1137-68-4Relevant articles and documents
Dehydrogenative synthesis of benzimidazoles under mild conditions with supported iridium catalysts
Tateyama, Keisuke,Wada, Kenji,Miura, Hiroki,Hosokawa, Saburo,Abe, Ryu,Inoue, Masashi
, p. 1677 - 1684 (2016)
Solid supported iridium catalysts, which show excellent activity for the dehydrogenative synthesis of benzimidazoles from primary alcohols and phenylenediamine derivatives under mild reaction conditions, were developed. Among the catalysts examined, the titania-supported iridium catalyst showed the highest activity, and benzimidazole derivatives were selectively produced at temperatures of 80°C or higher. For example, the reaction of phenylenediamine (1a) with benzyl alcohol (2a) in the presence of Ir(1.0 wt%)/TiO2 (1.0 mol%, towards 1a) at 120°C selectively gave 2-phenylbenzimidazole (3aa) in 80% yield after 6 h and over 90% yield after 18 h. A high turnover number (TON) of more than 800 was achieved in the reaction at a higher substrate-to-catalyst ratio. Reduction of the catalysts under a hydrogen atmosphere at around 500 to 600°C is essential for their significant activity. Characterization of the catalysts by gas adsorption, XRD, XPS, H2-TPR, TEM, and XAFS techniques revealed that highly-dispersed nanoparticles of the iridium(0) species (ca. 1 to 2 nm in diameter) formed on TiO2 are responsible for the catalysis. The catalysts could be recycled without a significant loss of activity, and the leaching of the iridium species into the solution during the catalytic runs was negligible, which suggests that the present catalysts would be excellent from both environmental and practical perspectives.
An efficient and one-pot synthesis of imidazolines and benzimidazoles via anaerobic oxidation of carbon-nitrogen bonds in water
Gogoi, Pranjal,Konwar, Dilip
, p. 79 - 82 (2006)
The system, I2/KI/K2CO3/H2O, oxidizes carbon-nitrogen bonds for the synthesis of imidazolines and benzimidazoles from aldehydes and diamines under anaerobic conditions in water at 90°C with excellent yields. The process is green, mild and inexpensive.
Efficient and high colour-purity green-light polymer light-emitting diodes (PLEDs) based on a PVK-supported Tb3+-containing metallopolymer
Liu, Lin,Pang, Mengyuan,Chen, Hongting,Fu, Guorui,Li, Baoning,Lü, Xingqiang,Wang, Lei
, p. 9021 - 9027 (2017)
Based on the free-radical copolymerization of the green-light complex monomer [Tb(eb-PMP)3(4-VB-PBI)] (2; Heb-PMP = 4-(2-ethylbutanoyl)-1-phenyl-3-methyl-1H-pyrazol-5(4H)-one; 4-VB-PBI = 1-(4-vinylbenzyl)-(pyridin-2-yl)-1H-benzo[d]imidazole) with NVK (N-vinylcarbazole), the obtained Tb3+-containing metallopolymer poly(NVK-co-2) with an energy transfer from additional PVK to Tb3+ ion was used as the emitting material of polymer light-emitting diodes (PLEDs); it exhibited record renewed efficiencies (24.63 cd A-1, 7.81%, and 6.45 lm W-1) of Tb3+-based extreme colour-purity green-light PLEDs and superior performance of colour-stability and low efficiency roll-off to small-molecule Tb3+-complex's OLEDs.
Semi-empirical computation on mechanism of imidazolines and benzimidazoles synthesis and their QSAR studies
Hazarika, Swapnali,Konwar, Dilip,Bora, Manas Jyoti
, p. 5073 - 5078 (2014)
A green, mild and anaerobic synthesis of imidazolines and benzimidazoles from aldehydes and diamines using I2/KI/K2CO3/H2O system has been investigated by semi-empirical methods. The observed efficient direction of the above synthesis has been modeled from a comparison of the energies of four possible transition states arising from mono and di additions of iodines in the configured molecules. In the reaction I1 B is the most favorable transition state [TS] which is shown to be 20 Kcal/mol by PM3 analyses. The resulting trends of relative transition states energies are in excellent agreement with the experimental observations. Also, the bond order, bond length, heat of formation is in good agreement to the formation of product B. In order to establish the suitable mechanism of the reaction a quantitative structure activity relationship analysis has been made using hydrophobicity as the molecular descriptor. In this analysis the values of refractivity, polarizability, hydration energy, electron affinity, ionization potential and dipole moment of the compounds have been correlated with their hydrophobicity which has been taken as the molecular property.
Mild and highly efficient protocol for the synthesis of benzimidazoles using samarium triflate [Sm(OTf)3]
Narsaiah, A. Venkat,Reddy, A. Ramesh,Yadav
, p. 262 - 267 (2011)
One-pot synthesis of benzimidazole compounds from ortho-phenylenediamine and a variety of aldehydes was developed under mild reaction conditions. All the reactions were carried out in the presence of samarium triflate (10mol%) in acetonitrile at room temperature. Copyright Taylor & Francis Group, LLC.
Anticancer copper pyridine benzimidazole complexes: ROS generation, biomolecule interactions, and cytotoxicity
Prosser, Kathleen E.,Chang, Stephanie W.,Saraci, Felix,Le, Phuc H.,Walsby, Charles J.
, p. 89 - 99 (2017)
The Cu(II) complex CuCl2(pbzH), pbzH = 2-(2-pyridyl)benzimidazole, and derivatives modified at the non-coordinated nitrogen of the benzimidazole fragment, have been studied as anticancer agents. These compounds show promising cytotoxicity against A549 adenocarcinomic alveolar basal epithelial cells with IC50 values in the range of 5–10 μM. Importantly, this activity is higher than either CuCl2·2H2O or the individual ligands, demonstrating that ligand coordination to the Cu(II) centres of the complexes is required for full activity. Electron paramagnetic resonance (EPR) and UV–Vis spectroscopies were used to characterize the solution behaviour of the complexes. These studies demonstrate: (i) two types of solvated species in buffer, (ii) both coordinate and non-coordinate interactions with albumin, and (iii) weak interactions with DNA. Further DNA studies using agarose gel electrophoresis demonstrate strand cleavage by the complexes in the presence of ascorbate, which is mediated by reactive oxygen species (ROS). Through a fluorescence-based in vitro assay, intracellular ROS generation in the A549 cell line was observed; indicating that damage by ROS is responsible for the observed activity of the complexes.
Ti, Zr and v complexes with N-allyl functionalized heterocyclic ligands as catalysts for ethylene polymerization Dedicated to Professor Max Herberhold on the occasion of his 80th birthday (August 02, 2016).
Elagab, Hamdi Ali,Alt, Helmut G.
, p. 17 - 29 (2016)
Titanium, zirconium and vanadium complexes with N-allyl functionalized 1,2-bis(benzimidazolyl)benzene, 1,2-bis(benzimidazolyl)ethane, 1,1-bis(benzimidazolyl)methane, 2,2-bis(benzimidazolyl), 2,6-bis(benzimidazolyl)pyridine and 2-(benzimidazolyl)pyridine ligands were synthesized and characterized. After activation with methylaluminoxane (MAO) they were applied for catalytic ethylene polymerization. The performance of such homogeneous catalysts is unique: they have high activities (up to 3278 kg PE/mol cat h), they produce bimodal or multimodal resins with high molecular weights and they have the potential to produce their own support for heterogeneous polymerization reactions. Such catalysts combine all features for single-reactor bimodal polyethylene technology.
Iron sulfide catalyzed redox/condensation cascade reaction between 2-amino/hydroxy nitrobenzenes and activated methyl groups: A straightforward atom economical approach to 2-hetaryl-benzimidazoles and -benzoxazoles
Nguyen, Thanh Binh,Ermolenko, Ludmila,Al-Mourabit, Ali
, p. 118 - 121 (2013)
Iron sulfide generated in situ from elemental sulfur and iron was found to be highly efficient in catalyzing a redox/condensation cascade reaction between 2-amino/hydroxy nitrobenzenes and activated methyl groups. This method represents a straightforward and highly atom economical approach to 2-hetaryl-benzimidazoles and -benzoxazoles.
Two new mixed copper(ii)-dipeptide complexes of N, N -donor heterocycle ligands: Studies on their non-covalent DNA binding, chemical nuclease, antioxidant and anticancer activities
Gan, Qian,Zhang, Chun-Lian,Wang, Bing-Feng,Xiong, Ya-Hong,Fu, Yin-Lian,Mao, Zong-Wan,Le, Xue-Yi
, p. 35952 - 35965 (2016)
Two novel mononuclear mixed ligand copper(ii) complexes, [Cu(Gly-l-val)(HPB)(H2O)]·ClO4·1.5H2O (1) and [Cu(Gly-l-val)(PBT)(H2O)]·ClO4 (2) (Gly-l-val = glycyl-l-valine, HPB = 2-(2′-pyridyl)benzimidazole, PBT = 2-(2′-pyridyl)benzothiazole), have been synthesized and characterized using various analytical and spectroscopic methods. The interactions of the complexes with DNA have been explored by viscometry, thermal denaturation, cyclic voltammetry (CV), agarose gel electrophoresis and spectroscopic means (UV absorption, circular dichroism (CD) and fluorimetry), as well as molecular docking techniques. These studies confirmed the mode of the complexes bound to calf thymus DNA (CT-DNA) through insertion with certain affinity (Kb = 3.211 × 105 M-1 for 1 and 4.734 × 104 M-1 for 2). In the fluorimetric experiments of thermodynamics (KSV = 1.145 × 104 M-1 for 1 and 2.634 × 103 M-1 for 2), the changes in enthalpy (ΔH > 0), entropy (ΔS > 0) and Gibbs free energy (ΔG ?OH as a reactive oxygen species. Furthermore, the molecular docking technique was applied to ascertain the mode of action for the complexes towards DNA. Moreover, superoxide dismutase (SOD) activity studies were performed using the photoreduction of nitroblue tetrazolium (NBT) under a non-enzymatic system and the antioxidant activities of 1 and 2 determined with IC50 values of 0.337 and 0.146 μM, respectively. The cytotoxicity of the Cu(ii) complexes against A549, HeLa, PC-3 tumor cell lines and NIH3T3 (non-tumor cell line) was studied by an MTT assay and it was found that 1 exhibited better cytotoxicity against A549 and PC-3 than 2 and the widely used drug cisplatin.
A comparative study of the optical and electroluminescent properties of EuIII complexes with TTA and 2-(2′-pyridyl)azoles: The crystal structure of [Eu(TTA)3(PBO)]
Gao, Li-Hua,Guan, Min,Wang, Ke-Zhi,Jin, Lin-Pei,Huang, Chun-Hui
, p. 3731 - 3737 (2006)
Two EuIII mixed-ligand complexes, namely [Eu(TTA) 3(PBO)] and [Eu(TTA)3(PBT)] [TTA = 1,1,1-trifluoro-3-(2- thenoyl)acetonato, PBO = 2-(2′-pyridyl)-1,3-benzoxazole, and PBT = 2-(2′-pyridyl)-1,3-benzothiazole], have been synthesized. [Eu(TTA) 3(PBO)] has been structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) A, β = 110.922(2)°, Z = 8. The EuIII ion is eight-coordinate, with three bidentate TTA- anions and one bidentate N,O-chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)3(PBO)] and [Eu-(TTA)3(PBT)] are reported as well. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
The synthesis of azo compounds from nitro compounds using lead and triethylammonium formate
Alloum, Abdelkrim Ben,Bougrin, Khalid,Soufiaoui, Mohamed
, p. 5935 - 5937 (2003)
Chemoselective synthesis of benzimidazoles in good yield was achieved with a variety of aldehydes in heterogeneous media. This efficient procedure has been developed for the condensation of ortho-phenylene-diamine with aldehydes by silica-supported thionyl chloride in dichloromethane at ambient temperature.
Photophysics of Three Pyridylbenzimidazoles in Solution
Brown, Robert G.,Entwistle, Neil,Hepworth, John D.,Hodgson, Kevin W.,May, Bernadette
, p. 2418 - 2420 (1982)
Fluorescence decay time data are presented for the three benzimidazoles with pyridine substituted at the 2 position.The anomalous behavior of 2-(2'-pyridyl)benzimidazole in alcohols is explained in terms of the alcohol facilitating hydrogen transfer from the imidazole ring to the pyridine nitrogen atom.The rate constants for this process have been evaluated by studying the quenching of the fluorescence of 2-(2'-pyridyl)benzimidazole in cyclohexane by ethanol.
Imidazolium chloride-catalyzed synthesis of benzimidazoles and 2-substituted benzimidazoles from o-phenylenediamines and DMF derivatives
Gan, Zongjie,Tian, Qingqiang,Shang, Suqin,Luo, Wen,Dai, Zeshu,Wang, Huajun,Li, Dan,Wang, Xuetong,Yuan, Jianyong
, p. 7450 - 7456 (2018)
A facile, general, and economical synthesis of diversely functionalized benzimidazoles and 2-substituted benzimidazoles has been realized via the imidazolium chloride-catalyzed cyclization of o-phenylenediamines with DMF derivatives. This protocol shows a broad substrate scope for aliphatic, aromatic, and heteroaromatic amides. A series of benzimidazoles and 2-substituted benzimidazoles have been obtained in moderate to excellent yields.
Amide-imine conjugate involving gallic acid and naphthalene for nano-molar detection, enrichment and cancer cell imaging of La3+: Studies on the catalytic activity of the La3+complex
Shaikh, Ahad,Ghosh, Milan,Mukherjee, Pallabi,Ghosh, Avijit,Molla, Rostam Ali,Ta, Sabyasachi,Das, Debasis
, p. 13501 - 13506 (2020)
A single crystal X-ray structurally characterized amide-imine conjugate (GAN) derived from gallic acid and naphthalene selectively recognizes La3+ ions via TURN ON fluorescence through ESIPT and CHEF mechanisms. GAN can detect as low as 23.93 × 10-9 M La3+ ions and image intracellular La3+ ions in live HeLa and SiHa cells under a fluorescence microscope in a time- and concentration dependent manner. The corresponding [La(iii)-GAN] complex is established as an efficient catalyst for the synthesis of benzimidazole derivatives from o-phenylenediamine and substituted benzaldehydes. Moreover, GAN is very useful for enrichment of La3+ in ethyl acetate medium. This journal is
Synthesis and antiinflammatory activity of some 2-(substituted-pyridinyl)benzimidazoles
Tsukamoto,Yoshino,Kohno,Ohtaka,Kagaya,Ito
, p. 734 - 738 (1980)
A series of 2-(2-pyridinyl)benzimidazoles was synthesized and evaluated for antiinflammatory activity by the carrageenan-induced rat paw edema assay. Among several active derivatives, 2-(5-ethylpyridin-2-yl)benzimidazole was selected for further study. A comparison of this compound with phenylbutazone and tiaramide revealed that it possesses stronger activity in acute inflammatory models possibly with slightly less gastrointestinal irritation than both phenylbutazone and tiaramide.
Electrocatalytic CO2 Reduction with a Half-Sandwich Cobalt Catalyst: Selectivity towards CO
Kumar Pandey, Indresh,Kumar, Abhishek,Choudhury, Joyanta
, p. 904 - 909 (2020)
We present herein a Cp*Co(III)-half-sandwich catalyst system for electrocatalytic CO2 reduction in aqueous acetonitrile solution. In addition to an electron-donating Cp* ligand (Cp=pentamethylcyclopentadienyl), the catalyst featured a proton-responsive pyridyl-benzimidazole-based N,N-bidentate ligand. Owing to the presence of a relatively electron-rich Co center, the reduced Co(I)-state was made prone to activate the electrophilic carbon center of CO2. At the same time, the proton-responsive benzimidazole scaffold was susceptible to facilitate proton-transfer during the subsequent reduction of CO2. The above factors rendered the present catalyst active toward producing CO as the major product over the other potential 2e/2H+ reduced product HCOOH, in contrast to the only known similar half-sandwich CpCo(III)-based CO2-reduction catalysts which produced HCOOH selectively. The system exhibited a Faradaic efficiency (FE) of about 70percent while the overpotential for CO production was found to be 0.78 V, as determined by controlled-potential electrolysis.
Novel dye sensitizers of main chain polymeric metal complexes based on complexes of 2-(2′-pyridyl)benzimidazole derivative with Zn(II), Co(II): Synthesis, characterization, and photovoltaic performance for dye-sensitized solar cells
Peng, Dahai,Zhang, Wei,Tang, Guipeng,Zhou, Jun,Hu, Jiaomei,Xie, Qiufang,Zhong, Chaofan
, p. 397 - 404 (2015)
In this paper, four novel D-π-A polymeric metal complex as dye sensitizers for dye-sensitized solar cell, which have Poly(p-phenylenevinylene) or carbazole derivative used as an electron donor, thiophene derivatives used as π-bridge and 2-(2′-pyridyl)benzimidazole derivative metal (Zn, Co) complex used as an electron acceptor (A) were synthesized and characterized. They have been determined and studied by FT-IR, TGA, DSC, GPC, elemental analysis, UV-vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry, J-V curves and IPCE plots. The results show that four novel polymeric metal complex exhibited good photovoltaic property and thermal stability. The DSSC fabricated by P1, P2, P3 and P4 exhibit good device performance with a power conversion efficiency of up to 2.15, 2.27, 2.30 and 2.41 % (under simulated air mass 1.5 G irradiation) respectively, indicating the polymeric metal complexes are promising in the development of DSSC.
Concentrated solar radiation promoted unconventional greener approach: Solvent-free benign synthesis of functionalized benzimidazoles
Harsh, Simran,Yusuf, Mohamad,Sharma, Rohit,Kumar, Yogesh,Kumar, Rupesh
, p. 119 - 130 (2018)
Renewable concentrated solar-radiation (CSR) offered a promising en route for the development of practical, highly efficient, scalable, catalyst free and solvent-free clean process leading to the synthesis of functionalized benzimidazoles. Developed protocol has a very good substrate scope, involves mild reaction conditions and products obtained in good to excellent yields. Method presented the observations in which light alone could affect the remarkable changes with more than 85% energy saving and 75% less reaction time in listed organic transformations.
Structure-activity relationships in cytotoxic AuI/Au III complexes derived from 2-(2′-pyridyl)benzimidazole
Maiore, Laura,Aragoni, Maria Carla,Deiana, Carlo,Cinellu, Maria Agostina,Isaia, Francesco,Lippolis, Vito,Pintus, Anna,Serratrice, Maria,Arca, Massimiliano
, p. 4068 - 4080 (2014)
Gold(I) and gold(III) complexes derived from 2-(2′-pyridyl) benzimidazole (pbiH) were proven to be a promising class of in vitro antitumor agents against A2780 human ovarian cancer cells. In this paper, a comparative electrochemical, UV-vis absorption, and emission spectroscopic investigation is reported on pbiH, the two mononuclear AuIII complexes [(pbi)AuX 2] (X = Cl (1), AcO (2)), the four mononuclear AuI derivatives [(pbiH)AuCl] (3), [(pbiH)Au(PPh3)]PF6 ((4 +)(PF6-)), [(pbi)Au(PPh3)] (5), and [(pbi)Au(TPA)] (6), the three mixed-valence AuIII/AuI complexes [(μ-pbi)Au2Cl3] (7), [(Ph3P) Au(μ-pbi)AuX2]PF6 (X = Cl ((8+)(PF 6-)), AcO ((9+)(PF6-))), and the binuclear AuI-AuI compound [(μ-pbi)Au 2(PPh3)2]PF6 ((10 +)(PF6-)). All complexes feature irreversible reduction processes related to the AuIII/AuI or Au I/Au0 processes and peculiar luminescent emission at about 360-370 nm in CH2Cl2, with quantum yields that are remarkably lower ((0.7-14.5) × 10-2) in comparison to that determined for the free pbiH ligand (31.5 × 10-2) in the same solvent. The spectroscopic and electrochemical properties of all complexes were interpreted on the grounds of time-dependent PBE0/DFT calculations carried out both in the gas phase and in CH2Cl2 implicitly considered within the IEF-PCM SCRF approach. The electronic structure of the complexes, and in particular the energy and composition of the Kohn-Sham LUMOs, can be related to the antiproliferative properties against the A2780 ovarian carcinoma cell line, providing sound quantitative structure-activity relationships and shedding a light on the role played by the global charge and nature of ancillary ligands in the effectiveness of Au-based antitumor drugs.
[Diaquo{bis(p-hydroxybenzoato-κ1O1)}(1-methylimidazole- κ1N1)}copper(II)]: Synthesis, crystal structure, catalytic activity and DFT study
Brahman, Dhiraj,Chhetri, Sailesh,Kamath, Amarjit,McArdle, Patrick,Sinha, Biswajit
, (2021/09/04)
Metal-organic hybrid complexes often exhibit large surface area, pore volume, fascinating structures and potential applications including catalytic applications. Hence a new metal-organic hybrid complex [Diaquo{bis(p-hydroxybenzoato-κ1O1)}(1-methylimidazole- κ1N1)}copper(II)] was synthesized using conventional method. Physico-chemical characterization of the complex was performed with FTIR spectroscopy, single crystal X-ray diffraction, TGA, EPR and FESEM. Single crystal X-ray diffraction study suggests it to be three dimensional with space group P212121 (orthorhombic). The crystal achieves its three-dimensional structure and stability through extensive intermolecular hydrogen bonding. Hirshfeld surface analysis, catalytic activity and DFT study of the complex was also performed. The synthesized complex acts as good catalyst in benzimidazole synthesis with good recyclability as catalyst up to 5th run.
s-Tetrazine-functionalized hyper-crosslinked polymers for efficient photocatalytic synthesis of benzimidazoles
An, Wan-Kai,Zheng, Shi-Jia,Zhang, Hui-Xing,Shang, Tian-Tian,Wang, He-Rui,Xu, Xiao-Jing,Jin, Qiu,Qin, Yuchen,Ren, Yunlai,Jiang, Song,Xu, Cui-Lian,Hou, Mao-Song,Pan, Zhenliang
supporting information, p. 1292 - 1299 (2021/02/26)
Developing green-safe, efficient and recyclable catalysts is crucial for the chemical industry. So far, organic photocatalysis has been proved to be an environmentally friendly and energy-efficient synthetic technology compared with traditional metal catalysis. As a versatile catalytic platform, hyper-crosslinked polymers (HCPs) with large surface area and high stability are easily prepared. In this report, we successfully constructed two porous HCP photocatalysts (TZ-HCPs) featurings-tetrazine units and surface areas larger than 700 m2g?1through Friedel-Crafts alkylation reactions. The rational energy-band structures and coexisting micro- and mesopores endow TZ-HCPs with excellent activities to realize the green synthesis of benzimidazoles (28 examples, up to 99% yield, 0.5-4.0 h) in ethanol. Furthermore, at least 21 iterative catalytic runs mediated by TZ-HCP1D were performed efficiently, with 96-99% yield. This study of TZ-HCPs sheds light on the wide-ranging prospects of application of HCPs as metal-free and green photocatalysts for the preparation of fine chemicals.
Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen
Wei, Lanfeng,Wei, Yu,Xu, Liang,Zhang, Jinli
supporting information, p. 4446 - 4450 (2021/06/30)
The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.
