Benzimidazolium Bromides Research Articles

Benzimidazolium bromide derivative inclusion complexes with native and modified beta-cyclodextrins

The interactions between four native and modified beta-cyclodextrins and a benzimidazolium bromide salt were analyzed through UV-Vis and NMR Spectroscopy. The new benzimidazolium salt was obtained by simple and efficient conversion of N-1 substituted 5,6-dimethylbenzimidazole with phenacyl bromide in acetone. In all cases, the complexes stoichiometry was 1:1, as determined from UV-Vis titrations. Based on the values for association constants, the strength of the interactions with benzimidazolium bromide was weakest with the methyl substituted beta-cyclodextrin and strongest with the sulfobutylether substituted beta-cyclodextrin. Through-space NOE experiments were used to investigate the structural aspects of inclusion process. The obtained NOE correlations indicate coexistence of two inclusion modes: one with the phenacyl group inside the cyclodextrin cavity and the second one with dimethyl-substituted benzene ring inside the cavity. The imidazole ring and the ethyl substituent have been proven to remain outside the cyclodextrin cavity in both inclusion modes.

New sugar-incorporated N-heterocyclic carbene precursors and their Ag(I) and Pd(II) complexes: Synthesis, characterization, and cytotoxicity studies

In the present work, a new series of sugar-incorporated N-heterocyclic carbene precursors namely 1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7a), 4-methyl-1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7b), 4,5-diphenyl-1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]imidazolium bromide (7c), and 1-(3,4,5-trimethoxybenzyl)-3-[2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl]benzimidazolium bromide (8) were synthesized by the direct reaction of the N-alkylated benzimidazoles with 2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxy)-ethyl bromide. Ag(I)–NHC complexes (9a-c, 10) of the abovementioned precursors were synthesized by in-situ reaction with Ag2O in light-excluded conditions. The transmetallation reaction technique was used to synthesize Pd(II)–NHC complexes (11a-c, 12) by the reaction of [PdCl2(MeCN)2] with corresponding Ag(I)–NHC complexes. All NHC precursors and their corresponding Ag(I) and Pd(II) complexes were spectrally characterized using 1H &13C NMR, and mass spectrometry. Further, Pd(II) complexes were evaluated for their anticancer activity against eight diverse cancer cell lines, namely; Pancreatic Adenocarcinoma (Capan-1), Colorectal Carcinoma (HCT-116), Glioblastoma (LN229), Lung Carcinoma (NCI-H1975), Acute Lymphoblastic Leukemia (DND-41), Acute Myeloid Leukemia (HL-60), Chronic Myeloid Leukemia (K562), and non-Hodgkin Lymphoma (Z138). Standard antineoplastic drugs docetaxel and etoposide were included as reference compounds. Among the tested complexes, complex 11c displayed broad activity against all tested cancer types, albeit at higher concentrations when compared to the reference drugs.

Size controlled, structural characterization and applications of glucopyranoside-based N-heterocyclic carbenes stabilized gold nanoparticles

N-heterocyclic carbenes (NHCs) have evidenced wonderful alternatives as surface ligands, while synthetic challenges have limited their application in chiral gold nanoparticles (AuNPs). To avoid using difficult-to-synthesize and light-sensitive NHC-Au(I) complex, we synthesized four glucopyranoside-based benzimidazolium bromide salts (1a–1d-Br) and their corresponding haloaurate(III) salts (2a–2d-AuCl4). Then, the first-generation sugar-substituted NHCs stabilized extra-small and ultra-stable chiral AuNPs (Au@NHCs-sugar NPs, 3a–3d-AuNPs) was synthesized though two mild, efficient, and operation-friendly one-pot chemical reduction methods. The obtained 3a–3d-AuNPs were characterized by UV–Vis, NMR, HR-TEM, TGA, CD, FT-IR, and XPS spectroscopy. The designed 3a–3d-AuNPs with core diameters ranging from 2.3 to 3.8 nm remained stable against glutathione for up to 24 h over a wide temperature range of 95 to −78 °C, and over 4 years in air. The absence of NCHN proton in 1H NMR and FT-IR of 3a–3d-AuNPs confirmed the formation of NHC-Au bond, and clearly showed that all acetyl groups, benzimidazolium heterocycle, and N-substituents maintained. XPS analyses revealed the presence of Au(0) and Au(I) in all Au@NHCs-sugar NPs. This result leads us to postulate that 3a–3d-AuNPs exhibit a monolayer of Au(I) surrounding an Au(0) core. These designed 3a–3d-AuNPs were studied for their self-assembly behavior, antibacterial activity against bacterium Xanthomonas citri susp. citri (Xcc), and catalytic activity towards the reduction of nitroarenes. All of them demonstrated strong antibacterial activity against Xcc with minimum inhibitory concentration value <0.03125 mg·mL−1.

New Pyrrole Derivatives as Promising Biological Agents: Design, Synthesis, Characterization, In Silico, and Cytotoxicity Evaluation.

The current study describes the synthesis, physicochemical characterization and cytotoxicity evaluation of a new series of pyrrole derivatives in order to identify new bioactive molecules. The new pyrroles were obtained by reaction of benzimidazolium bromide derivatives with asymmetrical acetylenes in 1,2-epoxybutane under reflux through the Huisgen [3 + 2] cycloaddition of several ylide intermediates to the corresponding dipolarophiles. The intermediates salts were obtained from corresponding benzimidazole with bromoacetonitrile. The structures of the newly synthesized compounds were confirmed by elemental analysis, spectral techniques (i.e., IR, 1H-NMR and 13C-NMR) and single-crystal X-ray analysis. The cytotoxicity of the synthesized compounds was evaluated on plant cells (i.e., Triticum aestivum L.) and animal cells using aquatic crustaceans (i.e., Artemia franciscana Kellogg and Daphnia magna Straus). The potential antitumor activity of several of the pyrrole derivatives was studied by performing in vitro cytotoxicity assays on human adenocarcinoma-derived cell lines (i.e., LoVo (colon), MCF-7 (breast), and SK-OV-3 (ovary)) and normal human umbilical vein endothelial cells (HUVECs). The obtained results of the cytotoxicity assessment indicated that the tested compounds had nontoxic activity on Triticum aestivum L., while on Artemia franciscana Kellogg nauplii, only compounds 2c and 4c had moderate toxicity. On Daphnia magna, 4b and 4c showed high toxicity; 2a, 2b, and 2c moderate to high toxicity; only 4a and 4d were nontoxic. The compound-mediated cytotoxicity assays showed that several pyrrole compounds demonstrated dose- and time-dependent cytotoxic activity against all tested tumor cell lines, the highest antitumor properties being achieved by 4a and its homologue 4d, especially against LoVo colon cells.

Pentafluorobenzyl-substituted benzimidazolium salts: Synthesis, characterization, crystal structures, computational studies and inhibitory properties of some metabolic enzymes

This work contains the synthesis and characterization of the pentafluorobenzyl-substituted benzimidazolium salts which N-heterocyclic carbene (NHC) precursors. All compounds were characterized by using 1H, 13C, and 19F NMR, FT-IR spectroscopy, and elemental analysis techniques. All the spectroscopy and elemental analysis data fully confirm the proposed formulas. In the synthesized compounds, the molecular structures of compounds 1-(2-methylbenzyl)-3-(2,3,4,5,6-pentafluorobenzyl)benzimidazolium bromide (1b), 1-(4-methylbenzyl)-3-(2,3,4,5,6-pentafluorobenzyl)benzimidazolium bromide (1d) and 1-(4-trifluoromethylbenzyl)-3-(2,3,4,5,6-pentafluorobenzyl)benzimidazolium bromide (1f) were enlightened by single crystal X-ray diffraction studies. After enzyme inhibition study, a new series of pentafluorobenzyl-substituted NHC precursors were determined to be highly potent inhibitors for acetylcholinesterase (AChE) enzyme and carbonic anhydrases (hCAs) isoenzymes. Ki values were found in the range of 7.20±1.31 to 28.26±5.72 nM for AChE , 10.25±0.93 to 40.93±3.89 nM toward hCA I as pervasive metal containing enzymes present in prokaryotes and eukaryotes, and 3.33±0.15 to 58.22±6.99 nM for hCA II as the key enzyme promising strategy for the treatment of neurological disorders such as Alzheimer's disease. The molecular docking study performed for compounds had higher potential inhibitory properties involved in a novel series of pentafluorobenzyl-substituted NHC precursors based on the binding energy and interaction types against AChE and hCAs.

Synthesis and Toxicity Evaluation of New Pyrroles Obtained by the Reaction of Activated Alkynes with 1-Methyl-3-(cyanomethyl)benzimidazolium Bromide.

A series of new pyrrole derivatives were designed as chemical analogs of the 1,4-dihydropyridines drugs in order to develop future new calcium channel blockers. The new tri- and tetra-substituted N-arylpyrroles were synthesized by the one-pot reaction of 1-methyl-3-cyanomethyl benzimidazolium bromide with substituted alkynes having at least one electron-withdrawing substituent, in 1,2-epoxybutane, acting both as the solvent and reagent to generate the corresponding benzimidazolium N3-ylide. The structural characterization of the new substituted pyrroles was based on IR, NMR spectroscopy as well as on single crystal X-ray analysis. The toxicity of the new compounds was assessed on the plant cell using Triticum aestivum L. species and on the animal cell using Artemia franciscana Kellogg and Daphnia magna Straus crustaceans. The compounds showed minimal phytotoxicity on Triticum rootlets and virtually no acute toxicity on Artemia nauplii, while on Daphnia magna, it induced moderate to high toxicity, similar to nifedipine. Our research indicates that the newly synthetized pyrrole derivatives are promising molecules with biological activity and low acute toxicity.

Anti-quorum sensing activity in Pseudomonas aeruginosa PA01 of benzimidazolium salts: electronic, spectral and structural investigations as theoretical approach

Quorum sensing (QS) is a system used in the expression of virulence factors by many pathogenic bacteria, and blockage of the system is seen as a new and effective strategy in combating with resistant bacteria. The inhibition effects of two benzimidazolium salts, namely 1-(2-methylbenzonitrile)-3-benzylbenzimidazolium bromide (2) and 1-(N-methylphthalimide)-3-(4-methylbenzyl)benzimidazolium bromide (3), on quorum sensing-related virulence factors such as pyocyanin, elastase, biofilm formation and swarming motility, which is an opportunistic pathogen Pseudomonas aeruginosa PA01, were investigated in this study. The results show that the compound 3 has a significant inhibition on biofilm formation with 94%. Furthermore, the compounds 2 and 3 reduced swarming motility by 64–69% as well as pyocyanin production by 49–64% in P. aeruginosa PA01 without preventing bacterial growth in the tested concentrations. HF, B3LYP and M06–2X methods were used with 3–21 g, 6–31 g, sdd basis sets to compare the chemical activity of the compounds. Theoretically, 1H NMR, 13C NMR and Infrared spectra of the compounds were calculated in the HF/6-31++g basis set. The biological activities of the relative compounds were theoretically studied against cancer proteins. Crystal structure of the BRCT repeat region from the breast cancer associated protein, ID: 1JNX, crystal structure of liver cancer protein, ID: 3WZE and crystal structure of lung cancer protein, ID: 5ZMA, were compared. In the docking studies, the best result was obtained with compound 2 against the lung cancer cell with a docking score parameter of −5.85. Communicated by Ramaswamy H. Sarma

Mononuclear silver(I)-N-heterocyclic carbene complexes with benzimidazole-2-ylidene ligands: synthesis, crystal structure analyses and comparative antibacterial studies

The synthesis, characterization and antibacterial studies of N-heterocyclic carbene (NHC) precursors and their respective silver(I)-NHC complexes are reported. Five non-symmetric benzimidazolium bromide salts were synthesized through the addition of N-alkylbenzimidazole and various alkylbromides. These n-butyl-n’-alkylbenzimidazolium bromide salts (alkyl = methyl, ethyl, pentyl, hexyl, heptyl) 1, 2 and 4–6 were further used as precursors to synthesize silver(I)-NHC complexes, 8, 9 and 11–13, respectively, via in situ deprotonation. In addition, 14 was synthesized from its reported precursor salt, 1-benzyl-3-butylbenzimidazolium bromide (7) through the same procedure. Complex 8 is present as monomeric cation in the form of [NHC-Ag-NHC]PF6, as illustrated by single crystal X-ray crystallography analyses. In order for a full series of antibacterial studies, 1-butyl-3-propylbenzimidazolium bromide, 3, and respective complex, 9, were synthesized according to the reported procedure. All benzimidazolium salts (1–7) and silver(I)-NHC complexes (8–14) were evaluated for antibacterial activities. All benzimidazolium salts show no antibacterial activities while all silver(I)-NHC complexes show lower activities against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 12600) compared to the standard antibiotic drug Amoxicillin. Nevertheless, these mononuclear silver(I)-NHC complexes show lower antibacterial activities compared to the reported dinuclear silver(I)-NHC complexes with the same substituents in the ligands.

Tri N-Heterocyclic Carbene Trinuclear Silver(I) complexes: Synthesis and In Vitro cytotoxicity studies

Synthesis of ethylene linked tris benzimidazolium bromide salts that serve as precursors for the tri-NHC ligands in the respective tri-NHC trinuclear silver(I) complexes is described (NHC = N-heterocyclic carbene). Different wingtip substituents were selected (benzyl, n-butyl, cyclopentyl, 2-methylene benzonitrile, n-decyl) to furnish five new tris benzimidazolium salts (1-5) and the respective tri-NHC trinuclear silver(I) complexes (6-10). The synthesized and characterized compounds (1-10) were evaluated for their cytotoxic potential on human colon, human breast and human epitheloid cervix cancer cell lines by determining their IC50 values and evaluating their antiproliferative activity against the selected cell lines. The tested compounds were found to be good anticancer agents against breast cancer and cervical cancer cell lines and selectively good anticancer agents for the human colon cancer cell line.

2-Amino- and 2-hydroxymethylbenzimidazolium bromides as protein tyrosine phosphatase 1В (PTP1В) inhibitors and other targets associated with diabetes mellitus

New 2-amino- and 2-hydroxymethylbenzimidazoles were synthesized and used to prepare the previously unknown 1,2,3-tri- and 1,2,3,5-tetrasubstituted benzimidazolium bromides with a biphenyl-containing substituent at the imidazole nitrogen atom. In some cases, these bromides exhibit activity against targets associated with diabetes mellitus. These compounds are strong protein tyrosine phosphatase 1B (PTP1B) inhibitors, exhibit chelating and antiglycation activity, but have no significant AT1 receptor antagonist activity. Hence, biphenyl-containing benzimidazolium derivatives can be considered as a basis for the development of new promising agents for the treatment of type 2 diabetes mellitus (DM2) and other diseases mediated by high phosphatase PTP1B activity.

Synthesis and Structural Investigation of Some Transition Metals Complexes of Benzimidazolium Bromide

The present work involves the synthesis of novel imidazolium salts of bromide in step-wise reactions which are started from preparation of 2,4-dimorpholine-6-(1H-benzimidazole-1-yl)-1,3,5-triazine (1) in potassium hydroxide and DMF solvent followed by substitution reactions with n-butyl bromide and n-octyl bromide to afford the new ligands names L1 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-butyl-1H-benzimidazol-3-ium bromide and L2 = 1-(2,4-dimorpholino-1,3,5-triazine-2-yl)-3-octyl-1Hbenimidazol-3-ium bromide. The new ligands were recrystallized from hot chloroform and the following of reactions completion were carried out by thin layer chromatography (TLC). The formula and structures of the two salts of benzimidazolium bromide were confirmed on the basis of measurements of (CHN) elemental analyses, FT-IR, NMR and EIMS spectroscopy. Furthermore the manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized from the direct reactions of their hydrated metal salts in methanol with the solutions of the ligands in chloroform in 1:1 mole ratio and the analytical data of atomic absorption spectroscopy and elemental analyses revealed the proposed formula of the solid metal complexes. The data obtained from FT-IR, UV-Visible spectra, molar conductivity and magnetic susceptibility measurements confirmed the octahedral environment around cobalt(II) ion in [CoL(H2O)2Cl2] and the tetrahedral geometry was adopted for manganese(II) and zinc(II) ions. However the square-planner structure was expected for the copper(II) and nickel(II) complexes in [MLCl2], M = Ni(II) and Cu(II) ions and L = L1 and L2 ligands. As well as the suitable and favourable active sites in the two ligands L1 and L2 were the two nitrogen atoms of morpholine rings which has been observed from FT-IR spectra and the kinetic stability of five-member ring up on chelation with the metal ions supported the conclusion of the symmetry.

Synthesis, structures and anticancer studies of symmetrically and non-symmetrically aliphatic nitrile functionalized silver(I)-N-heterocyclic carbene and palladium(II)-N-heterocyclic carbene complexes

The newly designed Ag(I)-NHC and Pd(II)-NHC complexes (where NHC = N-heterocyclic carbene) bearing symmetrically and unsymmetrically nitrile functionalized have been synthesized, starting from the corresponding aliphatic nitrile functionalized benzimidazolium bromide salts. The resulting aliphatic nitrile functionalized benzimidazolium salts (1 and 2) were subsequently deprotonated with the basic metal source Ag2O by in situ deprotonation technique to obtain a mononuclear Ag(I)-NHC complexes (3 and 4). The mononuclear Pd(II)-NHC complexes (5 and 6) were prepared via transmetalation from their respective Ag(I)-NHC complexes, respectively. All compounds were characterized by elemental analyses, FT-IR, 1H- and 13C-NMR. Single crystal structural studies of Ag(I)-NHC complex revealed that the Ag(I) ion exhibits a linear geometry of quasi-parallel pairs of aromatic benzimidazole planes. The synthesized compounds were then screened for potential cytotoxicity on breast cancer cell line (MCF-7), using MTT assay. All the Ag(I)-NHC complexes show better activity with IC50 values ranging from 3.7 – 4.1 µM, while Pd(II)-NHC complexes show the IC50 values ranging from 13.9 – 14.2 µM in comparison with the standard drug, Tamoxifen (IC50 = 11.2 µM). All the respective benzimidazolium salts, however were found to be inactive. The anticancer activity is corresponding to the increasing lipophilicity order of the complexes as 5 < 6 < 3 < 4 (0.49, 0.56, 1.25 and 1.27, respectively).

Removal of residual functionalized ionic liquids from water by ultrasound-assisted zero-valent iron/activated carbon

ABSTRACTNumerous applications of ionic liquids (ILs) are often accompanied by the generation of aqueous wastes. Due to the high toxicity and poor biodegradability of ILs, effective chemical treatment is of great importance for their removal from aqueous solution. In this work, an ultrasound-assisted zero-valent iron/activated carbon (US-ZVI/AC) micro-electrolysis technique was used to degrade residual functionalized ILs, 1-butyl-3-methyl benzimidazolium bromide ([BMBIM]Br) and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) in aqueous solution, and the degradation degree, degradation kinetics and possible degradation pathways were investigated. It was shown that the degradation of these functionalized ILs was highly efficient in the US-ZVI/AC system, and the degradation degree was as high as 96.1% and 92.9% in 110 min for [BMBIM]Br and [AMIM]Cl, respectively. The degradation of [BMBIM]Br could be described by the second-order kinetics model, and [BMBIM]+ was decomposed in two ways: (i) sequential cleavage of N-alkyl side chain of the cation produced three intermediates; (ii) the 2-positioned H atoms of the benzimidazolium ring were first oxidized, and then the imidazolium ring was opened. The degradation of [AMIM]Cl followed the first-order kinetics rule, and the 2,4,5-positioned H atoms of the imidazolium ring were oxidized to induce ring opening. In addition, the removal of total organic carbon was found to be >87%, which indicates that most of the ILs was mineralized in the degradation process. These results suggest that ultrasound-assisted ZVI/AC micro-electrolysis is highly effective for the removal of residual functionalized ILs from aqueous environment.

Synthesis and antimicrobial activity of bulky 3,5‐di‐tert‐butyl substituent‐containing silver–N‐heterocyclic carbene complexes

A series of novel benzimidazolium bromides containing bulky 3,5‐di‐tert‐butyl group were synthesized in high yields as N‐heterocyclic carbene (NHC) ligands. These NHC ligands were metallated with Ag2O under moderate conditions to give novel silver–NHC complexes. The structures of all compounds were characterized using 1H NMR, 13CNMR, infrared and elemental analysis techniques, which supported the proposed structures. The silver–NHC complexes were screened for their in vitro antimicrobial activities against the standard bacterial strains Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa and the fungal strains Candida albicans and C. tropicalis. The results showed that most of the silver–NHC complexes inhibited the growth of all bacterial strains and fungal strains and were found to display effective antimicrobial activity against different microorganisms.

New Pd-NHC PEPPSI complexes from benzimidazolium salts with a phenacyl group attached to N3

New benzimidazole-2-ylidene palladium(II) complexes of PEPPSI type, having pyridine as a throw-away ligand were obtained in one step from phenacyl benzimidazolium bromides and PdCl2. Although the presence of phenacyl groups attached to the N3 could lead in basic medium either to the N-heterocyclic carbenes or to the corresponding N-ylides, 6 new complexes were obtained without need of supplementary reactions steps or carbene transfer agents. X-ray diffraction analysis revealed that the expected chlorine atoms in the complexes were replaced by bromine atoms.

Dose‐, time‐and lipophilicity‐dependent silver(I)–N‐heterocyclic carbene complexes: Synthesis, characterization and interaction with plasmid and Aedes albopictus DNA

Four new Ag(I)–N‐heterocyclic carbene (NHC) complexes (5–8) bearing symmetrically substituted NHC ligands have been synthesized starting from the corresponding benzimidazolium bromide salts which are accessible in a single step from N‐substituted benzimidazoles (N‐alkyl and N‐aryl) and subsequently reacted with the basic metal source Ag2O in acetonitrile–methanol. These compounds were characterized using elemental analyses, 1H NMR, 13C NMR, Fourier transform infrared and UV–visible spectroscopic techniques, and molar conductivity. Single‐crystal structural studies for complex 5 show that the Ag(I) centre has a perfectly linear C–Ag–C coordination, with quasi‐parallel pairs of aromatic benzimidazole planes. All the complexes interact with Aedes albopictus DNA via intercalation mode by a large hypochromicity of 22 and 27% and smaller hypochromicity of 16 and 19%. Furthermore, all complexes exhibit efficient DNA cleavage activity via a non‐oxidative mechanistic pathway. The DNase activities of the test compounds revealed a time‐ and concentration‐dependent activity pattern. The Ag(I)–NHC complexes showed considerably higher DNA cleavage activity compared to their respective benzimidazolium salts at a lower concentration. The DNA cleavage of these complexes changed from a moderate effect to a good one, corresponding to the increasing lipophilicity order of the complexes as 5 &lt; 6 &lt; 7 &lt; 8 (1.02, 1.05, 1.78 and 2.06 for 5–8, respectively). This order is further corroborated with the DNA binding study, but with the exception of complex 5, which shows a better binding ability for DNA (Kb = 3.367 × 106) than complexes 6–8 (6.982 × 105, 8.376 × 105 and 1.223 × 106, respectively).

Synthesis and evaluation of novel $N,N'$-disubstituted benzimidazolium bromides salts as antitumor agents

Novel benzimidazolium bromides salts having (4-methoxyphenyl)ethyl, (phthalimide-2-yl)methyl, 4-nitro- benzyl, 2-phenylethyl, penthyl, or allyl groups were synthesized and their characterizations were conducted by $^{1}$H and $^{13}$C NMR and IR spectroscopic methods, and microanalysis. In vitro antitumor activities of the novel benzimidazole compounds (1-7) were determined by using ovarian (A2780) and prostate (PC-3) cancer cell lines. Antitumor properties of all compounds were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A time-dependent cell viability assay for the tested benzimidazole compounds was performed and the IC$_{50}$ values of the compounds were calculated after treatment for 24 and 48 h. Our results indicate that the tested benzimidazole compounds show antitumor activity against A2780 and PC-3 cell lines (P $

Formation of zwitterionic salts via three-component reaction of benzimidazolium bromides, aromatic aldehydes and 1,3-indanedione

The three-component reaction in ethanol in the presence of triethylamine as base catalyst resulted in the unusual charge-separated zwitterionic salts in good yields.

Synthesis, characterization, density function theory and catalytic performances of palladium(II)–N-heterocyclic carbene complexes derived from benzimidazol-2-ylidenes

1-Benzyl-3-ethylbenzimidazolium iodide (1) and 1-benzyl-3-(2′-nitrilebenzyl)benzimidazolium bromide (2) were prepared by the reaction of 1-benzylbenzimidazole with ethyl iodide or 2-bromomethylbenzonitrile to act as N-heterocyclic carbene (NHC) precursors. Bis-NHC silver(I) complexes having halide (3a and 4a) as well as hexafluorophosphate (3b and 4b) counterions were yielded by the reaction of NHC precursors with silver(I) oxide. Subsequent reactions of the silver(I) halide/hexafluorophosphate complexes with [PdCl2(CNCH3)2] in methanol afforded the NHC palladium(II) complexes (5 and 6) via carbene transfer method. All synthesized compounds were fully characterized by analytical and spectrometric methods. Preliminary catalytic studies evinced that the nitrile-functionalized palladium(II)–NHC complex 6 is highly active in the oxidation of 1-octene as well as styrene in the presence of aqueous hydrogen peroxide as an oxidizing agent. Both the olefins were oxidized to their corresponding oxidized products with 45–52% conversion with moderate selectivity in the presence of NHC palladium complexes, which acted as oxidation catalysts. In order to investigate the suggested structure of the title complexes, density functional theory was used to find the stable structures of the palladium complexes and their isomers. Geometry parameters, molecular orbital energies, electronic energy, band gap, and vibrational frequencies were calculated.

QSPR Study on the Melting Points of a Diverse Set of Potential Ionic Liquids by Projection Pursuit Regression

AbstractA Quantitative Structure–Property Relationship (QSPR) study was carried out to model the melting points for a diverse set of 288 potential Ionic Liquids (ILs) including pyridinium bromides, imidazolium bromides, benzimidazolium bromides, and 1‐substituted 4‐amino‐1,2,4‐triazolium bromides. Based on the calculated descriptors by CODESSA program, a Principal Component Analysis (PCA) was performed on the whole data to detect the homogeneities in the dataset and to assist the separation of the data into representative training and test sets. Heuristic Method (HM) and Projection Pursuit Regression (PPR) were used to develop linear and nonlinear models between the descriptors and the melting points. The PPR model gave a high predictive correlation coefficient (R2) of 0.810 and an Average of Absolute Relative Deviation (AARD) of 17.75%, which are better than those by HM model (R2=0.712, AARD=24.33%) indicating that PPR is better for the prediction of the melting points. In addition, the descriptors selected by HM can give some insight into factors that can affect the melting points, i.e., benzene ring structure, rotatable bonds, branching, symmetry, and intramolecular electronic effects. This information would be very useful in the design of the potential ILs with desired melting points.