• Bulletin of the Korean Chemical Society
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• v.7 no.6
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• pp.442-444
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• 1986

Starting with the readily available p-tert-butyl-calix[4]arene 2, tert-butyl groups are removed by $AlCl_3$-catalyzed de-alkylation reaction, and the calix[4]arene 3 formed is converted to the tetraacetate 4. This compound undergoes Fries rearrangement to yield p-acetylcalix[4]arene 6, which seems to be an attractive starting material for the introduction of functional groups. As a preliminary experiment p-(1-hydroxyethyl)calix[4]arene 7 is prepared by LiAlH$_4$ reduction of 6.

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.483-488
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• 1994

Tetra acyl esters of p-tert-butylcalix[4]arene and calix[4]arene, including acetyl, propionyl, butyryl and isobutyryl, are synthesized and their conformations are inferred from $^1H-NMR$ and $^{13}C-NMR$ spectra. The conformer distribution is affected by the presence of t-butyl group, whereas the acylation products of p-t-butylcalix[4]arene are the cone conformers, those of calix[4]arene are mostly partial cone and/or 1,3-alternate conformers. The conformational outcome is also affected by the method of preparation, the NaH-induced reaction is prefered to the acid-induced reaction for cone and partial cone. Interestingly, 1,2-alternate conformer was isolated in 14% yield from the butyrylation of calix[4]arene.

• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.813-816
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• 2000

The synthesis of bisphenol A-derived calixarenes has been studied by changing the protecting group of the phe-nol moiety and reaction conditions. Depending on the protecting groups,the corresponding calix[6,7,8]arenes are obtained in different rat ios. For example, whcn mono-p-tert-butyldimethylsilyl-protected bisphenol A is treated with paraformaldehyde and a catalytic amount ofaqueous KOH in refluxing p-xylene with a Dean-Stark water collector for 36 h, the corresponding calix[8]arene, calix[7]arene, and calix[6]arene are producedand separated in the ratio of about 3 : 2 : l and with overall 63% yield. The calixarenes are characterized by NMR spectroscopy and mass analysis. The X-raycrystal structure of the calix[8]arene shows a pleated loop confor-mation, stabilized by intramoIecular hydrogen bonding between the inner phenolic hydroxy groups.

• YAKHAK HOEJI
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• v.39 no.1
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• pp.61-67
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• 1995

PVC membrane electrodes based on the lipophilic neutral carrier, dibenzo-18-crown-6, cyclic oligomers of teit-butylphenol-formaidehyde condensates, calix[4]arenes as the active sensors for verapamil have been prepared and tested in a variety of plasticizers. At pH 5.0, the electrode exhibits a Nernstian response in the range of 10$^{-2}$~5$\times$10$^{-5}$ M verapamil with a slope of 49.1$\pm$0.5mV per concentration decade. The electrode constructed in this work can be used continuously for at least 1 month before any damage to the membrane occurs. And the analyses of the local anesthetic amine, which are good to select a specific compound in a mixed solution, were also accomplished by using of another neutral carrier, a DB18C6, for comparing with calix[4]arene.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1871-1873
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• 2007

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.92-96
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• 2001

The configuration of the title compound, $C_{52}H_{70}Cl_2O_6$, synthesized from a mixture of p-tert-calix[4]arene, tosylate of 2-(2-chloroethoxy)ethanol, $K_2CO_3$ and acetonitrile has a distorted cone conformation and the molecule is stabilized by two intramolecular hydrogen bonds between oxy-gen atoms of hydroxy groups and dichloride tails.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.525-528
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• 1996

Seven cali[4]arenes, having two different substituents in AAAB or AABB pattern at the upper rim of calix were synthesized by fragmentation condensation reaction of p-substituted phenol trimer (AAA) with 2,6-bishydroxymethylated 4-substituted phenol (B) or that of dimer (AA) with 2,2'-bishydroxymethylated dimer (BB). An equimolar mixture of the coupling components (trimer and monomer or dimer and dimer) was refluxed in dioxane in the presence of TiCl4to afford calix[4]arene 6 and 7 in 15-38% yield. The structure of calix[4]arenes was confirmed by elemental analysis and the 1H/13C NMR spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.177-181
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• 2004

A PVC membrane electrode for silver ion based on a new cone shaped calix[4]arene (CASCA) as membrane carrier was prepared. The electrode exhibits a Nernstian response for $Ag^+$ over a wide concentration range ($1.0{\times}10^{-1}-8.0{\times}10^{-6}$M) with a slope of 58.2 {\pm}$ 0.5 mV per decade. The limit of detection of the sensor is $5.0{\times}10^{-6}$M. The sensor has a very fast response time (~5 s) in the concentration range of ${\leq}=1.0{\times}10^{-3}$ M, and a useful working pH range of 4.0-9.5. The proposed sensor displays excellent discriminating ability toward $Ag^+$ ion with respect to common alkali, alkaline earth, transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of $Ag^+$ with EDTA and in direct determination of silver ion in wastewater of silver electroplating.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.589-594
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• 2009

We have performed DFT B3LYP/6-31G(d,p) calculations to investigate the complexation behaviors of the ethyl ester derivative of p-tert-butylcalix[6]arene (1) toward a variety of alkylammonium ions. We have studied the binding sites of these host-guest complexes focusing on the p-tert-butylcalix[6]arene pocket (endo) of 1. The smaller alkylammonium cations have the better complexation efficiency than the bulkier alkylammonium ions with the p-tert-butylcalix[6]aryl ester. The hydrogen-bonding of N-H$\ldots$O is one of the important factors for the complexation behavior of the p-tert-butylcalix[6]aryl ester, in addition to the NH-aromatic π, CH-aromatic π and electrostatic interactions, and the steric hindrance of alkylammonium cation. The hydrogen-bonded distances and angles of N-H$\ldots$O are reported for the complexes of the p-tert-butylcalix[6]aryl ester with various alkylammonium ions.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.609-616
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• 2004

Complexation of cesium ion by p-tert-butylcalix[6]arene ethyl ester was studied by NMR spectroscopy in nonpolar $CDCl_3$ and polar acetone-$d_6$ and the results were compared with each other. Analysis of temperature dependent $^1H$ spectra and titration curves reveals that both solvents result in a 1 : 1 cone-form complex with nonpolar $CDCl_3$yielding a more tightly bound one than acetone-$d_6$. Unexpectedly, at very low temperature, we have found that two phenyl ring proton peaks of equal intensity appear both in $CDCl_3$and in acetone-$d_6$ solution which gradually collapse and eventually coalesce into a single line as temperature is raised. This observation could be interpreted in terms of the chemical exchange through direct and/or indirect interconversion between two equivalent conformations possible the complex in both solvents over the temperature range observed. And broadening of $^{133}Cs$ (I = 7/2) nmr line with increasing temperature has also been observed, indicating the exchange of $^{133}Cs$ ion between the complex and the solvent. From numerical fitting of lineshape changes for one-dimensional $^1H$ and $^{133}Cs$ spectra, the exchange rate constants and other relevant parameters for this conformational interconversion and the complex-solvent exchange were deduced.