Dimethyl Sulphoxide Medium Research Articles

BIOLOGICAL ACTIVITY CALCULATED BY THE PASS METHOD AND EXPERIMENTAL ASSESSMENT OF THE ACIDITY OF NH GROUPS IN SULPHONAMIDE POLYCHLOROETHYLATED ARENES AND GLYCINE DERIVATIVES IN DIMETHYL SULPHOXIDE MEDIUM

The acidity of NH-groups of a number of sulphonamides and glycine derivatives in a dimethyl sulphoxide medium has been investigated using the potentiometric method. Dissociation constants of these compounds are determined from titration curves. It is shown that the acidity of NH groups in the studied sulphonamides is controlled by the polar effect of substituents. The possibility of quantitative potentiometric analysis of glycine derivatives has been established for the first time. Biological activity has been predicted with the help of PASS software. The correlation of NH group acidity with the biological potential of the compounds has been established.

Probing Molecular Chirality on the Self-Assembly and Gelation of Naphthalimide-Conjugated Dipeptides.

In this work, 1,8-naphthalimide (NMI)-conjugated three hybrid dipeptides constituted of a β-amino acid and an α-amino acid have been designed, synthesized, and purified. Here, in the design, the chirality of the α-amino acid was varied to study the effect of molecular chirality on the supramolecular assembly. Self-assembly and gelation of three NMI conjugates were studied in mixed solvent systems [water and dimethyl sulphoxide (DMSO)]. Interestingly, chiral NMI derivatives [NMI-βAla-lVal-OMe (NLV) and NMI-βAla-dVal-OMe (NDV)] formed self-supported gels, while the achiral NMI derivative [NMI-βAla-Aib-OMe, (NAA)] failed to form any kind of gel at 1 mM concentration and in a mixed solvent (70% water in DMSO medium). Self-assembly processes were thoroughly investigated using UV-vis spectroscopy, nuclear magnetic resonance (NMR), fluorescence, and circular dichroism (CD) spectroscopy. A J-type molecular assembly was observed in the mixed solvent system. The CD study indicated the formation of chiral assembled structures for NLV and NDV, which were mirror images of one another, and the self-assembled state by NAA was CD-silent. The nanoscale morphology of the three derivatives was studied using scanning electron microscopy (SEM). In the case of NLV and NDV, left- and right-handed fibrilar morphologies were observed, respectively. In contrast, a flake-like morphology was noticed for NAA. The DFT study indicated that the chirality of the α-amino acid influenced the orientation of π-π stacking interactions of naphthalimide units in the self-assembled structure that in turn regulated the helicity. This is a unique work where molecular chirality controls the nanoscale assembly as well as the macroscopic self-assembled state.

Studies of Phenol Electrooxidation Performed on Platinum Electrode in Dimethyl Sulphoxide Medium. Determination of Unreacted Phenol by the Effect of 4‐Vinylbenzenesulphonate on the Electrooxidation Process

AbstractThe electrooxidation of phenol was studied in the presence of sodium 4‐vinylbenzenesulfonate in various quantities. When the sulphonate was dissolved in equal or higher quantities than phenol the peak currents increased gradually and suppression of electropolymerization was observed. When the sulphonate quantity was smaller than that of phenol brown films fouled the electrode. The observed phenomenon was utilized in an analytical procedure namely determination of unreacted phenol in electrolysis solution with linear dynamic range between 0 and 50 mM and 2.96 mM detection limit. The shape of curve became saturated‐like above 50 mM.

Acid-base properties of imidazo[2,1-<i>b</i>] tiazole and tiazolo[3,2-<i> а</i>] benzimidazole derivatives

For over 30 years, azomethine groups have been attracting significant research interest due to their high electrophilicity formed under the influence of strong electrophilic substituents. The combination of a polyhalidealkyl group and functional substitutes in close proximity to the azomethine bond reveals a wide range of possible chemical transformations, one of which is the production of heterocyclic derivatives. Since heterocyclic compounds are of interest in terms of their medical and synthetic prospects, research into the NH-acidity of these compounds is highly relevant. Information on the acid-base properties of such compounds is useful for predicting their reactivity and physical-chemical properties. The potentiometric titration method was used to determine the dissociation constants of the substances under study. As a result, titration curves with a different number of dissociation stages (their number was determined by the number of NH-groups) were obtained, which showed a clear jump in the potential of the indicating electrode. The experimental determination of the acid-base behaviour of the synthesized sulphonylamine-substituted imidazo[2,1-b]tiazoles and thiazolo[3,2-a]benzimidazoles was carried out in dimethylsulphoxide medium. The semi-neutralization potentials were determined using titration curves. A relationship between acidity constants (pK A ) and semi-neutralization potentials was determined. The pK A =f (E 1/2 ) dependence allows the constants of NH-acidity for newly synthesized compounds in dimethylsulphoxide medium to be predicted. The statistical range of the conducted potentiometric titration was determined. The obtained dissociation constants showed a high level of intermediate precision. The variation coefficients ranged from 0.34 to 1.48%. The PASS software was used to calculate the potential of biological activity (Pa) of the compounds under study. The relationship between NH-acidity and biological potential is still ambiguous.

Preliminary investigation of the effects of an FCF inhibitor interference with Septin in the early stage embryos in mice.

The objective of the present study was to investigate the effects of for chlorfenuron (FCF) interference with the septin protein on early stage embryos in mice. The 1‑cell embryos were collected and divided into an FCF interference group and a control group. The FCF interference group was cultured in FCF media and the control group was cultured in dimethyl sulphoxide media at 37˚C with 5% CO2 until the desired phase was achieved. Septin2 protein expression was detected using immunofluorescence and western blot analysis. Blastocyst α‑tubulin was stained by immunofluorescence to observe the alterations in spindles and microtubules. The rate of early embryo development into blastocysts was significantly reduced following FCF treatment (P<0.05). In the control group, septin2 was observed with a confocal microscope; septin2 was expressed in embryos at all stages and mainly in the blastomeres from the 2‑cell stage onwards, with the expression concentrated in the nuclei of the blastomeres as identified by strong fluorescence. In the FCF interference group, septin2 was weakly expressed in the nuclei of blastomeres at the 2‑ and 4‑cell stages, and in the granulated blastomeres at the 4‑ and 8‑cell stages. Expression was barely observed in and following the morula. Granulation was observed starting from the 4‑ and 8‑cell stages. Compared with the control group, the FCF interference group exhibited irregular microtubules, abnormal spindle morphology and disordered chromosome arrangement in the blastocysts. The septin2 protein was expressed throughout the early stage embryo from the 2‑cell stage to the blastocyst and localized in the nuclei of blastomeres. When the septin protein experienced interference by the FCF inhibitor, septin2 protein expression was reduced, which simultaneously resulted in abnormal embryonic development, uneven cytoplasmic division, various sizes and a reduced number of blastomeres, granulation in the blastomeres, disordered blastocyst microtubule distribution, spindle shape alterations and an abnormality of chromosome arrangement.

Взаимодействие гидрата 1-герматранола со щавелевой кислотой

Polycarboxylic acids are involved in many life processes, along with germatranes exhibiting high biological activity. At the same time, the studies on the reactions of 1-substituted germatranes with polycarboxylic acids appear to be insufficient. On the one hand, compounds of germatranes with substances containing a car boxyl group were reported to be stable in the presence of water. On the other hand, the germatranic cycle of 1-germatranol hydrate in an aqueous medium is acknowledged to be decomposed by D-tartaric acid to bis(µ-tartrato)di(hydroxy)germanate(IV) triethanolammonium form. In this work, the interaction of 1-germatranol hydrate (H 2 O·НОGe(OCH 2 CH 2 ) 3 N) with oxalic acid (HOC(O)COOH) in water, dimethyl sulphoxide and acetonitrile alcohol was studied. The reaction in an aqueous medium at 20–25 °С quickly leads to the cleavage of the germatrane skeleton followed by the formation of [(C 2 O 4 )2Ge(OH) 2 ] 2- ·H + ·[(HOCH 2 CH 2 ) 3 NH] + bis(oxalate-O,O') dihydroxygermanate triethanolammonium. As a result of the topochemical reaction, exposing the reaction residue following evaporation of water at 50 °С in a vacuum of 2 mm Hg for 2 h subsequently leads to the formation of (ROC(O)COOGe(OCH 2 CH 2 ) 3 N(R=H) and N(CH 2 CH 2 O) 3 Ge mono- and bis(germatran-1-yl)oxalate), as well as to the reduction of 1-germatranol. Under additional exposure of the reaction mixture in a 2 mm Hg vacuum at 100 °C for 40 min, O[Ge(OCH 2 CH2) 3 N] 2 bis(germatran-1-yl)oxide and (germatran-1-yl)formate is formed. Following the water dissolution of the reaction mixtures, the resulting compounds undergo another conversion to bis(oxalate-O,O')dihydroxygermanate triethanolammonium and 1-germatranol. Heating a mixture of 1-germatranol hydrate with oxalic acid in a dimethyl sulphoxide and acetonitrile medium along with 1-germatranyl oxalates leads to the formation of a hydrolytic cleavage product of the germatrane skeleton, bis(oxalate-O,O')dihydroxygermanate triethanolammonium, while the boiling of isoamyl alcohol mainly provides for the esterification reaction with a 1-isoamyloxygermatrane yield exceeding 90 %.

Dimethyl sulphoxide and electrolyte-free medium improve exogenous DNA uptake in mouse sperm and subsequently gene expression in the embryo.

SummaryOne of the methods to generate transgenic animals is called sperm-mediated gene transfer (SMGT). Mature sperm cells can take up exogenous DNA molecules intrinsically and transfer them into the oocyte during fertilization. This study assessed the effect of dimethyl sulfoxide (DMSO) and electrolyte-free medium (EFM) on DNA uptake (EGFP-N1plasmid) in mouse sperm. Sperms cells cultured in human tubular fluid (HTF) without any treatment were considered as the control group. Sperms cells that were incubated in EFM and HTF with DNA/DMSO at 4°C were classified into EFM and HTF groups. Sperm motility and viability were assessed following treatment. In vitro fertilization (IVF) with sperm in all groups was performed. Fertilization, embryo development and GFP-positive blastocyst rates were analyzed and compared. The result showed that sperm motility and viability in EFM were better than those in the HTF group. The rate of development to reach the blastocyst stage and GFP-positive blastocysts was significantly higher in the EFM group compared with the HTF group (P<0.05). Our data demonstrate that sperm stored in the EFM group can improve the efficiency of SMGT for the generation of GFP-positive blastocysts.

Synthesis and characterisation of a high dielectric constant and ac-conducting PANI/[Co(NH3)3(C4H4N2)3]Cl3 nanocomposite

In this study we have synthesised polyaniline/[Co(NH3)3(C4H4N2)3]Cl3 nanocomposite by in-situ chemical polymerisation method in non-aqueous dimethyl sulphoxide medium. The filler photoadduct was synthesised by irradiating aqueous solution mixture of hexaminecobalt(III) chloride metal complex and pyrazine, which was subsequently reduced in size by high energy ball milling prior to incorporation into the polyaniline matrix. The optical, structural, thermal and dielectric properties of the as synthesised nanocomposite were studied. The energy band gap as obtained from Tauc plot was observed higher for nanocomposite as compared to polyaniline. FTIR and XRD results show presence of photoadduct nanoparticles in the polyaniline matrix and successful interactions between them. The crystallite size as obtained from XRD confirms the nano dimensions of both photoadduct (26 nm) and nanocomposite (18 nm) with photoadduct retaining its structure in the nanocomposite. Presence of modified agglomerate regions in nanocomposite have been confirmed from FESEM which facilitates better charge separation in the material as observed from dielectric measurements. TG of nanocomposite shows better thermal stability as compared to both polyaniline and photoadduct owing to the strong interactions between the photoadduct nanoparticles and polyaniline matrix. The dielectric measurements (έ, ἒ, tanδ and σac) were studied as a function of frequency and their variation with frequency is explained by “Maxwell–Wagner” model. The nanocomposite shows higher value of dielectric constant (106) and higher value of ac-conductivity (109) as compared to pure PANI. The high value of dielectric constant and ac-conductivity of the nanocomposite makes the material suitable for energy storage applications and an effective electromagnetic interference shielding material both at low and high frequency.

Spectroscopic, computational and electrochemical studies on 2-(4-nitrophenyl)-1H-benzo[d]imidazole and its interaction with cationic surfactant cetyltrimethylammonium bromide

2-(4-Nitrophenyl)-1H-benzo[d]imidazole (4-NBI) was prepared and characterized by experimental and computational methods. Electrochemical reduction of the compound was studied in dimethyl sulphoxide media which showed that the nitro group of the molecule undergoes quasireversible three-step reduction producing –NH2 while the imidazole nitrogen bonded to hydrogen undergoes an irreversible one-electron reduction. The electronic spectra were studied by TDDFT computational method and compared with the experimental results which corroborated each other excellently. The interaction of 4-NBI with the cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated in aqueous solution at physiological pH (7.4) by UV–Vis spectroscopy. By using different nonlinear fitting methods binding parameters were evaluated for 4-NBI – CTAB micelles interaction. The results showed that the electrostatic interaction plays a major role over hydrophobic interaction in the binding of 4-NBI to CTAB micelles. The electrostatic interaction has also an important role in the distribution of 4-NBI between CTAB micelle–water phases. Gibbs free energy for the binding and distribution of 4-NBI between the bulk aqueous medium and surfactant micelles was calculated.

Spectrophotometric Determination of Norfloxacin in Pharmaceutical Formulations Based on Charge Transfer Reaction with Quinalizarin

A simple and rapid method has been developed for the determination of norfloxacin in bulk and pharmaceutical formulations. This method was based on the formation of bluish-green charge transfer complex of norfloxacin with quinalizarin in dimethyl sulphoxide medium. A 1:1 complex was formed between the drug and reagent almost instantaneously which has a λmax of 620 nm. Under optimum conditions of reagent concentration and reaction time, the calibration curve was found to be linear over the range of 8-100 µg mL-1of norfloxacin. The detection limit was found to be 0.27 µg mL-1 with Sandell's sensitivity 0.1287 µg cm−2. Stability constant (log K) was found to be 5.91±0.04 showing high stability of the complex. Molar absorptivity was found to be 2.479×103 L mol-1 cm-1. This method was subjected to analytical quality control. Recovery studies and interference studies were carried out. The proposed method was successfully applied to the determination of norfloxacin in pharmaceutical formulations.

A novel functionalisation process for glucose oxidase immobilisation in poly(methyl methacrylate) microchannels in a flow system for amperometric determinations

Different materials like glass, silicon and poly(methyl methacrylate) (PMMA) are being used to immobilise enzymes in microchannels. PMMA shows advantages such as its low price, biocompatibility and attractive mechanical and chemical properties. Despite this, the introduction of reactive functional groups on PMMA is still problematic, either because of the complex chemistry or extended reaction time involved. In this paper, a new methodology was developed to immobilise glucose oxidase (GOx) in PMMA microchannels, with the benefit of a rapid immobilisation process and a very simple route. The new procedure involves only two steps, based on the reaction of 5.0% (w/w) polyethyleneimine (PEI) with PMMA in a dimethyl sulphoxide medium, followed by the immobilisation of glucose oxidase using a solution containing 100U enzymes and 1.0% (v/v) glutaraldehyde. The reactors prepared in this way were evaluated by a flowing system with amperometric detection (+0.60V) based on the oxidation of the H2O2 produced by the reactor. The microreactor proposed here was able to work with high bioconversion and a frequency of 60samplesh−1, with detection and quantification limits of 0.50 and 1.66µmolL−1, respectively. Michaelis–Menten parameters (Vmax and KM) were calculated as 449±47.7nmolmin−1 and 7.79±0.98mmol. Statistical evaluations were done to validate the proposed methodology. The content of glucose in natural and commercial coconut water samples was evaluated using the developed method. Comparison with spectrophotometric measurements showed that both methodologies have a very good correlation (tcalculated, 0.05, 4=1.35<ttabled, 0.05, 4=2.78).

Ultrasonic and spectroscopic investigations of charge-transfer complexes in ternary liquid mixtures

Charge-transfer complexes formed between iodine ( σ-acceptor) and pyrrole, thiophene and pyridine ( π as well as n-electron donors) have been studied spectrophotometric and ultrasonic techniques at 303.15 K in dimethyl sulphoxide medium. The measured values of ultrasonic velocity, density and viscosity and the derived acoustical parameters such as adiabatic compressibility ( κ), free length ( L f), internal pressure ( π i), molar volume ( V m) and available volume ( V a) have been used to study the molecular interactions and the complexes of heterocyclic aromatic compounds. The excess thermodynamic parameters like excess velocity ( u E), excess adiabatic compressibility ( κ E), excess free length ( L f E), excess molar volume ( V m E) and excess available volume ( V a E) have been computed and the sign and magnitude of these parameters indicate the strength of interactions and the formation of charge-transfer complex. The formation constants of the charge-transfer complexes were determined by the Benesi–Hildebrand equations (optical method) and compared with those obtained from Kannappan method (ultrasonic method). The formation constants of complexes of iodine with aromatic compounds depend on the structure of the donor and acceptor molecules.

Inclusion complex of charge transfer probe 4-amino-3-methyl benzoic acid methyl ester (AMBME) with β-CD in aqueous and non-aqueous medium: medium dependent stoichiometry of the complex and orientation of probe molecule inside β-CD nanocavity

The absorption and emission characteristics of donor−acceptor charge transfer system 4-amino-3-methyl benzoic acid methyl ester (AMBME), capable of dual emission, i.e., local emission (LE) and charge transfer (CT) emission, have been investigated inside the β-cyclodextrin (β-CD) nanocavity in the aqueous and non-aqueous dimethylsulphoxide (DMSO) medium. Large enhancement of both LE and CT band in aqueous β-CD medium is due to decrease in non-radiative processes in less polar and restricted environment. Whereas in non-aqueous DMSO medium the CT process is hindered as a result CT intensity decreases with enhancement of LE band. These spectral differences indicate that in aqueous medium the donor –NH2 group sticking in the hydrophilic region of β-CD cavity whereas in non-aqueous DMSO medium it exists in the hydrophobic part of the cavity. Spectral characteristics indicate that different stoichiometry of host–guest inclusion complexes are formed in aqueous and non-aqueous β-CD medium.

New spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations.

Two simple, sensitive and economical spectrophotometric methods were developed for the determination of nifedipine in pharmaceutical formulations. Method A is based on the reaction of the nitro group of the drug with potassium hydroxide in dimethyl sulphoxide (DMSO) medium to form a coloured product, which absorbs maximally at 430 nm. Method B uses oxidation of the drug with ammonium molybdate and subsequently reduced molybdenum blue is measured at 830 nm. Beer's law is obeyed in the concentration range of 5.0-50.0 and 2.5-45.0 microg ml(-1) with methods A and B, respectively. Both methods have been successfully applied for the assay of the drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. The reliability and the performance of the proposed methods are established by point and interval hypothesis tests and through recovery studies.

Antiproliferative effect of 1,4-phenylenebis(methylene)selenocyanate (p-XSC) on colonic epithelium of patients with adenomatous polyps in vitro.

We have consistently shown that the organoselenium compound 1,4-phenylenebis(methylene)selenocyanate (p-XSC) is a superior cancer chemopreventive agent and less toxic than selenite or certain naturally-occurring selenoamino acids. To elucidate the effects of p-XSC on human colonic mucosa, biopsies from endoscopically normal sigmoid colon of 30 patients with adenomatous polyps were incubated with p-XSC at concentrations of 1, 2 and 5 micromol/l dissolved in dimethylsulphoxide (DMSO). Biopsies incubated with DMSO or pure culture medium served as a control. Proliferating cells were labelled by bromodeoxyuridine immunohistochemistry and the labelling index (LI) was computed. Upper crypt labelling index (LI of crypt compartments 4+5) and Phih value, which are both discriminators of the expansion of the proliferative zone, were significantly lower after incubation with 1 and 5 micromol/l p-XSC, respectively (LI 4+5: 0.8 and 1.0; Phih value: 2.1 and 2.4), as compared with DMSO (LI 4+5: 3.6 and 4.5; Phih value: 7.0 and 8.3) or culture medium (LI 4+5: 3.3 and 4.5; Phih value: 7.2 and 8.1) (P<0.005 and P<0.05 by Friedman's block test). A trend towards lower levels of LI 4+5 (P=0.059) and Phih value (P=0.075) were seen after 2 micromol/l p-XSC incubation compared with DMSO. Since hyperproliferation of colonic crypt cells with expansion of the proliferative zone is regarded as a biomarker of increased cancer risk, the antiproliferative effects of p-XSC especially on upper crypt LI and Phih value may indicate a possible protective effect of this organoselenium compound in the prevention of human colon cancer development.

Studies on Synthesis and Characterization of Charge Transfer Polymerization of Styrene and Alkyl Methacrylates

Copolymers involving styrene and homologues of alkyl methacrylates (viz., methyl, ethyl, and butyl methacrylates) were synthesized at 60°C by employing a mixture of n‐butylamine and carbontetrachloride as charge transfer (CT) initiators in dimethyl sulphoxide medium. The CT complex was characterized by UV spectroscopy while the respective copolymers were characterized by employing infrared (IR) and 1H NMR spectroscopy. The copolymer compositions were determined by using 1H NMR spectroscopy and the reactivity ratios were computed by Fineman–Ross (F–R) and Kelen–Tudos (K–T) methods. The reactivity ratios of Sty‐MMA and Sty‐EMA copolymers indicate that higher level of styrene is incorporated in the copolymer. On the other hand the Sty‐BMA system exhibits different behavior. The higher value of r 2 is obtained denoting that BMA is more active than styrene and hence, more BMA is present in the copolymer chain. In Sty‐MMA and Sty‐BMA systems, the product of r 1 and r 2 is greater than 1, representing the formation of high degree of random copolymers. However, in the case of Sty‐EMA, the product of r 1 and r 2 is less than 1 indicating the formation of alternating copolymer.

Mediated electron transfer of polyethylene oxide-modified superoxide dismutase by methyl viologen

Methyl viologen was found to efficiently mediate the electron transfer between polyethylene oxide-modified superoxide dismutase and the electrode in dimethyl sulphoxide media. Based on the potential-step chronoamperometric experiments, the rate constant for the mediated electron transfer was estimated to be ≈ (1−2) × 10 3M −1s −1.

Proteoglycan synthesis in human erythroleukaemia (HEL) cells.

Synthesis of sulphated proteoglycans was compared in human erythroleukaemia (HEL) cells grown under control conditions and under stimulation by dimethyl sulphoxide (DMSO) and phorbol 12-myristate 13-acetate (PMA). Synthesis of [35S]sulphate-labelled proteoglycans by DMSO-treated cells was decreased by about 35% relative to controls, but synthesis of proteoglycans by PMA-treated cells increased 3-4-fold. Control and DMSO-treated cells secreted 65% of the newly synthesized proteoglycans, but PMA-treated cells secreted more than 90%. Sepharose CL-6B chromatography and SDS/PAGE suggested the presence of several proteoglycans in the cells and culture medium. The PMA-treated cells synthesized a low-Mr proteoglycan (Kav. 0.3( that was not present in controls and DMSO-treated cultures. The proteoglycans of the cells and medium from control, DMSO-treated and PMA-treated cultures could be separated into three fractions by octyl-Sepharose chromatography. The proteoglycans were resistant to trypsin but were degraded by Pronase and papain to fragments similar in size to the NaOH/NaBH4-generated glycosaminoglycans. The average chain length of the glycosaminoglycans (Kav. 0.20 on Sepharose CL-6B for controls) was decreased by DMSO (Kav. 0.25) and by PMA (Kav. 0.30-0.38). Chondroitin ABC lyase digestion of the proteoglycans from the medium of the control cultures produced two core proteins at Mr 31,000 and 36,000. The DMSO medium proteoglycans had only the 31,000-Mr core protein, and the PMA culture medium proteoglycans had core proteins of Mr 27,000, 31,000 and 36,000. Changes in synthesis of proteoglycans induced by DMSO or PMA may have relevance for the maturation of haematopoietic cells.

Reactions of tetrachlorodioxouranate(VI) ion with neutral and protic ligands

The reactions of [bipyH2][UO2Cl4]·3H2O (bipyH2=diprotonated 2,2′-bipyridyl) with a series of neutral and protic oxygen donor ligands have been investigated. N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA) and dimethyl sulphoxide (DMSO) gave compounds of the type [bipyH2][UO2Cl4(L)2] (L=DMF or DMA) and [bipyH2][UO2Cl4(DMSO)n] (DMSO)3-n (n=1 or 2), while [bipyH2][UO2Cl4-(3PNO)(DMSO)n](DMSO)2-n (n=1 or 2) and [bipyH][UO2Cl3(4PNO)(DMSO)] were obtained with 3-picoline N-oxide (3PNO) and 4-picoline N-oxide (4PNO) respectively from DMSO medium. With excess 2-picoline N-oxide (2PNO) the compound [bipyH][UO2Cl3(2PNO)](DMSO) was obtained. Reaction with acetyl acetone (AcAcH) and 8-hydroxy quinoline (QH) in 1:1 mole ratio in DMSO gave compounds of the type [bipyH2][UO2Cl3(L′)(DMSO)] (L′=AcAc or Q). The compounds have been investigated by i.r. spectra, powder x-ray diffraction and molar conductivity measurements.

Rapid spectrophotometric method for the determination of fluorene

Fluorene reacts rapidly with the sodium salt of 1,2-naphthoquinone-4-sulphonic acid in an alkaline dimethyl sulphoxide medium containing sodium methoxide and methanol to give a coloured product. The time necessary for this reaction was 30 s with continuous and thorough stirring. The intensity of the colour was measured spectrophotometrically at 655 nm following dilution with methanol. The apparent molar absorptivity is approximately 8.7 × 103 l mol–1 cm–1, and Beer's law is obeyed over the concentration range 1–16 µg ml–1 of fluorene. The colour was stable if the product was kept in a tightly stoppered flask for at least 1.5 h in the presence of small amounts of 2,6-di-tert-butyl-4-methylphenol.