Tài liệu miễn phí Hoá học

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Reduction behavior of fenoxaprop-p-ethyl and its voltammetric determination

The reduction behavior of fenoxaprop-p-ethyl (FNX) was studied on a hanging mercury drop electrode. FNX showed 2 reduction peaks at about –0.7 V and at about –0.9 V versus Ag/AgCl/3.0 M KCl in Britton–Robinson buffer at pH 4.8. Both reductions were irreversible and adsorption was effective. The reduction peaks were assigned to the reduction of C=N to CH–NH and the reduction of C=O to CH–OH. Square-wave voltammetry has been proposed and validated for quantification of FNX in different samples.

4/5/2023 5:18:09 AM +00:00

Synthesis and evaluation of antioxidant activities of novel 1,3,4-oxadiazole and imine containing 1H-benzimidazoles

Some novel 2-(substitutedbenzylthio)-5-((2-(4-substitutedphenyl)-1H -benzo[d]imidazol-1-yl)methyl)-1,3,4- oxadiazoles (5–12) and 2-(2-(4-chlorophenyl)-1H -benzo[d]imidazol-1-yl)-N ′ -(arylmethylene)acetohydrazide derivatives (13–22) were prepared and their in vitro antioxidant properties were investigated by determination of rat liver microsomal NADPH-dependent inhibition of lipid peroxidation (LP) levels and microsomal ethoxyresorufin O-deethylase (EROD) activity. Compound 18 was found to be the most active compound with 100% inhibition on LP level and 92% inhibition on EROD. Compounds 4b, 17, and 19 showed the strongest inhibitory effect (97%) on EROD.

4/5/2023 5:18:02 AM +00:00

Secondary metabolites from Sambucus ebulus

A new nonglycosidic iridoid, sambulin B (1), was isolated from the methanol extract of Sambucus ebulus L. leaves along with a recently reported new nonglycosidic iridoid, 10-O-acetylpatrinoside aglycone (sambulin A) (2); 2 flavonoids, isorhamnetin-3-O-β -D-glucopyranoside (3) and isorhamnetin-3-O-rutinoside (4); and a mixture of 2 flavonoids (5), quercetin-3-O-β -D-glucopyranoside and quercetin-3-O-β -D-galactopyranoside. Their structures were elucidated by 1-D and 2-D nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) experiments.

4/5/2023 5:17:56 AM +00:00

Dual effect of coumarin benzimidazolium ionic salt covalently bonded on a silica network

Synthesis of the ionic liquid 1-allyl-3-(4-methyl-7,8-dihydroxy-2H-chromen-2-one) benzimidazolium chloride followed by the conversion of ammonium salts on the imidazole ring hooked to the coumarin group was modified by postmodification of the silica matrix where 3-chloropropyltrimethoxysilane was used as not only a surface modification agent, but also as an ATRP halogen source. The synergetic effect of charged ammonium groups as well as hydroxyl groups present on the coumarin was investigated in terms of ATRP polymerization. The results confirmed that brush polymers show outstanding antibacterial effects against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.

4/5/2023 5:17:49 AM +00:00

Kinetics and performance studies of a switchable solvent TMG (1,1,3,3-tetramethylguanidine)/1-propanol/carbon dioxide system

The rate constants and the activation energies of the reaction between carbon dioxide and 1,1,3,3-tetramethylguanidine (TMG) in 1-propanol solution were measured by a stopped-flow technique at a temperature range of 288–308 K and at a TMG concentration range of 2.5–10.0 wt %. Based on the pseudo-first-order reaction for CO2 , the reaction was modeled by a termolecular reaction mechanism, which resulted in a rate constant of 199.30 m 3 kmol −1 s −1 at 298 K. The activation energies were 5.19 kJ/mol and 5.26 kJ/mol at 2.5 and 5.0 wt % TMG, respectively. In addition, carbon dioxide absorption capacity was investigated using a gas–liquid contact system.

4/5/2023 5:17:42 AM +00:00

Electrochemical monitoring of the interaction between mitomycin C and DNA at chitosan–carbon nanotube composite modified electrodes

Single-walled carbon nanotube (CNT) and chitosan composite (chitosan*CNT) based sensors were developed as DNA biosensors, and then they were applied for electrochemical investigation of the interaction between the anticancer drug mitomycin C (MC) and DNA. The oxidation signals of MC and guanine were monitored before and after the interaction process by differential pulse voltammetry (DPV). The DPV results were in good agreement with those of electrochemical impedance spectroscopy (EIS). Analytical parameters such as DNA concentration, MC concentration, and MC interaction time with DNA were optimized. The detection limits were 6.85 µg/mL for DNA and 11.01 µg/mL for MC.

4/5/2023 5:17:32 AM +00:00

Water-soluble phthalocyanines containing azo dye; microwave-assisted synthesis and photochemical properties of ZnPcs

Novel water-soluble metallophthalocyanines (M: Co, Ni, Cu, Zn) containing azo dye were characterized. The structures were confirmed by IR, UV/vis, 1H NMR, 13C NMR, mass spectroscopy, and elemental analysis. Photochemical properties and aggregation behavior of zinc phthalocyanines were investigated. Singlet oxygen quantum yields of the zinc phthalocyanines (2d, 3d, 5d, and 6d) were 0.8, 0.57, 0.71, and 0.46, respectively.

4/5/2023 5:17:26 AM +00:00

Microwave-assisted synthesis of novel nonperipherally substituted metallophthalocyanines bearing (7-(trifluoromethyl)quinolin-4-yl)oxy groups

The synthesis, characterization, and spectroscopic properties of novel nonperipherally tetrasubstituted metallophthalocyanines (zinc, cobalt, copper, manganese, and indium) bearing 4 (7-(trifluoromethyl)quinolin-4-yl)oxy units has been reported. The new compounds have been characterized using UV-Vis, IR, 1H NMR, 13C NMR, 19F NMR, and mass spectroscopic data. The absorption properties of these new complexes were compared to those of peripherally substituted phthalocyanine derivatives.

4/5/2023 5:17:19 AM +00:00

Microwave-assisted synthesis and characterization of Co(II) phthalocyanine and investigation of its catalytic activity on 4-nitrophenol oxidation

In this study, new cobalt phthalocyanine containing a 2-(2-benzothiazolylthio)ethoxy group at peripheral positions has been synthesized and characterized by spectroscopic methods (IR, UV-Vis elemental analysis, and mass spectroscopies). Catalytic activity of Co(II) phthalocyanine has been investigated in the presence of oxidants such as tert-buthylhydroperoxide, m-chloroperoxybenzoic acid, and H2 O2 . Co(II) phthalocyanine shows catalytically activity and product conversion under mild conditions.

4/5/2023 5:17:13 AM +00:00

New soluble amidoamine substituted phthalocyanines: synthesis, characterization, and investigation of their solution properties

The synthesis of tetraaminopropylamid substituted phthalocyanines was targeted to prepare enhanced soluble phthalocyanines in common solvents from hydrophobic to hydrophilic that bore nonionic groups on their periphery. Metal-free (H2Pc) and metallophthalocyanines (Zn(II) (ZnPc), Cu(II) (CuPc) and Co(II) (CoPc)) were prepared and characterized by UV-Vis, FT-IR, and mass spectroscopies. The 1 H NMR spectra were recorded for the diamagnetic phthalocyanine species H2Pc and ZnPc. The phthalocyanines showed sufficient solubility in common organic solvents such as dimethyl sulfoxide, tetrahydrofuran, and ethanol.

4/5/2023 5:17:02 AM +00:00

Synthesis and properties of novel polymeric metal-free and metallophthalocyanines containing peripherally long 1,2-bis[(3-oxapropyl)oxa]benzene derivatives

New polymeric phthalocyanine moieties (M = 2H, Zn, Ni, Cu, and Co) were synthesized via polytetracyclomerization reaction of o-bis[3-(3,4-dicyanophenoxy)propyloxy]benzene (3), which can be obtained by the reaction of 4-nitrophthalonitrile with o-bis[(3-hydroxypropyl)oxy]benzene. Aggregation and disaggregation behavior of the polymeric phthalocyanine (5) was studied with some alkali and earth alkali metal cations. Measured intrinsic viscosities of the polymeric phthalocyanines exhibited a substantial decreasing tendency with dilution of the solution.

4/5/2023 5:16:55 AM +00:00

Synthesis and spectral and thermal characterization of new metal-free and metallophthalocyanines: investigation of their photophysical, photochemical, and thin film properties

The thermal stabilities of the phthalocyanine compounds were determined by thermogravimetric analysis. For metal-free (2) and zinc (3) phthalocyanines, photochemical (photodegradation and singlet oxygen quantum yields) and photophysical (fluorescence quantum yields and fluorescence lifetimes) properties were analyzed in dimethylsulfoxide (DMSO). The cobalt (4) and copper (5) phthalocyanines were not evaluated for this purpose because of their paramagnetic behavior. The metal-free (2) and zinc (3) phthalocyanines’ fluorescence quenching behaviors were also investigated.

4/5/2023 5:16:46 AM +00:00

Synthesis, characterization, and photophysical and photochemical properties of 3-(4-phenyloxy)coumarin containing metallo- and metal-free phthalocyanines

The synthesis of novel zinc, cobalt, indium, and metal-free phthalocyanines carrying four 3-(4-phenyloxy)coumarins in the periphery/nonperiphery were prepared by cyclotetramerization of 3-[4-(3,4-dicyanophenyloxy)phenyl]coumarin (2)/3-[4-(2,3- dicyanophenyloxy)phenyl]coumarin (3). The novel chromogenic compounds were characterized by elemental analysis, 1 H NMR, mass spectra, F-IR, and UV-vis spectral data. The effects of the coumarin units on the zinc, indium, and metal-free phthalocyanine complexes (2a/3a, 2c/3c, 2d/3d) were also investigated.

4/5/2023 5:16:40 AM +00:00

Synthesis and characterization of novel 2-{[2-(dimethylamino)ethyl](methyl)amino} ethoxy-substituted metallophthalocyanines

The synthesis of novel, symmetrical, tetrasubstituted metallophthalocyanines (cobalt, zinc, and copper) bearing four 2-{[2-(dimethylamino)ethyl](methyl)amino} ethoxy units was reported. The dinitrile derivative was converted into the water-soluble quaternized product by its reaction with methyl iodide. The quaternized zinc phthalocyanine was obtained from the reaction of the water-soluble dinitrile derivative with zinc acetate. The structures of the newly synthesized molecules were proposed according to elemental analysis, 1 H NMR, FT-IR, and UV-Vis spectral data.

4/5/2023 5:16:33 AM +00:00

Diphenylethoxy-substituted metal-free and metallophthalocyanines as potential photosensitizer for photodynamic therapy: synthesis and photophysical and photochemical properties

The synthesis of a 4-(2,2-diphenylethoxy)phthalonitrile (1) and its organosoluble free base (2), zinc(II) (3), nickel(II) (4), and cobalt(II) (5) phthalocyanine derivatives is presented in this work. The novel complexes were characterized by elemental analyses and spectral data such as infrared, nuclear magnetic resonance, ultraviolet visible, and mass data. General tendencies were described for photophysics (fluorescence) and photochemistry (photodegradation and singlet oxygen quantum yields) of the free base and zinc(II) phthalocyanine derivatives in dimethylformamide.

4/5/2023 5:16:27 AM +00:00

Novel metal-free and metallophthalocyanines containing four 21-membered pentathiadiaza macrocycles: synthesis, characterization, and study of aggregation properties

Metal-free phthalocyanine 3 and its metallophthalocyanine derivatives 4, 5, and 6 (M = Zn, Co, and Ni) substituted with four 21-membered pentathiadiaza macrocycles were synthesized and their structures identified by elemental analysis, IR, 1 H NMR, mass, and UV-Vis spectroscopy techniques. The aggregation properties of phthalocyanines 4, 5, and 6 were investigated in different solvents and at different concentrations of dimethylformamide.

4/5/2023 5:16:20 AM +00:00

Synthesis and electrochemical and spectroelectrochemical characterization of chloromanganese(III) phthalocyanines

The synthesis of novel, symmetrical, tetrasubstituted manganese phthalocyanine complexes bearing 4 hexylthio, 2’,3’,4’,5’,6’-pentafluorobenzyloxy, 2’,3’,5’,6’-tetrafluoro-4’-hexylthio-benzyloxy, and 2’,3’,5’,6’-tetrafluoro-4’- pentoxy-benzyloxy units is reported. The new compounds have been characterized by using elemental analyses and UV-Vis, FT-IR, and mass spectroscopic data. The electrochemical properties of the manganese phthalocyanine complexes were investigated by cyclic and square wave voltammetry and the nature of the observed redox processes was studied by spectroelectrochemistry.

4/5/2023 5:16:14 AM +00:00

Synthesis and characterization of tetra-substituted titanium(IV) phthalocyanines with axial ligand

:In this paper, the synthesis and characterization of peripheral tetra-2-(2-ethyloxyethyloxy)ethyloxy substituted oxo-titanium phthalocyanines (TiOPcs) are reported. The reaction of 2,2,3,3-tetrafluoropropoxy substituted and [2-(2- ethoxyethoxy)ethoxy] substituted TiOPcs (1 and 3) with 4-[(6-hydroxyhexyl)oxy]benzene-1,2-diol as a strongly chelating oxygen donor ligand is described. Compounds 1a and 3a bearing the hydroxyl group as an axial ligand of the bulky group are converted into a thiol group (1c and 3c).

4/5/2023 5:16:07 AM +00:00

Nature of second-order nonlinear optical response in phthalocyanine derivatives: a density functional theory study

Density functional theory was employed to investigate a series of phthalocyanine derivatives, discovering the limitation when the expansion of the conjugated system was employed to improve the hyper-Rayleigh scattering response coefficient. Furthermore, an unusually C∞v -type octupolar population was found by electrostatic potential analysis. In addition, the dynamic and static hyper-Rayleigh scattering responses (βHRS) were simulated using the coupled perturbed density functional theory, showing an increasing dynamic βHRS value along with an increase in incident light energy.

4/5/2023 5:15:57 AM +00:00

Coupling ferrocene to brominated tetraazaporphyrin: exploring an alternative synthetic pathway for preparation of ferrocene-containing tetraazaporphyrins

Direct coupling between ferrocenelithium and 3(2),8(7)-dibromo-2(3),7(8),12(13),17(18)-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin resulted in a debromination reaction accompanied by very minor dimerization of the tetraazaporphyrin core, which was explained based on the steric properties of the parent tetraazaporphyrin. The target compounds were characterized using APCI mass spectrometry, UV-vis, and MCD spectroscopy, while the electronic structure of ferrocenylethyl-containing products was predicted by DFT approach. X-ray structures of individual positional isomers of copper 2-bromo-3,7,12,18-tetra-tertbutyl-5,10,15,20-tetraazaporphyrin and 3, 7, 12,18-tetrabromo-2,8,13,17-tetra-tert-butyl-5,10,15,20-tetraazaporphyrin were also discussed.

4/5/2023 5:15:44 AM +00:00

TD-DFT calculations and MCD spectroscopy of porphyrin and phthalocyanine analogues: rational design of photosensitizers for PDT and NIR region sensor applications

Geometry optimizations and TD-DFT calculations have been carried out on series of fused-ring-expanded phthalonitriles, phthalocyanines, and aza-dipyrromethene boron difluoride (aza-BODIPY) dyes and trends in their optical and redox properties have been analyzed. The potential utility of fused-ring-expanded phthalocyanine and aza-BODIPY analogues for photodynamic therapy and near infrared region sensor applications is assessed on this basis. Recent attempts to prepare fused-ring-expanded aza-BODIPY analogues with benzene, pyrazine, and naphthalene rings have demonstrated that the properties of aza-BODIPYs vary markedly when different fused ring systems are added to the β -carbons of the pyrrole rings.

4/5/2023 5:15:35 AM +00:00

Encapsulation of phthalocyanine-C60 fullerene conjugates into metallosupramolecular subphthalocyanine capsules: a turn of the screw

In this communication, encapsulation studies between metallosupramolecular capsule 1, formed by 2 subphthalocyanines (SubPcs) coordinated to 3 metallic centers, and phthalocyanine (Pc)-C60 fullerene conjugates 2–5 have been carried out. It was shown that the encapsulation of the C60 moiety by the SubPc cage occurred exclusively for dyads 2–4, whereas it was not observed in the case of triad 5. The rigidity of the linker between the Pc and the fullerene unit proved to have an important impact in the complex formation.

4/5/2023 5:15:29 AM +00:00

Electrochemistry of Fe(IV) and Mn(IV) corroles containing meso-dichlorophenyl substituents and the use of these compounds as catalysts for the electroreduction of dioxygen in acid media

Two meso-dichlorophenyl substituted metallocorroles were synthesized and characterized as to their electrochemical and spectroelectrochemical properties in dichloromethane, benzonitrile, and pyridine containing 0.1 M tetra-n-butylammonium perchlorate (TBAP) as supporting electrolyte. The examined compounds are represented as (Cl2Ph)3 CorFeIVCl and (Cl2Ph)3 CorMnIVCl where (Cl2Ph)3 Cor is the trianion of 5,10,15-tri(2,4-dichlorophenyl)corrole. Each metallocorrole was examined as to its catalytic activity for the electoreduction of dioxygen when coated on an edge-plane pyrolytic graphite electrode in 1.0 M HClO4.

4/5/2023 5:15:22 AM +00:00

Effect of the anchoring group in porphyrin sensitizers: phosphonate versus carboxylate linkages

Porphyrins are an important family of organic chromophores that have attracted attention as photosensitizers in TiO2 -based dye-sensitized solar cells (DSSCs). This brief review is dedicated to comparative studies of phosphonic and carboxylic acid anchoring groups for attachment of porphyrin sensitizers on semiconductors or conductors surface. Here we have selected some representative examples of recently described phosphonate/carboxylate porphyrins with the aim to demonstrate that porphyrin phosphonate should be a promising anchoring group for such systems.

4/5/2023 5:15:15 AM +00:00

Boron-containing tetrapyrroles

The recent advances in the synthesis of carborane and boronic ester-substituted tetrapyrroles (porphyrins, porphyrazines, and phthalocyanines) are reviewed together with their possible utilization as agents for photodynamic therapy (PDT) and boron neutron capture therapy of cancer (BNCT) as well as dual PDT/BNCT sensitizers.

4/5/2023 5:15:04 AM +00:00

N -bridged dimers of tetrapyrroles complexed by transition metals: syntheses, characterization methods, and uses as oxidation catalysts

N -bridged dimers of tetrapyrroles complexed by transition metals have been known for nearly four decades, and gained renewed attention when their powerful oxidation properties were recently evidenced. This article is a state of the art review of the reported complexes and of their synthetic methods. Beyond classical chemistry characterization tools, specific methods appropriate to their structure are used and are presented in detail. Finally, their uses and importance of oxidation catalysts are reviewed.

4/5/2023 5:14:48 AM +00:00

History, development, and a new concept of phthalocyanines in Turkey

This paper reviews the history of phthalocyanines in Turkey. Phthalocyanines are chemical compounds that were accidently discovered nearly a century ago. The relevant research and articles have grown dramatically in Turkey since our first paper on them containing four [15]crown[5] published in 1986. The ball-type phthalocyanines were produced and published as a new concept in phthalocyanine chemistry for the first time by our group in Turkey in 2006. Unfortunately, with the exception of our work on this subject, almost no papers have been published in Turkey or in other countries since then.

4/5/2023 5:14:41 AM +00:00

Rosmarinic acid: a potent carbonic anhydrase isoenzymes inhibitor

Rosmarinic acid is a water-soluble ester of caffeic acid and 3,4-dihydroxyphenyllactic acids, and is mainly found in plant species including Boraginaceae and Lamiaceae. In this research, we determined the inhibition property of rosmarinic acid on carbonic anhydrase isoenzymes I and II (hCA I and II) purified from human erythrocytes by using Sepharose-4B affinity column chromatography. hCA I and II isoenzymes were obtained with a yield of 57.9% and 67.2% and 76.5- and 509.3-fold purification of each isoenzyme, respectively.

4/5/2023 5:14:34 AM +00:00

Synthesis of tertiary propargylic phosphonates by addition of trialkynylaluminum reagents to acyl phosphonates and investigation of their antimicrobial activities

A series of propargylic alcohols containing phosphonates was synthesized by addition reactions of tris- (propynyl) and tris-(phenylethynyl)aluminum reagents to acyl phosphonates in good yields. Aromatic moieties of the acyl phosphonates with electron-withdrawing groups generally resulted in better isolated chemical yield. Selected propargylic phosphonates were tested for antimicrobial activities. Compounds 3a and 3h showed noticeable antifungal activity, especially against molds.

4/5/2023 5:14:27 AM +00:00

Convenient method for synthesis of various fused heterocycles via utility of 4-acetyl-5-methyl-1-phenyl-pyrazole as precursor

A new, less expensive, solvent-free procedure was developed for the synthesis of some new derivatives of various fused heterocyclic ring systems, namely azolopyridazine, azolotriazine, azinotriazine, thienopyridine, and pyrazolopyridine. The structures of the products prepared were established by their spectral data and elemental analyses. Eight compounds were evaluated for their in vitro antimicrobial activity. Some of the tested compounds exhibited moderate to significant antibacterial and antifungal activities.

4/5/2023 5:14:20 AM +00:00