Presence Of Zinc Chloride Research Articles

Electrooxidative Thiocyanation of Hydroxy‐ and Alkoxybenzenes

We developed an original method for thiocyanation of hydroxy‐ and alkoxy‐substituted benzenes (including naturally occurring compounds) using electrogenerated thiocyanogen, (SCN)₂. The presence of zinc chloride as a Lewis acid significantly enhances reaction efficiency by activating thiocyanogen. Cyclic voltammetry of the reactants and their combinations was employed to optimize reaction conditions and investigate the proposed mechanisms. This method demonstrated broad synthetic utility, leading to mono‐ and bis‐thiocyanated arenes and various heterocycles with yields 36–97%. Notable products include the neuroprotective drug riluzole and precursors for the antiprotozoal drugs toltrazuril and ponazuril.

Synthesis and Biological Evaluation of 3-(2-Benzoyl-4-chlorophenyl)-4H-spiro [indole-3,2-[1,3]thiazolidine]-2,4(1H)- dione Derivatives for Anti-tubercular and Antimicrobial Activities

Objectives: To synthesize a new scaff fold of 3'-(2-Benzoyl-4-chlorophenyl)-4'H-spiro [indole-3,2'-[1,3] thiazolidine]-2,4'(1H)-dione derivatives and to assess the compounds for anti-tubercular and antimicrobial activities. Methods : A new series of 3'-(2-Benzoyl-4-chlorophenyl)-4'H-spiro [indole-3,2'- [1,3] thiazolidine]-2,4'(1H)-dione derivatives were prepared by synthesizing schiff’s bases followed by condensing schiff base with 2-mercaptopropanoic acid in the presence of zinc chloride. Synthesized compounds were characterized by IR, NMR and Mass spectral data. Their antimicrobial, antitubercular and also docking simulations were evaluated. Findings : Compound 3c (floro substituent) showed potent activity against Mycobacterium tuberculosis H37Rv with MIC value of 3.125 µg/ml when compared with standard Isoniazid. Compound 3c, 3d and 3f displayed better antimicrobial activity against used bacterial and fungal species with MIC range of 3-20µg/ml comparable to standard drugs ciprofloxacin and ketoconazole respectively. In silico studies revealed that compound 3c, 3f and 3d had a better binding affinity with M. tuberculosis enoyl-CoA hydratase EchA6 with ΔG values of -9.6kcal/mol, -9.4kcal/mol, and -8.6kcal/mol respectively comparable to isoniazid of -5.4kcal/mol. Compound 3c, 3f and 3d also displayed good binding affinity with DNA gyrase and lanosterol methylase. Novelty : Introducing benzoyl moiety to the thiazolidine ring potentiates the antitubercular and antimicrobial activity of spiro indole derivatives. Keywords: AntiTB, Antimicrobial, Molecular Docking, Spiro indole, Thiazolidine

Synthesis of sustainable mesoporous sulfur-doped biobased carbon with superior performance sodium diclofenac removal: Kinetic, equilibrium, thermodynamic and mechanism

Over the last years, the strategy of employing inevitable organic waste and residue streams to produce valuable and greener materials for a wide range of applications has been proven an efficient and suitable approach. In this research, sulfur-doped porous biochar was produced through a single-step pyrolysis of birch waste tree in the presence of zinc chloride as chemical activator. The sulfur doping process led to a remarkable impact on the biochar structure. Moreover, it was shown that sulfur doping also had an important impact on sodium diclofenac (S-DCF) removal from aqueous solutions due to the introduction of S-functionalities on biochar surface. The adsorption experiments suggested that General and Liu models offered the best fit for the kinetic and equilibrium studies, respectively. The results showed that the kinetic was faster for the S-doped biochar while the maximum adsorption capacity values at 318 K were 564 mg g−1 (non-doped) and 693 mg g−1 (S-doped); highlighting the better affinity of S-doped biochar for the S-DCF molecule compared to non-doped biochar. The thermodynamic parameters (ΔH0, ΔS0, ΔG0) suggested that the S-DCF removal on both adsorbents was spontaneous, favourable, and endothermic.

Access to High-Purity 7m G-cap RNA in Substantial Quantities by a Convenient All-Chemical Solid-Phase Method.

Given the importance of mRNA with 5'-cap, easy access to RNA substrates with different 7m G caps, of high quality and in large quantities is essential to elucidate the roles of RNA and the regulation of underlying processes. In addition to existing synthetic routes to 5'-cap RNA based on enzymatic, chemical or chemo-enzymatic methods, we present here an all-chemical method for synthetic RNA capping. The novelty of this study lies in the fact that the capping reaction is performed on solid-support after automated RNA assembly using commercial 2'-O-propionyloxymethyl ribonucleoside phosphoramidites, which enable final RNA deprotection under mild conditions while preserving both 7m G-cap and RNA integrity. The capping reaction is efficiently carried out between a 5'-phosphoroimidazolide RNA anchored on the support and 7m GDP in DMF in the presence of zinc chloride. Substantial amounts of 7m G-cap RNA (from 1 to 28 nucleotides in length and of any sequence with or without internal methylations) containing various cap structures (7m GpppA, 7m GpppAm , 7m Gpppm6 A, 7m Gpppm6 Am , 7m GpppG, 7m GpppGm ) were obtained with high purity after IEX-HPLC purification. This capping method using solid-phase chemistry is convenient to perform and provides access to valuable RNA substrates as useful research tools to unravel specific issues regarding cap-related processes.

Reaction of Bacterial Poly-3-Hydroxybutyrate with Thionyl Chloride in the Presence of Zinc Chloride, and the Preparation of Chlorine-Containing Oligomers

The degradation patterns of bacterial poly-3-hydroxybutyrate (PHB) in chloroform solution under the action of thionyl chloride in the presence of zinc chloride were studied. When 2.5.mol of zinc chloride and 100 mmol of thionyl chloride were introduced into the solution of 25 mmol PHB, a decrease in the molecular weight of the polymer was observed. During the reaction, a relatively rapid decrease in the molecular weight of the polymer was noted in the first hour of the experiment; thus, the values of the weight-average molecular weight decreased from 840 kDa to 483, 167, 58.6, and 16.7 kDa after 1, 5, 24, and 96 h of the experiment, respectively. The polydispersity also gradually decreased from 2.69 at the beginning to 1.92 at the end of the experiment. Oligomers of PHB containing 3-chlorobutyric acid and 3-hydroxybutyryl chloride residues at the O and C ends of the polymer chain, respectively, were obtained. The results confirm the ability of thionyl chloride to interact with aliphatic esters in the presence of zinc compounds, and demonstrate the possibility of using this reaction to produce oligomeric derivatives of polyesters bearing chloralkyl and acid chloride functional groups.

Narrow Near-Infrared Emission from InP QDs Synthesized with Indium(I) Halides and Aminophosphine.

Nonpyrophoric aminophosphines reacted with indium(III) halides in the presence of zinc chloride have emerged as promising phosphorus precursors in the synthesis of colloidal indium phosphide (InP) quantum dots (QDs). Nonetheless, due to the required P/In ratio of 4:1, it remains challenging to prepare large-sized (>5 nm), near-infrared absorbing/emitting InP QDs using this synthetic scheme. Furthermore, the addition of zinc chloride leads to structural disorder and the formation of shallow trap states inducing spectral broadening. To overcome these limitations, we introduce a synthetic approach relying on the use of indium(I) halide, which acts as both the indium source and reducing agent for aminophosphine. The developed zinc-free, single-injection method gives access to tetrahedral InP QDs with an edge length > 10 nm and narrow size distribution. The first excitonic peak is tunable from 450 to 700 nm by changing the indium halide (InI, InBr, InCl). Kinetic studies using phosphorus NMR reveal the coexistence of two reaction pathways, the reduction of transaminated aminophosphine by In(I) and via redox disproportionation. Etching the surface of the obtained InP QDs at room temperature with in situ-generated hydrofluoric acid (HF) leads to strong photoluminescence (PL) emission with a quantum yield approaching 80%. Alternatively, surface passivation of the InP core QDs was achieved by low-temperature (140 °C) ZnS shelling using the monomolecular precursor zinc diethyldithiocarbamate. The obtained InP/ZnS core/shell QDs that emit in a range of 507-728 nm exhibit a small Stokes shift (110-120 meV) and a narrow PL line width (112 meV at 728 nm).

Crystal Structure of the Metallo-Endoribonuclease YbeY from Staphylococcus aureus.

Endoribonuclease YbeY is specific to the single-stranded RNA of ribosomal RNAs and small RNAs. This enzyme is essential for the maturation and quality control of ribosomal RNA in a wide range of bacteria and for virulence in some pathogenic bacteria. In this study, we determined the crystal structure of YbeY from Staphylococcus aureus at a resolution of 1.9 Å in the presence of zinc chloride. The structure showed a zinc ion at the active site and two molecules of tricarboxylic acid citrate, which were also derived from the crystallization conditions. Our structure showed the zinc ion-bound local environment at the molecular level for the first time. Molecular comparisons were performed between the carboxylic moieties of citrate and the phosphate moiety of the RNA backbone, and a model of YbeY in complex with a single strand of RNA was subsequently constructed. Our findings provide molecular insights into how the YbeY enzyme recognizes single-stranded RNA in bacteria.

Synthesis Docking Studies, Characterization and Anti-tubercular Activity of Ofloxacin Containing Thiazolidinone Derivatives

<p style="text-align: justify;"><strong>Background: </strong>Ofloxacin is a fluoroquinolone antibiotic very useful in the treatment of several bacterial infections. The Thiazolidinone ring system represents a privileged structure in drug discovery. multi-drug-resistant tuberculosis bacteria infects many people worldwide and the disease kills 1.8 million people annually, so a combination of ofloxacin-thiazolidinone gives a great promise for future potential antitubercular drugs. <strong>Methods:</strong> Ofloxacin is treated with hydrazine hydrate results in the form of ofloxacin hydrazides. These hydrazides were treated with various aromatic aldehydes form ofloxacin containing Schiff bases. These compounds are treated with thioglycolic acid in presence of zinc chloride, DMF as solvent forms the ofloxacin containing thiazolidinone derivatives. These derivatives (T1, T2, T3, T4, T5, T6) were purified using Ethanol by recrystallization procedure. Chimera software is used for protein stabilization. The protein 5BS8 was downloaded from PDB. <strong>Results:</strong> these derivatives are characterized by TLC, melting point, solubility and Spectroscopic methods like FT-IR, 1H-NMR and HRMS. Predicted <em>in silico</em> studies using Autodock vina, which is academic free version software and performed antitubercular action of synthesized compounds using standard drugs. The concentrations were prepared (0.8, 1.6, 3.12, 6.25, 12.5, 25, 50, 100 &mu;g/ml) and performed antitubercular Assay using the Microplate Alamar Blue Assay method (MABA method). Docking studies were done using autodock vina free software. <strong>Conclusion:</strong> MIC values reveal that all the synthesized derivatives show the activity in the concentration 1.6 &mu;g/ml compared to standard drugs. the docking studies results that all compounds from T1-T6 showed good binding energies above the standard, the results reveal that these compounds are potent antitubercular agents. <p style="text-align: justify;"><strong>Key words:</strong> Ofloxacin, Thiazolidinone, Antitubercular activity, Docking studies, MABA method, Autodock Vina.

Enhanced Breaking of Lignin and Mesopore Formation in Zinc Chloride Assisted Hydrothermal Carbonization of Waste Biomasses

Hydrochars from hydrothermal carbonization of different biowaste materials (dried dandelion, sawdust, coconut shell powder) formed in the presence of aqueous salt solutions were compared to those obtained by the common method in pure water. Hydrochars with increased carbon contents, pore volume and surface areas were specifically obtained from coconut shell powder in the presence of zinc chloride. Compositional and structural changes within the hydrochar products caused by the process conditions and/or the additive were characterized by solid state 13C NMR spectroscopy, proving that cellulose and, in particular, lignin units in the biomass are more easily attacked in the presence of the salt. Under saline conditions, a distinct particle break-up led to the creation of mesoporosity, as observable from hysteresis loops in nitrogen adsorption isotherms, which were indicative of the presence of pores with diameters of about 3 to 10 nm. The obtained hydrochars were still rich in functional groups which, together with the mesoporosity, indicates the compounds have a high potential for pollutant removal. This was documented by adsorption capacities for the methylene blue and methyl orange dyes, which exceeded the values obtained for other hydrochar-based adsorbers. A subsequent physical activation of the mesoporous hydrochars in steam at different temperatures and times resulted in a further drastic increase in the surface areas, of up to about 750 m2/g; however, this increase is mainly due to micropore formation coupled with a loss of surface functionality. Consequently, the adsorption capacity for the quite large dyes does not provide any further benefit, but the uptake of smaller gas molecules is favored.

Physical and optoelectronic characteristics of novel low-cost synthesized coumarin dye-based metal-free thin films for light sensing applications

Herein, we have evolved a new and efficient procedure for the synthesis of 3-(2-(4-bromophenyl)hydrazone)-2,4-chromandione BPHCvia the cyclization of (4-bromo-phenylhydrazono)-malonic acid with phenol in the presence of zinc chloride. The thermal stability of the final product is investigated by using DSC/TGA techniques. Thermal deposited BPHC thin films are successfully prepared under vacuum. The IR results of BPHC powder and thin films declare that the deposited films exhibit a stable molecular structure even upon annealing. The as-deposited BPHC thin films exhibit a polycrystalline phase and smooth surface, which are enhanced by annealing at 373 K as observed in the XRD and FE-SEM results. The spectrophotometric measurements showed the enhanced optical absorption in UV and visible spectral bands for the annealed films at 373 K with a decreased energy gap of about 2.37 eV. The dispersion behavior is analyzed as a function of annealing temperatures by using a single oscillator model. The BPHC thin films showed strong PL emission at 522 nm with excitonic binding energy ∼0.17 eV. Furthermore, the organic/inorganic hetero-architecture based on BPHC/n-type silicon is designed and fabricated with significant rectification behavior. The microelectronic parameters of the manufactured heterojunction are calculated and discussed in detail. Moreover, the fabricated device showed a promising stable linear response to light signals with responsivity ∼16.9 mA/W and specific detectivity ∼3.35 × 1010Jones. The repeatable, stable, and efficient performance of the present device suggests this material as a powerful candidate for photosensing applications.

Mild bottom-up synthesis of carbon dots with temperature-dependent fluorescence

Bottom-up methods allowing the preparation of carbon dots (CDs) with favorable attributes are highly desirable. Herein, we report the mild bottom-up synthesis of CDs towards temperature sensing. Five kinds of CDs with blue or green fluorescence were synthesized in water or tetrahydrofuran (THF) under moderate conditions (normal pressure, 50~95 °C), with use of carbonyl compounds as carbon sources, such as acetylacetone (AA), cyclohexanone (CH), 2-hydroxy-2-methylpropiophenone (HM), glutaric dialdehyde (GD), and salicylaldehyde (SA). Typically, with use of acetylacetone (AA) as carbon sources, CDs were synthesized at 95 °C in water in the presence of zinc chloride and 1, 2-dichloroethane. The synthesis, characterizations, and optical properties of AA-derived CDs were thoroughly investigated. The resultant CDs exhibit green photoluminescence (PL) at 520 nm with absolute PL quantum yield (QY) of 21%. Moreover, the PL intensity proportionally depends on temperature in the range 150–360 K, which makes AA-derived CDs potentially useful for temperature sensing.

Reaction of 3-(Alkylsulfanylmethyl)pentane-2,4-diones and 4-(Alkylsulfanyl)-3-(alkylsulfanylmethyl)butan-2-ones with Phenylhydrazine in the Presence of Zinc Chloride

Reaction of 3-(Alkylsulfanylmethyl)pentane-2,4-diones and 4-(Alkylsulfanyl)-3-(alkylsulfanylmethyl)butan-2-ones with Phenylhydrazine in the Presence of Zinc Chloride

Synthesis, characterisation, docking studies and anti-microbial evaluation of ethyl (4-substituted phonoxy)-benzodioxophosphol-4-oxothiazolidin-thiophene-2-carboxylates

The reaction of ethyl 3-((3,4-dimethoxybenzylidene)amino) thiophene-2-carboxylate (5) reacts with mercapto acetic acid in presence of zinc chloride in dioxane forms ethyl 3-(2-(3,4-dimethoxyphenyl)-4-oxothiazolidin-3-yl)thiophene-2-carboxamide (6) which on hydrolysis affords the ethyl 3-(3-chloro-2-(3,4-dihydroxyphenyl)-4-oxothiazolidin-3-yl)thiophene-2-carboxylate (7). A new series of ethyl (4-substituted phonoxy)-benzodioxophosphol-4-oxothiazolidin-thiophene-2-carboxylates (9a-g) were synthesized from ethyl 3-(3-chloro-2-(3,4-dihydroxyphenyl)-4-oxothiazolidin-3-yl)thiophene-2-carboxylate (7) by condensing with 4-substituted phenyl phosphoro dichloridates (8a-g). The structures of these analogues (9a-g) have been established by 1H NMR, IR, Mass spectral data and elemental analysis. This study describes the anti-microbial activity and docking studies of newly synthesized analogues (9a-g).

Mechanism study on the formation of furfural during zinc chloride-catalyzed pyrolysis of xylose

Furfural (FF) is a promising platform compound that can be selectively produced by the fast pyrolysis of xylan-based biomass in the presence of zinc chloride (ZnCl2). Whereas, the catalytic effect of ZnCl2 and the FF formation mechanism remain uncovered. The present work aims to give a deep insight into the formation mechanism of FF under the catalysis of ZnCl2 by combining quantum chemistry calculations and fast pyrolysis experiments. Density functional theory (DFT) calculations and fast pyrolysis experiments were conducted with xylose as the model compound. ZnCl2 affects the pyrolysis reactions through the binding of Zn atom and O atom of xylose initially, with manifest electron exchange between Zn and O. The activation free energies of the pyrolysis reactions can be decreased when ZnCl2 stays at the reaction center of the transition states. Both ring-opening and 1,2-dehydration can be promoted by ZnCl2, whereas ring-contraction is hindered by ZnCl2 because ZnCl2 is away from the reaction center of the ring-contraction. Due to the distinct influence of ZnCl2 on different reactions, the rate-determining steps in some of the possible FF formation pathways are changed. Hence, the competitiveness of these pathways is altered to a great degree, which should be responsible for the selective production of FF. Xylose tends to generate FF through the acyclic d-xylose decomposition channel due to the catalysis of ZnCl2. The most favorable FF generation pathway involves the successive cyclization, 1,2-dehydration between 2-OH and 1-H, electrocyclic dehydration, and 1,2-dehydration between 4-OH and 5-H following the formation of a d-xylulose intermediate.

Chemical Synthesis of a Locked Nucleic Acid-Substituted Dinucleotide Cap Analog.

This article describes a reliable and efficient method for synthesis of the dinucleotide cap analog m7(LNA) G[5']ppp[5']G containing a locked nucleic acid moiety. The required LNA intermediate for the final coupling reaction, m7(LNA) GDP, is prepared in six steps starting from 5'-DMTr-N-DMF LNA guanosine. The overall reaction involves removal of DMTr and DMF groups, 5' monophosphorylation, imidazolide formation, diphosphorylation, and regioselective m7 methylation. The final coupling reaction of m7(LNA) GDP with ImGMP in the presence of zinc chloride as a catalyst affords m7(LNA) G[5']ppp[5']G in 59% yield. © 2021 Wiley Periodicals LLC. Basic Protocol: Synthesis of an LNA-substituted dinucleotide cap analog Support Protocol: Preparation of the tris(tributylammonium) phosphate linker.

Ultrastretchable, Tough, Antifreezing, and Conductive Cellulose Hydrogel for Wearable Strain Sensor.

Conductive hydrogels have shown great potential in the field of flexible strain sensors. However, their application is greatly limited due to the low conductivity and poor mechanical properties at subzero temperatures. Herein, an ultrastretchable, tough, antifreezing, and conductive cellulose hydrogel was fabricated by grafting acrylonitrile and acrylamide copolymers onto the cellulose chains in the presence of zinc chloride using ceric ammonium nitrate as the initiator. The resulting hydrogel exhibited ultrastretchability (1730%), excellent tensile strength (160 kPa), high elasticity (90%), good toughness (1074.7 kJ/m3), and fatigue resistance property due to the existence of dipole-dipole and multiple hydrogen-bonding interactions on the hydrogel network. In addition, the introduced zinc chloride endowed the cellulose-based hydrogel with remarkable electric conductivity (1.54 S/m) and excellent antifreezing performance (-33 °C). Finally, the hydrogel showed high sensitivity and stability to monitor human activities. In summary, this work presented a facile strategy to construct conductive hydrogel with excellent antifreezing and mechanical properties simultaneously, which showed great potential for wearable strain sensors.

A facile synthesis of 6-[(4-nitrophenyl)thio]-substituted 2-methylene-2,3-dihydro-1,4-oxazepines from N-propargylic β-enaminones

A one-pot process for the synthesis of 6-[(4-nitrophenyl)thio]-substituted 2-methylene-2,3-dihydro-1,4-oxazepines is reported. When reacted with 4-nitrobenzenesulfenyl chloride, N-propargylic β-enaminones afforded α-sulfenylated N-propargylic β-enaminones, which, in the presence of zinc chloride, underwent electrophilic cyclization to yield 6-[(4-nitrophenyl)thio]-substituted 2-methylene-2,3-dihydro-1,4-oxazepines. Process was found to be general for various N-propargylic β-enaminones along with large substrate scope and high functional group tolerance. This operationally easy method may provide quick access to a library of functionalized 1,4-oxazepines of pharmacological interest.

Selective Functionalization of Benzo‐Fused N‐Heterocycles by Using In Situ Trapping Metalations

AbstractWe have prepared some benzo‐fused N‐heterocycles derivatives by regioselective metalation of quinoline, isoquinoline, quinoxaline, and quinazoline with LiTMP in the presence of zinc chloride. Applying this strategy to synthesize an analog of the antitumor verubulin illustrates its relevance for medicinal chemistry. Computational calculations of the pKa values of the aromatic hydrogens have helped us to rationalize substrate reactivity and metalation regioselectivity by the complex‐induced proximity effect concept.

A simple and affordable kinetic assay of nucleic acids with SYBR Gold gel staining.

Labeling substrates or products are paramount in determining enzymatic kinetic parameters. Several options are available; many laboratories use either radioactive or fluorescent labeling because of their high sensitivity. However, those methods have their own drawbacks such as half-life decay, expensive and hazardous. Here, we propose a novel, simple, economical and fast alternative to substrate labeling for studying the kinetics of nucleic acids: post-migration gel staining with SYBR Gold. Cleavage rates similar to the ones reported in the literature for the I-R3 DNA-cleaving DNA enzyme in the presence of zinc chloride are an indication of the quality of the new method. Moreover, the activity of the hammerhead ribozyme was also monitored by our method to illustrate its versatility. This labeling-free method has several advantages such as its ease of use as well as cost effective and versatility with both non-structured and structured RNAs or DNAs.

Z-Acrylonitrile Derivatives: Improved Synthesis, X-ray Structure, and Interaction with Human Serum Albumin.

In the synthesis of heterocyclic compounds, acrylonitrile derivatives are the most important and appropriate precursors. These compounds are the most important intermediates and subunits for the enhancement of molecules having pharmaceutical or biological interests. Nitrogen-containing compounds have received extensive consideration in the literature over the years. A facile, economic and efficient method has been developed for the synthesis of acrylonitrile derivatives using p-nitrophenylacetonitrile and aromatic/heterocyclic aldehydes in the presence of zinc chloride at room temperature. Spectroscopic data were obtained using the following instruments: Fourier transform infrared spectra (KBr discs, 4000-400 cm-1) by Shimadzu IR-408 Perkin-Elmer 1800 instrument; 1H NMR and 13C NMR spectra by Bruker Avance-II 400 MHz using DMSO-d6 as a solvent containing TMS as the internal standard. To continue our ongoing studies to synthesize heterocyclic and pharmaceutical compounds by mild, facile and efficient protocols, herein we wish to report our experimental results on the synthesis of acrylonitrile derivatives, using various aromatic/heterocyclic aldehydes and p-nitrophenylacetonitrile in the presence of zinc chloride in ethanolic media at room temperature. Some of the new compounds were tested for their human serum albumin activity (HSA) while a study of interaction with HSA protein was performed for compounds 3a and 3b. The results show that compound 3b binds tightly to HSA as compared to compound 3a. It can be concluded that acrylonitrile derivatives can be synthesized by an efficient method via the reaction of p-nitrophenylacetonitrile with aromatic/heterocyclic aldehydes by the use of zinc chloride as an effective solid catalyst. The remarkable features of this procedure include excellent yields (90-95%), short reaction period (30 min.), moderate reaction environment, easy workup procedure and managing of the catalyst. This method may find a wide significance in organic synthesis for the synthesis of the Z-acrylonitrile.