• Bulletin of the Korean Chemical Society
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• 제28권4호
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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.

• Mass Spectrometry Letters
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• 제7권4호
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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.

• 폴리머
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• 제37권2호
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• pp.211-217
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• 2013

Potassium tert-butoxide(t-BuOK)와 $CO_2$ 및 혹은 benzoyl chloride(BzC)를 각각 nylon 4 및 nylon 4/6 공중합체의 중합 개시제 시스템으로, 18-crown-6 ether(crown ether) 또는 tetramethyl ammonium chloride(TMAC)를 촉매로 사용하여 2-pyrrolidone(C4) 및 ${\varepsilon}$-caprolactam(C6)의 음이온 개환반응을 통하여 분자량이 매우 높은 polypyrrolidone(이하 nylon 4) 및 nylon 4 공중합체를 합성하였다. 개시제 시스템, crown ether 또는 TMAC가 중합반응에 미치는 영향을 분자량 및 수율 면에서 평가하였다. Crown ether나 TMAC를 사용하면 중합수율이 향상되었고 nylon 4의 경우 고유점도가 6.35 dL/g인 중합체를 합성할 수 있었다. 이 때 TMAC보다는 crown ether가 중합체의 분자량 상승에 더 효과적임을 확인할 수 있었다. 또한 제조된 중합체에 대해 TGA 및 DSC 열분석을 실시하였으며 분자량이 nylon 4 또는 nylon 4 공중합체의 열적 특성에 큰 영향을 미치지 않음을 확인하였다.

• 대한화학회지
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• 제40권9호
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• pp.635-639
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• 1996

실옥산 사슬에 크라운 에테르가 연결된 유연성이 큰 새로운 비스-크라운 에테르를 합성하였다. 1, 3-Bis(trimethylsiloxy)-1, 3-dimethyl-1, 3-di(4'-ethylbenz-o-18-crown-6) disiloxane(1)은 백금촉매 존재하에서 1, 3-bis(trimethylsiloxy)-1, 3-dimethyl-1, 3-disiloxane과 4'-vinylbenzo-18-crown-6의 반응에 의해 합성하였다.

• Journal of Radiation Protection and Research
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• 제21권1호
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• pp.9-16
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• 1996

환경시료 중 토양에 대한 방사성 스트론튬인 $^{89}Sr$와 $^{90}Sr$의 분석을 위해 Ca과 Sr을 분리하기 위한 방법으로 Crown ether를 이용한 추출방법을 사용하여 기존의 발연질산법과 비교하여 보았다. Crown ether를 이용한 추출방법을 기존의 발연질산법과 비교하여 보았을 때 높은 Sr 수율을 보였을 뿐만 아니라 분석에 소요되는 시간과 절차가 훨씬 빠르고 간단했다. Crown ether을 이용한 추출방법으로 원전주변 토양에 대한 방사성 스트론튬의 분석을 수행하였으며, 방사성핵종 분석에 의한 환경감시의 효율적인 수행을 위한 스트른튬 분석법을 제시하였다

• Bulletin of the Korean Chemical Society
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• 제27권10호
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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 $25{^{\circ}C}$.

• Bulletin of the Korean Chemical Society
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• 제22권11호
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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.

• Bulletin of the Korean Chemical Society
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• 제23권4호
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• pp.637-639
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• 2002

• 폴리머
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• 제30권5호
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• pp.426-431
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• 2006

Azacrown ether를 포함하는 청색발광 형광체, 9,10-bis [p-(1-aza-18-crown-6)methyl phenyl] anthracene (3)과 N,N-bis [9-(p-methylphenyl)anthracenylmethyl] -1,5-diaza-18-crown-6 (4)를 안트라센 유도체 1과 2를 mono- 및 diaza-18-crown-6와 반응시켜 합성하였다. 역시 azacrown ether를 포함하는 형광체 공중합체(5)를 1,6-diaza-18-crown-6와 1을 반응시켜 합성하였다. 제 1족, 2족 그리고 여러 가지금속 양이온을 결합시킴으로써 형광 발광세기 변화에 대한 연구를 진행하였다. 형광체는 ${\lambda}_{max}$=372nm에서 최대흡수를 그리고 ${\lambda}_{max}$=430 nm에서 최대 발광을 보여주었다. 형광체들의 최적 PH 조건을 조사하기 위해 형광 발광 세기의 pH 의존성도 측정하여 하였다.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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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.