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The highly efficient solubilization of lignin in designer protic ionic compounds is reported in this work. PPhImCl provided the optimum lignin dissolution capacity and theoretical studies based on DFT calculations further confirmed that the process was energetically favored (∆E = − 13.7 kcal/mol), with strong π–π interactions and hydrogen bonding observed between the PILs and lignin.

A Sulfobetaine-based Branched Geminal Zwitterionic Liquid (SBGZL) and another one based on hydroxysultaine (HBGZL), were synthesized and their performance was evaluated in the enhancement of the oil recovery (EOR) when they are injected through flooding water into carbonate reservoirs. SBGZL obtained 39.4% and 215.5% more recovery factor for light- and heavy-oil, respectively, than obtained by a synthetic brine used as a reference; conversely, HBGZL obtained 37.5% and 44.7%, respectively. Density-Functional-Theory calculations of interaction energies reveal that both the SBGZL and HBGZL molecules adsorb on the carbonate surfaces stronger than an asphaltene molecule, implying that the good EOR performance of the zwitterionic liquids is due to the induced wettability change of the firstly-oil-wet carbonate surfaces. Keywords: Enhanced oil recovery, Density Functional Theory, Sulfobetaine-based zwitterionic geminal liquid, Supramolecular chemistry

The formation in solution of supramolecular complexes type zwitterion-cation have been shown. The industrial grade zwitterion surfactants cocamidopropyl hydroxysultaine and cocamidopropyl betaine with sodium ion were studied. A combined experimental and theoretical point of view was performed, through the use of Ultra-Performance Liquid Chromatography/Mass Spectrometry/ElectroSpray Ionization with positive mode (UPLC/MS/ESI+) analytic technique and Density Functional Theory (DFT) theoretical approach. Then, the supramolecular complex zwitterion-cation-anion triplets are shown to be viable. Mass/Charge (m/z) relationships have been determined through MS/ESI using positive mode as an ionization source, obtaining five and four molecular species for industrial grade sultaine and betaine chemical products, respectively. Also, molecular zwitterion-NaCl complexes were theoretically studied in three different dielectric constants corresponding to water, methanol, and acetone solvents. It was found that acetone, the lower dielectric constant solvent studied, shows the higher interaction energy. In both vacuum neutral, zwitterion-NaCl, and vacuum positive, zwitterion-Na+, molecular complexes the interaction of the cocamidopropyl hydroxysultaine pairs is less strong than cocamidopropyl betaine ones.

A main issue in the oil extraction and transportation is the presence of emulsions that are formed due to the physiochemical characteristics of the brine and the oil. The emulsions exhibit an increase in viscosity in comparison to the oil and it is strongly related to the water content and disperse phase morphology, this effect implies a decrease in the oil production due to oil mobility reduction, problems in the transportation, damage to the formation, among others. Experimental evidence of the properties of the emulsions for a heavy Mexican oil is presented where the disperse phase morphology directly relates with viscosity and the presence of a mechanically irreducible emulsion is confirmed. In the crude oil, the components responsible to give stability to these emulsions are mainly the asphaltenes whereas in the brines are the divalent ions, both affected by the presence of acids. In this work, a Density- Functional-Theory study was performed in order to determine the effects that the molecular structure of asphaltenes, oil acidity and calcium chloride have on the stability of water-in-oil emulsions. The aqueous environment was simulated through the Conductor-like Screening Model solvation approach. The experimental observations correlates with the conclusions which supports the idea that the presence of salts and an acidic environment promotes the increase of the viscosity and the formation of stable emulsions.

We describe the first field applications of a new multifunctional foaming agent (MFA) for production enhancement in oil wells with gas lift. The tests were conducted in three wells with water cuts from 40 to 90%, depth (>5000 m), bottomhole temperature (150°C), and brine hardness and salinity up to 180,000 ppm and 310,000 ppm TDS, respectively. The MFA was coinjected with lift gas via the annulus and generated foam downhole as it mixed with reservoir fluids in the tubing. Tested MFA concentrations ranged from 160 to 750 ppm. The field tests demonstrated that the MFA was able to increase the oil production for a fixed gas lift injection volume. The MFA also enabled to reduce lift gas consumption, while maintaining or even increasing the original oil production.

We prepared geminal zwitterionic liquids with the capability to obtain the chemical active species from laboratory to scalable production with pure or raw materials. Hence, a green-inspired and efficient process for their synthesis was developed. A performance test at reservoir conditions was conducted and it was found that the synthesized chemicals increase the oil recovery factor in an enhanced oil recovery process with properties as antiscale agents.

Unconventional crude oil as heavy, extra heavy, bitumen, tight, and shale oils will meet 10% of worldwide needs for 2035, perhaps earlier. Petroleum companies will face problems concerning crude oil extraction, production, transport, and refining, and some of these are addressed by the use of surfactants and other chemicals. For example, water-in-crude oil emulsions are frequently found during the production of mature wells where enhanced recovery techniques have been deployed. Nevertheless, the selection of adequate surfactant, dosage, type of water (sea, tap or oilfield), kind of crude oil (light, heavy, extra heavy, tight, shale, bitumen) affect the effectivity of treatment and usual bottle tests give limited information. We developed a fluorescence technique to study the effect of surfactants on medium, heavy, and extra heavy crude oil employing the natural fluorophore molecules from petroleum. We first carried out the characterization of commercial and synthetic surfactants, then dispersions of petroleum in water were studied by steady-state fluorometry and the size of petroleum aggregates were measured. The aggregation of petroleum incremented from medium to extra heavy crude oil and we discussed the effect of different surfactants on such aggregation.

Ruthenium and osmium complexes have been shown to bypass several resistance mechanisms of platinum anticancer drugs, suggesting that they might represent therapeutic alternatives. However, the resistance mechanisms that may alter the cytotoxicity of ruthenium and osmium complexes have not been identified yet. Here we investigated the mechanisms governing the variability in the cytotoxicity of two ruthenium cyclometalated compounds and their osmium equivalents. We characterized their anticancer properties in vitro and in vivo, and we developed a 4-step approach to identify genes involved in their sensibility/resistance by correlating their cytotoxicity measures with transcriptomic data of 60 cancer cell lines. As previously observed for ruthenium complexes, we showed that osmium compounds target the endoplasmic reticulum stress pathway and that their activity was not hindered by mutation in the tumor suppressor gene TP53. Then, we identified multiple sensibility/resistance genes that correlated with the cytotoxicity of cyclometalated compounds. Docking and functional studies demonstrated that inhibition of some of these resistance mechanisms, namely ABCB1 export and EGFR expression, improved the activity of cyclometalated complexes. Interestingly, switching from ruthenium to osmium favored cytotoxicity while reducing sensibility to the ABCB1 export mechanism. In summary, this study represents the first comprehensive investigation of the resistance mechanisms that alter the biological activity of ruthenium or osmium complexes, and identifies some of the chemical determinants that are important for their activity.

A zwitterionic-based chemical, the 3,3'-(octadecylamino)dipropionic acid, was quantum-theoretically designed to be applied as a corrosion inhibitor for protecting oxidized iron surfaces against the attack of very corrosive gasolines. Its performance, as well as those of worldwide-employed nitrogen-free carboxylic-diacid-based corrosion inhibitors, were experimentally evaluated and compared. Through Density-Functional-Theory calculations of the molecular interactions of the corrosion inhibitors with an iron-oxide cluster model, along with the experimental corrosion-inhibiting evaluations, it is revealed that the zwitterionic-based chemical substantially overcomes the performance of nitrogen-free chemicals. It is shown by the theoretical results that the two carboxylic heads of either, the zwitterionic-based or the nitrogen-free corrosion inhibitors, reinforce the octahedral coordination around the exposed Fe3+ atom of the iron oxide. Furthermore, when the zwitterionic-based chemical is bonded to the Fe3+ atom, a two-rings chelate is formed, in contrast to the one-ring chelate formed by the nitrogen-free corrosion inhibitors. Finally, it is theoretically predicted that oleic solvents improve the performance of the zwitterionic-based corrosion inhibitor because preclude the steric hindrance of nitrogen.

We applied the Density Functional Theory to investigate the performance of imidazoline-based corrosion inhibitors for protecting iron surfaces under aggressive environment containing O2, H2S or CO2. We found that the performance of these corrosion inhibitors correlates with their adsorption energies over the corroded surfaces, i.e., the better (worst) performance is reached under presence of CO2 (O2) because the adsorption energies are more (less) intense. Likewise, amino substituents attached to the imidazoline ring allow to form chelates with the corroded surfaces, substantially enhancing the inhibition performance. Additionally, benzene-based substituents help to the inhibition properties.

Typical adsorption isotherms show the characteristic Langmuir behavior. However, in the presence of a supramolecular surfactant, its corresponding adsorption isotherms, exhibiting atypical decrement behavior. The static adsorption results on limestone and dolomite show maximum values of 2.40 and 5.98 mgsurfactant/grock, respectively. For explaining this behavior, was developed a new modified mathematical adsorption model, ( d Г d t ) a d s = k a d s c ( Г ∞ − Г ) − k c m c ( c − c c m c ) n Г H ( c − c c m c ) . This model describes the adsorption isotherms in two regions: the first one corresponds to the conventional adsorption increase and the second to decay adsorption phenomena. This decrement behavior is mainly due to the ultra-high salinity and the monomer ⇆ micelle ⇆ vesicle equilibrium in connate water. The new model shows the better fitting with r2 = 0.9743 for limestone and r2 = 0.9668 for dolomite, respect to the Langmuir model r2 = 0.8556. Which represents the accuracy with the experimental values in the adsorption isotherm. Also, it is highlighted the significance of the information provided by the new static adsorption Langmuir mathematical model. That establishes criteria for using a chemical in enhanced oil recovery processes. From the data in the adsorption profile, the optimal concentration for the adsorption process occurs between 1800 and 2000 ppm of supramolecular surfactant. The enhanced oil recovery experiment in ultra-high salinity and hardness is better with an increase in the temperature: 8% at 80 °C, 15% at 90 °C and 20% at 100 °C.

Alkaline lignin (AkL) and sugarcane bagasse (SCB) were pretreated by an ozonification process with the aim to study its effect on the solubilization of lignin. We study the ozonification of Alkaline lignin (AkL) and sugarcane bagasse (SCB) with the aim to understand its effect on lignin solubilization and its effect on further acid and enzymatic saccharification. Here, infrared spectroscopy permitted to elucidate the structural changes on the ozonated materials. Indeed, the spectra analysis showed that AkL suffered evident oxidation after 60 min and the corresponding soluble lignin from SCB was observed within 30 min of the ozonification reaction. The total (TS) and reducing sugars (RS) produced from ozonized SCB in acid hydrolysis were 30.83 and 27.17%; while enzymatic hydrolysis resulted in 18.41 and 13.43% after 120 min of ozonation. Furthermore, there is apparently no pH effect on the solubilization of lignin and biomass saccharification. Nevertheless, the highest values of AkL, TS and RS, 0.97, 24.0 and 20.5% were obtained at pH 7, respectively. The ozone is a potential oxidizing agent to remove lignin from lignocelullosic biomass.

One of the major problems in heavy oil recovery in Mexican carbonate reservoirs is related to the formation of highly stable and viscous water-in-oil emulsions, which impacts on decreasing in hydrocarbon production. This fact is derived from the presence of high amounts of asphaltenes in the oil, as well as from the high concentrations of divalent ions in the formation water. In order to develop a technological solution for this problem, in this work a theoretical/experimental methodology is presented, which allows the development of new surfactants with multifunctional capabilities, such as changes in rock wettability, interfacial tension and emulsion breaking up. The molecular modeling is used to study emulsions formation, as well as the demulsifying capability of two kinds of surfactants: branched geminal zwitterionic liquids and new zwitterionic macrocyclic oxo-aza-crown ethers. Spontaneous-imbibition studies were carried out in order to determine the capacity of these surfactants to increase the oil recovery factor. Both theoretical and experimental parts show that the new macrocyclic surfactants presented a better performance than the branched germinal zwitterionic surfactants, therefore, they constitute a potential technological solution to increase oil recovery factor in the mentioned reservoirs. Their emulsion breaking up capacity, allows to extract oil from the porous media and avoids formation of new emulsions in the extraction process.

Theoretically, were designed and optimized by Density Functional Theory (DFT), the itaconic acid (IA), sodium vinyl sulphonate (VS) and aconitic acid (AA) singles molecules. Also, its corresponding interactions as pairs IA-VS, IA-AA and VS-AA for a better comprehension of constituents in the molecular design of the new terpolymer (labeled as PIAVSAA). Besides, the mineral scales calcium carbonate (CaCO3) and calcium sulfate (CaSO4) also were designed by computational chemistry. Attributable to the energy values obtained, PIAVSAA terpolymer promise an efficient capture of calcium ions of the scale phase better than commercial chemicals derived from acrylic acid. Experimentally, and to evaluate the anti-scale activity, were carried tests that demonstrate the capability of the new PIAVSAA to control inorganic scales problems that may become an impediment to production and avoid the plugging of the production tubing, assuring oil production.

The formation in solution of supramolecular complexes type zwitterion-cation have been shown. The industrial grade zwitterion surfactants cocamidopropyl hydroxysultaine and cocamidopropyl betaine with sodium ion were studied. A combined experimental and theoretical point of view was performed, through the use of Ultra-Performance Liquid Chromatography/Mass Spectrometry/ElectroSpray Ionization with positive mode (UPLC/MS/ESI+) analytic technique and Density Functional Theory (DFT) theoretical approach. Then, the supramolecular complex zwitterion-cation-anion triplets are shown to be viable. Mass/Charge (m/z) relationships have been determined through MS/ESI using positive mode as an ionization source, obtaining five and four molecular species for industrial grade sultaine and betaine chemical products, respectively. Also, molecular zwitterion-NaCl complexes were theoretically studied in three different dielectric constants corresponding to water, methanol, and acetone solvents. It was found that acetone, the lower dielectric constant solvent studied, shows the higher interaction energy. In both vacuum neutral, zwitterion-NaCl, and vacuum positive, zwitterion-Na

International audience; Targeting specific tumor metabolic needs represents an actively investigated therapeutic strategy to bypass tumor resistance mechanisms. In this study, we describe an original approach to impact the cancer metabolism by exploiting the redox properties of a ruthenium organometallic compound. This organometallic complex induced p53-independent cytotoxicity and reduced size and vascularization of patients-derived tumor explants that are resistant to platinum drugs. At the molecular level, the ruthenium complex altered redox enzyme activities and the intracellular redox state by increasing the NAD+/NADH ratio and ROS levels. Pathway analysis pointed to HIF-1 as a top deregulated metabolite pathway. Unlike cisplatin, treatment with the ruthenium complex decreased HIF1A protein levels and expression of HIF1A target genes. The rapid downregulation of HIF1A protein levels involved a direct interaction of the ruthenium compound with the redox enzyme PHD2, a HIF1A master regulator. HIF1A inhibition led to decreased angiogenesis in patient-derived xenografted using fragments of primary human colon tumors. Altogether, our results show that a ruthenium compound impacts metabolic pathways acting as anticancer agents in colon cancer via an original mechanism of action that affects redox enzymes differently than platinum-based drugs.

At present, many petroleum copmpanies in the world are facing processing problems about crude oil extraction, production and refining. For example, conventional pipelines are not suitable for pipelining of extra heavy oils and bitumen from the reservoirs to the refineries. According to the aforesaid, a procedure was developed for the formation of an oil-in-water emulsion employing a Mexican crude oil and its subsequent phase separation as a strategy for the pipelining of extra heavy crude oils. An O/W emulsion considerably decrease the viscosity of an extra heavy crude oil and facilitating its transport through pipelines, but crude oil must be dehydrated before further processing. We carried out a screening of commercial and synthetic surfactants for emulsion preparation as well as for breakage. The emulsion was characterized by calorimetry, optical techniques, particle size and dynamic viscosity. The stability of emulsions was evaluated by the kinetics of water separation in the presence of surfactants and heating. We also developed a factorial 2k design to study emulsion breakage with factors such as temperature, surfactant concentration and pH. All surfactants developed by ours are low toxic and full biodegradable since they atre synthesized from glucose and glycine, respectively. Thus, we developed an environmental friendly approach to facilitate crude oil transport through pipelines.

Through force spectroscopy, we use an atomic force microscope (AFM) to compare the forces between two extra heavy crude oil (EHCO) droplets. This is done in various aqueous environments in order to compare said forces in the presence of a variety of surfactants and ionic species. A crude oil droplet is attached to the AFM cantilever and pressed against other droplets placed on a substrate. Differences in the behavior of the forces as a function of surfactant chemistry, concentration and the velocity of the approach and retract of the droplets are observed for droplets with a range of diameters 10

Oil-in-water (O/W) emulsions are an innovate manner by which otherwise highly viscous heavy and extra-heavy crude oils can be transported from producing sites to transforming sites through pipelines. In spite of the important reduction in viscosity and pressure drops, water must be removed from the crude oil before further process or refining. Hence, the present study discusses the demulsification of an O/W emulsion prepared with Mexican heavy crude oil. A comparative study was carried out between microwave and oil bath heating with regard to water separation time. The effect of a chemical demulsifier and salt content of the O/W emulsion’s aqueous phase was also investigated. Microwave dielectric heating of O/W emulsions showed a greater degree of water separation in less time than conventional oil bath heating. Water separation of O/W emulsions increased with microwave power and salt content of the aqueous phase, and in the presence of a chemical demulsifier. Finally, the fluorescence emission spectra of the initial and treated O/W emulsions were in agreement with the water separation results and provide a quick and effective way to study the demulsification processes.

Alkyl-O-glucoside and -cellobioside biosurfactants were synthesized with a long fatty chain (C 8 –C 18 ) in order to prepare stable and low viscous oil-in-water (O/W) emulsions of a Mexican heavy crude oil. The resulting O/W emulsions, prepared with a single alkyl-O-glucoside or alkyl-O-cellobioside, were very unstable and broke out. Only the use of tetradecyl-O-cellobioside allowed the formation of a poor stable complex emulsion with the broader particle size distribution and more viscous than other emulsions. Nonetheless, we observed a synergistic effect when a biosurfactant mixture was used and the resulting emulsions were stable for several days while water separation occurred constantly within 40 days in static conditions. The mixture of biosurfactants with a pC 20 value higher than 4.0 and a CMC/C 20 ratio higher than 1.0 favored the formation of a less viscous, narrow particle size distribution and thermal stable O/W emulsion. This feature is remarkable important when we look for the pipeline transportation of heavy and extra-heavy crude oils as O/W emulsions. In this work, we present the characterization of biosurfactants as well as the formulation and properties of O/W emulsions of a Mexican heavy crude oil.

The Fisher glycosidation of monosaccharides ( d -glucose and d -mannose) with fatty alcohols was studied under microwave irradiation and conventional heating with strict internal temperature control using a fiber optic sensor. Surfactants were obtained in only 3 minutes under microwave at maximum power of 5 W to avoid overshoot and products decomposition. In contrast with the typical reported glycosidation methods, the reaction under conventional heating can be carried out at the same time and temperature with high conversion.

The present feature describes for the first time the application of spores from Aspergillus sp. IMPMS7 to break out crude oil-in-water emulsions (O/W). The fungal spores were isolated from marine sediments polluted with petroleum hydrocarbons. The spores exhibited the ability to destabilize different O/W emulsions prepared with medium, heavy or extra-heavy Mexican crude oils with specific gravities between 10.1 and 21.2°API. The isolated fungal spores showed a high hydrophobic power of 89.3 ± 1.9% and with 2 g of spores per liter of emulsion, the half-life for emulsion destabilization was roughly 3.5 and 0.7 h for extra-heavy and medium crude oil, respectively. Then, the kinetics of water separation and the breaking of the O/W emulsion prepared with heavy oil through a spectrofluorometric technique were studied. A decrease in the fluorescence ratio at 339 and 326 nm (I339/I326) was observed in emulsions treated with spores, which is similar to previously reported results using chemical demulsifiers.

The ferric TAML catalysts [Fe{C(6)H(2)-1,2-( NCOCMe(2)NCO)(2)CMe(2)}(OH(2))](-) (1) with counterions Na(+) (a) and PPh(4)(+) (b) function similar to horseradish peroxidase in the mediated electron transfer relays, which constitute a basis for amperometric biosensors. The mediators are mono- and bis-cyclometalated Ru and Os compounds of the type of [M(C∼N)(x)(N∼N)(3-x)](m+) with x = 1 and 2 (N∼N = 2,2'-bipyridine, (-)C∼N = 2-phenylpyridinato). Cyclic voltammograms of the Ru and Os compounds are not affected by 1a though cathodic currents increase drastically in the presence of hydrogen peroxide. The reduction potentials of [M(C∼N)(x)(N∼N)(3-x)](m+) complexes vary with both the nature of metal (Ru or Os) and the number of cyclometalated ligands x (1 or 2) and therefore the potential of working electrode can be set in the range of from -0.1 to +0.6 V versus the normal hydrogen electrode (NHE). A prototype of a biosensor for H(2)O(2) is described, in which the 1b catalyst and [Os(C∼N)(2)(N∼N)](+) mediator were coimmobilized on the surface of the glassy carbon electrode using a polymeric coating.

Cyclometalation of benzo[h]quinoline (bzqH) by [RuCl(μ-Cl)(η6-C6H6)]2 in acetonitrile occurs in a similar way to that of 2-phenylpyridine (phpyH) to afford [Ru(bzq)(MeCN)4]PF6 (3) in 52% yield. The properties of 3 containing ‘non-flexible’ benzo[h]quinoline were compared with the corresponding [Ru(phpy)(MeCN)4]PF6 (1) complex with ‘flexible’ 2-phenylpyridine. The [Ru(phpy)(MeCN)4]PF6 complex is known to react in MeCN solvent with ‘non-flexible’ diimine 1,10-phenanthroline to form [Ru(phpy)(phen)(MeCN)2]PF6, being unreactive toward ‘flexible’ 2,2′-bipyridine under the same conditions. In contrast, complex 3 reacts both with phen and bpy in MeCN to form [Ru(bzq)(LL)(MeCN)2]PF6 {LL = bpy (4) and phen (5)}. Similar reaction of 3 in methanol results in the substitution of all four MeCN ligands to form [Ru(bzq)(LL)2]PF6 {LL = bpy (6) and phen (7)}. Photosolvolysis of 4 and 5 in MeOH occurs similarly to afford [Ru(bzq)(LL)(MeCN)(MeOH)]PF6 as a major product. This contrasts with the behavior of [Ru(phpy)(LL)(MeCN)2]PF6, which lose one and two MeCN ligands for LL = bpy and phen, respectively. The results reported demonstrate a profound sensitivity of properties of octahedral compounds to the flexibility of cyclometalated ligand. Analogous to the 2-phenylpyridine counterparts, compounds 4–7 are involved in the electron exchange with reduced active site of glucose oxidase from Aspergillus niger. Structure of complexes 4 and 6 was confirmed by X-ray crystallography.

In the attempt to prepare the tris(cyclometalated) ruthenium derivative of 2-phenylpyridine, [Ru(η6-C6H6)(phpy)Cl] was treated with Hg(phpy)2. The anticipated [Ru(phpy)3]n+ species was not formed. Instead, the product of oxidative coupling of two 2-(2-pyridinyl)phenyl ligands to form octahedral [RuII(phpy)(pbp)]PF6 with pbp = 2,2′-bis(2-pyridinyl)-1,1′-biphenyl was isolated; pbp forms a nine-membered chelate with two N and two η2-C=C donor centers. The binding of η2-C=C donor units is weak as they are readily replaced by CO. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The reaction of the potentially tridentate phosphinite PCP pincer type ligand [C 6 H 4 -1,3-(OPPh 2 ) 2 ] with [( η 6 - p -cymene)RuCl 2 ] 2 affords the bimetallic species [C 6 H 4 -1,3-(OPPh 2 {Ru( η 6 - p -cymene)Cl 2 }) 2 ]. Several attempts, including the change of the ruthenium starting material (e.g. [( η 6 -benzene)RuCl 2 ] 2 ) and reflux conditions to achieve the coordination of the diphosphinite [C 6 H 4 -1,3-(OPPh 2 ) 2 ] in a tridentate PCP pincer fashion failed. Complex [C 6 H 4 -1,3-(OPPh 2 {Ru( η 6 - p -cymene)Cl 2 }) 2 ] was tested in the transfer hydrogenation of ketones.

Three cyclometalated and one coordination compounds [Os(C–N) x (bpy) 3 − x ] m ( x / m = 0/2 + ( 4 ); 1/1 + ( 3 ); 2/1 + ( 2 ); 3/0 ( 1 ); − C–N = 2-phenylpyridinato, bpy = 2,2′-bipyridine) with drastically different reduction potentials have been used for analyzing the second-order rate constants for one-electron, metal-based osmium(II) to osmium(III) oxidation of the complexes by compound I ( k 2 ) and compound II ( k 3 ) of horseradish peroxidase. Previously unknown k 2 and k 3 have been determined by digital simulation of cyclic voltammograms measured in phosphate buffer of pH 7.6 and 21 ± 1 °C. Osmium(II) species derived from osmium(III) complexes 1 and 2 were generated electrochemically in situ. Under the conditions used the reduction potentials for the Os III/II feature equal − 0.90, − 0.095, 0.23 and 0.85 V versus NHE (normal hydrogen electrode) for 1–4 , respectively. The rate constants k 2 equal ~ 5 × 10 7 , 6 × 10 8 , 2 × 10 6 and 1 × 10 5 M − 1 s − 1 and the rate constants k 3 equal ~ 9 × 10 6 , 4 × 10 7 , 1 × 10 6 and 1 × 10 5 M − 1 s − 1 for complexes 1–4 , respectively. Both rate constants k 2 and k 3 first increase with increasing the reaction driving force on going from 4 to 2 but then both decrease on going to complex 1 though the reaction driving force is the highest in this case. The system described has been explored theoretically using docking Monte Carlo simulations.

Electrochemical studies of [Os(C-N)(x)(N-N)(3-x)](m+) (1) consisting of known Os(II) species with x = 0 (a) and 1 (b) and crystallographically characterized new Os(III) bis- and tris-metalacycles with x = 2 (c) and 3 (d) (N-N = 2,2'-bipyridine, (-)C-N = 2-phenylpyridinato) revealed a Nernstian behavior in MeCN. A stepwise replacement of neutral N-N ligands by three anionic C-N donors covers a 2 V potential range from -1 to +1 V vs. Ag/AgCl for the Os(III)/Os(II) feature.

Mild electrophilic C(sp2)-H cyclometalation of 2-phenylpyridine and N,N-dimethylbenzylamine by the chloro-bridged osmium(II) dimer [OsCl(micro-Cl)(eta6-C6H6)]2 in acetonitrile affords cyclometalated pseudotetrahedral OsII complexes [Os(C approximately N)(eta6-C6H6)(NCMe)]PF6 (C approximately N=o-C6H4py-kappa C,N (2) and o-C6H4CH2NMe2-kappa C,N (5), respectively) in good to excellent yields. The cyclometalation reactions are super sensitive to the nature of an external base. Sodium hydroxide is essential for cyclometalation of 2-phenylpyridine, but NaOH retards metalation of N,N-dimethylbenzylamine, the tertiary amine being self-sufficient as a base. Further reactions of compounds 2 and 5 with 1,10-phenanthroline or 2,2'-bipyridine (N approximately N) lead to the substitution of the eta6-bound benzene to produce octahedral species [Os(C approximately N)(N approximately N)(NCMe)2]PF6 or [Os(C approximately N)(N approximately N)2]PF6 in MeCN or MeOH as solvent, respectively. The cis configuration of the MeCN ligands in [Os(C approximately N)(phen)(NCMe)2]PF6 has been confirmed by an X-ray crystallographic study. Electrochemical investigation of the octahedral osma(II)cycles by cyclic voltammetry showed a pseudoreversible MIII/II redox feature at (-50)-(+109) and 190-300 mV versus Ag/AgCl in water and MeCN, respectively. As a possible application of the compounds, a rapid electron exchange between the reduced active site of glucose oxidase enzyme from Aspergillus niger and the electrochemically generated OsIII species has been demonstrated. The corresponding second-order rate constants cover the range (0.7-4.8)x10(6) M(-1) s(-1) at 25 degrees C and pH 7.

We developed and investigated the effectiveness of new multifunctional foaming agents (MFAs) for production enhancement in oil wells with gas lift or high gas-oil ratio, high water cuts (>30%), and very high conditions of temperature (180°C), hardness (180,000 ppm), and salinity (400,000 ppm TDS). The efficiency of the MFAs was tested using two laboratory methods, which are conducted at close to wellhead and downhole conditions of temperature and pressure, respectively. These methods were used to optimize the development of the MFAs and their field application design.