Novel triazene dyes based on N-phenylpiperazine: Synthesis, anti-bacterial activity and solvatochromic properties

Stable CAAC-Triazenes: A New Nitrogen Ligand System With Donor and Conformational Flexibility, and With Application in Olefin Activation Catalysis

N-heterocyclic imines such as pyridylidene amines impart high catalytic activity when coordinated to a transition metal, largely imposed by their electronic flexibility. Here, this donor flexibility has been applied for the first time to CAAC-based systems through the synthesis of CAAC-triazenes. These new ligands offer a larger π-conjugation that extends from the N-heterocyclic carbene through three nitrogens rather than just one, as observed in N-heterocyclic imines. We demonstrate the straightforward synthesis of three new CAAC-triazenes containing different substituents on the terminal triazene nitrogen. These compounds are remarkably stable up to 120 °C without loss of N2 as typically observed with similar triazenes. E-to-Z isomerization within the triazene is instigated by UV light and is partially reversible dependent on the triazene substituent. The quinoline-substituted CAAC-triazene 1-Q has been applied as an L,L'-type ligand in the synthesis of [PdCl2(1-Q)], [PdCl(Me)(1-Q)] and [Pd(Me)(H2O(1-Q)]+. E-to-Z ligand isomerization also occurs when coordinated to PdCl2, providing access to on-metal manipulation. The cationic complex [PdMe(H2O)(1-Q)]+ is a precatalyst for oligomerization of ethylene to form initially 2-butene and subsequently linear and branched C8-C12 products from butene activation. Moreover, isomerization of 1-hexene takes place efficiently with exceptionally low catalyst loading (10 ppm) and up to 74,000 turnover numbers.

Potential of several triazene derivatives against DENGUE viruses

Dengue fever is an infectious disease caused by the dengue virus (DENV), an RNA Flavivirus transmitted by the mosquitoes Aedes aegypti and Aedes albopictus widespread in tropical, subtropical and also temperate regions. Symptoms range from a simple cold to a severe, life-threatening haemorrhagic fever. According to the WHO, it affects around 390 million people per year. No antiviral treatment for DENV is available, and the Dengvaxia vaccine is only intended for people over 9 years of age who have contracted dengue one time in the past, and shows serotype-specific effectiveness. There is therefore a crying need to discover new molecules with antiviral power against flaviviruses. The present study was carried out to evaluate the anti-DENV activities and cytotoxicity of triazenes obtained by diazocopulation. Some triazenes were highly cytotoxic (16, and 25) to hepatocarcinoma Huh7 cells, whereas others displayed strong anti-DENV potential. The antiviral activity ranged from EC50 = 7.82 µM to 48.12 µM in cellulo, with a selectivity index (CC50/EC50) greater than 9 for two of the compounds (10, and 20). In conclusion, these new triazenes could serve as a lead to develop and optimize drugs against DENV.

Evaluation of the Physicochemical, Antioxidant, and Antibacterial Properties of Tunichrome Released from Phallusia nigra Persian Gulf Marine Tunicate

The aim of this study was to evaluate the physicochemical, nutraceutical, antioxidant, and antibacterial properties of tunichrome released from Persian Gulf tunicate (Phallusia nigra). For this purpose, molecular weight (SDS-PAGE), amino acid profile, chemical composition (GC-MS), mineral composition, functional groups (FTIR), total phenol content (TPC), total flavonoid content (TFC), antioxidant activity, and antimicrobial properties were investigated. The results showed that tunichrome contained a high amount of essential amino acids (i.e., Lys = 32.24 mg/100 g) and essential minerals. According to GC-MS results, tunichrome had different antioxidant and antimicrobial components. The TPC and TFC of tunichrome were 0.55 mg GA/g and 0.21 mg quercetin/100 g, respectively. Tunichrome showed higher antioxidant activity than ascorbic acid, and its radical scavenging activity values were increased from 30.28 to 82.08% by increasing concentration from 50 to 200 ppm. Inhibition zones of Staphylococcus aureus, Bacillus cereus, Salmonella enterica, and Escherichia coli O157:H7 were 14, 18, 17, and 15 mm, respectively. Moreover, the minimum inhibitory concentration values of tunichrome for S. aureus, Bacillus cereus, S. enterica, and E. coli O157:H7 were 1.17, 0.59, 0.59, and 1.17 mg/ml, respectively. The minimum bacterial concentrations were 2.34, 1.17, 1.17, and 2.34 mg/ml for S. aureus, Bacillus cereus, S. enterica, and E. coli O157:H7, respectively. These results showed that tunichrome of Phallusia nigra has excellent biological effects as a bioactive compound for food fortification.

Classifications, properties, recent synthesis and applications of azo dyes

In this work, we have presented a very detailed review of the different classification of azo dyes as a function of the number of azo groups and the appropriate functional groups. Then we pointed out some chemical properties of these dyes such as reactivity, isomerization and tautomerism and listed. In the following, we have summarized some recent syntheses of azo dyes and the mechanism of azo dye/polymer conjugation. Finally, we indicate the principle of Gewald's reaction and its application to the synthesis of new azo dyes.

UV protective heterocyclic disperse azo dyes: Spectral properties, dyeing, potent antibacterial activity on dyed fabric and comparative computational study

Disperse azo dyes are synthesized and characterized by ¹H NMR, ¹³C NMR, LC-MS, Elemental analysis, UV-visible, and fluorescence spectroscopy methods. The azo dyes show absorption maxima in the range of 460-493 nm. Dye with benzothiazole moiety i.e. VM7a and VM8a show a bathochromic shift in absorption maxima of 90 and 26 nm respectively in a polar aprotic solvent (i.e. DMF, DMSO). The dyes show deep red emission in a polar aprotic solvent (i.e. DMF, DMSO) with a Stokes shift of 62 to 180 nm. The dyes are applied on polyester fabric and the dyed fabric exhibit excellent to a good wash and sublimation fastness property. They show a very good UPF rating and almost blocking 95 to 98% of harmful UV radiation. Antibacterial activity of dyed polyester fabric is assessed qualitatively and quantitatively by using AATCC 147 and 100 test method respectively. The dyed fabrics exhibit excellent antibacterial activities against S.aureus (Gram-positive) and K. pneumoniae (Gram-negative). DFT method was used to identify the stable conformer. HOMO-LUMO gap and global reactivity descriptors were calculated using DFT method and correlated with antibacterial activities and light fastness properties respectively.

Mediated electrochemical method for the determination of indigo carmine levels in food products

In this paper, we have studied the electrochemical behavior of indigo carmine (IC) in the presence and absence of mediator molecules. We have used three azo dyes as mediators in our studies and the effect of mediator molecules on the electron transfer between the IC solution and the electrode surface was explained from the cyclic voltammograms data. Among these dyes, 4-(4-nitrophenilazo)N-benzyl,N-ethylaniline (NBE) showed good performance as an electron transfer mediator. The NBE/carbon paste was characterized with Fourier transform infrared spectroscopy and scanning electron microscopy methods. The redox peak currents of IC were enhanced significantly compared with those obtained at the unmodified electrode. Some parameters affecting sensor response were optimized and then the calibration curve was plotted. The oxidation peak current was proportional to the concentration of IC from 1 to 100μmolL^-1. The detection limit was 0.36μmolL^-1. The proposed electrode was successfully applied to the determination of IC in various real samples without complex sample pretreatment.

Piperazine scaffold: A remarkable tool in generation of diverse pharmacological agents

Piperazine is one of the most sought heterocyclics for the development of new drug candidates. This ring can be traced in a number of well established, commercially available drugs. Wide array of pharmacological activities exhibited by piperazine derivatives have made them indispensable anchors for the development of novel therapeutic agents. The review herein highlights the therapeutic significance of piperazine derivatives. Various therapeutically active piperazine derivatives developed by several chemists are reported here.

Novel push-pull heterocyclic azo disperse dyes containing piperazine moiety: Synthesis, spectral properties, antioxidant activity and dyeing performance on polyester fibers

Six novel push-pull azo disperse dyes were synthesized via classical azo coupling reaction using 2-amino-thiazolyl derivatives as the diazo components and 1-(4-bromobenzyl)-4-phenylpiperazine as a key coupling intermediate. The structures of the dyes and synthesized intermediate were confirmed by FT-IR, (1)H NMR, (13)C NMR and UV-vis analyses. The solvatochromic behavior of the dyes was studied in a set of 10 solvents of different polarity and considerable results were obtained. The prepared heterocyclic azo dyes were applied for dyeing polyester fibers and their dyeing properties were studied. The fastness properties of the dyed fabrics such as wash, light and rubbing fastness degrees were measured by standard methods. Investigation of antioxidant activity of compounds was carried out by ferric reducing antioxidant power (FRAP) method. The synthesized dyes exhibited significant antioxidant activities.