Intercalation behaviour of organic derivatives of α-zirconium phosphate

The intercalation behaviour of some organic derivatives of -zirconium phosphate was investigated. Prepared organic derivatives of -zirconium phosphate can be described by the general formula Zr(RPO₃)_X(R'PO₃)_2–X. It was found that only the compound with acidic P–OH groups is able to intercalate different species while the benzene derivatives with phosphite groups do not show any intercalation properties.     

Polymethacrylate microparticles covalently functionalized with an ionic liquid for solid-phase extraction of fluoroquinolone antibiotics

Microparticles were synthesized by suspension copolymerization of the synthetic ionic liquid (IL) 1-allyl-3-methyl-imidazolium bromide with ethylene glycol dimethacrylate. The particles have a regular spherical shape and an average diameter of 65 ± 24 μm. Their affinity for the fluoroquinolone antibiotics ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) is much higher than that of the blank polymer (not containing an IL), of polymers using methacrylic acid as functional monomer, of hydrophilic-lipophilic balanced sorbents, and of C₁₈ sorbents. The microparticles were applied to the solid-phase extraction and rapid preconcentration of the fluoroquinolones from urine which then were quantified by HPLC. The calibration plot covers the 0.05 to 20 μg mL⁻¹ concentration range, and the average recoveries at three spiking levels range from 93.6 to 103.7 %, with RSD of ≤5.7 %. The method was successfully applied to the determination of fluoroquinolones in spiked urine.

Microparticles covalently functionalized with an ionic liquid ([Amim][Br]) were synthesized by suspension copolymerization and show higher affinity for fluoroquinolones than other sorbents. The microparticles were used as a sorbent for solid-phase extraction and preconcentration of three fluoroquinolones from urine.

     

Evaluation of chemiluminescence reagents for selective detection of reactive oxygen species

In order to evaluate the chemiluminescence (CL) reagents for selective detection of reactive oxygen species (ROS), we comprehensively measured the CL responses of 20 CL reagents (three luminol derivatives, two imidazopyrazinone derivatives, eight lophine derivatives, six acridinium ester derivatives and lucigenin) against six types of ROS (superoxide anion: O₂⁻, hydroxyl radical: OH, hydrogen peroxide: H₂O₂, hypochlorite anion: ClO⁻, singlet oxygen: ¹O₂, and nitric oxide: NO). As a result of the screening, it was found that nine CL reagents selectively detected O₂⁻ while one CL reagent selectively detected OH. However, no CL reagent had selectivity on the detection of H₂O₂, ClO⁻, ¹O₂ and NO. Our screening results could help to select the most suitable CL reagent for selective determination of different ROS.As an application study, 4-methoxyphenyl-10-methylacridinium-9-carboxylate (MMAC), one of the acridinium ester derivatives, showed high selectivity on the detection of O₂⁻, and thus was applied to the assay of superoxide dismutase (SOD) activity. The dynamic range and detection limit of the developed CL assay were 0.1-10 and 0.06 U mL⁻¹, respectively. Significant correlation (r = 0.997) was observed between the results by the CL assay using MMAC and the spectrophotometric assay using 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt.     

Electrochemical and solid-phase synthetic modification of glassy carbon electrodes with dihydroxybenzene compounds and the electrocatalytic oxidation of NADH

We report the preparation, using electrochemical and solid-phase synthesis, and characterisation of a 26 member library of 13 dihydroxybenzene derivatives covalently attached to glassy carbon through ethylenediamine (EDA) and C₆H₄CH₂NH linkers. First, Boc-protected EDA or Boc–NHCH₂C₆H₄ were electrochemically attached to the GC surface. After Boc-deprotection, dimethoxybenzoyl chlorides were coupled to the EDA and C₆H₄CH₂NH linkers using solid-phase synthesis followed by deprotection of the methoxy groups to give the corresponding dihydroxybenzene compounds. Surface coverage and electrochemical parameters of the dihydroxybenzene modified electrodes were evaluated in parallel using cyclic voltammetry. The mid-peak potentials, E_mp, and surface coverages for the 13 dihydroxybenzene derivatives were found to be independent of the choice of linker. The mid-peak potentials of the immobilised dihydroxybenzene derivatives varied between 0.0 and 260 mV vs. SCE and their surface coverages varied between 0.07 and 1.1 nmol cm^− 2, depending on the pattern of substitution of the dihydroxybenzene ring. The electrocatalytic activities of the library were evaluated for mediation of NADH oxidation, and the ortho-dihydroxybenzene derivatives were found to have higher catalytic activity.     

Study of the carbonyl products of terpene/OH radical reactions: detection of the 2,4-DNPH derivatives by HPLC-MS

The oxidation of the terpenes - and -pinene, limonene and ³-carene by hydroxyl radicals has been investigated in a fast-flow reactor coupled to a liquid nitrogen trap for collecting the carbonyl compounds. Identification of the products was performed via 2,4-dinitrophenylhydrazone (DNPH) derivatization of the carbonyls to form the mono- and di-DNPH derivatives, which were analysed by high-performance liquid chromatographic (HPLC)-DAD (diode array detector) and HPLC-mass spectrometry (HPLC-MS). Both electrospray ionization [ESI(–)] and atmospheric pressure chemical ionization [APCI(–)] were suitable for the detection of the DNPH derivatives of formaldehyde, acetaldehyde, myrtanal, campholene aldehyde, perillaldehyde, acetone, nopinone, trans-4-hydroxynopinone and 4-acetyl-1-methylcyclohexene. Also the mono-DNPH derivatives of the dicarbonyl compounds pinonaldehyde, endolim and caronaldehyde could be identified. The MS² spectra generated in the ion trap of the mass spectrometer allowed us to distinguish between aldehydes and ketones on the basis of the characteristic fragment ion m/z 163 for the aldehydes. For the quantitative analysis of the mono-DNPH derivatives, ESI(–) in combination with single ion monitoring (SIM) detection showed the lowest detection limits. For the quantification of the dicarbonyl compounds, the acid-sensitive di-DNPH derivatives had to be formed by keeping the acidity in the acid-catalysed derivatization reaction at about 1.7 mM H₂SO₄. Detection of these dicarbonyl compounds can only be performed by APCI(–) with somewhat lesser sensitivity than by HPLC-DAD.     

Iodine-promoted imino-Diels-Alder reaction of fluorinated imine with enol ether: synthesis of 2-perfluorophenyl tetrahydroquinoline derivatives

Iodine was used to catalyze the hetero-Diels-Alder reaction of pentafluorobenzylidineaniline (C₆F₅CHNAr 1) with enol ethers to afford the corresponding tetrahydroquinolines derivatives as a mixture of cis/trans stereoisomers in moderate yields. These products could also be prepared by one-pot, three-component reaction of pentafluorophenylaldehyde, anilines, and enol ethers under the same reaction condition. Mild and neutral reaction conditions, facile experimental procedure, and low price of iodine should make this method attractive for practical synthesis of many fluorinated tetrahydroquinoline derivatives.     

Synthesis of organic molecules from functionalized alkynes and metal carbonyls. Reaction pathways and intermediates. Crystal structure of Fe3(CO)6(μ-CO)2[(HC ≡ CCMe2)2NH]

The reactions of VIII Group metal carbonyls with dipropargylamines and other functionalized alkynes lead to new cluster and binuclear compounds: the ruthenium cluster derivatives may be considered as models of intermediates proposed in metal-mediated organic syntheses. The iron and cobalt carbonyls give metallacyclic derivatives which are intermediates in organic syntheses. The structure of Fe₃(CO)₆(-CO)₂[(HC CCMe₂)₂NH] has been determined by an X-ray diffraction study.     

Magnetochemistry of boron hydride structures. Empirical aspects

The reviews and monographs on magnetochemistry of boron compounds are discussed. The structural peculiarities of borane derivatives relevant to magnetochemical calculations of diamagnetic contributions are are considered. Experimental measurements of diamagnetic susceptibility for deltahedral B₁₀H ₁₀ ^2– and B₁₂H ₁₂ ^2– cluster closo-anions were used to derive the diamagnetic atomic increments of the B atoms (_B) with coordination numbers 5 and 6. The atomic increments _B thus obtained were used to calculate molecular diamagnetic susceptibility _M of borane derivatives. Diamagnetic susceptibility _M was measured and calculated for the series of borane derivatives B_nH _n ^2– and B₁₀H₁₂L₂ (L is a Lewis base)and cobalt(III) derivatives of ortho-carborane(12) [(B₉C₂H₁₁)₂Co_n(B₈C₂H₁₀) _n–1] ^n–. Diamagnetic increments were obtained for |B₁₀H₁₂| fragments and (B₉C₂H₁₁)^2– and (B₈C₂H₁₀)^4– ligands. The increments can be employed for calculating _M for novel compounds. The calculated values of _M coincide with the experimental values within 2%–6%.Original Russian Text Copyright © 2004 by V. V. Volkov and V. N. IkorskiiTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 729–740, July–August 2004.This revised version was published online in April 2005 with a corrected cover date.     

Determination of the threo- and erythro- configurations of vicinal diastereomeric derivatives of higher fatty acids with the aid of PMR spectra

Conclusions The PMR spectra of vicinal diastereomeric dihydroxy-, acetoxyhydroxy-, and halohydroxyoctadecanoic and -docosanoic acids and their trimethylsilyl derivatives have been considered. It has been shown that the signals of the methine protons of the erythro isomers appear at lower fields than those of the threo isomers. On passing from the dihydroxy, acetoxyhydroxy, and halohydroxy acids to their TMS derivatives, the signal of the methine proton shifts down-field, and = CHOSi (CH₃)₃ — CHOH is greater for the threo form than for the erythro form, The difference in the chemical shifts of the vicinal methine protons of the dihydroxy, acetoxyhydroxy, and halohydroxy acids and their TMS derivatives can be used to determine the threo and erythro configurations of the corresponding diastereometric derivatives of higher fatty acids.A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 299–305, May–June, 1978.     

Generalization of analytic energy derivatives for configuration interaction wave functions

This paper takes the form of a review including some original contributions. A fresh derivation of analytic energy derivative expressions for configuration interaction (CI) wave functions is presented. In this method the CI energy is described by _IJC_IC_J(H _IJ-_IJE) so that the orthonormality condition is explicitly included therein. In the sequence of differentiations up to fourth order it will be demonstrated that each derivative may be expressed in terms of (H _IJ-_IJE) and its derivatives in a symmetric way with respect to the interchange of differential variables. In a similar manner, the CI variational condition may be described in an equation which explicitly includes the normalization condition. It is shown that the differentiation of the modified variational condition produces the coupled perturbed configuration interaction (CPCI) equations in directly soluble and compact forms. The necessary formulae for the energy derivatives up to fourth order and the CPCI equations up to second order are explicitly given.     

A comparative study of trace enrichment of chlorophenols in water by extraction with C6 and C8 alkanes and by C18 reversed-phase adsorption

The efficiency, reproducibility and sensitivity ofn-hexane and iso-octane extraction and of C₁₈ reversed-phase adsorption for accumulation of 4-chloro-, 2,4-dichloro-, 2,4,5- and 2,4,6-trichloro-, 2,3,4,6-tetrachloro- and pentachlorophenol from aqueous solutions were compared. In extraction procedures the acetyl and pentafluorobenzoyl derivatives of chlorophenols were extracted from water. In adsorption procedure chlorophenols adsorbed on a Sep-Pak C₁₈ cartridge were eluted with acetone and after that derivatized analogously.All three procedures were found to be applicable for an efficient trace enrichment of chlorophenols in water, the proper choice being dependent on the required sensitivity of the analysis. Lower detection limits of single compounds at 10 ng·1^–1 levels were achieved by adsorption procedure owing to the more uniform and for most chlorophenols higher adsorption than extraction recoveries as well as owing to the possibility of treating larger volumes of water samples. The extraction procedure could be successfully applied to the concentrations of chlorophenols in water 1g·1^–1.Owing to its higher efficiency and better sensitivity the C₁₈ reversed-phase adsorption procedure was chosen as the more suitable one for the determination of chlorophenol levels in surface, ground and drinking waters. The conversion of chlorophenols accumulated from a water sample parallel to both acetyl and pentafluorobenzoyl derivatives and the analysis of both types of derivatives on two basically different gas Chromatographic columns were recommended for a more reliable identification and quantitation of the compounds analyzed.     

Protonation of acetyl and formyl derivatives of pyrrole

By electronic spectroscopy and PMR spectroscopy it has been shown that the protonation of derivatives of - and -acetylpyrroles and the corresponding formylpyrroles in 14–26 N H₂SO₄ takes place at the oxygen atom of the carbonyl group. The derivatives substituted by an alkyl group (CH₃, C₂H₅) in position 4 have a similar structure of the conjugate acids in concentrated H₂SO₄. Under the same conditions, the derivatives not substituted in position 4 are capable of adding a proton to C₄ of the pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1498–1504, November, 1973.     

2,2′-biimidazole, 2,2′-bibenzimidazole and imidazoles as ligands in cationic rhodium(I) complexes

Summary Cationic rhodium(I) complexes of the type [Rh(diolefin)(L-L)]ClO₄ and [Rh(diolefin)L₂]ClO₄, (diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene and tetrafluorobenzobarrelene; L-L = 2,2-biimidazole, 2,2-bibenzimidazole; L = pyrazole or imidazoles) are described. [Rh(CO)₂(L-L)]-C1O₄ complexes, which can be obtained by reaction of cyclooctadiene derivatives with CO, react with P-donor ligands in equimolar ratios to yield [Rh(CO)(P-donor)(L-L)]ClO₄ monocarbonyl derivatives. The catalytic activity of some of these complexes is considered.     

Theoretical Investigation of Second-Order Nonlinear Optical Properties of Substituted Benzothiazole Derivatives

On the basis of the ZINDO program, we have designed a program to calculate the nonlinear second-order polarizabilities _ijk, ₀, and according to the SOS expression. The second-order nonlinear optical properties of a series of benzothiazole derivatives including 2-(p-donor--styryl)-6-nitrobenzothiazole, 2-(p-donor-phenyl)-azo-6-nitrobenzothiazole, and 2-(p-nitro--styryl)-6-donor-benzothiazole derivatives were studied. The calculated results show that when the benzothiazole rings are connected to the nitro group (acceptor), the values are relatively larger. This does not agree with the theory of auxiliary donor–acceptor effects. The 2-(p-donor--styryl)-6-nitrobenzothiazole derivatives exhibit more nonlinearity than 2-(p-donor-phenyl)-azo-6-nitrobenzothiazole derivatives. The 2-(p-donor--styryl)-6-nitrobenzothiazole derivatives are good candidates as chromophores due to their high nonlinearities and good thermal stability.     

Reaction of electron deficient NN bonds with acyloxyketenes and mesoionic 1,3-dioxolium-4-olates: fast equilibrium between acyloxyketenes and mesoionic 1,3-dioxolium-4-olates

Reaction of azodicarboxylates with acyloxyketenes arising from dehydrochlorination of acyloxyphenylacetyl chlorides was carried out to give triacylamidine derivatives in good yields. The same triacylamidine derivatives were also obtained in good yields from the reaction with mesoionic 1,3-dioxolium-4-olates generated by Rh₂(OAc)₄-catalyzed decomposition of phenyldiazoacetic anhydride derivatives. Formation of the same compounds from different starting materials is explained by 1,3-dipolar addition between electron deficient NN bonds and mesoionic 1,3-dioxolium-4-olates, indicating fast equilibrium between acyloxyketenes and mesoionic 1,3-dioxolium-4-olates.     

Heterocyclic nitro compounds

The acidity of a number of nitro derivatives of 1,2,4-triazole has been determined. The acidity indices correlate well with Hammett's _I and _meta constants and somewhat less well with the _para constants. The high values of show the great sensitivity of the system to the influence of substituents. The acidities of the conjugate acids of 3-nitro-1,2,4-triazole and its C- and N-methyl derivatives have also been determined. Hammett's postulate is not observed for these compounds, and the amide scale of acidity, H_A, is more suitable for calculating their acidity indices than H_O.For part III, see [1].     

Synthesis and characterization of cyclopentadienyl transition metal halides,part I,vanadium halides

Summary Reactions between -Cp₂V and PX₃ (X=Cl, Br or I) yield the corresponding dihalogenated derivatives -Cp₂VX₂ (X=Cl, Br or I). The oxidative addition of ICl and IBr to -Cp₂V gives mixed halogenated derivatives -Cp₂VIX (X=Cl or Br). All the compounds have been characterized by elemental analyses, magnetic moment measurements and i.r. and e.p.r. spectra.     

Novel addition in trifluoromethylation of [70]fullerene

Pyrolytic trifluoromethylation of [70]fullerene with CF₃CO₂Ag at 300 °C results in the addition of up to 12 CF₃ groups to the fullerene cage. Forty-six C₇₀(CF₃)_n derivatives (numbers in parentheses) were separated by two-stage high pressure liquid chromatography (HPLC) as follows: n = 2(2), 4(16), 6(9), 8(14) 10(5), some being characterised by NMR. The range of derivatives is much greater than for other [70]fullerene reactions, and as with [60]fullerene trifluoromethylation, no single derivative is dominant, indicating that kinetic stability mainly controls product formation. NMR spectra show most derivatives to be unsymmetrical, with combinations of quartets and septets (overlapping quartets) due to contiguous (‘linear’) addend arrays, having significantly different coupling constants of the ‘terminal’ quartets of between 9.1 and 17.7 Hz. These differences, together with those observed previously in trifluoromethylation of [60]fullerene are consistent with addition across both 6:6- and 5:6-ring junctions. Of the two C₇₀(CF₃)₂ isomers, one has either C_s or C₂ symmetry, the other has C₁ symmetry, whilst the C₇₀(CF₃)₄ derivatives fall into four categories: (i) symmetrical compounds (one gives only two singlets in the NMR); (ii) unsymmetrical compounds that show a ‘linear’ coupling sequence; (iii) unsymmetrical compounds having a remote pairs of adjacent groups; (iv) compounds having a coupled array of three CF₃ groups, together with a remote group suggesting sterically-driven migration. The first evaluation of differential NMR couplings across 6:6- and 5:6-bonds in a fullerene has been made using C₆₀F₆ as a model.     

Substituent Effects on the Driving Force for Inclusion Complexation of α- and β-Cyclodextrin with Monosubstituted Benzene Derivatives

The association constant values, K_a, for the inclusion of - and -CD with monosubstituted benzene derivatives were determined by means of UV-vis and fluorescence spectroscopy. The stability of the complexes is influenced by the properties of the substituents of the guest compounds. Regression analysis was used to create a set of inclusion models with the experimental association constant ln K_a and the corresponding substituent molar refraction R_m, hydrophobic constant and Hammett constant of the benzene derivatives. The ln K_a value mainly correlated with R_m for -CD and with both R_m and for -CD complexes. The association constants predicted by the models are in good agreement with the experimentally determined data. This suggests that the inclusion complexation of benzene derivatives with -CD is predominantly driven by van der Waals force and with -CD mainly by van der Waals force and hydrophobic interactions.     

Hydrogen bonding and molecular association in methylated 3-hydroxypyridines

Association in derivatives of 3-hydroxypyridine has been examined via the chemical shifts for OH in PMR for equimolar mixtures of the derivatives of pyridine and phenol in CCl₄ and CH₂Cl₂. It is found that spatial screening of the pyridine N and phenol OH by methyl groups has an anomalous effect on the strength of the complex. A possible explanation is that the ionic form NH . . . O is stabilized on account of increased basicity of the N and acidity of the H in the methyl derivatives of pyridine and phenol. Domination by the intermolecular hydrogen bond between OH and N is the distinctive feature of association in 3-hydroxypyridines relative to association in phenol. The temperature dependence of _OH gives the enthalpy and entropy of association for 2, 4, 6-trimethyl-3-hydroxypyridine and of complex formation for various model systems. IR measurements confirm the conclusions.See [1] for the previous communication.We are indebted to G. G. Dvoryantseva for making the IR measurements.