- UV spectroscopic studies and charge transfer properties of azobenzene-containing cyclopentadienyliron complexes of arenes: A combined experimental and density functional theoretical study
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This study investigates the UV-Vis absorption and fluorescence emission of newly synthesized (η6-4-(4-nitrophenylazo) phenoxyl benzene) (η5-cyclopentadienyl) iron hexafluorophosphate (Fc-azo). Quantum chemical calculations of the orbital energy, geometrical structure, absorption spectra, and first hyperpolarizability (β) values of the Fc-azo were carried out using density functional (DFT/B3LYP and TD-DFT) methods. Comparisons between hydroxyl azobenzene compound and Fc-azo were made. Results showed that the observed spectra were in good agreement with the calculated values. The positive solvatochromism of the UV-Vis absorption of Fc-azo upon the increase in solvent polarity from the experiment and the calculated HOMO and LUMO energies showed that charge transfer occurred within the molecule. Moreover, the change in electron distribution led to the improved β for Fc-azo.
- Li, Guang Lei,Liu, Ji Qiang,Zhao, Bao Dong,Wang, Tao
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Read Online
- Ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite as a new reagent for the efficient diazotization of aniline derivatives and in situ synthesis of azo dyes
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A new ionic liquid 1-(3-trimethoxysilylpropyl)-3-methylimidazolium nitrite was synthesized. This ionic liquid was used as a convenient nitrosonium source in diazotization of arylamines into their corresponding diazonium salts which were converted into their related azo dyes via the in situ azo-coupling with aniline derivatives or phenolic compounds. The diazotization of anilines in this ionic liquid and subsequent azo-coupling generated the related azo dyes in good to excellent yields at 0-5 °C in short reaction times via a simple experimental procedure.
- Valizadeh,Amiri,Shomali,Hosseinzadeh
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Read Online
- Nonlinear optical effects in polymeric azoesters
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The methacrylic monomers containing azobenzene moiety with flexible alkyl spacers of different lengths and groups of different nature are synthesized, and their physicochemical properties were determined by electronic absorption, 1H NMR spectroscopy, and element analysis. In the present work, the homopolymers built with the use of the free radical polymerization of methacrylic monomers incorporating an azobenzene side-group have been synthesized and structurally characterized. The results of photochemical and optical activities of the corresponding polymers are presented. Third-order nonlinear optical (NLO) properties of the azopolymer solutions are studied by the degenerate four wave mixing (DFWM) method.
- Nadtoka, Oksana,Krupka, Oksana,Luk, Jerome,Syromyatnikov, Volodymyr,Sahraoui, Bouchta,Smokal, Vitaliy
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Read Online
- Stimuli responsive materials supported by orthogonal hydrogen and halogen bonding or i···alkene interaction
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Smart materials represent an elegant class of (macro)-molecules endowed with the ability to react to chemical/physical changes in the environment. Herein, we prepared new photo responsive azobenzenes possessing halogen bond donor groups. The X-ray structures of two molecules highlight supramolecular organizations governed by unusual noncovalent bonds. In azo dye I-azo-NO2, the nitro group is engaged in orthogonal H···O···I halogen and hydrogen bonding, linking the units in parallel undulating chains. As far as compound I–azo–NH–MMA is concerned, a non-centrosymmetric pattern is formed due to a very rare I···π interaction involving the alkene group supplemented by hydrogen bonds. The Cambridge Structural Database contains only four structures showing the same I···CH2=C contact. For all compounds, an19F-NMR spectroscopic analysis confirms the formation of halogen bonds in solution through a recognition process with chloride anion, and the reversible photo-responsiveness is demonstrated upon exposing a solution to UV light irradiation. Finally, the intermediate I–azo–NH2 also shows a pronounced color change due to pH variation. These azobenzenes are thereby attractive building blocks to design future multi-stimuli responsive materials for highly functional devices.
- Frangville, Pierre,Gelbcke, Michel,Kumar, Shiv,Meyer, Franck,Van Hecke, Kristof
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- Two-Phase Electrochemical Generation of Aryldiazonium Salts: Application in Electrogenerated Copper-Catalyzed Sandmeyer Reactions
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The electrochemical generation of aryldiazonium salts from nitroarenes in a two-phase system (ethyl acetate/water) was reported for the first time. Some compounds including azo, azosulfone, and arylazides were prepared in good yields with good purity. Cathodically generated aryldiazoniums and anodically produced copper(Ι) ions were used to perform Sandmeyer reactions. To improve the method, an H-type self-driving cell equipped with a Zn rod as an anode was introduced and used for two-phase aryldiazonium production.
- Goljani, Hamed,Tavakkoli, Zahra,Sadatnabi, Ali,Nematollahi, Davood
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supporting information
p. 5920 - 5924
(2020/08/12)
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- Photoisomerization and Mesophase Formation in Azo-Ionic Liquids
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Ionic liquids present a versatile, highly tunable class of soft functional materials. Aside from being low melting salts, they can be endowed with additional functionalities. In N-alkylimidazolium halides, which are a prominent class of ionic liquids (ILs), the imidazolium cation was linked via an ether-bridge to an azobenzene unit in order to obtain photoresponsive materials through photoinduced trans-cis isomerization. The azobenzene unit, in turn, was modified with electron-donating or -withdrawing groups such as methyl-, tert-butyl-, methoxy-, N,N-dimethylamino, and nitro groups to study their influence on the photoisomerization and phase behavior. Endowing the imidazolium additionally with a long alkyl chain allows the materials to potentially form liquid crystalline (LC) mesophases before melting into the isotropic liquid. All studied compounds qualify as ionic liquids, and all, except for the nitro-compound, show the formation of smectic mesophases melting to the isotropic liquid. The compounds with the bulkiest aliphatic substituent, the tert-butyl, shows the lowest melting point, the largest mesophase window, and an efficient photochemical trans-cis conversion (>90%). In summary, by tuning sterically and electronically the cationic part of ILs, a photoswitchable room temperature liquid crystal could be developed and design guidelines for photoresponsive ionic liquids could be obtained.
- Renier, Olivier,Bousrez, Guillaume,Stappert, Kathrin,Wilk-Kozubek, Magdalena,Adranno, Brando,Pei, Hanwen,Spielberg, Eike T.,Smetana, Volodymyr,Mudring, Anja-Verena
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p. 214 - 225
(2019/12/24)
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- Can be alkaline dyeing of the bright yellow dispersion dye
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The invention discloses a bright yellow disperse dye capable of alkaline dyeing. The bright yellow disperse dye is a compound represented by a formula A, wherein R1 is -H, -CH3, -C2H5, -OCH3 or -OC2H5, and R2 is C1-C4 straight-chain or branched-chain alkyl or benzyl. The disperse dye shows a bright yellow color, can be used individually and also can be in combination use with alkali-resisting disperse dyes having other colors. The disperse dye has excellent alkali resistance and hydrogen peroxide oxidization resistance stability; the characteristic makes the disperse dye not only can be applied in general alkaline printing and dyeing processing of a polyester fiber material, but also can be applied in a scouring dyeing-bath process or a bleaching dyeing-bath process and a dispersed active one-paste printing process, and can meet the requirements of environmental protection.
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Paragraph 0129; 0130
(2017/12/07)
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- Nano-CuFe2O4-supported sulfonic acid as a novel and recyclable nanomagnetic acid for diazotization of aromatic amines: efficient synthesis of various azo dyes
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Abstract: A novel heterogeneous sulfonic acid functionalized nanomagnetic CuFe2O4 was successfully prepared and characterized by analyzing different obtained data including Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, dynamic light scattering and vibrating sample magnetometer. Then the novel acidic reagent was examined in synthesis of various azo-containing compounds from coupling of aryl diazonium ferrite sulfate salts with aromatic and non-aromatic compounds. The procedure starts by diazotization of aromatic amines with NaNO2 and wet CuFe2O4–SO3H and then coupling reaction of aryl diazonium ferrite sulfate salts with appropriate reagent. The prepared nano-solid acid showed high activity in synthesis of variety of aryl diazonium salts. In addition the as-prepared aryl diazonium ferrite sulfate salts are stable at room temperature for many hours and reacted efficiently in coupling reactions of aryl diazonium salts. All the azo dyes are synthesized in high yields and simple reaction conditions at room temperature. Moreover, the nanomagnetic solid acid was easily recovered from the reaction mixture and reused five runs without significant loss of activity. Graphical Abstract: [Figure not available: see fulltext.]
- Nemati, Firouzeh,Elhampour, Ali,Natanzi, Mahshid B.,Sabaqian, Samaneh
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p. 1045 - 1054
(2016/05/02)
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- Phase Difference Plate, Laminated Polarizing Plate Using the Phase Difference Plate and Display Device Using the Phase Difference Plate
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The present invention provides a phase difference plate, which inhibits the reduction of transmissivity to the minimum, has a desirable birefringent wavelength dispersion and an excellent reflecting angle of view characteristics, and a less fluctuation of dichroic ratio even under high temperature and humidity, and shows an improved optical reliability, a laminated polarizing plate using the same and a display device of viewing angle. According to the present invention, a birefringence of andDelta;n, as a phase difference plate having a characteristic of negative dispersion which becomes larger as a measuring wavelength is longer in at least some wavelength area of visible ray areas, comprises a polymerizable liquid crystal composition and a polymer formed by polymerizing one or more polymerizable dichroic dyes. In addition, provided is a phase difference plate in which a liquid crystal compound is formed with a liquid crystal film aligned with a nematic hybrid.(AA) andDelta;n of embodiment 1(BB) Ideal graph(CC) Wavelength (nm)COPYRIGHT KIPO 2016
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Paragraph 0215-0217
(2016/11/14)
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- Synthesis and characterization of azobenzene-based gold nanoparticles for photo-switching properties
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A series of new azobenzene based thiolated liquid crystals modified with gold nanoparticles were synthesized and characterized using a different mode of delegated tools e.g. FTIR, NMR and FESEM-EDX measurements for the structural properties of synthesized compounds. Polarized optical microscopy studies have revealed all the studied compounds having liquid crystalline properties, as a typical nematic phase. These liquid crystal capped gold nanoparticles' size was determined by TEM experiment. In addition, azobenzene-based gold nanoparticles containing flexible spacers showed photochromic behavior upon UV irradiation. These molecules exhibited strong photoisomerisation behavior in solutions and their trans to cis isomerisation took about 44 s whereas the reverse process almost took place ranging from 82 to 125 min.
- Biswas, Tapan Kumar,Sarkar, Shaheen M.,Yusoff, Mashitah M.,Rahman, Md Lutfor
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p. 231 - 237
(2016/02/23)
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- H-Bonding and charging mediated aggregation and emission for fluorescence turn-on detection of hydrazine hydrate
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In situ morphological transition and turn-on fluorescence of self-assembled NDI derivatives driven by hydrazine hydrate are realized through H-bonding and charging of aromatic building blocks, demonstrating a stimuli-responsive supramolecular system useful for visual detection of hydrazine hydrate.
- Zhou, Deyan,Wang, Yangyang,Jia, Jiong,Yu, Wenzhu,Qu, Baofeng,Li, Xia,Sun, Xuan
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supporting information
p. 10656 - 10659
(2015/06/30)
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- Carboxyl and nitrite functionalized graphene quantum dots as a highly active reagent and catalyst for rapid diazotization reaction and synthesis of azo-dyes under solvent-free conditions
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Carboxyl and nitrite functionalized graphene quantum dots was prepared from carboxyl and hydroxyl functionalized graphene quantum dots using NaNO2 in the absence of mineral acids. This functional group conversion was confirmed by FT-IR spectroscopy, photoluminescence and X-ray diffraction. The carboxyl and nitrite functionalized graphene quantum dots was used as an effective nitrosonium ion source and reusable catalyst for the efficient diazotization of a variety of arylamines without using any additional acid. Subsequent azo-coupling of these freshly prepared diazonium salts with a range of active aromatic compounds led to the requisite azo-dyes in excellent yields in very short reaction times with a simple experimental procedure.
- Valizadeh, Hassan,Shomali, Ashkan,Nourshargh, Saideh,Mohammad-Rezaei, Rahim
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p. 522 - 528
(2015/03/18)
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- Tunable heptamethine-azo dye conjugate as an NIR fluorescent probe for the selective detection of mitochondrial glutathione over cysteine and homocysteine
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Although a lot of mitochondria-targeting biothiol probes have been developed and applied to cellular imaging through thiol-induced disulfide cleavage or Michael addition reactions, relatively few probes assess mitochondrial GSH with high selectivity over Cys and Hcy and with NIR fluorescence capable of noninvasive imaging in biological samples. In order to monitor mitochondrial GSH with low background autofluorescence, we designed a heptamethine-azo conjugate as an NIR fluorescent probe by introducing a tunable lipophilic cation unit as the biomarker for mitochondria and a nitroazo group as the GSH-selective reaction site as well as the fluorescence quencher. The probe exhibited a dramatic off-on NIR fluorescence response toward GSH with high selectivity over other amino acids including Cys and Hcy. Further application to cellular imaging indicated that the probe was highly responsive to the changes of mitochondrial GSH in cells.
- Lim, Soo-Yeon,Hong, Keum-Hee,Kim, Dae Il,Kwon, Hyockman,Kim, Hae-Jo
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supporting information
p. 7018 - 7025
(2014/06/09)
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- Nematic phases in achiral unsymmetrical four-ring bent-core azo compounds possessing strongly polar cyano and nitro moieties as end substituents: Synthesis and characterization
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Achiral unsymmetrical four-ring bent-core liquid crystals with strongly polar cyano and nitro moieties as substituents at one end and alkyloxy group (butyl to dodecyl) at the other end have been synthesized by a simple and straight forward synthetic method. The four phenyl rings are connected through azo, ester and imine linkages respectively and bent unit is derived from 3-aminobenzoicacid with 2-methyl substituent in the transverse direction of the molecule. The molecular structure characterization is consistent with elemental and spectroscopic analysis data. The materials thermal behaviour and phase characterization have been investigated by differential scanning calorimetry and polarizing optical microscopy. All the compounds exhibit enantiotropic nematic phase over a wide temperature range. The light induced cis-trans isomerization is also discussed.
- Debnath, Somen,Mohiuddin, Golam,Turlapati, Srikanth,Begum, Nazma,Sarkar, Dipika Debnath,Nandiraju Rao
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p. 447 - 455
(2013/10/08)
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- Nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica for the diazotization of aniline derivatives and subsequent synthesis of azo dyes
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Imidazolium based nitrite ionic liquid containing trimethoxysilyl group was prepared from the reaction of N-methylimidazole and (3-chloropropyl) trimethoxysilane. This ionic liquid was immobilized on silica covalently to give nanoparticles with the imidazolium nitrite moiety remaining intact. The diazotization reaction was performed as a model reaction to examine the activity of these nanoparticles as a nitrosonium source. Excellent performance was exhibited in the diazotization reaction of various aniline derivatives in the presence of HCl under mild heterogeneous conditions (room temperature and short reaction time). In-situ coupling of diazonium salts to a range of tertiary anilines, phenols and naphthols afforded the requisite azo dyes in good yield, using standard experimental procedures.
- Valizadeh, Hassan,Amiri, Mohammad,Hosseinzadeh, Fatemeh
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experimental part
p. 1308 - 1313
(2012/03/27)
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- A reaction-based colorimetric fluoride probe: Rapid naked-eye detection and large absorption shift
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Taking advantage of both the well-known azobenzene structure and the special fluoride-promoted cleavage reaction of the Si-O bond, a new ratiometric colorimetric probe (F-1) toward the fluoride anion was designed and synthesized by using intramolecular charge transfer (ICT) as a signal mechanism. Upon the addition of F- ions, the probe displayed apparent color changes from colorless to deep blue, with a dramatic shift of the maximum absorption wavelength (≈230 nm). With the aid of UV/Vis measurements, the detection limit could be as low as 15 μM. The probe possessed much higher selectivity for fluoride over other common anions. Excitingly, by virtue of a dipstick approach, F-1 could serve as colorimetric probe for convenient measurements, without the requirement of any additional equipment.
- Cheng, Xiaohong,Li, Shuang,Xu, Guohua,Li, Conggang,Qin, Jingui,Li, Zhen
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p. 908 - 913
(2013/01/15)
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- Structure requirements for anaerobe processing of azo compounds: Implications for prodrug design
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This Letter generalizes the metabolism of the azo class of compounds by Clostridium perfringens, an anaerobe found in the human colon. A recently reported 5-aminosalicylic acid-based prednisolone prodrug was shown to release the drug when incubated with the bacteria, while the para-aminobenzoic acid (PABA) based analogue did not. Instead, it showed a new HPLC peak with a relatively close retention time to the parent which was identified by LCMS as the partially reduced hydrazine product. This Letter investigates azoreduction across a panel of substrates with varying degrees of electronic and steric similarity to the PABA-based compound. Azo compounds with an electron donating group on the azo-containing aromatic ring showed immediate disproportionation to their parent amines without any detection of hydrazine intermediates by HPLC. Compounds containing only electron withdrawing groups are partially and reversibly reduced to produce a stable detectable hydrazine. They do not disproportionate to their parent amines, but regenerate the parent azo compound. This incomplete reduction is relevant to the design of azo-based prodrugs and the toxicology of azo-based dyes.
- Gavin, Jason,Ruiz, Juan F. Marquez,Kedziora, Kinga,Windle, Henry,Kelleher, Dermot P.,Gilmer, John F.
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p. 7647 - 7652
(2013/02/21)
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- A new nitrite ionic liquid (IL-ONO) as a nitrosonium source for the efficient diazotization of aniline derivatives and in-situ synthesis of azo dyes
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A new task-specific nitrite containing ionic liquid derived from the O-nitrosation of N-methyl-N-hydroxybutylimidazolinium chloride was synthesized and used as a source of nitrosonium ion to affect the efficient diazotization of arylamines. The diazonium salts thus obtained were coupled, using standard experimental procedures, to a range of tertiary anilines, phenols and naphthols to afford the requisite azo dyes in good yield. The diazotization and subsequent azo-coupling generated the related azo dyes at 0-5 °C in short reaction times with a simple experimental procedure.
- Valizadeh, Hassan,Shomali, Ashkan
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experimental part
p. 1138 - 1143
(2012/03/27)
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- Synthesis and characterization of photoactive azobenzene-based chromophores containing a bulky cholesteryl moiety
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This study describes the synthesis of a series of azobenzene-based chromophores bearing pendent bulky cholesteryl groups, using esterification reactions. The chromophores were composed of liquid crystalline mesophases with six or eleven methylene segments as spacers, and with electron-donating (OCH3) and electron-withdrawing (NO2) terminal groups. The target compounds were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, polarizing optical microscopy, absorption, and photoluminescence spectroscopies. All the azobenzene derivatives with six or eleven methylene segments revealed chiral nematic phases. We investigated the effects of these photochromic compounds' structures on E/Z photoisomerization under UV irradiation. Chromophores containing the electron-withdrawing nitro-group (NO2) underwent a faster rate of Z to E isomerization in darkness than the electron-donating (OCH3) groups did; the isomerization process proceeded via a rotation mechanism. Self-assembled aggregates of C6 solution exhibited enhanced fluorescence in THF/water mixtures at 10% water fraction.
- Yang, Po-Chih,Lu, Ya-Ling,Li, Chung-Yuan
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scheme or table
p. 129 - 137
(2012/06/04)
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- Dinuclear ortho-metallated palladium(II) azobenzene complexes with acetato and chloro bridges: Influence of polar substituents on the mesomorphic properties
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The synthesis, characterization and mesomorphic properties of a new series of acetate and chloro-bridged dinuclear orthopalladated complexes derived from azobenzene with terminal groups of hexadecyloxy moiety at one end and different polar groups (Me, Cl, F, NO2, CN) at the other end are described. The mesomorphic properties of both the ligands and complexes were investigated by polarizing optical microscopy and X-ray studies to understand the effect of polar group in the nature of mesophase produced. Among the complexes, all chloro-bridged complexes predominantly exhibited SmA phase. However the rare phenomenon of observing mesomorphism in acetato-bridged palladium (II) complexes due its typical open book shape had been realized in substituted acetato-bridged complexes with fluoro and cyano substituents in the ligands. Nitro and cyano substituted ligands only exhibited monotropic Smectic A phase. Model molecular arrangement based on X-ray studies is presented.
- Choudhury, Trirup Dutta,Shen, Yongqiang,Rao, Nandiraju V.S.,Clark, Noel A.
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experimental part
p. 20 - 28
(2012/07/14)
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- Micelle-mediated extraction and cloud point pre-concentration for the spectrophotometric determination of phenol in water samples
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In this paper, a cloud point extraction method for the determination of trace amounts of phenol by spectrophotometry is described. The method is based on the colour reaction of phenol with diazotized p-nitroanilinean alkaline media and the cloud point ext
- Zarei, Ali Reza,Gholamian, Forouzan,Chalavi, Soheila
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experimental part
p. 158 - 162
(2012/03/27)
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- Optimization of the azobenzene scaffold for reductive cleavage by dithionite; development of an azobenzene cleavable linker for proteomic applications
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In this paper we conducted an extensive reactivity study to determine the key structural features that favour the dithionite-triggered reductive cleavage of the azo-arene group. Our stepwise investigation allowed identification of a highly reactive azo-arene structure 25 bearing a carboxylic acid, at the ortho position of the electron-poor arene and an ortho-Oalkyl-resorcinol as the electron-rich arene. Based on this 2(2′-alkoxy-4′-hydroxyphenylazo) benzoic acid (HAZA) scaffold, the orthogonally protected difunctional azo-arene cleavable linker 26 was designed and synthesized. Selective linker deprotection and derivatization was performed by introducing an alkyne reactive group and a biotin affinity tag. This optimized azo-arene cleavable linker led to a total cleavage in less than 10 s with only 1 mM dithionite. Similar results were obtained in biological media.
- Leriche, Geoffray,Budin, Ghyslain,Brino, Laurent,Wagner, Alain
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supporting information; experimental part
p. 4360 - 4364
(2010/09/20)
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- Synthesis of diaryl-azo derivatives as potential antifungal agents
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As compared with a commercially available agricultural fungicide hymexazol, some phenyl-azo phenol derivatives (e.g., 4a, 4b, 4f, 4n, 4q, 4u, and 4v) exhibited the more promising and pronounced antifungal activities in vitro against seven phytopathogenic fungi. It seemed that 4-((un)substituted phenylazo)-phenol and 4-((un)substituted phenylazo)-3-methylphenol might be considered as new lead structures for further design of agricultural fungicides.
- Xu, Hui,Zeng, Xiwen
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supporting information; experimental part
p. 4193 - 4195
(2010/08/22)
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- Fluorine-substituted azobenzene destabilizes polar form of optically switchable fulgimide unit in copolymer system
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Fulgimide and various size and electronic nature of substituents on the terminal position of azobenzene in the pendant homo/copolymethacrylates were synthesized. Differential scanning calorimetry analysis indicates the homopolymer possessing C-form fulgimide unit exhibited higher Tm than that of E-form of the homopolymer and revealed C-form is highly ordered. Thermal stability suggests azobenzene homopolymers with electron donating substituents have high thermal stability than electron withdrawing substituents. Polarized optical microscopy observation disclosed homopolymers viz., NI, CY, FL, ME, and T-ME exhibited liquid crystalline mesophases between their Tm and Ti. Optical properties of homo/copolymers were investigated by UV-vis and fluorescence spectroscopy. UV-vis spectroscopy displayed C-form fulgimide absorption in F-co-FL around 482 nm which is around 40 nm lesser than C-form of substituted azobenzene copolymers. Similarly, fluorescence pattern of F-co-FL by UV irradiation exhibited emission intensity slowly increased to certain level then decreases with two new emissions at 430 and 480 nm attributed to terminal position of fluorine atom on azobenzene destabilizes polar form (C-form) fulgimide unit in the copolymer.
- Chinnusamy, Saravanan,Palaninathan, Kannan
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scheme or table
p. 1565 - 1578
(2011/02/26)
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- Colorimetric detection of cyanide with a chromogenic oxazine
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A chromogenic oxazine compound for the colorimetric detection of cyanide was designed. Indeed, the [1,3]oxazine ring of our compound opens to form a phenolate chromophore in response to cyanide. The heterocyclic com-pound may be comprised of fused benzoox
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Page/Page column 2; 8
(2009/10/21)
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- Can be azo dyes obtained by grinding under solvent-free conditions?
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The solid-solid reactions of some electron-donors with sulfanilic acid in the presence of solid sodium nitrite afford azo dyes by self-catalyzed diazotization of sulfanilic acid (2) under solvent-free conditions with moderate yields. Also the reactions of some electron-donors with diazotization of o-nitroaniline (5), m-nitroaniline (6) and p-nitroaniline (7) in the presence of solid sodium nitrite catalyzed by p-toluenesulfonic acid (PTSA) afford azo dyes under solvent-free conditions in good yields. This new method totally avoids the use of acids, alkalies, and toxic and/or expensive solvents in diazotization and diazo coupling reactions.
- Noroozi-Pesyan, Nader,Khalafy, Jabbar,Malekpoor, Zahra
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experimental part
p. 1018 - 1027
(2010/09/10)
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- Solvatochromic effects in the absorption spectra of some azobenzene compounds
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Solvatochromic behavior of some 4,4′-substituted azoaromatic derivatives has been investigated in solvents of different polarities. The solvent dependent UV/vis spectral shifts, νmax, were analyzed using some physical parameters such as refractive index, dielectric constant, Kamlet-Taft parameters α (hydrogen bond donating ability) and β (hydrogen bond accepting ability). The intermolecular interaction types in the azobenzene derivatives solutions were established on the basis of a multiple linear regression analysis. The fitting coefficients obtained from this analysis allowed us to estimate the contribution of each type of interactions to the total spectral shift in the studied solutions.
- Rusu, Elena,Dorohoi, Dana-Ortansa,Airinei, Anton
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experimental part
p. 216 - 219
(2009/02/06)
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- Spacer length influence on the electrooptic effect of methacrylic azopolymer series
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Methacrylic azopolymers with different spacer lengths in side chains have been synthesized. The spectra and kinetics of the electrooptic effect which arises in azopolymer films after their irradiation by linearly polarized light are investigated. The photo-induced optical anisotropy in the films appears due to a change of the concentration ratio of trans- and cis-isomers of azobenzene fragments. This explains the nature of the electrooptic effect. Owing to a mobility increment of azobenzene fragments by means of the spacer extension, the electrooptic effect becomes more pronounced, and its relaxation time decreases.
- Nadtoka,Davidenko,Studzinsky,Syromyatnikov
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scheme or table
p. 261/[593]-267/[599]
(2010/03/25)
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- Photoinduced spatial orientational order in methacrylic azopolymers
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The combination of the transmission null ellipsometry and the total absorption method is applied to study the 3D orientational configurations of azochromophores in polymethacrylates with azobenzene side groups. The transformation of the initial orientation due to the photoexcitation of azochromophores is investigated. Under irradiation, if the reorientation mechanism of the photoinduced ordering prevails, the azochromophores are reoriented perpendicularly to the polarization direction of the exciting light, Eex. In the case where the photoselection ordering mechanism dominates, the 3D distribution of azochromophores in the saturation state of irradiation is isotropic due to a strong exhaustion of the number of anisotropic trans isomers. The observed regularities were earlier described for several other classes of photosensitive polymers, and so they may be common rules for the photoordering in photochromic media.
- Nadtoka, Oksana,Syromyatnikov, Vladimir,Olkhovik, Lidiya,Yaroshchuk, Oleg,Bidna, Tetyana
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- Synthesis and liquid crystalline properties of a disc-shaped molecule with azobenzene at the periphery
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A triphenylene-based novel liquid crystal was synthesised whose peripheral cores are six rod-like azobenzene moieties linked through alkyl chains. A disc-shaped molecule 2,3,6,7,10,11-hexakis-[{4-(4-nitrophenylazo)phenoxy} hexyloxy]triphenylene was prepar
- Rahman, Md. Lutfor,Tschierske, Carsten,Yusoff, Mashitah,Silong, Sidik
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p. 2303 - 2306
(2007/10/03)
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- Polyamidoimides with side chromophoric groups
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A new method was elaborated for the introduction of chromophores into the side chains of polymers by esterification of polyamidoimides containing side carboxy groups with glycidyl ethers of dyes, 4-(4-nitrophenylazo)phenol and 4-(6-nitrobenzothiazol-2-ylazo)phenol. The optimum modification conditions were found that made it possible to esterify 15, 30, 50, and 90% of the carboxy groups. The synthesized polymers possess valuable physicomechanical properties (E = 2.8-3.3 GPa, σu = 69-90 MPa, εu = 38-77%) and glass transition temperatures of 115-125°C, depending on the degree of esterification. After chromophore orientation in the corona discharge, all the polymers demonstrate nonlinear optical properties of the second order.
- Goikhman,Subbotina,Gofman,Yakimanskii,Bursian,Lukoshkin,Fedorova,Sidorovich,Praslova,Smirnov,Abalov,Kudryavtsev
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p. 1481 - 1487
(2007/10/03)
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- Modified clays as efficient acid-base catalyst systems for diazotization and diazocoupling reactions
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Diazotization and diazocoupling reactions of aniline and its substituted derivatives with phenol and other aromatic amines over ecofriendly clay catalysts is described. This inexpensive, non-corrosive and reusable catalysts were found to exhibit bifunctional catalytic properties for these reactions. No considerable decrease in the efficiency of the catalysts were observed after five cycles of operation. The new method totally avoids the use of acids and alkalies.
- Bahulayan, Damodaran,John, Litka,Lalithambika, Malathy
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p. 863 - 869
(2007/10/03)
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- Liquid crystalline properties and orientational structure of binary systems built from poly(vinylalcohol) and amphiphilic compound
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Liquid crystalline binary systems, consisting of poly(vinylalcohol) and an amphiphilic compound with hydrophobic nitroazobenzene and hydrophilic ethyleneimine units, were prepared, and their thermal and liquid crystalline properties were estimated. The amphiphilic compound exhibited a smectic A phase with a focal conic fan texture. The liquid crystalline binary systems showed a thermotropic smectic A mesophase. In the smectic A phase, a smectic layer structure with hydrophobic and hydrophilic sublayers was formed. frnrlinn: thprmnl nrnnprtips 2000 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.
- Ujiie, Seiji,Yano, Yumi
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p. 265 - 272
(2007/10/03)
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- Synthesis of porphyrins with reactive groups on phenyl rings. 8. Azo dyes on tetraphenylporphyrins
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Porphyrins having covalently attached residues of azo dyes on the periphery of the molecule have been synthesized by the diazotization of tetraaminophenylporphyrins and subsequent azo coupling of the diazonium salts with phenol, and with α- and β-naphthols. The possibility of π - π electron interaction of the two chromophoric systems has been studied. 1997 Plenum Publishing Corporation.
- Syrbu,Semeikin,Syrbu
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p. 897 - 901
(2007/10/03)
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- Phase Transitions of Liquid Crystalline Polymethacrylates having 4-(4-Substituted Phenylazo)phenyl Benzoate in a Mesogenic Side Chain
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Two types of liquid crystalline polymethacrylates, having 4-(4-substituted phenylazo)phenyl benzoate in a mesogenic side chain, were prepared.The relationship between the shape of the mesogenic side chain and the liquid crystallinity was studied. - Keywords: liquid crystalline polymethacrylate, nematic, smectic, thermal property, shape of mesogenic side chain
- Ujiie, Seiji,Maekawa, Kazuhiko,Takahashi, Satoshi,Iimura, Kazuyoshi
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p. 477 - 482
(2007/10/02)
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- MECHANISM OF AZO COUPLING. VI. REACTIONS OF THE p-NITROBENZENEDIAZONIUM ION WITH (PHENYLAZO)PHENOL AND ITS DERIVATIVES
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According to the results of elemental analysis, high-performance liquid chromatography, and NMR, UV, and IR spectroscopy the preparatively isolated products of the reactions of the p-nitrobenzenediazonium ion with p-(phenylazo)phenol and its derivatives are derivatives of 4,4-bis(p-nitrophenylazo)-2,5-cyclohexadien-1-one.The products are stable in the solid state and in neutral media.In acid and alkaline media they are split with the formation of the nitrobenzenediazonium ion and the corresponding p-(phenylazo)phenols.The product with a cyclohexadienone structure is regarded as a model of the second of the two successively formed intermediate complexes in the azo coupling.
- Bagal, I. L.,Zul'figarov, O. S.,Yurchenko, V. V.,Trachevskii, V. V.,El'tsov, A. V.
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p. 762 - 767
(2007/10/02)
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- Synthesis and Characterisation of Liquid Crystalline Polymers for Nonlinear Optical Applications
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A series of side chain liquid crystalline polymers based on a polystyrene backbone has been synthesized and characterized for non-linear optical applications.Keywords: liquid crystal polymers, non-linear, optical, polystyrene
- McCulloch, I. A.,Bailey, R. T.
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p. 157 - 166
(2007/10/02)
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- Studies on the Reactivity of Azoxybenzenes. Part 12. αβ-Interconversion of para-Monosubstituted Azoxybenzenes in the Wallach Rearrangement
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Under the reaction conditions for the Wallach rearrangement, 4-methyl-ONN-(1α), 4-methyl-NNO-(1β), 4-nitro-ONN-(2α), and 4-nitro-NNO-azoxybenzene (2β) were found to undergo αβ-interconversion, while 4-bromo-ONN-(3α) and 4-bromo-NNO-azoxybenzene (3β) do not.The αβ-interconversion occurs with both mono- and di-protonated forms of the azoxybenzenes.
- Yamamoto, Jiro,Aimi, Hironori,Masuda, Yasuko,Sumida, Takashi,Umezo, Masahiro,Matuura, Teruo
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p. 1565 - 1568
(2007/10/02)
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- BASIC PROPERTIES OF 4-ARYLAZO-PHENOLS AND 4-ARYLAZO-ANISOLES
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The conditions in which 4-arylazo-phenols and 4-arylazo-anisoles have basic properties have been studied.We have also determined the equilibrium constants of the reactions between 4-arylazo-phenols or 4-arylazo-anisoles with perchloric acid in nitromethane, acetonitrile and acetic acid.Conclusions have been drawn from the influence of the nature of solvent and substituent at the benzene ring on equilibrium constant values.
- Nesterowicz, Marianna,Korewa, Ryszard
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p. 1085 - 1092
(2007/10/02)
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