Long-Di Li

Syntheses of steroid-based molecularly imprinted polymers and their molecular recognition study with spectrometric detection

Recognition of five steroid compounds, beta-estradiol, ethynylestradiol, estradiolbenzoate, testosterone and methyltestosterone were studied using a synthesized molecularly imprinted polymer (MIP). When beta-estradiol was used as the template molecule, the polymer was synthesized with methacrylic acid (MAA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the cross linking agent through non-covalent interactions. It is found that the kind of porogen solvent and the polymerization conditions greatly affected the binding ability of a MIP to a certain molecule. Releasing of the template was performed by continuous extraction with methanol containing 10% acetic acid in a Soxhlet extractor. Our results indicated that such carefully synthesized MIP showed specific affinity toward beta-estradiol in the adsorption process.

Non-protected fluid room temperature phosphorescence of several naphthalene derivatives

In our previous work, we reported that with TlNO(3) as a heavy atom perturber and Na(2)SO(3) as a deoxygenator, room temperature phosphorescence (RTP) emission of dansyl chloride and its amino acid derivatives can be induced directly from their aqueous solution without a protective medium. Is this kind of fluid luminescence phenomenon unique for the dansyl chloride compounds? The present work has shown that many naphthalene derivatives can also exhibit RTP emission in their aqueous solutions under similar conditions in the absence of a protective medium. Such an RTP emission phenomenon could be denoted as nonprotected fluid room temperature phosphorescence (NP-RTP). In order to further understand this new luminescence phenomenon, the substituent group effects and the favorable chemical structure of compounds for NP-RTP emissions are discussed in detail.

Aqueous two-phase extraction system of sodium perfluorooctanoate and dodecyltriethylammonium bromide mixture and its application to porphyrins and dyes

A new aqueous two-phase system is developed consisting of sodium perfluorooctanoate (SPFO) and dodecyltriethylammonium bromide (C12NE) cationic–anionic surfactant mixture. The two phases with a clear interfacial boundary formed when SPFO to C12NE molar ratio is 1.2:1 in the presence of 5% (v/v) nitric acid. The top phase is transparent and the bottom phase is opalescent. Extractions of dyes, porphyrin compounds with the two-phase system were performed. The results show that hydrophobic molecules were extracted into the surfactant-rich bottom phase with high extraction efficiencies. Positively charged porphyrins were extracted into the bottom phase with higher extraction efficiencies than negatively charged porphyrins. Such a new anionic surfactant two-phase system would be complementary to the C12NE–SDS (sodium dodecyl sulfate) cationic two-phase which has been proven to be effective for extractions of porphyrins with substituted groups like carboxyl or sulfonic acid groups.

Aqueous two-phase system of cationic and anionic surfactant mixture and its application to the extraction of porphyrins and metalloporphyrins

Abstract Aqueous two-phase system is obtained when a cationic surfactant with bigger alkyl polar head groups such as dodecyltriethylammonium bromide (C12NE) is mixed with an anionic surfactant like sodium dodecyl sulfate (SDS) at certain surfactant concentrations and molar ratios. When C12NE is in excess, the top phase is opalescent and is a surfactant-rich micellar solution, while the bottom phase is transparent and is a dilute micellar solution. Such a new aqueous two-phase separation system is employed in extractive separation practice. Several dyes with different chemical structure like anthraquinone, methyl red and methylene blue partitioned in the two-phase system are investigated. Porphyrin compounds and metalloporphyrins, i.e., hematoporphyrin (hemato), uroporphyrin (uro), Cu-TPPS4 (tetraphenylporphine tetrasulfonic acid), Zn-TPPS4, Cu-T-4(TAP)P (tetrakis(p-trimethylammoniophenyl) porphine), are also extracted with the present two-phase system. It is found that hydrophobic as well as charge interaction between a substance partitioned in the system and the micelles are predominant factors that govern the extraction.

Room-temperature phosphorescence of dansyl chloride solution in the absence of protective medium and its medium effect

Abstract A unique fluid room-temperature phosphorescence (RTP) method, which is different from the RTP methods developed previously and needs no microscopically ordered medium, is developed. The RTP emission of dansyl chloride (DNS-Cl) and its amino acid derivatives can be induced directly in aqueous system by the addition of thallium nitrate as heavy atom perturber and sodium sulfite as deoxygenator, λ ex λ em = 326 574 nm . A good linearity between the RTP intensity and the concentration of DNS-Cl in the range 2.0 × 10 −7 −1.0 × 10 −5 mol/l was obtained with a detection limit of 1.9 × 10 −8 mol/l. A comparative study of RTP of DNS-Cl in the presence of cyclodextrins (CDs), surfactant micelle, organic solvent and bovine serum albumin (BSA) has also been carried out. This fluid RTP emission system of DNS-Cl is very transparent and stable, and can be modulated by different organic solvents. The quenching behavior of RTP by BSA presents a satisfactory linearity between the concentration of BSA and I RTP , which can be used in the quantitative analysis of BSA.

Selective extraction of alkali metal cations with proton-ionizable dibenzo-16-crown-5 fluoroionophores

Abstract Two fluorescent ionophores of N-dansyl sym-(R)-dibenzo-16-crown-5-oxyacetamide HDAC (R=H) and PDAC (R=propyl) are developed for alkali metal cation sensing. Extraction of certain alkali metal cations into 1,2-dichloroethane by each ionophore result in a hypsochromic band shift and a fluorescence intensity increase in its emission spectrum. This fluorescent response is based upon the proton-ionizable function of the dansylamide fluorophore. Extraction constants (Kex) and selectivity coefficients (S) for Li+, Na+, and K+ are obtained. HDAC exhibits strong binding ability for both Na+ and K+, whereas PDAC shows a much stronger binding ability for Na+ than K+. It is proposed that PDAC has a preorganized conformation in which the geminal propyl group orients the carboxyl group of the fluoroionophore-containing side arm over the crown ether cavity favoring Na+ complexation.

Medium effects on fluorescence of ciprofloxacin hydrochloride

The medium (pH, organic solvents, cyclodextrin (CD) or surfactants) effects on the fluorescence of ciprofloxacin hydrochloride (CPFX.HCl) were studied in detail. It is found that the three acid constants of ciprofloxacin (CPFX) are near to each other. Therefore the relation curve between pH and fluorescence intensity has no strident change and keeps relative stable in the pH range of 2-7. When pH was in the range of 5.5-6.0, the fluorescence intensity of CPFX reached the max. The kind and amount of organic solvent added to the luminescent system have various effects. Ethanol quenched fluorescence and the fluorescence excitation wavelength is red shift at first and then blue shift. Acetone has complicated effects on the fluorescence properties of CPFX.HCl solution. The experiment result shows that acetone is really a quencher when its volume content in the system is from 0 to 20%, but when its content is 90%, the signal intensity is unexpectedly one and a half times as much as that of no acetone. This means that there is a strong interaction between the acetone and CPFX; CPFX.H(+) could be included into the gamma-CD but the capping effect is not notable. The effect of cationic surfactant cetyltrimethylammonium bromide and non-ionic surfactant TX-100 and TX-80 on CPFX fluorescence was unimpressive, but the anionic surfactants effect is aberrant. The fluorescence intensity of CPFX.HCl solution experiences three stages of increasing, decreasing and increasing in turn, as sodium dodecyl sulfate is adding gradually. But for sodium lauryl sulfonate, there are only two stages of decreasing and increasing with the concentration increasing. It is problematic to illustrate clearly the effect mechanism of acetone and anionic surfactant at present. Undoubtedly, the experimental results in this paper should be useful in practice works and the research is worth studying still further.

Determination of trace mercury by solid substrate room temperature phosphorescence quenching method based on lead carboxymethyl cellulose (Pb(CMC)2) particles containing luminescent salicyl fluorones molecules

Luminescent particles of lead carboxymethyl cellulose (Pb(CMC)(2)), which contains salicyl fluorones (THBF), Pb(CMC)(2)-THBF, were synthesized by sol-gel method. Pb(CMC)(2)-THBF can emit intense and stable solid substrate room temperature phosphorescence (SS-RTP) on filter paper. EDTA can chelate the Pb(2+) in Pb(CMC)(2)-THBF, causing it decompose into aqueous soluble components PbY(2-), CMC(-) and THBF, and these components can react with Hg(2+) to form (CMC)(2)Hg-THBF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS-RTP quenching method was established. The linear range of this method is 2.0-40.0fgspot(-1) (5.0-100.0pgml(-1)) of Hg(2+), with a detection limit (LD) of 0.26fgspot(-1), and the regression equation of working curve is [Formula: see text] (fgspot(-1), 0.4mul spot(-1)), r = 0.9994. This method has been applied to the determination of trace mercury in water sample with satisfactory results. The mechanism of SS-RTP emission is also discussed.

Studies on properties and application of non-protected room temperature phosphorescence of propranolol.

A direct and simple non-protected room temperature phosphorimetry (NP-RTP) for determine propranolol, which using I- as a heavy atom perturber and sodium sulfite as a deoxygenator, has been developed. The phosphorescence peak wavelength maxima lambda(ex)/lambda(em) = 288/494, 522 nm. The analytical curve of propranolol gives a linear dynamic range of 8.0 x 10(-8)-2.0 x 10(-5) mol l(-1) and a detection limit of 3 x 10(-8) mol l(-1). The influence of I- concentration on RTP lifetime of propranolol was studied and the luminescence kinetic parameters were calculated. It is found that the relation between I- concentration (x) and RTP lifetime (tau) can be expressed as tau = 1.25e(-0.477x) and the rate constants of phosphorescence emission k(p) was 0.800 per ms. The method was applied directly to determination of propranolol in urine and drug tablets with a satisfactory result. The recoveries were 96.6-97.4% and the relative standard deviation was 2% for the 1.00 x 10(-6)-4.00 x 10(-6) mol l(-1) propranolol in spiked urine sample.

Study of properties on non-protected room temperature phosphorescence and delayed excimer fluorescence of pyrene solution

A strong and stable room temperature phosphorescence (RTP) and delayed excimer fluorescence signal located at 596 and 475 nm, respectively, can be induced for pyrene solution in the absence of any protective medium only use KI or TlNO3 as a heavy atom perturber (HAP) and Na2SO3 as a deoxygenator. Both lifetimes of RTP and the delayed fluorescence are in the order of X-ms and the intensities are changed with kind and amount of HAP, but the peak positions are same and there is a iso-luminescent point in the emission spectra corresponding to emission at 475 nm and at 596 nm. The optimum conditions and the effects of kind and amount of HAP and organic solvents on luminescence properties of pyrene solution were studies in detail, and the photophysical process in the presence of KI or TlNO3 for phosphorescence and delayed excimer fluorescence emission of pyrene solution was discussed.