Ketone Complexes Research Articles

Exploring the carbon-chain structure-activity relationship of CO2 and ketone-based absorbents

With regard to the physical absorbents for CO2 removal, the alteration of carbon-chain structure may benefit the CO2 absorption performance. However, the relationship between the carbon-chain structure of ketones absorbents and their CO2 absorption capacity has rarely been studied, and the related mechanism is unclear. In this study, theoretical calculations and thermodynamic experiments were carried out to explore the effects of the carbon-chain length and isomerism of ketones on their CO2 absorption performance. The density functional theory (DFT) simulations show that the F-∥ configuration is more stable than the others for the CO2+ketone complex in most cases. The followings are obtained according to the experimental results, which are pretty consistent with DFT calculations. The dissolution of CO2 in the ketone is a typical physical process. As the number of carbon atom increases, the CO2 absorption capacity of straight-chain ketones increases. Straight-chain ketones exhibit higher CO2 absorption capacity than branched-chain ones. The effect of increasing carbon-chain length and isomerism on CO2 absorption capacity are both stronger for the ketones with fewer carbon atoms; the influence mechanism can be attributed to different degrees of weak hydrogen-bond interaction between CO2 and ketone molecules, suggested by the DFT simulation results. The above conclusions are beneficial for the development of potential CO2 capture absorbents. In addition, the industrial application feasibility of surveyed ketone absorbents is also discussed.

Enantioselective Radical Addition to Ketones through Lewis Acid-Enabled Photoredox Catalysis.

Photocatalysis opens up a new window for carbonyl chemistry. Despite a multitude of photochemical reactions of carbonyl compounds, visible light-induced catalytic asymmetric transformations remain elusive and pose a formidable challenge. Accordingly, the development of simple, efficient, and economic catalytic systems is the ideal pursuit for chemists. Herein, we report an enantioselective radical photoaddition to ketones through a Lewis acid-enabled photoredox catalysis wherein the in situ formed chiral N,N'-dioxide/Sc(III)-ketone complex serves as a temporary photocatalyst to trigger single-electron transfer oxidation of silanes for the generation of nucleophilic radical species, including primary, secondary, and tertiary alkyl radicals, giving various enantioenriched aza-heterocycle-based tertiary alcohols in good to excellent yields and enantioselectivities. The results of electron paramagnetic resonance (EPR) and high-resolution mass spectrum (HRMS) measurements provided favorable evidence for the stereocontrolled radical addition process involved in this reaction.

Design, Synthesis and Evaluation of Novel Derivatives of Curcuminoids with Cytotoxicity.

Curcumin and curcuminoids have been discussed frequently due to their promising functional groups (such as scaffolds of α,β-unsaturated β-diketone, α,β-unsaturated ketone and β′-hydroxy-α,β-unsaturated ketone connected with aromatic rings on both sides) that play an important role in various bioactivities, including antioxidant, anti-inflammatory, anti-proliferation and anticancer activity. A series of novel curcuminoid derivatives (a total of 55 new compounds) and three reference compounds were synthesized with good yields using three-step organic synthesis. The anti-proliferative activities of curcumin derivatives were examined for six human cancer cell lines: HeLaS3, KBvin, MCF-7, HepG2, NCI-H460 and NCI-H460/MX20. Compared to the IC50 values of all the synthesized derivatives, most α,β-unsaturated ketones displayed potent anti-proliferative effects against all six human cancer cell lines, whereas β′-hydroxy-α,β-unsaturated ketones and α,β-unsaturated β-diketones presented moderate anti-proliferative effects. Two potent curcuminoid derivatives were found among all the novel derivatives and reference compounds: (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a). These were selected for further analysis after the evaluation of their anti-proliferative effects against all human cancer cell lines. The results of apoptosis assays revealed that the number of dead cells was increased in early apoptosis and late apoptosis, while cell proliferation was also decreased after applying various concentrations of (E)-5-hydroxy-7-phenyl-1-(3,4,5-trimethoxyphenyl)hept-1-en-3-one (compound 3) and (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) to MCF-7 and HpeG2 cancer cells. Analysis of the gene expression arrays showed that three genes (GADD45B, SESN2 and BBC3) were correlated with the p53 pathway. From the quantitative PCR analysis, it was seen that (1E,4E)-1,7-bis(3,4,5-trimethoxyphenyl)hepta-1,4-dien-3-one (compound MD12a) effectively induced the up-regulated expression of GADD45B, leading to the suppression of MCF-7 cancer cell formation and cell death. Molecular docking analysis was used to predict and sketch the interactions of the GADD45B-α,β-unsaturated ketone complex for help in drug design.

Tuning Anti-Biofilm Activity of Manganese(II) Complexes: Linking Biological Effectiveness of Heteroaromatic Complexes of Alcohol, Aldehyde, Ketone, and Carboxylic Acid with Structural Effects and Redox Activity.

The constantly growing resistance of bacteria to antibiotics and other antibacterial substances has led us to an era in which alternative antimicrobial therapies are urgently required. One promising approach is to target bacterial pathogens using metal complexes. Therefore, we investigated the possibility of utilizing series of manganese(II) complexes with heteroaromatic ligands: Alcohol, aldehyde, ketone, and carboxylic acid as inhibitors for biofilm formation of Pseudomonas aeruginosa. To complete the series mentioned above, Mn-dipyCO-NO3 with dipyridin-2-ylmethanone (dipyCO) was isolated, and then structurally (single-crystal X-ray analysis) and physicochemically characterized (FT-IR, TG, CV, magnetic susceptibility). The antibacterial activity of the compounds against representative Gram-negative and Gram-positive bacteria was also evaluated. It is worth highlighting that the results of the cytotoxicity assays performed (MTT, DHI HoloMonitorM4) indicate high cell viability of the human fibroblast (VH10) in the presence of the Mn(II) complexes. Additionally, the inhibition effect of catalase activity by the complexes was studied. This paper focused on such aspects as studying different types of intermolecular interactions in the crystals of the Mn(II) complexes as well as their possible effect on anti-biofilm activity, the structure–activity relationship of the Mn(II) complexes, and regularity between the electrochemical properties of the Mn(II) complexes and anti-biofilm activity.

Hydrazones and their metal complexes: A short review on their biological potentia

Hydrazones belong to complexes are beneficial in different fields for their essential role in the development of a range of stable complexes in the coordination chemistry. Different researchers have reported the various medicinal properties of hydrazones. Hydrazone and its metal complexes are useful for the detection of some organic components from pharmaceutical formulations. These metallic compounds act as a catalyst for conducting various chemical reactions and help in making different chemical complexes that are effective against bacteria, fungi, and many other microbes. Aromatic hydrazone derivatives can measure the concentration of low molecular weight aldehyde and ketone complexes. Hydrazones possess numerous medicinal properties, including antimicrobial, anti-cancer, antidepressant, anti-tubercular, anti-viral, etc. For the new drug discovery, hydrazones/azomethines are considered to be an important class of compound. From molecular biology to pharmaceutical formulation, organic chemistry, new drug development process, the importance of hydrazone and its metal complexes is immense. The present review aims to highlight the reported biological activities related to hydrazones for the last decade.

Copper Complexes of Benzoylacetone Bis-Thiosemicarbazones: Metal and Ligand Based Redox Reactivity

Bis-thiosemicarbazones derived from the β-diketone benzoylacetone (H3banR, R=Me, Et, Ph) are potentially tetradentate N2S2 ligands whose coordination chemistry with copper is reported. In the absence of oxygen and in the presence of base they form anionic CuII complexes of the fully deprotonated ligands [CuII(banR)]–. Upon exposure to atmospheric oxygen they undergo a complex series of reactions leading to two types of products; one a ligand oxidised ketone complex [CuII(banRO)] and the other an unprecedented dimeric di-CuIII complex [(CuIII(banR))2] depending on the R substituent. Time-resolved UV-vis spectroscopy, cyclic voltammetry, spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy have been used to identify intermediates on the way to stable products formed under both anaerobic and aerobic conditions. It is found that both ligand-centred and Cu-centred oxidation reactions are occurring in parallel leading to this unusually complicated mixture of products.

Astatine partitioning between nitric acid and conventional solvents: indication of covalency in ketone complexation of AtO.

Astatine-211 has been produced at Texas A&M University on the K150 cyclotron, with a yield of 890 ± 80 MBq through the 209Bi(α,2n)211At reaction via an 8 h bombardment with a beam current of 4-8 μA and an α-particle beam energy of 28.8 MeV. The target was then dissolved in HNO3 and the extraction of 211At was investigated into a variety of organic solvents in 1-3 M HNO3. Extraction of 211At with distribution ratios as high as 11.3 ± 0.6, 12.3 ± 0.8, 42.2 ± 2.2, 69 ± 4, and 95 ± 6 were observed for diisopropyl ether, 1-decanol, 1-octanol, 3-octanone, and methyl isobutyl ketone, respectively, while the distribution ratios for 207Bi were ≤0.05 in all cases. The extraction of 211At into both methyl isobutyl ketone and 3-octanone showed a strong, linear dependence on the HNO3 initial aqueous concentration and better extraction than other solvents. DFT calculations show stronger binding between the carbonyl oxygen of the ketone and the At metal center.

Bioinspired iron(II)-β-diketonate and iron(II)-α-hydroxy ketone complexes of a carbanionic N3C ligand: Oxidation of metal center vs C[sbnd]C bond cleavage of co-ligand with dioxygen

Two bioinspired low-spin iron(II)-β-diketonate complexes, [(L1)FeII(BA)] (2) and [(L1)FeII(DBM)] (3), and an iron(II)-α-hydroxy ketone complex [(L1)FeII(HAP)] (4) (L1 = tris(2-pyridylthio)methanido anion, BA = monoanionic benzoylacetone, DBM = monoanionic dibenzoylmethane and HAP = monoanionic 2-hydroxyacetophenone) of a tripodal carbanionic ligand were prepared from an iron(II) precursor complex [(L1)FeII(CH3CN)2](ClO4) (1). The dioxygen reactivity of the complexes (2, 3 and 4) was investigated to evaluate the effect of ligand geometry and of the spin state of iron on the CC bond cleavage of the co-ligands. Complexes 2 and 3 react with dioxygen to yield benzoic acid as a minor product. The major pathway involves the formation of the corresponding iron(III)-β-diketonate complexes, [(L1)FeIII(BA)](ClO4) (2ox-ClO4) and [(L1)FeIII(DBM)](ClO4) (3ox-ClO4). Complex 4, however, undergoes the CC bond cleavage of the iron-coodinated HAP to form benzoic acid as the major product. In the reaction, phenylglyoxal is formed as the minor product with concomitant generation of an iron-oxygen oxidant. The oxidant is able to transfer an oxygen atom to thioanisole and can exchange its oxygen atom with water. The reactivity patterns of the low-spin iron(II) complexes reported here are distinctly different from that of the corresponding high-spin complexes supported by a monoanionic facial N3 ligand. The results emphasize the role of spin-state of iron, the denticity of the supporting ligand, and the nature of co-ligand in affecting the CC bond cleavage reaction.

Formation and Reactivity of Copper Acetylacetone Bis(Thiosemicarbazone) Complexes

The complexation reaction mechanism of acetylacetone bis‐thiosemicarbazone ligands (H2acacR) with CuII is explored using a variety of physical methods. The complexes form via a complicated multistep mechanism that is initiated by ring opening of the pyrazoline form of the ligand and leads, ultimately in air, to an oxidised ketone form of the ligand. Tetradentate N2S2 coordinated forms of the intermediate [Cu(acacR)] are stable only under anaerobic conditions. Upon exposure to air these complexes are cleanly oxidised to the ketone complex [Cu(acacRO)] as shown by X‐ray crystallography, electrochemistry, UV/Vis and EPR spectroscopy. The behavior of these complexes contrasts with those of closely related bis‐dithiocarbazate Schiff bases which stabilise CuIII.

Spectral and Ultrasonic Investigation of Hydrogen Bonded Complexes of Cyclohexanol and Aryl Ketones in DMSO Medium

Spectral and Ultrasonic Investigation of Hydrogen Bonded Complexes of Cyclohexanol and Aryl Ketones in DMSO Medium

Pd(II)-Catalyzed Direct ortho-C-H Acylation of Aromatic Ketones by Oxidative Decarboxylation of α-Oxocarboxylic Acids.

A Pd-catalyzed decarboxylative acylation of aromatic ketones with α-oxocarboxylic acids was developed, and 1,2-diacylbenzenes were formed in up to 90% yield with excellent ortho-selectivity. This work demonstrates the first successful attempt to direct C-H acylation of aromatic ketones without the need for prederivatization to imines. The acylation reaction was inhibited by radical scavengers such as TEMPO, and 2,2,6,6-tetramethylpiperidin-1-yl benzoate, the adduct of TEMPO and a benzoyl radical, has been isolated and characterized. This finding is compatible with the intermediacy of acyl radicals. A mechanism involving the reaction of the palladacyclic complexes of aryl ketones with acyl radicals is proposed.

Phosphinofulvene Enolate Ligands in Ruthenium Complexes by Ferrocene Photolysis under Solar Radiation

Ruthenium complexes containing a new type of phosphine ligand were obtained through photochemical transformations. The process involves the irradiation of (phosphinoferrocenylcarbonyl)ruthenium derivatives with visible light (tungsten halogen lamp) to yield complexes with κ2‐P,O phosphinofulvene enolate ligands after the formal loss of the “CpFe+” (Cp = cyclopentadienyl) entity. A tandem reaction that involves the irradiation of a mixture of a (hydroxymethyl)ferrocenylphosphine ligand and (arene)ruthenium precursors is also possible. The reaction proceeds through the coordination of the hydroxy phosphine ligands, evolution to hydrido ketone (or hydrido aldehyde) complexes and subsequent evolution to the fulvene derivatives. The process also occurs under solar radiation. The photolysis reaction was studied at different wavelengths of the visible spectrum by irradiation with light‐emitting diodes (LEDs). Positive results were obtained when irradiation was performed in the wavelength region corresponding to the metal‐to‐ligand charge‐transfer (MLCT) band that is characteristic of the acylferrocenyl moiety. The use of green light (λ = 530 nm) gave the best results, and the reaction did not proceed under higher‐wavelength light or in the dark. A non‐coordinated phosphinoferrocenylcarbaldehyde ligand also evolved under solar radiation, but a complex mixture was obtained; thus, the selectivity increases significantly if the ruthenium centre is present.

Synthesis and reactivity of di- and tri-metallic complexes containing the TpRu(PPh3) fragment

Treatment of the TpRu complex Tp(PPh3)2RuCl (Tp = HB(pz)3, pz = pyrazolyl) (1) with ethynylferrocene in MeOH gave the trimetallic alkenyl ketone complex Tp(PPh3)Ru{C(Fc) = CHC(O)CH2(Fc)} (Fc=(η5-C5H4)Fe(η5-C5H5)) (2). Intriguingly, a similar reaction was performed in the presence of NaOMe afforded the dimetallic acetylide complex Tp(PPh3)2Ru–CC-Fc (3). A number of new cationic vinylidene complexes [Tp(PPh3)2Ru{ = CC(Fc)CH2R}]+ [4a, R = CN; 4b, R = HCCH2; 4c, R = CHC(CH3)2; 4d, R = Ph] have been prepared by electrophilic addition of organic halides to complex 3. The substitution reaction of 4a with pyrazole is followed by an intramolecular nucleophilic addition of the nitrogen atom at the α-carbon atom and removal of HI to afford the metallacyclic complex, Tp(PPh3)Ru(C3H3NN)CC(Fc) CH2CN (5a). All of the complexes are identified by spectroscopic methods as well as elementary analysis. The structure of 2 has been determined by X-ray diffraction analysis. Pathways for the synthesis of these compounds are proposed.

New pyridyl-pyrazinyl ketones as ligands for Cu(II), Ag(I), Zn(II) and Cd(II) complexes: Anion-dependent hydrolysis of 2,2′-pyridyl-pyrazinyl ketone and unvaried neat forms of its positional isomers

A series of Cu(II), Ag(I), Zn(II) and Cd(II) complexes of new pyridyl-pyrazinyl ketones 2-pyridinyl-2-pyrazinylmethanone (abbreviated as L1), 3-pyridinyl-2-pyrazinylmethanone (L2) and 4-pyridinyl-2-pyrazinylmethanone (L3) has been synthesized and characterized by single crystal X-ray analysis. L1 can takes not only its neat ketone form in [Ag(L1)(NO2)]∞ (1), but also the gem-diol form (L1a) in [Ag(L1a)(CF3CO2)]∞ (2) and [Cu(L1a)2](BF4)2·4H2O (3) via in-situ metal-promoted nucleophilic reaction. L2 and L3 preferentially adopt their ketone forms in zinc(II) and cadmium(II) complexes [Zn(L2)2Cl2] (4), [Cd(L2)2(NO3)2(H2O)2] (5), {[Cd(L2)2(H2O)2](BF4)2·4H2O}∞ (6), {[Cd(L2)2(H2O)2](ClO4)2·4H2O}∞ (7), [Cd(L3)2(H2O)4](NO3)2 (8) and {[Cd4(L3)4(ClO4)2](ClO4)6⋅13H2O}∞ (9). The ligand behavior of L1–L3 in complexes 1–9 are compared to that of di-2-pyridinylmethanone and its positional isomers. The metal-promoted nucleophilic reaction mechanism involving the carbonyl group in coordination complexes of the pyridyl ketone family is probed and discussed. Supramolecular architectures of complexes 1–9 with the various ketones are also observed and discussed.

ChemInform Abstract: Zincocene and Dizincocene N‐Heterocyclic Carbene Complexes and Catalytic Hydrogenation of Imines and Ketones.

AbstractNHC‐complexes of zincocenes are developed and screened as moderately efficient catalyst for the catalytic hydrogenation of imines and ketones.

Zincocene and dizincocene N-heterocyclic carbene complexes and catalytic hydrogenation of imines and ketones.

The N-heterocyclic carbene (NHC) adducts Zn(Cp(R))(2) (NHC)] (Cp(R) =C(5)HMe(4), C(5)H(4) SiMe(3); NHC=ItBu, IDipp (Dipp=2,6-diisopropylphenyl), IMes (Mes=mesityl), SIMes) were prepared and shown to be active catalysts for the hydrogenation of imines, whereas decamethylzincocene [ZnCp*(2)] is highly active for the hydrogenation of ketones in the presence of noncoordinating NHCs. The abnormal carbene complex [Zn(OCHPh(2))(2) (aItBu)](2) was formed from spontaneous rearrangement of the ItBu ligand during incomplete hydrogenation of benzophenone. Two isolated Zn(I) adducts [Zn(2)Cp*(2) (NHC)] (NHC=ItBu, SIMes) are presented and characterized as weak adducts on the basis of (13)C NMR spectroscopic and X-ray diffraction experiments. A mechanistic proposal for the reduction of [ZnCp*(2)] with H(2) to give [Zn(2)Cp*(2)] is discussed.

Unexpected Formation of Highly Strained 2,5‐Dioxa‐3‐Silabicyclo[2.1.0]Pentane by the Reaction of Isolable Dialkylsilylene with Benzil

ABSTRACTThe reaction of isolable dialkylsilylene 1 with benzil gave [1+4] cycloadduct 1,3‐dioxa‐2‐sila‐cyclopent‐4‐ene 2 and unexpected 2,5‐dioxa‐3‐silabicyclo[2.1.0]pentane derivative 3. Compound 3 slowly isomerized to 2. The global reaction route mapping method of the model compounds suggests that three reaction paths from an initial silylene–ketone complex (carbonyl silaylide) to 2. A large ring strain energy of model compound for 3 (3′) (218.9 kJ·mol−1) was estimated by density functional theory calculations.

Theoretical Study of Salt Effects on the Diels–Alder Reaction of Cyclopentadiene with Methyl Vinyl Ketone Using RISM-SCF Theory

Salt effects on the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone are investigated using reference interaction site model self-consistent field (RISM-SCF) theory. The rate of the reaction is accelerated by adding LiCl to the water solvent. The structures of four transition states, endo-cis, endo-trans, exo-cis, exo-trans, were found by geometry optimization of the cyclopentadiene and methyl vinyl ketone complexes. The endo-trans structure shows the lowest energy in both water and LiCl solution. The activation barrier of the reaction in LiCl solution is lower than that in water, and the difference is in good agreement with that from experiments. The decrease in the activation barrier arises from destabilization of the reactant species. The salt effect of LiCl makes all species concerning the reaction unstable by the hydrophobic effect; however, the increased hydrophobic effect in the TS complexes is suppressed by making the hydrogen bond, which is stronger compared with the reactant methyl vinyl ketone.

Anthrone complexation with aliphatic amines in an aprotic medium

Aromatic ketone (anthrone) complexation with aliphatic amines is studied by UV-Vis, 1H, 1H-1H COSY NMR spectroscopy. It is found that the catalytic activity of aliphatic amine is observed in the reaction of anthrone oxidation by molecular oxygen in aprotic media due to the formation of intermolecular complexes consisting of two anthrone molecules and one aliphatic amine molecule.

Electrochemical Investigation of Ketone Complexation by Lewis Acids in a Chloroaluminate Ionic Liquid

A comparative study of 9-fluorenone electrochemistry in the AlCl3 : 1-ethyl-3-methylimidazolium chloride system has been carried out by addition of the Lewis acids AlCl3 and HfCl4 to fluorenone initially in the neutral melt. It has been found that each Lewis acid is capable of forming a complex with fluorenone, resulting in a positive peak potential shift for the reduction process. Neither these peak potentials, nor the colors of the complexes, are exactly the same, indicating that distinct complexes are formed for HfCl4 and AlCl3. There is some possibility of interaction of HfCl4 with the chloroaluminate melt to form the Lewis acid Al2Cl7-, but this route seems to play a minor role in the present case.