- Azo-dyes based small bifunctional molecules for metal chelation and controlling amyloid formation
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Chemical tools are needed to discover new effective drugs for tackling multifaceted complex neurodegenerative diseases like Alzheimer's disease (AD). Multifunctional nature of two compounds, 5-((4-nitrophenyl)diazenyl)quinolin-8-ol (HL1) and 4-((4-nitrophenyl)diazenyl)benzene-1,3-diol (HL2) is reported w.r.t. their ability to bind Cu2+ ions and amyloid aggregates related to AD. HL1 and HL2 have half congo-red type azo-stilbene structural framework incorporated with metal chelating groups, designed to chelate metal ions from metal-amyloid species. Metal binding studies of HL1 and HL2 are established by the methods of Job's Plot, UV-vis spectra with metal ions and stability constant determination. In addition, their metal complexes are isolated, purity checked by elemental analysis, spectroscopically characterized and their structural analyses were obtained from DFT based calculations including binding energy determination. Chicken egg white Lysozyme (CEWL) was used as a model peptide for fibrillation studies. HL1 is found as an excellent colorimetric sensor for amyloid fibrils. Inhibitory effect of HL1 and HL2 and their isolated metal complexes L1-Cu and L2-Cu on CEWL fibrillation was studied using ThT and ANS fluorescence assay along with TEM imaging. In addition, the cell toxicity studies on these compounds suggest that although azo dyes may be non-toxic but having a nitro-substitution lead to significant cell toxicity. Overall, these results suggest that this new class of multifunctional small molecules can interact with amyloids as well as metal ions and could be potential anti-aggregation metal chelating agents.
- Rana, Monika,Cho, Hong-Jun,Roy, Tapta Kanchan,Mirica, Liviu M.,Sharma, Anuj K.
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- Synthesis of nitroso-based bis-azo dyes and their dyeing properties for polyethylene terephthalate and polyamide
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The aim of this work is the synthesis of new azo nitroso-based dispersed dyes with better dyeing properties on synthetic fibers. In this regard, bis-azo nitroso naphthalene dyes were synthesized via the diazo coupling reactions of 4-nitroaniline with 1-hydroxy-2-nitrosonapthalene. Products formed were characterized by 1H and 13C NMR. Absorption values in the UV-vis spectra of the derivatives under study were quite close and they exhibited multiple maxima in the 386 - 513nm range. The dyeing process, dye exhaustion on polyethylene terephthalate (PET) and polyamide 6 (nylon 6) fabrics, and the durability of the dyes on the textile substrates were evaluated. It was found that the light fastness ratings of the dyed fabrics could reach grade 6/7 to 7, while washing fastness gave excellent values of grade 5 rubbing and perspiration fastness grades were rated at 4/5 to 5 on the International Geometric Scale. The results obtained suggested that the dyes could be used as disperse dyes on synthetic polymers fibres.
- Augustine, Asiagwu K.,Otutu, Johnson O.
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p. 3949 - 3959
(2020/11/18)
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- New generation of nitrite functionalized star-like polyvinyl imidazolium compound: Application as a nitrosonium source and three dimensional nanocatalyst for the synthesis of azo dyes
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The compounds with three-dimensional and ionic structures have attracted considerable attentions because of their unique characteristics as a drug carrier and catalyst. Star-like poly ionic compounds are a new generation of three-dimensional structures which have both; the exclusive ionic features and three-dimensional structures. Recently, we reported the synthesis of diazonium salts from aniline derivatives using carboxyl and nitrite functionalized graphene quantum dots. Methods: Nitrite-functionalized star-like polyionic (NFSP) compound was synthesized as a new generation of three-dimensional nanocatalyst. Herein, the use of NFSP as an efficient reagent and nanocatalyst for the diazotization of aniline derivatives and subsequent synthesis of azo dyes via the reaction with active phenolates under solvent-free conditions was reported. Results: In order to demonstrate the positive impact of NFSP efficiency, the reaction times and yields of the products were compared with other methods and catalysts which have been reported previously. The brilliant performance of NFSP can be ascribed to multifunctional reagent and also trapping the ingredient within catalyst cavities. Conclusion: A highly effective and cost-effective method has been developed for the preparation of azo dyes. In reported method, new three-dimensional catalyst with highly ionic characteristic and multifunctional nitrosonium source is available. These special features reduced the required amount of catalyst, reaction time and also increased the efficiency of catalyst.
- Shomali, Ashkan,Valizadeh, Hassan,Noorshargh, Saeideh
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p. 409 - 418
(2017/07/24)
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- Convenient and rapid diazotization and diazo coupling reaction via aryl diazonium nanomagnetic sulfate under solvent-free conditions at room temperature
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For the first time, nanomagnetic-supported sulfonic acid is used for conversion of several types of aromatic amine, containing electron-withdrawing groups as well as electron-donating groups to the corresponding azo dyes in excellent yield. The synthesis of these compounds is described by the sequential diazotization-diazo coupling of various aromatic amines with sodium nitrite, nanomagnetic supported sulfonic acid and coupling agents under solvent-free conditions at room temperature. This new method offers several advantages including short reaction time, mild reaction conditions, avoidance of harmful acids, and simple work-up procedure. More importantly, aryldiazonium salts supported on magnetic nanoparticles (aryl diazonium nanomagnetic sulfate) were sufficiently stable to be kept at room temperature in the dry state.
- Koukabi, Nadiya,Otokesh, Somayeh,Kolvari, Eskandar,Amoozadeh, Ali
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- Synthesis of a nitrite functionalized star-like poly ionic compound as a highly efficient nitrosonium source and catalyst for the diazotization of anilines and subsequent facile synthesis of azo dyes under solvent-free conditions
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Nitrite functionalized star-like poly ionic (NFSPI) compound was synthesized and used as a highly efficient nitrosonium source and catalyst for the conversion of aniline derivatives to diazonium salts. Azo dyes were prepared via in situ azo-coupling reaction of these diazoniums with active aromatic compounds under solvent-free conditions in very short reaction time in excellent yields. NFSPI plays dual role as a three-dimensional nitrosonium source and catalyst because of its poly ionic characteristic. The isolated products were confirmed with FT-IR spectrum, 1H-NMR, 13C-NMR spectroscopy and CHNSO analysis. The structure of heterogeneous reagent and catalyst was confirmed by FT-IR spectrum, SEM images, EDX and CHNSO analysis. Yields and reaction times for the synthesis of a variety of products via this procedure were compared with reported values in literature.
- Valizadeh, Hassan,Shomali, Ashkan,Ghorbani, Jalal,Noorshargh, Saeideh
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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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- 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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- 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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- 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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experimental part
p. 495 - 501
(2012/07/13)
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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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- Synthesis and application of 2-nitro-2′,4′-dihydroxyazobenzene, 4-nitro-2′,4′-dihydroxyazobenzene and 2-carboxy-2′- hydroxyazonaphthol for dyeing of jute fabric
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The following three azo dyes namely, 2-nitro-2′,4′- dihydroxyazobenzene (I), 4-Nitro-2′,4′-dihydroxyazobenzene (II) and 2-carboxy-2′-hydroxyazonaphthol (III) have been synthesized and characterized. These three azo dyes have been successfully applied for dyeing of bleached jute fabric in alkaline medium following the conventional exhaust method. The performance of the dyes are evaluated by evaluating the colour yield and wash fastness of the dyed fabric samples'.
- Sarkhel, Jayanta,Chattopadhyay,Bhaduri,Deb, Tathagata,Pandey, Kalyan,Saha
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p. 1020 - 1023
(2008/12/21)
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- Synthesis and Characterization of Models for the 2,4,5-Trihydroxyphenylalanine (TOPA)-Derived Cofactor of Mammalian Copper Amine Oxidases, and Initial Amine Reactivity Studies
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The mammalian copper amine oxidases effect the oxidative deamination of primary amines through utilization of an "active carbonyl" cofactor, shown recently to be the quinone form (TPQ) of a protein-based 2,4,5-trihydroxyphenylalanine (TOPA) residue.We synthesized three models for the cofactor in both reduced (benzenetriol) and oxidized (hydroxyquinone) forms, which differ in the nature of the alkyl substituent mimicking the connection to the protein backbone: hydantoinylmethyl, phthalimidoethyl, and pivalamidoethyl.The quinone forms were capable of deaminating benzylamine in aqueous CH3CN both stoichiometrically and catalytically (in the presence of O2), but incapable of deaminating non-benzylic amines.In order to clarify the various reactions potentially occurring during aerobic autorecycling deamination, we studied the pH-dependent benzenetriol -> hydroxyquinone autoxidation as well as the possible reaction of amines with the benzenetriol forms.The latter undergo stoichiometric substitution with amines to give (alkylamino)resorcinols, not via cyclohexadienone tautomerization previously proposed, but via a redox cycling mechanism involving condensation of the amines with traces of hydroxyquinone present in the benzenetriol preparations.This observed substitution regiochemistry, as well as structural characterization of the hydroxyquinone arylhydrazine derivatives, confirms that amines react exclusively at the electrophilic C5 carbonyl position of TPQ models.Both the hydroxyquinone and benzenetriol forms were found to react with ethylenediamine in the presence of O2 to give 6-hydroxy-7-(2-pivalamidoethyl)quinoxaline, consistent with the postulated generation of such moiety when lysyl oxidase is inactivated by ethylenediamine.
- Wang, Fengjiang,Bae, Jin-Young,Jacobson, Alan R.,Lee, Younghee,Sayre, Lawrence M.
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p. 2409 - 2417
(2007/10/02)
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- A Simple Route for the Synthesis of Chlorosubstituted Arylazobenzenes, Arylazonaphtalenes, and Arylazopyrazoles
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The reaction of arylazophenoles and arylazohydroxypyrazoles (or their tautomer hydrazones) 10, 11, and 15 with POCl3 in dimethylformamide yields chlorosubstituted arylazobenzenes or arylazopyrazoles 12, 13 and 16, resp., in moderate to high yields.The substitution of the OH-group by the Cl-moiety is favoured by acceptor substituents in the aryl fragments ortho- and/or para-linked to the azo group.In case that arylazocompounds derived from resorcinol are used the substitution reaction runs in a stepwise manner giving raise to the formation of o-hydroxy-p-chlorosubstit uted azo compounds 18 primarily and then of dichlorosubstituted azo compounds 19.
- Guenther, R.,Jaehne, E.,Hartmann, H.,Schulze, M.
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p. 945 - 954
(2007/10/02)
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