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A novel family of π-extended viologens has been synthesized by a concise 3-step route from simple and readily available chemicals. The π-enlargement gives the system new photophysical and electrochemical properties such as photoluminescence and changed redox potentials.
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Sulfonated phenol-formaldehyde (SPF) resin used as a cross-linker for petroleum reservoir conformance control was synthesized under alkaline conditions. The reaction process of SPF resin was evaluated by measuring the solution's viscosity with respect to phenol-formaldehyde (PF) resin. The molecular structure of SPF resin was characterized by both FTIR and HPLC-MS/MS. The influence of the formaldehyde/phenol molar ratio (F/P) and the sodium formaldehyde sulfoxylate/phenol molar ratio (S/P) on the properties of SPF were analyzed in terms of the storage time, coagulation value, molecular size, and zeta potential. The results indicate that the presence of formaldehyde sodium bisulfite could slow down condensation reaction. Phenol rings were connected by methylene bridges in the position of o-p, and sulfonated SPF resin molecules all had one sulfonate group on the oligomer structure. The storage time decreased from 87 to 6 days, and the zeta potential decreased from -3.02 to -7.70 mV with the increase in F/P (1.2-2.0). Meanwhile, the sedimentation value and the diameter increased from 3.291 × 104 to 5.045 × 104 mg/L and from 2.7 to 5.3 nm, respectively. Sulfonation could significantly increase the storage time and dispersion stability. With the increase in S/P (0.1-0.35), the storage time increased from 15 to 86 days, the sedimentation value increased from 1.927 × 104 to 5.269 × 104 mg/L, and the diameter decreased from 6.3 to 3.0 nm. This paper can present new ideas for improving the storage stability and salt tolerance of phenol-formaldehyde resin and further improving the range of its applications, which has essential reference significance.
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In this paper, ultrasound-assisted extraction (UAE) was applied to the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Rheum palmatum L. The five anthraquinones were quantified and analyzed by high performance liquid chromatography coupled with UV detection (HPLC-UV). The extraction solvent, extraction temperature and extraction time parameters, the three main factors for UAE, were optimized with response surface methodology (RSM) to obtain the highest extraction efficiency. The optimal conditions were the use of 84% methanol as solvent, an extraction time of 33 min and an extraction temperature of 67°C. Under these optimal conditions, the experimental values agreed closely with the predicted values. The analysis of variance indicated a high goodness of model fit and the success of RSM method for optimizing anthraquinones extraction in Rheum palmatum L.
Assuntos
Antraquinonas/isolamento & purificação , Emodina/análogos & derivados , Emodina/isolamento & purificação , Rheum/química , UltrassomRESUMO
A "Janus" type of hexa- cata-hexabenzocoronene with three triptyceno subunits fused symmetrically on the periphery of coronene has been synthesized using a covalent self-assembly strategy. The triptyceno subunits form a nanosized nest on one side of the aromatic plane with space-matching fullerenes such as C60 and C70 to afford shape-complementary supramolecular complexes. The formation of the complexes in solution was confirmed by 1H NMR and fluorescence titration. Four complexes with C60 or C70 were obtained and studied by single-crystal X-ray diffraction analysis. In the crystal structure, the host shows a proper tunability to adjust its conformation in accordance with the shape of the guest. The different stoichiometric ratios and various stacking patterns of the complexes suggest the diversity of this nonplanar polyaromatic host in complexation with fullerenes.