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All total 12 Articles be foundLead ion selective electrodes from dibenzo-18-crown-6 derivatives: An exploratory study
Jackson, Deneikah T.,Nelson, Peter N.,Booysen, Irvin N.
, (2020/11/16)
Dibenzo-18-crown-6 (DB18C6) and three of its derivatives (-COCH3, -Br, -NO2), are investigated via Density Functional Theoretical (DFT) modelling, Fourier Transform Infrared (FT-IR) and absorption spectroscopies, Differential Pulse Anodic Stripping (DPASV), Cyclic (CV) and Square Wave (SWV) voltammetries, as possible materials for preparing plasticiser free lead(II) ion selective electrodes. The spontaneous, entropy driven, interactions between lead(II) ions and DB18C6 derivatives are such that they form 1:1 complexes via coordination with the high electron density open ether cavity, except for the brominated derivative where the metal: ligand stoichiometry is 2:1 due to exo-cavity coordination via the high electron density bromine atoms. Monolayers resulting from electropolymerization of some derivatives (-H, -COCH3, -Br) and chemisorption of the -NO2 derivative, allows quantification of lead(II) ions at concentrations below 10 mg L?1 with minimal interference from other metal ions except Hg2+ and Al3+.
Crown Ether-Functionalized Polybenzoxazine for Metal Ion Adsorption
Mohamed, Mohamed Gamal,Kuo, Shiao-Wei
, p. 2420 - 2429 (2020/03/26)
In this study, we synthesized a new crown ether-functionalized benzoxazine monomer (crown-ether BZ) in high yield and purity through reduction of the Schiff base prepared from a dibenzo[18]crown-6 diamine derivative and salicylaldehyde and subsequent reaction of the resulting o-hydroxybenzylamine species with CH2O. We used differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis to examine the thermal ring opening polymerization and thermal stability of the crown-ether BZ monomer during various types of thermal treatment. DSC revealed that this crown-ether BZ monomer featured a relatively low curing temperature (210 °C; that of the typical Pa-type 3-phenyl-3,4-dihydro-2H-benzooxazine monomer: 263 °C) because the flexibility of the crown ether moiety on the main chain backbone structure catalyzed the ring opening polymerization. We also used DSC, FTIR spectroscopy, and ionic conductivity measurements to investigate the specific metal-crown ether interactions of crown-ether BZ/LiClO4 complexes. The presence of Li+ ions decreased the curing temperature significantly to 186 °C, suggesting that the metal ions functioned as an effective catalyst and promoter that accelerated the ring opening polymerization of the crown-ether BZ monomer. The ionic conductivity reached 8.3 × 10-5 S cm-1 for the crown-ether BZ/LiClO4 = 90/10 complex after thermal c? this value is higher than those of typical polymer-based systems (e.g., PEO, PCL, PMMA, and PVP) while also providing a polymer electrolyte of higher thermal stability.
Dibenzo - 18 - crown - 6 ring metal iridium complex and its application
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Paragraph 0048-0050, (2017/11/16)
The invention discloses an electrophosphorescent material containing a dibenzo-18-crown-6-based cyclometalated iridium complex, and an application thereof in a polymer electroluminescent device. According to the cyclometalated iridium complex disclosed by the invention, because dibenzo-18-crown-6 has a quite high steric hindrance, intermolecular aggregation can be effectively reduced, thus avoiding a triplet-triplet (T-T) quenching effect. Meanwhile, the dibenzo-18-crown-6 group has an electron transmission capacity to a certain extent and is capable of effectively adjusting the electron injection and transmission capacities of the iridium complex, thus greatly improving the luminescent performance of the material in the electroluminescent device. The cyclometalated iridium complex disclosed by the invention can be used as a green luminescent material and applied to an organic electroluminescent device, thus providing a new way for obtaining an efficient organic electrophosphorescent material.
Application of Bayer-Villiger reaction to the synthesis of dibenzo-18-crown-6, dibenzo-21-crown-7 and dihydroxydibenzo-18-crown-6
Utekar, Druman R.,Samant, Shriniwas D.
, p. 193 - 197 (2014/05/06)
Dibenzo-18-crown-6, dibenzo-21-crown-7 and dihydroxy dibenzo-18-crown-6 were synthesized by Bayer-Villiger oxidation strategy. Dibenzo-18-crown-6 and dibenzo-21-crown-7 could be synthesized through a three-step protocol starting from salicylaldehyde. Salicylaldehyde was reacted with bis-(2-chloroethyl)ether using K2CO3 in acetonitrile to link the two phenolic groups with the oxyethylene bridge followed by conversion of the formyl group to the hydroxy group via a Baeyer-Villiger reaction and finally linking the two phenolic group with appropriate oxyethylene bridge. The two target crown ethers were obtained in overall yield, 24% and 30%, respectively. This method has a great potential for synthesis of symmetrical as well as unsymmetrical dibenzo crowns with varying oxyethylene bridges. Baeyer-Villiger oxidation could be used to prepare dihydroxy derivative of dibenzo-18-crown-6 through acetylation of dibenzo-18-crown-6 followed by Baeyer-Villiger oxidation. The Baeyer-Villiger oxidation could be substantially accelerated using trifluoroacetic acid.
Microwave-assisted synthesis of dibenzo-crown ethers
Torrejos, Rey Eliseo C.,Nisola, Grace M.,Beltran, Arnel B.,Park, Myoung Jun,Patil, Basavaraj R.,Lee, Seong-Poong,Seo, Jeong Gil,Chung, Wook-Jin
, p. 109 - 115 (2014/03/21)
Microwave-assisted organic synthesis (MAOS) for dibenzo-substituted crown ethers is presented. Two routes were developed: (1) one-pot MAOS for symmetric dibenzo-crown ethers (DBC) and (2) a two-step MAOS via diphenol intermediates for both symmetric and asymmetric DBCs. MAOS were carried out in open or closed vessels, with or without temperature control at various microwave settings using different bases and reactants. Open vessel MAOS was limited by the volatility of reactants hence was less preferred than the closed vessel MAOS. DBC formation was highly affected by the cation size of the base, which acted as a template ion during DBCs ring closure. Closed vessel MAOS without temperature control was found most appropriate for DBC synthesis. Symmetric DBCs were conveniently obtained via one-pot MAOS whereas asymmetric DBCs were obtained from two-step MAOS via diphenol intermediates. The method was found expedient as it afforded satisfactory yields at considerably shorter reaction time than those in conventional methods.
