Triaryl Imidazole Research Articles

One–Pot Three–Component Synthesis of 2,4,5–Triaryl Imidazoles using Fe3O4@BisImid−CuBr Nanocomposite as an Ecofriendly and Efficient Magnetically Reusable Catalyst

AbstractImidazoles are one of the keys of N‐heterocycle molecules that exist in the structure of many biomolecules. In this research project, we reported that Fe3O4@BisImid−CuBr nanocomposite is an attractive and efficient nanomagnetic catalyst to afford 2,4,5–triaryl imidazoles through reactions of 1,2–diketones and aldehydes in the presence of NH4OAc under ecofriendly conditions. The Fe3O4@BisImid−CuBr nanocomposite was readily fabricated by a simple method from available reagents and its structure was analyzed by spectroscopic techniques. SEM and TEM images affirmed the formation of particles in spherical shape and nanometer–size. Under this methodology, a diverse library of triaryl imidazoles were afforded with high yields in water. This synthetic methodology has significant features such as (a) high yields and high purity of the products (b) suitable reaction time (c) use of magnetic reusable nanocatalyst (d) high reusability of Fe3O4@BisImid−CuBr nanocatalyst and the performance of reactions in aqueous medium.

EMIm][BH3CN] Ionic Liquid as an Efficient Catalyst for the Microwave- Assisted One-Pot Synthesis of Triaryl Imidazole Derivatives

Abstract: In this present investigation, efficient and general protocols for the synthesis of a series of imidazoles 4(a-p) derivatives have been developed by cyclocondensation of aromatic aldehydes, benzil and ammonium acetate in the existence of efficient [EMIm][BH3CN] ionic liquid catalyst under microwave condition in good to excellent yields (91-97%). The structures of the synthesized compounds have been confirmed by IR and NMR spectra. The significant features of this protocol are an uncomplicated workup process, rate enhancement with high yields, and efficient catalysts. It was concluded that [EMIm][BH3CN] is the finest catalyst under MW heating conditions.

Fe3O4@Diamine-CuI Nanocomposite: A Novel and Highly Reusable Nanomagnetic Catalyst for Ecofriendly Synthesis of Triaryl Imidazoles

Molecules that have an imidazole ring in their structure show different biological effects, the most important of which are antifungal, antibacterial, and medical properties. In this paper, we reported that copper (I) iodide supported on the surface of magnetic Fe3O4 nanoparticles modified with 3,4-diaminobenzoic acid [Fe3O4@Diamine-CuI] is a new, recoverable, and highly efficient nanocatalyst for the preparation of 2,4,5-trisubstituted imidazoles through the one-pot three-component reaction of aromatic aldehydes with benzil and ammonium acetate as the nitrogen source at refluxing water. The structure of the as-constructed Fe3O4@Diamine-CuI nanomaterial is well characterized by FT-IR spectroscopy, SEM, EDX, TEM, XRD, VSM, EDX elemental mapping, and ICP-OES techniques. It is worth mentioning that the Fe3O4@Diamine-CuI nanocatalyst was easily separated from the reaction medium using a magnetic magnet and could be reused for 8 times without reducing its catalytic activity. The advantages of this catalytic system include ecofriendly conditions, easy separation of the catalyst, ability to recycle the catalyst, low cost, very short reaction time, water as the solvent, and simple purification of the products.

One-pot synthesis, spectral characterization, biological evaluation, molecular docking studies and in silico ADME/Tox profiling of new 2,4,5 triaryl imidazole derivatives as anti tubercular agents

BackgroundTuberculosis still looms large on the global epidemiological radar and warrants continuous effort in the direction of developing new anti TB drugs to battle evolving resistance mechanisms of the causative agent Mycobacterium tuberculosis. MethodsIn the present paper, synthesis of n has been attempted. All the synthesized compounds were characterized by 1H-NMR, 13C-NMR, IR and Mass spectroscopy. Anti TB profile of the synthesized compounds were tested by MABA assay employing M.tb H37Rv strain. ResultsTwo compounds namely N-(2-acetoxy)-N-methyl-4-(4,5-diphenyl-1H-imidazole-2-yl) benzenamine and 2-(N-(4-(4,5-bis(4-methoxyphenyl)-1H-imidazole-2-yl)phenyl)-N-methylamino) ethanol exhibited impressive anti TB inhibitory potential with an MIC of 3.125 μg/mL. To visualize the binding interactions of the active compounds molecular docking studies were carried out on putative target M. tuberculosis Glutamine synthetase (MtGS) in complex with a trisubstituted imidazole. To ascertain their drug likeliness and safety profile in silico ADME/T prediction was performed on all the synthesized compounds. ConclusionThree compounds 1a, 2g and 2c exhibited good inhibitory potency against M.tb H37Rv and all the synthesized compounds also show promising antifungal activity.

Design, Synthesis, Biological Evaluation, and Computational Studies of Novel Tri-Aryl Imidazole-Benzene Sulfonamide Hybrids as Promising Selective Carbonic Anhydrase IX and XII Inhibitors.

A novel series of tri-aryl imidazole derivatives 5a–n carrying benzene sulfonamide moiety has been designed for their selective inhibitory against hCA IX and XII activity. Six compounds were found to be potent and selective CA IX inhibitors with the order of 5g > 5b > 5d > 5e > 5g > 5n (Ki = 0.3–1.3 μM, and selectivity ratio for hCA IX over hCA XII = 5–12) relative to acetazolamide (Ki = 0.03 μM, and selectivity ratio for hCA IX over hCA XII = 0.20). The previous sixth inhibitors have been further investigated for their anti-proliferative activity against four different cancer cell lines using MTT assay. Compounds 5g and 5b demonstrated higher antiproliferative activity than other tested compounds (with GI50 = 2.3 and 2.8 M, respectively) in comparison to doxorubicin (GI50 = 1.1 M). Docking studies of these two compounds adopted orientation and binding interactions with a higher liability to enter the active side pocket CA-IX selectively similar to that of ligand 9FK. Molecular modelling simulation showed good agreement with the acquired biological evaluation.

Electrochromism of fast photochromic radical complexes forming light-unresponsive stable colored radical cation.

We demonstrated the electrochromism of photochromic radical complexes containing triaryl imidazole: fast photoswitchable pentaarylbiimidazole (PABI) and the phenoxyl-imidazolyl radical complex (PIC). Cyclic voltammetry and spectroelectrochemistry revealed that PABI and PIC generate the highly stable radical cation by one-electron oxidation accompanied by a color change from colorless to green. The stability of the radical cation is strongly affected by the dihedral angle between the imidazole ring and the phenyl ring at the 2-position of the imidazole ring.

Fly Ash Catalyzed Microwave Assisted Multicomponent Synthesis of Trisubstituted Imidazole Derivatives

Background: Imidazoles are important class of heterocyclic compounds showing biological activities. Several methods have been investigated till today for the synthesis of triaryl imidazoles. Some of these classical as well as nonclassical methods experiences drawbacks for instance elongated reaction time, expensive catalyst, low yield of product etc. Hence improvement of a competent method is still necessary. This paper reveals greener protocol for the synthesis of triaryl imidazoles by cyclocondensation of aromatic aldehydes, benzil and ammonium acetate in existence of fly ash as an efficient heterogeneous catalyst by means of microwaves. Methods: Heterogeneous catalyst fly ash was prepared by simple thermal activation method. The catalyst was systematically characterized through wet chemical analysis, XRD, FT-IR, SEM and EDS. The structural analysis was done using XRD and IR. Morphological study was performed using SEM and elemental composition studied by EDS technique. This activated fly ash catalyst was applied in the synthesis of trisubstituted imidazoles. The progress of reaction was checked by TLC and the synthesized compounds were further confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy. Results: To check feasibility of activated fly ash for trisubstituted imidazole synthesis, reactions under microwave irradiation employed. The products were obtained in higher yield (92-98%). Conclusion: The fly ash was found to be highly effective in the synthesis of trisubstituted imidazoles under microwave irradiation. The significant features of this protocol are rate enhancement, uncomplicated work up process, high yields and employ of ecofriendly catalyst. Keywords: Wet chemical analysis, microwave, fly ash, heterogeneous, catalyst, imidazole.

“ON-OFF” novel fluorescent chemosensors based on nanoaggregates of triaryl imidazoles for superselective detection of nitro-explosive trinitrophenol in multiple solvent systems

Novel fluorescent chemosensors with a triaryl-substituted imidazole (TAI) moiety were synthesized, which exhibited strong fluorescence. These fluorescent chemosensors allowed highly sensitive and selective detection of nitroaromatic explosive, trinitrophenol (TNP). The TAI were successfully transformed to fluorescent organic nanoparticles (FONPs) in aqueous medium using re-precipitation method thus enabling fluorescent based detection of TNP in aqueous medium also. We hereby present simple and selective chemosensors that are highly sensitive towards TNP and not-sensitive towards interfering analytes. In light of Stern-Volmer plots, Benesi–Hildebrand plots and 1H NMR titrations; it was confirmed that there exist competent interactions between the chemosensors and TNP. A detailed study revealed that synergistic effect of photo-induced electron transfer, electrostatic interaction and inner filter effect resulted in fluorescence quenching of chemosensors on the addition of TNP. The compounds are practically applicable for sensing TNP in real environmental samples as they gave good sensing response towards TNP in pH range of 5–9. Fluorescent test strips were fabricated which allowed effective on-site visual detection of explosive compound (TNP). To the best of our knowledge, this chemosensor represents the first example of TNP detection in aqueous medium using FONPs of TAI.

Synthesis of aromatic, soluble, and thermally stable polyamides derived from new diamine containing unsymmetrical phenolphthalein and imidazole pendent group

A novel diamine monomer containing unsymmetrical phenolphthalein and triaryl imidazole pendant group, 3,3-bis(4-(4-amino-2-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy)phenyl)isobenzofuran-1(3H)-one (BADPPI), was successfully prepared in three steps. The novel diamine monomer BADPPI was directly polymerized with commercially available diacids, such as terephthalic acid, isophthalic acid, pyridine-2,6-dicarboxylic acid, and adipic acid, to obtain corresponding polyamides (PAs). The resulting novel aromatic PAs were obtained in high yields and moderate inherent viscosities in the range of 0.52–0.57 dL g−1 and exhibited excellent solubility in aprotic polar solvents, such as N,N-dimethylacetamide , N-methyl-2-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, meta cresol, and pyridine. PAs showed high glass-transition temperatures between 191°C and 277°C. Thermogravimetric analysis of the PAs indicated a 10% weight loss ( T10%) in the temperature range of 382–473°C and char yields at 600°C under nitrogen atmosphere in the range of 56–70% depending on the diacids monomer used for the PAs preparation.

One Pot Multicomponent Green Synthesis of Triaryl Imidazoles Catalysed by Nano Nickel Cobalt Ferrite

One Pot Multicomponent Green Synthesis of Triaryl Imidazoles Catalysed by Nano Nickel Cobalt Ferrite

Preparation and characterization of polyimides containing triaryl imidazole side groups

A novel triaryl imidazole‐containing diamine, 3,5‐diamino‐N‐(4‐(4,5‐diphenyl‐1H‐imidazol)phenyl)benzamide, was successfully synthesized via the condensation of 4‐(4,5‐diphenyl‐1H‐imidazol)benzenamine and 3,5‐dinitrobenzoyl chloride, followed by reduction of the dinitro compound. A series of new aromatic polyimides with pendent triaryl imidazole moieties were prepared from the reaction of this diamine with various tetracarboxylic dianhydrides by a conventional two‐step polymerization process via thermal and chemical imidizations. The polyimides were obtained in quantitative yields with inherent viscosities of 0.21–0.44 dL/g. All the polymers are readily soluble in polar organic solvents. Flexible and strong films of polyimides were obtained by solution casting. The glass transition temperature of these polymers was in the range of 261–264°C. They were fairly stable up to a temperature around 300°C and lost 10% weight at 408°C under nitrogen. The ultraviolet–visible absorption spectra showed that all of the polymers had absorption maxima around 320 nm with a fluorescence emission maxima around 388–407 nm in N‐methyl‐2‐pyrrolidinone solution. Cyclic voltammograms of the polyimides revealed an oxidation wave with a peak around 1.7 V. Copyright © 2016 John Wiley & Sons, Ltd.

Chitosan impregnation with biologically active tryaryl imidazoles in supercritical carbon dioxide.

The presented paper is focused on impregnation of chitosan and its derivatives with a biologically active triaryl imidazole model compound ((2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole) in the supercritical carbon dioxide medium. Since initial chitosan represents a polycation-exchange resin and does not swell in supercritical carbon dioxide, the impregnation was carried out in the presence of water (0.15-3.0 vol%). The maximum 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole concentration in a chitosan film was achieved at the ~5 × 10(-3) g/cm(3) water content in the reactor. We also used hydroxy carboxylic acid derivatives of chitosan and its copolymer with polylactide as matrices for introduction of hydrophobic 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole. We have shown that unmodified chitosan contains the greatest amount of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole, as compared with its hydrophobic derivatives. The kinetics of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole diffusion from a chitosan matrix was studied in acidified water with pH 1.6. We found that the complete release of 2-2-hydroxyphenyl)-4.5-diphenyl-1H-imidazole into the aqueous phase from unmodified chitosan films occurred in 48 h, while its complete release from chitosan modified with hydroxy carboxylic acids occurred in 5 min or less.

A comparative study of organic electron transfer redox mediators: electron transfer kinetics for triarylimidazole and triarylamine mediators in the oxidation of 4-methoxybenzyl alcohol

The triarylimidazoles (TAIs) constitute a promising class of organic electron transfer redox mediators that have been used to achieve indirect electrochemical C-H bonds activation and functionalization. Herein we report the diffusion and electron transfer rates for the oxidation of 4-methoxybenzyl alcohol using TAI and compare its electrochemical behavior with that of tris(4-bromophenyl)amine (TBPA). The results contribute to our understanding of the electron transfer process of electrocatalytic oxidation using TAIs, and offer useful guidelines for their further development and use.

Synthesis and characterization of organosoluble polyetherimides with bulky triaryl imidazole moiety: Study of photophysical properties and kinetic of thermal degradation

Novel fluorescent polyetherimides containing bulky triaryl imidazole pendant and ether linkage in the main chains were prepared from a diamine, 2,2-phenoxy-bis[4-amino-2(4,5-diphenyl-2H-imidazole-2-yl)]propane, and commercially available dianhydrides. All the resulting polymers were amorphous with inherent viscosities ranged from 0.45 to 0.75 dl/g and were readily soluble in many organic solvents which could be solution-cast into transparent and tough films. They had useful levels of thermal stability associated with relatively high T g (245–254°C), 10% weight loss temperatures in excess of 500°C, and char yields at 600°C in air up to 62%. These polymers exhibited strong UV-vis absorption maxima in solution and in solid state. Photoluminescence efficiency of the polyetherimides was affected by their chemical structure with quantum yields in the range 10–28%.

Synthesis and characterization of organo-soluble polyamides containing triaryl imidazole pendant and ether linkage moieties: thermal, photophysical, and chemiluminescent properties

A new symmetrical diamine monomer containing a triaryl imidazole pendant group was successfully synthesized by the nucleophilic substitution of hydroquinone with the synthesized 2-(2-chloro-5-nitrophenyl)-4, 5-diphenyl-1H-imidazole (I). A series of novel polyamides were prepared from the diamine monomer and various aliphatic and aromatic dicarboxylic acids via phosphorylation polyamidation. These polyamides are readily soluble in many organic solvents; their inherent viscosities ranged from 0.68 to 0.89 dl/g and gave tough and flexible films by solution-casting. They had useful levels of thermal stability associated with relatively high Tgs (186–278°C), 10% weight loss temperatures in the range of 355–482°C, and char yields at 600°C in air up to 67%. All the polyamides have fluorescence emission in dilute (0.2 g/dl) DMAc solution with maxima at 425–495 nm and with the quantum yields in the range 14–28%. The chemiluminescence activity of polyamides was also studied in the presence of peroxyoxalate. Copyright © 2010 John Wiley & Sons, Ltd.

Synthesis and identification of organosoluble polyamides bearing a triaryl imidazole pendent: Thermal, photophysical, chemiluminescent, and electrochemical characterization with a modified carbon nanotube electrode

Abstract A novel monomer containing a triaryl imidazole pendent group was successfully synthesized by nucleophilic substitution of bisphenol A with 2-(2-chloro-5-nitrophenyl)-4,5-diphenyl-1H-imidazole (I). A series of new polyamides (PAs) with inherent viscosities of 0.95–1.2 dL/g was prepared by direct polycondensation of the diamine with various dicarboxylic acids. These PAs were readily soluble in many organic solvents and gave tough and flexible films by solution casting. These PAs exhibited Tgs between 189 °C and 252 °C, and 10% weight loss temperatures in excess of 400 °C with up to 68% char yield at 600 °C in air. All of the PAs emitted a greenish-yellow light in dilute THF solution, with photoluminescence (PL) quantum yields in the range of 10–25%. The chemiluminescent activity and electrochemical oxidation of the PAs were also investigated.

Synthesis of organosoluble polyamides with bulky triaryl imidazole pendent group

New unsymmetrical diamine monomer containing triaryl imidazole pendent group, 4-[4-(4,5-diphenyl-1 H-imidazol-2-yl)phenoxy]-1,3-benzenediamine, was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5-diphenyl-1 H-imidazol-2-yl)phenol, followed by palladium-catalyzed hydrazine reduction. This new monomer was further confirmed by FT-IR, 1H NMR and 13C NMR. Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of four commercially aromatic dicarboxylic acids with the prepared diamine. Inherent viscosities of polyamides were in the range 0.42–0.53 dL/g indicating formation of medium molecular weight polymers. Polyamides exhibited glass-transition temperature ( T g) in the range 236–265 °C. These polymers are essentially amorphous and were soluble in polar aprotic solvents such as DMF, NMP, DMAc. The 10% weight loss temperatures in air atmosphere, measured by TGA were in the range 350–373 °C indicating their good thermal stabilities.

Synthesis of soluble and thermally stable polyimides from unsymmetrical diamine containing 2,4,5-triaryl imidazole pendent group

A novel unsymmetrical diamine monomer containing triaryl imidazole pendant group, 4-[4-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy] benzene-1,3-diamine (DAI), was successfully synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5-diphenyl-1 H-imidazol-2-yl)phenol, followed by palladium-catalyzed hydrazine reduction. The diamine monomer DAI polymerized with commercial available dianhydrides such as benzophenone tetracarboxylic dianhydride (BTDA), pyromellitic dianhydride (PMDA) and bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA) by using two step synthetic methods to obtain corresponding polyimides (PIs). PIs had inherent viscosity of 0.42–0.51 dL/g and exhibited excellent solubility in aprotic polar solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), pyridine and methyl sulfoxide (DMSO). PIs showed high glass transition temperatures between 230 and 320 °C, and they were fairly stable up to a temperature above 300 and 450 °C depending on the dianhydride monomer used for the PIs preparation.

Quantitative Structure-Activity Relationships of Selective Antagonists of Glucagon Receptor Using QuaSAR Descriptors

In the present paper, quantitative structure activity relationship (QSAR) approach was applied to understand the affinity and selectivity of a novel series of triaryl imidazole derivatives towards glucagon receptor. Statistically significant and highly predictive QSARs were derived for glucagon receptor inhibition by triaryl imidazoles using QuaSAR descriptors of molecular operating environment (MOE) employing computer-assisted multiple regression procedure. The generated QSAR models revealed that factors related to hydrophobicity, molecular shape and geometry predominantly influences glucagon receptor binding affinity of the triaryl imidazoles indicating the relevance of shape specific steric interactions between the molecule and the receptor. Further, QSAR models formulated for selective inhibition of glucagon receptor over p38 mitogen activated protein (MAP) kinase of the compounds in the series highlights that the same structural features, which influence the glucagon receptor affinity, also contribute to their selective inhibition.

An Efficient Synthesis of 2,4,5-Trisubstituted and 1,2,4,5-Tetrasubstituted-1H-imidazoles

Since the appearance of the first paper on the application of microwave irradiation in the chemical synthesis the approach has blossomed into a useful technique for a variety of applications in organic synthesis and functional group transformations. In moving towards sustainable technologies the focus has now shifted to less cumbersome solventless methods wherein solid supported microwave synthesis has played an important role. This technique eliminates the use of solvent during the reaction stage but requires an appreciable amount of solvent for the adsorption of reagents and elution of product. The emergence of neat reaction is a recent approach under the new paradigm of green chemistry where the neat reactants undergo facile reaction to provide high yield of pure products thus eliminating or minimizing the use of organic solvents. These no solvent reactions are not only advantageous for environmental reasons but also offer benefits of enhanced reaction rates, greater selectivity and experimental ease of manipulation. The imidazole ring system is of particular interest as it is a component of histidine that produces histamine in metabolic process. The potency and wide applicability of the imidazole pharmacophore can be attributed to its hydrogen bond donor-acceptor capability as well as its high affinity for metals which are present in many protein active sites (eg. Zn, Fe, Mg). Triaryl imidazoles are used in photography as photosensitive compounds. In addition, they are of interest because of their herbicidal, analgesic, fungicidal, antiinflammatory and antithrombotic activities. The original synthesis of imidazole utilized glyoxal, formaldehyde and ammonia and established that the formation of four N–C bonds was a viable route. Although classical methods were derived from this early success, the reactions suffered low yields, mixture of products and lack of generality. Synthetic methodology alternatives are many and varied and have resorted to harsh conditions (eg. the formamide synthesis, which requires excess reagents, H2SO4 as a condensing agent, 150-200 °C, 4-6 h, 40-90%). Also, reagents for these procedures are not readily available, a key deficiency for library synthesis. In continuation to our endeavour towards green chemistry and the biological importance of substituted imidazole derivatives we have developed an ecologically safe strategy for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole derivatives employing neat reaction conditions using MWI. Results and Discussion