‐1,1′ : 3′1″ : 3″,1′′′‐quaterphenyl (DODECA) has been carried out. Nonbonding interatomic distances of oxygen atoms inside of all the nitro groups are shorter than those corresponding to the intermolecular contact radii for oxygen. By means of the DFT B3LYP/6‐31(d, p) method a difference of 136 kJ mol⁻¹ between the X‐ray and DFT structures of DODECA was found. The bearer of the highest initiation reactivity in its molecule in solid phase should be the nitro group at 4′′′‐position, in contrast to those at 2′‐ or 2″‐positions in its isolated molecule. The most reactive nitro group in the DODECA molecule can be well specified by the relationship between net charges on nitro groups and charges on their nitrogen atoms, both of them for the X‐ray structure. The ¹⁵N chemical shift, corresponding to this nitro group for the initiation by impact and shock, correlates very well with these shifts of the reaction centers of the other six “genuine” polynitro arenes.     

Synthesis of 3′,4′‐disubstituted terthiophenes. Characterization and electropolymerization. I. 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene in photovoltaic display

Recent studies on conducting polymers have demonstrated that polymers of 3‐substituted thiophene produce very stable compounds. Although this kind of substitution improves the regularity, structural defects still exist. To overcome this drawback, the polymerization of 3,4‐disubstituted thiophene is proposed as a convenient way of synthesizing regular, highly conjugated conductive polymers. Our interest is thus focused on the synthesis of tetra‐substituted thiophene derivatives, their polymerization, electrochemical properties, spectral characteristics, oxidizing potential, and the feasibility of photocells development. In this article, we report the synthesis and characterization of 3′,4′‐dibromo‐2,2′:5′,2″‐terthiophene which, as such or modified, may be a good starting product for obtaining new monomers of 3′,4′‐disubstituted terthiophenes, that would allow the effect of the substituents on the properties of the respective polymers to be studied. In addition, the monomer was electropolymerized and the resulting deposit was electrochemically and morphologically characterized. Two conclusions were drawn: first, more uniform and homogeneous layers than those of polythiophene are obtained; second, the thin layers of the polymer, electron acceptors, absorb in the visible. Finally, photocells were assembled to investigate their photovoltaic effect. Although the so prepared solar cells showed some photovoltaic effect, the yield was low.© 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5314–5321, 2006     

Synthesis and hydrolysis study of polyacrylates containing 2′,5-dichloro-4′-nitrosalicylanilide

Monomers (meth)acryloyloxy-2′,5-dichloro-4′-nitrosalicylanilide have been synthesized by treating 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) with acryloyl or methacryloyl chloride, and polymerized by free radical polymerization to give a polymer containing chemically bonded niclosamide. The structure of monomer and polymer were confirmed by IR, UV, and elemental analysis. Hydrolysis data of polymer in different media indicated that the hydrolysis rates of polymer were strongly dependent on the nature of the polymer structure and the hydrolyzing medium. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 29–33, 1997     

Katalytische und elektrochemische Aktivität einiger Metall-Polyphthalocyanine

The catalytic properties of Fe, Co, Cu, Ni and Mg polyphthalocyanines in the reaction of hydrogen peroxide decomposition and their electrochemical properties in the reaction of oxygen reduction have been investigated. The accordance of the orders of catalytic and electrochemical activities of the investigated metallic polyphthalocyanines has been stated. The influence of reaction environment on catalytic and electrochemical activities also has been found. It has been established, that the linear dependence between reaction rate constant of hydrogen peroxide and its electrical conductivity, for iron polyphthalocyanine soluble in concentrated sulphuric acid can be observed.     

Intumescent flame-retardant system of phosphates and 5,5,5′,5′,5″,5″-hexamethyltris (1,3,2-dioxaphosphorinanemethan)amine 2,2′,2″- trioxide for polyolefins

A new halogen-free intumescent flame-retardant system was developed using melamine phosphates and 5,5,5′,5′,5″,5″- hexamethyltris (1,3,2- dioxaphosphorinanemethan) amine 2,2′,2″-trioxide (XPM-1000, Monsanto Co.). This intumescent system, optimally at a weight ratio of about 1 : 2, showed effective flame retardancy by oxygen index (OI) and UL 94 tests in ethylene–vinyl acetate (EVA) and polyolefin formulations. At a constant loading and a constant weight ratio of phosphate/XPM-1000, the flame-retardant effectiveness was influenced by the phosphates in the order of melamine pyrophosphate > melamine phosphate ≈︁ dimelamine phosphate > melamine amyl phosphate. The rate of char formation, as measured under flaming conditions, appeared to correlate better than did the char yield to the observed flame-retardant effectiveness of the different phosphate/XPM-1000 combinations and to the different ratios of phosphate/XPM-1000. A test procedure was developed to measure the char-forming rate which proved to be well correlated with flame retardancy. The possible composition of intumescent char was suggested based on infrared, XPS, and elemental analysis. The presence of polycondensed phosphorus acids with some P NH bonds appears likely. Such phosphorus-nitrogen species may help explain the observed synergism, since their formation could reduce the volatility of the phosphorus acids and enable them to better protect the char. © 1996 John Wiley & Sons, Inc.     

Synthese und Charakterisierung photochromer 2,2′-Dinitro-diphenylmethane

Synthesis and Characterization of Photochromic 2,2′-Dinitrodiphenylmethanes Photochromic methyl-, amino-, nitro- and formyl-derivatives of 2,2′-dinitro-diphenylmethane 1 are synthesized by nitration of the substituted diphenylmethanes. They react with aromatic aldehydes or activated benzylcompounds respectively to the photochromic compounds 6a, 6b and 5c–5f containing phenyl-vinylen and phenyl-azavinylen units. Condensations with corresponding bifunctional compounds yield oligomers, the Knoevenagel-product is soluble and photochromic. The synthesized 2,2′-dinitro-diphenylmethanes are photochromic in solution. The thermal back reaction is described by first order kinetics. Methyl groups decrease and, on the other hand, nitro functions increase the lifetime of the coloured polymethinform.     

Photoconductivity of 1,2‐(1′,1′,2′,2′‐tetracyanomethanoxymethano)[60]fullerene‐doped PVK

1,2‐(1′,1′,2′,2′‐Tetracyanomethanoxymethano)[60]fullerene, a derivative of C₆₀, is a better electron acceptor than the parent C₆₀. The film of PVK doped with 1.6 wt % of this derivative was prepared and characterized. The micromorphology of the film was studied by transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM). The photoinduced discharge curves and photoconduction spectra of the films were measured. The results showed that PVK doped with the C₆₀ derivative displayed more photoconductivity than that of PVK doped with pure C₆₀ or a mixture of C₆₀ and C₇₀. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 209–213, 1999     

The structure and photocatalytic performances of mechanically synthesized poly(3′,4′‐ethylenedioxy‐2,2′:5′,2″‐Terthiophene)/Zno composites

Poly(3′,4′‐ethylenedioxy‐2,2′:5′,2″‐terthiophene)/ZnO(poly(TET)/ZnO) composites with the ratio of poly(TET) and nano‐ZnO from 3:1 to 1:3 were synthesized by hand grinding and ball milling methods, respectively. The photocatalytic activities of the composites were examined through the degradation processes of methylene blue (MB) solution under UV light irradiation, and the possible mechanism for the photocatalytic activity enhancement by synergetic effects between nano‐ZnO and poly(TET) was proposed. The results showed that the strong interactions between the poly(TET) and nano‐ZnO occurred in the case of ball milling method. The results also proved that the crystallinity of ZnO was not disturbed in both of methods, and the nano‐ZnO was uniformly distributed in polymer matrix in the case of ball milling method. The comparative studies showed that the addition of the nano‐ZnO could enhance the photocatalytic activities of the composites. The highest degradation efficiency (100%) at 3 h under UV light irradiation occurred in the case of poly(TET)/ZnO(1:1) synthesized by ball milling method. Furthermore, the nanocompsosite displayed higher photocatalytic activity than nano‐ZnO, which was due to the holes (h⁺) transferring from the valence band of ZnO to the polymer backbone and the adsorption of MB molecules in polymer matrix via π–π conjugation between MB and aromatic regions of the poly(TET). POLYM. COMPOS., 36:1597–1605, 2015. © 2014 Society of Plastics Engineers     

Synthesis of new flame-retarding epoxy resin based on 3′, 5′, 3″, 5″-tetrabromophenolphthalein

New flame-retarding epoxy is synthesized by reacting 3′, 5′, 3Prime;, 5″-tetrabromophenolphthalein (TBPP) with epichlorohydrin and characterized in comparison with commercially available tetrabromobisphenol-A(TBBA) epoxy on their flame retardancy and thermostability. TBPP epoxy show better results in promoting flame resistance than TBBA epoxy. However, TBPP epoxy exhibits a greater effect on thermal decomposition temperature. The order of char yield at 800°C under nitrogen for the cured products is TBPP epoxy > phenolphthalein (PP) epoxy > TBBA epoxy. Meanwhile, there is a linear relationship between oxygen index and char yield for cured products of TBPP-PP epoxy and TBBA-BA epoxy systems.