Bromo Substitution Research Articles

Geometry Configuration and Bromo Substitution Effect of Terfluorenes on Amplified Spontaneous Emission Behaviors

Geometry Configuration and Bromo Substitution Effect of Terfluorenes on Amplified Spontaneous Emission Behaviors

Exploring the Electronic Influence of β‐Br Substitutions in CuTPP on Electrochemical Overall Water Splitting in Alkaline Medium

AbstractBeta substitution has a marked influence on the electronic environment of porphyrin ring atoms and the structure of the substituted porphyrin. In this work, we explore the influence of the bromo (Br) substitution at the β‐positions of copper tetraphenylporphyrin (CuTPP) and its consequent influence on the electrocatalytic alkaline overall water splitting. The β‐Br substitution is expected to exercise a strong influence on the electronic environment of central Cu through the electronic effects of Br. The overall influence of electronic effects is seen to lead to the net increase in the electron density of the central Cu (observed from XPS shifts) which is ultimately reflected in their different HER and OER performance in the alkaline medium. We observe the HER overpotentials (for 10 mA cm−2) of 697 mV, 760 mV, 838 mV, and 883 mV for the unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The OER performance on the contrary depicts the reverse order with the overpotentials of 1118 mV, 827 mV, 637 mV, and 420 mV respectively for unsubstituted, bisubstituted, tetrasubstituted, and octasubstituted [Cu(TPP)]. The observed shifts in the catalytic performance can directly be attributed to increasing charge density on the central metal Cu2+ with the increase in the number of Br groups which in turn has opposite consequences for HER and OER performance.

Halogen Atoms in the Protein-Ligand System. Structural and Thermodynamic Studies of the Binding of Bromobenzotriazoles by the Catalytic Subunit of Human Protein Kinase CK2.

Binding of a family of brominated benzotriazoles to the catalytic subunit of human protein kinase CK2 (hCK2α) was used as a model system to assess the contribution of halogen bonding to protein–ligand interaction. CK2 is a constitutively active pleiotropic serine/threonine protein kinase that belongs to the CMGC group of eukaryotic protein kinases (EPKs). Due to the addiction of some cancer cells, CK2 is an attractive and well-characterized drug target. Halogenated benzotriazoles act as ATP-competitive inhibitors with unexpectedly good selectivity for CK2 over other EPKs. We have characterized the interaction of bromobenzotriazoles with hCK2α by X-ray crystallography, low-volume differential scanning fluorimetry, and isothermal titration calorimetry. Properties of free ligands in solution were additionally characterized by volumetric and RT-HPLC measurements. Thermodynamic data indicate that the affinity increases with bromo substitution, with greater contributions from 5- and 6-substituents than 4- and 7-substituents. Except for 4,7-disubstituted compounds, the bromobenzotriazoles adopt a canonical pose with the triazole close to lysine 68, which precludes halogen bonding. More highly substituted benzotriazoles adopt many additional noncanonical poses, presumably driven by a large hydrophobic contribution to binding. Some noncanonical ligand orientations allow the formation of halogen bonds with the hinge region. Consistent with a predominantly hydrophobic interaction, the isobaric heat capacity decreases upon ligand binding, the more so the higher the substitution.

Methoxy and bromo scans on N-(5-methoxyphenyl) methoxybenzenesulphonamides reveal potent cytotoxic compounds, especially against the human breast adenocarcinoma MCF7 cell line

Thirty seven N-(5-methoxyphenyl)-4-methoxybenzenesulphonamide with methoxy or/and bromo substitutions (series 1-4) and with different substituents on the sulphonamide nitrogen have been synthesised. 21 showed sub-micromolar cytotoxicity against HeLa and HT-29 human tumour cell lines, and were particularly effective against MCF7. The most potent series has 2,5-dimethoxyanilines, especially the 4-brominated compounds 23–25. The active compounds inhibit microtubular protein polymerisation at micromolar concentrations, thus pointing at tubulin as the target. Co-treatment with the MDR inhibitor verapamil suggests that they are not MDR substrates. Compound 25 showed nanomolar antiproliferative potency. It severely disrupts the microtubule network in cells and arrests cells at the G2/M cell-cycle phase, thus confirming tubulin targeting. 25 triggered apoptotic cell death, and induced autophagy. Docking studies suggest binding in a distinct way to the colchicine site. These compounds are promising new antitumor agents acting on tubulin.

Design, Synthesis, and Biological Evaluation of Pyridazinones Containing the (2-Fluorophenyl) Piperazine Moiety as Selective MAO-B Inhibitors.

Twelve pyridazinones (T1–T12) containing the (2-fluorophenyl) piperazine moiety were designed, synthesized, and evaluated for monoamine oxidase (MAO) -A and -B inhibitory activities. T6 was found to be the most potent MAO-B inhibitor with an IC50 value of 0.013 µM, followed by T3 (IC50 = 0.039 µM). Inhibitory potency for MAO-B was more enhanced by meta bromo substitution (T6) than by para bromo substitution (T7). For para substitution, inhibitory potencies for MAO-B were as follows: -Cl (T3) > -N(CH3)2 (T12) > -OCH3 (T9) > Br (T7) > F (T5) > -CH3 (T11) > -H (T1). T6 and T3 efficiently inhibited MAO-A with IC50 values of 1.57 and 4.19 µM and had the highest selectivity indices (SIs) for MAO-B (120.8 and 107.4, respectively). T3 and T6 were found to be reversible and competitive inhibitors of MAO-B with Ki values of 0.014 and 0.0071, respectively. Moreover, T6 was less toxic to healthy fibroblast cells (L929) than T3. Molecular docking simulations with MAO binding sites returned higher docking scores for T6 and T3 with MAO-B than with MAO-A. These results suggest that T3 and T6 are selective, reversible, and competitive inhibitors of MAO-B and should be considered lead candidates for the treatment of neurodegenerative disorders like Alzheimer’s disease.

A REPORT ABOUT BENZOXAZINONE MATERIAL

In this study, the objective was to investigate the Benzoxazinone material using the uncorrected and open capillary method for conducting and reporting the melting points. Laboratory grade and analytical grade reagents were used for conducting the synthesis and analytical studies based on with or without modification appropriately as and were required. Results showed that First of all the Synthesis of 2H-1, 4- benzoxazin-3(4H)-one was carried out by reacting 2- amino phenol with chloro acetyl chloride in dichloromethane in presence of triethylamine and then the bromo substitution was done by reacting with dibromoethane. Piperazine substituents were prepared in laboratory and then the title compounds were synthesized. One additional benzoyl substitution was also done. The entire synthesized compounds were primarily characterized by running T.L.C. and melting point analysis.

In silico fight against novel coronavirus by finding chromone derivatives as inhibitor of coronavirus main proteases enzyme.

Novel coronavirus, 2019-nCoV is a danger to the world and is spreading rapidly. Very little structural information about 2019-nCoV make this situation more difficult for drug designing. Benzylidenechromanones, naturally occurring oxygen heterocyclic compounds, having capability to inhibit various protein and receptors, have been designed here to block mutant variety of coronavirus main protease enzyme (SARC-CoV-2 Mpro) isolated from 2019-nCoV with the assistance of molecular docking, bioinformatics and molecular electrostatic potential. (Z)-3-(4′-chlorobenzylidene)-thiochroman-4-one showed highest binding affinity to the protein. Binding of a compound to this protein actually inhibits the replication and transcription of the virus and, ultimately, stop the virus multiplication. Incorporation of any functional groups to the basic benzylidenechromanones enhances their binding ability. Chloro and bromo substitutions amplify the binding affinity. ADME studies of all these compounds indicate they are lipophilic, high gastro intestine absorbable and blood-brain barrier permeable. The outcome reveals that the investigated benzylidenechromanones can be examined in the case of 2019-nCoV as potent inhibitory drug of SARC-CoV-2 Mpro, for their strong inhibition ability, high reactivity and effective pharmacological properties.Electronic supplementary materialThe online version of this article (10.1007/s11224-020-01537-5) contains supplementary material, which is available to authorized users.

Monocarbonyl Curcumin-Based Molecular Hybrids as Potent Antibacterial Agents.

Keeping in view various pharmacological attributes of curcumin, coumarin, and isatin derivatives, triazole-tethered monocarbonyl curcumin–coumarin and curcumin–isatin molecular hybrids have been synthesized and evaluated for their antibacterial potential against Gram-positive (Enterococcus faecalis and Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) human pathogenic bacterial strains. Among all hybrid molecules, A-4 and B-38 showed the most potent antibacterial activity with inhibition zones of 29 and 31 mm along with MIC values of 12.50 and 6.25 μg/mL, respectively. Structure–activity relationship that emerged from biological data revealed that the two-carbon alkyl chain between triazole and coumarin/isatin moiety is well tolerable for the activity. Bromo substitution at the fifth position of isatin, para-cholo substitution in the case of curcumin–isatin, and para-methoxy in the case of curcumin–coumarin hybrids on ring A of curcumin are most suitable groups for the antibacterial activity. Various types of binding interactions of A-4 and B-38 within the active site of dihydrofolate reductase (DHFR) of S. aureus are also streamlined by molecular modeling studies, suggesting their capability in completely blocking DHFR.

Synthesis and Cytotoxic Studies of Undecenoic Acid-based Schiffs Base Derivatives Bearing 1,2,4-Triazole Moiety

A series of novel 1,2,4-triazole-based schiff’s base derivatives were synthesized by condensing undecenoic triazole compound with various substituted benzaldehydes. Compounds so synthesized were thoroughly characterized using 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, high resolution mass spectrometry and Fourier transform-infrared spectroscopy. Cytotoxicity of these compounds was tested in vitro on three cancer cell lines, B16 F10 (mouse melanoma cancer cells), HCT-15 (human colon cancer cells), SKOV3 (human ovarian cancer cell line) and NIH-3T3 (normal mouse embryonic fibroblasts) using MTT assay. The results showed that most of the compounds exhibited cytotoxicity against the tested cell lines. Among the tested compounds, 6g and 6n showed significant cytotoxicity against B16 F10 cells and compounds 6i, 6n, 6o, 6p and 6q against HCT-15 cell line. The schiff’s base derivative 6g, appeared to be the most effective on B16 F10 cancer cells due to bromo substitution on the 4th position of the phenyl ring. Altogether, the cytotoxicity of these compounds observed against cancer cells indicate anticancer potential.

Synthesis and application of N-butyl substituted phthalimide disperse dyes

Three azo dyes were synthesized using N-butyl substituted phthalimides as diazo components. All of the synthesized intermediate derivatives and dyes were characterized by mass spectrometry, proton nuclear magnetic resonance, infrared (IR) and elemental analyses. Synthesized dyes were also evaluated for their dyeing behavior and fastness properties toward polyester fabric. The ultraviolet-visible absorption maxima of the dyes were observed in the range of 445–563 nm. Bromo and cyano substitutions at the 3- and/or 5- positions of the phthalimide ring resulted in hypsochromic and bathochromic shifts, respectively. IR spectra peaks at 1770 and 1395 cm−1 of hydrolyzed dye showed that C–O groups appeared under relatively mild alkaline conditions. The K/ S values of dyed polyester/elastane fabrics decreased obviously as the pH value increased. Hydrolysis of the phthalimide ring was found to be largely influenced by steric effects rather than inductive effects. Bromo substituted dyes have the lowest rates of hydrolysis. Compared with S-type dyeing disperse dyes, phthalimide dyes have lower dyeing rates and lower levelness of dye migration. The ωB97XD/6-311G(d,p) calculation found that pi-stacking interactions of phthalimide–benzene and phthalimide–phthalimide dimers increased the dye–fiber and dye–dye interactions.

Synthesis of N′-arylidene-2-(5-aryl-1H-1, 2, 4-triazol-3-ylthio) acetohydrazides as antidepressants

A series of N′-arylidene-2-(5-aryl-1H-1, 2, 4-triazol-3-ylthio) acetohydrazide were synthesized. Condensation of aromatic aldehydes with 2-(5-aryl-1H-1, 2, 4-triazol-3-ylthio) acetohydrazide gave corresponding N′ -arylidene-2-(5-aryl-1H-1, 2, 4-triazol-3-ylthio) acetohydrazide. Spectral and elemental analysis was used for structural elucidation of novel 1, 2, 4-triazole schiff bases. The newly synthesized compounds were screened for their antidepressant activity by using tail suspension test in mice. Compound 4l showed significant activity among the series. A series of new N′-arylidene-2-(5-aryl-1H-1, 2, 4-triazol-3-ylthio)acetohydrazide have been synthesized and characterized. The results revealed that compound 4l with bromo substitution exhibited promising antidepressant activity among the series.

Synthesis and Screening of Modified 6,6'-Bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[e][1,2,4]triazin-3-yl)-2,2'-bipyridine Ligands for Actinide and Lanthanide Separation in Nuclear Waste Treatment.

Effects of chloro and bromo substitution at the 4-position of the pyridine ring of 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[e][1,2,4]triazin-3-yl)-2,2'-bipyridine (CyMe4-BTBP) have been studied with regard to the extraction of Am(III) from Eu(III) and Cm(III) from 0.1-3 M HNO3. Similarly to CyMe4-BTBP, a highly efficient (DAm > 10 at 3 M HNO3) and selective (SFAm/Eu > 100 at 3 M HNO3) extraction was observed for Cl-CyMe4-BTBP and Br-CyMe4-BTBP in 1-octanol but in the absence of a phase-transfer agent.

Intramolecular cycloadditions of photogenerated azaxylylenes: an experimental and theoretical study.

The mechanism of intramolecular cycloadditions of azaxylylenes photogenerated via excited-state intramolecular proton transfer (ESIPT) in aromatic o-amido ketones and aldehydes bearing unsaturated functionalities was studied experimentally and computationally. In time-correlated single-photon counting experiments, no relation was found between lifetimes of singlet species and the nature of the amide pendant, either unsaturated furanpropanamide, capable of photocyclization, or the acetamide control. Steady-state emission for amido-tetralone derivatives showed comparable dual emission bands, but bromo substitution decreased the intensity of the ESIPT band. The most reactive derivatives of amidobenzaldehydes were virtually lacking the ESIPT band. The quantum yield of cycloaddition is decreased in the presence of triplet quenchers, O2 or trans-piperylene, and improved with heavy atom substitution in the aromatic ring, providing further evidence for the initial mechanistic hypothesis in which the fast singlet-state ESIPT is accompanied by the ISC in the tautomer (azaxylylene), which undergoes stepwise addition to the tethered unsaturated pendants.

Small molecules with pyridine backbone modified with carbazole, fluorine and bromine for white light-emitting diode applications

Seven compounds with pyridine as the backbone modified by carbazole moiety, bromine atom and fluorine atom were synthesized. Compounds 1, 2, 3 with bromo substitution at the 2-position and carbazole modification at the 5-position of pyridine emit not only a sharp blue singlet fluorescence but also a wide banded excimer-based orange emission. The two colors coming from a single molecule can be used to fabricate a simplified white light emitting device. The electroluminescence based on 1 and 2 exhibits white-light emission with CIE coordinates of x=0.25 and y=0.30 for 1 and x=0.33 and y=0.37 for 2 at high current densities, very close to pure white emission. In addition, the role of bromo-substitution at pyridine is concluded to be essential to generate molecular interaction thus an excimer emission.

In Vitro Evaluation of Guanidine Analogs as Sigma Receptor Ligands for Potential Anti-Stroke Therapeutics

Currently, the only Food and Drug Administration-approved treatment of acute stroke is recombinant tissue plasminogen activator, which must be administered within 6 hours after stroke onset. The pan-selective σ-receptor agonist N,N'-di-o-tolyl-guanidine (o-DTG) has been shown to reduce infarct volume in rats after middle cerebral artery occlusion, even when administered 24 hours after stroke. DTG derivatives were synthesized to develop novel compounds with greater potency than o-DTG. Fluorometric Ca(2+) imaging was used in cultured cortical neurons to screen compounds for their capacity to reduce ischemia- and acidosis-evoked cytosolic Ca(2+) overload, which has been linked to stroke-induced neurodegeneration. In both assays, migration of the methyl moiety produced no significant differences, but removal of the group increased potency of the compound for inhibiting acidosis-induced [Ca(2+)](i) elevations. Chloro and bromo substitution of the methyl moiety in the meta and para positions increased potency by ≤160%, but fluoro substitutions had no effect. The most potent DTG derivative tested was N,N'-di-p-bromo-phenyl-guanidine (p-BrDPhG), which had an IC(50) of 2.2 µM in the ischemia assay, compared with 74.7 μM for o-DTG. Microglial migration assays also showed that p-BrDPhG is more potent than o-DTG in this marker for microglial activation, which is also linked to neuronal injury after stroke. Radioligand binding studies showed that p-BrDPhG is a pan-selective σ ligand. Experiments using the σ-1 receptor-selective antagonist 1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine dihydrochloride (BD-1063) demonstrated that p-BrDPhG blocks Ca(2+) overload via σ-1 receptor activation. The study identified four compounds that may be more effective than o-DTG for the treatment of ischemic stroke at delayed time points.

Novel chalcones and 1,3,5‐triphenyl‐2‐pyrazoline derivatives as antibacterial agents

Novel sixteen chalcones and thirteen 1,3,5-triphenyl-2-pyrazolines were synthesized and characterized using FT-IR, HR-Mass, NMR (¹H-NMR, ¹³C-NMR, 135 DEPT, ¹H-¹H CoSY and ¹H and ¹³C CoSY) and XRD. These compounds were evaluated for their antibacterial activity against six micro-organisms, namely Bacillus subtilis NCIM 2718, Staphylococcus aureus NCIM 5021, Salmonella typhi NCIM 2501, Enterobacter aerogenes NCIM 5139, Pseudomonas aeruginosa NCIM 5029, and Proteus vulgaris NCIM 2813 by twofold dilution method using resazurin as the indicator dye. In the case of chalcones, compounds with hydroxyl and bromo substitutions in the B-ring favor activity and benzyloxy substitution irrespective of its position in the A-ring. In the case of 1,3,5-triphenyl-2-pyrazolines, chloro substitution in the A-ring favors activity. Hydrophilic/lipophilic balance of the compounds plays a major role in their antibacterial activity.

Tuning the Kinetics and Energetics of Diels−Alder Cycloaddition Reactions to Improve Poling Efficiency and Thermal Stability of High-Temperature Cross-Linked Electro-Optic Polymers

A comprehensive theoretical and experimental study of the bromo effect on Diels−Alder (DA) and retro-Diels−Alder (rDA) reactions between the anthracene-containing dienes and maleimide dienophile has been conducted to improve thermal stability and poling efficiency of electro-optic (EO) polymers. Calculations with density functional theory (DFT) reveal that the bromo substitution on anthracene-based dienes leads to significantly increased cycloaddition exothermicities (9−12 kcal/mol) but has a minor effect on their activation barriers (0.6−3 kcal/mol) when reacted with N-phenylmaleimide dienophile. These calculated values correlate very well with the experimental results obtained from a series of model compounds. The DA/rDA cross-linking protocols based on these compounds can be applied to several nonlinear optical (NLO) polymers and result in large EO coefficients (r33) (as high as 69 pm/V) and greatly improved thermal stability (up to 250 °C). This demonstrates that controlled DA/rDA reactions can be use...

Heteroaryl Ethers by Oxidative Palladium Catalysis of Pyridotriazol-1-yloxy Pyrimidines with Arylboronic Acids

The oxidative palladium-catalyzed cross-coupling of pyrimidines containing pyridotriazol-1-yloxy (OPt) as either a urea or an amide functional group with arylboronic acids in the presence of Cs(2)CO(3) in DME containing 0.6-1.0% H(2)O is described for the preparation of heteroaryl ethers. The bromo substitution in the case of 3-(5-bromo-pyrimidin-2-yloxy)-3H-[1,2,3]triazolo[4,5-b]pyridine 1 could serve as a handle for further elaborations such as Suzuki coupling for attaching varied aryl groups.

Cycloaddition Across the Benzofuran Ring as an Approach to the Morphine Alkaloids

The intramolecular Diels-Alder reaction of several amidofurans tethered onto a benzofuran ring was examined as a strategy for the synthesis of morphine. Bromo substitution on the furan ring did not provide sufficient activation to allow the cycloaddition to take place across the aromatic benzofuran. However, the presence of a large o-methylbenzyl group on the amido nitrogen atom causes the reactive s-trans conformation of the amidofuran to be highly populated, thereby facilitating its Diels-Alder cycloaddition across a tethered benzofuran.

Regioselective Synthesis of Antipodal β-Tetrabrominated meso-Tetraarylporphyrins

Abstract A series of meso-tetraarylporphyrins bearing electron-donor or electron-withdrawing substituents at the meso-phenyl groups were examined for antipodal β-pyrrole tetrabromination using different brominating agents. Porphyrins bearing electron-donor substituents undergo bromination at moderate temperatures with N-bromosuccinimide as the brominating agent while the electron-deficient porphyrins require liq. Br2 at room temperature. The brominated porphyrins were isolated in moderate to very good yields. Synthesized compounds were characterized by electronic absorption, 1H NMR, and mass spectroscopic methods. Regioselectivity of an electron-deficient porphyrin, 2,3,12,13-tetrabromo-5,10,15,20-tetrakis(4-methoxycarbonylphenyl)porphyrin was examined by single-crystal X-ray structure analysis and showed antipodal β-pyrrole bromo substitution.