Benzene Solution Research Articles

Iron PCP Pincer Complexes in Three Oxidation States: Reversible Ligand Protonation To Afford an Fe(0) Complex with an Agostic C-H Arene Bond.

In the current investigation, the reaction of Fe2(CO)9 with the ligand precursor 2-chloro-N1,N3-bis(diisopropylphosphanyl)-N1,N3-diethylbenzene-1,3-diamine (P(C-Cl)PNEt- iPr) (1) was investigated. When a suspension of Fe2(CO)9 and 1 in CH3CN was transferred in a sealed microwave glass vial and stirred for 18 h at 110 °C the complex [Fe(PCPNEt- iPr)(CO)2Cl] (2) was obtained. In an attempt to prepare the hydride Fe(II) complex [Fe(PCPNEt- iPr)(CO)2H] (3), 2 was reacted with 1 equiv of Li[HBEt3] in THF. Instead of ligand substitution, this complex underwent a one electron reduction which led to the formation of the low-spin d7 Fe(I) complex [Fe(PCPNEt- iPr)(CO)2] (4). Exposure of a benzene solution of 4 to NO gas (1 bar) at room temperature affords the diamagnetic complex [Fe(PCPNEt- iPr)(CO)(NO)] (5). This is the first iron PCP nitrosyl complex. Protonation of 5 with HBF4·Et2O affords the cationic Fe(0) complex [Fe(κ3 P,CH,P-P(CH)PNEt- iPr)(CO)(NO)]BF4 (6) which features an η2-Caryl-H agostic bond. Even with relatively weak bases such as NEt3 the agostic C-H bond can be deprotonated with reformation of the starting material 5. Therefore, protonation of 5 is completely reversible.

Effect of Structure and Medium on Photostability of Halogenated Boron(III), Zinc(II), and Cadmium(II) Dipyrromethenates

Photostability of B(III), Zn(II), Cd(II) complexes with monoiodo- and dibromosubstituted dipyrromethenes [BF2L] and [ML2] in benzene and cyclohexane solutions is studied. It is found that the mechanism of destruction of the dyes under UV radiation is based on participation of singlet oxygen generated by the excited triplet state of the dye. Singlet oxygen enters the oxidation reactions of the pigment molecules leading to accumulation of colorless products based on di-, monopyrrol, and smaller fragments. Initial stages of the process include the reactions of dehalogenation of the dye molecules and are accompanied by enhancement of the fluorescence of the formed alkyl-substituted dipyrromethenates. The photostability of boron complexes [BF2L] is up to 32 times higher as compared to that of [ZnL2] and [CdL2]. The replacement of 4-iododipyrromethene ligands in [BF2L] and [ML2] by 5,5'-or 4,4'-dibromo-substituted ligands increases photostability of the dyes. The stability of the dyes against UV irradiation substantially decreases in benzene with respect to cyclohexane due to enhancement of polarization of the chromophore systems of dipyrromethene ligands because of their solvation with benzene (π–π-stacking).

Adsorption of 4,4'-Dithiodipyridine Axially Coordinated to Iron(II) Phthalocyanine on Au(111) as a New Strategy for Oxygen Reduction Electrocatalysis.

The coordination of PySSPy to FePc was monitored by UV/Vis spectroscopy while the adsobed FePc, anchored by PyS-Au(111), was examined by in situ STM in 0.1 M HClO4 and X-ray photoelectron spectroscopy (XPS). Rotating-disc-electrode (RDE) and linear-sweep-voltammetry (LSV) studies on the resulting FePc-modified Au(111) electrodes in an oxygen-saturated 0.1 M NaOH electrolyte exhibit excellent electrocatalytic properties for the oxygen reduction reaction (ORR), with a smaller overpotential than that observed for Au(111) with FePc deposited by direct adsorption from a benzene solution.

(Invited) Inverted Planar Perovskite Solar Cells Using Coordination Fullerene Polymers As Acceptor Layer

Perovskite solar cells can be composed of thin film of perovskite donor and fullerene derivative acceptor sandwiched between a PEDOT:PSS coated ITO positive electrode and a low work function metal negative electrode. So far, [6,6]-phenyl-C61-butrilic acid methyl ester (PC60BM) and its corresponding C70 derivative (PC70BM) have been dominantly used as the acceptors in these solar cells.1 Fullerenes and fullerene derivatives can be incorporated into polymeric structure with transition metal atoms (Pd, Pt) or metal complexes units (-Ir(CO)2-, -Rh(CF3CO2)2-, -Ni[P(CH3)3]-).2 They can be formed under chemical and electrochemical conditions. Coordination polymers of fullerene and palladium, C60Pdx (x = 1-3), have been investigated most intensively. The chemical synthesis of this material is carried out in benzene solution containing fullerene and zero-valent palladium complex as precursors for polymerization process. The same procedure has been applied for the formation of coordination polymers of fullerene derivatives, PC60BM and PC70BM. These polymers formed regularly sized spherical particles with diameter of about 120 nm (Fig. 1). They also exhibit electrochemical activity in the potential range of fullerene cage reduction (Fig. 2). Electron transfer on the polymeric backbone results in the significant increase of the conductivity of the polymeric material.3 Coordination polymers containing PC60BM and PC70BM can be used as an acceptor layer in perovskite solar cells. We anticipate an improvement in power conversion efficiency and stability of the devices in comparison to the solar cells based on tin crystalline films of PC60BM and PC70BM. Meng, L.; You, J.; Guo, T.F.; Yang, Y. Chem. Res. 2016, 49, 155-165.Balch, A.L.; Winkler, K. Chem. Rev. 2016, 116, 3812-3882.Gradzka, E.; Wysocka-Zolopa, M.; Winkler, K. Phys. Chem. C 2014, 118, 14061-14072. Figure 1

Effect of Chemical Mutagens on Chromosomal behavior of Allium cepa L

Effect of chemical mutagens was studied in mitotic cells of Allium cepa L. For this purpose root tips were treated with saturated solution of peradichloro benzene, 0.2% EMS and 0.2 % freshly prepared colchicines for 4hours to 9hours.The studies revealed a wide range of chromosomal abnormalities such as stickiness, laggards, chromosomal bridge, unequal separation, nuclear budding, multinuclear cells etc.The parentage of chromosomal abnormalities in different mitotic stages were calculated on mitotic index, frequency of phases and percentage of abnormalities in mitosis. The chromosomal abnormalities increase with increase duration of treatment. The results showed that in colchicines and EMS more than 50% abnormalities ware observed after 8 hrs of treatment, while in PDB it takes 6 hours treatment. Minimum MI was recorded as 65% in controlled cells. In colchicines and EMS treated cells 0.9.5%, 20% MI ware observed after 8hrs of treatment. Whereas in PDB maximum 23% MI was recorded in cells treated for 6hrs.

Reactivity of a Borane-Appended 1,1′-Bisphosphinoferrocene Ligand: Transition Metal and Lewis Acid Coordination, Cyclopentadienyl Ring Borylation, and Boronium Cation Generation

The reaction of a borane-appended analogue of 1,1′-bis(phosphino)ferrocene, [Fe(η5-C5H4PPh2)(η5-C5H4PtBu{(o-BPh2)C6H4})] (FcPPB), with [W(CO)6] under photochemical conditions lead to [W(CO)4(FcPPB*)] (1) (FcPPB* = [Fe(η5-C5H4PPh2){η5-C5H3P(tBu)C6H4-o-BPh}]), in which the borane has added to a cyclopentadienyl ring of the ligand backbone and benzene has been eliminated. Formation of 1 did not occur under thermal conditions, and benzene solutions of the free FcPPB ligand were unreactive under both photochemical and refluxing conditions. Boranes of greater Lewis acidity than the pendent triarylborane of FcPPB were introduced to free FcPPB in an effort to promote intramolecular electrophilic borylation of the ferrocene backbone by eliminating the borane–phosphine interaction in FcPPB. However, addition of B(C6F5)3 provided [Fe(η5-C5H4PPh2{B(C6F5)3})(η5-C5H4PtBu{C6H4(BPh2)-o})], FcPPB{B(C6F5)3} (2), in which B(C6F5)3 forms an adduct with the −PPh2 group, and the intramolecular phosphine–borane interaction pres...

Effect of solvents on optical band gap of silicon-doped graphene oxide

The objective of this study was to determine the influence on the optical band gap when the same amount of silicon-doped graphene oxide was dissolved in three different solvents namely, distilled water, benzene, and dichloroethane. Ultraviolet-visible spectroscopy was used to analyse the optical properties of the solutions. Among all these solutions distilled water containing silicon-doped graphene oxide has the smallest optical band gap of 2.9 eV and is considered a semiconductor. Other solutions are not considered as semiconductors as they have optical band gaps greater than 4 eV. It was observed that there is an increase in the value of optical band gap of distilled water, benzene, and dichloroethane solutions indicating a rise in the insulating behaviour. In this experiment, graphene oxide was synthesised from graphite powder by modified Hummer’s method and was then doped with silicon. Synthesis and doping of graphene oxide were confirmed by various characterization techniques. Fourier transmission infrared spectroscopy was used for identification of surface functional groups. X-ray diffraction was carried out to confirm the formation of crystalline graphene oxide and silicon doped graphene oxide. In x-ray diffraction pattern, shifting of intensity peak from a 2θ value of 26.5° to 10° confirmed the synthesis of graphene oxide and various intensity peaks at different values of 2θ confirmed doping of graphene oxide with silicon. Scanning electron microscopy images indicated that graphene oxide sheets were decorated with spherical silicon nanoparticles. Energy dispersive x-ray spectroscopy showed that silicon doped graphene oxide powder contained 63.36% carbon, 34.05% oxygen, and 2.6% silicon.

Ecotoxicity tests with Allium cepa to determine the efficiency of rice husk ash in the treatment of groundwater contaminated with benzene, toluene, ethylbenzene, and xylene.

The validation of adsorption treatment based on toxicity assays aims to assess the actual environmental impact caused by effluents after treatment. This study describes the use of rice husk ash as adsorbent and evaluates the efficiency of adsorption treatment to remediate groundwater contaminated with benzene, toluene, ethylbenzene, and xylene (BTEX). The synthetic effluent was prepared with standard benzene, toluene, ethylbenzene, and xylene solutions. Adsorption was assessed at treatment times 0, 60, 120, and 240min. Compounds were quantified by gas chromatography with flame ionization detector. The treatment was validated based on ecotoxicity assays using Allium cepa as indicator organism. For the treatment times stipulated, samples containing 25, 50, and 100% of BTEX were used. The dilutions were carried out with drinking water according to Fiskesjö (1985). The relative growth index (RGI), root inhibition index (Ii), and germination index (GI) confirmed the efficiency of the treatment approach tested. The best adsorption time for an initial BTEX concentration of 3.378mg/L was 60min. Critical level (EC50) and critical concentration that induced phytotoxic effect on A. cepa germination was observed only for the undiluted effluent.

New aspects in the thermochemistry of solid-liquid phase transitions of organic non-electrolytes

Thermochemistry of solid-liquid phase transitions plays an important role in solidification studies of polymers, metals, inorganic salts, and low-molecular organic compounds. Enthalpy of fusion is a source of information about intermolecular interactions in materials, crystallinity, mixtures phase diagrams shape, heat transfer in the solidification interval.The present paper is devoted to relationship between the fusion enthalpies of aromatic compounds at the melting temperature and the solution enthalpies in benzene at 298.15K. Sublimation and vaporization thermochemistry are used as an additional source of information about the latter relationship. Depending on the magnitude of deviation between the solution enthalpies in benzene at 298.15K and fusion enthalpies at the melting temperature, aromatic compounds are conventionally divided into three groups. For a large number of aromatic compounds not capable of self-association the equality between the fusion enthalpies at the melting temperature and the solution enthalpies in benzene at 298.15K is established. For self-associated aromatic compounds the solution enthalpy in benzene at 298.15K exceeds the fusion enthalpy at the melting temperature, and insertion of a substituent not forming inter- and intramolecular hydrogen bonds does not affect the difference between the solution and fusion enthalpies. The enthalpies of solution in benzene at 298.15K of several aromatic compounds not capable of self-association appear to be visibly less than the fusion enthalpies at the melting temperature. The reasons of different relationships between the fusion and solution enthalpies are analyzed using Kirchhoff's law for the fusion enthalpy.

New aspects of relationship between the enthalpies of fusion of aromatic compounds at the melting temperature and the enthalpies of solution in benzene at 298.15 K. Part II

Abstract In the present work we demonstrate how the relationship between fusion enthalpies at the melting temperature of aromatic compounds and solution enthalpy values in benzene at 298.15 K values is affected by the fusion enthalpy temperature dependence and the solution enthalpy of hypothetical liquid in benzene. The fusion enthalpies at 298.15 K were independently calculated from the solution enthalpies in benzene and the fusion enthalpies at the melting temperatures according to Kirchhoff’s law. Kirchhoff’s law was applied for fusion enthalpy adjustment calculation, assuming that the heat capacities of the aromatic compounds studied in the molten state can be extrapolated down to 298.15 K. The fusion enthalpies at 298.15 K derived from the solution calorimetry and from the fusion enthalpies at the melting temperatures are in good agreement, including the compounds with significant fusion enthalpy adjustments, demonstrating the validity of the assumptions made. The solution enthalpies of six aromatic compounds in benzene and the fusion enthalpy of dimethyl terephthalate were measured.

Dynamics of water in conical solvation shells around a benzene solute under different thermodynamic conditions.

Water molecules in different parts of the anisotropic hydration shell of an aromatic molecule experience different interactions. In the present study, we investigate the anisotropic dynamics of water molecules in different non-overlapping conical shells around a benzene solute at sub- and supercritical conditions by means of molecular dynamics simulations using both non-polarizable and polarizable models. In addition to the dynamical properties, the effects of polarizability on the hydration structure of benzene at varying thermodynamic conditions are also investigated in the current study. The presence of πH-bonding in the solvation shell is found to be an important factor that influences the anisotropic dynamics of the benzene hydration shell. The water molecules located axial to the benzene plane are found to be maximally influenced by the πH-bonding. The extent of πH-bonding is found to be somewhat reduced on inclusion of polarizability. The πH-bonded water molecules are found to reorient through large-amplitude angular jumps where the jump-angle amplitude increases at higher temperatures and lower densities. For both non-polarizable and polarizable models, it is found that the water molecules in the axial conical shells possess faster orientational and hydrogen bond dynamics compared to those in the equatorial plane. Water molecules in the axial conical shells are also found to diffuse at a faster rate than bulk molecules due to the relatively weaker benzene-water πH-bonding interactions in the axial region of the hydration shell. The residence dynamics of water molecules in different conical solvation shells around the solute is also investigated in the current study.

Особенности спектров ядерного магнитного резонанса полигидроксилированного фуллерена C-=SUB=-60-=/SUB=-(OH)-=SUB=-n-=/SUB=-

AbstractPolyhydroxylated fullerene C_60(OH)_ n (with an estimated number of hydroxyl groups n = 38–44) synthesized from pure fullerene by mixing a benzene solution of C_60 with a NaOH aqueous solution in the presence of a catalyst was studied with ^1H and ^13C solid-state nuclear magnetic resonance. Possible features of the structure of a molecule shell were revealed from ^1H NMR data. The ^13C spectrum showed a peak splitting with an increase in temperature, which is probably due to fullerenol isomers.

Adsorption and catalytic oxidation of organic pollutants using Fe-zeolite.

In this work, a natural zeolite, modified and loaded with iron (NZ-A-Fe) as a heterogeneous catalyst, was characterized for its suitability as a permeable reactive barrier (PRB) material for treatment of aromatic hydrocarbons in groundwater. Adsorption and oxidation processes were analyzed. Batch adsorption tests for benzene, toluene and xylene (BTX) aqueous concentrated solutions were performed at neutral pH. Kinetic adsorption was described with the pseudo-second-order model. Experiments were performed using a stirred batch reactor with near 11 mM initial BTX concentration applying NZ-A-Fe as solid catalyst and H2O2 as an oxidant. BTX removal reached 80% in 600 min in these experimental conditions. Catalytic oxidation was described with a pseudo-first-order kinetic model. No significant iron leaching was detected during all the experiences. These investigations show that coupling adsorption with catalytic oxidation with this novel system is a promising procedure to simultaneously remove BTX from moderately concentrated aqueous solution at neutral pH in groundwater.

Dynamics of Radical Ions of Hydroxyhexafluoroisopropyl-Substituted Benzenes.

Fluorination of resist materials is an effective method used to enhance the energy deposition of extreme ultraviolet (EUV) light in the fabrication of next-generation semiconductor devices. The dynamics of radical ions are important to understand when considering the radiation-chemistry of the resist materials using EUV and electron beam lithography. Here, the dynamics of the radical anions and cations of benzenes with one or two 2-hydroxyhexafluoroisopropyl groups (HFABs) were studied using radiolysis techniques. The formation of dimer radical cations was observed only in the monosubstituted benzene solutions of 1,2-dichloroethane. If the compound contained more than two substituents, it was found to hinder the necessary π-π overlapping. Pulse radiolysis of HFABs in tetrahydrofuran showed a characteristic spectral shift of the radical anion within the region of several hundred nanoseconds. From the results of low-temperature spectroscopy and density functional calculations, it is suggested that excess electrons of the 2-hydroxyhexafluoroisopropyl group of the radical anions cause dissociation into neutral radicals.

Bio-based mesoporous sponges of chitosan conjugated with amino acid-diketopiperazine through oil-in-water emulsions

Fully bio-based chitosan derivative was synthesized using 3-benzyl-2,5-diketopiperazine-6-acetic acid (DKP) activated by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. From IR and 1H NMR spectra, the structure of the bioconjugated chitosan and the quantitative modification were confirmed. Oil-in-water (o/w) emulsion of the obtained product was presented with the various ratios of water and benzene solution. Continuously the obtained o/w emulsions were freeze-dried to produce the mesoporous sponge, depended on the ratio of the water and benzene. These amphiphilic properties were observed by the property of the pendant DKP moieties in chitosan. The pore size in the sponges was controlled in a range from 0.1 to 0.3 μm by changing the solvent ratios.

Calculated hyperfine coupling constants for 5,5-dimethyl-1-pyrroline N-oxide radical products in water and benzene

The optimized structures of some radical adducts of 5,5-dimethyl-1-pyrroline N-oxide were computed by different methods on ESR spectra. As trapped radicals, H, N3, NH2, CH3, CCl3, OOH in water and F, OH, CF3, CH2OH, OC2H5 in benzene solutions were used. The calculated isotropic hyperfine coupling constants of all the trapped radicals were compared with the corresponding experimental data. The hyperfine coupling constant due to the β proton of the nitroxide radical was seen to be consist with the McConnel’s relation αβ = B 0 + B 1cos2θ and, to be effected with the opposite spin density of oxygen nucleus bonded to the nitrogen. It was concluded that in hyperfine calculations the DFT(B3PW91)/LanL2DZ level is superior computational quantum model relative to the used other level. Also, the study has been enriched by the computational of the optimized geometrical parameters, the hyper conjugative interaction energies, the atomic charges and spin densities for all the radical adducts.

Adsorption of Uranyl Ions in Aqueous Solutions of Maleic Anhydride-alt-Styrene Copolymers

In this study, Maleic anhydride- alt- styrene (MA/S) copolymer was synthesized in benzene solution with an initiator such as azobisisobutyronitrile by free radical copolymerization. Anhydride units are seen in resulting copolymer and anhydride units are active. By considering activities of anhydride units, adsorptions of uranyl ions in uranyl nitrate solutions with spectrophotometric method was investigated uranyl ion concentration, at different temperature and dimension of MA/S copolymer. In the adsorption investigation, Langmuır (L) type was suggested according to Giles classification system. Binding parameters such as equilibrium constant (K), monolayer coverage (n) and thermodynamic parameters such as heat of adsorption (ΔH), free energy of adsorption (ΔG) and entropy of adsorption (ΔS) for (MA/S) copolymer were calculated by using van’t Hoff and Klotz linearization methods. As a result, it can be stated that MA/S copolymer can be used as a good absorbent for uranyl from removal from waste water.

Experimental study of relaxation dynamics in solid solutions of benzene, hexa-substituted benzenes. I

The NMR study revealed that the 60° reorientational jumps in non-polar crystalline benzene do not give to a new configuration, and therefore benzene behaves as orientationally ordered system from thermodynamic perspective. All the non-polar symmetric crystalline hexa-substituted benzenes, such as hexachlorobenzene, hexamethylbenzene, etc., are supposed to be characteristically similar like benzene. We selectively probed solid solutions of these non-polar crystalline matrices with polar crystalline species employing dielectric spectroscopy, and differential scanning calorimetry. An additional process, close to Debye in nature, was observed in dielectric spectroscopy with higher activation energy, which was absent in NMR, and based on spectral behaviour we designate it as α-relaxation. Moreover, the single strong process that appears in NMR study of non-polar benzene, hexachlorobenzene, and hexamethylbenzene matrices is identical to a relatively weak process observed in dielectric spectroscopy, which we designate as secondary relaxation. In all the cases, the temperature dependence of the relaxation rates follow Arrhenius equation.

Experimental study of relaxation dynamics in solid solutions of benzene, hexa-substituted benzenes. II

In continuation with Part I of current study, we present here the orientationally disordered materials pentachloroaniline (PCA), bromopentamethylbenzene (BPMB), and their solid solutions with hexachlorobenzene (HCB) and hexamethylbenzene (HMB), respectively, encompassing the entire concentration range, studied employing dielectric spectroscopy, differential scanning calorimetry, and powder X-ray spectroscopy. The α- relaxation in these systems gets closer to Debye behaviour on non-polar rich side and is analyzed employing Havriliak-Negami equation, whereas the β- relaxation is found to be symmetric everywhere and follows Cole–Cole equation. In both the systems studied here, the temperature dependence of relaxation rates could be described by Arrhenius equation. The β- relaxation evidenced in these two binary systems appears to originate from the different microscopic mechanism that is discussed based on their spectral behaviour. Further, we probe the liquid glasses of very dilute concentrations of dipolar HSB solutes in OTP matrix, and compare it with the spectral features of the dilute dipolar solid solutions of HSBs.

Investigations of excited-state relaxation processes in 2′- hydroxychalcone analogues having pyrrole and indole moieties based on emission and transient absorption measurements

Abstract Excited-state relaxation processes of five types of 2′-hydroxychalcone (HC) analogues having naphthol, pyrrole and indole chromophores were studied based on emission and transient absorption measurements. Fluorescence with large Stokes-shifts was observed from these compounds in solution and the solid state, indicating occurrence of excited-state intramolecular hydrogen atom transfer (ESIHT) as observed for HC in solution. These fluorescent species, were, therefore, considered to be the corresponding tautomer (cis-keto form) in the excited singlet (S1) states formed via ESIHT. The fluorescence quantum yields were larger by the magnitude of one order than that of HC. Upon 400 nm laser pulsing in benzene solution of these HC analogues, no transient absorption spectra were obtained for the analogues having the phenolic moiety (Ph@Py and Ph@Ind) whereas rise and decay profiles of transient spectra were recorded independently of the amount of the dissolved oxygen for HC analogues substituted with the naphthol moiety (Np@Py, Np@Ind and Np@Np). On the analogy of the deactivation processes of HC, the obtained transient species were suggested to be the corresponding isomer of the tautomer (trans-keto form) in the ground state due to the isomerization of the excited state cis-keto form. The deactivation processes in the excited states of these compounds were discussed by considering energetic reaction diagrams for the tautomers and isomers. Replacement of the phenol moiety of HC with the naphthol was demonstrated to affect the excited state properties of the tautomer.