• Title/Summary/Keyword: Crown Ether

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DFT Study of p-tert-Butylcalix[5]crown-6-ether Complexed with Alkylammonium Ions

  • Oh, Dong-Suk;Choe, Jong-In
    • Bulletin of the Korean Chemical Society
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    • v.28 no.4
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    • pp.596-600
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    • 2007
  • The structures and energies of p-tert-butylcalix[5]crown-6-ether (1) and its alkylammonium complexes have been calculated by DFT B3LYP/6-31G(d,p) method. We have studied the binding sites of these host-guest complexes focusing on the p-tert-butylcalix[5]arene pocket (endo) or the crown-6-ether moiety (exo) of 1. The smaller alkylammonium cations have the better complexation efficiency with p-tert-butylcalix[5]crown-6- ether than the bulkier alkylammonium ions. For the sec- and tert-butylammonium ions, the hydrogen-bond distances of the exo-complexes are shorter, therefore, stronger than the endo-cases. This DFT calculated result is in parallel with the trend of the experimental association constants of the branched butylammonium ions.

Collisional Activation Dissociation Mass Spectrometry Studies of Oligosaccharides Conjugated with Na+-Encapsulated Dibenzo-18-Crown-6 Ether

  • Bae, Jungeun;Song, Hwangbo;Moon, Bongjin;Oh, Han Bin
    • Mass Spectrometry Letters
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    • v.7 no.4
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    • pp.96-101
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    • 2016
  • To determine the influence of the cationization agent on the collision activated dissociation (CAD) fragmentation behavior of oligosaccharides, the CAD spectra of the singly protonated, sodiated oligosaccharides and singly sodiated and dibenzo-18-crown-6 ether conjugated oligosaccharides were carefully compared. Each of these three different species showed quite different fragmentation spectra. The comparison of singly protonated and sodiated oligosaccharide CAD spectra revealed that different cationization agents affected the cationization agent adduction sites as well as the fragmentation sites within the oligosaccharides. When the mobility of $Na^+$ was limited by the dibenzo-18-crown-6 ether encapsulation agent, the examined linear oligosaccharides showed fragmentation patterns quite different from the unmodified ones. For the dibenzo-18-crown-6 ether conjugated oligosaccharides, the charge-remote fragmentation pathways were more likely to be activated than the chargedirected pathways. This work demonstrates that dibenzo-18-crown-6 ether conjugation can potentially provide a route to selectively activate the charge-remote fragmentation pathways, albeit to a limited extent, in tandem mass spectrometry studies.

Synthesis and Characterization of Very High Molecular Weight Nylon 4 and Nylon 4/6 Copolymers (매우 높은 분자량을 갖는 Nylon 4 및 Nylon 4/6 공중합체의 합성 및 그 특성 분석)

  • Kim, Nam Cheol;Kim, Ji-Heung;Nam, Sung Woo;Jeon, Boong Soo;Yoo, Young-Tai;Kim, Young Jun
    • Polymer(Korea)
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    • v.37 no.2
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    • pp.211-217
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    • 2013
  • Potassium tert-butoxide (t-BuOK) with $CO_2$ or benzoyl chloride (BzC) as a polymerization initiator system was used with crown ether or TMAC as catalyst to synthesize very high molecular weight nylon 4 homo- and copolymers by anionic ring opening polymerization. Effect of different amounts of catalyst, crown ether and TMAC on the polymerization was studied in terms of intrinsic viscosity, yield and thermal properties. By adding crown ether or TMAC, polymers with very higher intrinsic viscosity values were obtained in a high yield. It was possible to synthesize nylon 4 homopolymer with such a high intrinsic viscosity value of 6.36 dL/g. Crown ether was found to be more efficient in terms of intrinsic viscosity and polymer yields than TMAC. Thermal analysis confirmed that molecular weight effect on the thermal properties of both nylon 4 and nylon 4 copolymer was marginal.

Synthesis of New Bis-Crown Ether (Ⅱ) : Bis-Crown Ether with Siloxane Moiety (새로운 비스-크라운 에테르의 합성(제 2보) : 실옥산 사슬에 연결된 비스-크라운 에테르)

  • Chang, Seung Hyun;Kim, Jae Yong;Chung, Kwang Bo
    • Journal of the Korean Chemical Society
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    • v.40 no.9
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    • pp.635-639
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    • 1996
  • New bis-crown ether containing siloxane chain was synthesized. 1,3-Bis(trimethylsiloxy)-1,3-dimethyl-1,3-di(4'-ethylbenzo-18-crown-6) disiloxane (1) was synthesized by reaction of 4'-vinylbenzo-18-crown-6 with 1,3-bis(trimethylsiloxy)-1,3-dimethyl-1,3-disiloxane in the presence of Pt catalyst. 4'-Vinylbenzo-18-crown-6 was prepared through five-step reaction which started from the reaction of catechol and acetic anhydride.

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Analysis of $^{89}Sr,\;^{90}Sr$ in Soil Sample Using Crown Ether/Chloroform Solvent Extraction Method (Crown Ether/Chloroform 용매추출법을 이용한 토양시료중의 $^{89}Sr,\;^{90}Sr$ 분석)

  • Hong, Kwang-Hee;Choi, Yong-Ho;Kim, Sang-Bog;Lee, Myong-Ho;Park, Hyo-Guk;Choi, Kun-Sik;Kim, Sam-Rang;Lee, Chang-Woo
    • Journal of Radiation Protection and Research
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    • v.21 no.1
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    • pp.9-16
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    • 1996
  • For the determination of radiostrontium, $^{89}Sr\;and\;^{90}Sr$ in environmental soil sample, a solvent extraction method for the separation of Ca and Sr from matrix using crown ether was investigated. In comparison with the existing fuming nitric acid method, the extraction method showed high chemical yield of strontium and provided simple and rapid analytical steps. The new analytical method applied to the determination of radiostrontium in some soil sample around a nuclear power station to show that the analytical procedure is readily applicable to the practical radioactivity monitoring.

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Synthesis of Chiral Azophenolic Pyridino-18-Crown-6 Ether and Its Enantiomeric Recognition toward Chiral Primary Amines

  • Kim, Jae-kon;Song, Su-Hee;Kim, Jae-Hong;Kim, Tae-Hyun;Kim, Ha-suck;Suh, Hong-Suk
    • Bulletin of the Korean Chemical Society
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    • v.27 no.10
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    • pp.1577-1580
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    • 2006
  • The article reports the synthesis and enantiomeric recognition of a new chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, possessing diphenyl groups as chiral barriers. The association constants for the enantiomeric recognition of chiral primary amines (7-12) using chiral azophenolic pyridino-18-crown-6 ether, (S,S)-6, were determined by UV-visible titration method in acetonitrile at $25{^{\circ}C}$.

Ab Initio Study of p-tert-Butylcalix[4]crown-6-ether Complexed with Alkyl Ammonium Cations

  • Choe, Jong In;Jang, Seok Gyu;Ham, Seong Uk;Shinkoh Nanbu;Mutsumi Aoyagi
    • Bulletin of the Korean Chemical Society
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    • v.22 no.11
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    • pp.1248-1254
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    • 2001
  • The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

Synthesis and Luminescent Characteristics of Anthracene Fluoroionophores (안트라센 형광 단위를 가지는 Fluoroionophore의 합성 및 발광특성)

  • Jeon Young-Min;Kim Jong-Gyu;Jang Ji-Geun;Chang Ho-Jung;Kim Yung-Sup;Gong Myoung-Seon
    • Polymer(Korea)
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    • v.30 no.5
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    • pp.426-431
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    • 2006
  • Novel azacrown ether containing blue -light emitting anthracene fluorophore, 9,10-bis [p-(1-aza-18-crown-6)methylphenyl] anthracene (3) and N,N-bis [9-(p-methylphenyl) anthracenyl-methyl] -1,6-diaza-18-crown-6 (4) were prepared by reacting anthracene derivatives 1 and 2 with mono- and diaza-18-crown-6, respectively Also, crown ether containing fluorophore copolymer (5) were prepared by reacting 1,6-diaza-18-crown-6 with 1. Their fluorescence emission spectral studies were investigated by binding group I, group II and various metal cations. The fluorophores showed an absorption at ${\lambda}_{max}$= 372 nm and an emission at ${\lambda}_{max}$= 430 nm. pH Dependency of fluorescence emission intensity were examined to determine the optimum pH for the fluorophores.

Development and Application of Crown Ether-based HPLC Chiral Stationary Phases

  • Hyun, Myung-Ho
    • Bulletin of the Korean Chemical Society
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    • v.26 no.8
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    • pp.1153-1163
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    • 2005
  • Crown ether-based HPLC chiral stationary phases (CSPs) have been successfully utilized in the resolution of various racemic compounds containing a primary amino group. Especially, CSPs based on chiral crown ethers incorporating chiral binaphthyl unit or tartaric acid unit and based on phenolic pseudo chiral crown ethers have shown high chiral recognition efficiency. In this account paper, a review on the development of crown etherbased HPLC CSPs, their structural characteristics and applications to the resolution of racemic compounds including chiral drugs containing a primary or secondary amino group with the variation of the type and the content of mobile phase components and with the variation of the column temperature is presented.