Benzoyl Halides Research Articles

Mitigating bulk halide defects in blue-emissive perovskite nanocrystals using benzoyl halides for efficient light-emitting diodes

While recent advances have demonstrated highly efficient and stable perovskite light-emitting diodes (LEDs), blue perovskite LEDs still show low performance compared to green, red, near IR counterparts. Despite perovskites being well-known for their defect tolerance, blue perovskites are highly vulnerable to defects, which introduce deep trap states. In this study, we mitigated bulk halide vacancies in perovskite nanocrystals (PNCs) via the diffusion-assisted halide repairing strategy. We confirmed halide vacancies inside as-synthesized PNCs, both in the core and on the surface, through HADDF-STEM. By treating PNCs with benzoyl halides, these halide vacancies were further mitigated due to halide diffusion via concentration gradients between the surface and the core, resulting in enhanced PLQY of the PNCs. In the fabrication of blue PNCs LEDs, this approach yielded a comparable efficiency with an EQE of 5.37 % at 469 nm, demonstrating the robustness of our method for efficient blue perovskite LEDs. Furthermore, the peak wavelengths of benzoyl halide-treated PNCs LEDs remained stable during operation, whereas those of pristine PNC LEDs exhibited peak shifts. We believe that our novel approach can be universally applied to various types of perovskites, reducing bulk vacancies. This advancement will be a significant breakthrough for the performance enhancement of blue perovskite LEDs in the future.

SYNTHESIS, ANTIMICROBIAL, AND ANTITUBERCULAR ACTIVITIES OF NOVEL N-PYRAZOLYLBENZAMIDE DERIVATIVES

The current study investigated the antimicrobial and antitubercular activities of novel N-Pyrazolyl Benzamide derivatives. The study includes the synthesis, characterization, and ligand-based molecular docking of the designed molecules. Synthesis of N-Pyrazolyl Benzamide derivatives involves a two-step process in which 5-amino pyrazole (3) intermediate is produced by the condensation reaction of aryl hydrazine (1) and β-keto nitrile (2) in acidic conditions. The final N-Pyrazolyl Benzamide derivatives (5a-n) were synthesized by the reaction involving amide coupling between 5-amino pyrazole (3) and various substituted benzoyl halides (4a-n). The compounds (5a-n) were tested for antimicrobial activity against two gram-negative strains (E. coli and S. Typhi), two gram-positive strains (S. aureus and B. subtilis) and M. tuberculosis MTB H37Rv (ATCC 27294) strains were used for evaluating antitubercular activity. Molecular docking studies of designed derivatives were performed with the Schrodinger glide package against mycobacterial pantothenate synthetase (PDB ID: 4MQ6). All the tested compounds displayed moderate to good antimicrobial and antitubercular activity against the selected strains of bacteria. All the docked molecules were found occupying the active site and established a minimum of two hydrogen bond interactions in molecular docking studies

Benzoyl Halide as Alternative Precursor for Synthesis of Lead Free Double Perovskite Cs₃Bi₂Br9 Nanocrystals.

Ternary bismuth halides are interesting functional materials closely related to Pb halide perovskite photovoltaic material, and are widely sought after due to reduced toxicity of Bi compared to Pb. There are several reports on synthesis of Cs₃Bi₂Br9 nanocrystals (NCs) due to its being relatively stable compared to lead perovskite. Cs₃Bi₂Br9 nanocrystals have been synthesised using benzoyl bromide as an precursor using hot injection process at two different temperatures of 120 °C and 160 °C. Samples have been characterized for its structural, optical, microstructural and luminescent properties using X-ray diffraction, (XRD) UV-Vis spectroscopy, high resolution transmission electron microscopy and photoluminescent spectroscopy. XRD showed formation of Cs₃Bi₂Br9 phase with mono-crystalline structure. UV-Vis showed two types of band gap in the visible region which shows that the material can be used for photovoltaic applications. HRTEM confined the particles to be composed of nanocrystals with ˜5 nm particles in the samples grown at 120 °C and it the particles joined together yield various structures composed of nanoparticles. The time resolved photoluminescence shows average life times of 3.067 ns and 4.761 ns for samples grown at two different temperatures. To the best of our knowledge, this is the first report where benzoyl halide has been used as alternative precursor for the synthesis of lead free double perovskite Cs₃Bi₂Br9 nanocrystals which have many applications.

The Effect of the ortho Nitro Group in the Solvolysis of Benzyl and Benzoyl Halides.

A kinetic study was carried out on the solvolysis of o-nitrobenzyl bromide (o-isomer, 1) and p-nitrobenzyl bromide (p-isomer, 3), and o-nitrobenzoyl chloride (o-isomer, 2) in a wide range of solvents under various temperatures. In all of the solvents without aqueous fluoroalcohol, the reactions of 1 were solvolyzed at a similar rate to those observed for 3, and the reaction rates of 2 were about ten times slower than those of the previously studied p-nitrobenzoyl chloride (p-isomer, 4). For solvolysis in aqueous fluoroalcohol, the reactivity of 2 was kinetically more reactive than 4. The l/m values of the extended Grunwald–Winstein (G–W) equation for solvolysis of 1 and 2 in solvents without fluoroalcohol content are all significantly larger than unity while those in all the fluoroalcohol solvents are less than unity. The role of the ortho-nitro group as an intramolecular nucleophilic assistant (internal nucleophile) in the solvolytic reaction of 1 and 2 was discussed. The results are also compared with those reported earlier for o-carbomethoxybenzyl bromide (5) and o-nitrobenzyl p-toluenesulfonate (7). From the product studies and the activation parameters for solvolyses of 1 and 2 in several organic hydroxylic solvents, mechanistic conclusions are drawn.

Organotellurium Chemistry: Synthesis and Properties of 2-Acylamino- and 2-Arylamino-1,3-benzotellurazoles

Synthetic methods have been developed to prepare novel 1,3-benzotellurazoles carrying acylamino and arylamino moieties in position 2, in order to investigate their propensity to self-assemble to supramolecular structures. The targeted compounds were obtained in yields ranging from 44% to 67%, by reacting bis(2-aminophenyl) ditelluride with acyl- and aryl isothiocyanates, respectively, and subsequent reductive cyclization of the resulting thiourea derivatives. Seven novel 1,3-benzotellurazole derivatives were prepared: 2-benzoylamino-1,3-benzotellurazole, 2-(4-chlorobenzoylamino)-1,3-benzotellurazole, 2-(2-bromobenzoylamino)-1,3-benzotellurazole, 2-(4-bromobenzoylamino)-1,3-benzotellurazole, 2-(4-methoxybenzoylamino)-1,3-benzotellurazole, 2-phenylamino-1,3-benzotellurazole, and 2-(4-chlorophenylamino-1,3-benzotellurazole. A simplified protocol was employed to synthesize all acyl isothiocyanates needed for their preparation from benzoyl halide derivatives and potassium thiocyanate. The reductive cyclization of the intermediate thioureas was challenging, only the use of hydroxymethanesulfinate in the presence of elemental mercury provided synthetically useful product yields. A mechanism was proposed, consisting of the insertion of mercury into the Te-Te bond, followed by intramolecular nucleophilic attack of the thiocarbonyl moiety by the resulting insertion product. All 2-acylamino-1,3-benzotellurazoles are crystalline solids, which are stable to ambient light, air and moderate heat. A characterization of selected samples by X-ray crystallography indicated that they form dimers in solid state, resulting from hydrogen bonding between the exocyclic and endocyclic nitrogen atoms of two adjacent molecules. This sets them apart from 2-alkyl- and 2-aryl-1,3-benzotellurazoles, which are known to self-assemble into supramolecular wires.

Benzoyl Halides as Alternative Precursors for the Colloidal Synthesis of Lead-Based Halide Perovskite Nanocrystals.

We propose here a new colloidal approach for the synthesis of both all-inorganic and hybrid organic–inorganic lead halide perovskite nanocrystals (NCs). The main limitation of the protocols that are currently in use, such as the hot injection and the ligand-assisted reprecipitation routes, is that they employ PbX2 (X = Cl, Br, or I) salts as both lead and halide precursors. This imposes restrictions on being able to precisely tune the amount of reaction species and, consequently, on being able to regulate the composition of the final NCs. In order to overcome this issue, we show here that benzoyl halides can be efficiently used as halide sources to be injected in a solution of metal cations (mainly in the form of metal carboxylates) for the synthesis of APbX3 NCs (in which A = Cs+, CH3NH3+, or CH(NH2)2+). In this way, it is possible to independently tune the amount of both cations and halide precursors in the synthesis. The APbX3 NCs that were prepared with our protocol show excellent optical properties, such as high photoluminescence quantum yields, low amplified spontaneous emission thresholds, and enhanced stability in air. It is noteworthy that CsPbI3 NCs, which crystallize in the cubic α phase, are stable in air for weeks without any postsynthesis treatment. The improved properties of our CsPbX3 perovskite NCs can be ascribed to the formation of lead halide terminated surfaces, in which Cs cations are replaced by alkylammonium ions.

ChemInform Abstract: Palladium‐Catalyzed Coupling of Benzoyl Halides with Aryltrifluorosilanes Leading to Diaryl Ketones.

AbstractThe first Hiyama cross‐coupling of acyl halides or pseudohalides with aryltrifluorosilanes is described.

Palladium-catalyzed Coupling of Benzoyl Halides with Aryltrifluorosilanes Leading to Diaryl Ketones

Acyl–aryl Hiyama coupling of acyl halides with arylsilanes has been achieved by employing a palladium/phosphine catalyst system. A variety of acyl chlorides and fluorides can be applied for coupling with arylsilicon reagents, and unsymmetrical benzophenone derivatives can be prepared using this protocol.

THERMAL ANALYSIS OF EMBELIN SUBSTITUTED BENZOYL HALIDE DERIVATIVES

This paper describes the extraction of embeline from its plant source . The embelin is highly handy in the medical management viz., cytotoxic, antib acterial, wound healing, chemo preventive, lipid lowering agent and many other medical usages. The substituted benzoyl ester derivative of the embelin molecule will also have the medical properties more or less then the parent embelin molecule. They substi tuted derivatives were synthesized by reacting emb elin with different substituted benzoyl h alides in the presence of pyridine as base and dichloro methane as solvent. Amongst them , Fluoro, bromo and Iodo ( halide s) substituted benzoate esters exhibited diffe rent thermal activit ies then its parent embeline molecule . The se substituted benzoyl halides showed different thermal activities . The se properties are varying with respect to the position of halide in the phenyl substituted ring . The thermal prosperities p layed vital role in altering lipid lowering activity of the molecule.

Fe-Catalysed oxidative C–H/N–H coupling between aldehydes and simple amides

A novel oxidative coupling of aldehydes with simple amides, most likely involving a radical process, was achieved through the use of an iron catalyst. Various amides were utilized as substrates to easily construct imides by coupling with aldehydes. A catalytic cycle involving the benzoyl halide intermediate is proposed based on our experimental results.

Rapid and facile synthesis of acyl azides from acyl halides using a polymer-supported azide ion under heterogeneous conditions

In this article a rapid and facile method for synthesis of acyl azide is described. The cross-linked poly(N-methyl-4-vinylpyridinium) azide ion, [P4-VP]N3 is prepared and used as an efficient polymeric reagent for synthesis of acyl azides from acyl halides at room temperature under heterogeneous conditions. Various benzoyl halides, with electron-withdrawing groups as well as electron-donating groups, were transformed into the corresponding benzoyl azides in high to excellent yields in short reaction times. The acyl azide products were characterized by FT-IR, and some of them were also characterized by 1H-and/or 13C-NMR spectroscopy, and physical properties were compared to literature values of known compounds. The spent polymeric reagents can be regenerated and reused for several times without losing their activity. Relative to the reported methods, the present method has the advantages of operational simplicity, mild reaction conditions, fast reaction rates, simple reaction work-up and lower hazardous and potentially explosive nature. Also the present method is the first procedure for the synthesis of acyl azides from acyl halides by using a polymer-supported azide ion under heterogeneous conditions.

Cytotoxicity and radiosensitising activity of synthesized dinitrophenyl derivatives of 5-fluorouracil

Background and the purpose of the studyDual functional agents in which nitroaromatic or nitroheterocyclic compounds are attached through a linker unit to mustards and aziridines have shown higher cytotoxicities than the corresponding counterparts to both aerobic and hypoxic cells and enhanced radiosensitizing activity. In the present investigation cytotoxicity and radiosensitizing activity of 2,4-dinitrobenzyl, 2,4-dinitrobenzoyl, and 2,4-dinitrophenacetyl derivatives of 5-fluorouracil which was assumed to release cytotoxic active quinone methidide and 5-fluorouracil under hypoxic conditions on HT-29 cell line under both aerobic and hypoxic conditions was investigated.Methods5-fluorouracil derivative X-XIII were prepared by the reaction of the corresponding di-nitro substituted benzyl, benzoyl and phenacetyl halides with 5-fluorouracil protected at N-1 with di-t-butoxydicarbonate (BOC) in dimethyl formamide (DMF) in the presence of the potassium carbonate followed by hydrolysis of the blocking group by potassium carbonate in methanol. Cytotoxicity of fluorouracil VIII and tested compounds X-XIII against HT-29 cell line under both aerobic and hypoxic conditions after 48 hrs incubation were measured by determination of the percent of the survival cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and percent of the dead cells using propidium iodide(PI)-digitonine assay and results were used to calculate the corresponding IC50 values. Radiosensitization experiments were carried out by irradiation of the incubations with a 60Co source and clonogenic assay was performed to determine the cell viabilities following treatment with the tested compounds and/or radiation. Sensitization Enhancement Ratio (SER) of each tested compound was obtained from the radiation survival curves in the absence and presence of each sensitizer for 37% survival respectively.Results and major conclusionFindings of the present study showed that alkylation or acylation of 5-fluorouracil result in compounds which have little or no cytotoxicity and radiosensitizing activity under aerobic conditions, but have high cytotoxicity and radiosensitizing effects under hypoxic conditions. Furthermore radiosensitizing activities of compounds under hypoxic conditions increased by increase in their concentrations and SER of the tested 5-FU derivatives at concentrations higher than 50 μmol were equal or higher than 1.6 which is the minimum effective SER of a radiosensitizer in an in vitro assay.

ChemInform Abstract: Kinetics of Aminolysis of Some Benzoyl Fluorides and Benzoic Anhydrides in Non-hydroxylic Solvents

The kinetic form of the spontaneous aminolysis of benzoyl fluorides in non-hydroxylic solvents is unlike that reported for the other benzoyl halides but is similar to that found for the aminolysis of esters. Variations on the mechanisms currently advocated for ester aminolysis are suggested for the benzoyl fluoride reactions. Tetrahedral intermediates are likely, but their rate-determining breakdown to products may involve a simultaneous proton transfer to the leaving fluoride ion. The kinetic behaviour differs from that found for aqueous solutions. The kinetics of the spontaneous aminolysis of benzoic anhydrides by primary amines, and by morpholine, in dioxane solution are first-order in each reagent over a wide amine concentration range, but the aminolysis by imidazoles involves also an important kinetic term second-order in amine. The mechanistic implications are discussed. Again the observations differ from some of those reported for aqueous solutions. For aminolyses of a variety of acylating agents, kinetic observations using non-hydroxylic solvents show that the easier it is for the leaving group to depart, owing to the structure of the acylating agent and/or that of the attacking amine, the less important become paths involving two or more amine molecules, but that such paths are generally more important than they are in hydroxylic solvents.

Promoting Mechanistic Changes: Solvolysis of Benzoyl Halides in Nonionic Microemulsions

Solvolysis of benzoyl halides has been studied in nonionic isooctane/Brij30/water microemulsions. The reaction takes place only at the microemulsion interface due to the low solubility of benzoyl halides. The variation of the properties (water content and hydration water nucleophilic character) of the microemulsion interface as the amount of water in the system decreases favors mechanistic changes in the solvolytic reaction. The true rate and equilibrium constants at the interface were obtained by means of the formalism of the pseudophase. Rate constant values at the interface change as the water content of the microemulsion is modified. The changes are consistent with a shift of mechanism from dissociative toward associative. The predominance of either dissociative or associative mechanism is dependent on the characteristics of the leaving group. The associative character decreases as the salient group of the benzoyl halides improves. Moreover, the associative pathway is strongly favored in the microemulsion system studied.

The solvolysis of benzoyl halides as a chemical probe determining the polarity of the cavity of dimethyl-β-cyclodextrin

The solvolysis of benzoyl halides (BzX) in the presence of dimethyl-β-cyclodextrin (DM-β-CD) was studied. Methylation or hydroxyalkylation of the hydroxyl groups in β-cyclodextrin increases their solubility and the highest possible concentration of DM-β-CD that can be dissolved in water is 0.2 M. The ability to use more readily soluble CDs may allow one to determine the stoichiometry of their complexes and the properties of water held in their cavity with increased precision. Based on the experimental results, this cyclodextrin forms host–guest complexes of variable stoichiometry where two reaction pathways are considered: in water and in the internal cavity of the cyclodextrin. We determined the rate constants for the halides in their reaction inside the internal cavity. This allowed the influence of the substituent and leaving group on the reactions in the bulk water and the internal cavity of DM-β-CD to be compared. Depending on whether the solvolysis reaction is preferentially associative or dissociative, the presence of the cyclodextrin has a catalytic or inhibitory effect, respectively.

Solvolysis of Benzoyl Halides in Water/NH4DEHP/Isooctane Microemulsions

A study was carried out on the solvolysis reactions of different benzoyl halides in microemulsions of water/NH4DEHP/isooctane, where NH4DEHP is ammonium bis(2-ethylhexyl) phosphate. Because of the low solubility of benzoyl halides in water, they are distributed between the continuous medium and the interface of the microemulsion, where the reaction takes place. The application of the pseudophase model has allowed us to obtain the distribution constants and the rate constants at the interface for the benzoyl halides. Reaction mechanisms and the changes in these mechanisms in terms of the water content of the microemulsion have been determined on the basis of kinetic data. The influence of the substituent and the leaving group on the reaction rate has been investigated. A comparison of kinetic results with those previously obtained in water/AOT/isooctane microemulsions allows a kinetic evaluation of the change in the microemulsion properties with the surfactant.

CsF‐Celite, an Efficient Solid State Reagent for the Syntheses of Thioesters and Thioethers.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Reaction rates in ultrasonic emulsions of dense carbon dioxide and water

AbstractPower ultrasound provides a surfactant‐free means of emulsifying dense near‐critical carbon dioxide and water. Droplet size distributions and volume fractions of the dispersed phases have been measured for acoustically formed emulsions. Hydrolysis rates were measured for a series of 7 benzoyl halides under both silent, phase‐separated conditions and for sonicated, emulsified conditions (30°C, 80 bar, 0.6 W/cm3, 20 kHz). Sonication always accelerated the overall hydrolysis rate, sometimes by as much as 200‐fold. Two physical models were developed to describe global kinetics: one for silent and one for sonicated conditions. The model for silent conditions agreed well with the available data set and suggested conditions under which reaction in the carbon dioxide phase (rather than the water phase) might become important. The model for sonicated conditions properly captured the trends in the data set and predicted the experimental results to within a factor of 2 in the worst case. Our analysis strongly suggests that ultrasound accelerates phase‐transfer reactions by increasing the water/carbon dioxide interfacial area. © 2005 American Institute of Chemical Engineers AIChE J, 2006

Employment of Palladium Pincer-Complexes in Phenylselenylation of Organohalides

[Reaction: see text]. Palladium pincer-complex-catalyzed selenylation of propargyl-, allyl-, benzyl-, and benzoyl halides could be achieved under mild reaction conditions employing trimethylstannylphenylselenide as selenylating agent. This reaction has a high functional group tolerance as carbmethoxy, tosylamino, nitro, aryl bromide, and unprotected hydroxy groups are tolerated. Mechanistic studies indicate that the catalytic cycle is initiated by formation of a selenium-coordinated palladium pincer-complex, which subsequently reacts with the electrophilic substrate. DFT calculations were performed to explore the mechanism of the transfer of the organoselenium group from palladium to the substrate. These modeling studies revealed some interesting differences between the mechanism of the organoselenium group transfer and (the previously published) organostannane transfer reactions.

Cesium Fluoride—Celite: A Solid Base for Efficient Syntheses of Aromatic Esters and Ethers.

Coupling reactions of a number of aromatic and heteroaromatic phenols with alkyl, acyl or benzoyl halides in acetonitrile with cesium fluoride-Celite are described, demonstrating that this reagent provides an efficient, convenient and practical method for the syntheses of aromatic esters and ethers.