Efficient synthesis of terminal 4-methylumbelliferyl labeled 5-fluoro-2′-deoxyuridine-5′-O-tetraphosphate (Um-PPPP-FdU): a potential probe for homogenous fluorescent assay

Efficient synthesis of 5-fluoro-2′-deoxyuridine-5′-O-tetraphosphate bearing 4-methylumbelliferyl label on the terminal phosphate is reported. This compound has the potential as a promising probe molecule for homogenous fluorescent polymerase assay. This class of compounds will aid in quantification of cellular internalization and DNA incorporation of nucleotide based chemotherapeutic agents to offer mechanistic insights.     

Influence of calcium lactate and pH on emulsification of low-methoxylated citrus pectin in a Pickering emulsion

An emulsion was prepared by homogenizing 30% rapeseed oil with 70% (w/w) aqueous solution. The emulsion viscosity increased when the concentrations of calcium lactate and low-methoxylated citrus pectin (LMP) in the emulsion were increased. A stable emulsion was obtained when the concentrations of LMP and calcium lactate were 1% and 9?mM at pH 3, respectively. Optical microscopy and laser scanning confocal microscopy revealed that the stable emulsion was a Pickering emulsion. In the Pickering emulsion, LMP with calcium formed micro gels that can be absorbed on the oil surface. The emulsifying property of LMP could widen the applications of pectin.     

An efficient method to synthesize HMX by nitrolysis of DPT with N_2O_5 and a novel ionic liquid

A novel polyethylene glycol(PEG)-200-based dicationic acidic ionic liquid(PEG200-DAIL)was used to synthesize HMX from DPT by nitrolysis with N2O5.It was found that either N2O5 or PEG200-DAIL could improve the yield.Furthermore,the combined use of PEG200-DAIL and N2O5 could increase the yield of HMX to 64%with the used quantity of HNO3 decreased.dramatically     

Design and synthesis of a novel fluorescent protein probe for easy and rapid electrophoretic gel staining by using a commonly available UV‐based fluorescent imaging system

A new fluorescent molecular probe, methyl 3‐(3,5‐bis((bis(pyridin‐2‐ylmethyl)amino)‐methyl)‐4‐hydroxyphenyl)‐2‐(5‐(dimethylamino)naphthalene‐1‐sulfonamido) propanoate, dizinc(II) chloride salt (Dansyl‐ 1 ‐Zn(II)), which possesses Zn(II) complexes and a dansyl group, was designed and synthesized to enable the detection of proteins in solution and in high‐throughput electrophoresis by using a UV‐based detection system. Dansyl‐ 1 ‐Zn(II) exhibited weak fluorescence in the absence of proteins and strong green fluorescence at approximately 510 nm in the presence of BSA upon irradiation with light at a wavelength of 345 nm. Compared with conventional protocols for in‐gel SDS‐PAGE protein staining (e.g. silver staining, SYPRO Ruby, and Oriole), the operating times of which range from 90 min to overnight, Dansyl‐ 1 ‐Zn(II) allowed 1‐step protein staining (SDS‐PAGE →Staining →Detection) and shortened the operating time (35 min) with high sensitivity (LOD: 1 ng or less) under 312‐nm or 365‐nm light excitation with orange or red emission filters, respectively. Moreover, Dansyl‐ 1 ‐Zn(II) was successfully applied to protein identification by MS via in‐gel tryptic digestion, Western blotting, and Native‐PAGE. Accordingly, Dansyl‐ 1 ‐Zn(II) may facilitate highly sensitive and high‐throughput protein detection, and it may be widely applicable as a convenient tool in various scientific and medical fields.     

Studies of bio-mimetic medium of ionic and non-ionic micelles by a simple charge transfer fluorescence probe N,N-dimethylaminonapthyl-(acrylo)-nitrile

In this report we have studied micellization process of anionic, cationic and non-ionic surfactants using N,N-dimethylaminonapthyl-(acrylo)-nitrile (DMANAN) as an external fluorescence probe. Micropolarity, microviscosity, critical micellar concentration of these micelles based on steady state absorption and fluorescence and time resolved emission spectroscopy of the probe DMANAN show that the molecule resides in the micelle-water interface for ionic micelles and in the core for the non-ionic micelle. The effect of variation of pH of the micellar solution as well as fluorescence quenching measurements of DMANAN provide further support for the location of the probe in the micelles.     

Synthesis,structure and fluorescent properties of CdII,ZnII and NiII complexes with 2-amino-6-methylbenzothiazole and 5-nitroisophthalate as ligands

Three new coordination polymers, [M(Ambt)₂(Nip)] _n (M = Cd for 1 and Zn for 2) and [Ni_0.5(Nip)(H₂O)₂] (HAmbt) (3) (H₂Nip = 5-nitroisophthalic acid, Ambt = 2-amino-6-methylbenzothiazole), have been synthesized by hydrothermal methods and are further characterized by X-ray diffraction, IR spectra, elemental analysis, TG-DTA and fluorescence spectra. The structural analyses suggest that 1 and 2 are 1-D chains bridged by Nip anions, in which Ambt is a monodentate ligand and the carboxylate groups of Nip are monodentate and chelating bidentate. Complex 3 consists of two individual fragments, six-coordinate mononuclear Ni^II and HAmbt cation, in which HAmbts are encapsulated into the concave of the 2-D layer formed by mononuclear units through classic N?H·· · O hydrogen bonds. Abundant hydrogen bond interactions drive the formation of packing structure of the complexes. The three solid complexes display strong emission peaks from intraligand charge transfer similar to free Ambt at room temperature.     

The adsorption of hydrophobically modified carboxymethylcellulose on a hydrophobic solid: effects of pH and ionic strength

Carboxymethylcellulose with 1.2% dodecyl groups (per glucose unit) was prepared by amidation with dodecylamine. This polymer behaves as a hydrophobically modified polyelectrolyte with the following thickening properties which are determined from viscosity data. It adsorbs from aqueous solution on spin-coated polystyrene films to various extents, depending on pH and ionic strength. The adsorbed amount has a surprising minimum at around pH 6 which coincides with a maximum in viscosity of a dilute solution, and with a very pronounced maximum in the hydrodynamic radius as determined from dynamic light scattering. To our knowledge, such behavior has not been reported before. It suggests that at low pH the polymer is present in the form of small aggregates which upon increasing the pH first swell and then break up into single molecules. Received: 19 June 1997 Accepted: 5 January 1998     

Photocatalytic Oxidation of NO2 on TiO2: Evidence of a New Source of N2O5

N₂O₅ is an important intermediate in the atmospheric nitrogen cycle. Using a flow tube reactor, N₂O₅ was found to be released from the TiO₂ surface during the photocatalytic oxidation of NO₂, revealing a previously unreported source of N₂O₅. The rate of N₂O₅ release from TiO₂ was dependent on the initial NO₂ concentration, relative humidity, O₂/N₂ ratio, and irradiation intensity. Experimental evidence and quantum chemical calculations showed that NO₂ can react with the surface hydroxyl groups and the generated electron holes on the TiO₂, followed by combining with another NO₂ molecule to form N₂O₅. The latter was physisorbed on TiO₂ and had a low adsorption energy of −0.13 eV. Box model simulations indicated that the new source of N₂O₅ released from TiO₂ can increase the daytime N₂O₅ concentration by up to 20 % in urban areas if abundant TiO₂-containing materials and high NOx concentrations were present. This joint experimental/theoretical study not only demonstrates a new chemical mechanism for N₂O₅ formation but also has important implications for air quality in urban areas.     

荧光试剂3-苯基-5-苯甲酰基-2-硫代-4-噻唑啉酮的合成及应用

本文报道了荣光试剂3-苯基-5-苯甲酰基-2-疏代-4-噻唑啉酮（PBTT）的合成。产品经拉层桥提纯，用元素分析、IR、1HNMR和MS确证了其结构；研究了它的荧光性质。在PH5．6时，与痕量镜（Ⅲ）形成络合物。且在λex/λem=305nm／405nm产生强荧光。测定了人工合成样品中的铥，结果比较满意。     

The synthesis and structure of La5Pb3Z,Z  N,O. Interstitial derivatives of a Cr5B3-Type structure

Suitable proportions of La, La₄Pb₃ and La₂O₃ or LaN reacted in pressed pellets at 1050°–1250°C result in high yields of the title compounds. Single crystal X-ray studies of the oxide show it to be an isopointal, interstitial derivative of the Cr₅B₃ structure (I4/mcm, Z = 4, a = 8.6895(2) Å, c = 14.540(1) Å, R/R_w = 3.0/3.5%). Oxygen or nitrogen atoms are bound in (La2)₄ tetrahedra within chains along (0, 1 /2, z). Negligible dimerization of the type characteristic of Cr₅B₃ is indicated by the Pb2? Pb2 separation, 3.550(1) Å. The structure is compared with other related examples.     

Adsorption and desorption of colloidal particles on glass in a parallel plate flow chamber—Influence of ionic strength and shear rate

The adsorption and desorption rates of 736 nm diameter polystyrene particles on glass were studiedin situ using a parallel plate flow chamber and automated image analysis. Adsorption and desorption rates were measured simultaneously during deposition, enabling the determination of initial deposition rates, blocked areas per particle, desorption rate coefficients, and the number of adhering particles in the stationary state. Deposition experiments were done from suspensions with different potassium nitrate concentrations (1, 10 and 50 mM) and at varying shear rates (15 to 200 s^–1). The initial deposition rate, the desorption rate, the blocked area per particle and the number of adhering particles in the stationary state showed major variations with the shear rate and the ionic strength of the suspension. At low ionic strength, the number of adhering particles showed an oscillatory behavior in time, presumably due to a varying interaction between particle and collector surface. Blocked areas, determined from deposition kinetics, ranged 705 to 2374 cross-sections at low ionic strength, and from 10 to 564 at high ionic strength and corresponded well with those estimated from local pair distribution functions which were obtained from an analysis of the spatial arrangement of the adhering particles.     

Influence of ionic strength and shear rate on the desorption of polystyrene particles from a glass collector as studied in a parallel-plate flow chamber

The residence-time-dependent desorption during the deposition of polystyrene particles 736 nm in diameter on glass was studied in situ using a parallel-plate flow chamber and automated image analysis. Comparison of successively grabbed images yielded the initial desorption rate coefficient, and final desorption rate coefficient and a relaxation time for the transition from the initial to the final desorption state, i.e. ageing of the bonds. Desorption experiments were performed from suspensions with different potassium nitrate concentrations (1, 10 and 50 mM) and at varying shear rates (15–200 s⁻¹. The initial desorption rate coefficient β₀ ranging from 1 × 10⁻³ to 20 × 10⁻³s⁻¹, and the final desorption rate coefficient β_∞, ranging from 0.01 × 10⁻³ to 0.65 × 10⁻³s⁻¹ were both larger than the desorption rate coefficients calculated neglecting a possible residence time dependence. These desorption rate coefficients, β, ranged from 0.005 × 10⁻³ to 0.40 × 10⁻³s⁻¹. The relaxation times, at which the adhesion of the polystyrene particles entered a more irreversible state of adhesion compared with their initial state of adhesion, varied from 100 to 1000 s. The desorption rate coefficients as well as the relaxation time showed major variations with the shear rate and the ionic strength of the suspension. At high ionic strength, the initial and final desorption rate coefficients increase and the relaxation time decreases with increasing shear rate, whereas at low ionic strength the desorption rates decrease and the relaxation time increases with increasing ionic strength. This study provides direct evidence that the interaction forces between adhering particles and a collector surface change over time.     

铽与4—酰代吡唑啉酮—5的三元配合物的合成与荧光性质

合成并表征了一系列铽与含不同４－酰代的１－苯基－３－甲基－吡唑啉酮－５的三元配合物Ｔｂ９Ｌ）３．２Ｈ２Ｏ和Ｔｂ（Ｌ）３．Ｄｉｐｙ「Ｌ＝１－苯基－３－甲基－４－乙酰基吡啥林酮－５（ＰＭＡＰ），１－苯基－３－甲基－４－丙酰基吡唑啉酮－５（ＰＭＰＰ），１－苯基－３－甲基－４－异丁酰基吡唑啉酮－５（ＰＭＩＢＰ），１－苯基－３－甲基－４－特戊酰基吡唑啉酮－５（ＰＭＰＶＰ），１－苯基－３－甲基－４－苯甲酰基吡     

Synthesis and investigation on the interaction with calf thymus deoxyribonucleic acid of a novel fluorescent probe 7-oxobenzo[b][1,10]phenanthroline-12(7H)-sulfonic acid

In this paper, the synthetic route of a potential antitumor reagent, benzo[b][1,10] phenanthrolin-7(12H)-one (BPO), was improved. A sulfonic group was introduced to BPO to form a new compound, 7-oxobenzo[b][1,10]phenan-throline-12(7H)-sulfonic acid (OPSA), in order to enhance its water-solubility. The molecular structure of OPSA has been confirmed by IR, UV, MS, ¹H NMR and elements analysis. It was proved in our experiments that DNA could quench the fluorescence of OPSA and the maximum quenched intensity appeared at 408 nm (λ_ex = 284 nm). The quenched fluorescence intensity was proportional to the concentration of DNA. Based on this phenomenon, OPSA had been used as the fluorescent probe for detection of calf thymus DNA (ct-DNA) and the corresponding linear response range was from 1.0 to 150.0 μg mL⁻¹ and the limit of detection (LOD) was 3.8 ng mL⁻¹. Its interaction with ct-DNA was investigated by fluorescence, absorption and viscosity measurements. When binding to ct-DNA, OPSA showed obvious fluorescence quenching and the quenched intensity was stable with the presence and absence of NaCl. The absorption spectra of OPSA had no evidence of increasing or decreasing when ct-DNA was added. The viscosity of OPSA and ct-DNA mixture showed no obvious change comparing with the viscosity of ct-DNA along. The results suggested that the interaction between OPSA and ct-DNA was groove binding in nature. Scatchard plots constructed from fluorescence titration data gave a binding constant of 8.9 × 10⁵ L mol⁻¹ and a binding site size of 0.35 base pairs per bound drug molecule.     

Influence of Initial pH Value on the Adsorption of Reactive Black 5 Dye on Powdered Activated Carbon: Kinetics,Mechanisms, and Thermodynamics

The aim of this work was to investigate the influence of initial pH value (pH₀) on the isothermal adsorption of Reactive Black 5 (RB5) dye on commercial powdered activated carbon. Four initial pH values were chosen for this experiment: pH₀ = 2.00, 4.00, 8.00, and 10.00. In order to investigate the mechanism of adsorption kinetic, studies have been performed using pseudo-first-order and pseudo-second-order kinetic models as well as an intraparticle diffusion model. In addition, thermodynamic parameters of adsorption were determined for pH₀ = 4.00. Results of this research showed that the initial pH value significantly influences the adsorption of RB5 dye onto activated carbon. The highest adsorption capacities (q_e) and efficiencies of decolouration were observed for initial pH values of pH₀ = 2.00 (q_e = 246.0 mg g⁻¹) and 10.00 (q_e = 239.1 mg g⁻¹) due to strong electrostatic interactions and attractive π···π interactions, respectively. It was also shown that the adsorption of RB5 dye on activated carbon at all initial pH values is kinetically controlled, assuming a pseudo-second-order model, and that intraparticle diffusion is not the only process that influences on the adsorption rate.     

Dual-sensitive probe 1-imidazole-2-(5-benzoacridine)-ethanone for the determination of amines in environmental water using HPLC with fluorescence detection and online atmospheric chemical ionization-mass spectrometry identification

Dual-sensitive probe of 1-imidazole-2-(5-benzoacridine)-ethanone (IBAE) for the determination of free amines with fluorescence detection and online highly sensitive atmospheric chemical ionization-mass spectrometry identification (APCI-MS) has been developed. 2-(Benzoacridine)-5-acetic acid (BAAA) reacts with coupling agent N,N′-carbonyldiimidazole (CDI) to form a highly activated amide intermediate 1-imidazole-2-(5-benzoacridine)-ethanone (IBAE), which is dual-sensitive probe. The amide intermediate (IBAE) reacts preferably with amines in dimethylformamide (DMF) solvent to give the high yields of derivatives. IBAE-amine derivatives are not only sensitive to fluorescence but also to MS ionizable efficiency. The percent ionization δ values change from 0 to 57.32% in aqueous acetonitrile and from 0 to 62.14% in aqueous methanol. The relative standard deviations of the peak areas with fluorescence detection for each amine are <1.24% (40 ng/ml, n = 6). The fluorescence detection limits (at a signal-to-noise ratio of 3) are in the range of 0.15-0.50 ng/ml. The online APCI-MS detection limits are in the range of 2.07-8.51 ng/ml (at a signal-to-noise ratio of 3). Therefore, the facile IBAE intermediate derivatization allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amines in environmental water.     

p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex

The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, = 108.98(1)°, = 105.02(2)°, = 95.21(1)°, Z = 2, D _c = 1.059 kg m^-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.     

Fluorescent detection of amidinium-carboxylate and amidinium formation using a 1,8-diphenylnaphthalene-based diamidine: dicarboxylic acid recognition with high fluorescence efficiency

A 1,8-diphenylnaphthalene-based diamidine (1) ‘turn-on’ fluorescent probe for the detection of dicarboxylic acids has been designed and synthesized. The fluorescence spectra of the diamidine 1 with carboxylic acids that showed two different fluorescence bands, which corresponded to the amidinium-carboxylate (λ_em=410–430 nm) and amidinium (λ_em=440–470 nm as a broad band, which consisted from two peaks) formation, were confirmed by DOSY NMR and TD-DFT calculations. The complexation of diamidine 1 with dicarboxylic acids, which have sufficient distances between the two carboxylic groups for binding to the diamidine 1 (dicarboxylic acids 3, 4, and α,ω-dicarboxylic acids 6 (C₆–C₂₀)), showed the formation of 1:1 complexes (i.e., amidinium-carboxylate formation). On the other hand, for the complexation with monocarboxylic acids and dicarboxylic acids having insufficient distances between the two carboxylic groups (benzoic acid 5, acetic acid 7, and α,ω-dicarboxylic acids 6 (C₃–C₅)), formation of the amidinium (1·2H⁺) was observed. Relatively similar binding constants (10⁻⁵) for the complexation of the diamidine 1 with dicarboxylic acids 6, which depend on their chain length (strain), were observed due to the flexibility of the 1,8-diphenylnaphthalene unit. Additionally, for the complexation of the diamidine 1 with dicarboxylic acids, higher fluorescence quantum yields (Φ_fl: up to 80%) were observed when compared to the binding of the diamidine 2 (Φ_fl: up to 35%).