Triazole Rings (triazole + ring)

Distribution by Scientific Domains

Selected Abstracts

Acid,base behavior of triazoleporphyrazines in proton-donating media

O. G. Khelevina
Abstract The acid,base properties of some peripheral substituted triazoleporphyrazines in proton-donating media with poor-donating character were experimentally studied. The substitution of one pyrrole moiety in the porphyrazine-like compounds by one triazole ring in the triazoleporphyrazines leads to an increase in the basicity. The protonation of the triazoleporphyrazines results in a hypsochromic shift of the Q-bands in the UV,visible spectra. A DFT study of some selected structural models of the unsubstituted triazoleporphyrazine shows that the protonation strongly influences on the molecular electron structure of this compound and that it occurs preferentially through the nitrogen atom located at position 4 of triazole ring. The protonation through the other basic centers (the triazoleporphyrazine is a multicenter conjugated base) leads to different protonated forms which differ notably in their aromatic character. Therefore, this compound could be considered an intramolecular switch of aromaticity. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Synthesis, characterization and studies of new 3-benzyl-4H -1,2,4-triazole-5-thiol and thiazolo[3,2- b][1,2,4]triazole-5(6H)-one heterocycles

Abdelwareth A. O. Sarhan
3-Benzyl-4-phenyl-1,2,4-triazole-5-thiol (1) was synthesized and used as starting material for preparation of 1,2,4-triazole bearing substituted thiosemicarbazides moiety (4a-d) in high yields. The thiosemicarbazides 4a-d were cyclized in basic medium to give two triazole rings linked by thiomethylene group (5a-d), while cyclization of thiosemicarbazides 4a-d with chloroacetyl chloride in the presence of CHCl3 and K2CO3 afforded the thiazolidinone derivatives 6a-d. The reaction of thiosemicarbazides 4a-c with phenacyl bromide in the presence of EtOH and fused CH3COONa gave the corresponding thiazoline ring systems 7a-c. Condensation of the 3-benzyl-1,2,4-triazole-5(1H)-thiol (1) with chloroacetic acid and aromatic aldehydes (8a- g) in boiling acetic acid/acetic anhydride mixture in the presence of fused sodium acetate gave one single isomer only, which might be 9a-g or 10a-g. Upon application of Micheal addition reaction on compounds 9a-e with cyclic secondary amines such as piperidine or morpholine the 2-benzyl-6-(,-amino-aryl/methyl)-1,3-thiazolo[3,2- b][1,2,4]-triazol-5-ols (11a-j) were obtained in good yields The structure of all new compounds were determined using both spectral and elemental analyses. [source]

catena -Poly[[[tetraaquazinc(II)]-,-4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole] sulfate monohydrate] and poly[[bis(,-4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole)diaquacopper(II)] dinitrate octahydrate]

Hai-Ying Wang
The isomeric bent triazole-containing ligands 4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole (L1) and 4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole (L2) have been used to create the two novel title complexes catena -poly[[[tetraaquazinc(II)]-,-4-amino-3,5-di-3-pyridyl-4H -1,2,4-triazole] sulfate monohydrate], {[Zn(C12H10N6)(H2O)4]SO4·H2O}n, (I), and poly[[diaquabis(,-4-amino-3,5-di-4-pyridyl-4H -1,2,4-triazole)copper(II)] dinitrate octahydrate], {[Cu(C12H10N6)2(H2O)2](NO3)2·8H2O}n, (II). The ZnII and CuII atoms are all six-coordinated in approximately octahedral environments. Compound (I) presents a sinusoidal chain generated by ZnO4 cores which are bridged by L1 ligands in a cisoid conformation. These sinusoidal chains are bound to each other by O,H...O hydrogen bonds between coordinated water molecules of neighboring chains into a two-dimensional network. These layers stack in an ,ABAB, sequence and are further linked into a three-dimensional framework through O,H...N hydrogen bonds between coordinated water molecules and the N atoms of the triazole rings. In (II), the CuII centers are bridged by the L2 ligands to form a two-dimensional network with square grids. All of the two-dimensional nets also stack alternately along the crystallographic a axis. Neighboring layers are further linked into a three-dimensional framework via interlayer N,H...N hydrogen bonds between ,NH2 groups of the triazole rings and the N atoms in the triazole rings. [source]

A novel dimeric zinc(II) complex: bis­[,-1,2-bis­(1H -1,2,4-triazol-1-yl)­ethane-,2N4:N4,]­bis­[diisothio­cyanato­zinc(II)]

Yu-Mei Zhang
The coordination geometry of the ZnII atom in the title complex, [Zn2(NCS)4(C6H8N6)2], is that of a distorted tetra­hedron, in which the ZnII atom is coordinated by four N atoms from the triazole rings of two symmetry-related 1,2-bis­(1,2,4-triazol-1-yl)ethane ligands and two thio­cyanate ligands. Two ZnII atoms are bridged by two organic ligands to form a dimer. The dimer lies about an inversion center. [source]

N -Cyclo­hexyl-2-[5-(4-pyridyl)-4-(p -tolyl)-4H -1,2,4-triazol-3-yl­sulfanyl]­acetamide dihydrate

Muharrem Dinçer
In the title compound, C22H25N5OS·2H2O, the mol­ecules are stacked in columns running along the b axis. In this arrangemant, the mol­ecules are linked to each other by a combination of one two-centre N,H,O hydrogen bond and four two-centre O,H,O hydrogen bonds containing two types of ring motif, viz.R44(10) and R33(11). In the crystal structure, centrosymmetric ,,, inter­actions between the triazole rings, with a distance of 3.691,(2),Å between the ring centroids, also affect the packing of the mol­ecules. [source]

Protein,Inorganic Array Construction: Design and Synthesis of the Building Blocks

Abstract Herein we describe the design and synthesis of the first series of di-functional ligands for the directed construction of inorganic-protein frameworks. The synthesized ligands are composed of a metal-ion binding moiety (terpyridine-based) conjugated to an epoxysuccinyl peptide, known to covalently bind active cysteine proteases through the active-site cysteine. We explore and optimize two different conjugation chemistries between the di-functionalized metal-ion ligand and the epoxysuccinyl-containing peptide moiety: peptide-bond formation (with limited success) and CuI -catalysed click chemistry (with good results). Further, the complexation of the synthesized ligands with FeII and NiII ions is investigated: the di-functional ligands are confirmed to behave similarly to the parent terpyridine. As designed, the peptidic moiety does not interfere with the complexation reaction, in spite of the presence of two triazole rings that result from the click reaction. ES-MS together with NMR and UV/Vis studies establish the structure, the stoichiometry of the complexation reactions, as well as the conditions under which chemically sensitive peptide-containing polypyridine ligands can undergo the self-assembly process. These results establish the versatility of our approach and open the way to the synthesis of di-functional ligands containing more elaborated polypyridine ligands as well as affinity labels for different enzyme families. As such, this paper is the first step towards the construction of robust supramolecular species that cover a size-regime and organization level previously unexplored. Im Folgenden beschreiben wir das gezielte Design und die Synthese di-funktionaler Liganden zum erstmaligen Aufbau supramolekularer Metall-Protein-Hybridarchitekturen. Die synthetisierten Liganden enthalten eine Metallionen-Bindungsstelle (auf Terpyridin-Basis), die mit einem Epoxysuccinyl-Peptid konjugiert wurde. Diese Peptide binden bekannterweise an die aktiven Cysteine im katalytischen Zentrum von Cystein-Proteasen. Wir untersuchen und optimieren zwei verschiedene Arten chemischer Konjugations-Systeme zwischen den di-funktionalen Metallionen-Liganden und dem Epoxysuccinyl-enthaltenden Peptidrest: Bildung einer Peptid-Bindung (mit geringem Erfolg) und CuI -katalysierte click Chemie (mit signifikantem Erfolg). Wie beabsichtigt, erfolgt die Komplexierung von FeII - und NiII -Ionen an den synthetisierten Liganden hochselektiv am Terpyridylrest und nicht an den Triazol-Ringen des Peptidrests, die aus der click Reaktion resultieren. Struktur, Stöchiometrie der Komplexbildung und Bedingungen für den Selbstorganisationsprozess der empfindlichen poly-Pyridyl-Peptid-Liganden wurden durch ESI-MS-, NMR- und UV-VIS-Untersuchungen dokumentiert. Diese Ergebnisse demonstrieren die Vielseitigkeit unseres neuartigen Ansatzes zur Synthese maßgeschneiderter di-funktionaler Liganden mit poly-Pyridyl-Resten und Affinity Label für unterschiedliche Enzymfamilien. Die Arbeit repräsentiert somit den ersten Schritt in der Entwicklung einer stabilen, supramolekularen Architektur in bisher unerreichter Größenordnung und Organisationsgrad. [source]

Modular Synthesis and Dynamics of a Variety of Donor,Acceptor Interlocked Compounds Prepared by Click Chemistry


Abstract A series of donor,acceptor [2]-, [3]-, and [4]rotaxanes and self-complexes ([1]rotaxanes) have been synthesized by a threading-followed-by-stoppering approach, in which the precursor pseudorotaxanes are fixed by using CuI -catalyzed Huisgen 1,3-dipolar cycloaddition to attach the required stoppers. This alternative approach to forming rotaxanes of the donor,acceptor type, in which the donor is a 1,5-dioxynaphthalene unit and the acceptor is the tetracationic cyclophane cyclobis(paraquat- p -phenylene), proceeds with enhanced yields relative to the tried and tested synthetic strategies, which involve the clipping of the cyclophane around a preformed dumbbell containing ,-electron-donating recognition sites. The new synthetic approach is amenable to application to highly convergent sequences. To extend the scope of this reaction, we constructed [2]rotaxanes in which one of the phenylene rings of the tetracationic cyclophane is perfluorinated, a feature which significantly weakens its association with ,-electron-rich guests. The activation barrier for the shuttling of the cyclophane over a spacer containing two triazole rings was determined to be (15.5±0.1),kcal,mol,1 for a degenerate two-station [2]rotaxane, a value similar to that previously measured for analogous degenerate compounds containing aromatic or ethylene glycol spacers. The triazole rings do not seem to perturb the shuttling process significantly; this property bodes well for their future incorporation into bistable molecular switches. [source]