67-51-6Relevant articles and documents
Tris(3,5-dimethylpyrazole)copper(II) nitrate: As an oxidation catalyst
Sharma, Sagar,Barooah, Nilotpal,Baruah, Jubaraj B.
, p. 171 - 176 (2005)
Tris(3,5-dimethylpyrazole)copper(II) nitrate (A) is a catalyst for mild oxidation of various organic substrates. It acts as catalyst for conversion of benzylamine to benzaldehyde in the presence of hydrogen peroxide. Various benzylic alcohols are converted to corresponding aldehydes and acids by the catalytic amount of the complex (A) with hydrogen peroxide at room temperature. The complex also catalyses dimerisation of 2,6-dimethylphenol and thiophenol. The thermal decomposition of tris(3,5-dimethylpyrazole)copper(II) nitrate at 500°C gives CuO having the monoclinic crystal system. The cyclic voltammogram of the complex tris-(3,5-dimethylpyrazole)copper(II) nitrate shows a quasi-reversible redox cycle at -101 mV (E1/2) versus the Ag/AgCl electrode (+ve scan; scan speed 100 mV/s). The ΔE between anodic and cathodic peaks is 110 mV (ipa/ipc = 1.2).
Selective Synthesis of 3-(α,α-Dibromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one as an Excellent Precursor for the Synthesis of 2-Substituted 4-(4-Hydroxy-6-methyl-2H-2-oxopyran-3-yl)thiazoles as Antimicrobial and Antifungal Agents
Kapoor, Jitander K.,Prakash, Richa,Kumar, Ajay,Saini, Deepika,Arora, Loveena
, p. 899 - 906 (2018)
A selective synthesis of 3-(α,α-dibromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one (3) has been achieved by bromination of DHA using CuBr2/CHCl3-EtOAc. The reaction of 3 with different thioureas/thiomides/thiosemicarbazide offers a convenient and efficient method for the syntheses of 2-substituted 4-(4-hydroxy-6-methyl-2H-2-oxopyran-3-yl)thiazoles. These thiazoles were evaluated for their antimicrobial and antifungal activity.
Pyrazolylamidino ligands from coupling of acetonitrile and pyrazoles: A systematic study
Gmez-Iglesias, Patricia,Arroyo, Marta,Bajo, Sonia,Strohmann, Carsten,Miguel, Daniel,Villafae, Fernando
, p. 12437 - 12448 (2014)
Mixed pyrazole-acetonitrile complexes, both neutral fac-[ReBr(CO)3(NCMe)(pzH)] (pzH = pzH, pyrazole; dmpzH, 3,5-dimethylpyrazole; or indzH, indazole) and cationic fac-[Re(CO)3(NCMe)(pzH)2]A (A = BF4, ClO4, or OTf), are described. Their role as the only starting products to obtain final pyrazolylamidino complexes fac-[ReBr(CO)3(NH=C(Me)pz-κ2N,N)] and fac-[Re(CO)3(pzH)(NH=C(Me)pz-κ2N,N)]A, respectively, is examined. Other products involved in the processes, such as fac-[ReBr(CO)3(pzH)2], fac-[Re(CO)3(NCMe)(NH=C(Me)pz-κ2N,N)]A, and fac-[Re(CO)3(pzH)2(OTf)] are also described. Warming CD3CN solutions of fac-[Re(CO)3(NCMe)(pzH)2]A at 40 °C gives cleanly the pyrazolylamidino complexes [Re(CO)3(pzH)(NH=C(Me)pz-κ2N,N)]A as the only products, pointing to an intramolecular process. This is confirmed by carrying out reactions in the presence of one equivalent of a pyrazole different from that coordinated, which affords complexes where the pyrazolylamidino ligand contains only the pyrazole previously coordinated. When the reactions lead to an equilibrium mixture of the final and starting products, the reverse reaction gives the same equilibrium mixture, which indicates that the coupling reaction of pyrazoles and nitriles to obtain pyrazolylamidino ligands is a reversible intramolecular process. A systematic study of the possible factors which may affect the reaction gives the following results: (a) the yields of the direct reactions are higher for lower temperatures; (b) the tendency of the pyrazoles to give pyrazolylamidino complexes follows the sequence indzH > pzH > dmpzH; and (c) the reaction rates do not depend on the nature of the anion even when a large excess is added. The presence of a small amount of aqueous solution of NaOH catalyzes the reaction. Thus, addition of 0.5-1% of NaOH (aq) to solutions of fac-[ReBr(CO)3(NCMe)(pzH)] (in CD3CN) or fac-[Re(CO)3(NCMe)(pzH)2]A (in CD3CN, CD3NO2 or (CD3)2CO) allowed the syntheses of the corresponding pyrazolylamidino complexes [ReBr(CO)3(NH=C(Me)pz-κ2N,N)] or [Re(CO)3(pzH)(NH=C(Me)pz-κ2N,N)]A with better yields, more rapidly, and in milder conditions.
Halocarbon Encapsulation via Halogen···?€ Interactions in a Bispyrazole-Based Cryptand
Verma, Ashish,Tomar, Kapil,Bharadwaj, Parimal K.
, p. 369 - 375 (2019)
A novel bispyrazole-based expanded cryptand was synthesized via Schiff base condensation reaction having an internal cavity of 160 ?3 with a hydrophobic nature. The cryptand features electron-rich multiple pyrazole rings for enhanced weak noncovalent interactions with the guest molecules. The host-guest capabilities of the cryptand were investigated for encapsulation of the most inactive halogen bond donor molecules (having small σ-hole size), namely, CH2Cl2, CHCl3, CCl4, C2HCl3, C2H4Cl2, and C2H4Br2. Analysis of crystal structures clearly revealed that halogen bonding (C-Cl/Br···π (pyrazole)) and hydrogen bonding (C-H···π(pyrazole)) interactions played a key role in stabilizing the halogenated guests inside the hydrophobic cavity of cryptand. At the same time, the cage is efficiently able to exclude hydrophilic solvent molecules, like, water and methanol, suggesting the hydrophobic nature of the cavity. Due to the comparably large σ-hole in C2H4Br2, it showed the strongest halogen bonding interaction with the host cryptand, while weakest interaction was found for the CH2Cl2 guest which has the smallest size σ-hole. Furthermore, the cryptand is able to adjust its central cavity according to the size of the guest. The biggest cavity size was found for the C2H4Br2 guest, while smallest size was found for the CH2Cl2 guest molecule. This study sheds more light on the interaction of halogenated solvents via halogen and hydrogen bonding, which is critical in understanding and controlling chemical reactions where solvent effects play an important role.
Pd-Catalyzed Asymmetric Dearomatization of Indoles via Decarbonylative Heck-Type Reaction of Thioesters
Han, Ming-Liang,Huang, Wei,Liu, Yu-Wen,Liu, Min,Xu, Hui,Xiong, Hai,Dai, Hui-Xiong
, p. 172 - 177 (2021)
We report herein a palladium-catalyzed ligand-promoted asymmetric dearomatization of indoles via the decarbonylation of thioesters and the subsequent reductive Heck reaction. This protocol provides a facile and efficient way to construct an aza-quaternary stereocenter at the C2 position of indolines. A variety of functional groups and substitutions could be well tolerated, affording the substituted indolines with high enantioselectivities.
Synthesis and Cyclizations of N-(Thieno[2,3-b]pyridin-3-yl)cyanoacetamides
Chigorina,Bespalov,Dotsenko
, p. 2018 - 2026 (2019)
3-Aminothieno[2,3-b]pyridine-2-carboxylic acid esters readily reacted with 3,5-dimethyl-1-(cyanoacetyl)-1H-pyrazole to give previously unknown N-(thieno[2,3-b]pyridin-3-yl)cyanoacetamides. Reactions of the latter with 2-(arylmethylidene)malononitriles were nonselective, and mixtures of different heterocyclization products were generally formed. The cyclization of ethyl 4,6-dimethyl-3-[(cyanoacetyl)amino]thieno[2,3-b]-pyridine-2-carboxylate afforded 2,4-dihydroxy-7,9-dimethylthieno[2,3-b : 4,5-b′]dipyridine-3-carbonitrile whose tautomeric equilibrium was studied by DFT quantum chemical calculations. In silico analysis of biological activity of the synthesized compounds was performed.
Nickel (II) and cobalt (II) complexes with bidentate nitrogen-sulfur donor pyrazole derivative ligands: Syntheses, characterization, X-ray structure, electrochemical studies, and antibacterial activity
Soltani, Behzad,Ghorbanpour, Monireh,Ziegler, Christopher J.,Ebadi-Nahari, Mostafa,Mohammad-Rezaei, Rahim
, (2020)
The synthesis, characterization, antibacterial activity and cyclic voltammetry of bidentate N,S donor pyrazole derivative ligands abbreviated as Na(EtNCSPz) (1), Na(PhNCSPz) (2), Na(PhNCSPzme2) (3), Na(PhNCSPzme3) (4) and their metal complexes with Ni(II) and Co(II) metal ions are reported, where Pz = pyrazole, Pzme2 = 3,5-dimethylpyrazole and Pzme3 = 3,4,5-trimethylpyrazole. All of the synthesized ligands and complexes have been characterized by physicochemical and spectroscopic methods and the crystal structures of [Ni(EtNCSPz)2] (1a) and [Ni(PhNCSPzMe3)2] (4a) have been determined by X-ray diffraction analysis. The X-ray crystal structure of both the complexes describe a square planar coordination geometry. The electrochemical studies show that the synthesized complex is an electrochemically active species, furthermore, substitution electron donating groups on the ligands shift the reduction and oxidation potentials to negative values. Antibacterial activity results indicate these complexes possess high activity against gram-positive and gram-negative bacteria compare to the free ligands.
Predicting the catalytic activity of azolium-based halogen bond donors: an experimentally-verified theoretical study
Bolotin, Dmitrii S.,Il'in, Mikhail V.,Novikov, Alexander S.,Suslonov, Vitalii V.,Sysoeva, Alexandra A.
, p. 7611 - 7620 (2021/09/22)
This report demonstrates the successful application of electrostatic surface potential distribution analysis for evaluating the relative catalytic activity of a series of azolium-based halogen bond donors. A strong correlation (R2> 0.97) was observed between the positive electrostatic potential of the σ-hole on the halogen atom and the Gibbs free energy of activation of the model reactions (i.e., halogen abstraction and carbonyl activation). The predictive ability of the applied approach was confirmed experimentally. It was also determined that the catalytic activity of azolium-based halogen bond donors was generally governed by the structure of the azolium cycle, whereas the substituents on the heterocycle had a limited impact on the activity. Ultimately, this study highlighted four of the most promising azolium halogen bond donors, which are expected to exhibit high catalytic activity.
High Proton Conductivity of a Cadmium Metal-Organic Framework Constructed from Pyrazolecarboxylate and Its Hybrid Membrane
Wang, Feng-Dong,Su, Wen-Hui,Zhang, Chen-Xi,Wang, Qing-Lun
supporting information, p. 16337 - 16345 (2021/11/01)
A new type of metal-organic framework, [Cd2(pdc)(H2O)(DMA)2]n (pdc = 3,5-pyrazoledicarboxylic acid; DMA = dimethylamine), named Cd-MOF, was synthesized and characterized. There are regular rectangular pore channels containing a large number of dimethylamine cations in the crystal structure. AC impedance test results show the proton conductivity of Cd-MOF reaches 1.15 × 10-3 S cm-1 at 363 K and 98% RH. In order for its application in fuel cells, the Cd-MOF was introduced into a sulfonated polyphenylene oxide matrix to prepare a hybrid membrane, and the proton conductivity of the hybrid membrane has a high value of 2.64 × 10-1 S cm-1 at 343 K and 98% RH, which is higher than those of most MOF polymer hybrid membranes. The proton conductivity of the hybrid membrane of the SPPO polymer still maintains a certain degree of stability in a wide temperature range. To the best of our knowledge, it is the first proton exchange membrane that combines pyrazolecarboxylate cadmium MOFs and an SPPO polymer with high proton conductivity and good stability. This research may help to further develop the application of MOFs in the field of proton exchange membrane fuel cells.
Copper (II) complexes with novel Schiff-based ligands: synthesis, crystal structure, thermal (TGA–DSC/FT-IR), spectroscopic (FT-IR, UV-Vis) and theoretical studies
Campos, Guilherme Fava,Martins, Gabriel Rodrigues,Moreira, Jeniffer Meyer,Schwalm, Cristiane Storck,Tirloni, Bárbara,de Campos Pinto, Leandro Moreira,de Carvalho, Cláudio Teodoro
, (2021/05/10)
This study aimed to synthesize two novel Schiff-base ligands through the condensation between N-(2-aminoethyl)pyrazoles and 2-hydroxy-1-naphthaldehyde, which are: NaphPz ((E)-1-(((2-(1H-pyrazol-1-yl)ethyl)imino)methyl)naphthalen-2-ol)) and NaphDPz ((E)-1-(((2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl)imino)methyl)naphthalen-2-ol). These novel pyrazole-imines were synthesized, characterized and used as copper (II) ion complexing agents. Different synthetic routes have been adapted to obtain the [Cu(NaphPz)Cl], [Cu(NaphDPz)Cl] and [Cu(NaphPz)2] complexes in the solid state, the first two in the crystalline form and the latter as a powder. The minimum metal–ligand stoichiometry for the three complexes was defined by TGA–DSC thermoanalytical data and by single-crystal X-ray diffraction for the crystalline samples which belong to the P21/n space group. The products of the thermal decomposition of the material were also monitored by TGA–DSC/FT-IR in air and N2 atmospheres in order to suggest how thermal decomposition of the organic portion of the complex occurs. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations compared to experimental results (UV-Vis and FT-IR) show a high degree of correlation. From HOMO/LUMO orbitals, the main major charge distributions, responsible for the absorption bands of the complexes, were determined.
