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A new pyrazole-tethered thiazolidine-2,4-dione derivative (8) has been synthesized by the Knoevenagel condensation of 3-(4-nitrophenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (4) and 3-(2,4-dioxothiazolidin-3-yl)propanenitrile (7). The structure of the final compound was confirmed by standard spectroscopic techniques including IR spectroscopy, 1H-NMR spectroscopy, and ESI-MS mass spectrometry. Molecular features including frontier molecular orbital (HOMO-LUMO) energies, reactivity descriptors and molecular electrostatic potential (ESP) of the title molecule were determined using density functional theory (DFT) calculation. The in vitro cytotoxicity of both the intermediate (4) and final (8) compounds were investigated against cancerous (SW-480 and MCF-7) and normal (HEK-293) cell lines by MTT assay. Compound (8) displayed higher activity than (4) with higher sensitivity against breast cancer cell line and lesser toxicity. The experimental data were further complemented by docking and absorption, distribution, metabolism, and excretion (ADME) studies. Communicated by Ramaswamy H. Sarma

In this work, we report synthesis, characterization and corrosion inhibition properties of cationic thiol surfactant-capped silver (SC-Ag-NPs) and gold (SC-Au-NPs) nanoparticles. SC-Ag-NPs and SC-Au-NPs were characterized using regular techniques include TEM. Corrosion study was carried out using carbon steel (CS) in 3.5% NaCl aqueous solution and characterized using multiple electrochemical techniques. Our results suggest that the paint containing SC-Ag-NPs and SC-Au-NPs endow efficient corrosion protection to the CS. Especially, SC-Au-NPs based paint form a stronger barrier between the metal and the corrosive ions, leading to better inhibition properties.

A new metalloporphyrin (4,4′-bipyridine)meso-tetrakis(2,4,6-trimethylphenyl) porphyrinato) zinc(II) ([Zn(TMP)(4,4′-bpy)]) (3) was obtained by reacting meso-tetrakis(2,4,6-trimethylphenyl)porphyrinato) zinc(II) [Zn(TMP)] (2) and 4,4′-bipyridine (4,4′-bpy). The starting material meso-tetrakis(2,4,6-trimethylphenyl)porphyrine (H2TMP, 1) as well as complexes (2 and 3) were characterized by the means of microanalysis, 1H NMR, and ESI-MS techniques. The molecular structure of the final complex (3) was also confirmed by single crystal X-ray crystallography. Detailed photo-physical and electrochemical properties of the complexes were also determined. The oxidative degradation ability of complexes (2 and 3) was evaluated and compared against an organic dye (calmagite). When used as catalyst, complex (2) showed better efficiency ~ 48% than the complex (3) (41%). Overall, this work not only explores the ability of metalloporphyrin to degrade organic dyes in aqueous solution, but also showed that the degradation ability of a metalloporphyrin complex can be fine-tuned by varying axial ligand.

Though challenging, conversion of carbon dioxide (CO2) to valuable products is an emerging area of research. Electrochemical reduction (ECR) has emerged as an efficient and rapid technique to achieve this goal. Herein, 5,10,15,20-tetraphenyl-21H, 23H-porphine manganese(III) chloride [(Mn(TPP)Cl)] catalyzed CO2 reduction at vitreous carbon electrode in acetonitrile electrolyte is reported. The effect of catalyst concentration, addition of Brönsted acid (CF3CH2OH) to CO2-saturated solution have been studied and reported. Based on the results, possible mechanistic pathways have also been suggested and discussed. This work is licensed under a Creative Commons Attribution 4.0 International License.

Introduction: The plastic soft drink bottle from polyethylene terephthalate (PET) was introduced to consumers in 1970s. Because PET have ester group its chemical recycling is preferred. To control and reducethe environmental pollution recycling and reusing of PET has turned into an imperative procedure from the ecological perspective and it has given business opportunity because of far reaching use and accessibilityof PET polymer. Also another source of pollution to the environment was the corrosion of materials. Corrosion is the deterioration and loss of a material and its critical properties due to chemical, electrochemical and other reactions of the exposed material surface with the surrounding environment. Understanding corrosion mechanisms allow to use corrosion-resistant materials and altering designs. Organic inhibitors are very efficient to protect the metals from corrosion in all chemicals (acidic, basic and salt) media. There were many types of corrosion inhibitors and the organic inhibitor are being applied widely to protect metals from corrosion in many aggressive media. The aim of this study is to utilize waste PET-bottles will be depolarized by 2,2-dithioethanol to produce (Bis(2-((2-hydroxyethyl) thio) ethyl) terephthalate (BHTE), then by reacting of (BHTE) with maleic anhydride to produce Bis (2-((6-Mono malic acid –hydroxyethyl ester) sulfanyl) ethyl terephthalate(BHMET). The prepared (BHMET) will be used as corrosion inhibitor andits efficiency to protect the carbon steel in acidic will be assessed. Materials and Methods: Depolymerization of PET waste done with 2,2-dithioethanol. The weight proportion of PET to 2,2-dithioethanol 1:8 (wt%) and zinc acetate (0.5 wt% based on PET) was added as catalyst. Temperature of the reaction mixture was between 160-180 oC for 12 h, then the reaction mixture was kept at 140 oC for 3 h, then allowed to cool to room temperature. With vigorous agitation distilled water in excess to the reaction mixture to allow the black liquid viscous compound oligomer of Bis(2-((2-hydroxyethyl) thio) ethyl terephthalate (BHET) to precipitate. In a three neck round bottom (250 ml) attached with mechanical stirrer and thermometer (5.7gm) of (BHET) compound was added and heated for (15 min.) at (60 OC). Then (2.5gm) of malic anhydride and (1%) sulfuric acid was added. By the mechanical stirrer the mixture was mixed for (50 min.) at temperature (80OC). After the reaction the mixture was washed with distilled water to avoid the acid residue. Scheme (1) shows the mechanism for the prepared (BHMET) corrosion inhibitor.

In the present work, we report synthesis, structural elucidation and photophysical properties of new pentacoordinated Zn(II) porphyrinates (1-2). Complexes with formula [Zn(TEBOP)(DABCO)](DABCO) (1) [TEBOP = meso-tetrakis(ethyl-4(4-butyryl)oxyphenyl) porphyrinato), DABCO = 1,4-diazabicyclo [2.2.2] octane], and (2) [Zn(TEBOP)(pyz)] [pyz = pyrazine] have been studied to explore the effects of axial ligand on the structural and photophysical properties of [Zn(TEBOP)]. Both the solution and solid-state characterization unambiguously confirmed the pentacordinated nature of the complexes 1 and 2. The X-ray molecular structures showed that these complexes exhibited high ruffling deformation. We showed here that some of the optical properties (absorption features and quantum yield) could be modulated by varying the axial ligand whereas emission wavelength (λem) and lifetime (τf) values were found to remain unchanged. Electrochemical studies suggested that the characteristic reduction and oxidation potentials of the porphyrin ring varied with the axial ligand. Finally, [Zn(TEBOP)] and complexes 1 and 2 were checked for the oxidative degradation of methylene blue (C0 = 30 mg/L, T = 22°C, pH = 6, H2O2 = 4 mL/L). The degradation yields followed the order: [Zn(TEBOP)] + H2O2 (47%) > 2 (38.5.9%) > 1 (26.9%).

The design of metalloporphyrins has attracted the attention of scientists owing to their valuable properties. In this work, the synthesis of meso-tetraphenyl porphyrin H2TPP (I), meso-tetraphenylporphyrinato-chromium(III) complex [CrIII(TPP)Cl] (II), and bis(cyano) meso-tetraphenylporphyrinato-chromium(III) complex [K(2 2 2)] [CrIII(TPP)(CN)2] 2.(C7H6O2) (III) was described. The physicochemical properties of (ll)-(IIII) were investigated. X-ray molecular structure of (III) displayed that the crystal lattice of the six-coordinated chromium (III) coordination compound, was made by two-dimensional chain pairs parallel to the [0 1 0] direction sustained by C__H…Cg and Cg…Cg π inter and intra-molecular interactions. Hirshfeld surface analysis allowed us to understand the intermolecular contacts, where the fingerprint plot provided the information about the percentage contribution. UV–vis data showed a red-shift for the chromium complex and slightly blue-shift after coordination with cyano axial ligand. The Eg-op value suggested that (I)-(III) compounds are semi-conductor. The complex (II) efficiently and promptly degraded calmagite dye solution at a yield of 100% (calmagite = 40 mg/L, pH = 6, time = 10 min, catalyst dose = 3 mg, H2O2 dose = 4 mL/L, and T = 20 °C).

The precursor (5,10,15,20)-tetratolylporphyrin (H2TTP) (1) and Zn(II) complex (5,10,15,20)-tetratolylporphyrinato)zinc(II) [Zn(TTP)] (2) have been synthesized and utilized to afford a novel complex (3) bearing pyrazine as fifth coordination site on axial position, i.e. (pyrazine)(5,10,15,20-tetratolylporphyrinato)zinc(II) hemi-pyrazine hemidichloromethane solvate [Zn(TTP) (pyz)]0.0.5(pyz.CH2Cl2). Photophysical, electrochemical and X-ray diffraction were investigated. The single-crystal X-ray analysis indicated that in complex (3) (i) Zn(II) ion is penta coordinated, (ii) slight displacement of Zn atom by −0.28 A towards the axial ligand (pyrazine) and (iii) the crystal lattice is made up of two dimensional layers stabilised by C−H…Cg intra- and intermolecular interactions (Cg is the centroid of pyrrole ring). Optical absorption studies revealed a redshifted of the Soret (B) and Q bands of the Zn-porphyrins complexes. Contrarily, a hypsochromic shift of Q bands in emission spectra of the complexes is noted as compared to the H2TPP. Lifetime of the electrons in (1–3) were determined and compared. Overall, this study would assist in understanding the impact of incorporation of pyrazine at the axial position on optical and electronic properties. Cyclic voltammetry (CV) was applied for the study of the electrochemical behavior of both (2) and (3) complexes in 0.2 M Tetra-n-butyl ammonium perchlorate (TBAP) solution in CH2Cl2. The results of electrochemical confirmed the potentials redox peaks shift more negative ca 60 mV to that is caused by the coordination of pyrazine ligand.

A mononuclear tetrahedral Zn(II) complex [Zn(L)2](1)[HL = 2-(benzylimino)methyl)phenol] with phenol based bi-dentate N,O donor ligand have been prepared. The compound is characterized by various spectroscopic tools and the structure of the complex is solved by single crystal X-ray diffractometer. The tetrahedral Zn(II) complex crystallized in monoclinic space group I2/awith a = 12.2908(3) (A), b = 9.1041(2) (A), c = 19.9812(7) and β = 96.1466(10)°.Cyclic voltametric study of the complex 1 gives an irreversible oxidation peak due to ligand based oxidation of the phenol moiety to the phenoxyl radical. This compound also shows a strong emission band at 455 nm. The reported Zn(II) complex exhibits catecholase activity in methanol solvent under aerobic condition.The Kcatvalue for 1 in methanol is 8.411 × 103 h−1. The conversion of 3,5-di-tert-butyl catechol (3,5 DTBC) to 3,5-di-tert-butyl quinone (3,5 DTBQ) is catalysed by mono nuclear Zn(II) complex and the reaction proceeds through the generation of ligand centered phenoxyl radical.

Sulphur and nitrogen containing organic compounds are gaining importance in synthetic and pharmaceutical fields. Thiazoles are a heterocyclic organic compound is well known intermediates in thesynthesis of clinically important heterocycles such as 4-thiozolidinones and benzothiozoles. Thiazoles are found in medicaments like vitamin-B, sulphathiozoles, promizole, niridazole, aminotrizole and tetramisole. Therefore, and because of the importance of these compounds, the understanding and study of the mechanism and kinetic of their reactions are particularly important.

In response to the energy crisis, rising fossil fuel costs and global climate warming, this study focuses on the electrocatalytic reduction of proton into hydrogen using an iron sulfur cluster in the presence of pentafluorothiophenol. The direct reduction of pentafluorothiophenol at vitreous carbon electrode occurs at E p -1.3 V vs Ag/AgCl in Tetrabutylammonium tetrafluoroborate [Bu 4 N][BF 4 ]-DMF solution. Interestingly, in the presence of Iron Sulfur Cluster [Fe 4 S 4 (SPh) 4 ][Bu 4 N] 2 , the reduction potential shifts significantly to -0.98 V vs Ag/AgCl. Based on gas chromatography analysis, the formation of H 2 has been confirmed with a current efficiency of ca. 63% after two hours, while the chemical yield at the carbon electrode was about 46%. On the other hand, no H 2 gas was detected without catalyst. Importantly, the increment of the concentration of acid (up to 18 equivalents) led to a positive shifting in the reduction potential until a value of 0.18 V. These results reflect the exquisite electrocatalytic efficiency of the protein-like iron sulfur cluster in Hydrogen Evolution Reaction (HER).