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AbstractThe compound 6-fluoro-4-hydroxyquinolin-2(1H)-one (1) was synthesized and reacted with diazotized 2, 4-dimethylaniline in a basic medium, yielding the hydrazone derivative (2) as a deep yellow crystalline compound. The structure of the purified product was confirmed through FT-IR, 1D and 2D NMR, and mass spectroscopic analyses. The results showed that the product exclusively adopts a hydrazone structure, existing as an equilibrium mixture of E and Z geometrical isomers in solution. DFT quantum calculations at the B3LYP/6-311++G (d, p) level indicated that the hydrazone form of compound (2) is more stable than the proposed azo structure, with the Z-hydrazone isomer having the lowest total energy. Additionally, UV-Vis spectroscopy studies of the E and Z isomers of hydrazone compound (2) in solvents of varying polarities showed that the E isomer is the predominant species in non-polar solvents. [ABSTRACT FROM AUTHOR]

Azo coupling reactions of (Z)-2-(3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)ylidene)-N-(2,4-xylyl)-acetamide with diazonium salts were used to synthesize 2-(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)-2-(2-arylhydrazono)-N-(2,4-xylyl)-acetamides. All compounds showed analgesic effects in the hotplate test, exceeding the effect of metamizole sodium. In the case of the most active hydrazone, the defensive reflex time in mice was 27.10 min (compared with 16.60 min for metamizole sodium). [ABSTRACT FROM AUTHOR]

A highly sensitive, selective and recyclable histidine detection method based on magnetic Fe3O4@mTiO2 (M-TiO2) nanocomposites with SERRS was developed. Mesoporous M-TiO2 nanoparticles were functionalized with 4-aminothiophenol and then coupled with histidine through an azo coupling reaction in 5 min, producing the corresponding azo compound. The strong and specific SERRS response of the azo product allowed for ultrasensitive and selective detection for histidine with an M-TiO2 device loaded with Ag NPs due to the molecular resonance effect and plasmonic effect of Ag NPs under a 532 nm excitation laser. The sensitivity was further enhanced with the magnetic enrichment of M-TiO2. The limit of detection (LOD) was as low as 8.00 × 10−12 mol/L. The M-TiO2 demonstrated applicability towards histidine determination in human urine without any sample pretreatment. Additionally, the M-TiO2 device can be recycled for 3 cycles with the photodegradation of the azo product under UV irradiation due to TiO2-assisted and plasmon-enhanced photocatalysis. In summary, a multifunctional and recyclable M-TiO2 device was synthesized based on azo coupling and SERRS spectroscopy for ultra-sensitive and specific histidine sensing. In addition, the proposed system demonstrated the potential for the multiplex determination of toxic compounds in the fields of food safety, industrial production and environmental protection, which benefit from the fingerprint property and universality of SERRS. [ABSTRACT FROM AUTHOR]

The behavior of N-Substituted 3,5-dimethyl-4-nitroso-1H-pyrazoles in oxidation, condensation, and reduction reactions was studied. The synthesized 4-aminopyrazole was acylated and diazotized with further azo coupling or the replacement of the amino group by iodine, as well as subjected to condensation with 4-nitrobenzaldehyde. The first condensation of nitrosopyrazole with 2,4-dinitrotoluene was demonstrated. As a result, new functionalized pyrazole derivatives were isolated. The structure of the novel pyrazoles was confirmed by IR and 1H and 13C NMR spectroscopy, gas chromatography-mass spectrometry, and elemental analysis. The synthesized compounds hold promise for further research in medicine and pharmaceutical chemistry. [ABSTRACT FROM AUTHOR]

An efficient protocol for the synthesis of fluorescent 4‐amino‐1,3′‐bipyrazoles, which are substituted at the positions N‐1′, C‐4′, C‐3 and C‐5, is described. By a two‐step synthetic strategy, an initial azo coupling of ethyl cyanoacetate and various 1‐alkylpyrazolyldiazonium chlorides gave substituted ethyl 2‐cyano‐2‐(2‐(pyrazol‐3‐yl)hydrazine‐ylidene)acetates, which were subsequently subjected to Thorpe‐Ziegler type cyclisation reactions to yield the title compounds. [ABSTRACT FROM AUTHOR]

A highly sensitive, selective and recyclable histidine detection method based on magnetic Fe3O4@mTiO2 (M-TiO2) nanocomposites with SERRS was developed. Mesoporous M-TiO2 nanoparticles were functionalized with 4-aminothiophenol and then coupled with histidine through an azo coupling reaction in 5 min, producing the corresponding azo compound. The strong and specific SERRS response of the azo product allowed for ultrasensitive and selective detection for histidine with an M-TiO2 device loaded with Ag NPs due to the molecular resonance effect and plasmonic effect of Ag NPs under a 532 nm excitation laser. The sensitivity was further enhanced with the magnetic enrichment of M-TiO2. The limit of detection (LOD) was as low as 8.00 × 10−12 mol/L. The M-TiO2 demonstrated applicability towards histidine determination in human urine without any sample pretreatment. Additionally, the M-TiO2 device can be recycled for 3 cycles with the photodegradation of the azo product under UV irradiation due to TiO2-assisted and plasmon-enhanced photocatalysis. In summary, a multifunctional and recyclable M-TiO2 device was synthesized based on azo coupling and SERRS spectroscopy for ultra-sensitive and specific histidine sensing. In addition, the proposed system demonstrated the potential for the multiplex determination of toxic compounds in the fields of food safety, industrial production and environmental protection, which benefit from the fingerprint property and universality of SERRS.

A new azo compound was synthesized via an azo coupling reaction between 4-(phenyldiazenyl)benzenediazonium chloride and 8-hydroxyquinoline (8-Hq). The new diazene compound can be used to synthesize metal complexes as a derivative of 8-Hq. The structure of the new compound was characterized using UV–Vis, FT-IR, and 2D NMR spectroscopic methods. [ABSTRACT FROM AUTHOR]

One-pot reaction of 2-phenyloxazol-5(4H)-one with diazonium salts of substituted anilines obtained by direct and reversed diazotization afforded of 2-phenyloxazol-5(4H)-one arylhydrazones, capable of existing as E- and Z-isomers. The equilibrium of neutral and deprotonated forms of the hydrazones in neutral and basic media was studied. The antimicrobial activity of 2-phenyloxazol-5(4H)-one arylhydrazones against Gram-positive and Gram-negative bacteria was evaluated. The inhibitory activity of the compounds under study was shown for test bacterial cultures, which indicated a potential possibility of their use as antimicrobial agents. [ABSTRACT FROM AUTHOR]

A new azo compound was synthesized via an azo coupling reaction between 4-(phenyldiazenyl)benzenediazonium chloride and 8-hydroxyquinoline (8-Hq). The new diazene compound can be used to synthesize metal complexes as a derivative of 8-Hq. The structure of the new compound was characterized using UV–Vis, FT-IR, and 2D NMR spectroscopic methods.

Coupled with an azo coupling reaction, a simple, rapid, sensitive, and effective surface-enhanced resonance Raman scattering (SERRS) detection method for benzocaine was developed. In our study, benzocaine which is used clinically as a local anesthetic was derived with p-aminothiophenol into a corresponding azo product within 5 min, resulting in a strong SERRS response with the simple addition of Ag NPs excited with a 532 nm laser. The linear correlation between SERRS intensity of dominant bands and logarithm of benzocaine concentration was investigated for quantitative determination. The method reached a limit of detection (LOD) down to 0.139 and 0.0788 μg/mL calculated with two peak intensity ratios (I1568/I2260 and I1331/I2260), which is comparable to most studies reported previously, and meanwhile had superiority in simplicity and rapidness. The quantitative measurements for pharmaceutical preparations with benzocaine were conducted without complex extraction and enrichment processes. It was indicated that the SERRS assay combined with azo derivatization reaction has implications for practical applications in more complicated systems involving biological samples, in which appropriate and simplified pretreatments were conducted to remove interfering components. [ABSTRACT FROM AUTHOR]

Because of its anti‐inflammatory properties, 5‐aminosalicylic acid (5‐ASA) is used in medicines for intestinal diseases such as: Crohn′s disease and ulcerative colitis. This compound is contained in unchanged form in enteric‐coated tablets to prevent early absorption and subsequent metabolism. Another strategy is pursued with the prodrug concept: For this, 5‐ASA is converted into azosalicylic acid, a stable compound without its own biological activity. This compound is then broken down into active 5‐ASA molecules in the intestine by bacterial azoreductases. The present article takes a look at the interesting development history of azosalicylic acid. Afterwards, extensive suggestions (concept, experiments, models) are given for implementing this interdisciplinary topic in chemistry lessons of secondary level. [ABSTRACT FROM AUTHOR]

A rapid, simple and sensitive spectrophotometric method for the determination of amoxicillin (AM) is described. The method is based on the previous sulphanilamide (SA) and sulphathiazole (STZ) diazotization in the medium of 0.6–0.7 M hydrochloric acid and their subsequent interaction with amoxicillin at pH = 10.5 with formation of yellow-colored azo compouds. Effective molar absorptivities at the absorbance maxima at 445 nm (SA) and 448 nm (STZ) for azo compounds were (1.74 ± 0,06)∙104 L×mol-1×cm-1 and (1.97 ± 0,05)∙104 L×mol-1×cm-1, respectively. Stoichiometric ratios of the components of azo compounds were determined using continuous variations method. Based on the optimum reaction conditions, new methods were developed. These methods allow to determine the amoxicillin in concentration range 1.3–32.9 mg×mL-1 with sulphanilamide and 0.7–27.4 mg×mL-1 with sulphathiazole. The methods were successfully validated for amoxicillin determination in tablets “Amoxil”.

We improved the synthetic procedure for 3-(2-arylhydrazono)-1,1,1-trifluro-3-(phenylsulfonyl)propan-2-ones and established their structure. The study of their esterase profile showed the absence of cholinesterase inhibition and the selectivity against carboxylesterase with micromolar activity exceeding the anticarboxylesterase activity of the diketone analog. Carboxylesterase inhibition data are consistent with molecular docking results. 3-(2-Arylhydrazono)-1,1,1-trifluro-3-(phenylsulfonyl)propan-2-ones exhibit a high radical-scavenging effect in the ABTS test exceeding that of Trolox. [ABSTRACT FROM AUTHOR]

The novel method of amoxicillin (AM) determination has been developed using single‐sweep polarography. The proposed method is based on the obtaining of yellow coloured azo compound due to azo coupling reaction of previous diazotized sulphanilamide (SA) (in the medium of 0.6 M hydrochloric acid) with amoxicillin at pH=9.0 with the further reduction of the formed analytical form on a dropping mercury electrode. Voltammetric determination of amoxicillin is carried out due to the reduction peak of azo group of the obtained azo compound in the presence of 0.05 mol ⋅ L−1 Na2B4O7 as a background electrolyte at the potential Ecp2=−0.55 V and potential sweep rate of 2.5 V ⋅ s−1. The developed voltammetric method has two linear ranges of the determined concentrations (0.05–2.0) ⋅ 10−5 mol ⋅ L−1 and (0.2–1.0) ⋅ 10−4 mol ⋅ L−1 and the high sensitivity: LOD without the removing of unreacted sodium nitrite is 1.1 ⋅ 10−6 mol ⋅ L−1, and 7.2 ⋅ 10−7 mol ⋅ L−1, when NaNO2 excess is removed using urea. The developed voltammetric technique of AM determination has been approved during the analyses of tablets and oral suspension. [ABSTRACT FROM AUTHOR]

A conjugate of erythropoietin β with 30 kDa linear methoxy poly(ethylene glycol) characterized by the presence of an azo spacer between the protein fragment and poly(ethylene glycol) was developed for import-substitution of Mircera drug in the Russian Federation. The erythropoietic activity of the synthesized conjugate was determined. Its pharmacokinetics in CBA mice were found to be comparable to those of Mircera. The bioequivalence of the proposed azo conjugate and Mircera was established based on the calculated drug pharmacokinetic parameters in mice. [ABSTRACT FROM AUTHOR]

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1′-Aminocobaltocenium-1-carboxylic acid chloride, [Co(C5H6N)(C6H5O2)]Cl·H2O, (3), and its azo derivative 1′-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carboxylic acid hexafluoridophosphate, [Co(C13H14N3)(C6H5O2)]PF6·H2O (5) were obtained from cobaltocenium-1,1′-dicarboxylic acid hexafluoridophosphate by converting one carboxyl group to its chlorocarboxyl derivative followed by chloride/azide exchange, Curtius rearrangement, diazotiation and azo coupling with 2,6-dimethylaniline. Both title compounds crystallize as their monohydrates. In the crystal structure of 3, both functional groups lie in the same direction, with the Cp rings being nearly eclipsed, and participate in an extended hydrogen-bonded supramolecular network including the counter-ion and the water molecule of crystallization. Although the functional groups in 5 are somewhat further apart, bearing a greater torsion angle with the Cp rings now staggered, a similar supramolecular network is observed with not only the carboxylic acid and azo groups, but also with the more remote amino group participating in a hydrogen-bonded network, again including the counter-ion and the water molecule. The hexafluoridophosphate ion shows positional disorder. Compound 3 was refined as an inversion twin. In 5, each of the six F atoms is disordered over two sets of sites in a 1:1 ratio.

A new azo compound was prepared via the azo coupling reaction between 4-(ethoxycarbonyl)-3-methyl-1H-pyrazole-5-diazonium chloride and 8-hydroxyquinoline (oxine). The ester functional group of the obtained compound was hydrolyzed and thus a new chemical structure with a carboxylic functional group resulted. The structures of the new compounds were fully characterized by: UV–Vis, FT-IR, 1D and 2D NMR spectroscopy, and HRMS spectrometry.

A number of polydentate diazoarylcelluloses have been proposed in the form of reagent indicator, in which the functional diazo group is connected to the rest of the molecule through fragments of crown ether. When azo coupling of diazoaryl celluloses with amino and hydroxy aryl compounds having an azo coupling active in the molecule, a coordination cavity was formed, the denticity of which was increased due to donor atoms of the formed azo group and the adjacent ortho substituent from the azo component. This led to the formation of polydentate chelants, few differing in color, but in the presence of one or another metal ion—to the formation of their complexes, significantly differing from each other in color characteristics and electronic absorption and diffuse reflection spectra. Examples of selective chromogenic reactions of diazoarylcelluloses with 2-naphthol with the participation of gold(III) in a mixture of structurally similar substances and with 2,4-xylidine with the participation of cobalt(II) in a mixture of 6 isomeric xylidines are given. [ABSTRACT FROM AUTHOR]

Coupled with an azo coupling reaction, a simple, rapid, sensitive, and effective surface-enhanced resonance Raman scattering (SERRS) detection method for benzocaine was developed. In our study, benzocaine which is used clinically as a local anesthetic was derived with p-aminothiophenol into a corresponding azo product within 5 min, resulting in a strong SERRS response with the simple addition of Ag NPs excited with a 532 nm laser. The linear correlation between SERRS intensity of dominant bands and logarithm of benzocaine concentration was investigated for quantitative determination. The method reached a limit of detection (LOD) down to 0.139 and 0.0788 μg/mL calculated with two peak intensity ratios (I1568/I2260 and I1331/I2260), which is comparable to most studies reported previously, and meanwhile had superiority in simplicity and rapidness. The quantitative measurements for pharmaceutical preparations with benzocaine were conducted without complex extraction and enrichment processes. It was indicated that the SERRS assay combined with azo derivatization reaction has implications for practical applications in more complicated systems involving biological samples, in which appropriate and simplified pretreatments were conducted to remove interfering components.

4-Ethoxycarbonyl(cyano)-1,3-dimethyl-β-carbolines were synthesized via thermolysis of 4-aryl-3(5)-azidopyridines and their optical and hypoglycemic properties were studied. For the first time, the accessible Hantzsch nitropyridines were used as the starting materials. Diazotization of 3-aminopyridines having a trimethoxyaryl substituent at the C-4 position of the pyridine ring by intramolecular azo coupling afforded 7,8,9-trimethoxy-2,4-dimethylpyrido[3,4-c]cinnolines. When evaluating the hypoglycemic properties of the four obtained β-carbolines, it was found that ethyl 7-fluoro-1,3-dimethyl-9H-pyrido[3,4-b]indole-4-carboxylate, the structure of which contains the fluorine atom, has the highest glucose-lowering action. [ABSTRACT FROM AUTHOR]

Green synthesis methods are considered as a safer alternative to the conventional synthetic processes due to their eco-friendly nature, cost-effectiveness, and easy handling. In the present study, an eco-friendly and sustainable method for the synthesis of stable arenediazonium has been developed using saccharin as a cheap and mild acidic agent and tert-butyl nitrite as a diazotization reagent for the first time. These stable intermediates were used in the azo coupling reaction with 4-hydroxybenzaldehyde via telescoped dediazotization. The current method has advantages such as reduced waste by avoiding solvent for the purification of intermediate in diazotization step, cost-effectiveness, simple experimental procedure, good yield of azo dyes, metal-free waste, and environmentally benign conditions. An interesting aspect of this study is the recovery of saccharin from the reaction, which could be reused.

The review summarizes and analyzes data from modern information sources on the methods of synthesis of azolo[X,Y-c][1,2,4]triazines. Approaches to the construction of the condensed azolotriazine heterocyclic system are considered and classified, the conditions of the synthetic processes, the structures and yields of the resulting products are given, and their biological action is described. [ABSTRACT FROM AUTHOR]

Nineteen organoselenides were synthesized and tested for their intrinsic cytotoxicity in hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF-7) cell lines and their corresponding selective cytotoxicity (SI) was estimated using normal lung fibroblast (WI-38) cells. Most of the organic selenides exhibited good anticancer activity, and this was more pronounced in HepG2 cells. Interestingly, the naphthoquinone- (5), thiazol- (12), and the azo-based (13) organic selenides demonstrated promising SI (up to 76). Furthermore, the amine 4c , naphthoquinone 5 , and azo-based 13 and 15 organic selenides were able to down-regulate the expression of Bcl-2 and up-regulate the expression levels of IL-2, IL-6 and CD40 in HepG2 cells compared to untreated cells. Moreover, most of the synthesized candidates manifested good free radical-scavenging and GPx-like activities comparable to vitamin C and ebselen. The obtained results suggested that some of the presented organoselenium candidates have promising anti-HepG2 and antioxidant activities. Image 1 • Nineteen organoselenides were synthesized. • Cytotoxicity was evaluated in HepG2 and MCF-7 cell lines. • Selective cytotoxicity was estimated using normal WI-38 cells. • Compounds modulated the expression of Bcl-2, IL-2, IL-6 and CD40 in HepG2 cells. • Redox profiles were estimated employing ABTS, DPPH, and GPx-like activity assays. [ABSTRACT FROM AUTHOR]

The azo coupling of arenediazonium chlorides with (Z)-2-(3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene)-N-(4-methylphenyl)acetamide afforded (Z)-2-(2-arylhydrazinylidene)-2-(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)-N-(4-methylphenyl)acetamides whose structure was confirmed by 1H NMR and X-ray diffraction data. The azo coupling products containing no p-tolyl substituent on the amide nitrogen atom exist in solution as mixtures of azo and hydrazone tautomers. Electronic absorption spectra of the synthesized compounds were studied. [ABSTRACT FROM AUTHOR]

Herein, a strategy for the selective derivatization of 3‐nitrotyrosine‐containing proteins using the classic azo coupling reaction as the key step is described. This novel approach featured multiple advantages and was successfully applied to detect picomole levels of protein tyrosine nitration in biological samples. [ABSTRACT FROM AUTHOR]

A new approach for the synthesis and reactivity of the 1,2,5‐oxadiazolyl diazonium salts is represented. A simple and direct protocol to previously inaccessible furoxanyl and furazanyl diazonium salts was developed for the first time. Azo coupling reactions of thus obtained diazonium salts with a series of structurally diverse CH‐acids have been also successfully performed. Therefore, this study reveals new horizons for the use of furoxanyl and furazanyl diazonium salts in organic chemistry. [ABSTRACT FROM AUTHOR]

1'-Aminocobaltocenium-1-carboxylic acid chloride, [Co(C5H6N)(C6H5O2)]Cl·-H2O, (3), and its azo derivative 1'-[2-(1-amino-2,6-dimethylphenyl)diazen-1-yl]cobaltocenium-1-carboxylic acid hexafluoridophosphate, [Co(C13H14N3)-(C6H5O2)]PF6·H2O (5) were obtained from cobaltocenium-1,10-dicarboxylic acid hexafluoridophosphate by converting one carboxyl group to its chlorocarboxyl derivative followed by chloride/azide exchange, Curtius rearrangement, diazotiation and azo coupling with 2,6-dimethylaniline. Both title compounds crystallize as their monohydrates. In the crystal structure of 3, both functional groups lie in the same direction, with the Cp rings being nearly eclipsed, and participate in an extended hydrogen-bonded supramolecular network including the counter-ion and the water molecule of crystallization. Although the functional groups in 5 are somewhat further apart, bearing a greater torsion angle with the Cp rings now staggered, a similar supramolecular network is observed with not only the carboxylic acid and azo groups, but also with the more remote amino group participating in a hydrogen-bonded network, again including the counter-ion and the water molecule. The hexafluoridophosphate ion shows positional disorder. Compound 3 was refined as an inversion twin. In 5, each of the six Fatoms is disordered over two sets of sites in a 1:1 ratio. [ABSTRACT FROM AUTHOR]

• Development of azo coupling based impedimetric sensors for TCS. • Electrochemical characterization of SAMs using CV and EIS. • Surface reactions were validated through UV-visible, FTIR, NMR and FESEM-EDX. • EIS sensors exhibited wide linear range, low LODs and excellent selectivity. • TCS content was successfully analysed in real samples. Extensive use of triclosan (TCS) in commercially available personal and health care products has led to its abundance in environment (water, soil), resulting in adverse impact on aquatic, marine, animal and human life. The present work is intended towards the development of simple and fast electrochemical sensors for trace level detection of TCS in aqueous media. The working of sensors is based on surface diazotization of self-assembled monolayers (SAMs) of two aminothiols, 4-aminothiophenol (4-ATP) and 5-amino-2-mercaptobenzimidazole (AMB) on polycrystalline gold electrodes. Using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), self-assembly of two aminothiols was confirmed as both offered significant impedance to [Fe(CN) 6 ]3-/4− redox probe. The exposed amino groups of two self-assembled aminothiols were subjected to diazotization and diazo derivatives so formed were utilized as platform for impedimetric sensing of TCS through azo coupling. The step-by-step study of self-assembly, diazotization and azo coupling was conducted using different techniques such as FTIR, UV-visible, NMR, FESEM and EDX. The proposed ATP and AMB based EIS sensors exhibited sensitivity towards TCS in wide linear concentration range of 1.0 × 10-10 M – 1.0 × 10-2 M and 1.0 × 10-12 M – 1.0 × 10-4 M with lower detection limits of 5.6 × 10-11 M and 7.9 × 10-13 M, respectively. A good selectivity was observed in the presence of common metal ions (Na+, K+, Ca2+, Mg2+, Cu2+, Fe3+, Zn2+, Co2+) and surfactants (SDS, Triton X-100, Triton X-114). Using proposed EIS sensors, the estimation of TCS in personal care products (soap, facewash, handwash) and water samples (surface and groundwater) has been successfully achieved. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a micro-fluidic optimized process for the continuous flow synthesis of azo compounds is presented. The continuous flow synthesis of Sudan II azo dye was used as a model reaction for the study. At found optimal azo coupling reaction temperature and pH an investigation of the optimum flow rates of the reactants for the diazotization and azo coupling reactions in Little Things Factory-MS microreactors was performed. A conversion of 98% was achieved in approximately 2.4 minutes and a small library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic systems. The scaled up synthesis of these compounds in PTFE tubing (i.d. 1.5 mm) was also investigated, where good reaction conversions ranging between 66–91% were attained.

The test method of determination of the pyridoxine (vitamin B 6) containing hydroxyaryl group comprises its azo coupling with chromogenic indicator diazo test strip, a reagent with functional diazoaryl group attached to the cellulose carrier through 1,3-diphenoxypropane bridge. This test strip reaction affords cellulose-tethered tetradentate chelating agent capable of forming chromogenic blue-violet complex with CuII ion. [ABSTRACT FROM AUTHOR]

Medicinal Chemistry is a multidisciplinary discipline and the discovery of new bioactive molecules is one of its objectives. Molecular Hybridization (MH) is a strategy of rational design of new prototypes, where the lead compound is produced through an adequate fusion of pharmacophoric sub-unities. Undergraduate laboratory experiments for Medicinal Chemistry education with a focus on MH are scarce. Therefore, the present paper describes a practice class for some undergraduate courses (Pharmacy, Chemistry and/or Chemical Engineering) involving drug development and MH that can be performed at low cost. In this work, alternative materials such as paracetamol and sulfadiazine tablets were used to engage student's attention and to contextualize important concepts of MH. The experiment describes the synthesis of a new compound involving the azo coupling between an aromatic amine (sulfadiazine) and a phenol (paracetamol) to show undergraduate students a practical example of MH. In this case, SciFinder® - a search website of the American Chemical Society - was also demonstrated and utilized as a search tool in the proposed experimental class.

A comparative analysis of physicochemical properties and reactivity of 3-aryl-1H-pyrazole-5-diazonium tetrafluoroborates and 5-aryl-3-diazo-3H-pyrazoles in azo coupling reactions is presented. It is shown that diazonium salts have higher reactivity compared to the respective 3-diazopyrazoles, which is in agreement with their physicochemical properties. Heterocyclization of the synthesized azo compounds provided 2-arylpyrazolo[5,1-c][1,2,4]benzotriazines, which were screened for antitumor activity against human uterine endothelium cancer cells (HeLa cell line) and human skin fibroblasts using the MTT assay and flow cytometry. It was found that all of the tested compounds exhibited moderate to high cytotoxic activity. The best results were obtained with 6,8-dimethoxy-2-phenylpyrazolo-[5,1-c][1,2,4]benzotriazine. [ABSTRACT FROM AUTHOR]

Phenolic compounds, including nitro- and chlorophenols, in neutral aqueous solutions react with diazotized sulfanilic acid. The molecular absorption coefficients of azo dyes obtained from various phenols in the range 360‒380 nm are quite close, which ensures the determination of the total concentration of phenols as C6H5OH. Under optimized conditions, the systematic errors in the analysis of model mixtures did not exceed 30 rel. %. They may be due to either the difference in molar absorption coefficients, or the delayed formation or instability of some azo dyes, and also due to the influence of reducing agents and arylamines. The procedure may become a good alternative to the determination of the phenolic index of sewage waters by the reaction with 4-aminoantipyrine. [ABSTRACT FROM AUTHOR]

Arylhydrazones of 2,3,5,6,7,8-hexahydroacridin-4(1H)-ones and 7-amino-6-(arylhydrazono)-7-oxoheptanoic acids were cyclized by Fischer reaction, providing previously unknown polysubstituted indole derivatives. The starting hydrazones were synthesized under Japp-Klingemann reaction conditions by using 1,2,3,4,5,6,7,8-octahydroacridine-4-carboxamide and 2-oxocyclohexanecarboxamide as starting materials. It was established from the spectral data that the obtained 7-amino-6-(arylhydrazono)-7-oxoheptanoic acids existed as mixtures of (Z)- and (E)-isomers, but were converted to an individual (Z)- or (E)-isomer in DMSO solution. [ABSTRACT FROM AUTHOR]

We report a simple, highly sensitive Bisphenol A (BPA) sensor using BPA-responsive gold nanoparticles (AuNPs) as optical probes. A diazonium carrying ligand was synthesized to self-assemble a monolayer film on AuNPs with the diazonium ions exposed on their surface. One BPA can generate two azobenzene moieties with two diazonium ions via an azo coupling reaction. Thus it can crosslink AuNPs, and induce their aggregation and color change. The BPA concentration-dependent color and UV absorption spectra changes of AuNPs provide the visualization or UV absorption detection of BPA with a fast response (4 min), a broad linear range (0.1–4 nM) and a low limit of detection (0.02 nM ) . [ABSTRACT FROM AUTHOR]