Development of BINOL-Si complexes with large stokes shifts and their application as chemodosimeters for nerve agent

Three fluorescent BINOL-Si complexes (FS1, FS2 and FS3) were rationally designed and synthesized to detect diethyl chlorophosphate (DCP), a mimic of lethal nerve agents. These three fluorescent probes showed green, yellow and orange fluorescence, respectively. Moreover, the series of fluorescent probes has the characteristics of fast response time (≤ 4 s), low detection limit (0.0097 μmol/L), high sensitivity and naked eye detection. More important, a fiber optic sensor capable of detecting DCP vapor in real time was also prepared for the first time, the lowest detection limits (down to 4.4 ppb) were all lower than that of the IDLH (immediately dangerous to life or health) concentration of Sarin (7.0 ppb).     

A Double-Site Chemodosimeter for Selective Fluorescence Detection of a Nerve Agent Mimic

A novel two-site chemodosimeter (SWJT-4) based on fluorescein skeleton to detect diethyl chlorophosphate (DCP) was designed and synthesized. It is a turn-on fluorescent probe for DCP with good selectivity and obvious color change in aqueous solution. Interestingly, the two oxime groups of SWJT-4 as dual response sites initiated different reactions with DCP to form a cyano group and an isoxazole ring, respectively. The corresponding mechanism was confirmed by ¹H NMR, MS and DFT calculation. Moreover, SWJT-4 could be used as a fluorescent test paper to detect DCP vapor.     

Interrelationship between total volatile organic compounds emissions,structure and properties of natural rubber/polycaprolactone bio-blends cross-linked with peroxides

Natural rubber/polycaprolactone (NR/PCL) bio-based blends with different organic peroxides were prepared using an internal batch mixer and subsequently cross-linked at 170 °C. Two types of commonly used organic peroxides, dicumyl peroxide and di(tert-butylperoxyisopropyl)benzene peroxide, were applied as free-radical initiator. Cross-linking efficiency of NR/PCL blends were investigated using oscillating disc rheometer measurements, followed by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Total volatile organic compounds (TVOCs) emissions were determined using headspace analysis integrated with gas chromatography with flame ionization detector. Determined TVOCs emissions varying in range 21.6–52.1 μg/g and generally value of this parameter decreased with increasing content of PCL phase in studied blends or with application of more efficient di(tert-butylperoxyisopropyl)benzene peroxide as cross-linking agent. It was found that increasing of TVOCs parameter indicated deterioration of mechanical properties of NR/PCL blends, which corresponded with the changes in chemical structure and thermal properties of cross-linked NR/PCL. This confirms that evaluation of TVOCs parameter is interesting alternative for “conventional methods” to characterization of the studied bio-based blends.     

Preparation and characterization of polypropylene/waste tyre dust blends with addition of DCP and HVA-2 (PP/WTDP-HVA2)

Preparation of polypropylene (PP)/waste tyre dust (WTD) blends with addition of dicumyl peroxide (DCP) and N,N′-m-phenylenebismaleimide (HVA-2) (PP/WTD_P-HVA2) was described. The blends were characterized based on their tensile properties, swelling resistance and morphology, as well as thermal properties. The results reveal that the presence of both chemicals in PP/WTD_P-HVA2 blends brought about noticeable improvements in tensile properties, swelling resistance and interfacial adhesion. The thermal stability was also improved, indicating existence of some chemical interaction between WTD and the PP matrix in the presence of both DCP and HVA-2 during processing. The results imply that both chemicals had great influences on WTD destabilization, leading to the enlargement and intensification of the copolymer formation and, hence, improved the interfacial adhesion between WTD and the PP matrix. A competing reaction mechanism that may contribute to the property enhancement of PP/WTD_P-HVA2 blends was proposed.     

Transformation of 2,4-dichlorophenol by H2O2/UV-C, Fenton and photo-Fenton processes: Oxidation products and toxicity evolution

In the present study, H₂O₂/UV-C, Fenton and photo-Fenton treatment of 2,4-dichlorophenol was compared in terms of oxidation products and acute toxicity. The oxidation products were identified by gas chromatography-mass spectroscopy, high performance liquid chromatography and ion chromatography, whereas changes in acute toxicity were evaluated by the Vibrio fischeri luminescence inhibition assay. H₂O₂/UV-C and photo-Fenton processes ensured complete 2,4-dichlorophenolremoval, detoxification and significant mineralization. Hydroquinone and formic acid were identified as the common oxidation products of the studied advanced oxidation processes investigated. 3,5-dichloro-2-hydroxybenzaldehyde, phenol, 4-chlorophenol and 2,5-dichlorohydroquinone were identified as the additional H₂O₂/UV-C oxidation products of 2,4-dichlorophenol. Acute toxicity decreased with decreasing 2,4-dichlorophenol and increasing chloride release.     

The role of Fe(II) in the increased medicinal potency of curcumin analyzed by electrochemical methods

The formation of complexes of curcumin and Fe(II) was studied in aqueous media at pH 5.7 ± 0.1 by polarography, amperometry and spectrophotometry. The polarogram indicated formation of complexes between curcumin and Fe(II). Curcumin produces a well-defined direct current polarogram and differential pulse polarogram in 0.1 M ammonium tartrate (supporting electrolyte) at pH 5.7 ± 0.1. The stoichiometry of the Fe(II)-curcumin complex is 1 : 1. Anticancer studies on the drug and its metal complex have been performed against sarcoma cells (in-vitro), revealing the complex to be more potent in anticancer activity compared to the parent drug.     

Separation of phthalates by cyclodextrin modified micellar electrokinetic chromatography: Quantitation in perfumes

A new CE method has been developed for the simultaneous separation of a group of parent phthalates. Due to the neutral character of these compounds, the addition of several bile salts as surfactants (sodium cholate (SC), sodium deoxycholate (SDC), sodium taurodeoxycholate (STDC), sodium taurocholate (STC)) to the separation buffer was explored showing the high potential of SDC as pseudostationary phase. However, the resolution of all the phthalates was not achieved when employing only this bile salt as additive, being necessary the addition of neutral cyclodextrins (CD) and organic modifiers to the separation media. The optimized cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method consisted of the employ of a background electrolyte (BGE) containing 25 mM β-CD-100 mM SDC in a 100 mM borate buffer (pH 8.5) with a 10% (v/v) of acetonitrile, employing a voltage of 30 kV and a temperature of 25 °C. This separation medium enabled the total resolution of eight compounds and the partial resolution of two of the analytes, di-n-octyl phthalate (DNOP) and diethyl hexyl phthalate (DEHP) (Rs ~ 0.8), in only 12 min. The analytical characteristics of the developed method were studied showing their suitability for the determination of these compounds in commercial perfumes. In all the analyzed perfumes the most common phthalate was diethyl phthalate (DEP) that appeared in ten of the fifteen analyzed products. Also dimethyl phthalate (DMP), diallyl phthalate (DAP), dicyclohexyl phthalate (DCP), and di-n-pentyl phthalate (DNPP) were found in some of the analyzed samples.     

Development of BINOL-Si complexes with large stokes shifts and their application as chemodosimeters for nerve agent

Three fluorescent BINOL-Si complexes (FS1, FS2 and FS3) were rationally designed and synthesized to detect diethyl chlorophosphate (DCP), a mimic of lethal nerve agents. These three fluorescent probes showed green, yellow and orange fluorescence, respectively. Moreover, the series of fluorescent probes has the characteristics of fast response time (≤4 s), low detection limit (0.0097 μmol/L), high sensitivity and naked eye detection. More important, a fiber optic sensor capable of detecting DCP vapor in real time was also prepared for the first time, the lowest detection limits (down to 4.4 ppb) were all lower than that of the IDLH (immediately dangerous to life or health) concentration of Sarin (7.0 ppb).