Complexes derived from 4-amino-3-methyl-5-thione-1,2,4-triazole and monoorganomercury moieties. Crystal structure of (4-amino-5-mercapto-3-methyl-1,2,4-triazolato)methylmercury(II)

The compounds [HgR(L)] (R = Me or Ph; L = 4-amino-5-mercapto-3-methyl-1,2,4-triazolate) have been prepared and the crystal structure of the methylmercury(II) compound determined. This compound crystallizes in the monoclinic space group P21/n with a = 5.087(1), b = 10.102(1), c = 16.167(2) Å, β = 98.56(1)°, Z = 4 (R = 0.027; R_w = 0.030). It is formed of molecules in which the triazolate anion is bound to mercury strongly via the S atom and weakly via the amine N; there is also a weak intermolecular interaction between the endocyclic N and the Hg atom of a neighbouring unit.     

Condensed systems based on 4-amino-3-mercapto-1,2,4-triazole

1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazines, hydrazones, and -thio adducts were obtained by reactions of 4-amino-3-mercapto-1,2,4-triazole with -bromoacetophenones, aldehydes, and ,-unsaturated ketones. Conditions that promote the cyclocondensation of the -thio adducts to the previously undescribed 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazepines were found. The chemical and spectral properties of the compounds obtained are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 267–272, February, 1992.     

Pt(II) complexes of 4-amino-4H-1,2,4-triazole

The coordination ability of 4-amino-4H-1,2,4-triazole with Pt(II), both in solution and solid states, is elucidated by conventional and linear-polarized IR spectroscopy of oriented colloid suspensions in nematic host, ¹H- and ¹³C-NMR, UV-Vis spectroscopy, mass spectrometry (ESI and FAB), TGV, and DSC methods. The interpretation of the spectroscopic characteristics of corresponding metal complexes is obtained by comparison with free 4-amino-4H-1,2,4-triazole. In addition, quantum chemical calculations of the last compound are performed to obtain data for electronic structures and optical properties of the ligand, thus supporting the experimental elucidation. The evaluation of the cell viability on a panel of human tumor cell lines is made. The new Pt(II) complexes exerted cytotoxic effects in a concentration-dependent manner.     

Thermal studies of cobalt(II), nickel(II) and copper(II) 3-substituted-4-salicylideneamino-5-mercapto-1,2,4-triazole complexes

Complexes of Co^II, Ni^II and Cu^II with 3-substituted-4-salicylideneamino-5-mercapto-1,2,4-triazole have been prepared and characterized by elemental analysis, electronic, i.r., e.s.r. and t.g. studies. T.g. studies show that the complexes thermally degrade in two steps. Kinetic and thermodynamic parameters were computed from the thermal decomposition data. The activation energies of both the thermal degradation steps lie in the 0.24–42.67 kJ mol⁻¹ range. This revised version was published online in June 2006 with corrections to the Cover Date.     

Photochemical reactions of group VIB metal carbonyls with heterocyclic Schiff bases derived from 4-amino -3-hydrazino-5-mercapto-1,2,4-triazole

The new complexes, M(CO)₅(Schiff base) [M?=?Cr; 1, Mo; 2, W; 3, Schiff base?=?4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole, SAHMT, a; 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 2HNAHMT, b; 4-(3-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 3HBAHMT, c; 4-(4-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 4HBAHMT, d; 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 5BrSAHMT, e; were synthesized by photochemical reaction of metal carbonyls M(CO)₆ (M?=?Cr, Mo, W) with new heterocyclic Schiff bases derived from 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, a–e. The ligands and complexes have been characterized by elemental analysis, EI-mass spectrometry, FT-IR, ¹H and ¹³C-{¹H}-NMR spectroscopy. The spectroscopic studies show that Schiff bases, a–e, are monodentate and coordinate via azomethine N donor to the central metal atom in M(CO)₅(Schiff base) (M?=?Cr, Mo, W).     

Improved syntheses of 5-substituted-4-amino-3-mercapto-(4H)-1,2,4-triazoles

Two improved methods have been developed for the synthesis of 5-substiluted-4-amino-3-mercapto-(4H)-1,2,4-triazoles. One of these involves the direct hydrazinolysis of potassium 3-aroyldithiocarbazates and the other involves ring-opening and reclosure of 5-substituted-2-mereapto-1,3,4-oxadiazoles to the aminomercaptotriazoles. Both of these methods offer advantages over the classic Hoggarth synthesis.     

Synthesis and biological activity of some novel derivatives of 4-amino-3-(D-galactopentitol-1-yl)-5-mercapto-1,2,4-triazole

To discover new 1,2,4-triazole derivatives which may possess significant biological activities, we synthesized a series of novel 6-aryl-3-(D-galactopentitol-1-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines and 4-(arylmethylidene)amino-5-(D-galactopentitol-1-yl)-3-mercapto-4H-1,2,4-triazoles from 4-amino-3-(D-galactopentitol-1-yl)-5-mercapto-1,2,4-triazole. All the title compounds were characterized by elemental analysis, IR, 1H- and 13C-NMR. Plant growth-regulating activity tests showed that these compounds have remarkable effects on the growth of radish and wheat.     

Synthesis of 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazepines and 4-amino-3-acylvinylthio-1,2,4-triazoles by reaction o acylacetylenes with 4-amino-3-mercapto-1,2,4-triazole

1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazepines have been prepared by treating -acetylenic ketones with 4-amino-3-mercapto-1,2,4-triazole in glacial acetic acid. Terminal acetylenic ketones react with the triazole to form 4-amino-3-acylvinylthio-1,2,4-triazoles. Heating the latter with hydrazine hydrate in alcohol yields substituted pyrazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 990–994, July, 1991.     

3-Methyl-4-amino-5-mercapto-1,2,4-triazole as a ring-colorimetric reagent for the selective microevaluation of Au(III), Ti(I), and Ag(I)

MAMT has been studied for its microanalytical uses. Selective microevaluation of Au(III), Ag(I), and Tl(I) have been carried out with MAMT, incorporating masking and solvent extraction techniques in conjunction with ring colorimetry. MAMT has also been used as a chromogenic reagent for Au(III), while PTC had to be used for Ag(I) and Tl(I) as their MAMT complexes are white.     

Synthesis, spectral characterization, biological and fluorescence studies of lanthanum(III) complexes with 3-substituted-4-amino-5-hydrazino-1,2,4-triazole Schiff bases

Some lanthanum(III) complexes have been synthesized by reacting lanthanum(III) nitrate with Schiff bases derived from 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and substituted salicylaldehydes. All these complexes are soluble in DMF and DMSO and the low molar conductance values observed indicates that they are non-electrolytes. Elemental analyses suggest the complexes have 1:1 stoichiometry of the type La · L · NO₃ · H₂O, and they were characterized further by spectral and thermogravimetric methods. Fluorescence spectra of one of the representative Schiff bases (II) and its lanthanum(III) complex were investigated in various solvents; the complexes were evaluated for their biological activity.     

Complexometric titration of thallium(III), by use of 4-amino-5-mercapto-3-propyl-1,2,4-triazole as replacing reagent

A simple and selective EDTA method using a masking and demasking technique is proposed for the determination of thallium(III). The thallium is complexed with excess of EDTA, the surplus being back-titrated (pH 5-6, hexamine buffer) with zinc sulphate solution (Xylenol Orange as indicator). 4-Amino-5-mercapto-3-propyl-1,2,4-triazole is then added and the mixture heated on a water-bath for 5-10 min to displace EDTA from its thallium complex. The EDTA liberated is titrated with zinc sulphate solution. Reproducible and accurate results are obtained in the range 5-75 mg of thallium with both the relative error and coefficient of variation not exceeding 0.4%.     

Preconcentration of trace metals in natural waters with 2,2′-dipyridyl-4-amino-3-hydrazino-5-mercapto-1,2,4-triazolehydrazone supported on silica gel

The new hydrazone, supported on silica gel, is used to preconcentrate traces of copper, zinc, lead, nickel, cobalt and cadmium from tap, lake and sea water. Conditions for quantitative retention are established. Copper, zinc, lead, cadmium and nickel are quantitatively eluted with 0.1 M EDTA, and cobalt with 2 M perchloric acid. The metals are measured by atomic absorption spectrometry.     

Synthesis of 3-Azido-5-amino-1,2,4-triazole

3-Azido-5-amino-1,2,4-triazole was obtained from 3,5-diamino-1,2,4-triazole in two ways: by partial diazotization-substitution directly in the substrate or at its primarily nitrosation, and also with the use of direct or indirect protection of an amino group with subsequent conversion into azido compound followed by deprotection.     

Reaction of ethyl cyanoacetate with 4-amino-3 mercapto-5R-1,2,4-triazole

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 137–138, January, 1994.     

Sensitive and selective detection of glutathione based on anti-catalytical growth of gold nanoparticles colorimetric sensor

Gold nanoparticles (AuNps) are often employed in different detection paths based on the catalytic growth mechanism; AuNps could act as catalyst for the reduction of AuCl₄^? and result in the enlargement of the original AuNps. However, there are few probes based on the anti-catalytical growth of AuNps in previous studies. In this article, we proposed a simple colorimetric sensor for the detection of glutathione (GSH) based on the anti-catalytical growth of AuNps, the strong affinity of GSH make it readily combine with AuNps or metal ions (AuCl₄^?), and thus inhibit the catalytical growth of AuNps through the specific property of GSH. Therefore, the UV absorbance of detection system could be used to estimate the concentration of GSH, and the probe exhibits highly sensitive and selective detection of the concentration of GSH with a wide linear from 13 to 800 nM within 20 min. Meanwhile, a good linear relationship with correlation coefficient of R² = 0.9795 was obtained. It is believed that this research could broaden the choices of GSH detection methods.     

Sensitive and selective detection of glutathione based on resonance light scattering using sensitive gold nanoparticles as colorimetric probes

In this paper, we reported the development of a highly sensitive and selective resonance light scattering (RLS) technique for glutathione using gold nanoparticle probes. The assay relies upon the distance-dependent optical properties of gold nanoparticles, the self-assembly of glutathione on gold nanoparticles, and the interaction of a 2 : 1 glutathione-Cu(2+) complex. In the presence of Cu(2+), glutathione could rapidly induce the aggregation of gold nanoparticles, thereby resulting in greatly enhanced RLS intensity and red-to-blue (or purple) color change. The concentration of glutathione can be determined by the naked eye or a fluorescence spectrometer. Under the optical conditions, the detection of glutathione can be finished within 20 min, and the detection limit of 10 nM can be reached. The concentration range of the probe is 40-280 nM. The proposed method holds a specific selectivity toward glutathione and it is applied to the detection of glutathione in human serum with satisfactory results. In addition, the assay shows great potential application for disease-associated biomarkers, and it will meet the great demand for amino acid determination in fields such as food processing, biochemistry, pharmaceutical, and clinical analysis.