Generic Formula Research Articles

Effect of multivalent ion doping on magnetic, electrical, and dielectric properties of nickel ferrite nanoparticles

The nanoscale spinel structured ferrites co-doped with multi-valence ions are of great interest and proving to be promising for numerous applications. In light of this, herein we report tetravalent titanium ions (Ti4+) and divalent zinc ions (Zn2+) co-doped nickel ferrites with generic formula of NiFe2 − 2xTixZnxO4 (x = 0.00 ≤ x ≤ 0.20 in step of 0.05). The sol gel self combustion method in assistance with citric acid as fuel was employed to prepare the samples. The X-ray diffraction (XRD) analysis with Rietveld refinement was performed to confirm the single-phase cubic spinel structure. The sphere type grain morphology of the samples was revealed by SEM images. The compositional studies carried out by EDAX showed desired formation of the composition with absence of impurities in the samples. The characteristics bands belonging to the spinel ferrites were appeared in IR spectra confirming the successive sample forming. The different surface parameters including surface area and pore volume was estimated using Brunauer-Emmett-Teller (BET) analysis. The low coercive nature with soft magnetism was observed with the co-doping as revealed by M-H plots. The electric and dielectric parameters showed decrementing behaviour with increment in Ti4+-Zn2+ co-doping. This study outcome signifies that the Ti4+-Zn2+ co-doping in nickel ferrites could be a prominent for many nanoelectronics applications.

Incorporating Heterogeneous Interactions for Ecological Biodiversity.

Understanding the behaviors of ecological systems is challenging given their multifaceted complexity. To proceed, theoretical models such as Lotka-Volterra dynamics with random interactions have been investigated by the dynamical mean-field theory to provide insights into underlying principles such as how biodiversity and stability depend on the randomness in interaction strength. Yet the fully connected structures assumed in these previous studies are not realistic, as revealed by a vast amount of empirical data. We derive a generic formula for the abundance distribution under an arbitrary distribution of degree, the number of interacting neighbors, which leads to degree-dependent abundance patterns of species. Notably, in contrast to the fully interacting systems, the number of surviving species can be reduced as the community becomes cooperative in heterogeneous interaction structures. Our study, therefore, demonstrates that properly taking into account heterogeneity in the interspecific interaction structure is indispensable to understanding the diversity in large ecosystems, and our general theoretical framework can apply to a much wider range of interacting many-body systems.

Novel europium(III), terbium(III), and gadolinium(III) Schiff base complexes: Synthesis, structural, photoluminescence, antimicrobial, antioxidant, and molecular docking studies

Three lanthanide (III) complexes, L-Eu, L-Tb, and L-Gd, were synthesized using a Schiff base ligand (H2L) composed of (2,2′-(thiophene-2,5-diylbis(methaneylyl-idene))bis(azaneylyl-idene))diphenol. Complexes with the generic formula LnL(Cl)(H2O)·xH2O, where L is the ligand, was studied using elemental analysis, spectrum analysis (IR, mass- UV–Vis), and molar conductivity. Next, the photoluminescence characteristics of the lanthanide complexes were investigated. An assessment was conducted to ascertain the antioxidant activity of the synthetic compounds compared with that of the stable free radical DPPH. The antibacterial activity of the Schiff base metal complexes was assessed against a strain of yeast as well as against a number of Gram-positive and Gram-negative bacteria. Computational studies were also performed to elucidate the mechanisms of the antimicrobial and antioxidant effects. In molecular docking, 1LL9, 6J2O, 3JPU, 2MBR, and 1HD2 crystal structures were determined as targets and the docking score values of H2L, L-Tb, L-Gd, and L-Eu compounds for these targets were calculated.

First-principles investigation of electronic, structural, and magnetic properties of Si substituted cerium phosphide compounds CeSixP1-x

Cerium compounds have invited enough attention from scientists and researchers with respect to practical and fundamental implications having exotic physical, electronic, and magnetic properties like the kondo effect, anisotropic magnetic order, giant Hall effect and superconductivity. Hereby, we describe the mechanical stability and present the electronic, structural, and magnetic properties of new silicon-doped alloys of Cerium Phosphide with generic formula CeSixP1-x (x=0, 0.25, 0.5, 0.75 and 1.0) by using Wien2k code through DFT formalism. The simulation employs generalized gradient approximation through Perdew Bruke Ernzerhof with spin mode. The computed variables are lattice constants, volume, bulk modulus, pressure derivatives, and energy for structural studies. The partial and total densities of states and electronic energy band structures are calculated for electronic studies of these compounds. The magnetic properties of these compounds are described by computing spin magnetic moments. These doped alloys are predicated on being structurally stable, metallic, and non-magnetic materials.

Application of Bifunctional Layered Double Hydroxide Electrocatalysts to Water Splitting

Water splitting is an area of research which is of pressing interest in addressing climate change. Water splitting provides oxygen and hydrogen as products, with hydrogen finding use as a potential high-density fuel to replace fossil fuels. Water splitting manifests as two half-cell reactions, namely the anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction. The purpose of this project is to synthesise a bifunctional electrocatalyst to use in the water splitting reaction, replacing the rare and expensive transition metals catalysts currently in use such as platinum and ruthenium. The ideal material would exhibit strong performance for both the oxygen evolution reaction and the hydrogen evolution reaction.In this project, Layered Double Hydroxides (LDHs) have been synthesised for use in water splitting. LDHs are a group of ionic compounds characterised by their layered structure of positively charged sheets and an interlayer region consisting of the corresponding anions. LDHs typically contain a bivalent and a trivalent metal as part of the generic formula [M2+ 1–xM3+ x(OH)2][An–]x/n·zH2O. In this project the bivalent metal in use is typically cobalt and the trivalent metal is typically iron. The synthesis developed is a simple, one pot hydrothermal synthesis which can be seen in Figure 1. In this synthesis, the process begins with the precursor materials dissolved in solution. These solutions are mixed and stirred until homogenous. The resultant solution is then heated to form an impure product. Following washing steps and centrifugation a purified powder product is obtained. A variety of metallic salts have been tested for their use in these LDHs with the optimum LDHs selected for further study. The metallic salts used to provide the metals for the LDHs are typically hydrated transition metal nitrates.The LDHs have been characterised and their structure confirmed by a variety of analytical techniques including X-Ray Diffraction and Scanning Electron Microscopy. Simple qualitative analysis has been performed with FTIR spectroscopy. These LDHs have been immobilised on a variety of porous, high surface area materials, including nickel foam and copper foam, to enhance the properties seen in the screening study. These materials allow synthesis of high surface area, reactive electrocatalysts. To enhance the stability of the LDHs, carbon materials have been integrated with the LDHs. Examination of a variety of carbon materials involved post-synthesis mixing of the carbon material and the LDH product or inclusion of the carbon material in the LDH synthesis to form a composite. A variety of carbon materials have been analysed including graphene oxide, carbon black and carbon nanotubes. Figure 1

Quantifying nonuniversal corner free-energy contributions in weakly anisotropic two-dimensional critical systems.

We derive an exact formula for the corner free-energy contribution of weakly anisotropic two-dimensional critical systems in the Ising universality class on rectangular domains, expressed in terms of quantities that specify the anisotropic fluctuations. The resulting expression agrees with numerical exact calculations that we perform for the anisotropic triangular Ising model and quantifies the nonuniversality of the corner term for anisotropic critical two-dimensional systems. Our generic formula is expected to apply also to other weakly-anisotropic critical two-dimensional systems that allow for a conformal field theory description in the isotropic limit. We consider the three-states and four-states Potts models as further specific examples.

Rare Earth Nd3+ Doping Cobalt-Cadmium Nanoferrites Structural, Optical, and Magnetic Properties and Applications

Nanoscale particles of neodymium-substituted cobalt-cadmium generic formula for nanoferrite Co0.4Cd0.6NdxFe2−xO4 samples at X = 0.000, 0.003, 0.005, 0.007, 0.009, and 0.011 were studied. The prepared powders were synthesised at low temperatures using citrate gel auto-combustion process. The synthesised powders were calcined at 500 °C for four hours. The morphological properties of the sintered powders were investigated, and their crystal structure was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD peaks confirmed the spinel ferrite structure. The lattice parameter was calculated from the XRD and showed decreasing trends with 8.442 to 8.308. SEM revealed an irregularly-shaped grain morphology with a homogeneous distribution. Raman spectroscopy analysis showed slight frequency changes in the Raman modes in doped samples, attributed to variations in the cation distribution. The peaks are located at 191, 291, 461, 591, and 671 cm−1. UV spectroscopy studies showed that the energy band gap values decrease with increasing Nd3+ concentration. Direct optical band gap values obtained were 1.238, 1.248, 1.199, 1.135, 1.134, and 1.101 eV with increasing Nd doping. The magnetic hysteresis properties were determined using a SQUID-VSM magnetometer. The hysteresis curves of Co0.4Cd0.6NdxFe2−xO4 nanoparticles show an increase in coercivity with increasing doping concentration. This enhancement is attributed to the multi-domain behaviour.

Synthesis, characterization, and biological activity of cationic ruthenium-arene complexes with sulfur ligands.

Five cationic ruthenium-arene complexes with the generic formula [Ru(SAc)(S2C·NHC)(p-cymene)](PF6) (5a-e) were prepared in almost quantitative yields using a straightforward one-pot, two-step experimental procedure starting from [RuCl2(p-cymene)]2, an imidazol(in)ium-2-dithiocarboxylate (NHC·CS2) zwitterion, KSAc, and KPF6. These half-sandwich compounds were fully characterized by various analytical techniques and the molecular structures of two of them were solved by X-ray diffraction analysis, which revealed the existence of an intramolecular chalcogen bond between the oxygen atom of the thioacetate ligand and a proximal sulfur atom of the dithiocarboxylate unit. DFT calculations showed that the C=S…O charge transfer amounted to 2.4kcalmol-1. The dissolution of [Ru(SAc)(S2C·IMes)(p-cymene)](PF6) (5a) in moist DMSO-d6 at room temperature did not cause the dissociation of its sulfur ligands. Instead, p-cymene was slowly released to afford the 12-electron [Ru(SAc)(S2C·IMes)]+ cation that could be detected by mass spectrometry. Monitoring the solvolysis process by 1H NMR spectroscopy showed that more than 22days were needed to fully decompose the starting ruthenium-arene complex. Compounds 5a-e exhibited a high antiproliferative activity against human glioma Hs683 and human lung carcinoma A549 cancer cells. In particular, the IMes derivative (5a) was the most potent compound of the series, achieving toxicities similar to those displayed by marketed platinum drugs.

New asymptotic expansion formula via Malliavin calculus and its application to rough differential equation driven by fractional Brownian motion

This paper presents a novel generic asymptotic expansion formula of expectations of multidimensional Wiener functionals through a Malliavin calculus technique. The uniform estimate of the asymptotic expansion is shown under a weaker condition on the Malliavin covariance matrix of the target Wiener functional. In particular, the method provides a tractable expansion for the expectation of an irregular functional of the solution to a multidimensional rough differential equation driven by fractional Brownian motion with Hurst index H < 1 / 2, without using complicated fractional integral calculus for the singular kernel. In a numerical experiment, our expansion shows a much better approximation for a probability distribution function than its normal approximation, which demonstrates the validity of the proposed method.

PERform: assessing model performance with predictivity and explainability readiness formula

In the rapidly evolving field of artificial intelligence (AI), explainability has been traditionally assessed in a post-modeling process and is often subjective. In contrary, many quantitative metrics have been routinely used to assess a model’s performance. We proposed a unified formular named PERForm, by incorporating explainability as a weight into the existing statistical metrics to provide an integrated and quantitative measure of both predictivity and explainability to guide model selection, application, and evaluation. PERForm was designed as a generic formula and can be applied to any data types. We applied PERForm on a range of diverse datasets, including DILIst, Tox21, and three MAQC-II benchmark datasets, using various modeling algorithms to predict a total of 73 distinct endpoints. For example, AdaBoost algorithms exhibited superior performance (PERForm AUC for AdaBoost is 0.129 where Linear regression is 0) in DILIst prediction, where linear regression outperformed other models in the majority of Tox21 endpoints (PERForm AUC for linear regression is 0.301 where AdaBoost is 0.283 in average). This research marks a significant step toward comprehensively evaluating the utility of an AI model to advance transparency and interpretability, where the tradeoff between a model’s performance and its interpretability can have profound implications.

Homoleptic ruthenium(II) complexes bearing imidazol(in)ium-2-dithiocarboxylate ligands: synthesis, characterization, and redox properties.

Five cationic ruthenium(II) chelates with the generic formula [Ru(S2C·NHC)3](PF6)2 were readily obtained upon cleavage of the [RuCl2(p-cymene)]2 dimer with representative imidazol(in)ium-2-dithiocarboxylate zwitterions (NHC·CS2) in the presence of KPF6. The homoleptic complexes were fully characterized by various analytical techniques and the molecular structure of one of them was determined by single-crystal X-ray diffraction analysis. As expected, it featured an octahedral RuS6 core surrounded by three imidazol(in)ium rings and their nitrogen substituents. The robustness of the Ru-S bonds combined with the chelate effect of the κ2-S,S'-dithiocarboxylate units and the steric protection imparted by bulky 1,3-diarylimidazol(in)ium groups most likely accounted for the outstanding stability of these species in solution. Cyclic voltammetry showed that the five homoleptic complexes featured characteristic waves for a monoelectronic redox process corresponding to the RuIII/RuII couple with E1/2 values ranging between 0.97 and 1.27 V vs. Ag/AgCl. This half-wave potential was clearly dependent on the nature of their ancillary ligands as the evolution of the Ep,ox values roughly paralleled the basicity sequence of the NHCs used to prepare them, in line with the trends observed when monitoring the chemical shifts of the CS2- unit on 13C NMR spectroscopy and the CS2- asymmetric stretching vibration wavenumbers on IR spectroscopy.

A first-principles theoretical study of structural, electronic, and magnetic properties of lead-doped alloys of praseodymium bismuth compounds PrPbxBi1-x

The magnetic, electronic, and structural properties of the cubic phase of lead-doped alloys of praseodymium bismuth compounds with the generic formula PrPbxBi1-x (x = 0, 0.25, 0.50, 0.75, and 1.0) have been reported in this paper by employing the formalism of density functional theory (DFT). For the analysis of physical properties, we have executed the full-potential linearized augmented plane wave plus local orbit (FPLAPW+lo) technique, while the exchange-correlation potentials in the Kohn-Sham equation (KSE) are implemented within the generalized gradient approximation (GGA) extended by the Perdew-Burke-Ernzerhof (PBE) correction. The structural parameters, lattice constants, volume, bulk modulus, pressure derivatives, and energy have been computed with the Wein2k code by fitting total energy through Murnaghan's equation of state. The structural stability of the compounds has been reported from the spin-polarized calculations. The electronic energy bands and total and partial densities of states of the compounds have been calculated in both majority and minority spins, depicting them as metallic. The similar spectrum intensities of the Pr(5d+4f) and (Pb +Bi)2p states account for the majority of the contribution to the density of states near the Fermi energy level. The spin magnetic moments computed for the supercell of the doped compounds have indicated that they are magnetic materials. From the comparison of spin magnetic moments in the PrBi compound, we noticed an improvement in the magnetic moments after doping lead into the PrBi compound.

Pharmaceutical Market: An Overview

Drug display has a substantial risk in terms of the investigation, occurrence, outcomes, and distribution of drugs generally. It is a dynamic and error-prone aspect of the healthcare production process. An overview of pharmaceuticals is provided in this abstract, with emphasis on their key traits, challenges, and methods.The pharmaceutical industry offers a vast array of brands, including generic drugs, biologics, vaccines, formula drugs, and investments in corporate cures. This is due to the ongoing advancements in science and biological research, as well as the growing demand for realistic scenarios in a range of medical contexts One of the trademarks of pharmaceutical presentations (R&D) is the allure of a significant reliance on testing. It takes a long time, money, and uncertainty to bring a new drug to market. It requires stringent preclinical and objective testing, supervisory permissions, and post-shopping follow-ups to ensure security and efficacy. Patents shield innovations and grant pharmaceutical companies a fenestella of uniqueness that helps them recover their large R&D expenses. However, this industry faces many challenges. Increasing healthcare costs, a rise in regulatory investigations, and pressure from payers and governments on prices have all contributed to a cost curb. In addition, there are still problems with research and development because of the rise in complicated diseases, antibiotic resistance, and the need for integrated healthcare. A shift toward biopharmaceuticals, digital healthcare, and precise therapies are just a few of the noteworthy themes that pharmaceutical advertising has helped to foster recently. The COVID-19 pandemic has increased the number of cure cases, revealing the manufacturing industry's susceptibility to pervasive health crises. Drug display is quite competitive, with minor biotech companies and two multinational alliances vying for market share. To expand device portfolios and gain access to new sciences, partnerships, acquisitions, and mergers are the most common approaches

Investigation on the Effect of Work Flexibility Policy on Job Satisfaction and Performance of Millennial Generation Employees in Start-UP Companies in DKI Jakarta

This study aims to determine the effect of job flexibility policies on job satisfaction and millennial generation employee performance in start-up companies in DKI Jakarta. This research uses a quantitative approach with survey methods. The population of the study, namely start-ups in DKI Jakarta, amounted to 1256. The sampling technique used is multistage random sampling. The determination of the final sample size to be used as respondents refers to the Generic Formula, and a total sample of 294 employees is obtained. The data analysis used is multiple regression analysis. The results of data analysis show that there is a positive and significant influence of work flexibility on the performance of millennial generation employees in start-up companies in DKI Jakarta by 62.6%. Affected by the positive and significant influence of job satisfaction on the performance of millennial generation employees in start-up companies in DKI Jakarta by 42.3%. There is a simultaneous influence (together) between the implementation of work flexibility and job satisfaction on the performance of millennial generation employees in start-up companies in DKI Jakarta by 62.6%.

Increasing the Competitiveness of MSMEs in the Global Market by Integrating Digital Marketing and Environmental Awareness: Case Study of the Implementation of Green Environmental Awareness and Green Product Pricing and Its Impact on Green Product Purchasing

This research aims to increase the competitiveness of MSMEs in the global market by integrating digital marketing and environmental awareness: a case study of the application of green environmental awareness and green product pricing and its impact on green product purchasing. This type of research is quantitative with a cross-sectional approach. The population in this study is all MSMEs assisted by the green-based DKI Jakarta Industry, Trade, Small and Medium Enterprises Cooperative which amounts to 284 MSMEs. The sampling technique used is cluster random sampling. Determination of the sample size using the Generic formula so that the sample obtained amounted to 164 respondents. The main research instrument used was a questionnaire with Likert Scale. The data analysis technique used is Confirmatory Factor Analysis Second Order to determine the value of each instrument factor used with standardized factor loading and t-value criteria. The accepted value in the test was more than 0.5 for standardized factor loading and more than 1.96 for t-value. Structural model analysis is carried out using Struqtural Equation Modeling (SEM). The analysis process was carried out using Lisrel with fit model criteria, namely chi square, GFI, AGFI, NFI and CFI, PNFI, and AIC. The results of the analysis show that there is a direct influence of green marketing on green product purchasing. There is a direct influence of green environmental awareness on green product purchasing. There is a direct influence of green product pricing on green product purchasing. There is a direct influence of green marketing on green environmental awareness. There is a direct influence of green environmental awareness on green product pricing

LIMpy: A Semianalytic Approach to Simulating Multiline Intensity Maps at Millimeter Wavelengths

Mapping of multiple lines such as the fine-structure emission from [C ii] (157.7 μm), [O iii] (52 and 88.4 μm), and rotational emission lines from CO are of particular interest for upcoming line intensity mapping (LIM) experiments at millimeter wavelengths, due to their brightness features. Several upcoming experiments aim to cover a broad range of scientific goals, from detecting signatures of the epoch of reionization to the physics of star formation and its role in galaxy evolution. In this paper, we develop a semianalytic approach to modeling line strengths as functions of the star formation rate (SFR) or infrared luminosity based on observations of local and high-z galaxies. This package, LIMpy (Line Intensity Mapping in Python), estimates the intensity and power spectra of [C ii], [O iii], and CO rotational transition lines up to the J levels (1–0) to (13–12) based both on analytic formalism and on simulations. We develop a relation among halo mass, SFR, and multiline intensities that permits us to construct a generic formula for the evolution of several line strengths up to z ∼ 10. We implement a variety of star formation models and multiline luminosity relations to estimate the astrophysical uncertainties on the intensity power spectrum of these lines. As a demonstration, we predict the signal-to-noise ratio of [C ii] detection for an EoR-Spec-like instrument on the Fred Young Submillimeter Telescope. Furthermore, the ability to use any halo catalog allows the LIMpy code to be easily integrated into existing simulation pipelines, providing a flexible tool to study intensity mapping in the context of complex galaxy formation physics.

Investigation on the impact of cobalt doping on optical, structural and magnetic properties of zinc oxide nanoparticles

In the current article, we investigated the impact of transition metal Co2+ doping in ZnO nanoparticles and its effect on their optical, structural, and magnetic properties. The synthesized nanoparticles have the generic formula Zn1-xCoxO (x = 0.00, 0.03, 0.06, and 0.09). Single-phase hexagonal crystal structure of the synthesized nanopowder was confirmed by x-ray diffractograms. Tauc plots were used to calculate the band gap of all the samples. Multiple emission peaks were observed from the photoluminescence studies. HRTEM was employed to study the particle morphology and the size distribution. X-ray photoelectron (XPS) spectroscopy was performed to investigate the chemical composition of samples. Magnetic measurements were carried out to study the magnetic behaviour of pure and doped ZnO samples. Ferromagnetic behaviour became more prominent with the addition of Co doping, as observed by room temperature M-H plots.

Synthesis, characterization, and catalytic evaluation of palladium PEPPSI complexes bearing unsymmetrical NHC ligands in Suzuki–Miyaura reactions

Seven unsymmetrical imidazolium chlorides featuring a mesityl (Mes) or 2,6-diisopropylphenyl substituent (Dip) on one of their nitrogen atoms and a cycloalkyl group of variable size (cyclopentyl, cyclohexyl, 1-adamantanyl, cycloheptyl, cyclooctyl, or cyclododecyl) on the other one served to prepare a small library of novel palladium PEPPSI complexes with the generic formula [PdCl2(NHC)(Py)]. Three symmetrical compounds featuring the bulky yet flexible 1,3-dicyclododecylimidazol-2-ylidene and the archetypical IMes and IDip ligands were also synthesized. All the products were isolated in modest to satisfactory yields (15–85%) and fully characterized using 1H and 13C NMR spectroscopies. The molecular structures of five of them were determined using single crystal X-ray diffraction analysis, which revealed that, in most cases, the conformational freedom of the N-cycloalkyl moieties subsisted in the crystal phase. Topographic maps and %VBur parameters were computed to quantify the steric requirements of the uNHC ligands. The catalytic activity of the ten complexes was assessed in the Suzuki–Miyaura cross-coupling of phenylboronic acid and aryl halides. The reactions required only a low catalyst loading (0.05–0.25 mol%) and were carried out under mild aerobic conditions in a green, water-based solvent mixture. High yields of biphenyl derivatives were achieved with all the aryl bromides tested, irrespective of the presence of electron-donating or withdrawing substituents on their aromatic ring. When 4-chloro-acetophenone, a representative electron-poor aryl chloride served as substrate, all the complexes featuring cycloalkyl substituents on their NHC ligand became mostly inactive, whereas the IMes and IDip-based catalyst precursors maintained a high activity.

Regulatory Perspective Reverse Engineering Analysis of the Mast Cell Stabilizer and the Histamine Receptor Antagonist (Olopatadine HCl): Instrumental and Classical Methods for Multiple Formulations.

This study evaluates the unknown qualitative (Q1) and quantitative (Q2) formulas for nasal spray and ophthalmic solution formulations of olopatadine HCl by classical and instrumental techniques to match the generic formula with reference-listed drugs to avoid clinical study. Reverse engineering of olopatadine HCl nasal spray 0.6% and ophthalmic solution 0.1, 0.2% formulations was accurately quantified using a simple and sensitive reversed-phase high-performance liquid chromatography (HPLC) method. Both formulations possess similar components, namely ethylenediaminetetraacetic acid (EDTA), benzalkonium chloride (BKC), sodium chloride (NaCl), and dibasic sodium phosphate (DSP). These components were qualitatively and quantitatively determined using the HPLC, osmometry, and titration techniques. With derivatization techniques, EDTA, BKC, and DSP were determined by ion-interaction chromatography. NaCl in the formulation was quantified by measuring the osmolality and using the subtraction method. A titration method was also used. All the employed methods were linear, accurate, precise, and specific. The correlation coefficient was >0.999 for all components in all the methods. The recovery results ranged from 99.1 to 99.7% for EDTA, 99.1-99.4% for BKC, 99.8-100.8% for DSP, and 99.7-100.1% for NaCl. The obtained % relative standard deviation for precision was 0.9% for EDTA, 0.6% for BKC, 0.9% for DSP, and 1.34% for NaCl. The specificity of the methods in the presence of other components, diluent, and the mobile phase was confirmed, and the analytes were specific.

“Greening” Ruthenium–Arene Catalyst Precursors with N-Heterocyclic Carbene Ligands Derived from Caffeine and Theophylline

Two ruthenium–arene complexes with the generic formula [RuCl2(p-cymene)(NHC)] were readily obtained from natural, abundant, and renewable methylxanthine alkaloids used as N-heterocyclic carbene (NHC) precursors. After optimization, the known compound Ru-1 featuring the 1,3,7,9-tetramethylxanthine-8-ylidene ligand was isolated in three steps and 72% overall yield starting from caffeine. Four steps were needed to synthesize complex Ru-2, which sported the bulkier 7-isobutyl-1,3,9-trimethylxanthine-8-ylidene ligand, in 41% overall yield starting from theophylline. Multinuclear NMR analysis confirmed the presence of p-cymene and an NHC ligand within the coordination sphere of both products. Yet, they exhibited a significantly different dynamic behavior in solution at room temperature, due to the larger size of the isobutyl chain compared to a methyl group, which severely restricted the rotation of the arene ligand and caused a loss of symmetry. Complexes Ru-1 and Ru-2 were both highly active catalyst precursors for the transfer hydrogenation of unsaturated substrates with isopropanol under basic conditions (11 examples). They were also efficient promoters for the oxidation of alkenes with sodium periodate. Last but not least, they triggered the synthesis of vinyl esters from 1-hexyne and benzoic acid. For this later reaction, the product distribution varied markedly with the nature of the NHC ligand. Altogether, this study demonstrated that the combination of a labile p-cymene ligand and an ancillary NHC ligand derived from caffeine or theophylline provided an efficient and sustainable access to a wealth of highly active Ru–hydride, −oxo, or −alkyne species that were able to catalyze three miscellaneous organic transformations.