Fluorescein-based fluorescent and colorimetric chemosensors for copper in aqueous media

Two new fluorescein-based chemosensors for Cu²⁺ were designed with highly selective “off-on” behavior, one of them working in both absorption and emission, the other only in absorption. Binding to Cu²⁺ binding is reversible, as indicated by the bleaching of the color when the metal is extracted. The compounds form the basis for rapid, selective and sensitive Cu²⁺ chemosensors in aqueous media.     

Bottlebrush‐shaped copolymers with cellulose diacetate backbone by a combination of ring opening polymerization and ATRP

Graft copolymers with cellulose diacetate (CDA) backbone and both the poly(ε‐caprolactone) and polystyrene, or poly(butyl acrylate) or PMMA grafts were prepared by two‐step process. First, ε‐caprolactone (CL) was polymerized by ring‐opening polymerization (ROP) initiated with CDA, partly funcionalized with 2‐bromo‐isobutyryl groups (degree of functionalization was 0.5). The p(CDA‐g‐CL) copolymers were used in the second step as polyfunctional macroinitiators of ATRP of the vinyl monomer, giving densely grafted copolymers with polyester and PSt, or PBuA, or PMMA grafts. The prepared copolymers were characterized by SEC, some of them also by FTIR spectroscopy and atomic force microscopy (AFM). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 564–573, 2008     

Interaction of Fluorescein with Felodipine: A Spectrofluorometric and Thermodynamic Study

The interaction between fluorescein and felodipine (FLD) was investigated by the spectrofluorometric method. The fluorescence of FLD was quenched by fluorescein and quenching is in accordance with the Stern-Volmer relation. The binding constants of fluorescein with FLD were obtained at different temperatures. The binding constant and number of binding sites at different temperatures were calculated yielding the corresponding thermodynamic parameters ΔS, ΔH and ΔG. The distance r between the donor (FLD) and acceptor (fluorescein) molecules was obtained according to the fluorescence resonance energy transfer. The optimum conditions for the fluorometric determination of fluorescein were studied and the quenching method was successfully applied to estimate the fluorescein concentration of the pharmaceutical sample directly.     

17O NMR spectra of some butyltin(IV) acetates

The ¹⁷O NMR spectra of ¹⁷O isotope‐enriched tributyltin(IV) acetate (1) and dibutyltin(IV) diacetate (2) were recorded in various solvents over wide temperature ranges. Only a single ¹⁷O signal was observed for both oxygen atoms of the —COOSn—groups under these experimental conditions, in both non‐coordinating and coordinating solvents. The ¹⁷O NMR spectra of tert‐butyl acetate (3) were obtained for comparison. Copyright © 2002 John Wiley & Sons, Ltd.     

A sodium ion selective optode based on fluorescein octadecyl ether octadecyl ester and application in beverage and urine assay

A fast responsive sodium ion selective fluorescent optode membrane mounted on an optical fiber has been developed. The sensing membrane contained fluorescein octadecyl ether octadecyl ester (FODEE), potassium tetrakis(4-chlorophenyl) borate (KTpClPB) and a calix[4]arene tetraester in a plasticized poly(vinyl chloride) (PVC) matrix. It exhibited a reversible response to Na⁺ in 0.5 mol/l of HCl in the concentration range of 1.0×10⁻⁶ to 0.1 mol/l. The selectivity, response time, reproducibility and lifetime of the optode membrane were discussed. The practical use of this sensor was demonstrated by real sample analysis in complex sample solutions such as beverage and urine samples.     

毛细管电泳分离-激光诱导荧光检测血清中的巴氯芬

首次将新合成的柱前衍生试剂6-氧-（N-琥珀酰亚胺乙酸酯）-9-（2′-甲氧羰基）荧光素（SAM F）用于巴氯芬（B aclofen）的衍生标记,并采用毛细管电泳分离-激光诱导荧光（CE-L IF）法分离检测衍生物。研究表明,在磷酸盐缓冲溶液（pH=7.5）介质中,30℃下10m in即可完成衍生反应。反应物在pH 5.6,35mm o.lL-1的磷酸盐缓冲溶液中12m in内达到分离,检出限为6×10-10m o.lL-1。本法用于血清中巴氯芬的分析测定,回收率为95.8%—101.0%。     

Manganese(III) acetate mediated oxidation of aporphines: a convenient and useful synthesis of oxoaporphines

Manganese(III) acetate mediated oxidation of aporphines to oxoaporphines is described. The developed methodology was conveniently applied for the synthesis of naturally occurring oxoaporphine alkaloids, oxoglaucine, and atheroline, starting from commercially available boldine.     

A Unified Strategy to 6–5–6–5–6‐Membered Epipolythiodiketopiperazines: Studies towards the Total Synthesis of Scabrosin Diacetate and Haematocin

The family of epipolythiodiketopiperazine (ETP) natural products consists of over 200 members possessing a wide diversity of structures and biological activity. Recently, the subgroup of 6–5–6–5–6‐membered ETPs has gained substantial attention, which has resulted in several total syntheses. Despite all the efforts that have been invested into accessing these complex structures, no synthesis of scabrosin diacetate ( 1 a ) and its related esters has been reported. Herein, our attempts towards scabrosin diacetate ( 1 a ) and haematocin ( 3 ) starting from diketopiperazine 12 a as a late‐stage intermediate are presented. Diketopiperazine 12 a can be conveniently accessed in multigram quantities from aldehyde 18 and diketopiperazine 21 and was envisioned to serve as a general platform for the synthesis of 6–5–6–5–6‐membered ETPs.     

极谱法检测水体中的孔雀石绿

基于荧光素(SF)在pH=7.0的B-R缓冲溶液中可以产生一灵敏的还原峰,而孔雀石绿(MG)可以与荧光素络合而抑制荧光素的峰电流,建立了一种检测水体中孔雀石绿含量的极谱新方法。最佳测定体系为:1.2×10-5 mol/L的荧光素-9.0mL B-R缓冲溶液(pH=7.0)。在此体系中,于起始电位-0.40V,峰电位-0.85V,孔雀石绿含量在20~100μg/L范围内与峰电流呈线性关系,检出限为7.5μg/L。该方法用于环境水样中孔雀石绿的检测,回收率为90.5%~105.6%。     

醋酸纤维素/PET接枝共聚物的制备及性能

以低数均分子量的聚对苯二甲酸乙二醇酯(PET)、二醋酸纤维素(CDA)为原料,异孚尔酮二异氰酸酯(IPDI)为接枝剂,二月桂酸二丁基锡(DBTDL)和离子液体1-丁基-3-甲基咪唑氯盐为催化剂制备得到新型的接枝共聚物CDA-g-PET。对接枝过程进行了优化,研究了催化剂种类与接枝剂用量对接枝过程的影响,利用红外分析和广角X射线衍射分析探究了接枝机理。同时对CDA-g-PET膜进行力学性能测试,探讨了PET的加入量对CDA-g-PET膜力学性能的影响。结果表明:PET通过化学键连接接枝到CDA上,接入的PET降低了CDA的结晶性;采用DBTDL与离子液体作为联合催化剂,接枝时间由7d缩短至8h;当接枝剂IPDI的加入量,即n(IPDI)/n(PET)为1.05~1.10时CDA-g-PET无交联;随着PET含量的增加,CDA-g-PET膜与CDA膜相比拉伸强度仅降低6.55%~27.24%,断裂伸长率增加149.89%~177.81%。