Pivalate Research Articles

Exploring the Chemistry of Ruthenium Complexes with a Bidentate Barbiturate‐Imidazo[1,5‐a]pyridinylidene Ligand

AbstractA novel reactivity of 5‐barbiturate imidazo[1,5‐a]pyridinium 1⋅H with [Ru(2‐methylallyl)2(COD)] was explored which led to the formation of an uncommon, zwitterionic complex [Ru(1’)(1⋅H)], composed of the NHC ligand 1’, cyclometallated at one ortho‐methyl position of the N‐mesityl substituent, and the zwitterionic precursor 1⋅H. Barbiturate moieties coordinate either through a η3 mode or through coordination of the anionic oxygen atom to ensure the coordination saturation and stability to the complex. The addition of pivalic acid results in the protonolysis of the Ru‐Calkyl bond and demetallation of the N‐mesityl, while triphenylphosphine and pyridine are able to displace the rather labile 1⋅H ligand. Attempts to incorporate an alkylidene fragment from these complexes led to the isolation of a rare complex 7 bearing an alkylidene tethered to a η5‐cyclopentadienyl ligand formed by phenylacetylene tetramerization.

Highly efficient synthesis of mononuclear Pt-based carboxylic complexes trans-[Py2Pt(OC(O)R)2] (R = Me, But, Ph)

Two novel synthetic routes were suggested for square-planar carboxylic platinum(ii) complexes with acetic, pivalic, and benzoic ligands. In the first method, heating ionic complex [Py4Pt](OAc)2 under reduced pressure gives a molecular compound trans-[Py2Pt(OAc)2] with a moderate yield. In the second method, the same starting compound [Py4Pt](OAc)2 ∙ 6 H2O is melted with pivalic or benzoic acids, which leads to analogous carboxylic trans-complexes with almost quantitative yields.

Investigation of pivalic acid-derived organotin(IV) carboxylates: Synthesis, structural insights, interaction with biomolecules, and computational studies

Herein, six homoleptic and heteroleptic tri-organotin(IV) complexes (1–6) of pivalic acid (HL) were synthesized using 2,2′-bipyridine (bipy) and organotin(IV) chlorides, with a general formula of R3SnL/R3SnLbipy, where R = CH3, C4H9, and C6H5. The structure of the complexes was established in the solid phase via FT-IR spectroscopy and in solution through multinuclear NMR spectroscopy. The variety of coordination modes was implemented by the carboxylate group of pivalic acid, which is reflected in the FT-IR data and also supported by the single crystal XRD analysis for complex 5. The single crystal data revealed the presence of a five-coordinated distorted trigonal bipyramidal geometry for complex 5. The structural and electronic details of the complexes were also evaluated by the application of density functional theory through the Lanl2DZ basis set. The ability of complexes to inhibit the AChE and BChE was assessed in vitro as well as theoretically through molecular docking studies and the results were promising. The complexes 4 and 5 showed high inhibitory potency and could be a potential drug candidate. The DNA binding mode of the complexes was studied using UV–Vis spectroscopy and cyclic voltammetry. The findings revealed that these complexes readily intercalate into DNA via a spontaneous process. Additionally, an effective binding of the complexes with surfactant cetyl trimethyl ammonium bromide (CTAB) through a spontaneous process also proved them valuable in pharmacology.

The structure of tetranuclear zirconium pivalate ZR<sub>4</sub>O<sub>2</sub> [(CH<sub>3</sub>)<sub>3</sub>CCO<sub>2</sub>]<sub>12</sub> according to X-ray diffraction analysis and quantum chemical calculations

The crystal and molecular structure of a polynuclear pivalate complex obtained by the interaction of ZrCl4 with pivalic acid was determined by X-ray diffraction analysis. The compound C71H124O28Zr4 (compound 1) crystallizes in the monoclinic crystal system. The crystal structure was refined in the nonstandard space group I2. The asymmetric part of the structure includes three Zr atoms, six pivalate ligands, a bridging µ3-O oxygen atom, as well as disordered crystallization molecules of pivalic acid with an occupancy of 50% and benzene with an occupancy of 50%. The zirconium complex molecule is a tetranuclear cluster that contains three types of Zr atoms that differ in ligand environment. Comparison of the results of quantum chemical calculations of the model reaction ZrCl4 with acetic acid with the literature data on reactions of ZrCl4 with aliphatic acids have shown the possibility of the formation of both mononuclear Zr(RCO2)4 and polynuclear clusters in this reaction, which is a new route for obtaining polynuclear zirconium clusters. The structure of the clusters formed depends on the steric properties of carboxylate ligands.

Self-Assembled Lanthanide Phosphinate Square Grids (Ln = Er, Dy, and Tb): Dy4 Shows SMM/SMT and Tb4 SMT Behavior.

Tetranuclear [2 × 2] square-grid-like LnIII clusters have been synthesized by reacting LnCl3·6H2O salts with bis[α-hydroxy(p-bromophenyl)methyl]phosphinic acid [R2PO2H, where R = CH(OH)PhBr] and pivalic acid. Single-crystal X-ray diffraction studies show the formation of [Me4N]2[Ln4(μ2-η1:η1-PO2R2)8(η2-CO2But)4(μ4-CO3)] [Ln = Er (1), Dy (2), and Tb (3)]. Direct-current studies reveal significant ferromagnetic interactions between DyIII in 2 and TbIII in 3 and an antiferromagnetic interaction between ErIII in 1. Dynamic magnetic susceptibility measurements confirm a single-molecule magnet (SMM) behavior in both 0 and 1200 Oe applied magnetic fields for 2. Complexes 2 and 3 show single molecular toroic (SMT) behavior with a mixed magnetic moment.

Development of pivalic acid conjugated Nafion modified glassy carbon electrode for sensitive detection of Cu(II) by electrochemical approach

In this work, pivalic acid (pivH) molecule is employed for an electrochemical sensing of copper cations in an aqueous medium. For sensitive as well as selective potential sensor application, pivH was fabricated onto a glassy carbon electrode (GCE) facilitated by adhesive conducting binder, nafion, so as make it selective and effective electrochemical probe (pivH/Nafion/GCE) towards specific heavy metal cations. This newly fabricated pivH/Nafion/GCE reveals enhance electrochemical activity toward copper ions in the presence of other interfering heavy metal cations in phosphate buffer solution (PBS) of pH=7. The calibration plot was linear (r2 = 0.9879) across broad linear dynamic range (LDR) spanning Cu2+ concentration from 0.1 nM to 0.01 M. The sensitivity and detection limit was found to be 0.0212 × 10−2 µAµM−1cm−2 and 0.014 nM, respectively. So, this newly fabricated GCE as selective electrochemical probe offers a sensitive as well as selective detection of Cu2+ cations in real environmental samples using a novel electrochemical, current–potential (I-V), approach, for the first time. Further, we explored pivalic acid for the preparation of new di-nuclear copper complex, [Cu2(piv)4(pivH)2] (where piv = pivalate; pivH=pivalic acid) and characterized by Fourier transform infrared spectroscopy (FTIR) spectroscopy, elemental analysis and single crystal X-ray diffractometry. Density functional theory (DFT) calculations were carried out to confirm the interactions and these calculations well-support to experimental data. In case of deprotonated form of pivH, Molecular Electrostatic Potential (MEP) analysis exhibits electrostatic potential equals to −148.4 kcal/mol which suggest about the strong interaction of –COOH with copper centers. Similarly, interaction energies, the quantum theory of atoms in molecules (QTAIM) study and Natural Bond Orbital (NBO) analysis also favor to experimental work. Thus, this novel study demonstrates an excellent approach for highly selective and sensitive detection of Cu2+ cations in short response time with low detection limit and good reproducibility by using I-V method based on newly designed pivH/Nafion/GCE as selective Cu2+ cationic electrochemical sensor. The experimental data was compactable with theoretical calculations.

Hexa-Fe(III) Carboxylate Complexes Facilitate Aerobic Hydrocarbon Oxidative Functionalization: Rh Catalyzed Oxidative Coupling of Benzene and Ethylene to Form Styrene.

Fe(II) carboxylates react with dioxygen and carboxylic acid to form Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 (X = acetate or pivalate), which is an active oxidant for Rh-catalyzed arene alkenylation. Heating (150-200 °C) the catalyst precursor [(η2-C2H4)2Rh(μ-OAc)]2 with ethylene, benzene, Fe(II) carboxylate, and dioxygen yields styrene >30-fold faster than the reaction with dioxygen in the absence of the Fe(II) carboxylate additive. It is also demonstrated that Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 is an active oxidant under anaerobic conditions, and the reduced material can be reoxidized to Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 by dioxygen. At optimized conditions, a turnover frequency of ∼0.2 s-1 is achieved. Unlike analogous reactions with Cu(II) carboxylate oxidants, which undergo stoichiometric Cu(II)-mediated production of phenyl esters (e.g., phenyl acetate) as side products at temperatures ≥150 °C, no phenyl ester side product is observed when Fe carboxylate additives are used. Kinetic isotope effect experiments using C6H6 and C6D6 give k H/k D = 3.5(3), while the use of protio or monodeutero pivalic acid reveals a small KIE with k H/k D = 1.19(2). First-order dependencies on Fe(II) carboxylate and dioxygen concentration are observed in addition to complicated kinetic dependencies on the concentration of carboxylic acid and ethylene, both of which inhibit the reaction rate at a high concentration. Mechanistic studies are consistent with irreversible benzene C-H activation, ethylene insertion into the formed Rh-Ph bond, β-hydride elimination, and reaction of Rh-H with Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 to regenerate a Rh-carboxylate complex.

Vapor Phase Cross Ketonization of Pivalic Acid with Acetic Acid to Prepare Pinacolone Over Mg-Zr Mixed Oxide Catalysts

Vapor Phase Cross Ketonization of Pivalic Acid with Acetic Acid to Prepare Pinacolone Over Mg-Zr Mixed Oxide Catalysts

In silico pharmacokinetic and therapeutic evaluation of Musa acuminata peels against aluminium chloride-induced hepatotoxicity in adult BALB/c mice.

East Africa (Musa spp.), notably Musa acuminata, "Matooke" a staple and economically important food in the region. Here, 12 selected M. acuminata peels extract (MAPE) bioactive compounds were studied for hepatoprotective potentials in aluminium chloride-induced hepatoxicity in adult BALB/c mice. GC-MS analysis was used to identify active components of MAPE. In silico estimation of the pharmacokinetic, the GCMS-identified compounds' toxicity profile and molecular docking were compared with the standard (Simvastatin) drug. Hepatotoxicity was induced using aluminium-chloride treated with MAPE, followed by biochemical and histopathological examination. Twelve bioactive compounds 2,2-Dichloroacetophenone (72870), Cyclooctasiloxane 18993663), 7-Hydroxy-6,9a-dimethyl-3-methylene-decahydro-azuleno[4,5-b]furan-2,9-dione (534579), all-trans-alpha-Carotene (4369188), Cyclononasiloxane (53438479), 3-Chloro-5-(4-methoxyphenyl)-6,7a-dimethyl-5,6,7,7a-tetrahydro-4H-furo[2,3-c]pyridin-2-one (536708), Pivalic acid (6417), 10,13-Octadecadienoic acid (54284936), Ethyl Linoleate (5282184), Oleic acid (5363269), Tirucallol (101257), Obtusifoliol (65252) were identified by GC-MS. Of these, seven were successfully docked with the target proteins. The compounds possess drug likeness potentials that do not inhibits CYP450 isoforms biotransformation. All the docked compounds were chemoprotective to AMES toxicity, hERGI, hERGII and hepatotoxicity. The animal model reveals MAPE protective effect on liver marker's function while the histological studies show regeneration of the disoriented layers of bile ducts and ameliorate the cellular/histoarchitecture of the hepatic cells induced by AlCl3. The findings indicate that MAPE improved liver functions and ameliorated the hepatic cells' cellular or histoarchitecture induced by AlCl3. Further studies are necessary to elucidate the mechanism action and toxicological evaluation of MAPE's chronic or intermittent use to ascertain its safety in whole organism systems.

Coordination Polymer Based on a Triangular Carboxylate Core {Fe(μ3-O)(μ-O2CR)6} and an Aliphatic Diamine.

Interaction of the pre-organized complex of iron(II) trimethylacetate and 1,10-phenanthroline (phen) [Fe2(piv)4(phen)2] (1) (piv = (Me)3CCO2-)) with 1,6-diaminohexane (dahx) in anhydrous acetonitrile yielded a 1D coordination polymer [Fe3O(piv)6(dahx)1.5]n (2) and an organic salt of pivalic acid (H2dahx)(piv)2 (3). The structure of the obtained compounds was determined by single-crystal X-ray diffraction analysis. The phase purity of the complexes was determined by powder X-ray diffraction analysis. According to the single-crystal X-ray analysis, coordination polymer 2 is formed due to the binding of a triangular carboxylate core {Fe3(μ3-O)(μ-piv)6} with an aliphatic diamine ligand. Thermal behavior was investigated for compounds 1 and 2 in an argon atmosphere.

A combinatorial library of two-component gelators based on acid-base complexes of pivalic acid and tert-butylacetic acid

Multi-component self-assembled systems can form highly ordered, complex architectures with diverse morphologies which can be utilized for various high-tech applications. Moreover, a combinatorial library approach can allow us to screen various backbones at the same time for tailoring the functionalities as desired. We report two series of multi-component salt-based gelators based on pivalic acid and tert-butylacetic acid (TBAA) using same set of amines. The two sets of compounds were scrutinized for their gelation performance in a variety of solvents and compared, in order to assess and validate the basic principles behind gelation behavior. The role of acid and effect of increasing a methylene group on the gelation behavior, rheological properties and morphology has been probed.

Genetic and chemical control of tuberculostearic acid production in Mycobacterium avium subspecies paratuberculosis.

Tuberculostearic acid (TBSA) is a fatty acid unique to mycobacteria and some corynebacteria and has been studied due to its diagnostic value, biofuel properties, and role in membrane dynamics. In this study, we demonstrate that TBSA production can be abrogated either by addition of pivalic acid to mycobacterial growth cultures or by a bfaA gene knockout encoding a flavin adenine dinucleotide (FAD)-binding oxidoreductase. Mycobacterium avium subspecies paratuberculosis (Map) growth and TBSA production were inhibited in 0.5-mg/mL pivalic acid-supplemented cultures, but higher concentrations were needed to have a similar effect in other mycobacteria, including Mycobacterium smegmatis. While Map C-type strains, isolated from cattle and other ruminants, will produce TBSA in the absence of pivalic acid, the S-type Map strains, typically isolated from sheep, do not produce TBSA in any condition. A SAM-dependent methyltransferase encoded by bfaB and FAD-binding oxidoreductase are both required in the two-step biosynthesis of TBSA. However, S-type strains contain a single-nucleotide polymorphism in the bfaA gene, rendering the oxidoreductase enzyme vestigial. This results in the production of an intermediate, termed 10-methylene stearate, which is detected only in S-type strains. Fatty acid methyl ester analysis of a C-type Map bfaA knockout revealed the loss of TBSA production, but the intermediate was present, similar to the S-type strains. Collectively, these results demonstrate the subtle biochemical differences between two primary genetic lineages of Map and other mycobacteria as well as explain the resulting phenotype at the genetic level. These data also suggest that TBSA should not be used as a diagnostic marker for Map.IMPORTANCEBranched-chain fatty acids are a predominant cell wall component among species belonging to the Mycobacterium genus. One of these is TBSA, which is a long-chain middle-branched fatty acid used as a diagnostic marker for Mycobacterium tuberculosis. This fatty acid is also an excellent biolubricant. Control of its production is important for industrial purposes as well as understanding the biology of mycobacteria. In this study, we discovered that a carboxylic acid compound termed pivalic acid inhibits TBSA production in mycobacteria. Furthermore, Map strains from two separate genetic lineages (C-type and S-type) showed differential production of TBSA. Cattle-type strains of Mycobacterium avium subspecies paratuberculosis produce TBSA, while the sheep-type strains do not. This important phenotypic difference is attributed to a single-nucleotide deletion in sheep-type strains of Map. This work sheds further light on the mechanism used by mycobacteria to produce tuberculostearic acid.

Pivalic acid based N-doped carbon dots for drug delivery and antioxidant behaviour

Heteroatom doped surface engineered carbon dots has immense potential not only in their fluorescent sensing but also in nanocarrier for drug molecules and antioxidant behavior. Herein, we report a one-step thermal coupling synthesis of carbon dots from pivalic acid and naturally abundant gelatin (PGCDs). The as-synthesized PGCDs exhibited excellent colloidal stability, biocompatibility, and antioxidant activity. The surface of PGCDs was further modified with anticancer drug molecules to assess their drug delivery capabilities. The drug-loaded PGCDs demonstrated sustained release profiles, indicating their potential for controlled drug delivery applications. For understanding the drug delivery mechanism, the cumulative release data have been fitted into Weibull and Higuchi model. The PGCDs also showed pH sensitive release behavior where acidic environment has a better control in release profile compared to the alkaline pH. The concentration dependent radical activity shows more than 80% activity at below 1 mg/mL PGCDs concentration. Their low toxicity against live human cell lines could promote this PGCDs as a potential versatile nano-vector biomedical research area.

Ligand‐assisted Palladium Catalyzed C5 Arylation Reaction of Imidazoles with Aryl Chlorides

AbstractA series of asymmetric pyridine‐bridged imidazole‐pyridine‐amino acid ligands was successfully synthesized and characterized by HR‐MS, 1H, 13C NMR spectroscopy. These ligands assisted palladium catalyzed C−H bond activation of imidazoles at the C5 position with aryl chlorides and aryl bromides without pivalic acid conditions. Various of less reactive aryl chlorides were allowed to prepare arylated heterocycles. The mechanism study indicated the structure role for amino acid and imidazole.

A new paddle wheel type Cu(II) complex with photoluminescence and photocatalytic properties

A paddle wheel-shaped complex formulated [Cu2(piv)4(CH3OH)2]·1.5(CH3OH)·0.5(H2O) (1) has been synthesized by a reaction of Cu(NO3)2·3H2O with pivalic acid. The structure of the complex is characterized by FTIR, elemental analysis and single X-ray crystallography. The crystal structure demonstrates that complex exhibits a paddle wheel type configuration. The asymmetric unit of 1 is composed of a half molecule due to the existence of an inversion center between the two Cu(II) centers. The oxygen atoms of the pivalate serve as bridging ligands, and the two methanol molecules occupy the axial position. Each pivalate ion has syn-, syn- coordination mode and its geometry may be described as square pyramidal. The complex works well as a photocatalyst, breaking down methylene blue (MB) by 78.26% after 120 minutes of 30 W ultraviolet light exposure. The optimized photocatalytic parameters were as follows; catalyst loading = 40 mg, primary concentration of MB = 15 mg/L, temperature = 323K, and pH = 8. The reaction kinetics were best demonstrated by a pseudo-first-order kinetic model followed by a rate constant of 0.00715 min–1. The reuse of the catalyst over five photocatalytic runs suggested its excellent sustainability and recyclability. Hydroxyl radicals and superoxide anions were found to be active participants in the catalytic reaction, as investigated by scavenging studies. These findings contributed to a deeper understanding of the mechanistic aspects of the photocatalytic reaction. Theoretical investigation is well support to experimental work.

Synthesis of 1,1'-Bicarbazoles by Sequential Iron(III)- and Palladium(II)-Catalyzed Oxidative Coupling Reactions.

The iron(III)-catalyzed oxidative coupling of diarylamines to 2,2'-bis(arylamino)-1,1'-biaryls and subsequent twofold palladium(II)-catalyzed oxidative cyclization provide a convergent synthetic route to 1,1'-bicarbazoles. Screening a range of different palladium(II) salts led to palladium(II) acetate, pivalate, and hexafluoroacetylacetonate as the most efficient catalysts. Remarkably, the twofold palladium(II)-catalyzed oxidative cyclization can also be performed under argon. The mechanism for the oxidative cyclization under an inert gas presumably involves regeneration of the catalytically active palladium(II) species by oxidative addition of pivalic acid.

Synthesis and structures of cobalt-expanded zirconium- and cerium-oxo clusters as precursors for mixed-metal oxide thin films.

Transforming current complementary metal-oxide-semiconductor (CMOS) technology to fabricate memory chips and microprocessors into environmentally friendlier electronics requires the development of new approaches to resource- and energy-efficient electron transport and switching materials. Metal and multi-metal oxide layers play a key role in high-end technical applications. However, these layers are commonly produced through high-energy and high-temperature procedures. Herein, we demonstrate our first attempts to obtain stimuli-responsive mixed-metal oxide thin films from solution-processed molecular precursors under milder conditions. The molecular compounds of interest were prepared by one-pot reactions of a CoII carboxylate complex, triethylamine (Et3N), N-butyldiethanolamine (H2bda), and a hexanuclear complex [Ce6O4(OH)4(piv)12] (Hpiv = pivalic acid) or [Zr6O4(OH)4(ib)12(H2O)]·3Hib (Hib = isobutyric acid) in acetonitrile solution. The resulting charge-neutral, heterometallic coordination compounds display a ligand-supported pentanuclear {CeIV3CoIII2} core (in 1) and a dodecanuclear {ZrIV6CoII6} core (in 2), exhibiting thermal stability up to ca. 100 °C in air. Compound 2 was deposited and analyzed on Au(111) and SiO2/Si(100) surfaces to explore its potential as a single-molecule precursor for the preparation of atomically precise, complex mixed-metal oxide thin films. The adsorption characteristics of it demonstrate the ability to form stable agglomerates on the investigated surfaces.

Iridium-catalyzed meta-selective C–H borylation of phenol derivatives

Regioselective C–H functionalization of aromatics remains a challenge in synthesis, particularly for meta-selective C–H borylations of phenols. Here, pivalic acid promoted iridium-catalyzed meta-selective C–H borylation of phenols is disclosed.

Chemical Transformations of [Pd(OOCMe)4Mn] in the Reactions with 1,10-Phenanthroline and Pivalic Acid

Chemical Transformations of [Pd(OOCMe)4Mn] in the Reactions with 1,10-Phenanthroline and Pivalic Acid

Integrating reaction pathways and downstream separation network for optimal sustainable process route selection

Reducing the environmental impact of chemical production has become a critical objective due to carbon emission regulations and the challenges the carbon market poses. Downstream separation network optimization, which can improve process sustainability by using complex heat exchanger networks, applying advanced separation techniques, optimizing the design/operating parameters, etc., has been researched for many years. However, most optimization work focuses solely on downstream separation sections without considering the selection of raw materials and different reaction pathways. This work aims to develop a mixed integer nonlinear programming (MINLP) optimization model, which integrates reaction pathway selection and downstream separation optimization, to select the optimal sustainable process route for utilizing raw materials or producing products. The objective is to maximize/minimize the process profit/cost. Decision variables such as binary variables, which represent the selection of separation task, key component, heating utility, and continuous variables, which influence the separation mass/energy balance, are considered. By giving parameters like reaction conversion rate, selectivity, and raw material/product price, this optimization model can identify the optimal process route for producing a target product or utilizing a raw material. The optimization model was applied to two case studies: one-step isobutylene and methanol utilization and two-step 1,4-butanediol (BDO) production. The process routes, using isobutylene for pivalic acid production and methanol for gasoline production, have the highest process profit per carbon emission. And the process route, which uses acetylene for BDO production, leads to minimum process cost.