0000000000496178
AUTHOR
Mimoun Chadlaoui
[(Pyridylcarbonyl)pyridyl]triazolopyridines, Useful Ligands for the Construction of Polynuclear Coordination Compounds – Synthesis, Crystal Structure and Magnetic Properties of a Novel Tetranuclear Copper(II) Cubane
A new tetranuclear cubane Cu4O4 complex has been synthesised from assembly of CuII ions and the polydentate ligand (pyridin-2-yl){6-([1,2,3]triazolo[1,5-a]pyridin-3-yl)pyridin-2-yl}methanone. Crystallographic analysis indicates that the Cu4O4 unit has an S4 symmetry. The magnetic properties have been analysed using the H = –2Σi,jJijSiSj spin Hamiltonian. Two distinct coupling constants, 2J1,3 = –37.4 cm–1 and 2J1,2 = –2.6 cm–1, obtained from the fitting of the experimental data have been rationalised on the basis of a density functional study of magnetostructural correlations in cubane complexes containing the Cu4O4 core. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
ESR and electrochemical studies of 2-acylpyridines and 6,6'-diacyl-2,2'-bipyridines.
Abstract The ESR spectra of radicals obtained by electrolytic reduction of 2-acylpyridines and 6,6′-diacyl-2,2′-bipyridines were measured in dimethylsulfoxide (DMSO) and analyzed by quantum chemical calculations. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO solvent. The results showed a two step reduction mechanism, first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete a…
ESR, electrochemical and cyclodextrin-inclusion studies of triazolopyridyl pyridyl ketones and dipyridyl ketones derivatives.
Abstract The electron spin resonance (ESR) spectra of free radicals obtained by electrolytic reduction of triazolopyridyl pyridyl ketones and dipyridyl ketones derivatives were measured in dimethylsulfoxide (DMSO). The hyperfine patterns indicate that the spin density delocalization is dependent of the rings presented in the molecule. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO as solvent. When one carbonyl is present in the molecule one step in the reduction mechanism was observed while two carbonyl are present two steps were detected. The first wave was assigned to the generation of the correspondent free radical species, and the second wave…
Co(II) chemistry of 2,6-bis(2-pyridylcarbonyl)pyridine: an icosanuclear Co cluster exhibiting superparamagnetic relaxation.
High-nuclearity transition-metal complexes (clusters) are of special interest in chemistry and physics because, both in terms of size and physical properties, they bridge the gap between the microscopic and macroscopic world, and between quantum and classical systems. In terms of size, the smallest classical nanoparticles fabricated today are the same size as the largest metal clusters that are synthesized by bottom-up methods. In terms of physical properties, certain transition-metal clusters exhibit single-molecule magnetism at low temperatures, that is, they retain their magnetization in zero field in a manner analogous to that of classical macroscopic magnets, but at the same time they …
Synthesis of novel polypyridylcarbonylpyridines from triazolopyridines. Building blocks in supramolecular chemistry
The synthesis from triazolopyridines 1, of novel triazolopyridylcarbonylpyridylcarbonyltriazolopyridines (TPyCOPyCOTPy) (tpcpctp) 7, and polypyridylcarbonylpyridines (pPyCOPy) (ppcp) 14, building blocks in supramolecular chemistry, is described. These compounds are interesting polynitrogenated ligands as potential molecular sensors, new magnetic materials, single molecular magnets, or in the emerging science of nanomaterials. Abarca Gonzalez, Belen, Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es
Triazolopyridines 22.1 Description of new 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d]pyrimidines
The new heteroaromatic compounds, 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d] pyrimidines 11a-c, were synthesized in two steps from readily available triazolopyridines 1a-c. Regioselective lithiation of 1a-c followed by treatment with 2-cyanopyridine gave a mixture of compounds 5a-c, and 11a-c in moderate to low yields, together with gums. Similar reactions with the triazolopyridine 1d gave as the only identified compound the triazolopyridine derivative 5d. Abarca Gonzalez, Belen, Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es
X-Ray characterization of 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-d]pyrimidine
Abarca Gonzalez, Belen. Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es ; Ramirez de Arellano Sanchez, Maria del Carmen, Ramirezdearellano@uv.es
Properties of a triazolopyridine system as a molecular chemosensor for metal ions, anions, and amino acids.
The characteristics as a chemosensor of the compound 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-]pyrimidine (1) have been analyzed. Interaction with Cu(2+) produces a quenching of the fluorescence, while interaction with Zn(2+) leads to a quenching of the fluorescence followed by a bathochromic shift. The crystal structure of the Zn(1)(H(2)O)(3)(ClO(4))(2) x H(2)O complex shows the coordination of Zn(2+) through the terpyridine moiety. The octahedral site is completed by three water molecules. Interactions of the Zn(2+) complex with the anions sulfate, nitrate, nitrite, and dihydrogenphosphate in ethanol produce hypsochromic shifts and restoration of the fluorescence wh…
3-(2-Pyridyl)-[1,2,3]triazolo[1,5-a]pyridines. An experimental and theoretical (DFT) study of the ring-chain isomerization
An experimental (1H NMR) and theoretical (DFT) study of the ring-chain-ring isomerization of 3-(2-pyridyl)-[1,2,3]triazolo[1,5-a]pyrid-7-yl derivatives (A) into 6-{[1,2,3]triazolo[1,5-a]pyrid-3-yl}-2-pyridyl derivatives (B) has been carried out. Based on the calculations, a mechanism of several steps will be proposed. The experimental results as well as the calculations lead to the conclusion that the A-B ratio depends on the electronic properties of the substituents. © The Royal Society of Chemistry 2005.
An "S"-shaped pentanuclear CuII cluster derived from the metal-assisted hydrolysis of pyCOpyCOpy: structural, magnetic and spectroscopic studies.
Reaction of [Cu2(O2CMe)4(H2O)2] with 2,6-di-(2-pyridylcarbonyl)-pyridine (pyCOpyCOpy or dpcp) in MeCN–H2O 10 : 1, led to the pentanuclear copper(II) complex [Cu5(O2CMe)6{pyC(O)(OH)pyC(O)(OH)py}2] (1) which crystallizes in the triclinic P space group. The copper(II) atoms are arranged in an “S”-shaped configuration, and are bridged by the doubly deprotonated bis(gem-diol) form of the ligand, pyC(O)(OH)pyC(O)(OH)py2−. Magnetic susceptibility data indicate the interplay of both ferro- and antiferromagnetic intramolecular interactions stabilizing an S = 3/2 ground state. Fitting of the data according to a next-nearest-neighbour model {Ĥ = −[J1(Ŝ1Ŝ2 + Ŝ1′Ŝ2′) + J2(Ŝ2Ŝ3 + Ŝ3′Ŝ2′) + J3(Ŝ1Ŝ3 + Ŝ3′Ŝ…
Triazolopyridines 22.1 Description of new 7,9-di(2-pyridyl)[1,2,3]triazolo[5',1':6,1]pyrido[3,2-d]pyrimidines
The new heteroaromatic compounds, 7,9-di(2-pyridyl)(1,2,3)triazolo(5',1':6,1)pyrido(3,2-d) pyrimidines 11a-c, were synthesized in two steps from readily available triazolopyridines 1a-c. Regioselective lithiation of 1a-c followed by treatment with 2-cyanopyridine gave a mixture of compounds 5a-c, and 11a-c in moderate to low yields, together with gums. Similar reactions with the triazolopyridine 1d gave as the only identified compound the triazolopyridine derivative 5d.
The chemistry of [1,2,3]triazolo[1,5- c ]pyrimidine
Abstract Reactions of [1,2,3]triazolo[1,5-c]pyrimidine 2 with some electrophiles and nucleophiles are reported. Triazole ring opening and loss of nitrogen is the principal reaction with electrophiles. With strong acids protonation on N6 competes successfully. Derivatives in which the pyrimidine ring has been opened are obtained in reactions with nucleophiles. No stable simple substitution compounds were found.
Triazolopyridines. Part 24: New polynitrogenated potential helicating ligands
The synthesis of novel 7-{[1,2,3]triazolo[1,5-a]pyridin-3-yl}-[1,2,3]triazolo[1,5-a]pyridines 7, 2-pyridyl-[1,2,3]triazolo[1,5-a]pyrid-7-ylmethanols 11, 3-(6-substituted-2-pyridyl)-[1,2,3]triazolo[1,5-a]pyridines 12, and 7,7′-disubstituted-3,3′-[1,2,3]triazolo[1,5-a]pyridine 20, interesting polynitrogenated ligands as potential helicating compounds or luminescent sensors, from [1,2,3]triazolo[1,5-a]pyridines is described.
X-Ray characterization of 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5′,1′:6,1]pyrido[2,3-d]pyrimidine
The structure of a new compound 3-methyl-6,8-di(2-pyridyl)[1,2,3]triazolo[5′,1′:6,1]pyrido[2,3- d]pyrimidine 3, formed in the reaction of 3-methyl-[1,2,3]triazolo[1,5-a]pyridine with 2-cyanopyridine, is determined by X-ray diffraction analysis. Abarca Gonzalez, Belen. Belen.Abarca@uv.es ; Ballesteros Campos, Rafael, Rafael.Ballesteros@uv.es ; Chadlaoui, Mimoun, michad@alumni.uv.es ; Ramirez de Arellano Sanchez, Maria del Carmen, Ramirezdearellano@uv.es