High-performance liquid chromatography-fluorometry for the determination of thiols in biological samples using N-[4-(6-dimethylamino-2-benzofuranyl) phenyl]-maleimide

The selective determination of thiols in biological samples was investigated by high-performance liquid chromatography using N-[4-(6-dimethylamino-2-benzofuranyl)phenyl] maleimide, which was found to give fluorescent products when treated with certain thiols. Six kinds of thiol (reduced glutathione, cysteine, N-acetylcysteine, cysteamine, homocysteine and coenzyme A) could be separated simultaneously within ca. 12 min and determined at final level of sensitivity. The method was successfully applied to the determination of thiols in rat tissues and plasma and in human normal serum.     

Spectrofluorimetric determination of thiols by use of N-[P-(2-benzoxazolyl)- phenyl]maleimide

The weak fluorescence of N-[P-2-benzoxazolyl)phenyl]maleimide (BOPM) can be greatly enhanced by thiol-containing compounds. A sensitive and simple spectrofluorimetric method based on the use of BOPM has been developed for the determination of thiols such as cysteine (Cys) and reduced glutathione (GSH). Calibration plots were linear in the concentration range from 0 to 1.6 × 10^–7 mol L^–1 for Cys and 0 to 1.7 × 10^–7 mol L^–1 for GSH. The detection limits (3σ) were 2.36 × 10^–10 mol L^–1 for Cys and 1.49 × 10^–10 mol L^–1 for GSH. Many other amino acids (present at 100-fold greater concentrations) did not interfere with the determination. The proposed method has been used for the determination of Cys in protein hydrolysate and cystine electrolyte or GSH in serum, with recoveries of 95.4–103.7%.     

Spectrofluorimetric determination of thiols by use of N[P-(2-benzoxazolyl)phenyl]maleimide

The weak fluorescence of N-[P-(2-benzoxazolyl)phenyl]maleimide (BOPM) can be greatly enhanced by thiol-containing compounds. A sensitive and simple spectrofluorimetric method based on the use of BOPM has been developed for the determination of thiols such as cysteine (Cys) and reduced glutathione (GSH). Calibration plots were linear in the concentration range from 0 to 1.6 x 10(-7) mol L(-1) for Cys and 0 to 1.7 x 10(-7) mol L(-1) for GSH. The detection limits (3a) were 2.36 x 10(-10) mol L(-1) for Cys and 1.49 x 10(-10) mol L(-1) for GSH. Many other amino acids (present at 100-fold greater concentrations) did not interfere with the determination. The proposed method has been used for the determination of Cys in protein hydrolysate and cystine electrolyte or GSH in serum, with recoveries of 95.4-103.7%.     

A new fluorogenic thiol-selective reagent: N-{p-[2-(6-dimethylamino)benzofuranyl]phenyl}maleimide

N-{p-[2-(6-Dimethylamino)benzofuranyl]phenyl}maleimide (DBPM), has been synthesized and found to give fluorescent products when reacted with certain thiols. The reaction is very sensitive, and concentrations as low as 10(-9)M can be detected.     

Syntheses and thermostabilities of N-[4-(N′-substituted aminocarbonyl)phenyl]maleimide polymers

Three types of novel N-[4-(N′-substituted aminocarbonyl)phenyl] maleimide (RPhMI: N-substituent (R) = phenyl, cyclohexyl, and cyclododecyl) were synthesized and homopolymerized under several conditions. In the copolymerizations of RPhMI (M₁) with styrene (ST; M₂) or methyl methacrylate (MMA; M₂), monomer reactivity ratios and Alfrey-Price Q, e values were determined. All homopolymers decomposed without softening and melting points. The initial degradation temperatures (T_d) of poly(RPhMI)s were over 320°C. The glass transition temperatures (T_g) of RPhMI copolymers were much higher than those of N-phenylmaleimide (PhMI)–ST, PhMI–MMA, N-cyclohexylmaleimide (CHMI)–ST, and CHMI–MMA copolymers. Thermal stability of the terpolymers of RPhMI with ST and acrylonitrile (AN) was higher than that of ST–AN copolymers, i.e., AS resin. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2001–2012, 1998     

N-[4-(三氟甲氧基)苯基]氨基甲酸苯酯的合成

以三氟甲氧基苯为起始原料,经硝化、加氢还原和酰化反应合成了N-[4-(三氟甲氧基)苯基]氨基甲酸苯酯,总收率84.6%,纯度98.9%,其结构经¹H NMR和MS（ESI）确证。     

Separation and determination of 4-(1,1,3,3-tetramethylbutyl)phenyl dihydrogenphosphate and di-[4-(1,1,3,3-tetramethylbutyl)phenyl] hydrogenphosphate by high-performance liquid chromatography

4-(1,1,3,3-Tetramethylbutyl)phenyl dihydrogenphosphate and di-[4-(1,1,3,3-tetramethylbutyl)phenyl] hydrogenphosphate (0.01–1 mg ml^-1) in aqueous phosphoric acid raffinates can be separated on a reversed-phase μ Bondapak C₁₈ column by gradient elution with methanol/water, and quantified at 267 nm. Raffinates are extracted with 4-methyl-2-pentanone; the two phosphates can then be determined with errors less than ±5%.     

Electrogenerated chemiluminescence of bis[4-(dimethylamino)phenyl]squaraine

For the first time, we reported the strong electrogenerated chemiluminescence of organic dye, bis[4-(dimethylamino)phenyl]squaraine (BDPSQ), a high quantum yield and light-stable species, which might find applications in ECL analysis and imaging.     

N-[4-(N''''-取代酰胺基)苯基]马来酰亚胺的合成与表征

N-取代马来酰亚胺(RMI)是一类重要的新型树脂改性单体，由于其具有刚性五元环的结构，能显著提高聚合物的玻璃化温度和热分解温度，改善材料的工艺性和力学性能。但文献对于在N-取代基团中引入杂环结构的单体合成报道很少。本文报道了由顺丁烯二酸酐、8-氨基喹啉、对甲苯胺为主要原料合成N-[4-(N’-8-喹林基)苯甲酰胺基]马来酰亚胺(QPM)和N-[4-(N’-4-甲基苯基)苯甲酰胺基]马来酰亚胺(TPM)的方法，     

Functionalized monomers based on N-(4-hydroxy phenyl)maleimide

N-(4-Hydroxy phenyl)maleimide (HPMI) is functionalized with acryloyl, methacryloyl, allyl, propargyl and cyanate groups and the structures of the materials are characterized by FTIR, ¹H NMR and ¹³C NMR. Thermal curing behaviours of the monomers and thermal stabilities of the polymers are studied using thermal analysis. Introduction of polymerizable groups shifts the curing exotherm to low temperatures, and the curing behaviour is dictated by the polymerizable substituent present in the aromatic ring. Polymer from acryloyl-functionalized monomer shows the highest thermal stability (402 °C), whereas the highest char value (49 % at 700 °C) is noted for the polymer obtained from propargyl-functionalized monomer. Polymers derived from functionalization of HPMI with acryloyl and methacryloyl showed better thermal stabilities. Thermosets formed by the thermal polymerization of HPMI functionalized with propargyl and cyanate groups showed higher char values at 700 °C in nitrogen atmosphere.     

Spectroscopic study of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)2-hydroxybenzylidene]hydroxyanilines

New homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]hydroxyanilines were synthesized. All 4-hydroxyaniline derivatives exhibited a nematic phase, while 3-hydroxyaniline and 2-hydroxyaniline derivatives exhibited only a nematic phase as the terminal alkoxy group was lengthened. Infrared spectra suggest that the 4-hydroxyaniline derivatives form intermolecular hydrogen bonding of the single bridge type, while the 3-hydroxy and 2-hydroxy derivatives form the polymer type. The Raman band at around 1360 cm^-1 exhibited large differences in intensity among these derivatives. This can be explained by the effect of intermolecular or hydrogen bonding molecular conformation.     

Spectroscopic study of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)2-hydroxybenzylidene]hydroxyanilines

New homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]hydroxyanilines were synthesized. All 4-hydroxyaniline derivatives exhibited a nematic phase, while 3-hydroxyaniline and 2-hydroxyaniline derivatives exhibited only a nematic phase as the terminal alkoxy group was lengthened. Infrared spectra suggest that the 4-hydroxyaniline derivatives form intermolecular hydrogen bonding of the single bridge type, while the 3-hydroxy and 2-hydroxy derivatives form the polymer type. The Raman band at around 1360 cm^-1 exhibited large differences in intensity among these derivatives. This can be explained by the effect of intermolecular or hydrogen bonding molecular conformation.     

New liquid crystal compounds ( )-4-[5-(2-Methylbutyl)-1,3-dioxan-2-yl]phenyl 4-alkoxybenzoate

New liquid crystal compounds, (+)-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl] phenyl 4-alkoxybenzoates (5), were synthesized. The mesomorphic behaviour of these compounds is compared with that of (+)-4-(5-alkyl-1,3-dioxan-2-yl)-phenyl 4-(2-methylbutoxy)benzoates (6). While compounds 6 exhibited a chiral smectic C phase, the corresponding compounds 5 did not. This might mean that for the appearance of a chiral smectic C phase in these types of compounds, it is necessary that the carbonyl and the chiral groups exist at nearby positions. Transition temperatures to those isotropic state for compounds 5 were lower than those for compounds 6. This result is common in both cases of (+)-4-alkoxycarbonylphenyl-4-[5-(2-methylbutyl)-1,3-dioxan-2-yl]benzoates (7), and (+)-4-(2-methylbutoxy-carbonyl)phenyl 4-(5-alkyl-1,3-dioxan-2-yl)-benzoates (8).     

Raman spectroscopy of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-aminopyridines

New homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-aminopyridines were synthesized, they exhibited a nematic phase. The temperature dependence of their Raman spectra has been observed in the spectral range 900-1800 cm^-1. Some Raman bands show a marked change in their intensity and frequency through the phase transition from crystalline solid to nematic. These bands are ascribed to the vibrational modes related to the core part of the molecule. Such behaviour can be explained by the change of molecular conformation related to the core. Some members of these series exhibited photochromism in the solid state.     

Raman spectroscopy of liquid crystalline N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-aminopyridines

New homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-aminopyridines were synthesized, they exhibited a nematic phase. The temperature dependence of their Raman spectra has been observed in the spectral range 900–1800?cm^?1. Some Raman bands show a marked change in their intensity and frequency through the phase transition from crystalline solid to nematic. These bands are ascribed to the vibrational modes related to the core part of the molecule. Such behaviour can be explained by the change of molecular conformation related to the core. Some members of these series exhibited photochromism in the solid state.     

High performance liquid chromatography post-column chemiluminescence determination of sulfonamide residues in milk at low concentration levels using bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate as chemiluminescent reagent

The determination of seven sulfonamides by means of HPLC with chemiluminescence detection is proposed for the first time. The analytes are derivatized with fluorescamine, separated and subsequently they participate in the post-column chemiluminescence (CL) peroxyoxalate system using imidazole as a catalyst. Among the different peroxyoxalates tested, bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl] oxalate provides higher sensitivities and stabilities, avoiding precipitation problems. A rigorous optimization of the significant variables by means of experimental designs has been developed in order to reconcile the chromatographic conditions with the CL reaction. The method provides detection limits in the low microgl(-1) range and has been satisfactorily applied to the analysis of spiked raw milk samples.     

Synthesis of N-[4-(2-naphthyl)]- and N-[4-(2-thienyl)methylaminobenzoyl]-dl-glutamic acids

N-[4-(2-Naphthyl)]-(IIa) and N-[4-(2-thienyl)methylaminobenzoyl]-dl-glutamic acids (IIb) have been synthesized for biological tests by the reaction of the corresponding halogen derivatives with diethyl p-aminobenzoyl-dl-glutamate (III) with subsequent hydrolysis of the esters obtained.