Reactions of benzonitrile with diiodides of neodymium, dysprosium, and thulium

The reactions of LnI₂ (Ln = Nd, Dy, Tm) with benzonitrile are accompanied by disproportionation, resulting in the formation of triiodides LnI₃(PhCN)₄ and an intractable mixture of monoiodine derivatives LnI(R)R". Hydrolysis of the mixture gives 2,4,6-triphenyl-1,3,5-tiazine, 2,3,5,6-thetraphenyl-1,4-pyrazine, and 2,4,5-triphenylimidazole. The reaction of dysprosium diiodide with acrylonitrile gives a metal-containing polymer with a molecular weight of 2700. Treatment of the polymer with water results in separation of DyI₂(OH)(H₂O) _x to give metal-free polyacrylonitrile with a molecular weight of 2400.     

Organic nanocrystals with tunable morphologies and optical properties prepared through a sonication technique

Nanocrystals with tunable morphologies and optical properties were successfully fabricated from an organic functional low-molecular-weight compound, 2,4,5-triphenylimidazole (lophine), through a sonication technique.     

Electrochemical formation and clevage of bis-imidazolyls

Bis-(2,4,5-triphenylimidazolyls) result from the dimerization of 2,4,5-triphenylimidazolyls and from the nucleophilic attack of 2,4,5-triphenylimidazole anions upon 2,4,5-triphenylimidazolylium cations. The isomeric bis-imidazolyls consist of imidazole and isoimidazole systems. Imidazoles undergo only anodic oxidation, isoimidazoles only cathodic reduction. Therefore the bis-imidazolyls may be analyzed from their electrochemical behaviour. Bis-(2,4,5-triphenylimidazolyl)-1,2′ and bis-(2,4,5-triphenylimidazolyl)-1,4′ undergo reductive bond cleavage in an ē.c?.ē. mechanism from which 2,4,5-triphenyl-imidazole anions result. The electrochemical properties of one of the bis-imidazolyls agree with that of 1,4,5-triphenyl-2-(2,4,5-triphenylisoimidazolyl-4)-imidazole and not with that of bis-(2,4,5-triphenylimidazolyl)-2,4′ as reported in literature.     

Synthesis of fluorescent diarylethenes having a 2,4,5-triphenylimidazole chromophore

Diarylethenes 1a-4a, having a fluorescent 2,4,5-triphenylimidazole chromophore in the aryl group, were synthesized. Upon excitation of the triphenylimidazole chromophore with 366 nm, 1a-4a underwent photocyclization reactions, and the solutions containing 1a-4a changed color from colorless to red-purple or to blue. The colors disappeared by irradiation with visible (lambda > 480 nm) light. The fluorescence intensity of the solutions also reversibly changed with the photochromic reactions. The fluorescence quantum yields of 1a, 2a, 3a, and 4a were determined to be 4.6, 7.7, 9.1, and 8.4%, respectively. The fluorescence quantum yields decreased with the increase in photocyclization quantum yields.     

Efficient photochemical oxetane formation from 1-methyl-2,4,5-triphenylimidazole and benzophenones

In contrast to simple imidazoles, 1-methy1–2,4,5-triphenylimidazole ($\text{1}$) produced stable oxetane photoadducts $\text{3b}$ - $\text{e}$ with good efficiency upon irradiation in the presence of benzophenone derivatives $\text{2b}$ - $\text{e}$ in acetonitrile solution. Irradiation in the solid-phase was also studied. The oxetanes $\text{3b}$ - $\text{e}$ readily underwent cycloreversion by acid catalysis or by heating.     

Microscopic phase behavior of supercritical carbon dioxide + non-ionic surfactant + water systems at elevated pressures

The microscopic phase behavior of the supercritical carbon dioxide (scCO₂) + polyethylene oxide-2,6,8-trimethyl-4-nonyl ether (TMN) + water systems at about 3 wt% of TMN were investigated using a synthetic method with a microscope. The two types of TMN (TMN-3 and TMN-10) used in this work had molecular weight distributions caused by the distribution of the number of ethylene oxide groups. Two different types of phase transition were observed when pressure was decreased gradually at a constant temperature from the high pressure at which the transparent phase was observed to the low pressure at which the separate vapor–liquid phases were observed for the scCO₂ + TMN-3 + water system at 3 wt% of TMN-3. The transparent phase was colorless under all experimental conditions and the phase transition from a transparent phase to a turbidity phase with small, dispersed droplets was observed at the higher side phase transition (higher phase transition pressure). As the pressure continued to decrease, another phase transition was observed from the phase with small droplets to a state with an accelerating aggregation of droplets (lower phase transition pressure). In the turbidity phase between the higher and the lower phase transition, the degree of turbidity became higher with decreasing pressure. On the other hand, in the phase observed below the lower phase transition, a new liquid phase adhered to the sapphire windows and the wall inside the optical cell.     

X-ray diffraction studies and phase transformations of CeNbO4+δ using in situ techniques

Investigation of CeNbO_4±δ has revealed that the previously determined phase transformations should be revised. Whereas previous studies have indicated that a reduced tetragonal modification of CeNbO₄ is produced on heating in vacuum the present study shows no evidence for this phase transformation. In contrast, a monoclinic–tetragonal phase transformation on heating in air was observed, indicating that the high temperature phase (800 °C) was a stable, oxygen excess tetragonal phase with a similar structure to the Scheelite mineral, CaWO₄. Lattice parameters for this phase were calculated to be a=5.3839(1) Å and c=11.6168(3) Å.     

Luminescence of new hydroxy-2,4,5-triarylimidazoles with an intramolecular hydrogen bond

Spectral and luminescent properties of novel derivatives of 2,4,5-triphenylimidazole synthesized in this study have been investigated in different solvents. For solutions of azomethine-substituted hydroxytriphenylimidazole (I) and two structural isomers, hydroxy-meta-bisimidazoles III and IV differing in the position of the OH group, two luminescence bands due to the presence of two ground-state conformers are observed. The equilibrium between the two conformers depends on the structure of the molecule and the solvent. For solutions of III and IV in polar and nonpolar solvents and for I in nonpolar solvents, long-wave-length luminescence dominates from the conformer with possibility of intramolecular proton transfer in the excited state. For I in protic and highly polar solvents, short-wavelength luminescence is the main one; depending on the excitation wavelength, it is possible to detect weak long-wavelength (green) or more intense short-wavelength (blue) luminescence.     

An efficient and one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by InCl3·3H2O

InCl₃·3H₂O was found to be a mild and effective catalyst for the efficient, one-pot, three component synthesis of 2,4,5-trisubstituted imidazoles at room temperature. Moreover, the utility of this protocol was further explored conveniently for the one-pot, four component synthesis of 1,2,4,5-tetrasubstituted imidazoles in high yields.     

Measurement of VLE (TPx or TPxy data) for hydrogen sulfide + (dimethylsulfide or ethylmethylsulfide or carbon disulfide) and methane solubilities in (dimethylsulfide or ethylmethylsulfide or methylmercaptan or ethylmercaptan)

VLE data (gas solubilities (TPx data) or complete TPxy data) were measured for the following systems:

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hydrogen sulfide (H₂S) + dimethylsulfide (DMS) at 278, 293, 313, and 333 K.     

One-Pot Synthesis of 2,4,5-Trisubstituted Imidazoles Using MoO3/SiO2, an Efficient and Recyclable Catalyst

A simple one-pot synthesis has been developed for the synthesis of 2,4,5-trisubstituted imidazoles using an efficient and recyclable MoO₃/SiO₂ solid acid catalyst by condensation of benzil or benzoin, benzaldehyde, and ammonium acetate in acetonitrile as a solvent. Using this solid catalyst, the reactions could be carried out under mild reaction conditions with very good yield of imidazoles, up to 95%. This catalyst could be recycled very easily, which makes this methodology environmentally benign.     

High-pressure phase behaviour of binary (CO2 + nicotine) and ternary (CO2 + nicotine + solanesol) mixtures

This work paper presents vapour–liquid equilibrium (VLE) data for binary (CO₂ + nicotine) and ternary (CO₂ + nicotine + solanesol) mixtures, at 313.2 K and 6, 8 and 15 MPa. The (CO₂ + nicotine) system exhibits three phases (L₁L₂V) in equilibrium at 8.37 MPa. It is estimated that this system most likely follows the type-III phase behaviour. In the ternary system, the presence of solanesol in the vapour phase was detected only at the pressure of 15 MPa. At this pressure, partition coefficients and separation factors for solanesol/nicotine were calculated for different initial nicotine/solanesol compositions and a strong influence of composition was found. The results were modelled using the Peng–Robinson equation of state (PR EOS) coupled with the Mathias–Klotz–Prausnitz (MKP) mixing rule (PR–MKP model). Good correlations of the binary data, particularly in the case of the (CO₂ + nicotine) mixture, were obtained. However, the model could not correlate the ternary data.     

Sensitization of photopolymer materials by halogenated derivatives of xanthene and thioxanthene dyes in the pulsed recording mode

A holographic photopolymer material based on a poly(vinyl alcohol) matrix, the acrylamide monomer, and triethanolamine as an initiator was sensitized by the xanthene dyes erythrosine; thioeryth-rosine; eosin; thioeosin; thiofluorescein, 4-iodo-, 4,5-diiodo-, and 2,4,5-triiodofluorescein; and 4-bromo-, 4,5-dibromo-, and 2,4,5-tribromothiofluorescein. The quantum yields of photobleaching of these dyes in the polymer matrix were determined. Transmission phase gratings were recorded in the pulse mode (λ = 532 nm, t _p = 10 ns). The levels of the diffraction efficiency of holograms were measured, and the 4-bromo- or 4,5-dibromothiofluorescein-triethanolamine system was found to be the most effective photoinitiator.     

Lophine derivatives as versatile analytical tools

Lophine (2,4,5-triphenylimidazole) derivatives as versatile analytical tools in biomedical sciences are described. Chemiluminescence (CL) and fluorescence (FL) properties of the lophine derivatives are first demonstrated including the CL reaction mechanism, effects of substituents on CL yields, FL spectral behaviors, etc. Next, analytical applications to the determination of metal ions such as cobalt (II) and chromium (VI) are discussed. Finally, the application studies of lophine derivatives as CL and FL reagents for the determination of organic substances in biological materials are presented. Among the derivatives, 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) are studied, with their excellent properties as labeling reagents for fatty acids and amines and/or phenols, respectively, in high-performance liquid chromatography. The utility of boronic acid derivatives as CL enhancers is also discussed in this review.     

Determination of Phenoxy Acid Pesticides in Frog and Fish Tissues by Gas Chromatography-Mass Spectrometry

A gas chromatography-mass spectrometric GC-MS method has been developed for the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in frog and fish tissues. After homogenization and sonication of 5 g samples, purification was achieved by a liquid phase extraction procedure using methyl-tert-butyl ether. The extract was reacted for 30 min at 80 °C with 10 % H₂SO₄ in methanol to form the corresponding methyl esters, which were simultaneously extracted with petroleum ether, and analysed by GC-MS in selected ion monitoring mode. Detection limits were 1.0 and 0.5 μg. kg^?1 for 2,4-D and 2,4,5-T respectively in tissue samples and the calibration curves showed good linearity (r ≥ 0.999). Twenty-five frog samples and forty-six fish samples from various regions in Korea were analyzed. 2,4,5-T was detected up to a maximum concentration of 16.2 μg kg^?1 in frogs and fish. The developed method may be valuable for the national monitoring project of endocrine disruptors (EDs) in biota.     

In Situ Tracking of Dynamic NO Capture through a Crystal-to-Crystal Transformation from a Gate-Open-Type Chain Porous Coordination Polymer to a NO-Adducted Discrete Isomer

Optimal control of gas adsorption properties in metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) remains a great challenge in the field of materials science. An efficient strategy to capture electron-acceptor-type gas molecules such as nitrogen monooxide (NO) is to use host–guest interactions by utilizing electron-donor-type MOFs/PCPs as host frameworks. Herein, we focus on a highly electron-donating chain compound by using the paddlewheel-type [Ru₂^II,II] complex [Ru₂(2,4,5-Me₃PhCO₂)₄] (2,4,5-Me₃PhCO₂⁻=2,4,5-trimethylbenzoate) with the phenazine (phz) linker: [Ru₂(2,4,5-Me₃PhCO₂)₄(phz)] ( 1 ). Compound 1 exhibited a specific gated adsorption for NO under gas pressures greater than 60 kPa at 121 K, which finally resulted in approximately seven molar equivalents being taken up at 100 kPa followed by four molar equivalents remaining under vacuum at 121 K; its Rh isomorph ( 2 ) with weaker donation ability was inactive for NO. When the sample of 1 ⊃4 NO was heated to room temperature, the compound underwent a crystal-to-crystal phase transition to give [Ru₂(2,4,5-Me₃PhCO₂)₄(NO)₂](phz) ( 1 -NO), involving a post-synthetic nitrosylation on the [Ru₂] unit, accompanied by an eventful site-exchange with phz. This drastic event, which is dependent on the NO pressure, temperature, and time, was coherently monitored by using several different in situ techniques, revealing that the stabilization of NO molecules in nanosized pores dynamically and stepwisely occurred with the support of strong electronic/magnetic host–guest interactions.     

Total synthesis of moniliformediquinone and calanquinone A as potent inhibitors for breast cancer

The first synthesis of moniliformediquinone has been achieved in which the longest linear sequence is only nine steps. The synthesis proceeds in 23% overall yield from commercially available 2,4,5-trimethoxybenzaldehyde. The key transformations include a Pd-catalyzed coupling between a phenyl triflate and an acetylene, and a TiCl₄-mediated cyclization of a benzoquinone intermediate. In addition, in vitro inhibitory effects of moniliformediquinone, denbinobin, moscatilin, and calanquinone A were determined to have IC₅₀ values of 0.7, 1.6, 2.5, and 1.5 μM, respectively.     

Separation of aromatic hydrocarbons from alkanes using ammonium ionic liquid C2NTf2 at T = 298.15 K

(Liquid + liquid) equilibrium data are presented for four ternary systems of an alkane, or aromatic compound and ethyl(2-hydroxyethyl)dimethylammonium bis{(trifluomethyl)sulfonyl}imide (C₂NTf₂) at 298.15 K: [hexane + benzene + C₂NTf₂], [hexane + p-xylene + C₂NTf₂], and [hexane, or octane + m-xylene + C₂NTf₂]. The separation of aromatic hydrocarbons (benzene, or p-xylene, or m-xylene) from aliphatic hydrocarbons (hexane, or octane) is investigated by extraction with the ammonium ionic liquid. Selectivities and distribution ratios are discussed for these mixtures at constant temperature. The data were analysed and compared to those previously reported for other ionic liquids and especially for the system {hexane + benzene + [EMIM][NTf₂]}. The nonrandom two liquid NRTL model was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems.     

Theoretical study of the triplet excited state of PtPOP and the exciplexes M-PtPOP (M = Tl, Ag) in solution and comparison with ultrafast X-ray scattering results

The [Pt₂(H₂P₂O₅)₄]⁴⁻ ions in the ground and excited states and the excited-state complexes M-[Pt₂(H₂P₂O₅)₄]³⁻ and M₂-[Pt₂(H₂P₂O₅)₄]²⁻ (M = Ag, Tl) were studied in solution with various density functional theory (DFT) functionals from Gaussian 09 and Amsterdam Density Functional (ADF) programs. Calculated results were compared with ultrafast X-ray solution scattering data. Time dependent DFT (TD-DFT) calculations with the B3PW91 functional and unrestricted open shell calculations with the mPBE functional produce good agreement with the experimental results. Compared to gas phase calculations, the surrounding solvent is found to play an important role to shorten the Pt-Pt and M-Pt (M = Ag, Tl) bond lengths, lowering the molecular orbital energies and influences the molecular orbital transitions upon excitation, which stabilizes the excited transient molecules in solution.     

Crystal chemistry of the olivine-type LixFePO4 system () between 25 and 370 °C

The crystal chemistry of two initial mixtures of LiFePO₄ and heterosite FePO₄ (0.5LiFePO₄ + 0.5FePO₄; 0.75LiFePO₄ + 0.25FePO₄) was investigated through Neutron diffraction at 350 and 370 °C, respectively, and at room temperature after cooling. At 350 and 370 °C, Li_0.5FePO₄ and Li_0.75FePO₄ are refined as olivine-type single phases, in which Li⁺ ions are disordered. Significant anisotropic microstrains, within the (001)_Pmnb planes, occur, which may be accounted for by heterogeneous distance distributions within and between the [100]_Pmnb Li⁺ channels. On cooling back to room temperature, Li_0.5FePO₄ and Li_0.75FePO₄ single phases separate into mixtures of FePO₄ + Li_0.64FePO₄ and LiFePO₄ + Li_0.64FePO₄, respectively. The Li content of this metastable intermediate phase may correspond to the occupancy of 2 out of 3 Li sites within [100]_Pmnb Li⁺ channels. In Li_0,64FePO₄, average LiO bonds are longer than in LiFePO₄, whereas FeO bond lengths are shortened, due to a fraction of Fe(III). This may be at the origin of the metastability of such intermediate phase, and thus of the two-phase mechanism between LiFePO₄ and FePO₄.