Thermal Decomposition Steps Research Articles

Utilizing sustainable trichalcogenide semiconductor BaS:MnS:DyS to maximize supercapacitor efficiency via innovative single-source precursor method

Electrochemical energy storage has garnered significant attention from the scientific community and energy stakeholders due to its prospective applications, including e-vehicles. The present work aims to improve charge-storage device performance through the use of the novel semiconductor chalcogenide BaS:MnS:DyS, which is synthesized by chelating with diethyldithiocarbamate ligand. Remarkable photo-activity was detected for this semiconductor with an energy band gap of 3.59 eV. With mixed crystalline phases, the generated chalcogenide had an average crystallite size of 18.73 nm, exhibiting auspicious crystallinity. Furthermore, infrared spectroscopy was used to identify metallic sulfide connections, which were found to range between 400 and 967 cm−1. Double step thermal decomposition was confirmed by thermogravimetric analysis. A greater volume-surface area ratio and the existence of many sites were suggested by particles with varying shapes and a fusion resembling rod. With a background electrolyte of 1 M KOH, a conventional three-electrode setup was used to assess the BaS:MnS:DyS electrochemical performance. With a specific power density of 10826.7 W kg−1 and a specific capacitance of up to 824.13 F g−1, BaS:MnS:DyS is an excellent electrode material for energy storage applications. This noteworthy electrochemical performance was further substantiated by the similar series resistance (Rs) = 0.77 Ω.

Pyrolysis of folic acid: Identification of gaseous/volatile products and structural evolution of N-doped graphitic carbon

Folic acid (FA) is a low-cost and suitable source for producing different N-doped carbon materials by pyrolysis. However, the pyrolytic steps of FA are not entirely understood, particularly above 350 °C, which hampers the intelligent design of tailor-made carbon materials by a one-pot route. In this work, the pyrolytic decomposition steps of FA were investigated by simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (TGA-DSC). The released gaseous/volatile products were probed by coupling TGA to infrared spectroscopy and mass spectrometry (TGA-FTIR-MS). Considering the thermal analysis data, FA was pyrolysed in a furnace at 350, 430, 570, 800, and 1000 °C, and the products were analysed by X-ray diffractometry (XRD), vibrational spectroscopy, and X-ray photoelectron spectroscopy. In situ high-temperature X-ray diffractometry (HT-XRD) experiments were also conducted under the nitrogen atmosphere. According to the data set, insights about FA decomposition steps could be proposed, including gaseous/volatile products released during the process and the structural evolution of N-doped graphitic carbon. The formation of carbonaceous material initiated between 200 and 350 °C through polymerisation/condensation reactions, and this step was marked by the release of 2-pyrrolidone and aniline. The graphitisation was enhanced above 350 °C, increasing graphitic nitrogen while the amide groups vanished. The process was accompanied by deoxygenation (i.e., CO and CO2 release) and denitrogenation (e.g., NH3, HNCO, and HCN) reactions. In the 570–800 °C range, the N-enrichment of carbon material (N-pyridine, N-pyrrole/Csp2-N in 5,7-membered rings, and nitrile) could occur by the reaction of released NH3 over the char surface. Graphitic-like structures containing mainly N-graphite and N-pyridine were obtained above 800 °C. The original data about the thermal decomposition steps of FA allow for optimising the synthesis of N-doped carbon materials suitable for applications in adsorption, sensing, catalysis, and energy storage.

Impact of Particle Size on the Nonlinear Magnetic Response of Iron Oxide Nanoparticles during Frequency Mixing Magnetic Detection.

Magnetic nanoparticles (MNPs), particularly iron oxide nanoparticles (IONPs), play a pivotal role in biomedical applications ranging from magnetic resonance imaging (MRI) enhancement and cancer hyperthermia treatments to biosensing. This study focuses on the synthesis, characterization, and application of IONPs with two different size distributions for frequency mixing magnetic detection (FMMD), a technique that leverages the nonlinear magnetization properties of MNPs for sensitive biosensing. IONPs are synthesized through thermal decomposition and subsequent growth steps. Our findings highlight the critical influence of IONP size on the FMMD signal, demonstrating that larger particles contribute dominantly to the FMMD signal. This research advances our understanding of IONP behavior, underscoring the importance of size in their application in advanced diagnostic tools.

One step synthesis of novel Cu3N/Cu2O/C3N4/Cu composite and their photocatalytic reduction activities

Copper nitride/cuprous oxide/carbon nitride/copper (Cu3N/Cu2O/C3N4/Cu) composite material was synthesized by one step thermal decomposition of copper-melamine complexes under N2 atmosphere. The as-synthesized powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The XRD analysis showed the mix phase of Cu3N, Cu2O, C3N4 and Cu. The photocatalytic activities of Cu3N/Cu2O/C3N4/Cu composite photocatalysts were evaluated by testing the photoreduction of chromium (VI) under UV–visible light irradiation. The results indicated that the synthesized samples are attractive photocatalysts for reduction of chromium (VI) under UV light irradiation. The photoreduction efficiencies of Cu3N/Cu2O/C3N4/Cu composite at 550 °C with TEOA induced by UV light within 120 min were 92.03 % caused by charge diffusion at the Cu3N/Cu2O/C3N4/Cu interface. The results indicated that the synthesized samples are attractive photocatalysts for reduction of chromium (VI) under UV light irradiation.

Study of using cork powder as an adjuvant bio-flame retardant in acrylonitrile-butadiene-styrene flame retardant formulations

By having a challenging prospect of developing more environmentally friendly flame-retardant (FR) acrylonitrile-butadiene-styrene (ABS) formulations, an initial study related to the effect of combining ammonium polyphosphate (APP) with cork powder (C), a bio-waste of the cork industry on ABS-FR thermal stability and fire performance is proposed and discussed in the present work. ABS composites with a global filler weight content of 30 wt.% were prepared by using a melt-compounding process. Two different types of thermal decomposition behavior, assessed by means of thermogravimetric analysis (TGA), were observed for ABS/C/APP composites. For formulations with C/APP weight ratio < 1, the thermal decomposition of APP polyphosphate network was shifted to lower temperature. On the other hand, when C/APP ratio was ≥ 1, a new thermal decomposition (TD) step related to an earlier thermal decomposition of cork components was registered between 320 °C and 370 °C. Moreover, by means of Fourier-transform infrared spectroscopy (FTIR) analysis of the pyrolysis gasses, a broader temperature range of ammonia and water release was noticed when APP and C were simultaneously incorporated in ABS. In addition, a micro-scale combustion calorimeter (MCC) analysis revealed that replacing APP by cork led to a decrease of the heat release capacity (HRC) and an increase of the residue formation compared to when only APP was present in ABS composite. Furthermore, forced flaming fire characterization of ABS formulations, studied by means of cone calorimetry (CC), revealed that replacing 20 wt.% of APP by cork (ABS/20C/10APP) led to a similar fire performance to the ABS formulation with 30 wt.% of APP (ABS/30APP). A similar trend under horizontal UL-94 was observed, nevertheless, for the composite with cork in its composition no dripping was noticed. Additionally, by only replacing a 3 wt.% of APP (ABS/3C/27APP) by cork an optimum improvement in fire retardancy was achieved, with the highest efficiency in reducing the peak heat release rate (pHRR) of 21 % regarding ABS/30APP. These results have been related to the chemical interaction between APP and cork components in the condensed phase confirmed by the observance of a more intense P-O-C absorbance peak of the CC residue of ABS/3C/27APP, analyzed by means of FTIR. This composite also showed a more cohesive and expanded char layer, observed by scanning electron microscopy (SEM), which acted as a more efficient protective barrier, reducing heat and mass transfer phenomena during combustion which also led to the highest reduction in linear burning rate (LBR) under horizontal UL-94.

Synthesis, crystal structure analysis, catalytic and biological activities of (H2en)3{V10O28}.6H2O. An improved refinement

The hybrid material, (H2en)3{V10O28}.6H2O (1), containing decavanadate units was synthesized by a wet chemistry method using ethylenediamine (en) as a structure-directing agent. It crystallizes in the monoclinic system, space group C2/c, with cell parameters (Å, °): a = 20.2028 (3), b = 17.0629 (3), c = 10.5541 (2), β= 104.2045 (16). The crystal structure forms a 3D framework of isolated [V10O28]6− monomers, ethylenediammonium cations, and H2O molecules linked through NH···O and OH···O hydrogen bonds. The Fourier transform infrared spectroscopy exhibits characteristic bands corresponding to decavanadate groups and organic molecules. The thermal decomposition steps of the hybrid compound show mainly the loss of the organic moieties and the water molecules. The decavanadate compound's catalytic activity was evaluated by oxidizing methylene blue (MB) with hydrogen peroxide. The biological activity of 1 yielded mediocre results.

A comparative exergoenvironmental assessment of thermochemical copper-chlorine cycles for sustainable hydrogen production

Hydrogen is one of the highly promising clean solutions to address the concerns of energy security in the future given the rapid rate of depletion of naturally occurring hydrocarbon sources. However, it is of immense importance that hydrogen is obtained through sources that ensure sustainability. Thermochemical water-splitting processes are among such routes of hydrogen production that are both sustainable and environmentally benign. Thus, this study focuses on assessing the copper-chlorine thermochemical cycles that are among the more promising cycles of the chlorine family in terms of efficiency and cost-effectiveness. Moreover, this study considers a comparative exergoenvironmental evaluation of the four variants of the copper-chlorine cycle that vary in the number and the nature of steps. A comparison in this regard is carried out between the various steps of each cycle in terms of the component-associated environmental impact rates and environmental impact rates of energy transfer as well as the overall environmental impacts of all cycles. In addition, a comparison of the global warming potential of hydrogen synthesized through utilizing various electricity sources is also performed. Based on our evaluations, hydrolysis and electrolysis are the common steps in the five-step cycle, the four-step cycle, and the three-step cycle configuration 1 yielding the highest component-associated environmental impact rates and environmental impact rates of energy transfer, respectively. Conversely, in the three-step cycle configuration 2, the electrolysis and thermal decomposition steps yield the highest corresponding values, respectively. In addition, the three-step cycle configuration 2 (4,869 mPts/h) and the five-step cycle (3,194 mPts/h) have the highest and the lowest component-associated environmental impact rates, respectively while the five-step (530,694 mPts/h) and the four-step (248,050 mPts/h) cycles result in the highest and the lowest environmental impact rates of energy transfer, respectively.

New penta-Coordinated Cadmium(II) Complexes: Synthesis, Characterization, Thermal, Antimicrobial, Antioxidant and Cytotoxicity Properties.

In this paper, a new tridentate Schiff base ligand (L) with nitrogen donor atoms and its cadmium(II) complexes with the general formula of CdLX2 (X=Cl-, Br-, I-, SCN-, N3 -, NO3 -) have been synthesized and characterized by physical and spectral (FT/IR, UV-Vis, Mass, and 1H, 13C NMR spectroscopies) methods. Also nano-structured cadmium chloride and bromide complexes were synthesized by sonochemical method and then used to prepare nanostructured cadmium oxide confirmed by XRD and SEM techniques. Thermal behavior of the compounds was studied in the temperature range of 25 to 900 °C under N2 atmosphere at a heating rate of 20 °C/ min. Moreover, thermo-kinetic activation parameters of thermal decomposition steps were calculated according to the Coats-Redfern relationship. Antimicrobial activities of the synthesized compounds against two gram-positive and two gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and two fungi of Candida albicans and Aspergillus niger were investigated by well diffusion method. SEM technique was used to monitor the morphological changes of the bacteria treated with the compounds. The 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and the ferric reducing antioxidant power (FRAP) methods were used to evaluate the antioxidant ability of the ligand and its cadmium(II) complexes. In final, the cytotoxicity properties of the ligand and some cadmium(II) complexes against PC3 cancer cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) bioassay and nitric oxide (NO) level measurement. The morphological changes of prostate cancer (PC3) cells due to treatment with the ligand and its complexes confirmed their anticancer effectiveness.

Insights into oxidant matching with green gas generator 5-aminotetrazole from aspects of thermal decomposition behavior, kinetics and combustion mechanism

The green gas generator 5-aminotetrazole (5-AT) is widely applied as an energetic material due to its exceptional characteristics. To investigate the impact of oxidants on the decomposition performance of 5-AT, we prepared three samples using three different oxidants (Sr(NO3)2, KNO3, and KClO4) along with 5-AT under the principle of zero oxygen balance. Then, thermal behavior of the three samples was examined using TG-DTA and TG-FTIR, and their activation energies for each reaction stage were calculated using iso-conversional methods. Results show that the decomposition of these samples occurs in multiple reaction stages and all oxidants, particularly KNO3, facilitate the thermal decomposition of 5-AT. Furthermore, the detailed decomposition mechanism of 5-AT with oxidants was speculated, including that there are two simultaneous ring-opening paths in the first thermal decomposition step of each 5-AT isomer. Eventually, this research can give a meaningful instruction to the formulation design of gas-generation propellant with fewer restrictions in their application.

Ab Initio and Kinetic Modeling of β-d-Xylopyranose under Fast Pyrolysis Conditions.

Lignocellulosic biomass is an abundant renewable resource that can be upgraded to chemical and fuel products through a range of thermal conversion processes. Fast pyrolysis is a promising technology that uses high temperatures and fast heating rates to convert lignocellulose into bio-oils in high yields in the absence of oxygen. Hemicellulose is one of the three major components of lignocellulosic biomass and is a highly branched heteropolymer structure made of pentose, hexose sugars, and sugar acids. In this study, β-d-xylopyranose is proposed as a model structural motif for the essential chemical structure of hemicellulose. The gas-phase pyrolytic reactivity of β-d-xylopyranose is thoroughly investigated using computational strategies rooted in quantum chemistry. In particular, its thermal degradation potential energy surfaces are computed employing Minnesota global hybrid functional M06-2X in conjunction with the 6-311++G(d,p) Pople basis set. Electronic energies are further refined by performing DLPNO-CCSD(T)-F12 single-point calculations on top of M06-2X geometries using the cc-pVTZ-F12 basis set. Conformational analysis for minima and transition states is performed with state-of-the-art semiempirical quantum chemical methods coupled with metadynamics simulations. Key thermodynamic quantities (free energies, barrier heights, enthalpies of formation, and heat capacities) are computed. Rate coefficients for the initial steps of thermal decomposition are computed by means of reaction rate theory. For the first time, a detailed elementary reaction kinetic model for β-d-xylopyranose is developed by utilizing the thermodynamic and kinetic information acquired from the aforementioned calculations. This model specifically targets the initial stages of β-d-xylopyranose pyrolysis in the high-pressure limit, aiming to gain a deeper understanding of its reaction kinetics. This approach establishes a systematic strategy for exploring reactive pathways, evaluating competing parallel reactions, and selectively accepting or discarding pathways based on the analysis. The findings suggest that acyclic d-xylose plays a significant role as an intermediary in the production of key pyrolytic compounds during the pyrolysis of xylose. These compounds include furfural, anhydro-d-xylopyranose, glycolaldehyde, and dihydrofuran-3(2H)-one.

Characterization of enalapril maleate: An approach using thermoanalytical, thermokinetic and spectroscopic techniques

Enalapril maleate is a widely used drug for the treatment of cardiovascular diseases. Its mechanism of action is to inhibit the angiotensin-converting enzyme selectively. Therefore, it is metabolized to enalaprilat by liver cells. The thermal behavior of enalapril maleate was investigated by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), and evolved gas analysis by simultaneous thermogravimetry and differential scanning calorimetry coupled infrared spectroscopy (TG-DSC-FTIR). The results provided information on thermal stability, purity, thermal decomposition steps, and the main products formed in the heating. The enalapril maleate was found to be stable up to 148 ?C. Above this temperature causes thermal degradation of the substance, which occurs in two stages in an inert atmosphere (N2) and three stages in an oxidizing atmosphere (air). Through the TG-DSC-FTIR the released gases were identified as maleic anhydride as a thermal decomposition intermediate. DSC analysis showed that the material obtained 99.5% purity, which indicates high purity. Employing both the Kissinger and Friedman equations, alongside Model Fitting methods, the study reveals key insights. The Kissinger method unveils an apparent activation energy of 47.07?15.45 kJ mol?? for the complete thermal breakdown, a finding corroborated by the Friedman method. Model Fitting methods, the article applies them, yielding an apparent activation energy of 55.70?3.4 kJ mol?? with a three-dimensional diffusion thermal degradation model.

Novel cadmium (II) N2O2‐Schiff base compounds: X‐ray crystal structure, Hirshfeld surface study, thermal behavior, antimicrobial, DNA cleavage power, antioxidant, and cytotoxicity activity

A new N2O2‐tetradentate Schiff base ligand entitled as N,N′‐((ethane‐1,2‐diybis [oxy])bis (ethan‐2,1‐diyl))bis(3‐(4‐methoxyphenyl)prop‐2‐en‐1‐imine was prepared by direct reaction between 3‐(4‐methoxyphenyl)‐2‐propenal and 1,8‐diamino‐3,6‐dioxaoctane. After characterization of the ligand, some novel cadmium coordination compounds formulated as CdLX2 (X: Cl−, Br−, I−, N3−, SCN−and NO3−) were synthesized and characterized by physical and spectral techniques. Typically crystal structure of cadmium nitrate coordination compound was determined suggesting crystallization in monoclinic system (with space group of I2/a) and a coordination geometry of square anti‐prism around the Cd (II) ion. Moreover, CdLBr2 and CdLI2 compounds were prepared in nanostructured dimensions by sonochemical method confirmed by SEM, EDX, and XRD techniques. In continuation, thermal behavior investigation of the compounds including thermal stabilities, thermal decomposition steps, and thermo‐kinetic parameters was performed based on Coats‐Redfern equations from room temperature to 900 °C. Furthermore, all the compounds were subjected to bioassay against two Gram‐positive bacteria of Staphylococcus aureus and Bacillus subtilis, two Gram‐negative bacteria of Pseudomonas aeruginosa and Escherichia coli, and two fungal strains of Aspergillus oryzae and Candida albicans. The results showed that all the synthesized compounds act well as antimicrobial agents. DNA cleavage power of the materials was also evaluated using extracted DNA from E. coli bacterium. The cytotoxic activities of some compounds were investigated against the prostate cancer cell lines (PC3) and human umbilical vein endothelial cells (HUVEC) (as normal cells) by MTT assay and nitric oxide level evaluation method as compared with cis‐platin confirming anti‐cancer effects of them. Finally, the antioxidant properties of the N2O2‐ligand and its cadmium coordination compounds were examined by DPPH and FRAP methods suggesting all the compounds have good antioxidant activity as compared with standard samples.

Synthesis, characterization, TD‐DFT, molecular docking, biological applications, and solvatochromic studies of some new metal complexes derived from semicarbazone of pyrano[3,2‐c]quinoline‐3‐carboxaldehyde

New Zn(II), Cd(II), VO(IV), and UO2(VI) solvatochromic complexes derived from 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde‐semicarbazone ligand (H2L) were synthesized and established by elemental analyses, spectral (IR, UV, NMR, mass spectra), molar conductivity measurements, magnetic susceptibility, and thermal gravimetric analysis (TGA). The ligand coordinates with metal ions through ONO chelating sites, forming an octahedral geometry arrangement, except UO2(VI) that showed pentagonal bipyramidal geometry. Using Coats–Redfern methodology, the kinetic parameters (Ea, A, ΔH, ΔS, and ΔG) of the thermal decomposition steps were calculated and discussed. The complexes showed solvatochromic behavior that used to estimate the ground and excited state dipole moments. Optimization and structural parameters were carried out by density function theory (DFT) at B3LYP/GENECP method at 6‐311G(d,p) basis set for C, H, N, and O atoms and SDD (Stuttgart/Dresden) basis set for the metal atoms and interrelated with the experimental results. The complexes were tested for antimicrobial efficiency against Gram‐positive bacteria, Gram‐negative bacteria, yeast, and fungi. Also, antitumor activity was investigated against HepG‐2 cell line. Finally, the new synthesized complexes upon subjecting to molecular docking and distinguishable results showed outstanding inhibition results of VEGFR‐2 via achieving a high stabilization level inside the largest pocket of 1YWN protein.

New mixed ligand complexes of lanthanide metal cations containing acesulfame/nicotinamide. Synthesis and structural characterizations

The mixed ligand complexes containing acesulfame and nicotinamide ligands of rare earth metal cations Eu3+, Tb3+, Ho3+, Er3+ and Yb3+ were synthesized and their structural characterizations were examined. The complexes' thermal decomposition steps and structural properties were investigated by chemical analysis, infrared spectroscopy, mass analysis, and solid-state UV-vis spectroscopy and thermal analysis methods. According to the results obtained, it is suggested that the metal cations have six coordination sphere. It is recommended that the geometry of the complexes is distorted octahedral with two nicotinamide ligands that make neutral coordination over the nitrogen atom of the pyridine group, two aqua ligands and two monoanionic monodentate acesulfame ligands that coordinated via the acidic imine nitrogen. The coordination compounds perform charge balances with an anionic acesulfame situated the coordination sphere. Except for the Er3+ metal cation complex, it has been determined that all other structures have one hydrate water. From the thermal analysis curves, it was obtained that oxide derivatives of each metal cation were formed in the reaction pots as the last degradation products of Ho3+, Er3+ and Yb3+ complexes. It has been suggested that sulfate salts of related metal cations remain as thermal decomposition products in Eu3+ and Tb3+ metal cation-centered structures.

Mn(II) and Fe(III) complexes of N'1, N'2-bis((E)-2-hydroxybenzylidene) oxalohydrazide: Synthesis, characterization, DFT studies, biological activity, and ion-flotation separation of Fe(III)

In the present work, a new ligand N'1, N'2-bis((E)-2-hydroxybenzylidene) oxalohydrazide (H4OAS) and its chelates, [Mn2(H2OAS)(H2O)2Cl2].H2O and [Fe2(OAS)(H2O)4Cl2]0·5H2O, have been synthesized and elucidated through a variety of physicochemical techniques, including elemental analysis, melting point, 1H and 13C-NMR, electronic spectra, Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Utilizing the Gaussian 9 software and density functional theory (DFT), computations were done to evaluate the geometries for the synthesized ligand and its complexes. Magnetic studies and electronic spectra suggested that Fe(III) chelate has an octahedron coordination structure, while Mn(II) chelate has a tetrahedral coordination structure. In addition, the IR spectral data showed that the ligand exhibits a binegative tetradentate behavior in [Mn2(H2OAS)(H2O)2Cl2].H2O and as a tetranegative hexadentate in [Fe2(OAS)(H2O)4Cl2]0·5H2O. The thermal study of the prepared complexes has been done and led us to determine the activation parameters of several decomposition steps. The kinetic parameters of the resulting thermal decomposition steps were calculated using two methods (Coats-Redfern and Horowitz-Metzger). Based on the calculated activation energy, the thermal stability order was found to be [Fe2(OAS)(H2O)4Cl2]0·5H2O>[Mn2(H2OAS)(H2O)2Cl2].H2O. The ligand and complexes have also been screened for their antibacterial and antifungal potency against multi-stranded microorganisms including gram-negative bacteria (Escherichia coli), gram-positive bacteria (Staphylococcus aureus), and fungal species (Candida albicans). Furthermore, the in-vitro cytotoxic activity of the prepared compounds has been tested against human hepatocellular carcinoma cells (HePG-2) and the results showed that H4OAS and its Fe(III) complex have average activity against HePG-2 with IC50 values of 9.2 and 11.3 µmol/L, respectively. Finally, the synthesized ligand was utilized as a chelating agent and oleic acid as a surfactant in the ion-flotation procedure to separate Fe(III) from the aqueous media.

Cobalt(II) complexes containing mefenamic acid with imidazole and pyridine based auxiliary ligands: Synthesis, structural investigation and cytotoxic evaluation

The interaction between CoCl2.6H2O and mefenamic acid (2-[(2,3-dimethylphenyl)amino]benzoic acid) in the presence of imidazole and pyridine based ligands resulted in the formation of [Co(mef)2(imi)2]; C-1, [Co(mef)2(nic)2(H2O)2].2H2O; C-2, [Co2(µ-H2O)(µ-mef-O,O')2(mef)2(py)4].CH3CN; C-3, and [Co2(µ-mef-O,O')4(apy)2].2CH3CN; C-4, (mef is monodentate mefenamato, µ-H2O is bridging aqua ligand, µ-mef-O, O' is bridging bidentate mefenamato, imi is imidazole, nic is nicotinamide, py is pyridine, and apy is 2-aminopyridine). The complexes were characterized spectroscopically and by physicochemical properties. Single-crystal X-ray diffraction studies confirmed the structures of the complexes. In C-1, Co(II) is in four-coordinate geometry, while in C-2, Co(II) is in hexa-coordination with two mefenamato carboxylate oxygen atoms, two nitrogen atoms, and two oxygen atoms from two solvent ligands. Complex C-3 consists of two cobalt centers linked by an aqua ligand and bridged by two mefenamato ligands. Furthermore, the octahedral geometry in each Co(II) in C-3 was completed by coordinating two monodentate mefenamato ligands and monodentate pyridine ligands. Similarly, in C-4, a Co-Co bond connects two Co(II) centers in six-coordinate geometry, with four bidentate mefenamato ligands acting as bridges between the two Co(II) and two 2-aminopyridine nitrogen, in monodentate coordination to each Co(II). The lattice solvents in C-2 to C-4 participated in intermolecular hydrogen bonding interactions with the mefenamato ligand. FTIR studies showed the presence of both monodentate and bidentate coordination of the deprotonated carboxylate oxygen atoms of the mefenamato ligand, as well as the coordination of the nitrogen donor ligands in the complexes. TG analysis determined the complexes' thermal stability and decomposition steps and ascertained their compositions, which agreed with the analytical and X-ray crystallography studies. Furthermore, the cytotoxicity of mefenamic acid and the cobalt (II) complexes on lung carcinoma cells (NCIH-460) and breast cells (MDAMB) were assessed using MTT assay. The complexes showed higher cytotoxicity than mefenamic acid against the MDAMB cell line.

Synthesis and Biological Activity and Thermal Analysis of Sulfaquinoxaline Mixed Metal Complexes

New mixed sulfaquinoxaline metal complexes were synthised by reacting sulfanomide ligand with transition metals which were as chlorides (Cr(III), Mn(II), Co(II), Cu(II), Hg(II), Fe(III), Zn(II), Cd(II), Ni(II)). The nine mixed complexes of sulfaquinoxaline is prepared by reflux method and determined by CHN analysis and IR. The results of IR spectral data showed that the binding of metals to the sulfonamidic nitrogen, oxygen of sulfone group and nitrogen of amino group .The geometries of all complexes are octahedral and that proved by magnetic measurements and spectral data. The thermogravimetric analysis (TGA) of mixed metal sulfaquinoxaline complexes and DTA that used to determine thermodynamic parameters of the thermal decomposition steps, Ea, ∆H*and ∆S* are carried out from ambient temperature to 700°C in inert nitrogen atmosphere.

TG/MS/FTIR study on thermal degradation process of clay mineral–polysiloxane nanocomposites

Clay-polymer nanocomposites (CPNs) are an important group of materials that are currently receiving increasing attention. The study of the properties of new CPNs is vital, as it facilitates a deeper understanding of their applicability. This study assessed for the first time the thermal stability of clay-polysiloxane nanocomposite as well as their degradation mechanism under an inert atmosphere with the use of the TG/MS/FTIR (simultaneous mass spectrometry and Fourier transform infrared spectroscopy of off-gases from a thermogravimetric analyzer) technique. Organo-montmorillonite (organo-Mt) nanofiller was introduced at different amounts (0, 1, 2, 4, and 8 wt% in relation to the weight of the polymer matrix) into the structure-controlled polysiloxane network. The polysiloxane matrix was obtained by cross-linking poly(methylhydrosiloxane) with poly(dimethylsiloxane) terminated by vinyldimethylsiloxy groups at both ends. This cross-linking was carried out through a hydrosilylation reaction with an equimolar ratio of Si–H and Si-CH=CH2 groups, in the presence of Karstedt's catalyst. Along with an increased amount of organo-Mt, a deterioration in nanocomposites thermal stability, with an increase in the number of thermal decomposition steps, and changes in the degradation mechanism of polysiloxane matrix were observed. The presence of organo-Mt mainly affected the redistribution of bonds at the silicon atoms during the thermolysis of the studied materials. Regardless of the amount of the mineral nanofiller added, the nanocomposites had a similar residual mass remaining after pyrolysis of the studied CPNs at 1000 °C, which was much lower than that of the initial polysiloxane network.

A Treatise on Furan Cored Schiff Base Cu(II), Ni(II) and Co(III) Complexes Accentuating Their Biological Efficacy: Synthesis, Thermal and Spectroscopic Characterization, DNA Interactions, Antioxidant and Antibacterial Activity Studies.

Three metal complexes [Cu(FMIMDIP)2 ] (1), [Ni(FMIMDIP)2 ] (2) and [Co(FMIMDIP)3 ] (3) where, FMIMDIP=(((furan-2-yl)methylimino)methyl)-4,6-diiodophenol, were synthesized and characterized by various spectroscopy. The analytical data revealed a square planar geometry for 1 and 2 and an octahedral geometry for 3. The kinetic and thermodynamic parameters of the thermal decomposition steps were calculated from the thermograms. The quantum chemical parameters have been calculated using HOMO-LUMO energies and reveal the stability of the complexes. The DNA interaction of 1-3 towards calf-thymus DNA was investigated by absorption titration, fluorescence spectroscopy and gel electrophoresis. All the complexes bind to DNA via intercalation mode with binding constant (Kb ) values of 4.17×103 M-1 to 5.9×104 M-1 and also effectively cleave pBR322 DNA by oxidative and photolytic techniques. The synergistic action of metal chelates with ascorbic acid induced the generation of free radicals. The antibacterial activity of 1-3 was tested against B. thuringiensis, S. pneumoniae, E. coli, and P. putida. Complex 3 has the best activity among all the complexes.

Time-resolved study of thermal decomposition process of (NH4)2[PtCl6]: Intermediates and Pt nucleation

Evolution in crystal, electronic and local atomic structures of Pt in ammonium hexachloroplatinate in the course of thermal decomposition in inert and reducing atmospheres have been studied by Powder X-Ray Diffraction (PXRD) and Quick X-ray Absorption Fine Structure (QXAFS) at Pt L3-edge for deeper understanding the thermally-induced solid state reaction and the formation of metallic nanoparticles. A three-step thermal decomposition mechanism of (NH4)2[PtCl6] in the inert atmosphere with the intermediate products Pt(NH3)2Cl2 and PtCl2 has been found instead one-[G.Meyer, A.Möller, J. Less. Common. Met. 170 (1991) 327–331] and two-step one [Q.Kong, F.Baudelet, J.Han, S.Chagnot, L.Barthe, J.Headspith, R. Goldsbrough, F.E.Picca, O.Spalla, Sci. Rep. 2 (2012) 1018–1025] considered early. In the reducing atmosphere, the thermal decomposition is a two-step process with the formation of the intermediate PtCl2. The best approach to determining the number of thermal decomposition steps turned out to be the express-analysis of QXAFS spectra offered in the papers, based on the simultaneous presentation of the most important parameters extracted from X-ray Absorption Near Edge Structure (XANES) and Fourier transformed Extended XAFS (EXAFS). This express-analysis was tested by comparison with results of various approaches such as conventional EXAFS fitting, linear combination fit (LCF), Multivariate Curve Resolution Alternating Least Squares method (MCR ALS).